httpAddrConnect2: Check for error if POLLHUP is in valid revents

Some Linux kernel versions put POLLOUT|POLLHUP into revents when client tries to connect with httpAddrConnect2(), which makes the connection fail.
Let's check the option SO_ERROR before scratching the attempt - if there is no error, remove POLLHUP from revents.

I've re-purposed previously Solaris-only code to be used everywhere if the conditions are met - this should prevent bigger delays than necessary.

Slightly different issue than #827, but with similar symptoms (kernel sending POLLOUT|POLLHUP).

diff --git a/cups/http-addrlist.c b/cups/http-addrlist.c
index 28f16a319801c73dfa29779891f74ea15b8dca78..436e21f8a2082444e4624e4641f6665c6df424f5 100644 (file)
--- a/cups/http-addrlist.c
+++ b/cups/http-addrlist.c
@@ -288,21 +288,38 @@ httpAddrConnect2(
       for (i = 0; i < nfds; i ++)
       {
        DEBUG_printf("pfds[%d].revents=%x\n", i, pfds[i].revents);
-#  ifdef __sun
-       // Solaris connect runs asynchronously returning EINPROGRESS. Following
-       // poll() does not detect the socket is not connected and returns
-       // POLLIN|POLLOUT. Check the connection status and update error flag.
-       int            sres, serr;
-       socklen_t      slen = sizeof(serr);
-       sres = getsockopt(fds[i], SOL_SOCKET, SO_ERROR, &serr, &slen);
-       if (sres || serr)
+
+#  ifdef _WIN32
+       if (((WSAGetLastError() == WSAEINPROGRESS) && (pfds[i].revents & POLLIN) && (pfds[i].revents & POLLOUT)) ||
+           ((pfds[i].revents & POLLHUP) && (pfds[i].revents & (POLLIN|POLLOUT))))
+#  else
+       if (((errno == EINPROGRESS) && (pfds[i].revents & POLLIN) && (pfds[i].revents & POLLOUT)) ||
+           ((pfds[i].revents & POLLHUP) && (pfds[i].revents & (POLLIN|POLLOUT))))
+#  endif /* _WIN32 */
        {
-         pfds[i].revents |= POLLERR;
-#    ifdef DEBUG
-         DEBUG_printf(("1httpAddrConnect2: getsockopt returned: %d with error: %s", sres, strerror(serr)));
-#    endif
+         // Some systems generate POLLIN or POLLOUT together with POLLHUP when doing
+         // asynchronous connections. The solution seems to be to use getsockopt to
+         // check the SO_ERROR value and ignore the POLLHUP if there is no error or
+         // the error is EINPROGRESS.
+
+         int       sres,                /* Return value from getsockopt() - 0, or -1 if error */
+                   serr;                /* Option SO_ERROR value */
+         socklen_t slen = sizeof(serr); /* Option value size */
+
+         sres = getsockopt(fds[i], SOL_SOCKET, SO_ERROR, &serr, &slen);
+
+         if (sres || serr)
+         {
+           pfds[i].revents |= POLLERR;
+#  ifdef DEBUG
+           DEBUG_printf(("1httpAddrConnect2: getsockopt returned: %d with error: %s", sres, strerror(serr)));
+#  endif
+         }
+         else if (pfds[i].revents && (pfds[i].revents & POLLHUP) && (pfds[i].revents & (POLLIN | POLLOUT)))
+         {
+           pfds[i].revents &= ~POLLHUP;
+         }
        }
-#  endif // __sun
 
 
        if (pfds[i].revents && !(pfds[i].revents & (POLLERR | POLLHUP)))