Threepid validity checks on msisdns should not be dependent on 'threepid_behaviour_email'. (#6104)

Fixes #6103

changelog.d/6104.bugfix

@@ -0,0 +1 @@
+Threepid validity checks on msisdns should not be dependent on 'threepid_behaviour_email'.

synapse/handlers/ui_auth/checkers.py

@@ -148,18 +148,24 @@ class _BaseThreepidAuthChecker:
         identity_handler = self.hs.get_handlers().identity_handler
 
         logger.info("Getting validated threepid. threepidcreds: %r", (threepid_creds,))
-        if self.hs.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
-            if medium == "email":
-                threepid = yield identity_handler.threepid_from_creds(
-                    self.hs.config.account_threepid_delegate_email, threepid_creds
+
+        # msisdns are currently always ThreepidBehaviour.REMOTE
+        if medium == "msisdn":
+            if not self.hs.config.account_threepid_delegate_msisdn:
+                raise SynapseError(
+                    400, "Phone number verification is not enabled on this homeserver"
                 )
-            elif medium == "msisdn":
             threepid = yield identity_handler.threepid_from_creds(
                 self.hs.config.account_threepid_delegate_msisdn, threepid_creds
             )
-            else:
-                raise SynapseError(400, "Unrecognized threepid medium: %s" % (medium,))
+        elif medium == "email":
+            if self.hs.config.threepid_behaviour_email == ThreepidBehaviour.REMOTE:
+                assert self.hs.config.account_threepid_delegate_email
+                threepid = yield identity_handler.threepid_from_creds(
+                    self.hs.config.account_threepid_delegate_email, threepid_creds
+                )
             elif self.hs.config.threepid_behaviour_email == ThreepidBehaviour.LOCAL:
+                threepid = None
                 row = yield self.store.get_threepid_validation_session(
                     medium,
                     threepid_creds["client_secret"],
@@ -167,23 +173,22 @@ class _BaseThreepidAuthChecker:
                     validated=True,
                 )
 
-            threepid = (
-                {
+                if row:
+                    threepid = {
                         "medium": row["medium"],
                         "address": row["address"],
                         "validated_at": row["validated_at"],
                     }
-                if row
-                else None
-            )
 
-            if row:
                     # Valid threepid returned, delete from the db
                     yield self.store.delete_threepid_session(threepid_creds["sid"])
             else:
                 raise SynapseError(
-                400, "Password resets are not enabled on this homeserver"
+                    400, "Email address verification is not enabled on this homeserver"
                 )
+        else:
+            # this can't happen!
+            raise AssertionError("Unrecognized threepid medium: %s" % (medium,))
 
         if not threepid:
             raise LoginError(401, "", errcode=Codes.UNAUTHORIZED)