Add changelog entry

Track complement release branch when releasing
Merge branch 'master' into develop
2024-07-03 18:07:14 -06:00 · 2024-07-03 18:03:40 -06:00 · 2024-07-03 10:19:23 -06:00 · 2024-07-02 12:46:27 -05:00 · 2024-07-02 11:07:05 -05:00 · 2024-07-02 09:53:32 -06:00
54 changed files with 5671 additions and 404 deletions
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -21,6 +21,7 @@ jobs:
      trial: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.trial }}
      integration: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.integration }}
      linting: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.linting }}
+      linting_readme: ${{ !startsWith(github.ref, 'refs/pull/') || steps.filter.outputs.linting_readme }}
    steps:
    - uses: dorny/paths-filter@v3
      id: filter
@@ -72,6 +73,9 @@ jobs:
            - 'pyproject.toml'
            - 'poetry.lock'
            - '.github/workflows/tests.yml'
+          
+          linting_readme:
+            - 'README.rst'

  check-sampleconfig:
    runs-on: ubuntu-latest
@@ -269,6 +273,20 @@ jobs:

      - run: cargo fmt --check

+  # This is to detect issues with the rst file, which can otherwise cause issues
+  # when uploading packages to PyPi.
+  lint-readme:
+    runs-on: ubuntu-latest
+    needs: changes
+    if: ${{ needs.changes.outputs.linting_readme == 'true' }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.x"
+      - run: "pip install rstcheck"
+      - run: "rstcheck --report-level=WARNING README.rst"
+
  # Dummy step to gate other tests on without repeating the whole list
  linting-done:
    if: ${{ !cancelled() }} # Run this even if prior jobs were skipped
@@ -284,6 +302,7 @@ jobs:
      - lint-clippy
      - lint-clippy-nightly
      - lint-rustfmt
+      - lint-readme
    runs-on: ubuntu-latest
    steps:
      - uses: matrix-org/done-action@v2
@@ -301,6 +320,7 @@ jobs:
            lint-clippy
            lint-clippy-nightly
            lint-rustfmt
+            lint-readme


  calculate-test-jobs:
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -234,9 +234,9 @@ dependencies = [

 [[package]]
 name = "log"
-version = "0.4.21"
+version = "0.4.22"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "90ed8c1e510134f979dbc4f070f87d4313098b704861a105fe34231c70a3901c"
+checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"

 [[package]]
 name = "memchr"
@@ -505,9 +505,9 @@ dependencies = [

 [[package]]
 name = "serde_json"
-version = "1.0.117"
+version = "1.0.119"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "455182ea6142b14f93f4bc5320a2b31c1f266b66a4a5c858b013302a5d8cbfc3"
+checksum = "e8eddb61f0697cc3989c5d64b452f5488e2b8a60fd7d5076a3045076ffef8cb0"
 dependencies = [
 "itoa",
 "ryu",
--- a/changelog.d/17320.feature
+++ b/changelog.d/17320.feature
@@ -0,0 +1 @@
+Add `rooms` data to experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync` endpoint.
--- a/changelog.d/17337.feature
+++ b/changelog.d/17337.feature
@@ -0,0 +1 @@
+Add `room_types`/`not_room_types` filtering to experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync` endpoint.
--- a/changelog.d/17356.doc
+++ b/changelog.d/17356.doc
@@ -0,0 +1 @@
+Clarify `url_preview_url_blacklist` is a usability feature.
--- a/changelog.d/17362.bugfix
+++ b/changelog.d/17362.bugfix
@@ -0,0 +1 @@
+Fix rare race which causes no new to-device messages to be received from remote server.
--- a/changelog.d/17363.misc
+++ b/changelog.d/17363.misc
@@ -0,0 +1 @@
+Fix uploading packages to PyPi.
--- a/changelog.d/17365.feature
+++ b/changelog.d/17365.feature
@@ -0,0 +1 @@
+Support [MSC3916](https://github.com/matrix-org/matrix-spec-proposals/blob/rav/authentication-for-media/proposals/3916-authentication-for-media.md) by adding _matrix/client/v1/media/download endpoint.
--- a/changelog.d/17367.misc
+++ b/changelog.d/17367.misc
@@ -0,0 +1 @@
+Add CI check for the README.
--- a/changelog.d/17390.misc
+++ b/changelog.d/17390.misc
@@ -0,0 +1 @@
+Fix building debian packages on non-clean checkouts.
--- a/changelog.d/17396.misc
+++ b/changelog.d/17396.misc
@@ -0,0 +1 @@
+Pin CI to complement release branch for releases.
--- a/docker/build_debian.sh
+++ b/docker/build_debian.sh
@@ -11,6 +11,9 @@ DIST=$(cut -d ':' -f2 <<< "${distro:?}")
 cp -aT /synapse/source /synapse/build
 cd /synapse/build

+# Delete any existing `.so` files to ensure a clean build.
+rm -f /synapse/build/synapse/*.so
+
 # if this is a prerelease, set the Section accordingly.
 #
 # When the package is later added to the package repo, reprepro will use the
--- a/docker/configure_workers_and_start.py
+++ b/docker/configure_workers_and_start.py
@@ -117,7 +117,7 @@ WORKERS_CONFIG: Dict[str, Dict[str, Any]] = {
    },
    "media_repository": {
        "app": "synapse.app.generic_worker",
-        "listener_resources": ["media"],
+        "listener_resources": ["media", "client"],
        "endpoint_patterns": [
            "^/_matrix/media/",
            "^/_synapse/admin/v1/purge_media_cache$",
@@ -125,6 +125,7 @@ WORKERS_CONFIG: Dict[str, Dict[str, Any]] = {
            "^/_synapse/admin/v1/user/.*/media.*$",
            "^/_synapse/admin/v1/media/.*$",
            "^/_synapse/admin/v1/quarantine_media/.*$",
+            "^/_matrix/client/v1/media/.*$",
        ],
        # The first configured media worker will run the media background jobs
        "shared_extra_conf": {
--- a/docs/upgrade.md
+++ b/docs/upgrade.md
@@ -117,6 +117,19 @@ each upgrade are complete before moving on to the next upgrade, to avoid
 stacking them up. You can monitor the currently running background updates with
 [the Admin API](usage/administration/admin_api/background_updates.html#status).

+# Upgrading to v1.111.0
+
+## New worker endpoints for authenticated client media
+
+[Media repository workers](./workers.md#synapseappmedia_repository) handling
+Media APIs can now handle the following endpoint pattern:
+
+```
+^/_matrix/client/v1/media/.*$
+```
+
+Please update your reverse proxy configuration.
+
 # Upgrading to v1.106.0

 ## Minimum supported Rust version
--- a/docs/usage/configuration/config_documentation.md
+++ b/docs/usage/configuration/config_documentation.md
@@ -1976,9 +1976,10 @@ This will not prevent the listed domains from accessing media themselves.
 It simply prevents users on this server from downloading media originating
 from the listed servers.

-This will have no effect on media originating from the local server.
-This only affects media downloaded from other Matrix servers, to
-block domains from URL previews see [`url_preview_url_blacklist`](#url_preview_url_blacklist).
+This will have no effect on media originating from the local server. This only
+affects media downloaded from other Matrix servers, to control URL previews see
+[`url_preview_ip_range_blacklist`](#url_preview_ip_range_blacklist) or
+[`url_preview_url_blacklist`](#url_preview_url_blacklist).

 Defaults to an empty list (nothing blocked).

@@ -2130,12 +2131,14 @@ url_preview_ip_range_whitelist:
 ---
 ### `url_preview_url_blacklist`

-Optional list of URL matches that the URL preview spider is
-denied from accessing.  You should use `url_preview_ip_range_blacklist`
-in preference to this, otherwise someone could define a public DNS
-entry that points to a private IP address and circumvent the blacklist.
-This is more useful if you know there is an entire shape of URL that
-you know that will never want synapse to try to spider.
+Optional list of URL matches that the URL preview spider is denied from
+accessing.  This is a usability feature, not a security one. You should use
+`url_preview_ip_range_blacklist` in preference to this, otherwise someone could
+define a public DNS entry that points to a private IP address and circumvent
+the blacklist. Applications that perform redirects or serve different content
+when detecting that Synapse is accessing them can also bypass the blacklist.
+This is more useful if you know there is an entire shape of URL that you know
+that you do not want Synapse to preview.

 Each list entry is a dictionary of url component attributes as returned
 by urlparse.urlsplit as applied to the absolute form of the URL.  See
--- a/docs/workers.md
+++ b/docs/workers.md
@@ -739,6 +739,7 @@ An example for a federation sender instance:
 Handles the media repository. It can handle all endpoints starting with:

    /_matrix/media/
+    /_matrix/client/v1/media/

 ... and the following regular expressions matching media-specific administration APIs:

--- a/mypy.ini
+++ b/mypy.ini
@@ -96,3 +96,6 @@ ignore_missing_imports = True
 # https://github.com/twisted/treq/pull/366
 [mypy-treq.*]
 ignore_missing_imports = True
+
+[mypy-multipart.*]
+ignore_missing_imports = True
--- a/poetry.lock
+++ b/poetry.lock
@@ -1,4 +1,4 @@
-# This file is automatically @generated by Poetry 1.8.2 and should not be changed by hand.
+# This file is automatically @generated by Poetry 1.5.1 and should not be changed by hand.

 [[package]]
 name = "annotated-types"
@@ -403,43 +403,43 @@ files = [

 [[package]]
 name = "cryptography"
-version = "42.0.7"
+version = "42.0.8"
 description = "cryptography is a package which provides cryptographic recipes and primitives to Python developers."
 optional = false
 python-versions = ">=3.7"
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+    {file = "cryptography-42.0.8-cp39-abi3-win_amd64.whl", hash = "sha256:fa76fbb7596cc5839320000cdd5d0955313696d9511debab7ee7278fc8b5c84a"},
+    {file = "cryptography-42.0.8-pp310-pypy310_pp73-macosx_10_12_x86_64.whl", hash = "sha256:ba4f0a211697362e89ad822e667d8d340b4d8d55fae72cdd619389fb5912eefe"},
+    {file = "cryptography-42.0.8-pp310-pypy310_pp73-manylinux_2_28_aarch64.whl", hash = "sha256:81884c4d096c272f00aeb1f11cf62ccd39763581645b0812e99a91505fa48e0c"},
+    {file = "cryptography-42.0.8-pp310-pypy310_pp73-manylinux_2_28_x86_64.whl", hash = "sha256:c9bb2ae11bfbab395bdd072985abde58ea9860ed84e59dbc0463a5d0159f5b71"},
+    {file = "cryptography-42.0.8-pp310-pypy310_pp73-win_amd64.whl", hash = "sha256:7016f837e15b0a1c119d27ecd89b3515f01f90a8615ed5e9427e30d9cdbfed3d"},
+    {file = "cryptography-42.0.8-pp39-pypy39_pp73-macosx_10_12_x86_64.whl", hash = "sha256:5a94eccb2a81a309806027e1670a358b99b8fe8bfe9f8d329f27d72c094dde8c"},
+    {file = "cryptography-42.0.8-pp39-pypy39_pp73-manylinux_2_28_aarch64.whl", hash = "sha256:dec9b018df185f08483f294cae6ccac29e7a6e0678996587363dc352dc65c842"},
+    {file = "cryptography-42.0.8-pp39-pypy39_pp73-manylinux_2_28_x86_64.whl", hash = "sha256:343728aac38decfdeecf55ecab3264b015be68fc2816ca800db649607aeee648"},
+    {file = "cryptography-42.0.8-pp39-pypy39_pp73-win_amd64.whl", hash = "sha256:013629ae70b40af70c9a7a5db40abe5d9054e6f4380e50ce769947b73bf3caad"},
+    {file = "cryptography-42.0.8.tar.gz", hash = "sha256:8d09d05439ce7baa8e9e95b07ec5b6c886f548deb7e0f69ef25f64b3bce842f2"},
 ]

 [package.dependencies]
@@ -2039,6 +2039,20 @@ files = [
 [package.dependencies]
 six = ">=1.5"

+[[package]]
+name = "python-multipart"
+version = "0.0.9"
+description = "A streaming multipart parser for Python"
+optional = false
+python-versions = ">=3.8"
+files = [
+    {file = "python_multipart-0.0.9-py3-none-any.whl", hash = "sha256:97ca7b8ea7b05f977dc3849c3ba99d51689822fab725c3703af7c866a0c2b215"},
+    {file = "python_multipart-0.0.9.tar.gz", hash = "sha256:03f54688c663f1b7977105f021043b0793151e4cb1c1a9d4a11fc13d622c4026"},
+]
+
+[package.extras]
+dev = ["atomicwrites (==1.4.1)", "attrs (==23.2.0)", "coverage (==7.4.1)", "hatch", "invoke (==2.2.0)", "more-itertools (==10.2.0)", "pbr (==6.0.0)", "pluggy (==1.4.0)", "py (==1.11.0)", "pytest (==8.0.0)", "pytest-cov (==4.1.0)", "pytest-timeout (==2.2.0)", "pyyaml (==6.0.1)", "ruff (==0.2.1)"]
+
 [[package]]
 name = "pytz"
 version = "2022.7.1"
@@ -2906,13 +2920,13 @@ urllib3 = ">=2"

 [[package]]
 name = "types-setuptools"
-version = "69.5.0.20240423"
+version = "70.1.0.20240627"
 description = "Typing stubs for setuptools"
 optional = false
 python-versions = ">=3.8"
 files = [
-    {file = "types-setuptools-69.5.0.20240423.tar.gz", hash = "sha256:a7ba908f1746c4337d13f027fa0f4a5bcad6d1d92048219ba792b3295c58586d"},
-    {file = "types_setuptools-69.5.0.20240423-py3-none-any.whl", hash = "sha256:a4381e041510755a6c9210e26ad55b1629bc10237aeb9cb8b6bd24996b73db48"},
+    {file = "types-setuptools-70.1.0.20240627.tar.gz", hash = "sha256:385907a47b5cf302b928ce07953cd91147d5de6f3da604c31905fdf0ec309e83"},
+    {file = "types_setuptools-70.1.0.20240627-py3-none-any.whl", hash = "sha256:c7bdf05cd0a8b66868b4774c7b3c079d01ae025d8c9562bfc8bf2ff44d263c9c"},
 ]

 [[package]]
@@ -3187,4 +3201,4 @@ user-search = ["pyicu"]
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.8.0"
-content-hash = "107c8fb5c67360340854fbdba3c085fc5f9c7be24bcb592596a914eea621faea"
+content-hash = "e8d5806e10eb69bc06900fde18ea3df38f38490ab6baa73fe4a563dfb6abacba"
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -224,6 +224,8 @@ pydantic = ">=1.7.4, <3"
 # needed.
 setuptools_rust = ">=1.3"

+# This is used for parsing multipart responses
+python-multipart = ">=0.0.9"

 # Optional Dependencies
 # ---------------------
--- a/scripts-dev/release.py
+++ b/scripts-dev/release.py
@@ -71,6 +71,8 @@ def cli() -> None:

      - A checkout of the sytest repository at ../sytest

+      - A checkout of the complement repository at ../complement
+
    Then to use:

        ./scripts-dev/release.py prepare
@@ -112,10 +114,12 @@ def _prepare() -> None:
    # Make sure we're in a git repo.
    synapse_repo = get_repo_and_check_clean_checkout()
    sytest_repo = get_repo_and_check_clean_checkout("../sytest", "sytest")
+    complement_repo = get_repo_and_check_clean_checkout("../complement", "complement")

-    click.secho("Updating Synapse and Sytest git repos...")
+    click.secho("Updating Synapse, Sytest and Complement git repos...")
    synapse_repo.remote().fetch()
    sytest_repo.remote().fetch()
+    complement_repo.remote().fetch()

    # Get the current version and AST from root Synapse module.
    current_version = get_package_version()
@@ -199,16 +203,28 @@ def _prepare() -> None:
        # release type.
        if current_version.is_prerelease:
            default = release_branch_name
+            complement_default = release_branch_name
        elif release_type == "minor":
            default = "develop"
+            complement_default = "main"
        else:
            default = "master"
+            complement_default = "main"

-        branch_name = click.prompt(
+        sy_branch_name = click.prompt(
            "Which branch should the release be based on?", default=default
        )

-        for repo_name, repo in {"synapse": synapse_repo, "sytest": sytest_repo}.items():
+        complement_branch = click.prompt(
+            "Which Complement branch should the release be based on?",
+            default=complement_default,
+        )
+
+        for repo_name, (repo, branch_name) in {
+            "synapse": (synapse_repo, sy_branch_name),
+            "sytest": (sytest_repo, sy_branch_name),
+            "complement": (complement_repo, complement_branch),
+        }.items():
            base_branch = find_ref(repo, branch_name)
            if not base_branch:
                print(f"Could not find base branch {branch_name} for {repo_name}!")
@@ -230,6 +246,11 @@ def _prepare() -> None:
        # not on subsequent RCs or full releases).
        if click.confirm("Push new SyTest branch?", default=True):
            sytest_repo.git.push("-u", sytest_repo.remote().name, release_branch_name)
+        # The same special case rules apply to Complement.
+        if click.confirm("Push new Complement branch?", default=True):
+            complement_repo.git.push(
+                "-u", complement_repo.remote().name, release_branch_name
+            )

    # Switch to the release branch and ensure it's up to date.
    synapse_repo.git.checkout(release_branch_name)
@@ -630,6 +651,9 @@ def _merge_back() -> None:
    else:
        # Full release
        sytest_repo = get_repo_and_check_clean_checkout("../sytest", "sytest")
+        complement_repo = get_repo_and_check_clean_checkout(
+            "../complement", "complement"
+        )

        if click.confirm(f"Merge {branch_name} → master?", default=True):
            _merge_into(synapse_repo, branch_name, "master")
@@ -643,6 +667,9 @@ def _merge_back() -> None:
        if click.confirm("On SyTest, merge master → develop?", default=True):
            _merge_into(sytest_repo, "master", "develop")

+        if click.confirm(f"On Complement, merge {branch_name} → main?", default=True):
+            _merge_into(complement_repo, branch_name, "main")
+

@cli.command()
 def announce() -> None:
--- a/synapse/api/ratelimiting.py
+++ b/synapse/api/ratelimiting.py
@@ -130,7 +130,8 @@ class Ratelimiter:
                Overrides the value set during instantiation if set.
            burst_count: How many actions that can be performed before being limited.
                Overrides the value set during instantiation if set.
-            update: Whether to count this check as performing the action
+            update: Whether to count this check as performing the action. If the action
+                cannot be performed, the user's action count is not incremented at all.
            n_actions: The number of times the user wants to do this action. If the user
                cannot do all of the actions, the user's action count is not incremented
                at all.
--- a/synapse/events/utils.py
+++ b/synapse/events/utils.py
@@ -836,3 +836,21 @@ def maybe_upsert_event_field(
            del container[key]

    return upsert_okay
+
+
+def strip_event(event: EventBase) -> JsonDict:
+    """
+    Used for "stripped state" events which provide a simplified view of the state of a
+    room intended to help a potential joiner identify the room (relevant when the user
+    is invited or knocked).
+
+    Stripped state events can only have the `sender`, `type`, `state_key` and `content`
+    properties present.
+    """
+
+    return {
+        "type": event.type,
+        "state_key": event.state_key,
+        "content": event.content,
+        "sender": event.sender,
+    }
--- a/synapse/federation/federation_client.py
+++ b/synapse/federation/federation_client.py
@@ -1871,6 +1871,52 @@ class FederationClient(FederationBase):

        return filtered_statuses, filtered_failures

+    async def federation_download_media(
+        self,
+        destination: str,
+        media_id: str,
+        output_stream: BinaryIO,
+        max_size: int,
+        max_timeout_ms: int,
+        download_ratelimiter: Ratelimiter,
+        ip_address: str,
+    ) -> Union[
+        Tuple[int, Dict[bytes, List[bytes]], bytes],
+        Tuple[int, Dict[bytes, List[bytes]]],
+    ]:
+        try:
+            return await self.transport_layer.federation_download_media(
+                destination,
+                media_id,
+                output_stream=output_stream,
+                max_size=max_size,
+                max_timeout_ms=max_timeout_ms,
+                download_ratelimiter=download_ratelimiter,
+                ip_address=ip_address,
+            )
+        except HttpResponseException as e:
+            # If an error is received that is due to an unrecognised endpoint,
+            # fallback to the _matrix/media/v3/download endpoint. Otherwise, consider it a legitimate error
+            # and raise.
+            if not is_unknown_endpoint(e):
+                raise
+
+        logger.debug(
+            "Couldn't download media %s/%s over _matrix/federation/v1/media/download, falling back to _matrix/media/v3/download path",
+            destination,
+            media_id,
+        )
+
+        return await self.transport_layer.download_media_v3(
+            destination,
+            media_id,
+            output_stream=output_stream,
+            max_size=max_size,
+            max_timeout_ms=max_timeout_ms,
+            download_ratelimiter=download_ratelimiter,
+            ip_address=ip_address,
+        )
+
    async def download_media(
        self,
        destination: str,
--- a/synapse/federation/transport/client.py
+++ b/synapse/federation/transport/client.py
@@ -824,7 +824,6 @@ class TransportLayerClient:
        ip_address: str,
    ) -> Tuple[int, Dict[bytes, List[bytes]]]:
        path = f"/_matrix/media/r0/download/{destination}/{media_id}"
-
        return await self.client.get_file(
            destination,
            path,
@@ -852,7 +851,6 @@ class TransportLayerClient:
        ip_address: str,
    ) -> Tuple[int, Dict[bytes, List[bytes]]]:
        path = f"/_matrix/media/v3/download/{destination}/{media_id}"
-
        return await self.client.get_file(
            destination,
            path,
@@ -873,6 +871,29 @@ class TransportLayerClient:
            ip_address=ip_address,
        )

+    async def federation_download_media(
+        self,
+        destination: str,
+        media_id: str,
+        output_stream: BinaryIO,
+        max_size: int,
+        max_timeout_ms: int,
+        download_ratelimiter: Ratelimiter,
+        ip_address: str,
+    ) -> Tuple[int, Dict[bytes, List[bytes]], bytes]:
+        path = f"/_matrix/federation/v1/media/download/{media_id}"
+        return await self.client.federation_get_file(
+            destination,
+            path,
+            output_stream=output_stream,
+            max_size=max_size,
+            args={
+                "timeout_ms": str(max_timeout_ms),
+            },
+            download_ratelimiter=download_ratelimiter,
+            ip_address=ip_address,
+        )
+

 def _create_path(federation_prefix: str, path: str, *args: str) -> str:
    """
--- a/synapse/federation/transport/server/init.py
+++ b/synapse/federation/transport/server/init.py
@@ -32,8 +32,8 @@ from synapse.federation.transport.server._base import (
 from synapse.federation.transport.server.federation import (
    FEDERATION_SERVLET_CLASSES,
    FederationAccountStatusServlet,
+    FederationMediaDownloadServlet,
    FederationUnstableClientKeysClaimServlet,
-    FederationUnstableMediaDownloadServlet,
 )
 from synapse.http.server import HttpServer, JsonResource
 from synapse.http.servlet import (
@@ -316,11 +316,8 @@ def register_servlets(
            ):
                continue

