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.

1 files changed, 54 insertions, 41 deletions

diff --git a/synapse/api/auth.py b/synapse/api/auth.py
index 88445fe999..dfbbc5a1cd 100644
--- a/synapse/api/auth.py
+++ b/synapse/api/auth.py
@@ -49,6 +49,7 @@ class Auth(object):
         self.TOKEN_NOT_FOUND_HTTP_STATUS = 401
         self._KNOWN_CAVEAT_PREFIXES = set([
             "gen = ",
+            "guest = ",
             "type = ",
             "time < ",
             "user_id = ",
@@ -183,15 +184,11 @@ class Auth(object):
         defer.returnValue(member)
 
     @defer.inlineCallbacks
-    def check_user_was_in_room(self, room_id, user_id, current_state=None):
+    def check_user_was_in_room(self, room_id, user_id):
         """Check if the user was in the room at some point.
         Args:
             room_id(str): The room to check.
             user_id(str): The user to check.
-            current_state(dict): Optional map of the current state of the room.
-                If provided then that map is used to check whether they are a
-                member of the room. Otherwise the current membership is
-                loaded from the database.
         Raises:
             AuthError if the user was never in the room.
         Returns:
@@ -199,17 +196,11 @@ class Auth(object):
             room. This will be the join event if they are currently joined to
             the room. This will be the leave event if they have left the room.
         """
-        if current_state:
-            member = current_state.get(
-                (EventTypes.Member, user_id),
-                None
-            )
-        else:
-            member = yield self.state.get_current_state(
-                room_id=room_id,
-                event_type=EventTypes.Member,
-                state_key=user_id
-            )
+        member = yield self.state.get_current_state(
+            room_id=room_id,
+            event_type=EventTypes.Member,
+            state_key=user_id
+        )
         membership = member.membership if member else None
 
         if membership not in (Membership.JOIN, Membership.LEAVE):
@@ -497,7 +488,7 @@ class Auth(object):
             return default
 
     @defer.inlineCallbacks
-    def get_user_by_req(self, request):
+    def get_user_by_req(self, request, allow_guest=False):
         """ Get a registered user's ID.
 
         Args:
@@ -535,7 +526,7 @@ class Auth(object):
 
                 request.authenticated_entity = user_id
 
-                defer.returnValue((UserID.from_string(user_id), ""))
+                defer.returnValue((UserID.from_string(user_id), "", False))
                 return
             except KeyError:
                 pass  # normal users won't have the user_id query parameter set.
@@ -543,6 +534,7 @@ class Auth(object):
             user_info = yield self._get_user_by_access_token(access_token)
             user = user_info["user"]
             token_id = user_info["token_id"]
+            is_guest = user_info["is_guest"]
 
             ip_addr = self.hs.get_ip_from_request(request)
             user_agent = request.requestHeaders.getRawHeaders(
@@ -557,9 +549,14 @@ class Auth(object):
                     user_agent=user_agent
                 )
 
+            if is_guest and not allow_guest:
+                raise AuthError(
+                    403, "Guest access not allowed", errcode=Codes.GUEST_ACCESS_FORBIDDEN
+                )
+
             request.authenticated_entity = user.to_string()
 
-            defer.returnValue((user, token_id,))
+            defer.returnValue((user, token_id, is_guest,))
         except KeyError:
             raise AuthError(
                 self.TOKEN_NOT_FOUND_HTTP_STATUS, "Missing access token.",
@@ -592,31 +589,45 @@ class Auth(object):
             self._validate_macaroon(macaroon)
 
             user_prefix = "user_id = "
+            user = None
+            guest = False
             for caveat in macaroon.caveats:
                 if caveat.caveat_id.startswith(user_prefix):
                     user = UserID.from_string(caveat.caveat_id[len(user_prefix):])
-                    # This codepath exists so that we can actually return a
-                    # token ID, because we use token IDs in place of device
-                    # identifiers throughout the codebase.
-                    # TODO(daniel): Remove this fallback when device IDs are
-                    # properly implemented.
-                    ret = yield self._look_up_user_by_access_token(macaroon_str)
-                    if ret["user"] != user:
-                        logger.error(
-                            "Macaroon user (%s) != DB user (%s)",
-                            user,
-                            ret["user"]
-                        )
-                        raise AuthError(
-                            self.TOKEN_NOT_FOUND_HTTP_STATUS,
-                            "User mismatch in macaroon",
-                            errcode=Codes.UNKNOWN_TOKEN
-                        )
-                    defer.returnValue(ret)
-            raise AuthError(
-                self.TOKEN_NOT_FOUND_HTTP_STATUS, "No user caveat in macaroon",
-                errcode=Codes.UNKNOWN_TOKEN
-            )
+                elif caveat.caveat_id == "guest = true":
+                    guest = True
+
+            if user is None:
+                raise AuthError(
+                    self.TOKEN_NOT_FOUND_HTTP_STATUS, "No user caveat in macaroon",
+                    errcode=Codes.UNKNOWN_TOKEN
+                )
+
+            if guest:
+                ret = {
+                    "user": user,
+                    "is_guest": True,
+                    "token_id": None,
+                }
+            else:
+                # This codepath exists so that we can actually return a
+                # token ID, because we use token IDs in place of device
+                # identifiers throughout the codebase.
+                # TODO(daniel): Remove this fallback when device IDs are
+                # properly implemented.
+                ret = yield self._look_up_user_by_access_token(macaroon_str)
+                if ret["user"] != user:
+                    logger.error(
+                        "Macaroon user (%s) != DB user (%s)",
+                        user,
+                        ret["user"]
+                    )
+                    raise AuthError(
+                        self.TOKEN_NOT_FOUND_HTTP_STATUS,
+                        "User mismatch in macaroon",
+                        errcode=Codes.UNKNOWN_TOKEN
+                    )
+            defer.returnValue(ret)
         except (pymacaroons.exceptions.MacaroonException, TypeError, ValueError):
             raise AuthError(
                 self.TOKEN_NOT_FOUND_HTTP_STATUS, "Invalid macaroon passed.",
@@ -629,6 +640,7 @@ class Auth(object):
         v.satisfy_exact("type = access")
         v.satisfy_general(lambda c: c.startswith("user_id = "))
         v.satisfy_general(self._verify_expiry)
+        v.satisfy_exact("guest = true")
         v.verify(macaroon, self.hs.config.macaroon_secret_key)
 
         v = pymacaroons.Verifier()
@@ -666,6 +678,7 @@ class Auth(object):
         user_info = {
             "user": UserID.from_string(ret.get("name")),
             "token_id": ret.get("token_id", None),
+            "is_guest": False,
         }
         defer.returnValue(user_info)