Support for experimental MSC4335 error code for media upload limits

changelog.d/18876.feature

@@ -0,0 +1 @@
+Add support for experimental [MSC4335](https://github.com/matrix-org/matrix-spec-proposals/pull/4335) M_USER_LIMIT_EXCEEDED error code for media upload limits.

docs/usage/configuration/config_documentation.md

@@ -2174,13 +2174,28 @@ These settings can be overridden using the `get_media_upload_limits_for_user` mo
 
 Defaults to `[]`.
 
+Options for each entry include:
+
+* `time_period` (duration): The time period over which the limit applies. Required.
+
+* `max_size` (byte size): Amount of data that can be uploaded in the time period by the user. Required.
+
+* `msc4335_info_uri` (string): Experimental MSC4335 URI to where the user can find information about the upload limit. Optional.
+
+* `msc4335_soft_limit` (boolean): Experimental MSC4335 value to say if the limit can be increased. Optional.
+
+* `msc4335_increase_uri` (string): Experimental MSC4335 URI to where the user can increase the upload limit. Required if msc4335_soft_limit is true.
+
 Example configuration:
 ```yaml
 media_upload_limits:
 - time_period: 1h
   max_size: 100M
 - time_period: 1w
   max_size: 500M
+  msc4335_info_uri: https://example.com/quota
+  msc4335_soft_limit: true
+  msc4335_increase_uri: https://example.com/increase-quota
 ```
 ---
 ### `max_image_pixels`

schema/synapse-config.schema.yaml

@@ -2424,20 +2424,40 @@ properties:
       module API [callback](../../modules/media_repository_callbacks.md#get_media_upload_limits_for_user).
     default: []
     items:
-      time_period:
-        type: "#/$defs/duration"
-        description: >-
-          The time period over which the limit applies. Required.
-      max_size:
-        type: "#/$defs/bytes"
-        description: >-
-          Amount of data that can be uploaded in the time period by the user.
-          Required.
+      type: object
+      required:
+        - time_period
+        - max_size
+      properties:
+        time_period:
+          $ref: "#/$defs/duration"
+          description: >-
+            The time period over which the limit applies. Required.
+        max_size:
+          $ref: "#/$defs/bytes"
+          description: >-
+            Amount of data that can be uploaded in the time period by the user.
+            Required.
+        msc4335_info_uri:
+          type: string
+          description: >-
+            Experimental MSC4335 URI to where the user can find information about the upload limit. Optional.
+        msc4335_soft_limit:
+          type: boolean
+          description: >-
+            Experimental MSC4335 value to say if the limit can be increased. Optional.
+        msc4335_increase_uri:
+          type: string
+          description: >-
+            Experimental MSC4335 URI to where the user can increase the upload limit. Required if msc4335_soft_limit is true.
     examples:
       - - time_period: 1h
           max_size: 100M
         - time_period: 1w
           max_size: 500M
+          msc4335_info_uri: https://example.com/quota
+          msc4335_soft_limit: true
+          msc4335_increase_uri: https://example.com/increase-quota
   max_image_pixels:
     $ref: "#/$defs/bytes"
     description: Maximum number of pixels that will be thumbnailed.

synapse/api/errors.py

@@ -152,6 +152,8 @@ class Codes(str, Enum):
     # Part of MSC4326
     UNKNOWN_DEVICE = "ORG.MATRIX.MSC4326.M_UNKNOWN_DEVICE"
 
+    MSC4335_USER_LIMIT_EXCEEDED = "ORG.MATRIX.MSC4335_USER_LIMIT_EXCEEDED"
+
 
 class CodeMessageException(RuntimeError):
     """An exception with integer code, a message string attributes and optional headers.
@@ -513,6 +515,37 @@ def error_dict(self, config: Optional["HomeServerConfig"]) -> "JsonDict":
         )
 
 
+class MSC4335UserLimitExceededError(SynapseError):
+    """
+    Experimental implementation of MSC4335 M_USER_LIMIT_EXCEEDED error
+    """
+
+    def __init__(
+        self,
+        code: int,
+        msg: str,
+        info_uri: str,
+        soft_limit: bool,
+        increase_uri: Optional[str] = None,
+    ):
+        if soft_limit and increase_uri is None:
+            raise ValueError("increase_uri must be provided if soft_limit is True")
+
+        additional_fields: dict[str, Union[str, bool]] = {
+            "org.matrix.msc4335.info_uri": info_uri,
+            "org.matrix.msc4335.soft_limit": soft_limit,
+        }
+        if soft_limit and increase_uri is not None:
+            additional_fields["org.matrix.msc4335.increase_uri"] = increase_uri
+
+        super().__init__(
+            code,
+            msg,
+            Codes.MSC4335_USER_LIMIT_EXCEEDED,
+            additional_fields=additional_fields,
+        )
+
+
 class EventSizeError(SynapseError):
     """An error raised when an event is too big."""
 

synapse/config/experimental.py

@@ -598,3 +598,6 @@ def read_config(
         # MSC4306: Thread Subscriptions
         # (and MSC4308: Thread Subscriptions extension to Sliding Sync)
         self.msc4306_enabled: bool = experimental.get("msc4306_enabled", False)
+
+        # MSC4335: M_USER_LIMIT_EXCEEDED error
+        self.msc4335_enabled: bool = experimental.get("msc4335_enabled", False)

synapse/config/repository.py

@@ -21,7 +21,7 @@
 
 import logging
 import os
-from typing import Any, Dict, List, Tuple
+from typing import Any, Dict, List, Optional, Tuple
 
 import attr
 
@@ -134,6 +134,15 @@ class MediaUploadLimit:
     time_period_ms: int
     """The time period in milliseconds."""
 
