Support MSC2033: Device ID on whoami (#9918)

* Fix no-access-token bug in deactivation tests
* Support MSC2033: Device ID on whoami
* Test for appservices too

MSC: https://github.com/matrix-org/matrix-doc/pull/2033

The MSC has passed FCP, which means stable endpoints can be used.

3 files changed, 51 insertions, 2 deletions

diff --git a/changelog.d/9918.feature b/changelog.d/9918.feature
new file mode 100644
index 0000000000..98f0a50893
--- /dev/null
+++ b/changelog.d/9918.feature
@@ -0,0 +1 @@
+Add support for [MSC2033](https://github.com/matrix-org/matrix-doc/pull/2033): `device_id` on `/account/whoami`.
\ No newline at end of file
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 085561d3e9..fb5ad2906e 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -884,7 +884,14 @@ class WhoamiRestServlet(RestServlet):
     async def on_GET(self, request):
         requester = await self.auth.get_user_by_req(request)
 
-        return 200, {"user_id": requester.user.to_string()}
+        response = {"user_id": requester.user.to_string()}
+
+        # Appservices and similar accounts do not have device IDs
+        # that we can report on, so exclude them for compliance.
+        if requester.device_id is not None:
+            response["device_id"] = requester.device_id
+
+        return 200, response
 
 
 def register_servlets(hs, http_server):
diff --git a/tests/rest/client/v2_alpha/test_account.py b/tests/rest/client/v2_alpha/test_account.py
index 4ef19145d1..317a2287e3 100644
--- a/tests/rest/client/v2_alpha/test_account.py
+++ b/tests/rest/client/v2_alpha/test_account.py
@@ -24,6 +24,7 @@ import pkg_resources
 import synapse.rest.admin
 from synapse.api.constants import LoginType, Membership
 from synapse.api.errors import Codes, HttpResponseException
+from synapse.appservice import ApplicationService
 from synapse.rest.client.v1 import login, room
 from synapse.rest.client.v2_alpha import account, register
 from synapse.rest.synapse.client.password_reset import PasswordResetSubmitTokenResource
@@ -397,7 +398,7 @@ class DeactivateTestCase(unittest.HomeserverTestCase):
         self.assertTrue(self.get_success(store.get_user_deactivated_status(user_id)))
 
         # Check that this access token has been invalidated.
-        channel = self.make_request("GET", "account/whoami")
+        channel = self.make_request("GET", "account/whoami", access_token=tok)
         self.assertEqual(channel.code, 401)
 
     def test_pending_invites(self):
@@ -458,6 +459,46 @@ class DeactivateTestCase(unittest.HomeserverTestCase):
         self.assertEqual(channel.code, 200)
 
 
+class WhoamiTestCase(unittest.HomeserverTestCase):
+
+    servlets = [
+        synapse.rest.admin.register_servlets_for_client_rest_resource,
+        login.register_servlets,
+        account.register_servlets,
+        register.register_servlets,
+    ]
+
+    def test_GET_whoami(self):
+        device_id = "wouldgohere"
+        user_id = self.register_user("kermit", "test")
+        tok = self.login("kermit", "test", device_id=device_id)
+
+        whoami = self.whoami(tok)
+        self.assertEqual(whoami, {"user_id": user_id, "device_id": device_id})
+
+    def test_GET_whoami_appservices(self):
+        user_id = "@as:test"
+        as_token = "i_am_an_app_service"
+
+        appservice = ApplicationService(
+            as_token,
+            self.hs.config.server_name,
+            id="1234",
+            namespaces={"users": [{"regex": user_id, "exclusive": True}]},
+            sender=user_id,
+        )
+        self.hs.get_datastore().services_cache.append(appservice)
+
+        whoami = self.whoami(as_token)
+        self.assertEqual(whoami, {"user_id": user_id})
+        self.assertFalse(hasattr(whoami, "device_id"))
+
+    def whoami(self, tok):
+        channel = self.make_request("GET", "account/whoami", {}, access_token=tok)
+        self.assertEqual(channel.code, 200)
+        return channel.json_body
+
+
 class ThreepidEmailRestTestCase(unittest.HomeserverTestCase):
 
     servlets = [