Allow guests to register and call /events?room_id=

This follows the same flows-based flow as regular registration, but as
the only implemented flow has no requirements, it auto-succeeds. In the
future, other flows (e.g. captcha) may be required, so clients should
treat this like the regular registration flow choices.

4 files changed, 83 insertions, 55 deletions

diff --git a/synapse/handlers/_base.py b/synapse/handlers/_base.py
index 6a26cb1879..6873a4575d 100644
--- a/synapse/handlers/_base.py
+++ b/synapse/handlers/_base.py
@@ -47,37 +47,23 @@ class BaseHandler(object):
         self.event_builder_factory = hs.get_event_builder_factory()
 
     @defer.inlineCallbacks
-    def _filter_events_for_client(self, user_id, events):
-        event_id_to_state = yield self.store.get_state_for_events(
-            frozenset(e.event_id for e in events),
-            types=(
-                (EventTypes.RoomHistoryVisibility, ""),
-                (EventTypes.Member, user_id),
-            )
-        )
+    def _filter_events_for_client(self, user_id, events, is_guest=False):
+        # Assumes that user has at some point joined the room if not is_guest.
 
-        def allowed(event, state):
-            if event.type == EventTypes.RoomHistoryVisibility:
+        def allowed(event, membership, visibility):
+            if visibility == "world_readable":
                 return True
 
-            membership_ev = state.get((EventTypes.Member, user_id), None)
-            if membership_ev:
-                membership = membership_ev.membership
-            else:
-                membership = Membership.LEAVE
+            if is_guest:
+                return False
 
             if membership == Membership.JOIN:
                 return True
 
-            history = state.get((EventTypes.RoomHistoryVisibility, ''), None)
-            if history:
-                visibility = history.content.get("history_visibility", "shared")
-            else:
-                visibility = "shared"
+            if event.type == EventTypes.RoomHistoryVisibility:
+                return not is_guest
 
-            if visibility == "public":
-                return True
-            elif visibility == "shared":
+            if visibility == "shared":
                 return True
             elif visibility == "joined":
                 return membership == Membership.JOIN
@@ -86,11 +72,44 @@ class BaseHandler(object):
 
             return True
 
-        defer.returnValue([
-            event
-            for event in events
-            if allowed(event, event_id_to_state[event.event_id])
-        ])
+        event_id_to_state = yield self.store.get_state_for_events(
+            frozenset(e.event_id for e in events),
+            types=(
+                (EventTypes.RoomHistoryVisibility, ""),
+                (EventTypes.Member, user_id),
+            )
+        )
+
+        events_to_return = []
+        for event in events:
+            state = event_id_to_state[event.event_id]
+
+            membership_event = state.get((EventTypes.Member, user_id), None)
+            if membership_event:
+                membership = membership_event.membership
+            else:
+                membership = None
+
+            visibility_event = state.get((EventTypes.RoomHistoryVisibility, ""), None)
+            if visibility_event:
+                visibility = visibility_event.content.get("history_visibility", "shared")
+            else:
+                visibility = "shared"
+
+            should_include = allowed(event, membership, visibility)
+            if should_include:
+                events_to_return.append(event)
+
+        if is_guest and len(events_to_return) < len(events):
+            # This indicates that some events in the requested range were not
+            # visible to guest users. To be safe, we reject the entire request,
+            # so that we don't have to worry about interpreting visibility
+            # boundaries.
+            raise AuthError(403, "User %s does not have permission" % (
+                user_id
+            ))
+
+        defer.returnValue(events_to_return)
 
     def ratelimit(self, user_id):
         time_now = self.clock.time()
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 055d395b20..1b11dbdffd 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -372,12 +372,15 @@ class AuthHandler(BaseHandler):
         yield self.store.add_refresh_token_to_user(user_id, refresh_token)
         defer.returnValue(refresh_token)
 
-    def generate_access_token(self, user_id):
+    def generate_access_token(self, user_id, extra_caveats=None):
+        extra_caveats = extra_caveats or []
         macaroon = self._generate_base_macaroon(user_id)
         macaroon.add_first_party_caveat("type = access")
         now = self.hs.get_clock().time_msec()
         expiry = now + (60 * 60 * 1000)
         macaroon.add_first_party_caveat("time < %d" % (expiry,))
+        for caveat in extra_caveats:
+            macaroon.add_first_party_caveat(caveat)
         return macaroon.serialize()
 
     def generate_refresh_token(self, user_id):
diff --git a/synapse/handlers/message.py b/synapse/handlers/message.py
index 0f947993d1..687e1527f7 100644
--- a/synapse/handlers/message.py
+++ b/synapse/handlers/message.py
@@ -71,20 +71,20 @@ class MessageHandler(BaseHandler):
 
     @defer.inlineCallbacks
     def get_messages(self, user_id=None, room_id=None, pagin_config=None,
-                     as_client_event=True):
+                     as_client_event=True, is_guest=False):
         """Get messages in a room.
 
