Merge pull request #4051 from matrix-org/erikj/alias_disallow_list

Add config option to control alias creation

2 files changed, 104 insertions, 1 deletions

diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index b8d5690f2b..10dd40159f 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -31,6 +31,7 @@ from .push import PushConfig
 from .ratelimiting import RatelimitConfig
 from .registration import RegistrationConfig
 from .repository import ContentRepositoryConfig
+from .room_directory import RoomDirectoryConfig
 from .saml2 import SAML2Config
 from .server import ServerConfig
 from .server_notices_config import ServerNoticesConfig
@@ -49,7 +50,7 @@ class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
                        WorkerConfig, PasswordAuthProviderConfig, PushConfig,
                        SpamCheckerConfig, GroupsConfig, UserDirectoryConfig,
                        ConsentConfig,
-                       ServerNoticesConfig,
+                       ServerNoticesConfig, RoomDirectoryConfig,
                        ):
     pass
 
diff --git a/synapse/config/room_directory.py b/synapse/config/room_directory.py
new file mode 100644
index 0000000000..9da13ab11b
--- /dev/null
+++ b/synapse/config/room_directory.py
@@ -0,0 +1,102 @@
+# -*- coding: utf-8 -*-
+# Copyright 2018 New Vector Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from synapse.util import glob_to_regex
+
+from ._base import Config, ConfigError
+
+
+class RoomDirectoryConfig(Config):
+    def read_config(self, config):
+        alias_creation_rules = config["alias_creation_rules"]
+
+        self._alias_creation_rules = [
+            _AliasRule(rule)
+            for rule in alias_creation_rules
+        ]
+
+    def default_config(self, config_dir_path, server_name, **kwargs):
+        return """
+        # The `alias_creation` option controls who's allowed to create aliases
+        # on this server.
+        #
+        # The format of this option is a list of rules that contain globs that
+        # match against user_id and the new alias (fully qualified with server
+        # name). The action in the first rule that matches is taken, which can
+        # currently either be "allow" or "deny".
+        #
+        # If no rules match the request is denied.
+        alias_creation_rules:
+            - user_id: "*"
+              alias: "*"
+              action: allow
+        """
+
+    def is_alias_creation_allowed(self, user_id, alias):
+        """Checks if the given user is allowed to create the given alias
+
+        Args:
+            user_id (str)
+            alias (str)
+
+        Returns:
+            boolean: True if user is allowed to crate the alias
+        """
+        for rule in self._alias_creation_rules:
+            if rule.matches(user_id, alias):
+                return rule.action == "allow"
+
+        return False
+
+
+class _AliasRule(object):
+    def __init__(self, rule):
+        action = rule["action"]
+        user_id = rule["user_id"]
+        alias = rule["alias"]
+
+        if action in ("allow", "deny"):
+            self.action = action
+        else:
+            raise ConfigError(
+                "alias_creation_rules rules can only have action of 'allow'"
+                " or 'deny'"
+            )
+
+        try:
+            self._user_id_regex = glob_to_regex(user_id)
+            self._alias_regex = glob_to_regex(alias)
+        except Exception as e:
+            raise ConfigError("Failed to parse glob into regex: %s", e)
+
+    def matches(self, user_id, alias):
+        """Tests if this rule matches the given user_id and alias.
+
+        Args:
+            user_id (str)
+            alias (str)
+
+        Returns:
+            boolean
+        """
+
+        # Note: The regexes are anchored at both ends
+        if not self._user_id_regex.match(user_id):
+            return False
+
+        if not self._alias_regex.match(alias):
+            return False
+
+        return True