diff options
Diffstat (limited to 'winsup/cygwin/net.cc')
| -rw-r--r-- | winsup/cygwin/net.cc | 19 |
1 files changed, 14 insertions, 5 deletions
diff --git a/winsup/cygwin/net.cc b/winsup/cygwin/net.cc index e6d9638c8..ec6f1f801 100644 --- a/winsup/cygwin/net.cc +++ b/winsup/cygwin/net.cc @@ -706,12 +706,21 @@ 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); - /* On systems supporting "enhanced socket security (2K3 and later), - the default behaviour of stream 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(). */ + /* Per POSIX we must not be able to reuse a complete duplicate of a + local TCP address (same IP, same port), even if SO_REUSEADDR has been + set. That's unfortunately possible in WinSock, and this has never + been changed to maintain backward compatibility. Instead, the + SO_EXCLUSIVEADDRUSE option has been added to allow an application to + request POSIX standard behaviour in the non-SO_REUSEADDR case. + + However, the WinSock standard behaviour of stream socket binding + is equivalent to the POSIX behaviour as if SO_REUSEADDR has been set. + So what we do here is to note that SO_REUSEADDR has been set, but not + actually hand over the request to WinSock. This is tested in + fhandler_socket::bind(), so that SO_EXCLUSIVEADDRUSE can be set if + the application did not set SO_REUSEADDR. This should reflect the + POSIX socket binding behaviour as close as possible with WinSock. */ if (level == SOL_SOCKET && optname == SO_REUSEADDR - && wincap.has_enhanced_socket_security () && fh->get_socket_type () == SOCK_STREAM) res = 0; else |