* fhandler_socket.cc (fhandler_socket::bind): Don't run explicit

	local socket test in SO_REUSEADDR case on systems supporting
	enhanced socket security.  Explain why.  Only call address_in_use
	for AF_INET sockets.
	* net.cc (cygwin_setsockopt): Don't call setsockopt to set SO_REUSEADDR
	on systems supporting enhanced socket security.  Add comment.
	* wincap.h (wincaps::has_enhanced_socket_security): New element.
	* wincap.cc: Implement above element throughout.

1 files changed, 10 insertions, 2 deletions

diff --git a/winsup/cygwin/net.cc b/winsup/cygwin/net.cc
index ded37aa05..8be32197c 100644
--- a/winsup/cygwin/net.cc
+++ b/winsup/cygwin/net.cc
@@ -649,8 +649,16 @@ cygwin_setsockopt (int fd, int level, int optname, const void *optval,
       if (level == IPPROTO_IP && CYGWIN_VERSION_CHECK_FOR_USING_WINSOCK1_VALUES)
 	optname = convert_ws1_ip_optname (optname);
 
-      res = setsockopt (fh->get_socket (), level, optname,
-			(const char *) optval, optlen);
+      /* On systems supporting "enhanced socket security (2K3 and later),
+	 the default behaviour of socket binding is equivalent to the POSIX
+	 behaviour with SO_REUSEADDR.  Setting SO_REUSEADDR would only result
+	 in wrong behaviour.  See also fhandler_socket::bind(). */
+      if (level == SOL_SOCKET && optname == SO_REUSEADDR
+	  && wincap.has_enhanced_socket_security ())
+	res = 0;
+      else
+	res = setsockopt (fh->get_socket (), level, optname,
+			  (const char *) optval, optlen);
 
       if (optlen == 4)
 	syscall_printf ("setsockopt optval=%x", *(long *) optval);