Date: Wed, 28 Nov 2001 13:02:41 +1100 From: Edwin Groothuis <edwin@mavetju.org> To: Bob Hall <rjhalljr@starpower.net> Cc: freebsd-questions@freebsd.org Subject: Re: RFC 1122 and the Urgent flag Message-ID: <20011128130241.G579@k7.mavetju.org> In-Reply-To: <20011127202507.A960@starpower.net>; from rjhalljr@starpower.net on Tue, Nov 27, 2001 at 08:28:08PM -0500 References: <20011127202507.A960@starpower.net>
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On Tue, Nov 27, 2001 at 08:28:08PM -0500, Bob Hall wrote: > I've been studying the OReilly Internet protocols book and I > found a paragraph that says that many BSD systems are not > compliant with RFC 1122 in how they deal with the Urgent flag. > The book is at least two years old now, so I'm wondering if > this is still true, and specifically, if it is true for > FreeBSD. This isn't an urgent question, but I've done a > search in the list archives and on google and haven't found > an answer. No apps will die if I don't get an answer, it > just relates to something I'm studying. According to Richard Stevens TCP/IP Illustrated Volume 1 section 20.8 on page 292 and following (which I had accidently laying open on the TCP setup): There is continuing debate about whether the urgent pointer points to the last byte of urgent data, or to the byte following the last byte of urgent data. The original TCP specification gave both interpretations but the Host Requirements RFC identifies which is correct: the urgent pointer points to the last byte of urgent data. The problem, however, is that most implementations (i.e., the Berkeley-derived implementations) continue to use the wrong interpretation. An implementation that follows the specification in the Host Requirements RFC might be compliant, but might not communicate correctly with most other hosts. Edwin -- Edwin Groothuis | Personal website: http://www.MavEtJu.org edwin@mavetju.org | Interested in MUDs? Visit Fatal Dimensions: ------------------+ http://www.FatalDimensions.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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