The Tcpdump Group git mirrors - tcpdump/blob - print-ipcomp.c

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 /* \summary: IP Payload Compression Protocol (IPComp) printer */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include "netdissect-stdinc.h"
  29
  30 #include "netdissect.h"
  31 #include "extract.h"
  32
  33 struct ipcomp {
  34         nd_uint8_t  comp_nxt;   /* Next Header */
  35         nd_uint8_t  comp_flags; /* Length of data, in 32bit */
  36         nd_uint16_t comp_cpi;   /* Compression parameter index */
  37 };
  38
  39 void
  40 ipcomp_print(netdissect_options *ndo, const u_char *bp)
  41 {
  42         const struct ipcomp *ipcomp;
  43         uint16_t cpi;
  44
  45         ndo->ndo_protocol = "ipcomp";
  46         ipcomp = (const struct ipcomp *)bp;
  47         ND_TCHECK_SIZE(ipcomp);
  48         cpi = EXTRACT_BE_U_2(ipcomp->comp_cpi);
  49
  50         ND_PRINT("IPComp(cpi=0x%04x)", cpi);
  51
  52         /*
  53          * XXX - based on the CPI, we could decompress the packet here.
  54          * Packet buffer management is a headache (if we decompress,
  55          * packet will become larger).
  56          *
  57          * We would decompress the packet and then call a routine that,
  58          * based on ipcomp->comp_nxt, dissects the decompressed data.
  59          *
  60          * Until we do that, however, we just return -1, so that
  61          * the loop that processes "protocol"/"next header" types
  62          * stops - there's nothing more it can do with a compressed
  63          * payload.
  64          */
  65         return;
  66
  67 trunc:
  68         nd_print_trunc(ndo);
  69         return;
  70 }