Fix checking whether a room can be published on creation. (#11392)

If `room_list_publication_rules` was configured with a rule with a
non-wildcard alias and a room was created with an alias then an
internal server error would have been thrown.

This fixes the error and properly applies the publication rules
during room creation.

4 files changed, 95 insertions, 56 deletions

diff --git a/changelog.d/11392.bugfix b/changelog.d/11392.bugfix
new file mode 100644
index 0000000000..fb15800327
--- /dev/null
+++ b/changelog.d/11392.bugfix
@@ -0,0 +1 @@
+Fix a bug introduced in v1.13.0 where creating and publishing a room could cause errors if `room_list_publication_rules` is configured.
diff --git a/synapse/config/room_directory.py b/synapse/config/room_directory.py
index 56981cac79..57316c59b6 100644
--- a/synapse/config/room_directory.py
+++ b/synapse/config/room_directory.py
@@ -1,4 +1,5 @@
 # Copyright 2018 New Vector Ltd
+# Copyright 2021 Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,6 +13,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from typing import List
+
+from synapse.types import JsonDict
 from synapse.util import glob_to_regex
 
 from ._base import Config, ConfigError
@@ -20,7 +24,7 @@ from ._base import Config, ConfigError
 class RoomDirectoryConfig(Config):
     section = "roomdirectory"
 
-    def read_config(self, config, **kwargs):
+    def read_config(self, config, **kwargs) -> None:
         self.enable_room_list_search = config.get("enable_room_list_search", True)
 
         alias_creation_rules = config.get("alias_creation_rules")
@@ -47,7 +51,7 @@ class RoomDirectoryConfig(Config):
                 _RoomDirectoryRule("room_list_publication_rules", {"action": "allow"})
             ]
 
-    def generate_config_section(self, config_dir_path, server_name, **kwargs):
+    def generate_config_section(self, config_dir_path, server_name, **kwargs) -> str:
         return """
         # Uncomment to disable searching the public room list. When disabled
         # blocks searching local and remote room lists for local and remote
@@ -113,16 +117,16 @@ class RoomDirectoryConfig(Config):
         #    action: allow
         """
 
-    def is_alias_creation_allowed(self, user_id, room_id, alias):
+    def is_alias_creation_allowed(self, user_id: str, room_id: str, alias: str) -> bool:
         """Checks if the given user is allowed to create the given alias
 
         Args:
-            user_id (str)
-            room_id (str)
-            alias (str)
+            user_id: The user to check.
+            room_id: The room ID for the alias.
+            alias: The alias being created.
 
         Returns:
-            boolean: True if user is allowed to create the alias
+            True if user is allowed to create the alias
         """
         for rule in self._alias_creation_rules:
             if rule.matches(user_id, room_id, [alias]):
@@ -130,16 +134,18 @@ class RoomDirectoryConfig(Config):
 
         return False
 
-    def is_publishing_room_allowed(self, user_id, room_id, aliases):
+    def is_publishing_room_allowed(
+        self, user_id: str, room_id: str, aliases: List[str]
+    ) -> bool:
         """Checks if the given user is allowed to publish the room
 
         Args:
-            user_id (str)
-            room_id (str)
-            aliases (list[str]): any local aliases associated with the room
+            user_id: The user ID publishing the room.
+            room_id: The room being published.
+            aliases: any local aliases associated with the room
 
         Returns:
-            boolean: True if user can publish room
+            True if user can publish room
         """
         for rule in self._room_list_publication_rules:
             if rule.matches(user_id, room_id, aliases):
@@ -153,11 +159,11 @@ class _RoomDirectoryRule:
     creating an alias or publishing a room.
     """
 
-    def __init__(self, option_name, rule):
+    def __init__(self, option_name: str, rule: JsonDict):
         """
         Args:
-            option_name (str): Name of the config option this rule belongs to
-            rule (dict): The rule as specified in the config
+            option_name: Name of the config option this rule belongs to
+            rule: The rule as specified in the config
         """
 
         action = rule["action"]
@@ -181,18 +187,18 @@ class _RoomDirectoryRule:
         except Exception as e:
             raise ConfigError("Failed to parse glob into regex") from e
 
-    def matches(self, user_id, room_id, aliases):
+    def matches(self, user_id: str, room_id: str, aliases: List[str]) -> bool:
         """Tests if this rule matches the given user_id, room_id and aliases.
 
