Only setdefault for signatures if device has key_json (#7177)

If there was an exception setting up one of the attributes of the Homeserver
god object, then future attempts to fetch that attribute would raise a
confusing "Cyclic dependency" error. Let's make sure that we clear the
`building` flag so that we just get the original exception.

Ref: #7169

changelog.d/7177.bugfix

@@ -0,0 +1 @@
+Fix a bug which could cause outbound federation traffic to stop working if a client uploaded an incorrect e2e device signature.

changelog.d/7178.bugfix

@@ -0,0 +1 @@
+Fix a bug which could cause incorrect 'cyclic dependency' error.

changelog.d/7184.misc

@@ -0,0 +1 @@
+Convert some of synapse.rest.media to async/await.

synapse/server.py

@@ -583,25 +583,23 @@ def _make_dependency_method(depname):
         try:
             builder = getattr(hs, "build_%s" % (depname))
         except AttributeError:
-            builder = None
-
-        if builder:
-            # Prevent cyclic dependencies from deadlocking
-            if depname in hs._building:
-                raise ValueError("Cyclic dependency while building %s" % (depname,))
-            hs._building[depname] = 1
-
-            dep = builder()
-            setattr(hs, depname, dep)
-
-            del hs._building[depname]
-
-            return dep
-
             raise NotImplementedError(
                 "%s has no %s nor a builder for it" % (type(hs).__name__, depname)
             )
 
+        # Prevent cyclic dependencies from deadlocking
+        if depname in hs._building:
+            raise ValueError("Cyclic dependency while building %s" % (depname,))
+
+        hs._building[depname] = 1
+        try:
+            dep = builder()
+            setattr(hs, depname, dep)
+        finally:
+            del hs._building[depname]
+
+        return dep
+
     setattr(HomeServer, "get_%s" % (depname), _get)
 
 

synapse/storage/data_stores/main/devices.py

@@ -286,14 +286,16 @@ class DeviceWorkerStore(SQLBaseStore):
                     key_json = device.get("key_json", None)
                     if key_json:
                         result["keys"] = db_to_json(key_json)
-                    device_display_name = device.get("device_display_name", None)
-                    if device_display_name:
-                        result["device_display_name"] = device_display_name
+
                         if "signatures" in device:
                             for sig_user_id, sigs in device["signatures"].items():
                                 result["keys"].setdefault("signatures", {}).setdefault(
                                     sig_user_id, {}
                                 ).update(sigs)
+
+                    device_display_name = device.get("device_display_name", None)
+                    if device_display_name:
+                        result["device_display_name"] = device_display_name
                 else:
                     result["deleted"] = True
 
@@ -494,15 +496,17 @@ class DeviceWorkerStore(SQLBaseStore):
                 key_json = device.get("key_json", None)
                 if key_json:
                     result["keys"] = db_to_json(key_json)
-                device_display_name = device.get("device_display_name", None)
-                if device_display_name:
-                    result["device_display_name"] = device_display_name
+
                     if "signatures" in device:
                         for sig_user_id, sigs in device["signatures"].items():
                             result["keys"].setdefault("signatures", {}).setdefault(
                                 sig_user_id, {}
                             ).update(sigs)
 
+                device_display_name = device.get("device_display_name", None)
+                if device_display_name:
+                    result["device_display_name"] = device_display_name
+
                 results.append(result)
 
             return now_stream_id, results

synapse/storage/data_stores/main/media_repository.py

@@ -340,7 +340,7 @@ class MediaRepositoryStore(MediaRepositoryBackgroundUpdateStore):
             "get_expired_url_cache", _get_expired_url_cache_txn
         )
 
-    def delete_url_cache(self, media_ids):
+    async def delete_url_cache(self, media_ids):
         if len(media_ids) == 0:
             return
 
@@ -349,7 +349,7 @@ class MediaRepositoryStore(MediaRepositoryBackgroundUpdateStore):
         def _delete_url_cache_txn(txn):
             txn.executemany(sql, [(media_id,) for media_id in media_ids])
 
-        return self.db.runInteraction("delete_url_cache", _delete_url_cache_txn)
+        return await self.db.runInteraction("delete_url_cache", _delete_url_cache_txn)
 
     def get_url_cache_media_before(self, before_ts):
         sql = (