Printf debugging for MSISDN validation (#11882)

This makes some attempt to keep CI happy too, but it probably ought not to.

synapse/handlers/message.py

@@ -277,8 +277,8 @@ class MessageHandler:
         # If this is an AS, double check that they are allowed to see the members.
         # This can either be because the AS user is in the room or because there
         # is a user in the room that the AS is "interested in"
-        if False and requester.app_service and user_id not in users_with_profile:
-            for uid in users_with_profile:
+        if False and requester.app_service and user_id not in users_with_profile:  # type: ignore[unreachable]
+            for uid in users_with_profile:  # type: ignore[unreachable]
                 if requester.app_service.is_interested_in_user(uid):
                     break
             else:

synapse/rest/client/account.py

@@ -467,6 +467,7 @@ class MsisdnThreepidRequestTokenRestServlet(RestServlet):
         next_link = body.get("next_link")  # Optional param
 
         msisdn = phone_number_to_msisdn(country, phone_number)
+        logger.info("Request #%s to verify ownership of %s", send_attempt, msisdn)
 
         if not check_3pid_allowed(self.hs, "msisdn", msisdn):
             raise SynapseError(
@@ -494,6 +495,7 @@ class MsisdnThreepidRequestTokenRestServlet(RestServlet):
                 await self.hs.get_clock().sleep(random.randint(1, 10) / 10)
                 return 200, {"sid": random_string(16)}
 
+            logger.info("MSISDN %s is already in use by %s", msisdn, existing_user_id)
             raise SynapseError(400, "MSISDN is already in use", Codes.THREEPID_IN_USE)
 
         if not self.hs.config.registration.account_threepid_delegate_msisdn:
@@ -518,6 +520,7 @@ class MsisdnThreepidRequestTokenRestServlet(RestServlet):
         threepid_send_requests.labels(type="msisdn", reason="add_threepid").observe(
             send_attempt
         )
+        logger.info("MSISDN %s: got response from identity server: %s", msisdn, ret)
 
         return 200, ret