You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
121 lines
4.4 KiB
121 lines
4.4 KiB
/*
|
|
* Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997
|
|
* The Regents of the University of California. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that: (1) source code distributions
|
|
* retain the above copyright notice and this paragraph in its entirety, (2)
|
|
* distributions including binary code include the above copyright notice and
|
|
* this paragraph in its entirety in the documentation or other materials
|
|
* provided with the distribution, and (3) all advertising materials mentioning
|
|
* features or use of this software display the following acknowledgement:
|
|
* ``This product includes software developed by the University of California,
|
|
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
|
|
* the University nor the names of its contributors may be used to endorse
|
|
* or promote products derived from this software without specific prior
|
|
* written permission.
|
|
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
|
|
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
|
|
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
|
|
*/
|
|
|
|
/* \summary: PPP Van Jacobson compression printer */
|
|
|
|
/* specification: RFC 1144 */
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include "config.h"
|
|
#endif
|
|
|
|
#include <netdissect-stdinc.h>
|
|
|
|
#include "netdissect.h"
|
|
#include "slcompress.h"
|
|
#include "ppp.h"
|
|
|
|
/*
|
|
* XXX - for BSD/OS PPP, what packets get supplied with a PPP header type
|
|
* of PPP_VJC and what packets get supplied with a PPP header type of
|
|
* PPP_VJNC? PPP_VJNC is for "UNCOMPRESSED_TCP" packets, and PPP_VJC
|
|
* is for COMPRESSED_TCP packets (PPP_IP is used for TYPE_IP packets).
|
|
*
|
|
* RFC 1144 implies that, on the wire, the packet type is *not* needed
|
|
* for PPP, as different PPP protocol types can be used; it only needs
|
|
* to be put on the wire for SLIP.
|
|
*
|
|
* It also indicates that, for compressed SLIP:
|
|
*
|
|
* If the COMPRESSED_TCP bit is set in the first byte, it's
|
|
* a COMPRESSED_TCP packet; that byte is the change byte, and
|
|
* the COMPRESSED_TCP bit, 0x80, isn't used in the change byte.
|
|
*
|
|
* If the upper 4 bits of the first byte are 7, it's an
|
|
* UNCOMPRESSED_TCP packet; that byte is the first byte of
|
|
* the UNCOMPRESSED_TCP modified IP header, with a connection
|
|
* number in the protocol field, and with the version field
|
|
* being 7, not 4.
|
|
*
|
|
* Otherwise, the packet is an IPv4 packet (where the upper 4 bits
|
|
* of the packet are 4).
|
|
*
|
|
* So this routine looks as if it's sort-of intended to handle
|
|
* compressed SLIP, although it doesn't handle UNCOMPRESSED_TCP
|
|
* correctly for that (it doesn't fix the version number and doesn't
|
|
* do anything to the protocol field), and doesn't check for COMPRESSED_TCP
|
|
* packets correctly for that (you only check the first bit - see
|
|
* B.1 in RFC 1144).
|
|
*
|
|
* But it's called for BSD/OS PPP, not SLIP - perhaps BSD/OS does weird
|
|
* things with the headers?
|
|
*
|
|
* Without a BSD/OS VJC-compressed PPP trace, or knowledge of what the
|
|
* BSD/OS VJC code does, we can't say what's the case.
|
|
*
|
|
* We therefore leave "proto" - which is the PPP protocol type - in place,
|
|
* *not* marked as unused, for now, so that GCC warnings about the
|
|
* unused argument remind us that we should fix this some day.
|
|
*
|
|
* XXX - also, it fetches the TCP checksum field in COMPRESSED_TCP
|
|
* packets directly, rather than with EXTRACT_16BITS(); RFC 1144 says
|
|
* it's "the unmodified TCP checksum", which would imply that it's
|
|
* big-endian, but perhaps, on the platform where this was developed,
|
|
* the packets were munged by the networking stack before being handed
|
|
* to the packet capture mechanism.
|
|
*/
|
|
int
|
|
vjc_print(netdissect_options *ndo, register const char *bp, u_short proto _U_)
|
|
{
|
|
int i;
|
|
|
|
switch (bp[0] & 0xf0) {
|
|
case TYPE_IP:
|
|
if (ndo->ndo_eflag)
|
|
ND_PRINT((ndo, "(vjc type=IP) "));
|
|
return PPP_IP;
|
|
case TYPE_UNCOMPRESSED_TCP:
|
|
if (ndo->ndo_eflag)
|
|
ND_PRINT((ndo, "(vjc type=raw TCP) "));
|
|
return PPP_IP;
|
|
case TYPE_COMPRESSED_TCP:
|
|
if (ndo->ndo_eflag)
|
|
ND_PRINT((ndo, "(vjc type=compressed TCP) "));
|
|
for (i = 0; i < 8; i++) {
|
|
if (bp[1] & (0x80 >> i))
|
|
ND_PRINT((ndo, "%c", "?CI?SAWU"[i]));
|
|
}
|
|
if (bp[1])
|
|
ND_PRINT((ndo, " "));
|
|
ND_PRINT((ndo, "C=0x%02x ", bp[2]));
|
|
ND_PRINT((ndo, "sum=0x%04x ", *(const u_short *)&bp[3]));
|
|
return -1;
|
|
case TYPE_ERROR:
|
|
if (ndo->ndo_eflag)
|
|
ND_PRINT((ndo, "(vjc type=error) "));
|
|
return -1;
|
|
default:
|
|
if (ndo->ndo_eflag)
|
|
ND_PRINT((ndo, "(vjc type=0x%02x) ", bp[0] & 0xf0));
|
|
return -1;
|
|
}
|
|
}
|