From 14ed6799d72c7807467456808aa08a6f376ebe14 Mon Sep 17 00:00:00 2001
From: David Baker <dbkr@matrix.org>
Date: Tue, 23 Sep 2014 17:16:13 +0100
Subject: [PATCH] Add support for TURN servers as per the TURN REST API
 (http://tools.ietf.org/html/draft-uberti-behave-turn-rest-00)

---
 synapse/config/homeserver.py |  3 +-
 synapse/config/voip.py       | 41 +++++++++++++++++++++++++
 synapse/rest/__init__.py     |  3 +-
 synapse/rest/voip.py         | 59 ++++++++++++++++++++++++++++++++++++
 4 files changed, 104 insertions(+), 2 deletions(-)
 create mode 100644 synapse/config/voip.py
 create mode 100644 synapse/rest/voip.py

diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index 4b810a230..5a11fd6c7 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -21,11 +21,12 @@ from .ratelimiting import RatelimitConfig
 from .repository import ContentRepositoryConfig
 from .captcha import CaptchaConfig
 from .email import EmailConfig
+from .voip import VoipConfig
 
 
 class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
                        RatelimitConfig, ContentRepositoryConfig, CaptchaConfig,
-                       EmailConfig):
+                       EmailConfig, VoipConfig):
     pass
 
 
diff --git a/synapse/config/voip.py b/synapse/config/voip.py
new file mode 100644
index 000000000..a47e81037
--- /dev/null
+++ b/synapse/config/voip.py
@@ -0,0 +1,41 @@
+# Copyright 2014 OpenMarket 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 ._base import Config
+
+
+class VoipConfig(Config):
+
+    def __init__(self, args):
+        super(VoipConfig, self).__init__(args)
+        self.turn_uri = args.turn_uri
+        self.turn_shared_secret = args.turn_shared_secret
+        self.turn_user_lifetime = args.turn_user_lifetime
+
+    @classmethod
+    def add_arguments(cls, parser):
+        super(VoipConfig, cls).add_arguments(parser)
+        group = parser.add_argument_group("voip")
+        group.add_argument(
+            "--turn-uri", type=str, default=None,
+            help="The public URI of the TURN server to give to clients"
+        )
+        group.add_argument(
+            "--turn-shared-secret", type=str, default=None,
+            help="The shared secret used to compute passwords for the TURN server"
+        )
+        group.add_argument(
+            "--turn-user-lifetime", type=int, default=(1000 * 60 * 60),
+            help="How long generated TURN credentials last, in ms"
+        )
diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index ed785cfbd..3b9aa5973 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -15,7 +15,7 @@
 
 
 from . import (
-    room, events, register, login, profile, presence, initial_sync, directory
+    room, events, register, login, profile, presence, initial_sync, directory, voip
 )
 
 
@@ -42,3 +42,4 @@ class RestServletFactory(object):
         presence.register_servlets(hs, client_resource)
         initial_sync.register_servlets(hs, client_resource)
         directory.register_servlets(hs, client_resource)
+        voip.register_servlets(hs, client_resource)
diff --git a/synapse/rest/voip.py b/synapse/rest/voip.py
new file mode 100644
index 000000000..cba9b27e3
--- /dev/null
+++ b/synapse/rest/voip.py
@@ -0,0 +1,59 @@
+# -*- coding: utf-8 -*-
+# Copyright 2014 OpenMarket 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 twisted.internet import defer
+
+from base import RestServlet, client_path_pattern
+
+from syutil.base64util import encode_base64
+
+import hmac
+import hashlib
+
+
+class VoipRestServlet(RestServlet):
+    PATTERN = client_path_pattern("/voip/turnuris$")
+
+    @defer.inlineCallbacks
+    def on_GET(self, request):
+        auth_user = yield self.auth.get_user_by_req(request)
+
+        turnUri = self.hs.config.voip.turn_uri
+        turnSecret = self.hs.config.voip.turn_shared_secret
+        userLifetime = self.hs.config.voip.turn_user_lifetime
+        if not turnUri or not turnSecret or not userLifetime:
+            defer.returnValue( (200, {"uris": []}) )
+
+        expiry = self.hs.get_clock().time_msec() + userLifetime
+        username = "%d:%s" % (expiry, auth_user.to_string())
+         
+        mac = hmac.new(turnSecret, msg=username, digestmod=hashlib.sha1)
+        password = encode_base64(mac.digest())
+
+        defer.returnValue( (200, {
+            'username': username,
+            'password': password,
+            'ttl': userLifetime / 1000,
+            'uris': [
+                turnUri,
+            ]
+        }) )
+
+    def on_OPTIONS(self, request):
+        return (200, {})
+
+
+def register_servlets(hs, http_server):
+    VoipRestServlet(hs).register(http_server)