From 2cd9260500efa82713edd365f54d491ac0328fb0 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 17 Mar 2016 11:09:03 +0000
Subject: [PATCH 1/2] Update aliases event after deletion

Attempt to update the appropriate `m.room.aliases` event after deleting
an alias. This may fail due to the deleter not being in the room.

Will also check if the canonical alias of the event is set to the
deleted alias, and if so will attempt to delete it.
---
 synapse/handlers/directory.py       | 52 +++++++++++++++++++++++++----
 synapse/rest/client/v1/directory.py |  3 +-
 2 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index c4aaa119188c..be9f2a21b249 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -32,6 +32,8 @@ class DirectoryHandler(BaseHandler):
     def __init__(self, hs):
         super(DirectoryHandler, self).__init__(hs)
 
+        self.state = hs.get_state_handler()
+
         self.federation = hs.get_replication_layer()
         self.federation.register_query_handler(
             "directory", self.on_directory_query
@@ -93,7 +95,7 @@ def create_appservice_association(self, service, room_alias, room_id,
         yield self._create_association(room_alias, room_id, servers)
 
     @defer.inlineCallbacks
-    def delete_association(self, user_id, room_alias):
+    def delete_association(self, requester, user_id, room_alias):
         # association deletion for human users
 
         can_delete = yield self._user_can_delete_alias(room_alias, user_id)
@@ -112,7 +114,25 @@ def delete_association(self, user_id, room_alias):
                 errcode=Codes.EXCLUSIVE
             )
 
-        yield self._delete_association(room_alias)
+        room_id = yield self._delete_association(room_alias)
+
+        try:
+            yield self.send_room_alias_update_event(
+                requester,
+                requester.user.to_string(),
+                room_id
+            )
+
+            yield self._update_canonical_alias(
+                requester,
+                requester.user.to_string(),
+                room_id,
+                room_alias,
+            )
+        except AuthError as e:
+            logger.info("Failed to update alias events: %s", e)
+
+        defer.returnValue(room_id)
 
     @defer.inlineCallbacks
     def delete_appservice_association(self, service, room_alias):
@@ -129,11 +149,9 @@ def _delete_association(self, room_alias):
         if not self.hs.is_mine(room_alias):
             raise SynapseError(400, "Room alias must be local")
 
-        yield self.store.delete_room_alias(room_alias)
+        room_id = yield self.store.delete_room_alias(room_alias)
 
-        # TODO - Looks like _update_room_alias_event has never been implemented
-        # if room_id:
-        #    yield self._update_room_alias_events(user_id, room_id)
+        defer.returnValue(room_id)
 
     @defer.inlineCallbacks
     def get_association(self, room_alias):
@@ -233,6 +251,28 @@ def send_room_alias_update_event(self, requester, user_id, room_id):
             ratelimit=False
         )
 
+    @defer.inlineCallbacks
+    def _update_canonical_alias(self, requester, user_id, room_id, room_alias):
+        alias_event = yield self.state.get_current_state(
+            room_id, EventTypes.CanonicalAlias, ""
+        )
+
+        if alias_event.content.get("alias", "") != room_alias.to_string():
+            return
+
+        msg_handler = self.hs.get_handlers().message_handler
+        yield msg_handler.create_and_send_nonmember_event(
+            requester,
+            {
+                "type": EventTypes.CanonicalAlias,
+                "state_key": "",
+                "room_id": room_id,
+                "sender": user_id,
+                "content": {},
+            },
+            ratelimit=False
+        )
+
     @defer.inlineCallbacks
     def get_association_from_room_alias(self, room_alias):
         result = yield self.store.get_association_from_room_alias(
diff --git a/synapse/rest/client/v1/directory.py b/synapse/rest/client/v1/directory.py
index 60c5ec77aaa3..59a23d6cb64e 100644
--- a/synapse/rest/client/v1/directory.py
+++ b/synapse/rest/client/v1/directory.py
@@ -127,8 +127,9 @@ def on_DELETE(self, request, room_alias):
         room_alias = RoomAlias.from_string(room_alias)
 
         yield dir_handler.delete_association(
-            user.to_string(), room_alias
+            requester, user.to_string(), room_alias
         )
+
         logger.info(
             "User %s deleted alias %s",
             user.to_string(),

From 56aa4e7a9a6846a72e9031e29555b05ed119e679 Mon Sep 17 00:00:00 2001
From: Erik Johnston <erik@matrix.org>
Date: Thu, 17 Mar 2016 15:24:19 +0000
Subject: [PATCH 2/2] Check canonical alias event exists

---
 synapse/handlers/directory.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/synapse/handlers/directory.py b/synapse/handlers/directory.py
index be9f2a21b249..6bcc5a5e2bc8 100644
--- a/synapse/handlers/directory.py
+++ b/synapse/handlers/directory.py
@@ -257,7 +257,8 @@ def _update_canonical_alias(self, requester, user_id, room_id, room_alias):
             room_id, EventTypes.CanonicalAlias, ""
         )
 
-        if alias_event.content.get("alias", "") != room_alias.to_string():
+        alias_str = room_alias.to_string()
+        if not alias_event or alias_event.content.get("alias", "") != alias_str:
             return
 
         msg_handler = self.hs.get_handlers().message_handler