From owner-freebsd-bugs  Mon Jul  7 19:30:08 1997
Return-Path: <owner-bugs>
Received: (from root@localhost)
          by hub.freebsd.org (8.8.5/8.8.5) id TAA22666
          for bugs-outgoing; Mon, 7 Jul 1997 19:30:08 -0700 (PDT)
Received: (from gnats@localhost)
          by hub.freebsd.org (8.8.5/8.8.5) id TAA22656;
          Mon, 7 Jul 1997 19:30:05 -0700 (PDT)
Resent-Date: Mon, 7 Jul 1997 19:30:05 -0700 (PDT)
Resent-Message-Id: <199707080230.TAA22656@hub.freebsd.org>
Resent-From: gnats (GNATS Management)
Resent-To: freebsd-bugs
Resent-Reply-To: FreeBSD-gnats@FreeBSD.ORG, archie@whistle.com
Received: from whistle.com (s205m131.whistle.com [207.76.205.131])
          by hub.freebsd.org (8.8.5/8.8.5) with ESMTP id TAA22475
          for <FreeBSD-gnats-submit@freebsd.org>; Mon, 7 Jul 1997 19:24:20 -0700 (PDT)
Received: (from smap@localhost) by whistle.com (8.7.5/8.6.12) id TAA27109 for <FreeBSD-gnats-submit@freebsd.org>; Mon, 7 Jul 1997 19:23:47 -0700 (PDT)
Received: from bubba.whistle.com(207.76.205.7) by whistle.com via smap (V1.3)
	id sma027105; Mon Jul  7 19:23:29 1997
Received: (from archie@localhost) by bubba.whistle.com (8.8.5/8.6.12) id TAA18159; Mon, 7 Jul 1997 19:23:29 -0700 (PDT)
Message-Id: <199707080223.TAA18159@bubba.whistle.com>
Date: Mon, 7 Jul 1997 19:23:29 -0700 (PDT)
From: Archie Cobbs <archie@whistle.com>
Reply-To: archie@whistle.com
To: FreeBSD-gnats-submit@FreeBSD.ORG
X-Send-Pr-Version: 3.2
Subject: kern/4052: VJ compression drops packets with IP+TCP header length > MLEN
Sender: owner-bugs@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk


>Number:         4052
>Category:       kern
>Synopsis:       VJ compression drops packets with IP+TCP header length > MLEN
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Jul  7 19:30:01 PDT 1997
>Last-Modified:
>Originator:     Archie Cobbs
>Organization:
Whistle Communications, Inc.
>Release:        FreeBSD 2.2-STABLE i386
>Environment:


>Description:

/sys/net/slcompress.h contains this definition:

  #define MAX_HDR MLEN   /* XXX 4bsd-ism: should really be 128 */

MLEN is 108 or therabouts. This means any packet with combined
IP and TCP header length greater than MLEN will be dropped when
Van Jacobson compression is enabled (ie., slip or ppp).

>How-To-Repeat:


>Fix:

One possibility...

1. Increase MAX_HDR to 128
2. Make sl_compress_tcp() and sl_uncompress_tcp() not require
   a contiguous buffer

>Audit-Trail:
>Unformatted: