This patch fixes an incompatibility between Windows and Linux with regards to
RFC 2553 [1].

Linux is in compliance with the RFC, which states that binding an IPv6 wildcard
address to a port should also bind the IPv4 wildcard address to the port.  This
causes problems when an application tries all available protocols and then
receives ``address in use'' when trying to bind with IPv4.

Windows [2] and OpenBSD [3] are not in compliance with this behavior.

The patch sets IPV6_V6ONLY, if available (note that it is also available for
OpenBSD), which disables the behavior.

[1] http://www.faqs.org/rfcs/rfc2553.html
[2] http://www.microsoft.com/technet/network/ipv6/ipv6faq.mspx
[3] http://www.openbsd.org/cgi-bin/man.cgi?query=inet6&sektion=4

---
 dlls/ws2_32/socket.c |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)

diff --git a/dlls/ws2_32/socket.c b/dlls/ws2_32/socket.c
index 13878a7..fa486bf 100644
--- a/dlls/ws2_32/socket.c
+++ b/dlls/ws2_32/socket.c
@@ -1405,6 +1405,18 @@ int WINAPI WS_bind(SOCKET s, const struct WS_sockaddr* name, int namelen)
             }
             else
             {
+#ifdef IPV6_V6ONLY
+                const struct sockaddr_in6 *in6 = (const struct sockaddr_in6*) &uaddr;
+                if (name->sa_family == WS_AF_INET6 &&
+                    !memcmp(&in6->sin6_addr, &in6addr_any, sizeof(struct in6_addr))) {
+                    int enable = 1;
+                    if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &enable, sizeof(enable)) == -1) {
+                        SetLastError(WSAEAFNOSUPPORT);
+                        return INVALID_SOCKET;
+                    }
+                }
+#endif
+
                 if (bind(fd, &uaddr.addr, uaddrlen) < 0)
                 {
                     int loc_errno = errno;
-- 
1.5.3.2