Add a cache around server ACL checking (#16360)

* Pre-compiles the server ACLs onto an object per room and
  invalidates them when new events come in.
* Converts the server ACL checking into Rust.

1 files changed, 6 insertions, 70 deletions

diff --git a/synapse/federation/federation_server.py b/synapse/federation/federation_server.py

index f9915e5a3f..ec8e770430 100644
--- a/synapse/federation/federation_server.py
+++ b/synapse/federation/federation_server.py
@@ -29,10 +29,8 @@ from typing import (
     Union,
 )
 
-from matrix_common.regex import glob_to_regex
 from prometheus_client import Counter, Gauge, Histogram
 
-from twisted.internet.abstract import isIPAddress
 from twisted.python import failure
 
 from synapse.api.constants import (
@@ -1324,75 +1322,13 @@ class FederationServer(FederationBase):
         Raises:
             AuthError if the server does not match the ACL
         """
-        acl_event = await self._storage_controllers.state.get_current_state_event(
-            room_id, EventTypes.ServerACL, ""
+        server_acl_evaluator = (
+            await self._storage_controllers.state.get_server_acl_for_room(room_id)
         )
-        if not acl_event or server_matches_acl_event(server_name, acl_event):
-            return
-
-        raise AuthError(code=403, msg="Server is banned from room")
-
-
-def server_matches_acl_event(server_name: str, acl_event: EventBase) -> bool:
-    """Check if the given server is allowed by the ACL event
-
-    Args:
-        server_name: name of server, without any port part
-        acl_event: m.room.server_acl event
-
-    Returns:
-        True if this server is allowed by the ACLs
-    """
-    logger.debug("Checking %s against acl %s", server_name, acl_event.content)
-
-    # first of all, check if literal IPs are blocked, and if so, whether the
-    # server name is a literal IP
-    allow_ip_literals = acl_event.content.get("allow_ip_literals", True)
-    if not isinstance(allow_ip_literals, bool):
-        logger.warning("Ignoring non-bool allow_ip_literals flag")
-        allow_ip_literals = True
-    if not allow_ip_literals:
-        # check for ipv6 literals. These start with '['.
-        if server_name[0] == "[":
-            return False
-
-        # check for ipv4 literals. We can just lift the routine from twisted.
-        if isIPAddress(server_name):
-            return False
-
-    # next,  check the deny list
-    deny = acl_event.content.get("deny", [])
-    if not isinstance(deny, (list, tuple)):
-        logger.warning("Ignoring non-list deny ACL %s", deny)
-        deny = []
-    for e in deny:
-        if _acl_entry_matches(server_name, e):
-            # logger.info("%s matched deny rule %s", server_name, e)
-            return False
-
-    # then the allow list.
-    allow = acl_event.content.get("allow", [])
-    if not isinstance(allow, (list, tuple)):
-        logger.warning("Ignoring non-list allow ACL %s", allow)
-        allow = []
-    for e in allow:
-        if _acl_entry_matches(server_name, e):
-            # logger.info("%s matched allow rule %s", server_name, e)
-            return True
-
-    # everything else should be rejected.
-    # logger.info("%s fell through", server_name)
-    return False
-
-
-def _acl_entry_matches(server_name: str, acl_entry: Any) -> bool:
-    if not isinstance(acl_entry, str):
-        logger.warning(
-            "Ignoring non-str ACL entry '%s' (is %s)", acl_entry, type(acl_entry)
-        )
-        return False
-    regex = glob_to_regex(acl_entry)
-    return bool(regex.match(server_name))
+        if server_acl_evaluator and not server_acl_evaluator.server_matches_acl_event(
+            server_name
+        ):
+            raise AuthError(code=403, msg="Server is banned from room")
 
 
 class FederationHandlerRegistry: