# HG changeset patch
# User Sergey Kandaurov <pluknet@nginx.com>
# Date 1683646960 -14400
# Node ID a9fef6ca45a86deeecc176c10316a575f7ca4dc3
# Parent  c6db94ec38419b1590f7ef6b855306635219e9e9
QUIC: lower bound path validation PTO.

According to RFC 9000, 8.2.4. Failed Path Validation,
the following value is recommended as a validation timeout:

  A value of three times the larger of the current PTO
  or the PTO for the new path (using kInitialRtt, as
  defined in [QUIC-RECOVERY]) is RECOMMENDED.

The change adds PTO of the new path to the equation as the lower bound.

diff --git a/src/event/quic/ngx_event_quic_migration.c b/src/event/quic/ngx_event_quic_migration.c
--- a/src/event/quic/ngx_event_quic_migration.c
+++ b/src/event/quic/ngx_event_quic_migration.c
@@ -511,7 +511,7 @@ ngx_quic_validate_path(ngx_connection_t 
     }
 
     ctx = ngx_quic_get_send_ctx(qc, ssl_encryption_application);
-    pto = ngx_quic_pto(c, ctx);
+    pto = ngx_max(ngx_quic_pto(c, ctx), 1000);
 
     path->expires = ngx_current_msec + pto;
 
@@ -605,7 +605,7 @@ ngx_quic_path_validation_handler(ngx_eve
         }
 
         if (++path->tries < NGX_QUIC_PATH_RETRIES) {
-            pto = ngx_quic_pto(c, ctx) << path->tries;
+            pto = ngx_max(ngx_quic_pto(c, ctx), 1000) << path->tries;
 
             path->expires = ngx_current_msec + pto;