[+] add least_available_cid_count for client option

demo/demo_client.c

@@ -174,6 +174,8 @@ typedef struct xqc_demo_cli_quic_config_s {
     uint8_t send_path_standby;
     xqc_msec_t path_status_timer_threshold;
 
+    uint64_t least_available_cid_count;
+
 } xqc_demo_cli_quic_config_t;
 
 

demo/demo_server.c

@@ -99,6 +99,7 @@ typedef struct xqc_demo_svr_quic_config_s {
     uint32_t reinjection;
 
     uint64_t keyupdate_pkt_threshold;
+    uint64_t least_available_cid_count;
 } xqc_demo_svr_quic_config_t;
 
 
@@ -1220,13 +1221,14 @@ xqc_demo_svr_init_args(xqc_demo_svr_args_t *args)
     strncpy(args->env_cfg.cert_pem_path, CERT_PEM_PATH, PATH_LEN - 1);
 
     args->quic_cfg.keyupdate_pkt_threshold = UINT64_MAX;
+    args->quic_cfg.least_available_cid_count = 1;
 }
 
 void
 xqc_demo_svr_parse_args(int argc, char *argv[], xqc_demo_svr_args_t *args)
 {
     int ch = 0;
-    while ((ch = getopt(argc, argv, "p:c:CD:l:L:6k:rdMPs:R:u:")) != -1) {
+    while ((ch = getopt(argc, argv, "p:c:CD:l:L:6k:rdMPs:R:u:a:")) != -1) {
         switch (ch) {
         /* listen port */
         case 'p':
@@ -1331,6 +1333,11 @@ xqc_demo_svr_parse_args(int argc, char *argv[], xqc_demo_svr_args_t *args)
             args->quic_cfg.keyupdate_pkt_threshold = atoi(optarg);
             break;
 
+        case 'a': /* key update packet threshold */
+            printf("least Available cid counts: %s\n", optarg);
+            args->quic_cfg.least_available_cid_count = atoi(optarg);
+            break;
+
         default:
             printf("other option :%c\n", ch);
             xqc_demo_svr_usage(argc, argv);
@@ -1445,6 +1452,7 @@ xqc_demo_svr_init_conn_settings(xqc_demo_svr_args_t *args)
         .mp_enable_reinjection = args->quic_cfg.reinjection,
         .standby_path_probe_timeout = 1000,
         .keyupdate_pkt_threshold = args->quic_cfg.keyupdate_pkt_threshold,
+        .least_available_cid_count = args->quic_cfg.least_available_cid_count,
     };
 
     xqc_server_set_conn_settings(&conn_settings);

include/xquic/xquic.h

@@ -1171,7 +1171,7 @@ typedef struct xqc_conn_settings_s {
      */
     uint64_t                    enable_multipath;
     xqc_multipath_version_t     multipath_version;
-
+    uint64_t                    least_available_cid_count;
 
     /*
      * reinjection option:

src/transport/xqc_conn.c

@@ -4108,6 +4108,9 @@ xqc_conn_try_add_new_conn_id(xqc_connection_t *conn, uint64_t retire_prior_to)
     uint64_t unused_limit = 1;
 #else
     uint64_t unused_limit = conn->enable_multipath ? 2 : 1;
+    if (conn->enable_multipath) {
+        unused_limit = xqc_max(unused_limit, conn->conn_settings.least_available_cid_count);
+    }
 #endif
     if (xqc_conn_is_handshake_confirmed(conn)) {
         while (active_cid_cnt < conn->remote_settings.active_connection_id_limit