From 14417fb0e615596cf3dd80b058c65f2c806cab0f Mon Sep 17 00:00:00 2001
From: Christian Huitema <huitema@huitema.net>
Date: Sat, 16 Mar 2024 13:27:24 -0700
Subject: [PATCH] Send abandon in response to abandon.

---
 picoquic/frames.c            | 14 ++++++++++++--
 picoquic/picoquic_internal.h |  1 +
 picoquic/quicctx.c           |  4 ++--
 3 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/picoquic/frames.c b/picoquic/frames.c
index ddde42d1f..6b5a0aa8c 100644
--- a/picoquic/frames.c
+++ b/picoquic/frames.c
@@ -5345,11 +5345,21 @@ const uint8_t* picoquic_decode_path_abandon_frame(const uint8_t* bytes, const ui
         int path_number = (cnx->is_unique_path_id_enabled)?
             picoquic_find_path_by_unique_id(cnx, path_id):
             picoquic_find_path_by_cnxid_id(cnx, 1, path_id);
-        if (path_number < 0 || cnx->path[path_number]->path_is_demoted) {
+        if (path_number < 0) {
             /* Invalid path ID. Just ignore this frame. Add line in log for debug */
-            picoquic_log_app_message(cnx, "Ignore abandon path with invalid ID: %" PRIu64 ",%" PRIu64,
+            picoquic_log_app_message(cnx, "Ignore abandon path with invalid ID: %" PRIu64,
                 path_id);
         }
+        else if (cnx->path[path_number]->path_is_demoted) {
+            if (!cnx->path[path_number]->path_abandon_received) {
+                cnx->path[path_number]->path_abandon_received = 1;
+            }
+            else {
+                /* Already abandoned... */
+                picoquic_log_app_message(cnx, "Ignore redundant abandon path with ID: %" PRIu64,
+                    path_id);
+            }
+        }
         else {
             cnx->path[path_number]->path_abandon_received = 1;
             picoquic_demote_path(cnx, path_number, current_time, 0, NULL);
diff --git a/picoquic/picoquic_internal.h b/picoquic/picoquic_internal.h
index 59f0cb17e..c9b2c7252 100644
--- a/picoquic/picoquic_internal.h
+++ b/picoquic/picoquic_internal.h
@@ -1061,6 +1061,7 @@ typedef struct st_picoquic_path_t {
     unsigned int path_is_standby : 1;
     unsigned int path_is_demoted : 1;
     unsigned int path_abandon_received : 1;
+    unsigned int path_abandon_sent : 1;
     unsigned int current_spin : 1;
     unsigned int last_bw_estimate_path_limited : 1;
     unsigned int path_cid_rotated : 1;
diff --git a/picoquic/quicctx.c b/picoquic/quicctx.c
index 75a075593..891ee8feb 100644
--- a/picoquic/quicctx.c
+++ b/picoquic/quicctx.c
@@ -1819,7 +1819,7 @@ void picoquic_demote_path(picoquic_cnx_t* cnx, int path_index, uint64_t current_
         /* if in multipath, call "retransmit on path demoted" */
         if (cnx->is_multipath_enabled || cnx->is_simple_multipath_enabled ||
             cnx->is_unique_path_id_enabled) {
-            if (!cnx->path[path_index]->path_abandon_received) {
+            if (!cnx->path[path_index]->path_abandon_sent) {
                 uint8_t buffer[512];
                 uint8_t* end_bytes;
                 int more_data = 0;
@@ -1835,7 +1835,7 @@ void picoquic_demote_path(picoquic_cnx_t* cnx, int path_index, uint64_t current_
                         cnx->path[path_index]->unique_path_id);
                 }
             }
-            picoquic_retransmit_demoted_path(cnx, cnx->path[path_index], current_time);
+            /* let's not retransmit immediately -- wait for normal processing instead */
         }
     }
 }