From owner-freebsd-net@FreeBSD.ORG Tue Jan 7 20:10:25 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id C3FF5598 for ; Tue, 7 Jan 2014 20:10:25 +0000 (UTC) Received: from mail-gg0-x22c.google.com (mail-gg0-x22c.google.com [IPv6:2607:f8b0:4002:c02::22c]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 779AF1953 for ; Tue, 7 Jan 2014 20:10:25 +0000 (UTC) Received: by mail-gg0-f172.google.com with SMTP id q6so114720ggc.17 for ; Tue, 07 Jan 2014 12:10:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wemm.org; s=google; h=message-id:date:from:organization:user-agent:mime-version:to :subject:references:in-reply-to:content-type; bh=N3moCUjvSszeiWQGRdyBkwIBQdB0r66vr2/CytyYTxM=; b=Pl2H8ldZ8bAZ4QcyZJSUi/9Dsjj1ITZOtvRXbIewJq85gJaCqMXfELZsypjcZ2zRvC bD4M8Q3FKJYLyYUlL/as8d4pwHw7AHIF9+Mn0mNBULIX4QmIJ6HH/9rnC48DW1IUNUND LSdGmgodhGR0RTuDEWRW7H+TDMi1+b2Duv4Ww= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:message-id:date:from:organization:user-agent :mime-version:to:subject:references:in-reply-to:content-type; bh=N3moCUjvSszeiWQGRdyBkwIBQdB0r66vr2/CytyYTxM=; b=AtHMoOooV45BNOXH68t0Wi4n8od0eZxlSCEg/6k57uSx57cuUxkT98RQT+kfNl5Xnz K9J7HimAohpxqUa2vYyOD4jteKLn2Q3llB5GpTmPsZIv4ClWZxIuE0p4smTcjBWasdEC LAdmEVEZ9fxXiJWAOEb0ld3cUt75Yi7h9SKADPVV8tM2XMpWdDzbwKAoBFf8K6aMKBtH Gn4d4Xr/VePjp0U5aZZeSRYwPxMFdB87b10/tlI0bQw+1hTVwc13URIVt8hV3CkXhUBH mF2tTCm9+EXEUZGtDK604p+tS7SslXSeHeNOTAVGeNPpXlcIZV98q+y75stExgC/UPGB Mq2A== X-Gm-Message-State: ALoCoQkGP1F/o5HLdZkQFOKAiZAP3l06+ruhRsPByHJex+nGby3GMvCEnKVoKM3s4ey3kmmXyJY2 X-Received: by 10.236.74.73 with SMTP id w49mr3860511yhd.87.1389125424518; Tue, 07 Jan 2014 12:10:24 -0800 (PST) Received: from hackintosh.wemm.org ([2601:9:e80:770:69a1:2b30:eab6:4149]) by mx.google.com with ESMTPSA id b30sm25508942yhm.5.2014.01.07.12.10.22 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Tue, 07 Jan 2014 12:10:23 -0800 (PST) Message-ID: <52CC5F2E.5030201@wemm.org> Date: Tue, 07 Jan 2014 12:10:22 -0800 From: Peter Wemm Organization: World Domination in progress. User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: freebsd-net@freebsd.org Subject: Re: TCP question: Is this simultaneous close handling broken? References: <52CB3AE9.3030107@wemm.org> In-Reply-To: <52CB3AE9.3030107@wemm.org> X-Enigmail-Version: 1.6 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="KcbDav8DVDNlExS7ASDrFxMrBqUjICjGW" X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 07 Jan 2014 20:10:25 -0000 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --KcbDav8DVDNlExS7ASDrFxMrBqUjICjGW Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable On 1/6/14, 3:23 PM, Peter Wemm wrote: > We've hit a weird problem at work when dealing with simultaneous closes= =2E > In this particular case, it's a FreeBSD-7.4 machine talking some random= > Linux host. >=20 > There is a client/server protocol in use, and both ends are doing a clo= se > at the same time. It might be a shutdown, I haven't seen all the code = yet. [..] > A packet capture, with relative timestamps: >=20 > 000050 freebsd.28411 > linux.14001: F 6486:6486(0) ack 232 > 000031 linux.14001 > freebsd.28411: F 232:232(0) ack 6486 > 000333 linux.14001 > freebsd.28411: . ack 6487 > [200ms retransmit timer fires on linux] > 200490 linux.14001 > freebsd.28411: F 232:232(0) ack 6487 > 000011 freebsd.28411 > linux.14001: . ack 233 [..] > What am I looking at? Who's at fault? It looks like we're failing to > recognize the ack for our fin. It definitely looks like FreeBSD at fault. We've simply not acked their = FIN until they retransmitted it. I've looked at the commit logs and I don't see anything obvious that stan= ds out to me for a fix for this. Most of the changes seem to be lock struct= ure changes than protocol fixes. I see things like ECN and other protocol features being added as well. Where should I look in the code? --=20 Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI6F= JV UTF-8: for when a ' just won\342\200\231t do. --KcbDav8DVDNlExS7ASDrFxMrBqUjICjGW Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iEYEARECAAYFAlLMXy4ACgkQFRKuUnJ3cX88nQCeLUtlGDcxkTWs9+bQoEm3sXJz Ay4AmwfEOyuOKCHgPl3Y4JfctaZDNIvx =T93F -----END PGP SIGNATURE----- --KcbDav8DVDNlExS7ASDrFxMrBqUjICjGW--