-            if servletclass == FederationUnstableMediaDownloadServlet:
-                if (
-                    not hs.config.server.enable_media_repo
-                    or not hs.config.experimental.msc3916_authenticated_media_enabled
-                ):
+            if servletclass == FederationMediaDownloadServlet:
+                if not hs.config.server.enable_media_repo:
                    continue

            servletclass(
--- a/synapse/federation/transport/server/_base.py
+++ b/synapse/federation/transport/server/_base.py
@@ -362,7 +362,7 @@ class BaseFederationServlet:
                                return None
                            if (
                                func.__self__.__class__.__name__  # type: ignore
-                                == "FederationUnstableMediaDownloadServlet"
+                                == "FederationMediaDownloadServlet"
                            ):
                                response = await func(
                                    origin, content, request, *args, **kwargs
@@ -374,7 +374,7 @@ class BaseFederationServlet:
                    else:
                        if (
                            func.__self__.__class__.__name__  # type: ignore
-                            == "FederationUnstableMediaDownloadServlet"
+                            == "FederationMediaDownloadServlet"
                        ):
                            response = await func(
                                origin, content, request, *args, **kwargs
--- a/synapse/federation/transport/server/federation.py
+++ b/synapse/federation/transport/server/federation.py
@@ -790,7 +790,7 @@ class FederationAccountStatusServlet(BaseFederationServerServlet):
        return 200, {"account_statuses": statuses, "failures": failures}


-class FederationUnstableMediaDownloadServlet(BaseFederationServerServlet):
+class FederationMediaDownloadServlet(BaseFederationServerServlet):
    """
    Implementation of new federation media `/download` endpoint outlined in MSC3916. Returns
    a multipart/mixed response consisting of a JSON object and the requested media
@@ -798,7 +798,6 @@ class FederationUnstableMediaDownloadServlet(BaseFederationServerServlet):
    """

    PATH = "/media/download/(?P<media_id>[^/]*)"
-    PREFIX = FEDERATION_UNSTABLE_PREFIX + "/org.matrix.msc3916"
    RATELIMIT = True

    def __init__(
@@ -858,5 +857,5 @@ FEDERATION_SERVLET_CLASSES: Tuple[Type[BaseFederationServlet], ...] = (
    FederationV1SendKnockServlet,
    FederationMakeKnockServlet,
    FederationAccountStatusServlet,
-    FederationUnstableMediaDownloadServlet,
+    FederationMediaDownloadServlet,
 )
--- a/synapse/handlers/sliding_sync.py
+++ b/synapse/handlers/sliding_sync.py
@@ -18,22 +18,34 @@
 #
 #
 import logging
-from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
+from typing import TYPE_CHECKING, Any, Dict, List, Optional, Set, Tuple

+import attr
 from immutabledict import immutabledict

-from synapse.api.constants import AccountDataTypes, EventTypes, Membership
+from synapse.api.constants import (
+    AccountDataTypes,
+    Direction,
+    EventContentFields,
+    EventTypes,
+    Membership,
+)
 from synapse.events import EventBase
-from synapse.storage.roommember import RoomsForUser
+from synapse.events.utils import strip_event
+from synapse.handlers.relations import BundledAggregations
+from synapse.storage.databases.main.stream import CurrentStateDeltaMembership
 from synapse.types import (
+    JsonDict,
    PersistedEventPosition,
    Requester,
    RoomStreamToken,
+    StreamKeyType,
    StreamToken,
    UserID,
 )
 from synapse.types.handlers import OperationType, SlidingSyncConfig, SlidingSyncResult
 from synapse.types.state import StateFilter
+from synapse.visibility import filter_events_for_client

 if TYPE_CHECKING:
    from synapse.server import HomeServer
@@ -41,28 +53,9 @@ if TYPE_CHECKING:
 logger = logging.getLogger(__name__)


-def convert_event_to_rooms_for_user(event: EventBase) -> RoomsForUser:
-    """
-    Quick helper to convert an event to a `RoomsForUser` object.
-    """
-    # These fields should be present for all persisted events
-    assert event.internal_metadata.stream_ordering is not None
-    assert event.internal_metadata.instance_name is not None
-
-    return RoomsForUser(
-        room_id=event.room_id,
-        sender=event.sender,
-        membership=event.membership,
-        event_id=event.event_id,
-        event_pos=PersistedEventPosition(
-            event.internal_metadata.instance_name,
-            event.internal_metadata.stream_ordering,
-        ),
-        room_version_id=event.room_version.identifier,
-    )
-
-
-def filter_membership_for_sync(*, membership: str, user_id: str, sender: str) -> bool:
+def filter_membership_for_sync(
+    *, membership: str, user_id: str, sender: Optional[str]
+) -> bool:
    """
    Returns True if the membership event should be included in the sync response,
    otherwise False.
@@ -79,7 +72,54 @@ def filter_membership_for_sync(*, membership: str, user_id: str, sender: str) ->
    #
    # This logic includes kicks (leave events where the sender is not the same user) and
    # can be read as "anything that isn't a leave or a leave with a different sender".
-    return membership != Membership.LEAVE or sender != user_id
+    #
+    # When `sender=None` and `membership=Membership.LEAVE`, it means that a state reset
+    # happened that removed the user from the room, or the user was the last person
+    # locally to leave the room which caused the server to leave the room. In both
+    # cases, we can just remove the rooms since they are no longer relevant to the user.
+    # They could still be added back later if they are `newly_left`.
+    return membership != Membership.LEAVE or sender not in (user_id, None)
+
+
+# We can't freeze this class because we want to update it in place with the
+# de-duplicated data.
+@attr.s(slots=True, auto_attribs=True)
+class RoomSyncConfig:
+    """
+    Holds the config for what data we should fetch for a room in the sync response.
+
+    Attributes:
+        timeline_limit: The maximum number of events to return in the timeline.
+        required_state: The set of state events requested for the room. The
+            values are close to `StateKey` but actually use a syntax where you can
+            provide `*` wildcard and `$LAZY` for lazy room members as the `state_key` part
+            of the tuple (type, state_key).
+    """
+
+    timeline_limit: int
+    required_state: Set[Tuple[str, str]]
+
+
+@attr.s(slots=True, frozen=True, auto_attribs=True)
+class _RoomMembershipForUser:
+    """
+    Attributes:
+        event_id: The event ID of the membership event
+        event_pos: The stream position of the membership event
+        membership: The membership state of the user in the room
+        sender: The person who sent the membership event
+        newly_joined: Whether the user newly joined the room during the given token
+            range
+    """
+
+    event_id: Optional[str]
+    event_pos: PersistedEventPosition
+    membership: str
+    sender: Optional[str]
+    newly_joined: bool
+
+    def copy_and_replace(self, **kwds: Any) -> "_RoomMembershipForUser":
+        return attr.evolve(self, **kwds)


 class SlidingSyncHandler:
@@ -90,6 +130,7 @@ class SlidingSyncHandler:
        self.auth_blocking = hs.get_auth_blocking()
        self.notifier = hs.get_notifier()
        self.event_sources = hs.get_event_sources()
+        self.relations_handler = hs.get_relations_handler()
        self.rooms_to_exclude_globally = hs.config.server.rooms_to_exclude_from_sync

    async def wait_for_sync_for_user(
@@ -201,6 +242,7 @@ class SlidingSyncHandler:

        # Assemble sliding window lists
        lists: Dict[str, SlidingSyncResult.SlidingWindowList] = {}
+        relevant_room_map: Dict[str, RoomSyncConfig] = {}
        if sync_config.lists:
            # Get all of the room IDs that the user should be able to see in the sync
            # response
@@ -225,29 +267,67 @@ class SlidingSyncHandler:
                ops: List[SlidingSyncResult.SlidingWindowList.Operation] = []
                if list_config.ranges:
                    for range in list_config.ranges:
+                        sliced_room_ids = [
+                            room_id
+                            # Both sides of range are inclusive
+                            for room_id, _ in sorted_room_info[range[0] : range[1] + 1]
+                        ]
+
                        ops.append(
                            SlidingSyncResult.SlidingWindowList.Operation(
                                op=OperationType.SYNC,
                                range=range,
-                                room_ids=[
-                                    room_id
-                                    for room_id, _ in sorted_room_info[
-                                        range[0] : range[1]
-                                    ]
-                                ],
+                                room_ids=sliced_room_ids,
                            )
                        )

+                        # Take the superset of the `RoomSyncConfig` for each room
+                        for room_id in sliced_room_ids:
+                            if relevant_room_map.get(room_id) is not None:
+                                # Take the highest timeline limit
+                                if (
+                                    relevant_room_map[room_id].timeline_limit
+                                    < list_config.timeline_limit
+                                ):
+                                    relevant_room_map[room_id].timeline_limit = (
+                                        list_config.timeline_limit
+                                    )
+
+                                # Union the required state
+                                relevant_room_map[room_id].required_state.update(
+                                    list_config.required_state
+                                )
+                            else:
+                                relevant_room_map[room_id] = RoomSyncConfig(
+                                    timeline_limit=list_config.timeline_limit,
+                                    required_state=set(list_config.required_state),
+                                )
+
                lists[list_key] = SlidingSyncResult.SlidingWindowList(
                    count=len(sorted_room_info),
                    ops=ops,
                )

+        # TODO: if (sync_config.room_subscriptions):
+
+        # Fetch room data
+        rooms: Dict[str, SlidingSyncResult.RoomResult] = {}
+        for room_id, room_sync_config in relevant_room_map.items():
+            room_sync_result = await self.get_room_sync_data(
+                user=sync_config.user,
+                room_id=room_id,
+                room_sync_config=room_sync_config,
+                rooms_membership_for_user_at_to_token=sync_room_map[room_id],
+                from_token=from_token,
+                to_token=to_token,
+            )
+
+            rooms[room_id] = room_sync_result
+
        return SlidingSyncResult(
            next_pos=to_token,
            lists=lists,
-            # TODO: Gather room data for rooms in lists and `sync_config.room_subscriptions`
-            rooms={},
+            rooms=rooms,
            extensions={},
        )

@@ -256,7 +336,7 @@ class SlidingSyncHandler:
        user: UserID,
        to_token: StreamToken,
        from_token: Optional[StreamToken] = None,
-    ) -> Dict[str, RoomsForUser]:
+    ) -> Dict[str, _RoomMembershipForUser]:
        """
        Fetch room IDs that should be listed for this user in the sync response (the
        full room list that will be filtered, sorted, and sliced).
@@ -305,13 +385,17 @@ class SlidingSyncHandler:

        # Our working list of rooms that can show up in the sync response
        sync_room_id_set = {
-            room_for_user.room_id: room_for_user
-            for room_for_user in room_for_user_list
-            if filter_membership_for_sync(
+            # Note: The `room_for_user` we're assigning here will need to be fixed up
+            # (below) because they are potentially from the current snapshot time
+            # instead from the time of the `to_token`.
+            room_for_user.room_id: _RoomMembershipForUser(
+                event_id=room_for_user.event_id,
+                event_pos=room_for_user.event_pos,
                membership=room_for_user.membership,
-                user_id=user_id,
                sender=room_for_user.sender,
+                newly_joined=False,
            )
+            for room_for_user in room_for_user_list
        }

        # Get the `RoomStreamToken` that represents the spot we queried up to when we got
@@ -346,14 +430,9 @@ class SlidingSyncHandler:
        #
        # - 1a) Remove rooms that the user joined after the `to_token`
        # - 1b) Add back rooms that the user left after the `to_token`
+        # - 1c) Update room membership events to the point in time of the `to_token`
        # - 2) Add back newly_left rooms (> `from_token` and <= `to_token`)
-        #
-        # Below, we're doing two separate lookups for membership changes. We could
-        # request everything for both fixups in one range, [`from_token.room_key`,
-        # `membership_snapshot_token`), but we want to avoid raw `stream_ordering`
-        # comparison without `instance_name` (which is flawed). We could refactor
-        # `event.internal_metadata` to include `instance_name` but it might turn out a
-        # little difficult and a bigger, broader Synapse change than we want to make.
+        # - 3) Figure out which rooms are `newly_joined`

        # 1) -----------------------------------------------------

@@ -363,159 +442,198 @@ class SlidingSyncHandler:
        # If our `to_token` is already the same or ahead of the latest room membership
        # for the user, we don't need to do any "2)" fix-ups and can just straight-up
        # use the room list from the snapshot as a base (nothing has changed)
-        membership_change_events_after_to_token = []
+        current_state_delta_membership_changes_after_to_token = []
        if not membership_snapshot_token.is_before_or_eq(to_token.room_key):
-            membership_change_events_after_to_token = (
-                await self.store.get_membership_changes_for_user(
+            current_state_delta_membership_changes_after_to_token = (
+                await self.store.get_current_state_delta_membership_changes_for_user(
                    user_id,
                    from_key=to_token.room_key,
                    to_key=membership_snapshot_token,
-                    excluded_rooms=self.rooms_to_exclude_globally,
+                    excluded_room_ids=self.rooms_to_exclude_globally,
                )
            )

-        # 1) Assemble a list of the last membership events in some given ranges. Someone
-        # could have left and joined multiple times during the given range but we only
-        # care about end-result so we grab the last one.
-        last_membership_change_by_room_id_after_to_token: Dict[str, EventBase] = {}
-        # We also need the first membership event after the `to_token` so we can step
-        # backward to the previous membership that would apply to the from/to range.
-        first_membership_change_by_room_id_after_to_token: Dict[str, EventBase] = {}
-        for event in membership_change_events_after_to_token:
-            last_membership_change_by_room_id_after_to_token[event.room_id] = event
+        # 1) Assemble a list of the first membership event after the `to_token` so we can
+        # step backward to the previous membership that would apply to the from/to
+        # range.
+        first_membership_change_by_room_id_after_to_token: Dict[
+            str, CurrentStateDeltaMembership
+        ] = {}
+        for membership_change in current_state_delta_membership_changes_after_to_token:
            # Only set if we haven't already set it
            first_membership_change_by_room_id_after_to_token.setdefault(
-                event.room_id, event
+                membership_change.room_id, membership_change
            )

        # 1) Fixup
+        #
+        # Since we fetched a snapshot of the users room list at some point in time after
+        # the from/to tokens, we need to revert/rewind some membership changes to match
+        # the point in time of the `to_token`.
        for (
-            last_membership_change_after_to_token
-        ) in last_membership_change_by_room_id_after_to_token.values():
-            room_id = last_membership_change_after_to_token.room_id
+            room_id,
+            first_membership_change_after_to_token,
+        ) in first_membership_change_by_room_id_after_to_token.items():
+            # 1a) Remove rooms that the user joined after the `to_token`
+            if first_membership_change_after_to_token.prev_event_id is None:
+                sync_room_id_set.pop(room_id, None)
+            # 1b) 1c) From the first membership event after the `to_token`, step backward to the
+            # previous membership that would apply to the from/to range.
+            else:
+                # We don't expect these fields to be `None` if we have a `prev_event_id`
+                # but we're being defensive since it's possible that the prev event was
+                # culled from the database.
+                if (
+                    first_membership_change_after_to_token.prev_event_pos is not None
+                    and first_membership_change_after_to_token.prev_membership
+                    is not None
+                ):
+                    sync_room_id_set[room_id] = _RoomMembershipForUser(
+                        event_id=first_membership_change_after_to_token.prev_event_id,
+                        event_pos=first_membership_change_after_to_token.prev_event_pos,
+                        membership=first_membership_change_after_to_token.prev_membership,
+                        sender=first_membership_change_after_to_token.prev_sender,
+                        newly_joined=False,
+                    )
+                else:
+                    # If we can't find the previous membership event, we shouldn't
+                    # include the room in the sync response since we can't determine the
+                    # exact membership state and shouldn't rely on the current snapshot.
+                    sync_room_id_set.pop(room_id, None)

-            # We want to find the first membership change after the `to_token` then step
-            # backward to know the membership in the from/to range.
-            first_membership_change_after_to_token = (
-                first_membership_change_by_room_id_after_to_token.get(room_id)
-            )
-            assert first_membership_change_after_to_token is not None, (
-                "If there was a `last_membership_change_after_to_token` that we're iterating over, "
-                + "then there should be corresponding a first change. For example, even if there "
-                + "is only one event after the `to_token`, the first and last event will be same event. "
-                + "This is probably a mistake in assembling the `last_membership_change_by_room_id_after_to_token`"
-                + "/`first_membership_change_by_room_id_after_to_token` dicts above."
-            )
-            # TODO: Instead of reading from `unsigned`, refactor this to use the
-            # `current_state_delta_stream` table in the future. Probably a new
-            # `get_membership_changes_for_user()` function that uses
-            # `current_state_delta_stream` with a join to `room_memberships`. This would
-            # help in state reset scenarios since `prev_content` is looking at the
-            # current branch vs the current room state. This is all just data given to
-            # the client so no real harm to data integrity, but we'd like to be nice to
-            # the client. Since the `current_state_delta_stream` table is new, it
-            # doesn't have all events in it. Since this is Sliding Sync, if we ever need
-            # to, we can signal the client to throw all of their state away by sending
-            # "operation: RESET".
-            prev_content = first_membership_change_after_to_token.unsigned.get(
-                "prev_content", {}
-            )
-            prev_membership = prev_content.get("membership", None)
-            prev_sender = first_membership_change_after_to_token.unsigned.get(
-                "prev_sender", None
-            )
-
-            # Check if the previous membership (membership that applies to the from/to
-            # range) should be included in our `sync_room_id_set`
-            should_prev_membership_be_included = (
-                prev_membership is not None
-                and prev_sender is not None
-                and filter_membership_for_sync(
-                    membership=prev_membership,
-                    user_id=user_id,
-                    sender=prev_sender,
-                )
-            )
-
-            # Check if the last membership (membership that applies to our snapshot) was
-            # already included in our `sync_room_id_set`
-            was_last_membership_already_included = filter_membership_for_sync(
-                membership=last_membership_change_after_to_token.membership,
+        # Filter the rooms that that we have updated room membership events to the point
+        # in time of the `to_token` (from the "1)" fixups)
+        filtered_sync_room_id_set = {
+            room_id: room_membership_for_user
+            for room_id, room_membership_for_user in sync_room_id_set.items()
+            if filter_membership_for_sync(
+                membership=room_membership_for_user.membership,
                user_id=user_id,
-                sender=last_membership_change_after_to_token.sender,
+                sender=room_membership_for_user.sender,
            )
-
-            # 1a) Add back rooms that the user left after the `to_token`
-            #
-            # For example, if the last membership event after the `to_token` is a leave
-            # event, then the room was excluded from `sync_room_id_set` when we first
-            # crafted it above. We should add these rooms back as long as the user also
-            # was part of the room before the `to_token`.
-            if (
-                not was_last_membership_already_included
-                and should_prev_membership_be_included
-            ):
-                sync_room_id_set[room_id] = convert_event_to_rooms_for_user(
-                    last_membership_change_after_to_token
-                )
-            # 1b) Remove rooms that the user joined (hasn't left) after the `to_token`
-            #
-            # For example, if the last membership event after the `to_token` is a "join"
-            # event, then the room was included `sync_room_id_set` when we first crafted
-            # it above. We should remove these rooms as long as the user also wasn't
-            # part of the room before the `to_token`.
-            elif (
-                was_last_membership_already_included
-                and not should_prev_membership_be_included
-            ):
-                del sync_room_id_set[room_id]
+        }

        # 2) -----------------------------------------------------
        # We fix-up newly_left rooms after the first fixup because it may have removed
-        # some left rooms that we can figure out our newly_left in the following code
+        # some left rooms that we can figure out are newly_left in the following code

        # 2) Fetch membership changes that fall in the range from `from_token` up to `to_token`
-        membership_change_events_in_from_to_range = []
+        current_state_delta_membership_changes_in_from_to_range = []
        if from_token:
-            membership_change_events_in_from_to_range = (
-                await self.store.get_membership_changes_for_user(
+            current_state_delta_membership_changes_in_from_to_range = (
+                await self.store.get_current_state_delta_membership_changes_for_user(
                    user_id,
                    from_key=from_token.room_key,
                    to_key=to_token.room_key,
-                    excluded_rooms=self.rooms_to_exclude_globally,
+                    excluded_room_ids=self.rooms_to_exclude_globally,
                )
            )

        # 2) Assemble a list of the last membership events in some given ranges. Someone
        # could have left and joined multiple times during the given range but we only
        # care about end-result so we grab the last one.
-        last_membership_change_by_room_id_in_from_to_range: Dict[str, EventBase] = {}
-        for event in membership_change_events_in_from_to_range:
-            last_membership_change_by_room_id_in_from_to_range[event.room_id] = event
+        last_membership_change_by_room_id_in_from_to_range: Dict[
+            str, CurrentStateDeltaMembership
+        ] = {}
+        # We also want to assemble a list of the first membership events during the token
+        # range so we can step backward to the previous membership that would apply to
+        # before the token range to see if we have `newly_joined` the room.
+        first_membership_change_by_room_id_in_from_to_range: Dict[
+            str, CurrentStateDeltaMembership
+        ] = {}
+        # Keep track if the room has a non-join event in the token range so we can later
+        # tell if it was a `newly_joined` room. If the last membership event in the
+        # token range is a join and there is also some non-join in the range, we know
+        # they `newly_joined`.
+        has_non_join_event_by_room_id_in_from_to_range: Dict[str, bool] = {}
+        for (
+            membership_change
+        ) in current_state_delta_membership_changes_in_from_to_range:
+            room_id = membership_change.room_id
+
+            last_membership_change_by_room_id_in_from_to_range[room_id] = (
+                membership_change
+            )
+            # Only set if we haven't already set it
+            first_membership_change_by_room_id_in_from_to_range.setdefault(
+                room_id, membership_change
+            )
+
+            if membership_change.membership != Membership.JOIN:
+                has_non_join_event_by_room_id_in_from_to_range[room_id] = True

        # 2) Fixup
+        #
+        # 3) We also want to assemble a list of possibly newly joined rooms. Someone
+        # could have left and joined multiple times during the given range but we only
+        # care about whether they are joined at the end of the token range so we are
+        # working with the last membership even in the token range.
+        possibly_newly_joined_room_ids = set()
        for (
            last_membership_change_in_from_to_range
        ) in last_membership_change_by_room_id_in_from_to_range.values():
            room_id = last_membership_change_in_from_to_range.room_id

+            # 3)
+            if last_membership_change_in_from_to_range.membership == Membership.JOIN:
+                possibly_newly_joined_room_ids.add(room_id)
+
            # 2) Add back newly_left rooms (> `from_token` and <= `to_token`). We
            # include newly_left rooms because the last event that the user should see
            # is their own leave event
            if last_membership_change_in_from_to_range.membership == Membership.LEAVE:
-                sync_room_id_set[room_id] = convert_event_to_rooms_for_user(
-                    last_membership_change_in_from_to_range
+                filtered_sync_room_id_set[room_id] = _RoomMembershipForUser(
+                    event_id=last_membership_change_in_from_to_range.event_id,
+                    event_pos=last_membership_change_in_from_to_range.event_pos,
+                    membership=last_membership_change_in_from_to_range.membership,
+                    sender=last_membership_change_in_from_to_range.sender,
+                    newly_joined=False,
                )

-        return sync_room_id_set
+        # 3) Figure out `newly_joined`
+        for room_id in possibly_newly_joined_room_ids:
+            has_non_join_in_from_to_range = (
+                has_non_join_event_by_room_id_in_from_to_range.get(room_id, False)
+            )
+            # If the last membership event in the token range is a join and there is
+            # also some non-join in the range, we know they `newly_joined`.
+            if has_non_join_in_from_to_range:
+                # We found a `newly_joined` room (we left and joined within the token range)
+                filtered_sync_room_id_set[room_id] = filtered_sync_room_id_set[
+                    room_id
+                ].copy_and_replace(newly_joined=True)
+            else:
+                prev_event_id = first_membership_change_by_room_id_in_from_to_range[
+                    room_id
+                ].prev_event_id
+                prev_membership = first_membership_change_by_room_id_in_from_to_range[
+                    room_id
+                ].prev_membership
+
+                if prev_event_id is None:
+                    # We found a `newly_joined` room (we are joining the room for the
+                    # first time within the token range)
+                    filtered_sync_room_id_set[room_id] = filtered_sync_room_id_set[
+                        room_id
+                    ].copy_and_replace(newly_joined=True)
+                # Last resort, we need to step back to the previous membership event
+                # just before the token range to see if we're joined then or not.
+                elif prev_membership != Membership.JOIN:
+                    # We found a `newly_joined` room (we left before the token range
+                    # and joined within the token range)
+                    filtered_sync_room_id_set[room_id] = filtered_sync_room_id_set[
+                        room_id
+                    ].copy_and_replace(newly_joined=True)
+
+        return filtered_sync_room_id_set

    async def filter_rooms(
        self,
        user: UserID,
-        sync_room_map: Dict[str, RoomsForUser],
+        sync_room_map: Dict[str, _RoomMembershipForUser],
        filters: SlidingSyncConfig.SlidingSyncList.Filters,
        to_token: StreamToken,
-    ) -> Dict[str, RoomsForUser]:
+    ) -> Dict[str, _RoomMembershipForUser]:
        """
        Filter rooms based on the sync request.

