On Mon, 16 May 2011, Jacob Eiler wrote: > I am experiencing an issue with getsockopt when running an application > under CygWin. > > The application (Kannel sms gateway) creates a new socket, attempt to > connect non-blocking to the other host and later calls getsockopt to > check for errors: > > s = socket(PF_INET, SOCK_STREAM, 0); > ... > flags = fcntl(s, F_GETFL, 0); > fcntl(s, F_SETFL, flags | O_NONBLOCK); > ... > connect(s, &addr, sizeof(addr)) > > connect returns EINPROGRESS and the application has a polling thread > setup to handle timeout and check for changes. In both cases a callback > function is invoked. > > The callback function checks the connection by calling > > getsockopt(s, SOL_SOCKET, SO_ERROR, &err, &len) > > but it returns 0 and no error - even if the connection was never > established. Subsequently the application tries to write data to the > socket - which fails with a "transport endpoint is not connected" error. > > The code works just fine on Linux with getsockopt returning an error. > Any pointer on how to get this working will be greatly appreciated.
The following pseudo code works portably for me on Solaris and Cygwin: fds.fd = s; fds.events = POLL_WRITE; if (Poll(&fds, 1, 0) > 0) { len = sizeof(errno); getsockopt(fd, SOL_SOCKET, SO_ERROR, &errno, &len) if (errno = 0) ; //connected } I think the key is to make sure select/poll returns (as either writable or with error) before calling getsockopt(SO_ERROR). HTH. -- Brian Ford Staff Realtime Software Engineer VITAL - Visual Simulation Systems FlightSafety International the best safety device in any aircraft is a well-trained crew... -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple