Extend spam checker to allow for multiple modules (#7435)

synapse/events/spamcheck.py

@@ -15,7 +15,7 @@
 # limitations under the License.
 
 import inspect
-from typing import Dict
+from typing import Any, Dict, List
 
 from synapse.spam_checker_api import SpamCheckerApi
 
@@ -26,24 +26,17 @@ if MYPY:
 
 class SpamChecker(object):
     def __init__(self, hs: "synapse.server.HomeServer"):
-        self.spam_checker = None
+        self.spam_checkers = []  # type: List[Any]
 
-        module = None
-        config = None
-        try:
-            module, config = hs.config.spam_checker
-        except Exception:
-            pass
-
-        if module is not None:
+        for module, config in hs.config.spam_checkers:
             # Older spam checkers don't accept the `api` argument, so we
             # try and detect support.
             spam_args = inspect.getfullargspec(module)
             if "api" in spam_args.args:
                 api = SpamCheckerApi(hs)
-                self.spam_checker = module(config=config, api=api)
+                self.spam_checkers.append(module(config=config, api=api))
             else:
-                self.spam_checker = module(config=config)
+                self.spam_checkers.append(module(config=config))
 
     def check_event_for_spam(self, event: "synapse.events.EventBase") -> bool:
         """Checks if a given event is considered "spammy" by this server.
@@ -58,10 +51,11 @@ class SpamChecker(object):
         Returns:
             True if the event is spammy.
         """
-        if self.spam_checker is None:
-            return False
+        for spam_checker in self.spam_checkers:
+            if spam_checker.check_event_for_spam(event):
+                return True
 
-        return self.spam_checker.check_event_for_spam(event)
+        return False
 
     def user_may_invite(
         self, inviter_userid: str, invitee_userid: str, room_id: str
@@ -78,12 +72,14 @@ class SpamChecker(object):
         Returns:
             True if the user may send an invite, otherwise False
         """
-        if self.spam_checker is None:
-            return True
+        for spam_checker in self.spam_checkers:
+            if (
+                spam_checker.user_may_invite(inviter_userid, invitee_userid, room_id)
+                is False
+            ):
+                return False
 
-        return self.spam_checker.user_may_invite(
-            inviter_userid, invitee_userid, room_id
-        )
+        return True
 
     def user_may_create_room(self, userid: str) -> bool:
         """Checks if a given user may create a room
@@ -96,10 +92,11 @@ class SpamChecker(object):
         Returns:
             True if the user may create a room, otherwise False
         """
-        if self.spam_checker is None:
-            return True
+        for spam_checker in self.spam_checkers:
+            if spam_checker.user_may_create_room(userid) is False:
+                return False
 
-        return self.spam_checker.user_may_create_room(userid)
+        return True
 
     def user_may_create_room_alias(self, userid: str, room_alias: str) -> bool:
         """Checks if a given user may create a room alias
@@ -113,10 +110,11 @@ class SpamChecker(object):
         Returns:
             True if the user may create a room alias, otherwise False
         """
-        if self.spam_checker is None:
-            return True
+        for spam_checker in self.spam_checkers:
+            if spam_checker.user_may_create_room_alias(userid, room_alias) is False:
+                return False
 
-        return self.spam_checker.user_may_create_room_alias(userid, room_alias)
+        return True
 
     def user_may_publish_room(self, userid: str, room_id: str) -> bool:
         """Checks if a given user may publish a room to the directory
@@ -130,10 +128,11 @@ class SpamChecker(object):
         Returns:
             True if the user may publish the room, otherwise False
         """
-        if self.spam_checker is None:
-            return True
+        for spam_checker in self.spam_checkers:
+            if spam_checker.user_may_publish_room(userid, room_id) is False:
+                return False
 
-        return self.spam_checker.user_may_publish_room(userid, room_id)
+        return True
 
     def check_username_for_spam(self, user_profile: Dict[str, str]) -> bool:
         """Checks if a user ID or display name are considered "spammy" by this server.
@@ -150,13 +149,14 @@ class SpamChecker(object):
         Returns:
             True if the user is spammy.
         """
-        if self.spam_checker is None:
-            return False
+        for spam_checker in self.spam_checkers:
+            # For backwards compatibility, only run if the method exists on the
+            # spam checker
+            checker = getattr(spam_checker, "check_username_for_spam", None)
+            if checker:
+                # Make a copy of the user profile object to ensure the spam checker
+                # cannot modify it.
+                if checker(user_profile.copy()):
+                    return True
 
-        # For backwards compatibility, if the method does not exist on the spam checker, fallback to not interfering.
-        checker = getattr(self.spam_checker, "check_username_for_spam", None)
-        if not checker:
-            return False
-        # Make a copy of the user profile object to ensure the spam checker
-        # cannot modify it.
-        return checker(user_profile.copy())
+        return False