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      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 #include <sys/cdefs.h>
     23 #ifndef lint
     24 __RCSID("$NetBSD: print-ipcomp.c,v 1.8 2024/09/02 16:15:31 christos Exp $");
     25 #endif
     26 
     27 /* \summary: IP Payload Compression Protocol (IPComp) printer */
     28 
     29 #include <config.h>
     30 
     31 #include "netdissect-stdinc.h"
     32 
     33 #include "netdissect.h"
     34 #include "extract.h"
     35 
     36 struct ipcomp {
     37 	nd_uint8_t  comp_nxt;	/* Next Header */
     38 	nd_uint8_t  comp_flags;	/* Length of data, in 32bit */
     39 	nd_uint16_t comp_cpi;	/* Compression parameter index */
     40 };
     41 
     42 void
     43 ipcomp_print(netdissect_options *ndo, const u_char *bp)
     44 {
     45 	const struct ipcomp *ipcomp;
     46 	uint16_t cpi;
     47 
     48 	ndo->ndo_protocol = "ipcomp";
     49 	ipcomp = (const struct ipcomp *)bp;
     50 	cpi = GET_BE_U_2(ipcomp->comp_cpi);
     51 
     52 	ND_PRINT("IPComp(cpi=0x%04x)", cpi);
     53 
     54 	/*
     55 	 * XXX - based on the CPI, we could decompress the packet here.
     56 	 * Packet buffer management is a headache (if we decompress,
     57 	 * packet will become larger).
     58 	 *
     59 	 * We would decompress the packet and then call a routine that,
     60 	 * based on ipcomp->comp_nxt, dissects the decompressed data.
     61 	 *
     62 	 * Until we do that, however, we just return -1, so that
     63 	 * the loop that processes "protocol"/"next header" types
     64 	 * stops - there's nothing more it can do with a compressed
     65 	 * payload.
     66 	 */
     67 }
     68