From owner-freebsd-hackers Thu Dec 6 8:28:14 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from snipe.prod.itd.earthlink.net (snipe.mail.pas.earthlink.net [207.217.120.62]) by hub.freebsd.org (Postfix) with ESMTP id EC14537B417 for ; Thu, 6 Dec 2001 08:28:09 -0800 (PST) Received: from dialup-209.245.132.144.dial1.sanjose1.level3.net ([209.245.132.144] helo=mindspring.com) by snipe.prod.itd.earthlink.net with esmtp (Exim 3.33 #1) id 16C1N5-0005Vr-00; Thu, 06 Dec 2001 08:27:39 -0800 Message-ID: <3C0F9C79.F0B32682@mindspring.com> Date: Thu, 06 Dec 2001 08:27:37 -0800 From: Terry Lambert X-Mailer: Mozilla 4.7 [en]C-CCK-MCD {Sony} (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Yung-Sheng Tang Cc: freebsd-hackers@freebsd.org Subject: Re: UDP checksum error after encapsulating multicast packet References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Yung-Sheng Tang wrote: > I am sorry that I don't get what you mean well. The multicast-sending > AP, mrouted and tcpdump all run on the same machine. From tcpdump > result, the multicast AP gives the right checksum, whereas > encapsulating module(?) gives the wrong checksum, right? So, What next > I should examine for? Ah. I thought you might have a bad source host. See Mark Tinguely's post: he found the problem; it's a byte-order at the tme of calculation problem. I think you would have to HTONS(), do the checksum recalculation, and then HTONS() it back (or delay the recalculation untul after it was naturally HTONS()'ed, if possible). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message