@@ -583,6 +701,10 @@ class SlidingSyncHandler:
                    state_filter=StateFilter.from_types(
                        [(EventTypes.RoomEncryption, "")]
                    ),
+                    # Partially stated rooms should have all state events except for the
+                    # membership events so we don't need to wait. Plus we don't want to
+                    # block the whole sync waiting for this one room.
+                    await_full_state=False,
                )
                is_encrypted = state_at_to_token.get((EventTypes.RoomEncryption, ""))

@@ -609,11 +731,26 @@ class SlidingSyncHandler:
                ):
                    filtered_room_id_set.remove(room_id)

-        if filters.room_types:
-            raise NotImplementedError()
+        # Filter by room type (space vs room, etc). A room must match one of the types
+        # provided in the list. `None` is a valid type for rooms which do not have a
+        # room type.
+        if filters.room_types is not None or filters.not_room_types is not None:
+            # Make a copy so we don't run into an error: `Set changed size during
+            # iteration`, when we filter out and remove items
+            for room_id in list(filtered_room_id_set):
+                create_event = await self.store.get_create_event_for_room(room_id)
+                room_type = create_event.content.get(EventContentFields.ROOM_TYPE)
+                if (
+                    filters.room_types is not None
+                    and room_type not in filters.room_types
+                ):
+                    filtered_room_id_set.remove(room_id)

-        if filters.not_room_types:
-            raise NotImplementedError()
+                if (
+                    filters.not_room_types is not None
+                    and room_type in filters.not_room_types
+                ):
+                    filtered_room_id_set.remove(room_id)

        if filters.room_name_like:
            raise NotImplementedError()
@@ -629,9 +766,9 @@ class SlidingSyncHandler:

    async def sort_rooms(
        self,
-        sync_room_map: Dict[str, RoomsForUser],
+        sync_room_map: Dict[str, _RoomMembershipForUser],
        to_token: StreamToken,
-    ) -> List[Tuple[str, RoomsForUser]]:
+    ) -> List[Tuple[str, _RoomMembershipForUser]]:
        """
        Sort by `stream_ordering` of the last event that the user should see in the
        room. `stream_ordering` is unique so we get a stable sort.
@@ -678,3 +815,229 @@ class SlidingSyncHandler:
            # We want descending order
            reverse=True,
        )
+
+    async def get_room_sync_data(
+        self,
+        user: UserID,
+        room_id: str,
+        room_sync_config: RoomSyncConfig,
+        rooms_membership_for_user_at_to_token: _RoomMembershipForUser,
+        from_token: Optional[StreamToken],
+        to_token: StreamToken,
+    ) -> SlidingSyncResult.RoomResult:
+        """
+        Fetch room data for the sync response.
+
+        We fetch data according to the token range (> `from_token` and <= `to_token`).
+
+        Args:
+            user: User to fetch data for
+            room_id: The room ID to fetch data for
+            room_sync_config: Config for what data we should fetch for a room in the
+                sync response.
+            rooms_membership_for_user_at_to_token: Membership information for the user
+                in the room at the time of `to_token`.
+            from_token: The point in the stream to sync from.
+            to_token: The point in the stream to sync up to.
+        """
+
+        # Assemble the list of timeline events
+        #
+        # It would be nice to make the `rooms` response more uniform regardless of
+        # membership. Currently, we have to make all of these optional because
+        # `invite`/`knock` rooms only have `stripped_state`. See
+        # https://github.com/matrix-org/matrix-spec-proposals/pull/3575#discussion_r1653045932
+        timeline_events: Optional[List[EventBase]] = None
+        bundled_aggregations: Optional[Dict[str, BundledAggregations]] = None
+        limited: Optional[bool] = None
+        prev_batch_token: Optional[StreamToken] = None
+        num_live: Optional[int] = None
+        if (
+            room_sync_config.timeline_limit > 0
+            # No timeline for invite/knock rooms (just `stripped_state`)
+            and rooms_membership_for_user_at_to_token.membership
+            not in (Membership.INVITE, Membership.KNOCK)
+        ):
+            limited = False
+            # We want to start off using the `to_token` (vs `from_token`) because we look
+            # backwards from the `to_token` up to the `timeline_limit` and we might not
+            # reach the `from_token` before we hit the limit. We will update the room stream
+            # position once we've fetched the events to point to the earliest event fetched.
+            prev_batch_token = to_token
+
+            # We're going to paginate backwards from the `to_token`
+            from_bound = to_token.room_key
+            # People shouldn't see past their leave/ban event
+            if rooms_membership_for_user_at_to_token.membership in (
+                Membership.LEAVE,
+                Membership.BAN,
+            ):
+                from_bound = (
+                    rooms_membership_for_user_at_to_token.event_pos.to_room_stream_token()
+                )
+
+            # Determine whether we should limit the timeline to the token range.
+            #
+            # We should return historical messages (before token range) in the
+            # following cases because we want clients to be able to show a basic
+            # screen of information:
+            #  - Initial sync (because no `from_token` to limit us anyway)
+            #  - When users `newly_joined`
+            #  - TODO: For an incremental sync where we haven't sent it down this
+            #    connection before
+            to_bound = (
+                from_token.room_key
+                if from_token is not None
+                and not rooms_membership_for_user_at_to_token.newly_joined
+                else None
+            )
+
+            timeline_events, new_room_key = await self.store.paginate_room_events(
+                room_id=room_id,
+                from_key=from_bound,
+                to_key=to_bound,
+                direction=Direction.BACKWARDS,
+                # We add one so we can determine if there are enough events to saturate
+                # the limit or not (see `limited`)
+                limit=room_sync_config.timeline_limit + 1,
+                event_filter=None,
+            )
+
+            # We want to return the events in ascending order (the last event is the
+            # most recent).
+            timeline_events.reverse()
+
+            # Determine our `limited` status based on the timeline. We do this before
+            # filtering the events so we can accurately determine if there is more to
+            # paginate even if we filter out some/all events.
+            if len(timeline_events) > room_sync_config.timeline_limit:
+                limited = True
+                # Get rid of that extra "+ 1" event because we only used it to determine
+                # if we hit the limit or not
+                timeline_events = timeline_events[-room_sync_config.timeline_limit :]
+                assert timeline_events[0].internal_metadata.stream_ordering
+                new_room_key = RoomStreamToken(
+                    stream=timeline_events[0].internal_metadata.stream_ordering - 1
+                )
+
+            # Make sure we don't expose any events that the client shouldn't see
+            timeline_events = await filter_events_for_client(
+                self.storage_controllers,
+                user.to_string(),
+                timeline_events,
+                is_peeking=rooms_membership_for_user_at_to_token.membership
+                != Membership.JOIN,
+                filter_send_to_client=True,
+            )
+            # TODO: Filter out `EventTypes.CallInvite` in public rooms,
+            # see https://github.com/element-hq/synapse/issues/17359
+
+            # TODO: Handle timeline gaps (`get_timeline_gaps()`)
+
+            # Determine how many "live" events we have (events within the given token range).
+            #
+            # This is mostly useful to determine whether a given @mention event should
+            # make a noise or not. Clients cannot rely solely on the absence of
+            # `initial: true` to determine live events because if a room not in the
+            # sliding window bumps into the window because of an @mention it will have
+            # `initial: true` yet contain a single live event (with potentially other
+            # old events in the timeline)
+            num_live = 0
+            if from_token is not None:
+                for timeline_event in reversed(timeline_events):
+                    # This fields should be present for all persisted events
+                    assert timeline_event.internal_metadata.stream_ordering is not None
+                    assert timeline_event.internal_metadata.instance_name is not None
+
+                    persisted_position = PersistedEventPosition(
+                        instance_name=timeline_event.internal_metadata.instance_name,
+                        stream=timeline_event.internal_metadata.stream_ordering,
+                    )
+                    if persisted_position.persisted_after(from_token.room_key):
+                        num_live += 1
+                    else:
+                        # Since we're iterating over the timeline events in
+                        # reverse-chronological order, we can break once we hit an event
+                        # that's not live. In the future, we could potentially optimize
+                        # this more with a binary search (bisect).
+                        break
+
+            # If the timeline is `limited=True`, the client does not have all events
+            # necessary to calculate aggregations themselves.
+            if limited:
+                bundled_aggregations = (
+                    await self.relations_handler.get_bundled_aggregations(
+                        timeline_events, user.to_string()
+                    )
+                )
+
+            # Update the `prev_batch_token` to point to the position that allows us to
+            # keep paginating backwards from the oldest event we return in the timeline.
+            prev_batch_token = prev_batch_token.copy_and_replace(
+                StreamKeyType.ROOM, new_room_key
+            )
+
+        # Figure out any stripped state events for invite/knocks. This allows the
+        # potential joiner to identify the room.
+        stripped_state: List[JsonDict] = []
+        if rooms_membership_for_user_at_to_token.membership in (
+            Membership.INVITE,
+            Membership.KNOCK,
+        ):
+            # This should never happen. If someone is invited/knocked on room, then
+            # there should be an event for it.
+            assert rooms_membership_for_user_at_to_token.event_id is not None
+
+            invite_or_knock_event = await self.store.get_event(
+                rooms_membership_for_user_at_to_token.event_id
+            )
+
+            stripped_state = []
+            if invite_or_knock_event.membership == Membership.INVITE:
+                stripped_state.extend(
+                    invite_or_knock_event.unsigned.get("invite_room_state", [])
+                )
+            elif invite_or_knock_event.membership == Membership.KNOCK:
+                stripped_state.extend(
+                    invite_or_knock_event.unsigned.get("knock_room_state", [])
+                )
+
+            stripped_state.append(strip_event(invite_or_knock_event))
+
+        # TODO: Handle state resets. For example, if we see
+        # `rooms_membership_for_user_at_to_token.membership = Membership.LEAVE` but
+        # `required_state` doesn't include it, we should indicate to the client that a
+        # state reset happened. Perhaps we should indicate this by setting `initial:
+        # True` and empty `required_state`.
+
+        return SlidingSyncResult.RoomResult(
+            # TODO: Dummy value
+            name=None,
+            # TODO: Dummy value
+            avatar=None,
+            # TODO: Dummy value
+            heroes=None,
+            # TODO: Since we can't determine whether we've already sent a room down this
+            # Sliding Sync connection before (we plan to add this optimization in the
+            # future), we're always returning the requested room state instead of
+            # updates.
+            initial=True,
+            # TODO: Dummy value
+            required_state=[],
+            timeline_events=timeline_events,
+            bundled_aggregations=bundled_aggregations,
+            # TODO: Dummy value
+            is_dm=False,
+            stripped_state=stripped_state,
+            prev_batch=prev_batch_token,
+            limited=limited,
+            # TODO: Dummy values
+            joined_count=0,
+            invited_count=0,
+            # TODO: These are just dummy values. We could potentially just remove these
+            # since notifications can only really be done correctly on the client anyway
+            # (encrypted rooms).
+            notification_count=0,
+            highlight_count=0,
+            num_live=num_live,
+        )
--- a/synapse/http/client.py
+++ b/synapse/http/client.py
@@ -35,6 +35,8 @@ from typing import (
    Union,
 )

+import attr
+import multipart
 import treq
 from canonicaljson import encode_canonical_json
 from netaddr import AddrFormatError, IPAddress, IPSet
@@ -1006,6 +1008,130 @@ class _DiscardBodyWithMaxSizeProtocol(protocol.Protocol):
        self._maybe_fail()


+@attr.s(auto_attribs=True, slots=True)
+class MultipartResponse:
+    """
+    A small class to hold parsed values of a multipart response.
+    """
+
+    json: bytes = b"{}"
+    length: Optional[int] = None
+    content_type: Optional[bytes] = None
+    disposition: Optional[bytes] = None
+    url: Optional[bytes] = None
+
+
+class _MultipartParserProtocol(protocol.Protocol):
+    """
+    Protocol to read and parse a MSC3916 multipart/mixed response
+    """
+
+    transport: Optional[ITCPTransport] = None
+
+    def __init__(
+        self,
+        stream: ByteWriteable,
+        deferred: defer.Deferred,
+        boundary: str,
+        max_length: Optional[int],
+    ) -> None:
+        self.stream = stream
+        self.deferred = deferred
+        self.boundary = boundary
+        self.max_length = max_length
+        self.parser = None
+        self.multipart_response = MultipartResponse()
+        self.has_redirect = False
+        self.in_json = False
+        self.json_done = False
+        self.file_length = 0
+        self.total_length = 0
+        self.in_disposition = False
+        self.in_content_type = False
+
+    def dataReceived(self, incoming_data: bytes) -> None:
+        if self.deferred.called:
+            return
+
+        # we don't have a parser yet, instantiate it
+        if not self.parser:
+
+            def on_header_field(data: bytes, start: int, end: int) -> None:
+                if data[start:end] == b"Location":
+                    self.has_redirect = True
+                if data[start:end] == b"Content-Disposition":
+                    self.in_disposition = True
+                if data[start:end] == b"Content-Type":
+                    self.in_content_type = True
+
+            def on_header_value(data: bytes, start: int, end: int) -> None:
+                # the first header should be content-type for application/json
+                if not self.in_json and not self.json_done:
+                    assert data[start:end] == b"application/json"
+                    self.in_json = True
+                elif self.has_redirect:
+                    self.multipart_response.url = data[start:end]
+                elif self.in_content_type:
+                    self.multipart_response.content_type = data[start:end]
+                    self.in_content_type = False
+                elif self.in_disposition:
+                    self.multipart_response.disposition = data[start:end]
+                    self.in_disposition = False
+
+            def on_part_data(data: bytes, start: int, end: int) -> None:
+                # we've seen json header but haven't written the json data
+                if self.in_json and not self.json_done:
+                    self.multipart_response.json = data[start:end]
+                    self.json_done = True
+                # we have a redirect header rather than a file, and have already captured it
+                elif self.has_redirect:
+                    return
+                # otherwise we are in the file part
+                else:
+                    logger.info("Writing multipart file data to stream")
+                    try:
+                        self.stream.write(data[start:end])
+                    except Exception as e:
+                        logger.warning(
+                            f"Exception encountered writing file data to stream: {e}"
+                        )
+                        self.deferred.errback()
+                    self.file_length += end - start
+
+            callbacks = {
+                "on_header_field": on_header_field,
+                "on_header_value": on_header_value,
+                "on_part_data": on_part_data,
+            }
+            self.parser = multipart.MultipartParser(self.boundary, callbacks)
+
+        self.total_length += len(incoming_data)
+        if self.max_length is not None and self.total_length >= self.max_length:
+            self.deferred.errback(BodyExceededMaxSize())
+            # Close the connection (forcefully) since all the data will get
+            # discarded anyway.
+            assert self.transport is not None
+            self.transport.abortConnection()
+
+        try:
+            self.parser.write(incoming_data)  # type: ignore[attr-defined]
+        except Exception as e:
+            logger.warning(f"Exception writing to multipart parser: {e}")
+            self.deferred.errback()
+            return
+
+    def connectionLost(self, reason: Failure = connectionDone) -> None:
+        # If the maximum size was already exceeded, there's nothing to do.
+        if self.deferred.called:
+            return
+
+        if reason.check(ResponseDone):
+            self.multipart_response.length = self.file_length
+            self.deferred.callback(self.multipart_response)
+        else:
+            self.deferred.errback(reason)
+
+
 class _ReadBodyWithMaxSizeProtocol(protocol.Protocol):
    """A protocol which reads body to a stream, erroring if the body exceeds a maximum size."""

@@ -1091,6 +1217,32 @@ def read_body_with_max_size(
    return d


+def read_multipart_response(
+    response: IResponse, stream: ByteWriteable, boundary: str, max_length: Optional[int]
+) -> "defer.Deferred[MultipartResponse]":
+    """
+    Reads a MSC3916 multipart/mixed response and parses it, reading the file part (if it contains one) into
+    the stream passed in and returning a deferred resolving to a MultipartResponse
+
+    Args:
+        response: The HTTP response to read from.
+        stream: The file-object to write to.
+        boundary: the multipart/mixed boundary string
+        max_length: maximum allowable length of the response
+    """
+    d: defer.Deferred[MultipartResponse] = defer.Deferred()
+
+    # If the Content-Length header gives a size larger than the maximum allowed
+    # size, do not bother downloading the body.
+    if max_length is not None and response.length != UNKNOWN_LENGTH:
+        if response.length > max_length:
+            response.deliverBody(_DiscardBodyWithMaxSizeProtocol(d))
+            return d
+
+    response.deliverBody(_MultipartParserProtocol(stream, d, boundary, max_length))
+    return d
+
+
 def encode_query_args(args: Optional[QueryParams]) -> bytes:
    """
    Encodes a map of query arguments to bytes which can be appended to a URL.
--- a/synapse/http/matrixfederationclient.py
+++ b/synapse/http/matrixfederationclient.py
@@ -75,9 +75,11 @@ from synapse.http.client import (
    BlocklistingAgentWrapper,
    BodyExceededMaxSize,
    ByteWriteable,
+    SimpleHttpClient,
    _make_scheduler,
    encode_query_args,
    read_body_with_max_size,
+    read_multipart_response,
 )
 from synapse.http.connectproxyclient import BearerProxyCredentials
 from synapse.http.federation.matrix_federation_agent import MatrixFederationAgent
@@ -466,6 +468,13 @@ class MatrixFederationHttpClient:

        self._sleeper = AwakenableSleeper(self.reactor)

+        self._simple_http_client = SimpleHttpClient(
+            hs,
+            ip_blocklist=hs.config.server.federation_ip_range_blocklist,
+            ip_allowlist=hs.config.server.federation_ip_range_allowlist,
+            use_proxy=True,
+        )
+
    def wake_destination(self, destination: str) -> None:
        """Called when the remote server may have come back online."""

@@ -1553,6 +1562,189 @@ class MatrixFederationHttpClient:
        )
        return length, headers

+    async def federation_get_file(
+        self,
+        destination: str,
+        path: str,
+        output_stream: BinaryIO,
+        download_ratelimiter: Ratelimiter,
+        ip_address: str,
+        max_size: int,
+        args: Optional[QueryParams] = None,
+        retry_on_dns_fail: bool = True,
+        ignore_backoff: bool = False,
+    ) -> Tuple[int, Dict[bytes, List[bytes]], bytes]:
+        """GETs a file from a given homeserver over the federation /download endpoint
+        Args:
+            destination: The remote server to send the HTTP request to.
+            path: The HTTP path to GET.
+            output_stream: File to write the response body to.
+            download_ratelimiter: a ratelimiter to limit remote media downloads, keyed to
+                requester IP
+            ip_address: IP address of the requester
+            max_size: maximum allowable size in bytes of the file
+            args: Optional dictionary used to create the query string.
+            ignore_backoff: true to ignore the historical backoff data
+                and try the request anyway.
+
+        Returns:
+            Resolves to an (int, dict, bytes) tuple of
+            the file length, a dict of the response headers, and the file json
+
+        Raises:
+            HttpResponseException: If we get an HTTP response code >= 300
+                (except 429).
+            NotRetryingDestination: If we are not yet ready to retry this
+                server.
+            FederationDeniedError: If this destination is not on our
+                federation whitelist
+            RequestSendFailed: If there were problems connecting to the
+                remote, due to e.g. DNS failures, connection timeouts etc.
+            SynapseError: If the requested file exceeds ratelimits or the response from the
+            remote server is not a multipart response
+            AssertionError: if the resolved multipart response's length is None
+        """
+        request = MatrixFederationRequest(
+            method="GET", destination=destination, path=path, query=args
+        )
+
+        # check for a minimum balance of 1MiB in ratelimiter before initiating request
+        send_req, _ = await download_ratelimiter.can_do_action(
+            requester=None, key=ip_address, n_actions=1048576, update=False
+        )
+
+        if not send_req:
+            msg = "Requested file size exceeds ratelimits"
+            logger.warning(
+                "{%s} [%s] %s",
+                request.txn_id,
+                request.destination,
+                msg,
+            )
+            raise SynapseError(HTTPStatus.TOO_MANY_REQUESTS, msg, Codes.LIMIT_EXCEEDED)
+
+        response = await self._send_request(
+            request,
+            retry_on_dns_fail=retry_on_dns_fail,
+            ignore_backoff=ignore_backoff,
+        )
+
+        headers = dict(response.headers.getAllRawHeaders())
+
+        expected_size = response.length
+        # if we don't get an expected length then use the max length
+        if expected_size == UNKNOWN_LENGTH:
+            expected_size = max_size
+            logger.debug(
+                f"File size unknown, assuming file is max allowable size: {max_size}"
+            )
+
+        read_body, _ = await download_ratelimiter.can_do_action(
+            requester=None,
+            key=ip_address,
+            n_actions=expected_size,
+        )
+        if not read_body:
+            msg = "Requested file size exceeds ratelimits"
+            logger.warning(
+                "{%s} [%s] %s",
+                request.txn_id,
+                request.destination,
+                msg,
+            )
+            raise SynapseError(HTTPStatus.TOO_MANY_REQUESTS, msg, Codes.LIMIT_EXCEEDED)
+
+        # this should be a multipart/mixed response with the boundary string in the header
+        try:
+            raw_content_type = headers.get(b"Content-Type")
+            assert raw_content_type is not None
+            content_type = raw_content_type[0].decode("UTF-8")
+            content_type_parts = content_type.split("boundary=")
+            boundary = content_type_parts[1]
+        except Exception:
+            msg = "Remote response is malformed: expected Content-Type of multipart/mixed with a boundary present."
+            logger.warning(
+                "{%s} [%s] %s",
+                request.txn_id,
+                request.destination,
+                msg,
+            )
+            raise SynapseError(HTTPStatus.BAD_GATEWAY, msg)
+
+        try:
+            # add a byte of headroom to max size as `_MultipartParserProtocol.dataReceived` errs at >=
+            deferred = read_multipart_response(
+                response, output_stream, boundary, expected_size + 1
+            )
+            deferred.addTimeout(self.default_timeout_seconds, self.reactor)
+        except BodyExceededMaxSize:
+            msg = "Requested file is too large > %r bytes" % (expected_size,)
+            logger.warning(
+                "{%s} [%s] %s",
+                request.txn_id,
+                request.destination,
+                msg,
+            )
+            raise SynapseError(HTTPStatus.BAD_GATEWAY, msg, Codes.TOO_LARGE)
+        except defer.TimeoutError as e:
+            logger.warning(
+                "{%s} [%s] Timed out reading response - %s %s",
+                request.txn_id,
+                request.destination,
+                request.method,
+                request.uri.decode("ascii"),
+            )
+            raise RequestSendFailed(e, can_retry=True) from e
+        except ResponseFailed as e:
+            logger.warning(
+                "{%s} [%s] Failed to read response - %s %s",
+                request.txn_id,
+                request.destination,
+                request.method,
+                request.uri.decode("ascii"),
+            )
+            raise RequestSendFailed(e, can_retry=True) from e
+        except Exception as e:
+            logger.warning(
+                "{%s} [%s] Error reading response: %s",
+                request.txn_id,
+                request.destination,
+                e,
+            )
+            raise
+
+        multipart_response = await make_deferred_yieldable(deferred)
+        if not multipart_response.url:
+            assert multipart_response.length is not None
+            length = multipart_response.length
+            headers[b"Content-Type"] = [multipart_response.content_type]
+            headers[b"Content-Disposition"] = [multipart_response.disposition]
+
+        # the response contained a redirect url to download the file from
+        else:
+            str_url = multipart_response.url.decode("utf-8")
+            logger.info(
+                "{%s} [%s] File download redirected, now downloading from: %s",
+                request.txn_id,
+                request.destination,
+                str_url,
+            )
+            length, headers, _, _ = await self._simple_http_client.get_file(
+                str_url, output_stream, expected_size
+            )
+
+        logger.info(
+            "{%s} [%s] Completed: %d %s [%d bytes] %s %s",
+            request.txn_id,
+            request.destination,
+            response.code,
+            response.phrase.decode("ascii", errors="replace"),
+            length,
+            request.method,
+            request.uri.decode("ascii"),
+        )
+        return length, headers, multipart_response.json
+

 def _flatten_response_never_received(e: BaseException) -> str:
    if hasattr(e, "reasons"):
--- a/synapse/media/_base.py
+++ b/synapse/media/_base.py
@@ -221,6 +221,7 @@ def add_file_headers(
    # select private. don't bother setting Expires as all our
    # clients are smart enough to be happy with Cache-Control
    request.setHeader(b"Cache-Control", b"public,max-age=86400,s-maxage=86400")
+
    if file_size is not None:
        request.setHeader(b"Content-Length", b"%d" % (file_size,))

@@ -302,12 +303,37 @@ async def respond_with_multipart_responder(
            )
            return

+        if media_info.media_type.lower().split(";", 1)[0] in INLINE_CONTENT_TYPES:
+            disposition = "inline"
+        else:
+            disposition = "attachment"
+
+        def _quote(x: str) -> str:
+            return urllib.parse.quote(x.encode("utf-8"))
+
+        if media_info.upload_name:
+            if _can_encode_filename_as_token(media_info.upload_name):
+                disposition = "%s; filename=%s" % (
+                    disposition,
+                    media_info.upload_name,
+                )
+            else:
+                disposition = "%s; filename*=utf-8''%s" % (
+                    disposition,
+                    _quote(media_info.upload_name),
+                )
+
        from synapse.media.media_storage import MultipartFileConsumer

        # note that currently the json_object is just {}, this will change when linked media
        # is implemented
        multipart_consumer = MultipartFileConsumer(
-            clock, request, media_info.media_type, {}, media_info.media_length
+            clock,
+            request,
+            media_info.media_type,
+            {},
+            disposition,
+            media_info.media_length,
        )

        logger.debug("Responding to media request with responder %s", responder)
--- a/synapse/media/media_repository.py
+++ b/synapse/media/media_repository.py
@@ -480,6 +480,7 @@ class MediaRepository:
        name: Optional[str],
        max_timeout_ms: int,
        ip_address: str,
+        use_federation_endpoint: bool,
    ) -> None:
        """Respond to requests for remote media.

