From e0c31f4794ef637b74b0a0074364ff407ca40d5a Mon Sep 17 00:00:00 2001 From: Zdenek Dohnal Date: Fri, 15 Dec 2023 10:59:54 +0100 Subject: [PATCH] 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). --- CHANGES.md | 2 ++ cups/http-addrlist.c | 43 ++++++++++++++++++++++++++++++------------- 2 files changed, 32 insertions(+), 13 deletions(-) diff --git a/cups/http-addrlist.c b/cups/http-addrlist.c index 198d073d0..cffcf184c 100644 --- a/cups/http-addrlist.c +++ b/cups/http-addrlist.c @@ -318,21 +318,38 @@ httpAddrConnect2( { # ifdef HAVE_POLL 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))) -- 2.43.0