Corinna, thank you. I have tested and confirmed that the patched cywin1.dll, and include files /usr/include/netinet/tcp.h and /usr/include/cygwin/socket.h, work as expected after I re-compile and link curl (specifically lib/connect.c).
I look forward to seeing this patch included in a future release, and hopefully that will include rebuilt versions of curl, and other network utilities, such as wget, nc, etc. It's always a pleasure working with you. On Thu, Jul 2, 2020 at 10:52 AM Cary Lewis <cary.le...@gmail.com> wrote: > That's amazing, thanks. We'll have to try to recompile curl under cygwin > to confirm that it keeps up the constants, and then does the right posix > calls. > > I will grab the files, and try to have this tested and report back to you. > > Take care, > > Cary Lewis > > On Wed, Jul 1, 2020 at 3:51 PM Corinna Vinschen <corinna-cyg...@cygwin.com> > wrote: > >> On Jun 30 18:53, Corinna Vinschen wrote: >> > On Jun 30 09:46, Cary Lewis via Cygwin wrote: >> > > Thanks for the reply. The answer to your question is that the 2 hour >> keep >> > > alive was not sufficient for a particular use case I encountered. >> > > >> > > I was trying to use curl under cygwin to access a very slow REST >> endpoint >> > > that was taking up to 8 minutes to generate download before any data >> flowed >> > > back to the client. This caused the server to abort the socket. >> > > >> > > Accessing the endpoint in chrome or firefox revealed that they set a >> > > keepalive to 45 seconds, which kept the server happy. >> > > >> > > Attempting to set --keepalive-time=45 in cygwin's curl didn't work, >> and >> > > wireshark revealed that no keepalives were being sent. >> > > >> > > I will attempt to patch cygwin, I got the build to work. Can you >> point me >> > > in the right direction, in terms of where the socket calls get mapped >> to >> > > the winsock calls? >> > >> > Actually, while I'm usually happy to take contributions, you don't have >> > to dig into that yourself. I already have a few local patches in the >> > loop changing some of the affected code. I have a good idea what's >> > required to add the keep-alive socket options to that code, so just lay >> > back and stay tuned for now. >> >> Ok, so I added support for a couple more IPPROTO_TCP socket options. >> First of all I fixed TCP_MAXSEG which was using the BSD value, rather >> than the WinSock value. Then I added TCP_FASTOPEN, TCP_KEEPIDLE, >> TCP_KEEPCNT, TCP_KEEPINTVL, TCP_QUICKACK and TCP_USER_TIMEOUT: >> >> - TCP_FASTOPEN is supported since W10 1607, it's just faked on older >> systems. >> >> - TCP_KEEPIDLE, TCP_KEEPCNT, TCP_KEEPINTVL are using the options >> of the same name since W10 1709, WSAIoctl(SIO_KEEPALIVE_VALS) >> on older systems. >> >> But here's a problem: Older systems didn't allow to change >> TCP_KEEPCNT. It is always fixed to 10. Mulling over that problem in >> the shower, I came up with the following solution: >> >> The max keep-alive timeout is TCP_KEEPIDLE + TCP_KEEPCNT * >> TCP_KEEPINTVL. >> This should stay the same from a user space perspective. So the current >> code tweaks the TCP_KEEPINTVL given to WinSock so that >> >> TCP_KEEPCNT * user space TCP_KEEPINTVL == 10 * WinSock TCP_KEEPINTVL >> >> Example: user space TCP_KEEPCNT 4, TCP_KEEPINTVL 5 (4 * 5 == 20) >> ==> WinSock TCP_KEEPCNT 10, TCP_KEEPINTVL 2 (10 * 2 == 20) >> >> I hope that makes sense. >> >> - TCP_USER_TIMEOUT is supported with msec granularity since W10 1607 >> (called TCP_MAXRTMS), with 1 secs granularity on older systems >> (called TCP_MAXRT). Use the latter on older systems under the expected >> loss of precision. >> >> - TCP_QUICKACK is supposedly supported on Windows as a socket option >> but it's still not clear if the net got that right so far. However, >> there's WSAIoctl(SIO_TCP_SET_ACK_FREQUENCY) doing the same. >> >> I uploaded developer snapshots to https://cygwin.com/snapshots/, >> please test. >> >> For testing, you'll need at least the DLL, plus the changed headers >> cygwin/socket.h and netinet/tcp.h from the complete tar file >> cygwin-20200701.tar.xz. Or, just take the DLL and fetch the headers >> right from the git repo. >> >> >> Thanks, >> Corinna >> >> -- >> Corinna Vinschen >> Cygwin Maintainer >> -- >> Problem reports: https://cygwin.com/problems.html >> FAQ: https://cygwin.com/faq/ >> Documentation: https://cygwin.com/docs.html >> Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple >> > -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
