From owner-freebsd-net Fri Feb 22 9:44: 5 2002 Delivered-To: freebsd-net@freebsd.org Received: from wall.polstra.com (wall-gw.polstra.com [206.213.73.130]) by hub.freebsd.org (Postfix) with ESMTP id 8FFCE37B400 for ; Fri, 22 Feb 2002 09:44:00 -0800 (PST) Received: from vashon.polstra.com (vashon.polstra.com [206.213.73.13]) by wall.polstra.com (8.11.3/8.11.3) with ESMTP id g1MHhwn20490; Fri, 22 Feb 2002 09:43:58 -0800 (PST) (envelope-from jdp@wall.polstra.com) Received: (from jdp@localhost) by vashon.polstra.com (8.11.6/8.11.0) id g1MHhwh38542; Fri, 22 Feb 2002 09:43:58 -0800 (PST) (envelope-from jdp) Date: Fri, 22 Feb 2002 09:43:58 -0800 (PST) Message-Id: <200202221743.g1MHhwh38542@vashon.polstra.com> To: net@freebsd.org From: John Polstra Cc: jre@IPRG.nokia.com Subject: Re: incorrect checksums with xl? In-Reply-To: <3C7682BF.99A66C3B@iprg.nokia.com> References: <3C7547E0.8050805@isi.edu> <3C767749.3020302@isi.edu> <200202221730.g1MHU6938450@vashon.polstra.com> <3C7682BF.99A66C3B@iprg.nokia.com> Organization: Polstra & Co., Seattle, WA Sender: owner-freebsd-net@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org In article <3C7682BF.99A66C3B@iprg.nokia.com>, Joe Eykholt wrote: > > It seems like along with the packet being sent up to bpf, there's > a need for some flags that tell tcpdump about the packet. I haven't > looked at the current implementation, but in another system, I found > it useful to add a flag indicating whether the packet was being received > or transmitted. > > Adding a flag indicating that no checksum generation has been done yet, > but will be done by the NIC, would allow tcpdump to also ignore checksum > errors on outgoing packets, or it could generate the checksum itself > if displaying those bytes (in a hex output, e.g.). Remember, bpf is used by many things besides tcpdump. Adding these flags would require extending the bpf API. They couldn't be added for the default case, because that would break compatibility with other applications. They'd have to be enabled specifically, by means of a new ioctl. John -- John Polstra John D. Polstra & Co., Inc. Seattle, Washington USA "Disappointment is a good sign of basic intelligence." -- Chögyam Trungpa To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message