@@ -492,6 +493,8 @@ class MediaRepository:
            max_timeout_ms: the maximum number of milliseconds to wait for the
                media to be uploaded.
            ip_address: the IP address of the requester
+            use_federation_endpoint: whether to request the remote media over the new
+                federation `/download` endpoint

        Returns:
            Resolves once a response has successfully been written to request
@@ -522,6 +525,7 @@ class MediaRepository:
                max_timeout_ms,
                self.download_ratelimiter,
                ip_address,
+                use_federation_endpoint,
            )

        # We deliberately stream the file outside the lock
@@ -569,6 +573,7 @@ class MediaRepository:
                max_timeout_ms,
                self.download_ratelimiter,
                ip_address,
+                False,
            )

        # Ensure we actually use the responder so that it releases resources
@@ -585,6 +590,7 @@ class MediaRepository:
        max_timeout_ms: int,
        download_ratelimiter: Ratelimiter,
        ip_address: str,
+        use_federation_endpoint: bool,
    ) -> Tuple[Optional[Responder], RemoteMedia]:
        """Looks for media in local cache, if not there then attempt to
        download from remote server.
@@ -598,6 +604,8 @@ class MediaRepository:
            download_ratelimiter: a ratelimiter limiting remote media downloads, keyed to
                requester IP.
            ip_address: the IP address of the requester
+            use_federation_endpoint: whether to request the remote media over the new federation
+            /download endpoint

        Returns:
            A tuple of responder and the media info of the file.
@@ -629,9 +637,23 @@ class MediaRepository:
        # Failed to find the file anywhere, lets download it.

        try:
-            media_info = await self._download_remote_file(
-                server_name, media_id, max_timeout_ms, download_ratelimiter, ip_address
-            )
+            if not use_federation_endpoint:
+                media_info = await self._download_remote_file(
+                    server_name,
+                    media_id,
+                    max_timeout_ms,
+                    download_ratelimiter,
+                    ip_address,
+                )
+            else:
+                media_info = await self._federation_download_remote_file(
+                    server_name,
+                    media_id,
+                    max_timeout_ms,
+                    download_ratelimiter,
+                    ip_address,
+                )
+
        except SynapseError:
            raise
        except Exception as e:
@@ -775,6 +797,129 @@ class MediaRepository:
            quarantined_by=None,
        )

+    async def _federation_download_remote_file(
+        self,
+        server_name: str,
+        media_id: str,
+        max_timeout_ms: int,
+        download_ratelimiter: Ratelimiter,
+        ip_address: str,
+    ) -> RemoteMedia:
+        """Attempt to download the remote file from the given server name.
+        Uses the given file_id as the local id and downloads the file over the federation
+        v1 download endpoint
+
+        Args:
+            server_name: Originating server
+            media_id: The media ID of the content (as defined by the
+                remote server). This is different than the file_id, which is
+                locally generated.
+            max_timeout_ms: the maximum number of milliseconds to wait for the
+                media to be uploaded.
+            download_ratelimiter: a ratelimiter limiting remote media downloads, keyed to
+                requester IP
+            ip_address: the IP address of the requester
+
+        Returns:
+            The media info of the file.
+        """
+
+        file_id = random_string(24)
+
+        file_info = FileInfo(server_name=server_name, file_id=file_id)
+
+        async with self.media_storage.store_into_file(file_info) as (f, fname):
+            try:
+                res = await self.client.federation_download_media(
+                    server_name,
+                    media_id,
+                    output_stream=f,
+                    max_size=self.max_upload_size,
+                    max_timeout_ms=max_timeout_ms,
+                    download_ratelimiter=download_ratelimiter,
+                    ip_address=ip_address,
+                )
+                # if we had to fall back to the _matrix/media endpoint it will only return
+                # the headers and length, check the length of the tuple before unpacking
+                if len(res) == 3:
+                    length, headers, json = res
+                else:
+                    length, headers = res
+            except RequestSendFailed as e:
+                logger.warning(
+                    "Request failed fetching remote media %s/%s: %r",
+                    server_name,
+                    media_id,
+                    e,
+                )
+                raise SynapseError(502, "Failed to fetch remote media")
+
+            except HttpResponseException as e:
+                logger.warning(
+                    "HTTP error fetching remote media %s/%s: %s",
+                    server_name,
+                    media_id,
+                    e.response,
+                )
+                if e.code == twisted.web.http.NOT_FOUND:
+                    raise e.to_synapse_error()
+                raise SynapseError(502, "Failed to fetch remote media")
+
+            except SynapseError:
+                logger.warning(
+                    "Failed to fetch remote media %s/%s", server_name, media_id
+                )
+                raise
+            except NotRetryingDestination:
+                logger.warning("Not retrying destination %r", server_name)
+                raise SynapseError(502, "Failed to fetch remote media")
+            except Exception:
+                logger.exception(
+                    "Failed to fetch remote media %s/%s", server_name, media_id
+                )
+                raise SynapseError(502, "Failed to fetch remote media")
+
+            if b"Content-Type" in headers:
+                media_type = headers[b"Content-Type"][0].decode("ascii")
+            else:
+                media_type = "application/octet-stream"
+            upload_name = get_filename_from_headers(headers)
+            time_now_ms = self.clock.time_msec()
+
+            # Multiple remote media download requests can race (when using
+            # multiple media repos), so this may throw a violation constraint
+            # exception. If it does we'll delete the newly downloaded file from
+            # disk (as we're in the ctx manager).
+            #
+            # However: we've already called `finish()` so we may have also
+            # written to the storage providers. This is preferable to the
+            # alternative where we call `finish()` *after* this, where we could
+            # end up having an entry in the DB but fail to write the files to
+            # the storage providers.
+            await self.store.store_cached_remote_media(
+                origin=server_name,
+                media_id=media_id,
+                media_type=media_type,
+                time_now_ms=time_now_ms,
+                upload_name=upload_name,
+                media_length=length,
+                filesystem_id=file_id,
+            )
+
+        logger.debug("Stored remote media in file %r", fname)
+
+        return RemoteMedia(
+            media_origin=server_name,
+            media_id=media_id,
+            media_type=media_type,
+            media_length=length,
+            upload_name=upload_name,
+            created_ts=time_now_ms,
+            filesystem_id=file_id,
+            last_access_ts=time_now_ms,
+            quarantined_by=None,
+        )
+
    def _get_thumbnail_requirements(
        self, media_type: str
    ) -> Tuple[ThumbnailRequirement, ...]:
--- a/synapse/media/media_storage.py
+++ b/synapse/media/media_storage.py
@@ -401,13 +401,14 @@ class MultipartFileConsumer:
        wrapped_consumer: interfaces.IConsumer,
        file_content_type: str,
        json_object: JsonDict,
-        content_length: Optional[int] = None,
+        disposition: str,
+        content_length: Optional[int],
    ) -> None:
        self.clock = clock
        self.wrapped_consumer = wrapped_consumer
        self.json_field = json_object
        self.json_field_written = False
-        self.content_type_written = False
+        self.file_headers_written = False
        self.file_content_type = file_content_type
        self.boundary = uuid4().hex.encode("ascii")

@@ -420,6 +421,7 @@ class MultipartFileConsumer:
        self.paused = False

        self.length = content_length
+        self.disposition = disposition

    ### IConsumer APIs ###

@@ -488,11 +490,13 @@ class MultipartFileConsumer:
            self.json_field_written = True

        # if we haven't written the content type yet, do so
-        if not self.content_type_written:
+        if not self.file_headers_written:
            type = self.file_content_type.encode("utf-8")
            content_type = Header(b"Content-Type", type)
-            self.wrapped_consumer.write(bytes(content_type) + CRLF + CRLF)
-            self.content_type_written = True
+            self.wrapped_consumer.write(bytes(content_type) + CRLF)
+            disp_header = Header(b"Content-Disposition", self.disposition)
+            self.wrapped_consumer.write(bytes(disp_header) + CRLF + CRLF)
+            self.file_headers_written = True

        self.wrapped_consumer.write(data)

@@ -506,7 +510,6 @@ class MultipartFileConsumer:
        producing data for good.
        """
        assert self.producer is not None
-
        self.paused = True
        self.producer.stopProducing()

@@ -518,7 +521,6 @@ class MultipartFileConsumer:
        the time being, and to stop until C{resumeProducing()} is called.
        """
        assert self.producer is not None
-
        self.paused = True

        if self.streaming:
@@ -549,7 +551,7 @@ class MultipartFileConsumer:
        """
        if not self.length:
            return None
-        # calculate length of json field and content-type header
+        # calculate length of json field and content-type, disposition headers
        json_field = json.dumps(self.json_field)
        json_bytes = json_field.encode("utf-8")
        json_length = len(json_bytes)
@@ -558,9 +560,13 @@ class MultipartFileConsumer:
        content_type = Header(b"Content-Type", type)
        type_length = len(bytes(content_type))

-        # 154 is the length of the elements that aren't variable, ie
+        disp = self.disposition.encode("utf-8")
+        disp_header = Header(b"Content-Disposition", disp)
+        disp_length = len(bytes(disp_header))
+
+        # 156 is the length of the elements that aren't variable, ie
        # CRLFs and boundary strings, etc
-        self.length += json_length + type_length + 154
+        self.length += json_length + type_length + disp_length + 156

        return self.length

@@ -569,7 +575,6 @@ class MultipartFileConsumer:
    async def _resumeProducingRepeatedly(self) -> None:
        assert self.producer is not None
        assert not self.streaming
-
        producer = cast("interfaces.IPullProducer", self.producer)

        self.paused = False
--- a/synapse/rest/init.py
+++ b/synapse/rest/init.py
@@ -145,6 +145,10 @@ class ClientRestResource(JsonResource):
        password_policy.register_servlets(hs, client_resource)
        knock.register_servlets(hs, client_resource)
        appservice_ping.register_servlets(hs, client_resource)
+        if hs.config.server.enable_media_repo:
+            from synapse.rest.client import media
+
+            media.register_servlets(hs, client_resource)

        # moving to /_synapse/admin
        if is_main_process:
--- a/synapse/rest/client/media.py
+++ b/synapse/rest/client/media.py
@@ -22,6 +22,7 @@

 import logging
 import re
+from typing import Optional

 from synapse.http.server import (
    HttpServer,
@@ -194,14 +195,76 @@ class UnstableThumbnailResource(RestServlet):
            self.media_repo.mark_recently_accessed(server_name, media_id)


+class DownloadResource(RestServlet):
+    PATTERNS = [
+        re.compile(
+            "/_matrix/client/v1/media/download/(?P<server_name>[^/]*)/(?P<media_id>[^/]*)(/(?P<file_name>[^/]*))?$"
+        )
+    ]
+
+    def __init__(self, hs: "HomeServer", media_repo: "MediaRepository"):
+        super().__init__()
+        self.media_repo = media_repo
+        self._is_mine_server_name = hs.is_mine_server_name
+        self.auth = hs.get_auth()
+
+    async def on_GET(
+        self,
+        request: SynapseRequest,
+        server_name: str,
+        media_id: str,
+        file_name: Optional[str] = None,
+    ) -> None:
+        # Validate the server name, raising if invalid
+        parse_and_validate_server_name(server_name)
+
+        await self.auth.get_user_by_req(request)
+
+        set_cors_headers(request)
+        set_corp_headers(request)
+        request.setHeader(
+            b"Content-Security-Policy",
+            b"sandbox;"
+            b" default-src 'none';"
+            b" script-src 'none';"
+            b" plugin-types application/pdf;"
+            b" style-src 'unsafe-inline';"
+            b" media-src 'self';"
+            b" object-src 'self';",
+        )
+        # Limited non-standard form of CSP for IE11
+        request.setHeader(b"X-Content-Security-Policy", b"sandbox;")
+        request.setHeader(b"Referrer-Policy", b"no-referrer")
+        max_timeout_ms = parse_integer(
+            request, "timeout_ms", default=DEFAULT_MAX_TIMEOUT_MS
+        )
+        max_timeout_ms = min(max_timeout_ms, MAXIMUM_ALLOWED_MAX_TIMEOUT_MS)
+
+        if self._is_mine_server_name(server_name):
+            await self.media_repo.get_local_media(
+                request, media_id, file_name, max_timeout_ms
+            )
+        else:
+            ip_address = request.getClientAddress().host
+            await self.media_repo.get_remote_media(
+                request,
+                server_name,
+                media_id,
+                file_name,
+                max_timeout_ms,
+                ip_address,
+                True,
+            )
+
+
 def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
-    if hs.config.experimental.msc3916_authenticated_media_enabled:
-        media_repo = hs.get_media_repository()
-        if hs.config.media.url_preview_enabled:
-            UnstablePreviewURLServlet(
-                hs, media_repo, media_repo.media_storage
-            ).register(http_server)
-        UnstableMediaConfigResource(hs).register(http_server)
-        UnstableThumbnailResource(hs, media_repo, media_repo.media_storage).register(
+    media_repo = hs.get_media_repository()
+    if hs.config.media.url_preview_enabled:
+        UnstablePreviewURLServlet(hs, media_repo, media_repo.media_storage).register(
            http_server
        )
+    UnstableMediaConfigResource(hs).register(http_server)
+    UnstableThumbnailResource(hs, media_repo, media_repo.media_storage).register(
+        http_server
+    )
+    DownloadResource(hs, media_repo).register(http_server)
--- a/synapse/rest/client/sync.py
+++ b/synapse/rest/client/sync.py
@@ -761,7 +761,6 @@ class SlidingSyncRestServlet(RestServlet):
            "lists": {
                "foo-list": {
                    "ranges": [ [0, 99] ],
-                    "sort": [ "by_notification_level", "by_recency", "by_name" ],
                    "required_state": [
                        ["m.room.join_rules", ""],
                        ["m.room.history_visibility", ""],
@@ -771,7 +770,6 @@ class SlidingSyncRestServlet(RestServlet):
                    "filters": {
                        "is_dm": true
                    },
-                    "bump_event_types": [ "m.room.message", "m.room.encrypted" ],
                }
            },
            // Room Subscriptions API
@@ -779,10 +777,6 @@ class SlidingSyncRestServlet(RestServlet):
                "!sub1:bar": {
                    "required_state": [ ["*","*"] ],
                    "timeline_limit": 10,
-                    "include_old_rooms": {
-                        "timeline_limit": 1,
-                        "required_state": [ ["m.room.tombstone", ""], ["m.room.create", ""] ],
-                    }
                }
            },
            // Extensions API
@@ -791,7 +785,7 @@ class SlidingSyncRestServlet(RestServlet):

    Response JSON::
        {
-            "next_pos": "s58_224_0_13_10_1_1_16_0_1",
+            "pos": "s58_224_0_13_10_1_1_16_0_1",
            "lists": {
                "foo-list": {
                    "count": 1337,
@@ -830,7 +824,8 @@ class SlidingSyncRestServlet(RestServlet):
                    "joined_count": 41,
                    "invited_count": 1,
                    "notification_count": 1,
-                    "highlight_count": 0
+                    "highlight_count": 0,
+                    "num_live": 2"
                },
                // rooms from list
                "!foo:bar": {
@@ -855,7 +850,8 @@ class SlidingSyncRestServlet(RestServlet):
                    "joined_count": 4,
                    "invited_count": 0,
                    "notification_count": 54,
-                    "highlight_count": 3
+                    "highlight_count": 3,
+                    "num_live": 1,
                },
                 // ... 99 more items
            },
@@ -871,10 +867,11 @@ class SlidingSyncRestServlet(RestServlet):
        super().__init__()
        self.auth = hs.get_auth()
        self.store = hs.get_datastores().main
+        self.clock = hs.get_clock()
        self.filtering = hs.get_filtering()
        self.sliding_sync_handler = hs.get_sliding_sync_handler()
+        self.event_serializer = hs.get_event_client_serializer()

-    # TODO: Update this to `on_GET` once we figure out how we want to handle params
    async def on_POST(self, request: SynapseRequest) -> Tuple[int, JsonDict]:
        requester = await self.auth.get_user_by_req(request, allow_guest=True)
        user = requester.user
@@ -920,22 +917,25 @@ class SlidingSyncRestServlet(RestServlet):
            logger.info("Client has disconnected; not serializing response.")
            return 200, {}

-        response_content = await self.encode_response(sliding_sync_results)
+        response_content = await self.encode_response(requester, sliding_sync_results)

        return 200, response_content

    # TODO: Is there a better way to encode things?
    async def encode_response(
        self,
+        requester: Requester,
        sliding_sync_result: SlidingSyncResult,
    ) -> JsonDict:
        response: JsonDict = defaultdict(dict)

-        response["next_pos"] = await sliding_sync_result.next_pos.to_string(self.store)
+        response["pos"] = await sliding_sync_result.next_pos.to_string(self.store)
        serialized_lists = self.encode_lists(sliding_sync_result.lists)
        if serialized_lists:
            response["lists"] = serialized_lists
-        response["rooms"] = {}  # TODO: sliding_sync_result.rooms
+        response["rooms"] = await self.encode_rooms(
+            requester, sliding_sync_result.rooms
+        )
        response["extensions"] = {}  # TODO: sliding_sync_result.extensions

        return response
@@ -961,6 +961,92 @@ class SlidingSyncRestServlet(RestServlet):

        return serialized_lists

+    async def encode_rooms(
+        self,
+        requester: Requester,
+        rooms: Dict[str, SlidingSyncResult.RoomResult],
+    ) -> JsonDict:
+        time_now = self.clock.time_msec()
+
+        serialize_options = SerializeEventConfig(
+            event_format=format_event_for_client_v2_without_room_id,
+            requester=requester,
+        )
+
+        serialized_rooms: Dict[str, JsonDict] = {}
+        for room_id, room_result in rooms.items():
+            serialized_rooms[room_id] = {
+                "joined_count": room_result.joined_count,
+                "invited_count": room_result.invited_count,
+                "notification_count": room_result.notification_count,
+                "highlight_count": room_result.highlight_count,
+            }
+
+            if room_result.name:
+                serialized_rooms[room_id]["name"] = room_result.name
+
+            if room_result.avatar:
+                serialized_rooms[room_id]["avatar"] = room_result.avatar
+
+            if room_result.heroes:
+                serialized_rooms[room_id]["heroes"] = room_result.heroes
+
+            # We should only include the `initial` key if it's `True` to save bandwidth.
+            # The absense of this flag means `False`.
+            if room_result.initial:
+                serialized_rooms[room_id]["initial"] = room_result.initial
+
+            # This will omitted for invite/knock rooms with `stripped_state`
+            if room_result.required_state is not None:
+                serialized_required_state = (
+                    await self.event_serializer.serialize_events(
+                        room_result.required_state,
+                        time_now,
+                        config=serialize_options,
+                    )
+                )
+                serialized_rooms[room_id]["required_state"] = serialized_required_state
+
+            # This will omitted for invite/knock rooms with `stripped_state`
+            if room_result.timeline_events is not None:
+                serialized_timeline = await self.event_serializer.serialize_events(
+                    room_result.timeline_events,
+                    time_now,
+                    config=serialize_options,
+                    bundle_aggregations=room_result.bundled_aggregations,
+                )
+                serialized_rooms[room_id]["timeline"] = serialized_timeline
+
+            # This will omitted for invite/knock rooms with `stripped_state`
+            if room_result.limited is not None:
+                serialized_rooms[room_id]["limited"] = room_result.limited
+
+            # This will omitted for invite/knock rooms with `stripped_state`
+            if room_result.prev_batch is not None:
+                serialized_rooms[room_id]["prev_batch"] = (
+                    await room_result.prev_batch.to_string(self.store)
+                )
+
+            # This will omitted for invite/knock rooms with `stripped_state`
+            if room_result.num_live is not None:
+                serialized_rooms[room_id]["num_live"] = room_result.num_live
+
+            # Field should be absent on non-DM rooms
+            if room_result.is_dm:
+                serialized_rooms[room_id]["is_dm"] = room_result.is_dm
+
+            # Stripped state only applies to invite/knock rooms
+            if room_result.stripped_state is not None:
+                # TODO: `knocked_state` but that isn't specced yet.
+                #
+                # TODO: Instead of adding `knocked_state`, it would be good to rename
+                # this to `stripped_state` so it can be shared between invite and knock
+                # rooms, see
+                # https://github.com/matrix-org/matrix-spec-proposals/pull/3575#discussion_r1117629919
+                serialized_rooms[room_id]["invite_state"] = room_result.stripped_state
+
+        return serialized_rooms
+

 def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
    SyncRestServlet(hs).register(http_server)
--- a/synapse/rest/media/download_resource.py
+++ b/synapse/rest/media/download_resource.py
@@ -105,4 +105,5 @@ class DownloadResource(RestServlet):
                file_name,
                max_timeout_ms,
                ip_address,
+                False,
            )
--- a/synapse/storage/controllers/state.py
+++ b/synapse/storage/controllers/state.py
@@ -436,6 +436,9 @@ class StateStorageController:
            )
        )

