------------------------------------------------------------
revno: 13863
revision-id: squid3@treenet.co.nz-20150716070137-l130moshh3wk96eg
parent: squid3@treenet.co.nz-20150716070012-sgalrl71wps83uss
committer: Amos Jeffries <squid3@treenet.co.nz>
branch nick: 3.5
timestamp: Thu 2015-07-16 00:01:37 -0700
message:
  IPv6: improve BCP 177 compliance
  
  Always perform the IP transport probes to detect IPv6 availability.
  
  * Accept lack of IPv6 assignment as per normal by auto-disabling IPv6.
  
  * Whine loudly if (and only if) it would have worked but has been
    forced OFF by --disable-ipv6.
------------------------------------------------------------
# Bazaar merge directive format 2 (Bazaar 0.90)
# revision_id: squid3@treenet.co.nz-20150716070137-l130moshh3wk96eg
# target_branch: http://bzr.squid-cache.org/bzr/squid3/3.5
# testament_sha1: 91282a68ed8d3e43745e80ddcab83939676e9455
# timestamp: 2015-07-16 07:16:05 +0000
# source_branch: http://bzr.squid-cache.org/bzr/squid3/3.5
# base_revision_id: squid3@treenet.co.nz-20150716070012-\
#   sgalrl71wps83uss
# 
# Begin patch
=== modified file 'src/ip/tools.cc'
--- src/ip/tools.cc	2015-01-13 09:13:49 +0000
+++ src/ip/tools.cc	2015-07-16 07:01:37 +0000
@@ -30,7 +30,6 @@
 void
 Ip::ProbeTransport()
 {
-#if USE_IPV6
     // check for usable IPv6 sockets
     int s = socket(PF_INET6, SOCK_STREAM, 0);
     if (s < 0) {
@@ -56,12 +55,18 @@
     debugs(3, 2, "Missing RFC 3493 compliance - attempting split IPv4 and IPv6 stacks ...");
     EnableIpv6 |= IPV6_SPECIAL_SPLITSTACK;
 #endif
+    // TODO: attempt to use the socket to connect somewhere ?
+    //  needs to be safe to contact and with guaranteed working IPv6 at the other end.
     close(s);
 
+#if USE_IPV6
     debugs(3, 2, "IPv6 transport " << (EnableIpv6?"Enabled":"Disabled"));
 #else
-    debugs(3, 2, "IPv6 transport forced OFF by build parameters.");
-    EnableIpv6 = IPV6_OFF;
+    debugs(3, 2, "IPv6 transport " << (EnableIpv6?"Available":"Disabled"));
+    if (EnableIpv6 != IPV6_OFF) {
+        debugs(3, DBG_CRITICAL, "WARNING: BCP 177 violation. IPv6 transport forced OFF by build parameters.");
+        EnableIpv6 = IPV6_OFF;
+    }
 #endif
 }