From d9b2c378376468a2aa2a75b24b2c3b9a3f82dc48 Mon Sep 17 00:00:00 2001
From: msvoelker <timo.voelker@fh-muenster.de>
Date: Tue, 26 Jul 2022 17:47:31 +0200
Subject: [PATCH] set socket option IPV6_MTU_DISCOVER=IP_PMTUDISC_PROBE for
 linux (#399)

---
 bin/CMakeLists.txt   |  6 ++++++
 bin/test_common.c    | 14 ++++++++++++++
 bin/test_config.h.in |  2 +-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/bin/CMakeLists.txt b/bin/CMakeLists.txt
index 0872f11..5afd506 100644
--- a/bin/CMakeLists.txt
+++ b/bin/CMakeLists.txt
@@ -85,6 +85,12 @@ CHECK_SYMBOL_EXISTS(
     HAVE_IP_MTU_DISCOVER
 )
 
+CHECK_SYMBOL_EXISTS(
+    IPV6_MTU_DISCOVER
+    "netinet/in.h"
+    HAVE_IPV6_MTU_DISCOVER
+)
+
 CHECK_SYMBOL_EXISTS(
     IP_DONTFRAG
     "netinet/in.h"
diff --git a/bin/test_common.c b/bin/test_common.c
index 685947d..b15df86 100644
--- a/bin/test_common.c
+++ b/bin/test_common.c
@@ -964,6 +964,13 @@ sport_init_server (struct service_port *sport, struct lsquic_engine *engine,
                 return -1;
             }
         }
+#if __linux__
+        else if (AF_INET6 == sa_local->sa_family)
+        {
+            int on = IP_PMTUDISC_PROBE;
+            s = setsockopt(sockfd, IPPROTO_IPV6, IPV6_MTU_DISCOVER, &on, sizeof(on));
+        }
+#endif
     }
 #endif
 
@@ -1156,6 +1163,13 @@ sport_init_client (struct service_port *sport, struct lsquic_engine *engine,
                 return -1;
             }
         }
+#if __linux__
+        else if (AF_INET6 == sa_local->sa_family)
+        {
+            int on = IP_PMTUDISC_PROBE;
+            s = setsockopt(sockfd, IPPROTO_IPV6, IPV6_MTU_DISCOVER, &on, sizeof(on));
+        }
+#endif
     }
 #endif
 
diff --git a/bin/test_config.h.in b/bin/test_config.h.in
index f7ea4a3..1c2ffba 100644
--- a/bin/test_config.h.in
+++ b/bin/test_config.h.in
@@ -9,7 +9,7 @@
 #cmakedefine HAVE_REGEX 1
 #cmakedefine HAVE_PREADV 1
 
-#define LSQUIC_DONTFRAG_SUPPORTED (HAVE_IP_DONTFRAG || HAVE_IP_MTU_DISCOVER)
+#define LSQUIC_DONTFRAG_SUPPORTED (HAVE_IP_DONTFRAG || HAVE_IP_MTU_DISCOVER || HAVE_IPV6_MTU_DISCOVER)
 
 /* TODO: presumably it's the same on FreeBSD, test it.
  * See https://github.com/quicwg/base-drafts/wiki/ECN-in-QUIC