Merge pull request #2623 from matrix-org/rav/callbacks_for_auth_provi…

…ders

Allow password_auth_providers to return a callback

docs/password_auth_providers.rst

@@ -70,6 +70,11 @@ Password auth provider classes may optionally provide the following methods.
     the canonical ``@localpart:domain`` user id if authentication is successful,
     and ``None`` if not.
 
+    Alternatively, the ``Deferred`` can resolve to a ``(str, func)`` tuple, in
+    which case the second field is a callback which will be called with the
+    result from the ``/login`` call (including ``access_token``, ``device_id``,
+    etc.)
+
 ``someprovider.check_password``\(*user_id*, *password*)
 
     This method provides a simpler interface than ``get_supported_login_types``

synapse/handlers/auth.py

@@ -270,17 +270,19 @@ def get_session_data(self, session_id, key, default=None):
         sess = self._get_session_info(session_id)
         return sess.setdefault('serverdict', {}).get(key, default)
 
+    @defer.inlineCallbacks
     def _check_password_auth(self, authdict, _):
         if "user" not in authdict or "password" not in authdict:
             raise LoginError(400, "", Codes.MISSING_PARAM)
 
         user_id = authdict["user"]
         password = authdict["password"]
 
-        return self.validate_login(user_id, {
+        (canonical_id, callback) = yield self.validate_login(user_id, {
             "type": LoginType.PASSWORD,
             "password": password,
         })
+        defer.returnValue(canonical_id)
 
     @defer.inlineCallbacks
     def _check_recaptcha(self, authdict, clientip):
@@ -517,7 +519,8 @@ def validate_login(self, username, login_submission):
             login_submission (dict): the whole of the login submission
                 (including 'type' and other relevant fields)
         Returns:
-            Deferred[str]: canonical user id
+            Deferred[str, func]: canonical user id, and optional callback
+                to be called once the access token and device id are issued
         Raises:
             StoreError if there was a problem accessing the database
             SynapseError if there was a problem with the request
@@ -581,11 +584,13 @@ def validate_login(self, username, login_submission):
                     ),
                 )
 
-            returned_user_id = yield provider.check_auth(
+            result = yield provider.check_auth(
                 username, login_type, login_dict,
             )
-            if returned_user_id:
-                defer.returnValue(returned_user_id)
+            if result:
+                if isinstance(result, str):
+                    result = (result, None)
+                defer.returnValue(result)
 
         if login_type == LoginType.PASSWORD:
             known_login_type = True
@@ -595,7 +600,7 @@ def validate_login(self, username, login_submission):
             )
 
             if canonical_user_id:
-                defer.returnValue(canonical_user_id)
+                defer.returnValue((canonical_user_id, None))
 
         if not known_login_type:
             raise SynapseError(400, "Unknown login type %s" % login_type)

synapse/rest/client/v1/login.py

@@ -219,7 +219,7 @@ def _do_other_login(self, login_submission):
             raise SynapseError(400, "User identifier is missing 'user' key")
 
         auth_handler = self.auth_handler
-        canonical_user_id = yield auth_handler.validate_login(
+        canonical_user_id, callback = yield auth_handler.validate_login(
             identifier["user"],
             login_submission,
         )
@@ -238,6 +238,9 @@ def _do_other_login(self, login_submission):
             "device_id": device_id,
         }
 
+        if callback is not None:
+            yield callback(result)
+
         defer.returnValue((200, result))
 
     @defer.inlineCallbacks