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Date:      Mon, 7 Jul 1997 19:23:29 -0700 (PDT)
From:      Archie Cobbs <archie@whistle.com>
To:        FreeBSD-gnats-submit@FreeBSD.ORG
Subject:   kern/4052: VJ compression drops packets with IP+TCP header length > MLEN
Message-ID:  <199707080223.TAA18159@bubba.whistle.com>
Resent-Message-ID: <199707080230.TAA22656@hub.freebsd.org>

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>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:



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