improve handling of CID retirement

CMakeLists.txt

@@ -59,7 +59,6 @@ SET(QUICLY_LIBRARY_FILES
     lib/rate.c
     lib/recvstate.c
     lib/remote_cid.c
-    lib/retire_cid.c
     lib/sendstate.c
     lib/sentmap.c
     lib/streambuf.c
@@ -77,7 +76,6 @@ SET(UNITTEST_SOURCE_FILES
     t/ranges.c
     t/rate.c
     t/remote_cid.c
-    t/retire_cid.c
     t/sentmap.c
     t/simple.c
     t/stream-concurrency.c

include/quicly/constants.h

@@ -108,7 +108,7 @@ typedef int64_t quicly_error_t;
 #define QUICLY_TRANSPORT_ERROR_AEAD_LIMIT_REACHED QUICLY_ERROR_FROM_TRANSPORT_ERROR_CODE(0xf)
 #define QUICLY_TRANSPORT_ERROR_CRYPTO(tls_alert) QUICLY_ERROR_FROM_TRANSPORT_ERROR_CODE(0x100 + (tls_alert))
 
-/* internal error codes, used purely for signaling status to the application */
+/* local error codes, used for signaling status between quicly and the application */
 #define QUICLY_ERROR_PACKET_IGNORED 0xff01
 #define QUICLY_ERROR_SENDBUF_FULL 0xff02    /* internal use only; the error code is never exposed to the application */
 #define QUICLY_ERROR_FREE_CONNECTION 0xff03 /* returned by quicly_send when the connection is freeable */

include/quicly/remote_cid.h

@@ -84,6 +84,13 @@ typedef struct st_quicly_remote_cid_set_t {
      * we expect to receive CIDs with sequence number smaller than or equal to this number
      */
     uint64_t _largest_sequence_expected;
+    /**
+     * queue containing CID sequence numbers that should be sent using RETIRE_CONNECTION_ID frames
+     */
+    struct {
+        uint64_t cids[QUICLY_LOCAL_ACTIVE_CONNECTION_ID_LIMIT * 2];
+        size_t count;
+    } retired;
 } quicly_remote_cid_set_t;
 
 /**
@@ -93,17 +100,24 @@ typedef struct st_quicly_remote_cid_set_t {
  */
 void quicly_remote_cid_init_set(quicly_remote_cid_set_t *set, ptls_iovec_t *initial_cid, void (*random_bytes)(void *, size_t));
 /**
- * registers received connection ID
- * returns 0 if successful (registered or ignored because of duplication/stale information), transport error code otherwise
+ * Registers received connection ID at the same time pushing CIDs onto the retired queue, if any. Returns 0 if successful (CID set
+ * is either updated or given information is ignored due to being state), or a transport error code if an error occurs.
  */
 quicly_error_t quicly_remote_cid_register(quicly_remote_cid_set_t *set, uint64_t sequence, const uint8_t *cid, size_t cid_len,
-                                          const uint8_t srt[QUICLY_STATELESS_RESET_TOKEN_LEN], uint64_t retire_prior_to,
-                                          uint64_t unregistered_seqs[QUICLY_LOCAL_ACTIVE_CONNECTION_ID_LIMIT],
-                                          size_t *num_unregistered_seqs);
+                                          const uint8_t srt[QUICLY_STATELESS_RESET_TOKEN_LEN], uint64_t retire_prior_to);
+/**
+ * Unregisters specified CID from the store, pushing the unregistered CID onto the retired queue. The former always succeeds, while
+ * the latter might fail due to state exhaustion, in which case an error is returned.
+ */
+int quicly_remote_cid_unregister(quicly_remote_cid_set_t *set, uint64_t sequence);
+/**
+ * pushes a CID sequence number to the retired queue
+ */
+int quicly_remote_cid_push_retired(quicly_remote_cid_set_t *set, uint64_t sequence);
 /**
- * unregisters specified CID from the store
+ * removed the first `count` sequence numbers from the retired queue
  */
-void quicly_remote_cid_unregister(quicly_remote_cid_set_t *set, uint64_t sequence);
+void quicly_remote_cid_shift_retired(quicly_remote_cid_set_t *set, size_t count);
 
 #ifdef __cplusplus
 }