         Args:
             user_id (str): The user requesting messages.
             room_id (str): The room they want messages from.
             pagin_config (synapse.api.streams.PaginationConfig): The pagination
-            config rules to apply, if any.
+                config rules to apply, if any.
             as_client_event (bool): True to get events in client-server format.
+            is_guest (bool): Whether the requesting user is a guest (as opposed
+                to a fully registered user).
         Returns:
             dict: Pagination API results
         """
-        member_event = yield self.auth.check_user_was_in_room(room_id, user_id)
-
         data_source = self.hs.get_event_sources().sources["room"]
 
         if pagin_config.from_token:
@@ -107,23 +107,27 @@ class MessageHandler(BaseHandler):
 
         source_config = pagin_config.get_source_config("room")
 
-        if member_event.membership == Membership.LEAVE:
-            # If they have left the room then clamp the token to be before
-            # they left the room
-            leave_token = yield self.store.get_topological_token_for_event(
-                member_event.event_id
-            )
-            leave_token = RoomStreamToken.parse(leave_token)
-            if leave_token.topological < room_token.topological:
-                source_config.from_key = str(leave_token)
-
-            if source_config.direction == "f":
-                if source_config.to_key is None:
-                    source_config.to_key = str(leave_token)
-                else:
-                    to_token = RoomStreamToken.parse(source_config.to_key)
-                    if leave_token.topological < to_token.topological:
+        if not is_guest:
+            member_event = yield self.auth.check_user_was_in_room(room_id, user_id)
+            if member_event.membership == Membership.LEAVE:
+                # If they have left the room then clamp the token to be before
+                # they left the room.
+                # If they're a guest, we'll just 403 them if they're asking for
+                # events they can't see.
+                leave_token = yield self.store.get_topological_token_for_event(
+                    member_event.event_id
+                )
+                leave_token = RoomStreamToken.parse(leave_token)
+                if leave_token.topological < room_token.topological:
+                    source_config.from_key = str(leave_token)
+
+                if source_config.direction == "f":
+                    if source_config.to_key is None:
                         source_config.to_key = str(leave_token)
+                    else:
+                        to_token = RoomStreamToken.parse(source_config.to_key)
+                        if leave_token.topological < to_token.topological:
+                            source_config.to_key = str(leave_token)
 
         yield self.hs.get_handlers().federation_handler.maybe_backfill(
             room_id, room_token.topological
@@ -146,7 +150,7 @@ class MessageHandler(BaseHandler):
                 "end": next_token.to_string(),
             })
 
-        events = yield self._filter_events_for_client(user_id, events)
+        events = yield self._filter_events_for_client(user_id, events, is_guest=is_guest)
 
         time_now = self.clock.time_msec()
 
diff --git a/synapse/handlers/register.py b/synapse/handlers/register.py
index ef4081e3fe..493a087031 100644
--- a/synapse/handlers/register.py
+++ b/synapse/handlers/register.py
@@ -64,7 +64,7 @@ class RegistrationHandler(BaseHandler):
             )
 
     @defer.inlineCallbacks
-    def register(self, localpart=None, password=None):
+    def register(self, localpart=None, password=None, generate_token=True):
         """Registers a new client on the server.
 
         Args:
@@ -89,7 +89,9 @@ class RegistrationHandler(BaseHandler):
             user = UserID(localpart, self.hs.hostname)
             user_id = user.to_string()
 
-            token = self.auth_handler().generate_access_token(user_id)
+            token = None
+            if generate_token:
+                token = self.auth_handler().generate_access_token(user_id)
             yield self.store.register(
                 user_id=user_id,
                 token=token,
@@ -102,14 +104,14 @@ class RegistrationHandler(BaseHandler):
             attempts = 0
             user_id = None
             token = None
-            while not user_id and not token:
+            while not user_id:
                 try:
                     localpart = self._generate_user_id()
                     user = UserID(localpart, self.hs.hostname)
                     user_id = user.to_string()
                     yield self.check_user_id_is_valid(user_id)
-
-                    token = self.auth_handler().generate_access_token(user_id)
+                    if generate_token:
+                        token = self.auth_handler().generate_access_token(user_id)
                     yield self.store.register(
                         user_id=user_id,
                         token=token,