+        # FIXME: This will return incorrect results when there are timeline gaps. For
+        # example, when you try to get a point in the room we haven't backfilled before.
+
        if last_event_id:
            state = await self.get_state_after_event(
                last_event_id,
--- a/synapse/storage/databases/main/deviceinbox.py
+++ b/synapse/storage/databases/main/deviceinbox.py
@@ -825,14 +825,13 @@ class DeviceInboxWorkerStore(SQLBaseStore):
            # Check if we've already inserted a matching message_id for that
            # origin. This can happen if the origin doesn't receive our
            # acknowledgement from the first time we received the message.
-            already_inserted = self.db_pool.simple_select_one_txn(
+            already_inserted = self.db_pool.simple_select_list_txn(
                txn,
                table="device_federation_inbox",
                keyvalues={"origin": origin, "message_id": message_id},
                retcols=("message_id",),
-                allow_none=True,
            )
-            if already_inserted is not None:
+            if already_inserted:
                return

            # Add an entry for this message_id so that we know we've processed
--- a/synapse/storage/databases/main/events_worker.py
+++ b/synapse/storage/databases/main/events_worker.py
@@ -55,7 +55,7 @@ from synapse.api.room_versions import (
 )
 from synapse.events import EventBase, make_event_from_dict
 from synapse.events.snapshot import EventContext
-from synapse.events.utils import prune_event
+from synapse.events.utils import prune_event, strip_event
 from synapse.logging.context import (
    PreserveLoggingContext,
    current_context,
@@ -1025,15 +1025,7 @@ class EventsWorkerStore(SQLBaseStore):

        state_to_include = await self.get_events(selected_state_ids.values())

-        return [
-            {
-                "type": e.type,
-                "state_key": e.state_key,
-                "content": e.content,
-                "sender": e.sender,
-            }
-            for e in state_to_include.values()
-        ]
+        return [strip_event(e) for e in state_to_include.values()]

    def _maybe_start_fetch_thread(self) -> None:
        """Starts an event fetch thread if we are not yet at the maximum number."""
--- a/synapse/storage/databases/main/stream.py
+++ b/synapse/storage/databases/main/stream.py
@@ -44,6 +44,7 @@ what sort order was used:
 import logging
 from typing import (
    TYPE_CHECKING,
+    AbstractSet,
    Any,
    Collection,
    Dict,
@@ -62,7 +63,7 @@ from typing_extensions import Literal

 from twisted.internet import defer

-from synapse.api.constants import Direction
+from synapse.api.constants import Direction, EventTypes, Membership
 from synapse.api.filtering import Filter
 from synapse.events import EventBase
 from synapse.logging.context import make_deferred_yieldable, run_in_background
@@ -111,6 +112,32 @@ class _EventsAround:
    end: RoomStreamToken


+@attr.s(slots=True, frozen=True, auto_attribs=True)
+class CurrentStateDeltaMembership:
+    """
+    Attributes:
+        event_id: The "current" membership event ID in this room.
+        event_pos: The position of the "current" membership event in the event stream.
+        prev_event_id: The previous membership event in this room that was replaced by
+            the "current" one. May be `None` if there was no previous membership event.
+        room_id: The room ID of the membership event.
+        membership: The membership state of the user in the room
+        sender: The person who sent the membership event
+    """
+
+    room_id: str
+    # Event
+    event_id: Optional[str]
+    event_pos: PersistedEventPosition
+    membership: str
+    sender: Optional[str]
+    # Prev event
+    prev_event_id: Optional[str]
+    prev_event_pos: Optional[PersistedEventPosition]
+    prev_membership: Optional[str]
+    prev_sender: Optional[str]
+
+
 def generate_pagination_where_clause(
    direction: Direction,
    column_names: Tuple[str, str],
@@ -390,6 +417,43 @@ def _filter_results(
    return True


+def _filter_results_by_stream(
+    lower_token: Optional[RoomStreamToken],
+    upper_token: Optional[RoomStreamToken],
+    instance_name: str,
+    stream_ordering: int,
+) -> bool:
+    """
+    This function only works with "live" tokens with `stream_ordering` only. See
+    `_filter_results(...)` if you want to work with all tokens.
+
+    Returns True if the event persisted by the given instance at the given
+    stream_ordering falls between the two tokens (taking a None
+    token to mean unbounded).
+
+    Used to filter results from fetching events in the DB against the given
+    tokens. This is necessary to handle the case where the tokens include
+    position maps, which we handle by fetching more than necessary from the DB
+    and then filtering (rather than attempting to construct a complicated SQL
+    query).
+    """
+    if lower_token:
+        assert lower_token.topological is None
+
+        # If these are live tokens we compare the stream ordering against the
+        # writers stream position.
+        if stream_ordering <= lower_token.get_stream_pos_for_instance(instance_name):
+            return False
+
+    if upper_token:
+        assert upper_token.topological is None
+
+        if upper_token.get_stream_pos_for_instance(instance_name) < stream_ordering:
+            return False
+
+    return True
+
+
 def filter_to_clause(event_filter: Optional[Filter]) -> Tuple[str, List[str]]:
    # NB: This may create SQL clauses that don't optimise well (and we don't
    # have indices on all possible clauses). E.g. it may create
@@ -734,6 +798,191 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):

        return ret, key

+    async def get_current_state_delta_membership_changes_for_user(
+        self,
+        user_id: str,
+        from_key: RoomStreamToken,
+        to_key: RoomStreamToken,
+        excluded_room_ids: Optional[List[str]] = None,
+    ) -> List[CurrentStateDeltaMembership]:
+        """
+        Fetch membership events (and the previous event that was replaced by that one)
+        for a given user.
+
+        Note: This function only works with "live" tokens with `stream_ordering` only.
+
+        We're looking for membership changes in the token range (> `from_key` and <=
+        `to_key`).
+
+        Please be mindful to only use this with `from_key` and `to_key` tokens that are
+        recent enough to be after when the first local user joined the room. Otherwise,
+        the results may be incomplete or too greedy. For example, if you use a token
+        range before the first local user joined the room, you will see 0 events since
+        `current_state_delta_stream` tracks what the server thinks is the current state
+        of the room as time goes. It does not track how state progresses from the
+        beginning of the room. So for example, when you remotely join a room, the first
+        rows will just be the state when you joined and progress from there.
+
+        You can probably reasonably use this with `/sync` because the `to_key` passed in
+        will be the "current" now token and the range will cover when the user joined
+        the room.
+
+        Args:
+            user_id: The user ID to fetch membership events for.
+            from_key: The point in the stream to sync from (fetching events > this point).
+            to_key: The token to fetch rooms up to (fetching events <= this point).
+            excluded_room_ids: Optional list of room IDs to exclude from the results.
+
+        Returns:
+            All membership changes to the current state in the token range. Events are
+            sorted by `stream_ordering` ascending.
+        """
+        # Start by ruling out cases where a DB query is not necessary.
+        if from_key == to_key:
+            return []
+
+        if from_key:
+            has_changed = self._membership_stream_cache.has_entity_changed(
+                user_id, int(from_key.stream)
+            )
+            if not has_changed:
+                return []
+
+        def f(txn: LoggingTransaction) -> List[CurrentStateDeltaMembership]:
+            # To handle tokens with a non-empty instance_map we fetch more
+            # results than necessary and then filter down
+            min_from_id = from_key.stream
+            max_to_id = to_key.get_max_stream_pos()
+
+            args: List[Any] = [min_from_id, max_to_id, EventTypes.Member, user_id]
+
+            # TODO: It would be good to assert that the `from_token`/`to_token` is >=
+            # the first row in `current_state_delta_stream` for the rooms we're
+            # interested in. Otherwise, we will end up with empty results and not know
+            # it.
+
+            # We could `COALESCE(e.stream_ordering, s.stream_id)` to get more accurate
+            # stream positioning when available but given our usages, we can avoid the
+            # complexity. Between two (valid) stream tokens, we will still get all of
+            # the state changes. Since those events are persisted in a batch, valid
+            # tokens will either be before or after the batch of events.
+            #
+            # `stream_ordering` from the `events` table is more accurate when available
+            # since the `current_state_delta_stream` table only tracks that the current
+            # state is at this stream position (not what stream position the state event
+            # was added) and uses the *minimum* stream position for batches of events.
+            sql = """
+                SELECT
+                    s.room_id,
+                    e.event_id,
+                    s.instance_name,
+                    s.stream_id,
+                    m.membership,
+                    e.sender,
+                    s.prev_event_id,
+                    e_prev.instance_name AS prev_instance_name,
+                    e_prev.stream_ordering AS prev_stream_ordering,
+                    m_prev.membership AS prev_membership,
+                    e_prev.sender AS prev_sender
+                FROM current_state_delta_stream AS s
+                    LEFT JOIN events AS e ON e.event_id = s.event_id
+                    LEFT JOIN room_memberships AS m ON m.event_id = s.event_id
+                    LEFT JOIN events AS e_prev ON e_prev.event_id = s.prev_event_id
+                    LEFT JOIN room_memberships AS m_prev ON m_prev.event_id = s.prev_event_id
+                WHERE s.stream_id > ? AND s.stream_id <= ?
+                    AND s.type = ?
+                    AND s.state_key = ?
+                ORDER BY s.stream_id ASC
+            """
+
+            txn.execute(sql, args)
+
+            membership_changes: List[CurrentStateDeltaMembership] = []
+            for (
+                room_id,
+                event_id,
+                instance_name,
+                stream_ordering,
+                membership,
+                sender,
+                prev_event_id,
+                prev_instance_name,
+                prev_stream_ordering,
+                prev_membership,
+                prev_sender,
+            ) in txn:
+                assert room_id is not None
+                assert instance_name is not None
+                assert stream_ordering is not None
+
+                if _filter_results_by_stream(
+                    from_key,
+                    to_key,
+                    instance_name,
+                    stream_ordering,
+                ):
+                    # When the server leaves a room, it will insert new rows into the
+                    # `current_state_delta_stream` table with `event_id = null` for all
+                    # current state. This means we might already have a row for the
+                    # leave event and then another for the same leave where the
+                    # `event_id=null` but the `prev_event_id` is pointing back at the
+                    # earlier leave event. We don't want to report the leave, if we
+                    # already have a leave event.
+                    if event_id is None and prev_membership == Membership.LEAVE:
+                        continue
+
+                    membership_change = CurrentStateDeltaMembership(
+                        room_id=room_id,
+                        # Event
+                        event_id=event_id,
+                        event_pos=PersistedEventPosition(
+                            instance_name=instance_name,
+                            stream=stream_ordering,
+                        ),
+                        # When `s.event_id = null`, we won't be able to get respective
+                        # `room_membership` but can assume the user has left the room
+                        # because this only happens when the server leaves a room
+                        # (meaning everyone locally left) or a state reset which removed
+                        # the person from the room.
+                        membership=(
+                            membership if membership is not None else Membership.LEAVE
+                        ),
+                        sender=sender,
+                        # Prev event
+                        prev_event_id=prev_event_id,
+                        prev_event_pos=(
+                            PersistedEventPosition(
+                                instance_name=prev_instance_name,
+                                stream=prev_stream_ordering,
+                            )
+                            if (
+                                prev_instance_name is not None
+                                and prev_stream_ordering is not None
+                            )
+                            else None
+                        ),
+                        prev_membership=prev_membership,
+                        prev_sender=prev_sender,
+                    )
+
+                    membership_changes.append(membership_change)
+
+            return membership_changes
+
+        membership_changes = await self.db_pool.runInteraction(
+            "get_current_state_delta_membership_changes_for_user", f
+        )
+
+        room_ids_to_exclude: AbstractSet[str] = set()
+        if excluded_room_ids is not None:
+            room_ids_to_exclude = set(excluded_room_ids)
+
+        return [
+            membership_change
+            for membership_change in membership_changes
+            if membership_change.room_id not in room_ids_to_exclude
+        ]
+
    @cancellable
    async def get_membership_changes_for_user(
        self,
@@ -769,10 +1018,11 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):

            ignore_room_clause = ""
            if excluded_rooms is not None and len(excluded_rooms) > 0:
-                ignore_room_clause = "AND e.room_id NOT IN (%s)" % ",".join(
-                    "?" for _ in excluded_rooms
+                ignore_room_clause, ignore_room_args = make_in_list_sql_clause(
+                    txn.database_engine, "e.room_id", excluded_rooms, negative=True
                )
-                args = args + excluded_rooms
+                ignore_room_clause = f"AND {ignore_room_clause}"
+                args += ignore_room_args

            sql = """
                SELECT m.event_id, instance_name, topological_ordering, stream_ordering
@@ -1554,6 +1804,9 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
    ) -> Tuple[List[EventBase], RoomStreamToken]:
        """Returns list of events before or after a given token.

+        When Direction.FORWARDS: from_key < x <= to_key
+        When Direction.BACKWARDS: from_key >= x > to_key
+
        Args:
            room_id
            from_key: The token used to stream from
@@ -1570,6 +1823,27 @@ class StreamWorkerStore(EventsWorkerStore, SQLBaseStore):
            and `to_key`).
        """

+        # We can bail early if we're looking forwards, and our `to_key` is already
+        # before our `from_key`.
+        if (
+            direction == Direction.FORWARDS
+            and to_key is not None
+            and to_key.is_before_or_eq(from_key)
+        ):
+            # Token selection matches what we do in `_paginate_room_events_txn` if there
+            # are no rows
+            return [], to_key if to_key else from_key
+        # Or vice-versa, if we're looking backwards and our `from_key` is already before
+        # our `to_key`.
+        elif (
+            direction == Direction.BACKWARDS
+            and to_key is not None
+            and from_key.is_before_or_eq(to_key)
+        ):
+            # Token selection matches what we do in `_paginate_room_events_txn` if there
+            # are no rows
+            return [], to_key if to_key else from_key
+
        rows, token = await self.db_pool.runInteraction(
            "paginate_room_events",
            self._paginate_room_events_txn,
--- a/synapse/storage/schema/main/delta/42/current_state_delta.sql
+++ b/synapse/storage/schema/main/delta/42/current_state_delta.sql
@@ -32,7 +32,10 @@
 * limitations under the License.
 */

-
+-- Tracks what the server thinks is the current state of the room as time goes. It does
+-- not track how state progresses from the beginning of the room. So for example, when
+-- you remotely join a room, the first rows will just be the state when you joined and
+-- progress from there.
 CREATE TABLE current_state_delta_stream (
    stream_id BIGINT NOT NULL,
    room_id TEXT NOT NULL,
--- a/synapse/types/init.py
+++ b/synapse/types/init.py
@@ -1096,6 +1096,9 @@ class PersistedPosition:
    stream: int

    def persisted_after(self, token: AbstractMultiWriterStreamToken) -> bool:
+        """
+        Checks whether this position happened after the token
+        """
        return token.get_stream_pos_for_instance(self.instance_name) < self.stream


--- a/synapse/types/handlers/init.py
+++ b/synapse/types/handlers/init.py
@@ -31,9 +31,12 @@ else:
    from pydantic import Extra

 from synapse.events import EventBase
-from synapse.types import JsonMapping, StreamToken, UserID
+from synapse.types import JsonDict, JsonMapping, StreamToken, UserID
 from synapse.types.rest.client import SlidingSyncBody

+if TYPE_CHECKING:
+    from synapse.handlers.relations import BundledAggregations
+

 class ShutdownRoomParams(TypedDict):
    """
@@ -159,11 +162,16 @@ class SlidingSyncResult:
                entirely and NOT send "initial":false as this is wasteful on bandwidth. The
                absence of this flag means 'false'.
            required_state: The current state of the room
-            timeline: Latest events in the room. The last event is the most recent
+            timeline: Latest events in the room. The last event is the most recent.
+            bundled_aggregations: A mapping of event ID to the bundled aggregations for
+                the timeline events above. This allows clients to show accurate reaction
+                counts (or edits, threads), even if some of the reaction events were skipped
+                over in a gappy sync.
            is_dm: Flag to specify whether the room is a direct-message room (most likely
                between two people).
-            invite_state: Stripped state events. Same as `rooms.invite.$room_id.invite_state`
-                in sync v2, absent on joined/left rooms
+            stripped_state: Stripped state events (for rooms where the usre is
+                invited/knocked). Same as `rooms.invite.$room_id.invite_state` in sync v2,
+                absent on joined/left rooms
            prev_batch: A token that can be passed as a start parameter to the
                `/rooms/<room_id>/messages` API to retrieve earlier messages.
            limited: True if their are more events than fit between the given position and now.
@@ -185,21 +193,28 @@ class SlidingSyncResult:
                (with potentially other old events in the timeline).
        """

-        name: str
+        name: Optional[str]
        avatar: Optional[str]
        heroes: Optional[List[EventBase]]
        initial: bool
-        required_state: List[EventBase]
-        timeline: List[EventBase]
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        required_state: Optional[List[EventBase]]
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        timeline_events: Optional[List[EventBase]]
+        bundled_aggregations: Optional[Dict[str, "BundledAggregations"]]
        is_dm: bool
-        invite_state: List[EventBase]
-        prev_batch: StreamToken
-        limited: bool
+        # Optional because it's only relevant to invite/knock rooms
+        stripped_state: Optional[List[JsonDict]]
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        prev_batch: Optional[StreamToken]
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        limited: Optional[bool]
        joined_count: int
        invited_count: int
        notification_count: int
        highlight_count: int
-        num_live: int
+        # Only optional because it won't be included for invite/knock rooms with `stripped_state`
+        num_live: Optional[int]

    @attr.s(slots=True, frozen=True, auto_attribs=True)
    class SlidingWindowList:
--- a/synapse/types/rest/client/init.py
+++ b/synapse/types/rest/client/init.py
@@ -152,22 +152,14 @@ class SlidingSyncBody(RequestBodyModel):
                anyway.
            timeline_limit: The maximum number of timeline events to return per response.
                (Max 1000 messages)
-            include_old_rooms: Determines if `predecessor` rooms are included in the
-                `rooms` response. The user MUST be joined to old rooms for them to show up
-                in the response.
        """

-        class IncludeOldRooms(RequestBodyModel):
-            timeline_limit: StrictInt
-            required_state: List[Tuple[StrictStr, StrictStr]]
-
        required_state: List[Tuple[StrictStr, StrictStr]]
        # mypy workaround via https://github.com/pydantic/pydantic/issues/156#issuecomment-1130883884
        if TYPE_CHECKING:
            timeline_limit: int
        else:
            timeline_limit: conint(le=1000, strict=True)  # type: ignore[valid-type]
-        include_old_rooms: Optional[IncludeOldRooms] = None

    class SlidingSyncList(CommonRoomParameters):
        """
@@ -208,9 +200,6 @@ class SlidingSyncBody(RequestBodyModel):
                    }

            timeline_limit: The maximum number of timeline events to return per response.
-            include_old_rooms: Determines if `predecessor` rooms are included in the
-                `rooms` response. The user MUST be joined to old rooms for them to show up
-                in the response.
            include_heroes: Return a stripped variant of membership events (containing
                `user_id` and optionally `avatar_url` and `displayname`) for the users used
                to calculate the room name.
@@ -270,7 +259,7 @@ class SlidingSyncBody(RequestBodyModel):
            is_encrypted: Optional[StrictBool] = None
            is_invite: Optional[StrictBool] = None
            room_types: Optional[List[Union[StrictStr, None]]] = None
-            not_room_types: Optional[List[StrictStr]] = None
+            not_room_types: Optional[List[Union[StrictStr, None]]] = None
            room_name_like: Optional[StrictStr] = None
            tags: Optional[List[StrictStr]] = None
            not_tags: Optional[List[StrictStr]] = None
--- a/tests/federation/test_federation_media.py
+++ b/tests/federation/test_federation_media.py
@@ -36,10 +36,9 @@ from synapse.util import Clock

 from tests import unittest
 from tests.test_utils import SMALL_PNG
-from tests.unittest import override_config


-class FederationUnstableMediaDownloadsTest(unittest.FederatingHomeserverTestCase):
+class FederationMediaDownloadsTest(unittest.FederatingHomeserverTestCase):

    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
        super().prepare(reactor, clock, hs)
@@ -65,9 +64,6 @@ class FederationUnstableMediaDownloadsTest(unittest.FederatingHomeserverTestCase
        )
        self.media_repo = hs.get_media_repository()

-    @override_config(
-        {"experimental_features": {"msc3916_authenticated_media_enabled": True}}
-    )
    def test_file_download(self) -> None:
        content = io.BytesIO(b"file_to_stream")
        content_uri = self.get_success(
@@ -82,7 +78,7 @@ class FederationUnstableMediaDownloadsTest(unittest.FederatingHomeserverTestCase
        # test with a text file
        channel = self.make_signed_federation_request(
            "GET",
-            f"/_matrix/federation/unstable/org.matrix.msc3916/media/download/{content_uri.media_id}",
+            f"/_matrix/federation/v1/media/download/{content_uri.media_id}",
        )
        self.pump()
        self.assertEqual(200, channel.code)
@@ -106,7 +102,8 @@ class FederationUnstableMediaDownloadsTest(unittest.FederatingHomeserverTestCase

        # check that the text file and expected value exist
        found_file = any(
-            "\r\nContent-Type: text/plain\r\n\r\nfile_to_stream" in field
+            "\r\nContent-Type: text/plain\r\nContent-Disposition: inline; filename=test_upload\r\n\r\nfile_to_stream"
+            in field
            for field in stripped
        )
        self.assertTrue(found_file)
@@ -124,7 +121,7 @@ class FederationUnstableMediaDownloadsTest(unittest.FederatingHomeserverTestCase
        # test with an image file
        channel = self.make_signed_federation_request(
            "GET",
-            f"/_matrix/federation/unstable/org.matrix.msc3916/media/download/{content_uri.media_id}",
+            f"/_matrix/federation/v1/media/download/{content_uri.media_id}",
        )
        self.pump()
        self.assertEqual(200, channel.code)
@@ -149,25 +146,3 @@ class FederationUnstableMediaDownloadsTest(unittest.FederatingHomeserverTestCase
        # check that the png file exists and matches what was uploaded
        found_file = any(SMALL_PNG in field for field in stripped_bytes)
        self.assertTrue(found_file)
-
-    @override_config(
-        {"experimental_features": {"msc3916_authenticated_media_enabled": False}}
-    )
-    def test_disable_config(self) -> None:
-        content = io.BytesIO(b"file_to_stream")
-        content_uri = self.get_success(
-            self.media_repo.create_content(
-                "text/plain",
-                "test_upload",
-                content,
-                46,
-                UserID.from_string("@user_id:whatever.org"),
-            )
-        )
-        channel = self.make_signed_federation_request(
-            "GET",
-            f"/_matrix/federation/unstable/org.matrix.msc3916/media/download/{content_uri.media_id}",
-        )
-        self.pump()
-        self.assertEqual(404, channel.code)
-        self.assertEqual(channel.json_body.get("errcode"), "M_UNRECOGNIZED")
--- a/tests/handlers/test_sliding_sync.py
+++ b/tests/handlers/test_sliding_sync.py
--- a/tests/http/test_client.py
+++ b/tests/http/test_client.py
@@ -37,18 +37,155 @@ from synapse.http.client import (
    BlocklistingAgentWrapper,
    BlocklistingReactorWrapper,
    BodyExceededMaxSize,
+    MultipartResponse,
    _DiscardBodyWithMaxSizeProtocol,
+    _MultipartParserProtocol,
    read_body_with_max_size,
+    read_multipart_response,
 )

 from tests.server import FakeTransport, get_clock
 from tests.unittest import TestCase


