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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-frag6.c,v 1.10 2026/03/19 00:05:13 christos Exp $");
     25 #endif
     26 
     27 /* \summary: IPv6 fragmentation header printer */
     28 
     29 #include <config.h>
     30 
     31 #include "netdissect-stdinc.h"
     32 
     33 #define ND_LONGJMP_FROM_TCHECK
     34 #include "netdissect.h"
     35 #include "extract.h"
     36 
     37 #include "ip6.h"
     38 
     39 int
     40 frag6_print(netdissect_options *ndo, const u_char *bp, const u_char *bp2)
     41 {
     42 	const struct ip6_frag *dp;
     43 	const struct ip6_hdr *ip6;
     44 
     45 	ndo->ndo_protocol = "frag6";
     46 	dp = (const struct ip6_frag *)bp;
     47 	ip6 = (const struct ip6_hdr *)bp2;
     48 
     49 	ND_PRINT("frag (");
     50 	if (ndo->ndo_vflag)
     51 		ND_PRINT("0x%08x:", GET_BE_U_4(dp->ip6f_ident));
     52 	else
     53 		ND_TCHECK_4(dp->ip6f_ident);
     54 	ND_PRINT("%u|", GET_BE_U_2(dp->ip6f_offlg) & IP6F_OFF_MASK);
     55 	if ((bp - bp2) + sizeof(struct ip6_frag) >
     56 	    sizeof(struct ip6_hdr) + GET_BE_U_2(ip6->ip6_plen))
     57 		ND_PRINT("[length < 0] (invalid))");
     58 	else
     59 		ND_PRINT("%zu)",
     60 			 sizeof(struct ip6_hdr) + GET_BE_U_2(ip6->ip6_plen) -
     61 			 (bp - bp2) - sizeof(struct ip6_frag));
     62 
     63 	/* it is meaningless to decode non-first fragment */
     64 	if ((GET_BE_U_2(dp->ip6f_offlg) & IP6F_OFF_MASK) != 0)
     65 		return -1;
     66 	else {
     67 		ND_PRINT(" ");
     68 		return sizeof(struct ip6_frag);
     69 	}
     70 }
     71