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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 /* \summary: IPv6 fragmentation header printer */
  23
  24 #include <config.h>
  25
  26 #include "netdissect-stdinc.h"
  27
  28 #define ND_LONGJMP_FROM_TCHECK
  29 #include "netdissect.h"
  30 #include "extract.h"
  31
  32 #include "ip6.h"
  33
  34 int
  35 frag6_print(netdissect_options *ndo, const u_char *bp, const u_char *bp2)
  36 {
  37         const struct ip6_frag *dp;
  38         const struct ip6_hdr *ip6;
  39
  40         ndo->ndo_protocol = "frag6";
  41         dp = (const struct ip6_frag *)bp;
  42         ip6 = (const struct ip6_hdr *)bp2;
  43
  44         ND_PRINT("frag (");
  45         if (ndo->ndo_vflag)
  46                 ND_PRINT("0x%08x:", GET_BE_U_4(dp->ip6f_ident));
  47         else
  48                 ND_TCHECK_4(dp->ip6f_ident);
  49         ND_PRINT("%u|", GET_BE_U_2(dp->ip6f_offlg) & IP6F_OFF_MASK);
  50         if ((bp - bp2) + sizeof(struct ip6_frag) >
  51             sizeof(struct ip6_hdr) + GET_BE_U_2(ip6->ip6_plen))
  52                 ND_PRINT("[length < 0] (invalid))");
  53         else
  54                 ND_PRINT("%zu)",
  55                          sizeof(struct ip6_hdr) + GET_BE_U_2(ip6->ip6_plen) -
  56                          (bp - bp2) - sizeof(struct ip6_frag));
  57
  58         /* it is meaningless to decode non-first fragment */
  59         if ((GET_BE_U_2(dp->ip6f_offlg) & IP6F_OFF_MASK) != 0)
  60                 return -1;
  61         else {
  62                 ND_PRINT(" ");
  63                 return sizeof(struct ip6_frag);
  64         }
  65 }