+class ReadMultipartResponseTests(TestCase):
+    data1 = b"\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: application/json\r\n\r\n{}\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: text/plain\r\nContent-Disposition: inline; filename=test_upload\r\n\r\nfile_"
+    data2 = b"to_stream\r\n--6067d4698f8d40a0a794ea7d7379d53a--\r\n\r\n"
+
+    redirect_data = b"\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: application/json\r\n\r\n{}\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nLocation: https://cdn.example.org/ab/c1/2345.txt\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a--\r\n\r\n"
+
+    def _build_multipart_response(
+        self, response_length: Union[int, str], max_length: int
+    ) -> Tuple[
+        BytesIO,
+        "Deferred[MultipartResponse]",
+        _MultipartParserProtocol,
+    ]:
+        """Start reading the body, returns the response, result and proto"""
+        response = Mock(length=response_length)
+        result = BytesIO()
+        boundary = "6067d4698f8d40a0a794ea7d7379d53a"
+        deferred = read_multipart_response(response, result, boundary, max_length)
+
+        # Fish the protocol out of the response.
+        protocol = response.deliverBody.call_args[0][0]
+        protocol.transport = Mock()
+
+        return result, deferred, protocol
+
+    def _assert_error(
+        self,
+        deferred: "Deferred[MultipartResponse]",
+        protocol: _MultipartParserProtocol,
+    ) -> None:
+        """Ensure that the expected error is received."""
+        assert isinstance(deferred.result, Failure)
+        self.assertIsInstance(deferred.result.value, BodyExceededMaxSize)
+        assert protocol.transport is not None
+        # type-ignore: presumably abortConnection has been replaced with a Mock.
+        protocol.transport.abortConnection.assert_called_once()  # type: ignore[attr-defined]
+
+    def _cleanup_error(self, deferred: "Deferred[MultipartResponse]") -> None:
+        """Ensure that the error in the Deferred is handled gracefully."""
+        called = [False]
+
+        def errback(f: Failure) -> None:
+            called[0] = True
+
+        deferred.addErrback(errback)
+        self.assertTrue(called[0])
+
+    def test_parse_file(self) -> None:
+        """
+        Check that a multipart response containing a file is properly parsed
+        into the json/file parts, and the json and file are properly captured
+        """
+        result, deferred, protocol = self._build_multipart_response(249, 250)
+
+        # Start sending data.
+        protocol.dataReceived(self.data1)
+        protocol.dataReceived(self.data2)
+        # Close the connection.
+        protocol.connectionLost(Failure(ResponseDone()))
+
+        multipart_response: MultipartResponse = deferred.result  # type: ignore[assignment]
+
+        self.assertEqual(multipart_response.json, b"{}")
+        self.assertEqual(result.getvalue(), b"file_to_stream")
+        self.assertEqual(multipart_response.length, len(b"file_to_stream"))
+        self.assertEqual(multipart_response.content_type, b"text/plain")
+        self.assertEqual(
+            multipart_response.disposition, b"inline; filename=test_upload"
+        )
+
+    def test_parse_redirect(self) -> None:
+        """
+        check that a multipart response containing a redirect is properly parsed and redirect url is
+        returned
+        """
+        result, deferred, protocol = self._build_multipart_response(249, 250)
+
+        # Start sending data.
+        protocol.dataReceived(self.redirect_data)
+        # Close the connection.
+        protocol.connectionLost(Failure(ResponseDone()))
+
+        multipart_response: MultipartResponse = deferred.result  # type: ignore[assignment]
+
+        self.assertEqual(multipart_response.json, b"{}")
+        self.assertEqual(result.getvalue(), b"")
+        self.assertEqual(
+            multipart_response.url, b"https://cdn.example.org/ab/c1/2345.txt"
+        )
+
+    def test_too_large(self) -> None:
+        """A response which is too large raises an exception."""
+        result, deferred, protocol = self._build_multipart_response(UNKNOWN_LENGTH, 180)
+
+        # Start sending data.
+        protocol.dataReceived(self.data1)
+
+        self.assertEqual(result.getvalue(), b"file_")
+        self._assert_error(deferred, protocol)
+        self._cleanup_error(deferred)
+
+    def test_additional_data(self) -> None:
+        """A connection can receive data after being closed."""
+        result, deferred, protocol = self._build_multipart_response(UNKNOWN_LENGTH, 180)
+
+        # Start sending data.
+        protocol.dataReceived(self.data1)
+        self._assert_error(deferred, protocol)
+
+        # More data might have come in.
+        protocol.dataReceived(self.data2)
+
+        self.assertEqual(result.getvalue(), b"file_")
+        self._assert_error(deferred, protocol)
+        self._cleanup_error(deferred)
+
+    def test_content_length(self) -> None:
+        """The body shouldn't be read (at all) if the Content-Length header is too large."""
+        result, deferred, protocol = self._build_multipart_response(250, 1)
+
+        # Deferred shouldn't be called yet.
+        self.assertFalse(deferred.called)
+
+        # Start sending data.
+        protocol.dataReceived(self.data1)
+        self._assert_error(deferred, protocol)
+        self._cleanup_error(deferred)
+
+        # The data is never consumed.
+        self.assertEqual(result.getvalue(), b"")
+
+
 class ReadBodyWithMaxSizeTests(TestCase):
-    def _build_response(
-        self, length: Union[int, str] = UNKNOWN_LENGTH
-    ) -> Tuple[BytesIO, "Deferred[int]", _DiscardBodyWithMaxSizeProtocol]:
+    def _build_response(self, length: Union[int, str] = UNKNOWN_LENGTH) -> Tuple[
+        BytesIO,
+        "Deferred[int]",
+        _DiscardBodyWithMaxSizeProtocol,
+    ]:
        """Start reading the body, returns the response, result and proto"""
        response = Mock(length=length)
        result = BytesIO()
--- a/tests/media/test_media_storage.py
+++ b/tests/media/test_media_storage.py
@@ -129,7 +129,7 @@ class MediaStorageTests(unittest.HomeserverTestCase):


@attr.s(auto_attribs=True, slots=True, frozen=True)
-class _TestImage:
+class TestImage:
    """An image for testing thumbnailing with the expected results

    Attributes:
@@ -158,7 +158,7 @@ class _TestImage:
    is_inline: bool = True


-small_png = _TestImage(
+small_png = TestImage(
    SMALL_PNG,
    b"image/png",
    b".png",
@@ -175,7 +175,7 @@ small_png = _TestImage(
    ),
 )

-small_png_with_transparency = _TestImage(
+small_png_with_transparency = TestImage(
    unhexlify(
        b"89504e470d0a1a0a0000000d49484452000000010000000101000"
        b"00000376ef9240000000274524e5300010194fdae0000000a4944"
@@ -188,7 +188,7 @@ small_png_with_transparency = _TestImage(
    # different versions of Pillow.
 )

-small_lossless_webp = _TestImage(
+small_lossless_webp = TestImage(
    unhexlify(
        b"524946461a000000574542505650384c0d0000002f0000001007" b"1011118888fe0700"
    ),
@@ -196,7 +196,7 @@ small_lossless_webp = _TestImage(
    b".webp",
 )

-empty_file = _TestImage(
+empty_file = TestImage(
    b"",
    b"image/gif",
    b".gif",
@@ -204,7 +204,7 @@ empty_file = _TestImage(
    unable_to_thumbnail=True,
 )

-SVG = _TestImage(
+SVG = TestImage(
    b"""<?xml version="1.0"?>
 <!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN"
  "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">
@@ -236,7 +236,7 @@ urls = [
@parameterized_class(("test_image", "url"), itertools.product(test_images, urls))
 class MediaRepoTests(unittest.HomeserverTestCase):
    servlets = [media.register_servlets]
-    test_image: ClassVar[_TestImage]
+    test_image: ClassVar[TestImage]
    hijack_auth = True
    user_id = "@test:user"
    url: ClassVar[str]
--- a/tests/replication/test_multi_media_repo.py
+++ b/tests/replication/test_multi_media_repo.py
@@ -28,7 +28,7 @@ from twisted.web.http import HTTPChannel
 from twisted.web.server import Request

 from synapse.rest import admin
-from synapse.rest.client import login
+from synapse.rest.client import login, media
 from synapse.server import HomeServer
 from synapse.util import Clock

@@ -255,6 +255,238 @@ class MediaRepoShardTestCase(BaseMultiWorkerStreamTestCase):
        return sum(len(files) for _, _, files in os.walk(path))


+class AuthenticatedMediaRepoShardTestCase(BaseMultiWorkerStreamTestCase):
+    """Checks running multiple media repos work correctly using autheticated media paths"""
+
+    servlets = [
+        admin.register_servlets_for_client_rest_resource,
+        login.register_servlets,
+        media.register_servlets,
+    ]
+
+    file_data = b"\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: application/json\r\n\r\n{}\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: text/plain\r\nContent-Disposition: inline; filename=test_upload\r\n\r\nfile_to_stream\r\n--6067d4698f8d40a0a794ea7d7379d53a--\r\n\r\n"
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.user_id = self.register_user("user", "pass")
+        self.access_token = self.login("user", "pass")
+
+        self.reactor.lookups["example.com"] = "1.2.3.4"
+
+    def default_config(self) -> dict:
+        conf = super().default_config()
+        conf["federation_custom_ca_list"] = [get_test_ca_cert_file()]
+        return conf
+
+    def make_worker_hs(
+        self, worker_app: str, extra_config: Optional[dict] = None, **kwargs: Any
+    ) -> HomeServer:
+        worker_hs = super().make_worker_hs(worker_app, extra_config, **kwargs)
+        # Force the media paths onto the replication resource.
+        worker_hs.get_media_repository_resource().register_servlets(
+            self._hs_to_site[worker_hs].resource, worker_hs
+        )
+        return worker_hs
+
+    def _get_media_req(
+        self, hs: HomeServer, target: str, media_id: str
+    ) -> Tuple[FakeChannel, Request]:
+        """Request some remote media from the given HS by calling the download
+        API.
+
+        This then triggers an outbound request from the HS to the target.
+
+        Returns:
+            The channel for the *client* request and the *outbound* request for
+            the media which the caller should respond to.
+        """
+        channel = make_request(
+            self.reactor,
+            self._hs_to_site[hs],
+            "GET",
+            f"/_matrix/client/v1/media/download/{target}/{media_id}",
+            shorthand=False,
+            access_token=self.access_token,
+            await_result=False,
+        )
+        self.pump()
+
+        clients = self.reactor.tcpClients
+        self.assertGreaterEqual(len(clients), 1)
+        (host, port, client_factory, _timeout, _bindAddress) = clients.pop()
+
+        # build the test server
+        server_factory = Factory.forProtocol(HTTPChannel)
+        # Request.finish expects the factory to have a 'log' method.
+        server_factory.log = _log_request
+
+        server_tls_protocol = wrap_server_factory_for_tls(
+            server_factory, self.reactor, sanlist=[b"DNS:example.com"]
+        ).buildProtocol(None)
+
+        # now, tell the client protocol factory to build the client protocol (it will be a
+        # _WrappingProtocol, around a TLSMemoryBIOProtocol, around an
+        # HTTP11ClientProtocol) and wire the output of said protocol up to the server via
+        # a FakeTransport.
+        #
+        # Normally this would be done by the TCP socket code in Twisted, but we are
+        # stubbing that out here.
+        client_protocol = client_factory.buildProtocol(None)
+        client_protocol.makeConnection(
+            FakeTransport(server_tls_protocol, self.reactor, client_protocol)
+        )
+
+        # tell the server tls protocol to send its stuff back to the client, too
+        server_tls_protocol.makeConnection(
+            FakeTransport(client_protocol, self.reactor, server_tls_protocol)
+        )
+
+        # fish the test server back out of the server-side TLS protocol.
+        http_server: HTTPChannel = server_tls_protocol.wrappedProtocol
+
+        # give the reactor a pump to get the TLS juices flowing.
+        self.reactor.pump((0.1,))
+
+        self.assertEqual(len(http_server.requests), 1)
+        request = http_server.requests[0]
+
+        self.assertEqual(request.method, b"GET")
+        self.assertEqual(
+            request.path,
+            f"/_matrix/federation/v1/media/download/{media_id}".encode(),
+        )
+        self.assertEqual(
+            request.requestHeaders.getRawHeaders(b"host"), [target.encode("utf-8")]
+        )
+
+        return channel, request
+
+    def test_basic(self) -> None:
+        """Test basic fetching of remote media from a single worker."""
+        hs1 = self.make_worker_hs("synapse.app.generic_worker")
+
+        channel, request = self._get_media_req(hs1, "example.com:443", "ABC123")
+
+        request.setResponseCode(200)
+        request.responseHeaders.setRawHeaders(
+            b"Content-Type",
+            ["multipart/mixed; boundary=6067d4698f8d40a0a794ea7d7379d53a"],
+        )
+        request.write(self.file_data)
+        request.finish()
+
+        self.pump(0.1)
+
+        self.assertEqual(channel.code, 200)
+        self.assertEqual(channel.result["body"], b"file_to_stream")
+
+    def test_download_simple_file_race(self) -> None:
+        """Test that fetching remote media from two different processes at the
+        same time works.
+        """
+        hs1 = self.make_worker_hs("synapse.app.generic_worker")
+        hs2 = self.make_worker_hs("synapse.app.generic_worker")
+
+        start_count = self._count_remote_media()
+
+        # Make two requests without responding to the outbound media requests.
+        channel1, request1 = self._get_media_req(hs1, "example.com:443", "ABC123")
+        channel2, request2 = self._get_media_req(hs2, "example.com:443", "ABC123")
+
+        # Respond to the first outbound media request and check that the client
+        # request is successful
+        request1.setResponseCode(200)
+        request1.responseHeaders.setRawHeaders(
+            b"Content-Type",
+            ["multipart/mixed; boundary=6067d4698f8d40a0a794ea7d7379d53a"],
+        )
+        request1.write(self.file_data)
+        request1.finish()
+
+        self.pump(0.1)
+
+        self.assertEqual(channel1.code, 200, channel1.result["body"])
+        self.assertEqual(channel1.result["body"], b"file_to_stream")
+
+        # Now respond to the second with the same content.
+        request2.setResponseCode(200)
+        request2.responseHeaders.setRawHeaders(
+            b"Content-Type",
+            ["multipart/mixed; boundary=6067d4698f8d40a0a794ea7d7379d53a"],
+        )
+        request2.write(self.file_data)
+        request2.finish()
+
+        self.pump(0.1)
+
+        self.assertEqual(channel2.code, 200, channel2.result["body"])
+        self.assertEqual(channel2.result["body"], b"file_to_stream")
+
+        # We expect only one new file to have been persisted.
+        self.assertEqual(start_count + 1, self._count_remote_media())
+
+    def test_download_image_race(self) -> None:
+        """Test that fetching remote *images* from two different processes at
+        the same time works.
+
+        This checks that races generating thumbnails are handled correctly.
+        """
+        hs1 = self.make_worker_hs("synapse.app.generic_worker")
+        hs2 = self.make_worker_hs("synapse.app.generic_worker")
+
+        start_count = self._count_remote_thumbnails()
+
+        channel1, request1 = self._get_media_req(hs1, "example.com:443", "PIC1")
+        channel2, request2 = self._get_media_req(hs2, "example.com:443", "PIC1")
+
+        request1.setResponseCode(200)
+        request1.responseHeaders.setRawHeaders(
+            b"Content-Type",
+            ["multipart/mixed; boundary=6067d4698f8d40a0a794ea7d7379d53a"],
+        )
+        img_data = b"\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: application/json\r\n\r\n{}\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: image/png\r\nContent-Disposition: inline; filename=test_img\r\n\r\n"
+        request1.write(img_data)
+        request1.write(SMALL_PNG)
+        request1.write(b"\r\n--6067d4698f8d40a0a794ea7d7379d53a--\r\n\r\n")
+        request1.finish()
+
+        self.pump(0.1)
+
+        self.assertEqual(channel1.code, 200, channel1.result["body"])
+        self.assertEqual(channel1.result["body"], SMALL_PNG)
+
+        request2.setResponseCode(200)
+        request2.responseHeaders.setRawHeaders(
+            b"Content-Type",
+            ["multipart/mixed; boundary=6067d4698f8d40a0a794ea7d7379d53a"],
+        )
+        request2.write(img_data)
+        request2.write(SMALL_PNG)
+        request2.write(b"\r\n--6067d4698f8d40a0a794ea7d7379d53a--\r\n\r\n")
+        request2.finish()
+
+        self.pump(0.1)
+
+        self.assertEqual(channel2.code, 200, channel2.result["body"])
+        self.assertEqual(channel2.result["body"], SMALL_PNG)
+
+        # We expect only three new thumbnails to have been persisted.
+        self.assertEqual(start_count + 3, self._count_remote_thumbnails())
+
+    def _count_remote_media(self) -> int:
+        """Count the number of files in our remote media directory."""
+        path = os.path.join(
+            self.hs.get_media_repository().primary_base_path, "remote_content"
+        )
+        return sum(len(files) for _, _, files in os.walk(path))
+
+    def _count_remote_thumbnails(self) -> int:
+        """Count the number of files in our remote thumbnails directory."""
+        path = os.path.join(
+            self.hs.get_media_repository().primary_base_path, "remote_thumbnail"
+        )
+        return sum(len(files) for _, _, files in os.walk(path))
+
+
 def _log_request(request: Request) -> None:
    """Implements Factory.log, which is expected by Request.finish"""
    logger.info("Completed request %s", request)
--- a/tests/rest/client/test_media.py
+++ b/tests/rest/client/test_media.py
@@ -19,31 +19,54 @@
 #
 #
 import base64
+import io
 import json
 import os
 import re
-from typing import Any, Dict, Optional, Sequence, Tuple, Type
+from typing import Any, BinaryIO, ClassVar, Dict, List, Optional, Sequence, Tuple, Type
+from unittest.mock import MagicMock, Mock, patch
+from urllib import parse
 from urllib.parse import quote, urlencode

+from parameterized import parameterized_class
+
+from twisted.internet import defer
 from twisted.internet._resolver import HostResolution
 from twisted.internet.address import IPv4Address, IPv6Address
+from twisted.internet.defer import Deferred
 from twisted.internet.error import DNSLookupError
 from twisted.internet.interfaces import IAddress, IResolutionReceiver
+from twisted.python.failure import Failure
 from twisted.test.proto_helpers import AccumulatingProtocol, MemoryReactor
+from twisted.web.http_headers import Headers
+from twisted.web.iweb import UNKNOWN_LENGTH, IResponse
 from twisted.web.resource import Resource

+from synapse.api.errors import HttpResponseException
+from synapse.api.ratelimiting import Ratelimiter
 from synapse.config.oembed import OEmbedEndpointConfig
+from synapse.http.client import MultipartResponse
+from synapse.http.types import QueryParams
+from synapse.logging.context import make_deferred_yieldable
 from synapse.media._base import FileInfo
 from synapse.media.url_previewer import IMAGE_CACHE_EXPIRY_MS
 from synapse.rest import admin
 from synapse.rest.client import login, media
 from synapse.server import HomeServer
-from synapse.types import JsonDict
+from synapse.types import JsonDict, UserID
 from synapse.util import Clock
 from synapse.util.stringutils import parse_and_validate_mxc_uri

 from tests import unittest
-from tests.server import FakeTransport, ThreadedMemoryReactorClock
+from tests.media.test_media_storage import (
+    SVG,
+    TestImage,
+    empty_file,
+    small_lossless_webp,
+    small_png,
+    small_png_with_transparency,
+)
+from tests.server import FakeChannel, FakeTransport, ThreadedMemoryReactorClock
 from tests.test_utils import SMALL_PNG
 from tests.unittest import override_config

