platform/netlink: move generic code in _netlink_recv_handle()

This also applies to genl messages. Move the code.

src/libnm-platform/nm-linux-platform.c

@@ -4140,8 +4140,7 @@ nmp_object_new_from_nl(NMPlatform               *platform,
 {
     const struct nlmsghdr *msghdr;
 
-    if (msg->nm_protocol != NETLINK_ROUTE)
-        return NULL;
+    nm_assert(msg->nm_protocol == NETLINK_ROUTE);
 
     msghdr = msg->nm_nlh;
 
@@ -9317,9 +9316,6 @@ continue_reading:
             /* FIXME: implement */
         }
 
-        switch (netlink_protocol) {
-        case NETLINK_ROUTE:
-        {
         seq_result = WAIT_FOR_NL_RESPONSE_RESULT_RESPONSE_UNKNOWN;
 
         if (msg.nm_nlh->nlmsg_type == NLMSG_DONE) {
@@ -9376,8 +9372,7 @@ continue_reading:
                 }
 
                 /* Error message reported back from kernel. */
-                    _LOGD(
-                        "netlink: recvmsg: error message from kernel: %s (%d)%s%s%s for request %d",
+                _LOGD("netlink: recvmsg: error message from kernel: %s (%d)%s%s%s for request %d",
                       nm_strerror_native(errsv),
                       errsv,
                       NM_PRINT_FMT_QUOTED(extack_msg, " \"", extack_msg, "\"", ""),
@@ -9388,6 +9383,11 @@ continue_reading:
         } else
             process_valid_msg = TRUE;
 
+        switch (netlink_protocol) {
+        default:
+            nm_assert_not_reached();
+            /* fall-through */
+        case NETLINK_ROUTE:
             /* check whether the seq number is different from before, and
              * whether the previous number (@nlh_seq_last_seen) is a pending
              * refresh-all request. In that case, the pending request is thereby
@@ -9410,9 +9410,6 @@ continue_reading:
             event_seq_check(platform, seq_number, seq_result, extack_msg);
             break;
         }
-        default:
-            nm_assert_not_reached();
-        }
 
         if (abort_parsing)
             goto stop;
@@ -9425,6 +9422,7 @@ continue_reading:
         /* Multipart message not yet complete, continue reading */
         goto continue_reading;
     }
+
 stop:
     if (!handle_events) {
         /* when we don't handle events, we want to drain all messages from the socket