restore state whenever handling of NCID fails

h2o · Dec 23, 2024 · c0451b0 · c0451b0
1 parent cf2e0a5
commit c0451b0
Showing 1 changed file with 4 additions and 8 deletions.
diff --git a/lib/remote_cid.c b/lib/remote_cid.c
@@ -135,15 +135,11 @@ int quicly_remote_cid_register(quicly_remote_cid_set_t *set, uint64_t sequence,
     assert(sequence >= retire_prior_to);
 
     /* First, handle retire_prior_to. This order is important as it is possible to receive a NEW_CONNECTION_ID frame such that it
-     * retires active_connection_id_limit CIDs and then installs one new CID. */
-    if ((ret = unregister_prior_to(set, retire_prior_to)) != 0)
-        return ret;
-
-    /* Then, register given value. If an error occurs, restore the backup and send the error. */
-    if ((ret = do_register(set, sequence, cid, cid_len, srt)) != 0) {
+     * retires active_connection_id_limit CIDs and then installs one new CID. Then, the new CID is registered. If either of the two
+     * fails, the state is restored to the original so that we can send an error to the peer. */
+    if ((ret = unregister_prior_to(set, retire_prior_to)) != 0 ||
+        (ret = do_register(set, sequence, cid, cid_len, srt)) != 0)
         *set = backup;
-        return ret;
-    }
 
     return ret;
 }