Initial hack at the 3PN protocols metadata lookup API

synapse/appservice/__init__.py

@@ -88,6 +88,8 @@ class ApplicationService(object):
         self.sender = sender
         self.namespaces = self._check_namespaces(namespaces)
         self.id = id
+
+        # .protocols is a publicly visible field
         if protocols:
             self.protocols = set(protocols)
         else:

synapse/handlers/appservice.py

@@ -175,6 +175,14 @@ class ApplicationServicesHandler(object):
 
         defer.returnValue(ret)
 
+    @defer.inlineCallbacks
+    def get_3pe_protocols(self):
+        services = yield self.store.get_app_services()
+        protocols = set()
+        for s in services:
+            protocols.update(s.protocols)
+        defer.returnValue(protocols)
+
     @defer.inlineCallbacks
     def _get_services_for_event(self, event):
         """Retrieve a list of application services interested in this event.

synapse/rest/client/v2_alpha/thirdparty.py

@@ -25,6 +25,39 @@ from ._base import client_v2_patterns
 logger = logging.getLogger(__name__)
 
 
+class ThirdPartyProtocolsServlet(RestServlet):
+    PATTERNS = client_v2_patterns("/thirdparty/protocols", releases=())
+
+    META = {
+        # TODO(paul): Declare kinds of metadata in here
+    }
+
+    def __init__(self, hs):
+        super(ThirdPartyProtocolsServlet, self).__init__()
+
+        self.auth = hs.get_auth()
+        self.appservice_handler = hs.get_application_service_handler()
+
+    @defer.inlineCallbacks
+    def on_GET(self, request):
+        yield self.auth.get_user_by_req(request)
+
+        protocols = yield self.appservice_handler.get_3pe_protocols()
+
+        result = {}
+        # TODO(paul): Eventually this kind of metadata wants to come from the
+        #   ASes themselves
+        for protocol in protocols:
+            if protocol in self.META:
+                result[protocol] = self.META[protocol]
+            else:
+                # We don't know any metadata for it, but we'd best at least
+                # still declare that we know it exists
+                result[protocol] = {}
+
+        defer.returnValue((200, result))
+
+
 class ThirdPartyUserServlet(RestServlet):
     PATTERNS = client_v2_patterns("/thirdparty/user(/(?P<protocol>[^/]+))?$",
                                   releases=())
@@ -74,5 +107,6 @@ class ThirdPartyLocationServlet(RestServlet):
 
 
 def register_servlets(hs, http_server):
+    ThirdPartyProtocolsServlet(hs).register(http_server)
     ThirdPartyUserServlet(hs).register(http_server)
     ThirdPartyLocationServlet(hs).register(http_server)