@@ -1607,3 +1630,583 @@ class UnstableMediaConfigTest(unittest.HomeserverTestCase):
        self.assertEqual(
            channel.json_body["m.upload.size"], self.hs.config.media.max_upload_size
        )
+
+
+class RemoteDownloadLimiterTestCase(unittest.HomeserverTestCase):
+    servlets = [
+        media.register_servlets,
+        login.register_servlets,
+        admin.register_servlets,
+    ]
+
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
+        config = self.default_config()
+
+        self.storage_path = self.mktemp()
+        self.media_store_path = self.mktemp()
+        os.mkdir(self.storage_path)
+        os.mkdir(self.media_store_path)
+        config["media_store_path"] = self.media_store_path
+
+        provider_config = {
+            "module": "synapse.media.storage_provider.FileStorageProviderBackend",
+            "store_local": True,
+            "store_synchronous": False,
+            "store_remote": True,
+            "config": {"directory": self.storage_path},
+        }
+
+        config["media_storage_providers"] = [provider_config]
+
+        return self.setup_test_homeserver(config=config)
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.repo = hs.get_media_repository()
+        self.client = hs.get_federation_http_client()
+        self.store = hs.get_datastores().main
+        self.user = self.register_user("user", "pass")
+        self.tok = self.login("user", "pass")
+
+    # mock actually reading file body
+    def read_multipart_response_30MiB(*args: Any, **kwargs: Any) -> Deferred:
+        d: Deferred = defer.Deferred()
+        d.callback(MultipartResponse(b"{}", 31457280, b"img/png", None))
+        return d
+
+    def read_multipart_response_50MiB(*args: Any, **kwargs: Any) -> Deferred:
+        d: Deferred = defer.Deferred()
+        d.callback(MultipartResponse(b"{}", 31457280, b"img/png", None))
+        return d
+
+    @patch(
+        "synapse.http.matrixfederationclient.read_multipart_response",
+        read_multipart_response_30MiB,
+    )
+    def test_download_ratelimit_default(self) -> None:
+        """
+        Test remote media download ratelimiting against default configuration - 500MB bucket
+        and 87kb/second drain rate
+        """
+
+        # mock out actually sending the request, returns a 30MiB response
+        async def _send_request(*args: Any, **kwargs: Any) -> IResponse:
+            resp = MagicMock(spec=IResponse)
+            resp.code = 200
+            resp.length = 31457280
+            resp.headers = Headers(
+                {"Content-Type": ["multipart/mixed; boundary=gc0p4Jq0M2Yt08jU534c0p"]}
+            )
+            resp.phrase = b"OK"
+            return resp
+
+        self.client._send_request = _send_request  # type: ignore
+
+        # first request should go through
+        channel = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abc",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel.code == 200
+
+        # next 15 should go through
+        for i in range(15):
+            channel2 = self.make_request(
+                "GET",
+                f"/_matrix/client/v1/media/download/remote.org/abc{i}",
+                shorthand=False,
+                access_token=self.tok,
+            )
+            assert channel2.code == 200
+
+        # 17th will hit ratelimit
+        channel3 = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abcd",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel3.code == 429
+
+        # however, a request from a different IP will go through
+        channel4 = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abcde",
+            shorthand=False,
+            client_ip="187.233.230.159",
+            access_token=self.tok,
+        )
+        assert channel4.code == 200
+
+        # at 87Kib/s it should take about 2 minutes for enough to drain from bucket that another
+        # 30MiB download is authorized - The last download was blocked at 503,316,480.
+        # The next download will be authorized when bucket hits 492,830,720
+        # (524,288,000 total capacity - 31,457,280 download size) so 503,316,480 - 492,830,720 ~= 10,485,760
+        # needs to drain before another download will be authorized, that will take ~=
+        # 2 minutes (10,485,760/89,088/60)
+        self.reactor.pump([2.0 * 60.0])
+
+        # enough has drained and next request goes through
+        channel5 = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abcdef",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel5.code == 200
+
+    @override_config(
+        {
+            "remote_media_download_per_second": "50M",
+            "remote_media_download_burst_count": "50M",
+        }
+    )
+    @patch(
+        "synapse.http.matrixfederationclient.read_multipart_response",
+        read_multipart_response_50MiB,
+    )
+    def test_download_rate_limit_config(self) -> None:
+        """
+        Test that download rate limit config options are correctly picked up and applied
+        """
+
+        async def _send_request(*args: Any, **kwargs: Any) -> IResponse:
+            resp = MagicMock(spec=IResponse)
+            resp.code = 200
+            resp.length = 52428800
+            resp.headers = Headers(
+                {"Content-Type": ["multipart/mixed; boundary=gc0p4Jq0M2Yt08jU534c0p"]}
+            )
+            resp.phrase = b"OK"
+            return resp
+
+        self.client._send_request = _send_request  # type: ignore
+
+        # first request should go through
+        channel = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abc",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel.code == 200
+
+        # immediate second request should fail
+        channel = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abcd",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel.code == 429
+
+        # advance half a second
+        self.reactor.pump([0.5])
+
+        # request still fails
+        channel = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abcde",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel.code == 429
+
+        # advance another half second
+        self.reactor.pump([0.5])
+
+        # enough has drained from bucket and request is successful
+        channel = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abcdef",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel.code == 200
+
+    @patch(
+        "synapse.http.matrixfederationclient.read_multipart_response",
+        read_multipart_response_30MiB,
+    )
+    def test_download_ratelimit_max_size_sub(self) -> None:
+        """
+        Test that if no content-length is provided, the default max size is applied instead
+        """
+
+        # mock out actually sending the request
+        async def _send_request(*args: Any, **kwargs: Any) -> IResponse:
+            resp = MagicMock(spec=IResponse)
+            resp.code = 200
+            resp.length = UNKNOWN_LENGTH
+            resp.headers = Headers(
+                {"Content-Type": ["multipart/mixed; boundary=gc0p4Jq0M2Yt08jU534c0p"]}
+            )
+            resp.phrase = b"OK"
+            return resp
+
+        self.client._send_request = _send_request  # type: ignore
+
+        # ten requests should go through using the max size (500MB/50MB)
+        for i in range(10):
+            channel2 = self.make_request(
+                "GET",
+                f"/_matrix/client/v1/media/download/remote.org/abc{i}",
+                shorthand=False,
+                access_token=self.tok,
+            )
+            assert channel2.code == 200
+
+        # eleventh will hit ratelimit
+        channel3 = self.make_request(
+            "GET",
+            "/_matrix/client/v1/media/download/remote.org/abcd",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        assert channel3.code == 429
+
+    def test_file_download(self) -> None:
+        content = io.BytesIO(b"file_to_stream")
+        content_uri = self.get_success(
+            self.repo.create_content(
+                "text/plain",
+                "test_upload",
+                content,
+                46,
+                UserID.from_string("@user_id:whatever.org"),
+            )
+        )
+        # test with a text file
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/v1/media/download/test/{content_uri.media_id}",
+            shorthand=False,
+            access_token=self.tok,
+        )
+        self.pump()
+        self.assertEqual(200, channel.code)
+
+
+test_images = [
+    small_png,
+    small_png_with_transparency,
+    small_lossless_webp,
+    empty_file,
+    SVG,
+]
+input_values = [(x,) for x in test_images]
+
+
+@parameterized_class(("test_image",), input_values)
+class DownloadTestCase(unittest.HomeserverTestCase):
+    test_image: ClassVar[TestImage]
+    servlets = [
+        media.register_servlets,
+        login.register_servlets,
+        admin.register_servlets,
+    ]
+
+    def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
+        self.fetches: List[
+            Tuple[
+                "Deferred[Any]",
+                str,
+                str,
+                Optional[QueryParams],
+            ]
+        ] = []
+
+        def federation_get_file(
+            destination: str,
+            path: str,
+            output_stream: BinaryIO,
+            download_ratelimiter: Ratelimiter,
+            ip_address: Any,
+            max_size: int,
+            args: Optional[QueryParams] = None,
+            retry_on_dns_fail: bool = True,
+            ignore_backoff: bool = False,
+            follow_redirects: bool = False,
+        ) -> "Deferred[Tuple[int, Dict[bytes, List[bytes]], bytes]]":
+            """A mock for MatrixFederationHttpClient.federation_get_file."""
+
+            def write_to(
+                r: Tuple[bytes, Tuple[int, Dict[bytes, List[bytes]], bytes]]
+            ) -> Tuple[int, Dict[bytes, List[bytes]], bytes]:
+                data, response = r
+                output_stream.write(data)
+                return response
+
+            def write_err(f: Failure) -> Failure:
+                f.trap(HttpResponseException)
+                output_stream.write(f.value.response)
+                return f
+
+            d: Deferred[Tuple[bytes, Tuple[int, Dict[bytes, List[bytes]], bytes]]] = (
+                Deferred()
+            )
+            self.fetches.append((d, destination, path, args))
+            # Note that this callback changes the value held by d.
+            d_after_callback = d.addCallbacks(write_to, write_err)
+            return make_deferred_yieldable(d_after_callback)
+
+        def get_file(
+            destination: str,
+            path: str,
+            output_stream: BinaryIO,
+            download_ratelimiter: Ratelimiter,
+            ip_address: Any,
+            max_size: int,
+            args: Optional[QueryParams] = None,
+            retry_on_dns_fail: bool = True,
+            ignore_backoff: bool = False,
+            follow_redirects: bool = False,
+        ) -> "Deferred[Tuple[int, Dict[bytes, List[bytes]]]]":
+            """A mock for MatrixFederationHttpClient.get_file."""
+
+            def write_to(
+                r: Tuple[bytes, Tuple[int, Dict[bytes, List[bytes]]]]
+            ) -> Tuple[int, Dict[bytes, List[bytes]]]:
+                data, response = r
+                output_stream.write(data)
+                return response
+
+            def write_err(f: Failure) -> Failure:
+                f.trap(HttpResponseException)
+                output_stream.write(f.value.response)
+                return f
+
+            d: Deferred[Tuple[bytes, Tuple[int, Dict[bytes, List[bytes]]]]] = Deferred()
+            self.fetches.append((d, destination, path, args))
+            # Note that this callback changes the value held by d.
+            d_after_callback = d.addCallbacks(write_to, write_err)
+            return make_deferred_yieldable(d_after_callback)
+
+        # Mock out the homeserver's MatrixFederationHttpClient
+        client = Mock()
+        client.federation_get_file = federation_get_file
+        client.get_file = get_file
+
+        self.storage_path = self.mktemp()
+        self.media_store_path = self.mktemp()
+        os.mkdir(self.storage_path)
+        os.mkdir(self.media_store_path)
+
+        config = self.default_config()
+        config["media_store_path"] = self.media_store_path
+        config["max_image_pixels"] = 2000000
+
+        provider_config = {
+            "module": "synapse.media.storage_provider.FileStorageProviderBackend",
+            "store_local": True,
+            "store_synchronous": False,
+            "store_remote": True,
+            "config": {"directory": self.storage_path},
+        }
+        config["media_storage_providers"] = [provider_config]
+        config["experimental_features"] = {"msc3916_authenticated_media_enabled": True}
+
+        hs = self.setup_test_homeserver(config=config, federation_http_client=client)
+
+        return hs
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.store = hs.get_datastores().main
+        self.media_repo = hs.get_media_repository()
+
+        self.remote = "example.com"
+        self.media_id = "12345"
+
+        self.user = self.register_user("user", "pass")
+        self.tok = self.login("user", "pass")
+
+    def _req(
+        self, content_disposition: Optional[bytes], include_content_type: bool = True
+    ) -> FakeChannel:
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/v1/media/download/{self.remote}/{self.media_id}",
+            shorthand=False,
+            await_result=False,
+            access_token=self.tok,
+        )
+        self.pump()
+
+        # We've made one fetch, to example.com, using the federation media URL
+        self.assertEqual(len(self.fetches), 1)
+        self.assertEqual(self.fetches[0][1], "example.com")
+        self.assertEqual(
+            self.fetches[0][2], "/_matrix/federation/v1/media/download/" + self.media_id
+        )
+        self.assertEqual(
+            self.fetches[0][3],
+            {"timeout_ms": "20000"},
+        )
+
+        headers = {
+            b"Content-Length": [b"%d" % (len(self.test_image.data))],
+        }
+
+        if include_content_type:
+            headers[b"Content-Type"] = [self.test_image.content_type]
+
+        if content_disposition:
+            headers[b"Content-Disposition"] = [content_disposition]
+
+        self.fetches[0][0].callback(
+            (self.test_image.data, (len(self.test_image.data), headers, b"{}"))
+        )
+
+        self.pump()
+        self.assertEqual(channel.code, 200)
+
+        return channel
+
+    def test_handle_missing_content_type(self) -> None:
+        channel = self._req(
+            b"attachment; filename=out" + self.test_image.extension,
+            include_content_type=False,
+        )
+        headers = channel.headers
+        self.assertEqual(channel.code, 200)
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [b"application/octet-stream"]
+        )
+
+    def test_disposition_filename_ascii(self) -> None:
+        """
+        If the filename is filename=<ascii> then Synapse will decode it as an
+        ASCII string, and use filename= in the response.
+        """
+        channel = self._req(b"attachment; filename=out" + self.test_image.extension)
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [self.test_image.content_type]
+        )
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Disposition"),
+            [
+                (b"inline" if self.test_image.is_inline else b"attachment")
+                + b"; filename=out"
+                + self.test_image.extension
+            ],
+        )
+
+    def test_disposition_filenamestar_utf8escaped(self) -> None:
+        """
+        If the filename is filename=*utf8''<utf8 escaped> then Synapse will
+        correctly decode it as the UTF-8 string, and use filename* in the
+        response.
+        """
+        filename = parse.quote("\u2603".encode()).encode("ascii")
+        channel = self._req(
+            b"attachment; filename*=utf-8''" + filename + self.test_image.extension
+        )
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [self.test_image.content_type]
+        )
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Disposition"),
+            [
+                (b"inline" if self.test_image.is_inline else b"attachment")
+                + b"; filename*=utf-8''"
+                + filename
+                + self.test_image.extension
+            ],
+        )
+
+    def test_disposition_none(self) -> None:
+        """
+        If there is no filename, Content-Disposition should only
+        be a disposition type.
+        """
+        channel = self._req(None)
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Type"), [self.test_image.content_type]
+        )
+        self.assertEqual(
+            headers.getRawHeaders(b"Content-Disposition"),
+            [b"inline" if self.test_image.is_inline else b"attachment"],
+        )
+
+    def test_x_robots_tag_header(self) -> None:
+        """
+        Tests that the `X-Robots-Tag` header is present, which informs web crawlers
+        to not index, archive, or follow links in media.
+        """
+        channel = self._req(b"attachment; filename=out" + self.test_image.extension)
+
+        headers = channel.headers
+        self.assertEqual(
+            headers.getRawHeaders(b"X-Robots-Tag"),
+            [b"noindex, nofollow, noarchive, noimageindex"],
+        )
+
+    def test_cross_origin_resource_policy_header(self) -> None:
+        """
+        Test that the Cross-Origin-Resource-Policy header is set to "cross-origin"
+        allowing web clients to embed media from the downloads API.
+        """
+        channel = self._req(b"attachment; filename=out" + self.test_image.extension)
+
+        headers = channel.headers
+
+        self.assertEqual(
+            headers.getRawHeaders(b"Cross-Origin-Resource-Policy"),
+            [b"cross-origin"],
+        )
+
+    def test_unknown_federation_endpoint(self) -> None:
+        """
+        Test that if the downloadd request to remote federation endpoint returns a 404
+        we fall back to the _matrix/media endpoint
+        """
+        channel = self.make_request(
+            "GET",
+            f"/_matrix/client/v1/media/download/{self.remote}/{self.media_id}",
+            shorthand=False,
+            await_result=False,
+            access_token=self.tok,
+        )
+        self.pump()
+
+        # We've made one fetch, to example.com, using the media URL, and asking
+        # the other server not to do a remote fetch
+        self.assertEqual(len(self.fetches), 1)
+        self.assertEqual(self.fetches[0][1], "example.com")
+        self.assertEqual(
+            self.fetches[0][2], f"/_matrix/federation/v1/media/download/{self.media_id}"
+        )
+
+        # The result which says the endpoint is unknown.
+        unknown_endpoint = b'{"errcode":"M_UNRECOGNIZED","error":"Unknown request"}'
+        self.fetches[0][0].errback(
+            HttpResponseException(404, "NOT FOUND", unknown_endpoint)
+        )
+
+        self.pump()
+
+        # There should now be another request to the _matrix/media/v3/download URL.
+        self.assertEqual(len(self.fetches), 2)
+        self.assertEqual(self.fetches[1][1], "example.com")
+        self.assertEqual(
+            self.fetches[1][2],
+            f"/_matrix/media/v3/download/example.com/{self.media_id}",
+        )
+
+        headers = {
+            b"Content-Length": [b"%d" % (len(self.test_image.data))],
+        }
+
+        self.fetches[1][0].callback(
+            (self.test_image.data, (len(self.test_image.data), headers))
+        )
+
+        self.pump()
+        self.assertEqual(channel.code, 200)
--- a/tests/rest/client/test_sync.py
+++ b/tests/rest/client/test_sync.py
--- a/tests/rest/client/utils.py
+++ b/tests/rest/client/utils.py
@@ -261,9 +261,9 @@ class RestHelper:
        targ: str,
        expect_code: int = HTTPStatus.OK,
        tok: Optional[str] = None,
-    ) -> None:
+    ) -> JsonDict:
        """A convenience helper: `change_membership` with `membership` preset to "ban"."""
-        self.change_membership(
+        return self.change_membership(
            room=room,
            src=src,
            targ=targ,
--- a/tests/storage/test_stream.py
+++ b/tests/storage/test_stream.py
@@ -21,20 +21,32 @@

 import logging
 from typing import List, Tuple
+from unittest.mock import AsyncMock, patch

 from immutabledict import immutabledict

 from twisted.test.proto_helpers import MemoryReactor

-from synapse.api.constants import Direction, EventTypes, RelationTypes
+from synapse.api.constants import Direction, EventTypes, Membership, RelationTypes
 from synapse.api.filtering import Filter
+from synapse.crypto.event_signing import add_hashes_and_signatures
+from synapse.events import FrozenEventV3
+from synapse.federation.federation_client import SendJoinResult
 from synapse.rest import admin
 from synapse.rest.client import login, room
 from synapse.server import HomeServer
-from synapse.types import JsonDict, PersistedEventPosition, RoomStreamToken
+from synapse.storage.databases.main.stream import CurrentStateDeltaMembership
+from synapse.types import (
+    JsonDict,
+    PersistedEventPosition,
+    RoomStreamToken,
+    UserID,
+    create_requester,
+)
 from synapse.util import Clock

-from tests.unittest import HomeserverTestCase
+from tests.test_utils.event_injection import create_event
+from tests.unittest import FederatingHomeserverTestCase, HomeserverTestCase

 logger = logging.getLogger(__name__)