+    msc4335_info_uri: Optional[str] = None
+    """Used for experimental MSC4335 error code feature"""
+
+    msc4335_soft_limit: Optional[bool] = None
+    """Used for experimental MSC4335 error code feature"""
+
+    msc4335_increase_uri: Optional[str] = None
+    """Used for experimental MSC4335 error code feature"""
+
 
 class ContentRepositoryConfig(Config):
     section = "media"
@@ -302,8 +311,34 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
         for limit_config in config.get("media_upload_limits", []):
             time_period_ms = self.parse_duration(limit_config["time_period"])
             max_bytes = self.parse_size(limit_config["max_size"])
+            msc4335_info_uri = limit_config.get("msc4335_info_uri", None)
+            msc4335_soft_limit = limit_config.get("msc4335_soft_limit", None)
+            msc4335_increase_uri = limit_config.get("msc4335_increase_uri", None)
 
-            self.media_upload_limits.append(MediaUploadLimit(max_bytes, time_period_ms))
+            if (
+                msc4335_info_uri is not None
+                or msc4335_soft_limit is not None
+                or msc4335_increase_uri is not None
+            ) and (not (msc4335_info_uri and msc4335_soft_limit is not None)):
+                raise ConfigError(
+                    "If any of msc4335_info_uri, msc4335_soft_limit or "
+                    "msc4335_increase_uri are set, then both msc4335_info_uri and "
+                    "msc4335_soft_limit must be set."
+                )
+            if msc4335_soft_limit and not msc4335_increase_uri:
+                raise ConfigError(
+                    "msc4335_increase_uri must be set if msc4335_soft_limit is true."
+                )
+
+            self.media_upload_limits.append(
+                MediaUploadLimit(
+                    max_bytes,
+                    time_period_ms,
+                    msc4335_info_uri,
+                    msc4335_soft_limit,
+                    msc4335_increase_uri,
+                )
+            )
 
     def generate_config_section(self, data_dir_path: str, **kwargs: Any) -> str:
         assert data_dir_path is not None

synapse/media/media_repository.py

@@ -37,6 +37,7 @@
     Codes,
     FederationDeniedError,
     HttpResponseException,
+    MSC4335UserLimitExceededError,
     NotFoundError,
     RequestSendFailed,
     SynapseError,
@@ -67,6 +68,7 @@
 from synapse.media.storage_provider import StorageProviderWrapper
 from synapse.media.thumbnailer import Thumbnailer, ThumbnailError
 from synapse.media.url_previewer import UrlPreviewer
+from synapse.rest.admin.experimental_features import ExperimentalFeature
 from synapse.storage.databases.main.media_repository import LocalMedia, RemoteMedia
 from synapse.types import UserID
 from synapse.util.async_helpers import Linearizer
@@ -379,6 +381,25 @@ async def create_or_update_content(
                     sent_bytes=uploaded_media_size,
                     attempted_bytes=content_length,
                 )
+                # If the MSC4335 experimental feature is enabled and the media limit
+                # has the info_uri configured then we raise the MSC4335 error
+                msc4335_enabled = await self.store.is_feature_enabled(
+                    auth_user.to_string(), ExperimentalFeature.MSC4335
+                )
+                if (
+                    msc4335_enabled
+                    and limit.msc4335_info_uri
+                    and limit.msc4335_soft_limit is not None
+                ):
+                    raise MSC4335UserLimitExceededError(
+                        403,
+                        "Media upload limit exceeded",
+                        limit.msc4335_info_uri,
+                        limit.msc4335_soft_limit,
+                        limit.msc4335_increase_uri,
+                    )
+                # Otherwise we use the current behaviour albeit not spec compliant
+                # See: https://github.com/element-hq/synapse/issues/18749
                 raise SynapseError(
                     400, "Media upload limit exceeded", Codes.RESOURCE_LIMIT_EXCEEDED
                 )

synapse/rest/admin/experimental_features.py

@@ -44,6 +44,7 @@ class ExperimentalFeature(str, Enum):
     MSC3881 = "msc3881"
     MSC3575 = "msc3575"
     MSC4222 = "msc4222"
+    MSC4335 = "msc4335"
 
     def is_globally_enabled(self, config: "HomeServerConfig") -> bool:
         if self is ExperimentalFeature.MSC3881:
@@ -52,6 +53,8 @@ def is_globally_enabled(self, config: "HomeServerConfig") -> bool:
             return config.experimental.msc3575_enabled
         if self is ExperimentalFeature.MSC4222:
             return config.experimental.msc4222_enabled
+        if self is ExperimentalFeature.MSC4335:
+            return config.experimental.msc4335_enabled
 
         assert_never(self)