Support optionally not sending read receipts to other users/servers

changelog.d/5990.feature

@@ -0,0 +1 @@
+Support a way for clients to not send read receipts to other users/servers.

synapse/app/federation_sender.py

@@ -262,6 +262,8 @@ def _on_new_receipts(self, rows):
             # we only want to send on receipts for our own users
             if not self._is_mine_id(receipt.user_id):
                 continue
+            if receipt.data.get("hidden", False):
+                return  # do not send over federation
             receipt_info = ReadReceipt(
                 receipt.room_id,
                 receipt.receipt_type,

synapse/handlers/initial_sync.py

@@ -395,7 +395,12 @@ def get_receipts():
             )
             if not receipts:
                 receipts = []
-            return receipts
+
+            return [
+                r
+                for r in receipts
+                if not r.data.get("hidden", False) or r.user_id == user_id
+            ]
 
         presence, receipts, (messages, token) = yield make_deferred_yieldable(
             defer.gatherResults(

synapse/handlers/receipts.py

@@ -106,7 +106,7 @@ def _handle_new_receipts(self, receipts):
         return True
 
     @defer.inlineCallbacks
-    def received_client_receipt(self, room_id, receipt_type, user_id, event_id):
+    def received_client_receipt(self, room_id, receipt_type, user_id, event_id, hidden):
         """Called when a client tells us a local user has read up to the given
         event_id in the room.
         """
@@ -115,14 +115,15 @@ def received_client_receipt(self, room_id, receipt_type, user_id, event_id):
             receipt_type=receipt_type,
             user_id=user_id,
             event_ids=[event_id],
-            data={"ts": int(self.clock.time_msec())},
+            data={"ts": int(self.clock.time_msec()), "hidden": hidden},
         )
 
         is_new = yield self._handle_new_receipts([receipt])
         if not is_new:
             return
 
-        yield self.federation.send_read_receipt(receipt)
+        if not hidden:
+            yield self.federation.send_read_receipt(receipt)
 
     @defer.inlineCallbacks
     def get_receipts_for_room(self, room_id, to_key):

synapse/handlers/sync.py

@@ -334,6 +334,7 @@ def ephemeral_by_room(self, sync_result_builder, now_token, since_token=None):
         """
 
         sync_config = sync_result_builder.sync_config
+        user_id = sync_result_builder.sync_config.user.to_string()
 
         with Measure(self.clock, "ephemeral_by_room"):
             typing_key = since_token.typing_key if since_token else "0"
@@ -376,7 +377,33 @@ def ephemeral_by_room(self, sync_result_builder, now_token, since_token=None):
                 room_id = event["room_id"]
                 # exclude room id, as above
                 event_copy = {k: v for (k, v) in iteritems(event) if k != "room_id"}
-                ephemeral_by_room.setdefault(room_id, []).append(event_copy)
+
+                # filter out receipts the user shouldn't see
+                content = event_copy.get("content", {})
+                event_ids = content.keys()
+                reconstructed = event_copy.copy()
+                reconstructed["content"] = {}  # clear old content
+                for event_id in event_ids:
+                    m_read = content[event_id].get("m.read", None)
+                    if m_read is None:
+                        # clone it now - it's not something we can process
+                        reconstructed["content"][event_id] = content[event_id]
+                        continue
+                    user_ids = m_read.keys()
+                    for rr_user_id in user_ids:
+                        data = m_read[rr_user_id]
+                        hidden = data.get("hidden", False)
+                        if rr_user_id == user_id or not hidden:
+                            # append the key to the reconstructed receipt
+                            new_content = reconstructed["content"]
+                            if new_content.get(event_id, None) is None:
+                                new_content[event_id] = {"m.read": {}}
+                            ev_content = new_content[event_id]["m.read"]
+                            if ev_content.get(rr_user_id, None) is None:
+                                ev_content[rr_user_id] = {}
+                            ev_content[rr_user_id] = data
+                if len(reconstructed["content"].keys()) > 0:
+                    ephemeral_by_room.setdefault(room_id, []).append(reconstructed)
 
         return now_token, ephemeral_by_room
 

synapse/rest/client/v2_alpha/read_marker.py

@@ -49,6 +49,7 @@ def on_POST(self, request, room_id):
                 "m.read",
                 user_id=requester.user.to_string(),
                 event_id=read_event_id,
+                hidden=body.get("m.hidden", False),
             )
 
         read_marker_event_id = body.get("m.fully_read", None)

synapse/rest/client/v2_alpha/receipts.py

@@ -18,7 +18,7 @@
 from twisted.internet import defer
 
 from synapse.api.errors import SynapseError
-from synapse.http.servlet import RestServlet
+from synapse.http.servlet import RestServlet, parse_json_object_from_request
 
 from ._base import client_patterns
 
@@ -46,10 +46,16 @@ def on_POST(self, request, room_id, receipt_type, event_id):
         if receipt_type != "m.read":
             raise SynapseError(400, "Receipt type must be 'm.read'")
 
+        body = parse_json_object_from_request(request)
+
         yield self.presence_handler.bump_presence_active_time(requester.user)
 
         yield self.receipts_handler.received_client_receipt(
-            room_id, receipt_type, user_id=requester.user.to_string(), event_id=event_id
+            room_id,
+            receipt_type,
+            user_id=requester.user.to_string(),
+            event_id=event_id,
+            hidden=body.get("m.hidden", False),
         )
 
         return 200, {}