@@ -543,3 +555,859 @@ class GetLastEventInRoomBeforeStreamOrderingTestCase(HomeserverTestCase):
                }
            ),
        )
+
+
+class GetCurrentStateDeltaMembershipChangesForUserTestCase(HomeserverTestCase):
+    """
+    Test `get_current_state_delta_membership_changes_for_user(...)`
+    """
+
+    servlets = [
+        admin.register_servlets,
+        room.register_servlets,
+        login.register_servlets,
+    ]
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.store = hs.get_datastores().main
+        self.event_sources = hs.get_event_sources()
+        self.state_handler = self.hs.get_state_handler()
+        persistence = hs.get_storage_controllers().persistence
+        assert persistence is not None
+        self.persistence = persistence
+
+    def test_returns_membership_events(self) -> None:
+        """
+        A basic test that a membership event in the token range is returned for the user.
+        """
+        user1_id = self.register_user("user1", "pass")
+        user1_tok = self.login(user1_id, "pass")
+        user2_id = self.register_user("user2", "pass")
+        user2_tok = self.login(user2_id, "pass")
+
+        before_room1_token = self.event_sources.get_current_token()
+
+        room_id1 = self.helper.create_room_as(user2_id, tok=user2_tok)
+        join_response = self.helper.join(room_id1, user1_id, tok=user1_tok)
+        join_pos = self.get_success(
+            self.store.get_position_for_event(join_response["event_id"])
+        )
+
+        after_room1_token = self.event_sources.get_current_token()
+
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_room1_token.room_key,
+                to_key=after_room1_token.room_key,
+            )
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=join_response["event_id"],
+                    event_pos=join_pos,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                )
+            ],
+        )
+
+    def test_server_left_room_after_us(self) -> None:
+        """
+        Test that when probing over part of the DAG where the server left the room *after
+        us*, we still see the join and leave changes.
+
+        This is to make sure we play nicely with this behavior: When the server leaves a
+        room, it will insert new rows with `event_id = null` into the
+        `current_state_delta_stream` table for all current state.
+        """
+        user1_id = self.register_user("user1", "pass")
+        user1_tok = self.login(user1_id, "pass")
+        user2_id = self.register_user("user2", "pass")
+        user2_tok = self.login(user2_id, "pass")
+
+        before_room1_token = self.event_sources.get_current_token()
+
+        room_id1 = self.helper.create_room_as(
+            user2_id,
+            tok=user2_tok,
+            extra_content={
+                "power_level_content_override": {
+                    "users": {
+                        user2_id: 100,
+                        # Allow user1 to send state in the room
+                        user1_id: 100,
+                    }
+                }
+            },
+        )
+        join_response1 = self.helper.join(room_id1, user1_id, tok=user1_tok)
+        join_pos1 = self.get_success(
+            self.store.get_position_for_event(join_response1["event_id"])
+        )
+        # Make sure that random other non-member state that happens to have a `state_key`
+        # matching the user ID doesn't mess with things.
+        self.helper.send_state(
+            room_id1,
+            event_type="foobarbazdummy",
+            state_key=user1_id,
+            body={"foo": "bar"},
+            tok=user1_tok,
+        )
+        # User1 should leave the room first
+        leave_response1 = self.helper.leave(room_id1, user1_id, tok=user1_tok)
+        leave_pos1 = self.get_success(
+            self.store.get_position_for_event(leave_response1["event_id"])
+        )
+
+        # User2 should also leave the room (everyone has left the room which means the
+        # server is no longer in the room).
+        self.helper.leave(room_id1, user2_id, tok=user2_tok)
+
+        after_room1_token = self.event_sources.get_current_token()
+
+        # Get the membership changes for the user.
+        #
+        # At this point, the `current_state_delta_stream` table should look like the
+        # following. When the server leaves a room, it will insert new rows with
+        # `event_id = null` for all current state.
+        #
+        # | stream_id | room_id  | type                        | state_key      | event_id | prev_event_id |
+        # |-----------|----------|-----------------------------|----------------|----------|---------------|
+        # | 2         | !x:test  | 'm.room.create'             | ''             | $xxx     | None          |
+        # | 3         | !x:test  | 'm.room.member'             | '@user2:test'  | $aaa     | None          |
+        # | 4         | !x:test  | 'm.room.history_visibility' | ''             | $xxx     | None          |
+        # | 4         | !x:test  | 'm.room.join_rules'         | ''             | $xxx     | None          |
+        # | 4         | !x:test  | 'm.room.power_levels'       | ''             | $xxx     | None          |
+        # | 7         | !x:test  | 'm.room.member'             | '@user1:test'  | $ooo     | None          |
+        # | 8         | !x:test  | 'foobarbazdummy'            | '@user1:test'  | $xxx     | None          |
+        # | 9         | !x:test  | 'm.room.member'             | '@user1:test'  | $ppp     | $ooo          |
+        # | 10        | !x:test  | 'foobarbazdummy'            | '@user1:test'  | None     | $xxx          |
+        # | 10        | !x:test  | 'm.room.create'             | ''             | None     | $xxx          |
+        # | 10        | !x:test  | 'm.room.history_visibility' | ''             | None     | $xxx          |
+        # | 10        | !x:test  | 'm.room.join_rules'         | ''             | None     | $xxx          |
+        # | 10        | !x:test  | 'm.room.member'             | '@user1:test'  | None     | $ppp          |
+        # | 10        | !x:test  | 'm.room.member'             | '@user2:test'  | None     | $aaa          |
+        # | 10        | !x:test  | 'm.room.power_levels'       |                | None     | $xxx          |
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_room1_token.room_key,
+                to_key=after_room1_token.room_key,
+            )
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=join_response1["event_id"],
+                    event_pos=join_pos1,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                ),
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=leave_response1["event_id"],
+                    event_pos=leave_pos1,
+                    membership="leave",
+                    sender=user1_id,
+                    prev_event_id=join_response1["event_id"],
+                    prev_event_pos=join_pos1,
+                    prev_membership="join",
+                    prev_sender=user1_id,
+                ),
+            ],
+        )
+
+    def test_server_left_room_after_us_later(self) -> None:
+        """
+        Test when the user leaves the room, then sometime later, everyone else leaves
+        the room, causing the server to leave the room, we shouldn't see any membership
+        changes.
+
+        This is to make sure we play nicely with this behavior: When the server leaves a
+        room, it will insert new rows with `event_id = null` into the
+        `current_state_delta_stream` table for all current state.
+        """
+        user1_id = self.register_user("user1", "pass")
+        user1_tok = self.login(user1_id, "pass")
+        user2_id = self.register_user("user2", "pass")
+        user2_tok = self.login(user2_id, "pass")
+
+        room_id1 = self.helper.create_room_as(user2_id, tok=user2_tok)
+        self.helper.join(room_id1, user1_id, tok=user1_tok)
+        # User1 should leave the room first
+        self.helper.leave(room_id1, user1_id, tok=user1_tok)
+
+        after_user1_leave_token = self.event_sources.get_current_token()
+
+        # User2 should also leave the room (everyone has left the room which means the
+        # server is no longer in the room).
+        self.helper.leave(room_id1, user2_id, tok=user2_tok)
+
+        after_server_leave_token = self.event_sources.get_current_token()
+
+        # Join another room as user1 just to advance the stream_ordering and bust
+        # `_membership_stream_cache`
+        room_id2 = self.helper.create_room_as(user2_id, tok=user2_tok)
+        self.helper.join(room_id2, user1_id, tok=user1_tok)
+
+        # Get the membership changes for the user.
+        #
+        # At this point, the `current_state_delta_stream` table should look like the
+        # following. When the server leaves a room, it will insert new rows with
+        # `event_id = null` for all current state.
+        #
+        # TODO: Add DB rows to better see what's going on.
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=after_user1_leave_token.room_key,
+                to_key=after_server_leave_token.room_key,
+            )
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [],
+        )
+
+    def test_we_cause_server_left_room(self) -> None:
+        """
+        Test that when probing over part of the DAG where the user leaves the room
+        causing the server to leave the room (because we were the last local user in the
+        room), we still see the join and leave changes.
+
+        This is to make sure we play nicely with this behavior: When the server leaves a
+        room, it will insert new rows with `event_id = null` into the
+        `current_state_delta_stream` table for all current state.
+        """
+        user1_id = self.register_user("user1", "pass")
+        user1_tok = self.login(user1_id, "pass")
+        user2_id = self.register_user("user2", "pass")
+        user2_tok = self.login(user2_id, "pass")
+
+        before_room1_token = self.event_sources.get_current_token()
+
+        room_id1 = self.helper.create_room_as(
+            user2_id,
+            tok=user2_tok,
+            extra_content={
+                "power_level_content_override": {
+                    "users": {
+                        user2_id: 100,
+                        # Allow user1 to send state in the room
+                        user1_id: 100,
+                    }
+                }
+            },
+        )
+        join_response1 = self.helper.join(room_id1, user1_id, tok=user1_tok)
+        join_pos1 = self.get_success(
+            self.store.get_position_for_event(join_response1["event_id"])
+        )
+        # Make sure that random other non-member state that happens to have a `state_key`
+        # matching the user ID doesn't mess with things.
+        self.helper.send_state(
+            room_id1,
+            event_type="foobarbazdummy",
+            state_key=user1_id,
+            body={"foo": "bar"},
+            tok=user1_tok,
+        )
+
+        # User2 should leave the room first.
+        self.helper.leave(room_id1, user2_id, tok=user2_tok)
+
+        # User1 (the person we're testing with) should also leave the room (everyone has
+        # left the room which means the server is no longer in the room).
+        leave_response1 = self.helper.leave(room_id1, user1_id, tok=user1_tok)
+        leave_pos1 = self.get_success(
+            self.store.get_position_for_event(leave_response1["event_id"])
+        )
+
+        after_room1_token = self.event_sources.get_current_token()
+
+        # Get the membership changes for the user.
+        #
+        # At this point, the `current_state_delta_stream` table should look like the
+        # following. When the server leaves a room, it will insert new rows with
+        # `event_id = null` for all current state.
+        #
+        # | stream_id | room_id   | type                        | state_key     | event_id | prev_event_id |
+        # |-----------|-----------|-----------------------------|---------------|----------|---------------|
+        # | 2         | '!x:test' | 'm.room.create'             | ''            | '$xxx'   | None          |
+        # | 3         | '!x:test' | 'm.room.member'             | '@user2:test' | '$aaa'   | None          |
+        # | 4         | '!x:test' | 'm.room.history_visibility' | ''            | '$xxx'   | None          |
+        # | 4         | '!x:test' | 'm.room.join_rules'         | ''            | '$xxx'   | None          |
+        # | 4         | '!x:test' | 'm.room.power_levels'       | ''            | '$xxx'   | None          |
+        # | 7         | '!x:test' | 'm.room.member'             | '@user1:test' | '$ooo'   | None          |
+        # | 8         | '!x:test' | 'foobarbazdummy'            | '@user1:test' | '$xxx'   | None          |
+        # | 9         | '!x:test' | 'm.room.member'             | '@user2:test' | '$bbb'   | '$aaa'        |
+        # | 10        | '!x:test' | 'foobarbazdummy'            | '@user1:test' | None     | '$xxx'        |
+        # | 10        | '!x:test' | 'm.room.create'             | ''            | None     | '$xxx'        |
+        # | 10        | '!x:test' | 'm.room.history_visibility' | ''            | None     | '$xxx'        |
+        # | 10        | '!x:test' | 'm.room.join_rules'         | ''            | None     | '$xxx'        |
+        # | 10        | '!x:test' | 'm.room.member'             | '@user1:test' | None     | '$ooo'        |
+        # | 10        | '!x:test' | 'm.room.member'             | '@user2:test' | None     | '$bbb'        |
+        # | 10        | '!x:test' | 'm.room.power_levels'       | ''            | None     | '$xxx'        |
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_room1_token.room_key,
+                to_key=after_room1_token.room_key,
+            )
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=join_response1["event_id"],
+                    event_pos=join_pos1,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                ),
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=None,  # leave_response1["event_id"],
+                    event_pos=leave_pos1,
+                    membership="leave",
+                    sender=None,  # user1_id,
+                    prev_event_id=join_response1["event_id"],
+                    prev_event_pos=join_pos1,
+                    prev_membership="join",
+                    prev_sender=user1_id,
+                ),
+            ],
+        )
+
+    def test_different_user_membership_persisted_in_same_batch(self) -> None:
+        """
+        Test batch of membership events from different users being processed at once.
+        This will result in all of the memberships being stored in the
+        `current_state_delta_stream` table with the same `stream_ordering` even though
+        the individual events have different `stream_ordering`s.
+        """
+        user1_id = self.register_user("user1", "pass")
+        _user1_tok = self.login(user1_id, "pass")
+        user2_id = self.register_user("user2", "pass")
+        user2_tok = self.login(user2_id, "pass")
+        user3_id = self.register_user("user3", "pass")
+        _user3_tok = self.login(user3_id, "pass")
+        user4_id = self.register_user("user4", "pass")
+        _user4_tok = self.login(user4_id, "pass")
+
+        before_room1_token = self.event_sources.get_current_token()
+
+        # User2 is just the designated person to create the room (we do this across the
+        # tests to be consistent)
+        room_id1 = self.helper.create_room_as(user2_id, tok=user2_tok)
+
+        # Persist the user1, user3, and user4 join events in the same batch so they all
+        # end up in the `current_state_delta_stream` table with the same
+        # stream_ordering.
+        join_event3, join_event_context3 = self.get_success(
+            create_event(
+                self.hs,
+                sender=user3_id,
+                type=EventTypes.Member,
+                state_key=user3_id,
+                content={"membership": "join"},
+                room_id=room_id1,
+            )
+        )
+        # We want to put user1 in the middle of the batch. This way, regardless of the
+        # implementation that inserts rows into current_state_delta_stream` (whether it
+        # be minimum/maximum of stream position of the batch), we will still catch bugs.
+        join_event1, join_event_context1 = self.get_success(
+            create_event(
+                self.hs,
+                sender=user1_id,
+                type=EventTypes.Member,
+                state_key=user1_id,
+                content={"membership": "join"},
+                room_id=room_id1,
+            )
+        )
+        join_event4, join_event_context4 = self.get_success(
+            create_event(
+                self.hs,
+                sender=user4_id,
+                type=EventTypes.Member,
+                state_key=user4_id,
+                content={"membership": "join"},
+                room_id=room_id1,
+            )
+        )
+        self.get_success(
+            self.persistence.persist_events(
+                [
+                    (join_event3, join_event_context3),
+                    (join_event1, join_event_context1),
+                    (join_event4, join_event_context4),
+                ]
+            )
+        )
+
+        after_room1_token = self.event_sources.get_current_token()
+
+        # Get the membership changes for the user.
+        #
+        # At this point, the `current_state_delta_stream` table should look like (notice
+        # those three memberships at the end with `stream_id=7` because we persisted
+        # them in the same batch):
+        #
+        # | stream_id | room_id   | type                       | state_key        | event_id | prev_event_id |
+        # |-----------|-----------|----------------------------|------------------|----------|---------------|
+        # | 2         | '!x:test' | 'm.room.create'            | ''               | '$xxx'   | None          |
+        # | 3         | '!x:test' | 'm.room.member'            | '@user2:test'    | '$xxx'   | None          |
+        # | 4         | '!x:test' | 'm.room.history_visibility'| ''               | '$xxx'   | None          |
+        # | 4         | '!x:test' | 'm.room.join_rules'        | ''               | '$xxx'   | None          |
+        # | 4         | '!x:test' | 'm.room.power_levels'      | ''               | '$xxx'   | None          |
+        # | 7         | '!x:test' | 'm.room.member'            | '@user3:test'    | '$xxx'   | None          |
+        # | 7         | '!x:test' | 'm.room.member'            | '@user1:test'    | '$xxx'   | None          |
+        # | 7         | '!x:test' | 'm.room.member'            | '@user4:test'    | '$xxx'   | None          |
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_room1_token.room_key,
+                to_key=after_room1_token.room_key,
+            )
+        )
+
+        join_pos3 = self.get_success(
+            self.store.get_position_for_event(join_event3.event_id)
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=join_event1.event_id,
+                    # Ideally, this would be `join_pos1` (to match the `event_id`) but
+                    # when events are persisted in a batch, they are all stored in the
+                    # `current_state_delta_stream` table with the minimum
+                    # `stream_ordering` from the batch.
+                    event_pos=join_pos3,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                ),
+            ],
+        )
+
+    def test_state_reset(self) -> None:
+        """
+        Test a state reset scenario where the user gets removed from the room (when
+        there is no corresponding leave event)
+        """
+        user1_id = self.register_user("user1", "pass")
+        user1_tok = self.login(user1_id, "pass")
+        user2_id = self.register_user("user2", "pass")
+        user2_tok = self.login(user2_id, "pass")
+
+        room_id1 = self.helper.create_room_as(user2_id, tok=user2_tok)
+        join_response1 = self.helper.join(room_id1, user1_id, tok=user1_tok)
+        join_pos1 = self.get_success(
+            self.store.get_position_for_event(join_response1["event_id"])
+        )
+
+        before_reset_token = self.event_sources.get_current_token()
+
+        # Send another state event to make a position for the state reset to happen at
+        dummy_state_response = self.helper.send_state(
+            room_id1,
+            event_type="foobarbaz",
+            state_key="",
+            body={"foo": "bar"},
+            tok=user2_tok,
+        )
+        dummy_state_pos = self.get_success(
+            self.store.get_position_for_event(dummy_state_response["event_id"])
+        )
+
+        # Mock a state reset removing the membership for user1 in the current state
+        self.get_success(
+            self.store.db_pool.simple_delete(
+                table="current_state_events",
+                keyvalues={
+                    "room_id": room_id1,
+                    "type": EventTypes.Member,
+                    "state_key": user1_id,
+                },
+                desc="state reset user in current_state_delta_stream",
+            )
+        )
+        self.get_success(
+            self.store.db_pool.simple_insert(
+                table="current_state_delta_stream",
+                values={
+                    "stream_id": dummy_state_pos.stream,
+                    "room_id": room_id1,
+                    "type": EventTypes.Member,
+                    "state_key": user1_id,
+                    "event_id": None,
+                    "prev_event_id": join_response1["event_id"],
+                    "instance_name": dummy_state_pos.instance_name,
+                },
+                desc="state reset user in current_state_delta_stream",
+            )
+        )
+
+        # Manually bust the cache since we we're just manually messing with the database
+        # and not causing an actual state reset.
+        self.store._membership_stream_cache.entity_has_changed(
+            user1_id, dummy_state_pos.stream
+        )
+
+        after_reset_token = self.event_sources.get_current_token()
+
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_reset_token.room_key,
+                to_key=after_reset_token.room_key,
+            )
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=None,
+                    event_pos=dummy_state_pos,
+                    membership="leave",
+                    sender=None,  # user1_id,
+                    prev_event_id=join_response1["event_id"],
+                    prev_event_pos=join_pos1,
+                    prev_membership="join",
+                    prev_sender=user1_id,
+                ),
+            ],
+        )
+
+    def test_excluded_room_ids(self) -> None:
+        """
+        Test that the `excluded_room_ids` option excludes changes from the specified rooms.
+        """
+        user1_id = self.register_user("user1", "pass")
+        user1_tok = self.login(user1_id, "pass")
+        user2_id = self.register_user("user2", "pass")
+        user2_tok = self.login(user2_id, "pass")
+
+        before_room1_token = self.event_sources.get_current_token()
+
+        room_id1 = self.helper.create_room_as(user2_id, tok=user2_tok)
+        join_response1 = self.helper.join(room_id1, user1_id, tok=user1_tok)
+        join_pos1 = self.get_success(
+            self.store.get_position_for_event(join_response1["event_id"])
+        )
+
+        room_id2 = self.helper.create_room_as(user2_id, tok=user2_tok)
+        join_response2 = self.helper.join(room_id2, user1_id, tok=user1_tok)
+        join_pos2 = self.get_success(
+            self.store.get_position_for_event(join_response2["event_id"])
+        )
+
+        after_room1_token = self.event_sources.get_current_token()
+
+        # First test the the room is returned without the `excluded_room_ids` option
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_room1_token.room_key,
+                to_key=after_room1_token.room_key,
+            )
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=join_response1["event_id"],
+                    event_pos=join_pos1,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                ),
+                CurrentStateDeltaMembership(
+                    room_id=room_id2,
+                    event_id=join_response2["event_id"],
+                    event_pos=join_pos2,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                ),
+            ],
+        )
+
+        # The test that `excluded_room_ids` excludes room2 as expected
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_room1_token.room_key,
+                to_key=after_room1_token.room_key,
+                excluded_room_ids=[room_id2],
+            )
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=room_id1,
+                    event_id=join_response1["event_id"],
+                    event_pos=join_pos1,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                )
+            ],
+        )
+
+
+class GetCurrentStateDeltaMembershipChangesForUserFederationTestCase(
+    FederatingHomeserverTestCase
+):
+    """
+    Test `get_current_state_delta_membership_changes_for_user(...)` when joining remote federated rooms.
+    """
+
+    servlets = [
+        admin.register_servlets_for_client_rest_resource,
+        room.register_servlets,
+        login.register_servlets,
+    ]
+
+    def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
+        self.sliding_sync_handler = self.hs.get_sliding_sync_handler()
+        self.store = self.hs.get_datastores().main
+        self.event_sources = hs.get_event_sources()
+        self.room_member_handler = hs.get_room_member_handler()
+
+    def test_remote_join(self) -> None:
+        """
+        Test remote join where the first rows in `current_state_delta_stream` will just
+        be the state when you joined the remote room.
+        """
+        user1_id = self.register_user("user1", "pass")
+        _user1_tok = self.login(user1_id, "pass")
+
+        before_join_token = self.event_sources.get_current_token()
+
+        intially_unjoined_room_id = f"!example:{self.OTHER_SERVER_NAME}"
+
+        # Remotely join a room on another homeserver.
+        #
+        # To do this we have to mock the responses from the remote homeserver. We also
+        # patch out a bunch of event checks on our end.
+        create_event_source = {
+            "auth_events": [],
+            "content": {
+                "creator": f"@creator:{self.OTHER_SERVER_NAME}",
+                "room_version": self.hs.config.server.default_room_version.identifier,
+            },
+            "depth": 0,
+            "origin_server_ts": 0,
+            "prev_events": [],
+            "room_id": intially_unjoined_room_id,
+            "sender": f"@creator:{self.OTHER_SERVER_NAME}",
+            "state_key": "",
+            "type": EventTypes.Create,
+        }
+        self.add_hashes_and_signatures_from_other_server(
+            create_event_source,
+            self.hs.config.server.default_room_version,
+        )
+        create_event = FrozenEventV3(
+            create_event_source,
+            self.hs.config.server.default_room_version,
+            {},
+            None,
+        )
+        creator_join_event_source = {
+            "auth_events": [create_event.event_id],
+            "content": {
+                "membership": "join",
+            },
+            "depth": 1,
+            "origin_server_ts": 1,
+            "prev_events": [],
+            "room_id": intially_unjoined_room_id,
+            "sender": f"@creator:{self.OTHER_SERVER_NAME}",
+            "state_key": f"@creator:{self.OTHER_SERVER_NAME}",
+            "type": EventTypes.Member,
+        }
+        self.add_hashes_and_signatures_from_other_server(
+            creator_join_event_source,
+            self.hs.config.server.default_room_version,
+        )
+        creator_join_event = FrozenEventV3(
+            creator_join_event_source,
+            self.hs.config.server.default_room_version,
+            {},
+            None,
+        )
+
+        # Our local user is going to remote join the room
+        join_event_source = {
+            "auth_events": [create_event.event_id],
+            "content": {"membership": "join"},
+            "depth": 1,
+            "origin_server_ts": 100,
+            "prev_events": [creator_join_event.event_id],
+            "sender": user1_id,
+            "state_key": user1_id,
+            "room_id": intially_unjoined_room_id,
+            "type": EventTypes.Member,
+        }
+        add_hashes_and_signatures(
+            self.hs.config.server.default_room_version,
+            join_event_source,
+            self.hs.hostname,
+            self.hs.signing_key,
+        )
+        join_event = FrozenEventV3(
+            join_event_source,
+            self.hs.config.server.default_room_version,
+            {},
+            None,
+        )
+
+        mock_make_membership_event = AsyncMock(
+            return_value=(
+                self.OTHER_SERVER_NAME,
+                join_event,
+                self.hs.config.server.default_room_version,
+            )
+        )
+        mock_send_join = AsyncMock(
+            return_value=SendJoinResult(
+                join_event,
+                self.OTHER_SERVER_NAME,
+                state=[create_event, creator_join_event],
+                auth_chain=[create_event, creator_join_event],
+                partial_state=False,
+                servers_in_room=frozenset(),
+            )
+        )
+
+        with patch.object(
+            self.room_member_handler.federation_handler.federation_client,
+            "make_membership_event",
+            mock_make_membership_event,
+        ), patch.object(
+            self.room_member_handler.federation_handler.federation_client,
+            "send_join",
+            mock_send_join,
+        ), patch(
+            "synapse.event_auth._is_membership_change_allowed",
+            return_value=None,
+        ), patch(
+            "synapse.handlers.federation_event.check_state_dependent_auth_rules",
+            return_value=None,
+        ):
+            self.get_success(
+                self.room_member_handler.update_membership(
+                    requester=create_requester(user1_id),
+                    target=UserID.from_string(user1_id),
+                    room_id=intially_unjoined_room_id,
+                    action=Membership.JOIN,
+                    remote_room_hosts=[self.OTHER_SERVER_NAME],
+                )
+            )
+
+        after_join_token = self.event_sources.get_current_token()
+
+        # Get the membership changes for the user.
+        #
+        # At this point, the `current_state_delta_stream` table should look like the
+        # following. Notice that all of the events are at the same `stream_id` because
+        # the current state starts out where we remotely joined:
+        #
+        # | stream_id | room_id                      | type            | state_key                    | event_id | prev_event_id |
+        # |-----------|------------------------------|-----------------|------------------------------|----------|---------------|
+        # | 2         | '!example:other.example.com' | 'm.room.member' | '@user1:test'                | '$xxx'   | None          |
+        # | 2         | '!example:other.example.com' | 'm.room.create' | ''                           | '$xxx'   | None          |
+        # | 2         | '!example:other.example.com' | 'm.room.member' | '@creator:other.example.com' | '$xxx'   | None          |
+        membership_changes = self.get_success(
+            self.store.get_current_state_delta_membership_changes_for_user(
+                user1_id,
+                from_key=before_join_token.room_key,
+                to_key=after_join_token.room_key,
+            )
+        )
+
+        join_pos = self.get_success(
+            self.store.get_position_for_event(join_event.event_id)
+        )
+
+        # Let the whole diff show on failure
+        self.maxDiff = None
+        self.assertEqual(
+            membership_changes,
+            [
+                CurrentStateDeltaMembership(
+                    room_id=intially_unjoined_room_id,
+                    event_id=join_event.event_id,
+                    event_pos=join_pos,
+                    membership="join",
+                    sender=user1_id,
+                    prev_event_id=None,
+                    prev_event_pos=None,
+                    prev_membership=None,
+                    prev_sender=None,
+                ),
+            ],
+        )
Author	SHA1	Message	Date
Devon Hudson	0471547e96	Add changelog entry	2024-07-03 18:07:14 -06:00
Devon Hudson	e891986eb0	Track complement release branch when releasing	2024-07-03 18:03:40 -06:00
Devon Hudson	0c4f7a3d16	Merge branch 'master' into develop	2024-07-03 10:19:23 -06:00
Eric Eastwood	7be03d854b	Add `room_types`/`not_room_types` filtering to Sliding Sync `/sync` (#17337 ) Based on [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575): Sliding Sync	2024-07-02 12:46:27 -05:00
Eric Eastwood	fa91655805	Return some room data in Sliding Sync `/sync` (#17320 ) - Timeline events - Stripped `invite_state` Based on [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575): Sliding Sync	2024-07-02 11:07:05 -05:00
Devon Hudson	0d2b75cf92	Merge branch 'release-v1.110' into develop	2024-07-02 09:53:32 -06:00
Erik Johnston	99c107920d	Merge remote-tracking branch 'origin/release-v1.110' into develop	2024-07-02 15:12:36 +01:00
Shay	8f890447b0	Support MSC3916 by adding `_matrix/client/v1/media/download` endpoint (#17365 )	2024-07-02 14:07:04 +01:00
Erik Johnston	b3b793786c	Fix sync waiting for an invalid token from the "future" (#17386 ) Fixes https://github.com/element-hq/synapse/issues/17274, hopefully. Basically, old versions of Synapse could advance streams without persisting anything in the DB (fixed in #17229). On restart those updates would get lost, and so the position of the stream would revert to an older position. If this happened across an upgrade to a later Synapse version which included #17215, then sync could get blocked indefinitely (until the stream advanced to the position in the token). We fix this by bounding the stream positions we'll wait for to the maximum position of the underlying stream ID generator.	2024-07-02 12:39:49 +01:00
Erik Johnston	9c8f1a6d41	Fix building debian packages on non-clean checkouts (#17390 ) If we leave the `.so` in place it causes the tests to fail, as it gets picked up (instead of the newly built .so) and so fails with mismatched GLIBC errors.	2024-07-02 12:39:32 +01:00
dependabot[bot]	635e3927d2	Bump types-setuptools from 69.5.0.20240423 to 70.1.0.20240627 (#17380 )	2024-07-01 17:46:58 +01:00
dependabot[bot]	a1b8897668	Bump serde_json from 1.0.117 to 1.0.119 (#17385 )	2024-07-01 13:42:37 +01:00
dependabot[bot]	76b9f14c0a	Bump log from 0.4.21 to 0.4.22 (#17384 )	2024-07-01 13:42:00 +01:00
dependabot[bot]	1eccbfb82f	Bump cryptography from 42.0.7 to 42.0.8 (#17382 )	2024-07-01 13:41:48 +01:00
Erik Johnston	2f5a77efae	Limit size of presence EDUs (#17371 ) Otherwise they are unbounded. --------- Co-authored-by: Andrew Morgan <1342360+anoadragon453@users.noreply.github.com>	2024-07-01 12:48:36 +01:00
davidegirardi	b11f5c984b	Clarify `url_preview_url_blacklist` is a usability feature (#17356 )	2024-06-28 14:39:54 +01:00
Till	27756c9fdf	Use rstcheck to "lint" the README (#17367 ) Follow up to https://github.com/element-hq/synapse/pull/17363, so we can detect issues with the RST file early on. ### Pull Request Checklist <!-- Please read https://element-hq.github.io/synapse/latest/development/contributing_guide.html before submitting your pull request --> * [x] Pull request is based on the develop branch * [x] Pull request includes a [changelog file](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#changelog). The entry should: - Be a short description of your change which makes sense to users. "Fixed a bug that prevented receiving messages from other servers." instead of "Moved X method from `EventStore` to `EventWorkerStore`.". - Use markdown where necessary, mostly for `code blocks`. - End with either a period (.) or an exclamation mark (!). - Start with a capital letter. - Feel free to credit yourself, by adding a sentence "Contributed by @github_username." or "Contributed by [Your Name]." to the end of the entry. * [x] [Code style](https://element-hq.github.io/synapse/latest/code_style.html) is correct (run the [linters](https://element-hq.github.io/synapse/latest/development/contributing_guide.html#run-the-linters))	2024-06-27 13:36:08 +02:00
Erik Johnston	cc5e5893fe	Handle multiple rows device inbox (#17362 ) Fix bug where we don't get new to-device from remote if they resent a message we've already persisted and have recorded in the DB twice. `device_federation_inbox` table doesn't have a unique index, and so we can race and store an entry in there twice. If we do so then `simple_select_one_txn` will throw an error due to the query returning more than one row. We should add an unique index, but it doesn't really matter so lets just handle the case of multiple rows correctly for now.	2024-06-27 11:04:31 +01:00
Till Faelligen	7c169f4d2c	Merge branch 'release-v1.110' into develop	2024-06-26 19:00:51 +02:00
Till	b924a8e1a9	Fix uploading packages to PyPi (#17363 ) As per https://github.com/sphinx-doc/sphinx/issues/3921#issuecomment-315581557, we need double underscores. Running `rst2html README.rst > /dev/null` found some more warnings.	2024-06-26 18:01:39 +02:00
				`@@ -0,0 +1 @@`
				Add `rooms` data to experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync` endpoint.
				`@@ -0,0 +1 @@`
				Add `room_types`/`not_room_types` filtering to experimental [MSC3575](https://github.com/matrix-org/matrix-spec-proposals/pull/3575) Sliding Sync `/sync` endpoint.
				`@@ -0,0 +1 @@`
				Clarify `url_preview_url_blacklist` is a usability feature.
				`@@ -0,0 +1 @@`
				`Fix rare race which causes no new to-device messages to be received from remote server.`
				`@@ -0,0 +1 @@`
				`Support [MSC3916](https://github.com/matrix-org/matrix-spec-proposals/blob/rav/authentication-for-media/proposals/3916-authentication-for-media.md) by adding _matrix/client/v1/media/download endpoint.`
				`@@ -0,0 +1 @@`
				`Fix building debian packages on non-clean checkouts.`
				`@@ -0,0 +1 @@`
				`Pin CI to complement release branch for releases.`