From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x235.google.com (mail-lj1-x235.google.com [IPv6:2a00:1450:4864:20::235]) by sourceware.org (Postfix) with ESMTPS id 6EC73386181F; Mon, 13 Jul 2020 13:06:01 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 6EC73386181F Received: by mail-lj1-x235.google.com with SMTP id s9so17690015ljm.11; Mon, 13 Jul 2020 06:06:01 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=GRRkyzff5zzkVB156cKk/y5vXUBRKJb6f/GmzdjszEU=; b=GhXvVwpBIGQUxzti+MryY8nzvV54L7dKoSaOB0Mxr5jGnrldResH/swa3yOFipQIMv SNPq5VaExufpRM3SlaO4lOnp/ssQaxwSzMIWKQAA9ViG4UgRxcdXeWka5JgS2OYcjw8f Mr1lE9HAR/zHuVOcZvTuJpx/JpIrmcvMiBG+Tfr69okt8mEpNSBHAZgCWqOvnFhvPZvT harE9cKz/h0WQ5MikQ/wpttHAZzRVsNKkTsN5n1BQYjEUP819zAu/lg081OyRijG4GbO lyBMyRTn5Q3ilMHSj4QqFrrVHHNX0o/2yvmDUQzxp6FijoUp0PqX779a4fDyLJQKh01F d9rg== X-Gm-Message-State: AOAM530ME0q22tciUyzsqUSMt/JGft4ESvn4aMjtAudrqe1itOD0NBDv gkmvNb8RWiKpabmsYlRQBY8LXI/f0uukwDcSyNwhv+UC7iiq9bk= X-Google-Smtp-Source: ABdhPJzugrMKu2xaN9LYk1xUfyFcAe7R76WVW3KWee+YyLuwNzAaBter+cFjl7Umh663A6yqReRl7wvoEVArXpkey2Y= X-Received: by 2002:a2e:9907:: with SMTP id v7mr28653452lji.347.1594645559802; Mon, 13 Jul 2020 06:05:59 -0700 (PDT) MIME-Version: 1.0 References: <20200630111215.GE3499@calimero.vinschen.de> <20200630165358.GG3499@calimero.vinschen.de> <20200701195027.GL3499@calimero.vinschen.de> In-Reply-To: From: Cary Lewis Date: Mon, 13 Jul 2020 09:05:49 -0400 Message-ID: Subject: Re: TCP_KEEPINVTL and TCP_KEEPIDLE - Socket Keep Alives not working To: cygwin@cygwin.com, corinna-cygwin@cygwin.com X-Spam-Status: No, score=-3.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: cygwin@cygwin.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: General Cygwin discussions and problem reports List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 13 Jul 2020 13:06:03 -0000 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 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 > 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 >> >