         Args:
-            user_id (str)
-            room_id (str)
-            aliases (list[str]): The associated aliases to the room. Will be a
-                single element for testing alias creation, and can be empty for
-                testing room publishing.
+            user_id: The user ID to check.
+            room_id: The room ID to check.
+            aliases: The associated aliases to the room. Will be a single element
+                for testing alias creation, and can be empty for testing room
+                publishing.
 
         Returns:
-            boolean
+            True if the rule matches.
         """
 
         # Note: The regexes are anchored at both ends
diff --git a/synapse/handlers/room.py b/synapse/handlers/room.py
index f9a099c4f3..88053f9869 100644
--- a/synapse/handlers/room.py
+++ b/synapse/handlers/room.py
@@ -775,8 +775,11 @@ class RoomCreationHandler:
             raise SynapseError(403, "Room visibility value not allowed.")
 
         if is_public:
+            room_aliases = []
+            if room_alias:
+                room_aliases.append(room_alias.to_string())
             if not self.config.roomdirectory.is_publishing_room_allowed(
-                user_id, room_id, room_alias
+                user_id, room_id, room_aliases
             ):
                 # Let's just return a generic message, as there may be all sorts of
                 # reasons why we said no. TODO: Allow configurable error messages
diff --git a/tests/handlers/test_directory.py b/tests/handlers/test_directory.py
index be008227df..0ea4e753e2 100644
--- a/tests/handlers/test_directory.py
+++ b/tests/handlers/test_directory.py
@@ -1,4 +1,5 @@
 # Copyright 2014-2016 OpenMarket Ltd
+# Copyright 2021 Matrix.org Foundation C.I.C.
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -12,13 +13,11 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-
 from unittest.mock import Mock
 
 import synapse.api.errors
 import synapse.rest.admin
 from synapse.api.constants import EventTypes
-from synapse.config.room_directory import RoomDirectoryConfig
 from synapse.rest.client import directory, login, room
 from synapse.types import RoomAlias, create_requester
 
@@ -394,22 +393,15 @@ class TestCreateAliasACL(unittest.HomeserverTestCase):
 
     servlets = [directory.register_servlets, room.register_servlets]
 
-    def prepare(self, reactor, clock, hs):
-        # We cheekily override the config to add custom alias creation rules
-        config = {}
+    def default_config(self):
+        config = super().default_config()
+
+        # Add custom alias creation rules to the config.
         config["alias_creation_rules"] = [
             {"user_id": "*", "alias": "#unofficial_*", "action": "allow"}
         ]
-        config["room_list_publication_rules"] = []
 
-        rd_config = RoomDirectoryConfig()
-        rd_config.read_config(config)
-
-        self.hs.config.roomdirectory.is_alias_creation_allowed = (
-            rd_config.is_alias_creation_allowed
-        )
-
-        return hs
+        return config
 
     def test_denied(self):
         room_id = self.helper.create_room_as(self.user_id)
@@ -417,7 +409,7 @@ class TestCreateAliasACL(unittest.HomeserverTestCase):
         channel = self.make_request(
             "PUT",
             b"directory/room/%23test%3Atest",
-            ('{"room_id":"%s"}' % (room_id,)).encode("ascii"),
+            {"room_id": room_id},
         )
         self.assertEquals(403, channel.code, channel.result)
 
