- Fix to stop IPv6 PMTU discovery.

diff --git a/doc/Changelog b/doc/Changelog
index c816b2e9dc5049d2701fc77e499c150bb0f1d8d3..66e6f9a481bbfbff4c5899e9f2e66f0d362d07bf 100644 (file)
--- a/doc/Changelog
+++ b/doc/Changelog
@@ -1,5 +1,6 @@
 1 April 2021: Wouter
        - Merge #460 from orbea: build: Link with the libtool archive.
+       - Fix to stop IPv6 PMTU discovery.
 
 31 March 2021: George
        - Clean makedist.sh.

diff --git a/services/listen_dnsport.c b/services/listen_dnsport.c
index 81a7856eb042ac7b944d8c8e15530e1fd6ecbe2a..ca40fac5cc67cf40189ed127ed7f0aa74fef1097 100644 (file)
--- a/services/listen_dnsport.c
+++ b/services/listen_dnsport.c
@@ -452,6 +452,10 @@ create_udp_sock(int family, int socktype, struct sockaddr* addr,
        if(err != NULL)
                log_warn("error setting IP DiffServ codepoint %d on UDP socket: %s", dscp, err);
        if(family == AF_INET6) {
+# if defined(IPV6_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
+               int omit6_set = 0;
+               int action;
+# endif
 # if defined(IPV6_V6ONLY)
                if(v6only) {
                        int val=(v6only==2)?0:1;
@@ -500,6 +504,39 @@ create_udp_sock(int family, int socktype, struct sockaddr* addr,
                        return -1;
                }
 # endif /* IPv6 MTU */
+# if defined(IPV6_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
+#  if defined(IP_PMTUDISC_OMIT)
+               action = IP_PMTUDISC_OMIT;
+               if (setsockopt(s, IPPROTO_IPV6, IPV6_MTU_DISCOVER,
+                       &action, (socklen_t)sizeof(action)) < 0) {
+
+                       if (errno != EINVAL) {
+                               log_err("setsockopt(..., IPV6_MTU_DISCOVER, IP_PMTUDISC_OMIT...) failed: %s",
+                                       strerror(errno));
+                               sock_close(s);
+                               *noproto = 0;
+                               *inuse = 0;
+                               return -1;
+                       }
+               }
+               else
+               {
+                   omit6_set = 1;
+               }
+#  endif
+               if (omit6_set == 0) {
+                       action = IP_PMTUDISC_DONT;
+                       if (setsockopt(s, IPPROTO_IPV6, IPV6_MTU_DISCOVER,
+                               &action, (socklen_t)sizeof(action)) < 0) {
+                               log_err("setsockopt(..., IPV6_MTU_DISCOVER, IP_PMTUDISC_DONT...) failed: %s",
+                                       strerror(errno));
+                               sock_close(s);
+                               *noproto = 0;
+                               *inuse = 0;
+                               return -1;
+                       }
+               }
+# endif /* IPV6_MTU_DISCOVER */
        } else if(family == AF_INET) {
 #  if defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DONT)
 /* linux 3.15 has IP_PMTUDISC_OMIT, Hannes Frederic Sowa made it so that