Add federation_domain_whitelist option (#2820)

Add federation_domain_whitelist

gives a way to restrict which domains your HS is allowed to federate with.
useful mainly for gracefully preventing a private but internet-connected HS from trying to federate to the wider public Matrix network

1 files changed, 17 insertions, 2 deletions

diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 4f56bcf577..485db8577a 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -32,8 +32,9 @@ from .media_storage import MediaStorage
 
 from synapse.http.matrixfederationclient import MatrixFederationHttpClient
 from synapse.util.stringutils import random_string
-from synapse.api.errors import SynapseError, HttpResponseException, \
-    NotFoundError
+from synapse.api.errors import (
+    SynapseError, HttpResponseException, NotFoundError, FederationDeniedError,
+)
 
 from synapse.util.async import Linearizer
 from synapse.util.stringutils import is_ascii
@@ -75,6 +76,8 @@ class MediaRepository(object):
         self.recently_accessed_remotes = set()
         self.recently_accessed_locals = set()
 
+        self.federation_domain_whitelist = hs.config.federation_domain_whitelist
+
         # List of StorageProviders where we should search for media and
         # potentially upload to.
         storage_providers = []
@@ -216,6 +219,12 @@ class MediaRepository(object):
             Deferred: Resolves once a response has successfully been written
                 to request
         """
+        if (
+            self.federation_domain_whitelist is not None and
+            server_name not in self.federation_domain_whitelist
+        ):
+            raise FederationDeniedError(server_name)
+
         self.mark_recently_accessed(server_name, media_id)
 
         # We linearize here to ensure that we don't try and download remote
@@ -250,6 +259,12 @@ class MediaRepository(object):
         Returns:
             Deferred[dict]: The media_info of the file
         """
+        if (
+            self.federation_domain_whitelist is not None and
+            server_name not in self.federation_domain_whitelist
+        ):
+            raise FederationDeniedError(server_name)
+
         # We linearize here to ensure that we don't try and download remote
         # media multiple times concurrently
         key = (server_name, media_id)