@@ -427,14 +419,35 @@ class TestCreateAliasACL(unittest.HomeserverTestCase):
         channel = self.make_request(
             "PUT",
             b"directory/room/%23unofficial_test%3Atest",
-            ('{"room_id":"%s"}' % (room_id,)).encode("ascii"),
+            {"room_id": room_id},
         )
         self.assertEquals(200, channel.code, channel.result)
 
+    def test_denied_during_creation(self):
+        """A room alias that is not allowed should be rejected during creation."""
+        # Invalid room alias.
+        self.helper.create_room_as(
+            self.user_id,
+            expect_code=403,
+            extra_content={"room_alias_name": "foo"},
+        )
 
-class TestCreatePublishedRoomACL(unittest.HomeserverTestCase):
-    data = {"room_alias_name": "unofficial_test"}
+    def test_allowed_during_creation(self):
+        """A valid room alias should be allowed during creation."""
+        room_id = self.helper.create_room_as(
+            self.user_id,
+            extra_content={"room_alias_name": "unofficial_test"},
+        )
 
+        channel = self.make_request(
+            "GET",
+            b"directory/room/%23unofficial_test%3Atest",
+        )
+        self.assertEquals(200, channel.code, channel.result)
+        self.assertEquals(channel.json_body["room_id"], room_id)
+
+
+class TestCreatePublishedRoomACL(unittest.HomeserverTestCase):
     servlets = [
         synapse.rest.admin.register_servlets_for_client_rest_resource,
         login.register_servlets,
@@ -443,27 +456,30 @@ class TestCreatePublishedRoomACL(unittest.HomeserverTestCase):
     ]
     hijack_auth = False
 
-    def prepare(self, reactor, clock, hs):
-        self.allowed_user_id = self.register_user("allowed", "pass")
-        self.allowed_access_token = self.login("allowed", "pass")
+    data = {"room_alias_name": "unofficial_test"}
+    allowed_localpart = "allowed"
 
-        self.denied_user_id = self.register_user("denied", "pass")
-        self.denied_access_token = self.login("denied", "pass")
+    def default_config(self):
+        config = super().default_config()
 
-        # This time we add custom room list publication rules
-        config = {}
-        config["alias_creation_rules"] = []
+        # Add custom room list publication rules to the config.
         config["room_list_publication_rules"] = [
+            {
+                "user_id": "@" + self.allowed_localpart + "*",
+                "alias": "#unofficial_*",
+                "action": "allow",
+            },
             {"user_id": "*", "alias": "*", "action": "deny"},
-            {"user_id": self.allowed_user_id, "alias": "*", "action": "allow"},
         ]
 
-        rd_config = RoomDirectoryConfig()
-        rd_config.read_config(config)
+        return config
 
-        self.hs.config.roomdirectory.is_publishing_room_allowed = (
-            rd_config.is_publishing_room_allowed
-        )
+    def prepare(self, reactor, clock, hs):
+        self.allowed_user_id = self.register_user(self.allowed_localpart, "pass")
+        self.allowed_access_token = self.login(self.allowed_localpart, "pass")
+
+        self.denied_user_id = self.register_user("denied", "pass")
+        self.denied_access_token = self.login("denied", "pass")
 
         return hs
 
@@ -505,10 +521,23 @@ class TestCreatePublishedRoomACL(unittest.HomeserverTestCase):
             self.allowed_user_id,
             tok=self.allowed_access_token,
             extra_content=self.data,
-            is_public=False,
+            is_public=True,
             expect_code=200,
         )
 
+    def test_denied_publication_with_invalid_alias(self):
+        """
+        Try to create a room, register an alias for it, and publish it,
+        as a user WITH permission to publish rooms.
+        """
+        self.helper.create_room_as(
+            self.allowed_user_id,
+            tok=self.allowed_access_token,
+            extra_content={"room_alias_name": "foo"},
+            is_public=True,
+            expect_code=403,
+        )
+
     def test_can_create_as_private_room_after_rejection(self):
         """
         After failing to publish a room with an alias as a user without publish permission,