proto_ipv6_fragm.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * Copyright 2012 Markus Amend <markus@netsniff-ng.org>, Deutsche Flugsicherung GmbH
   4  * Subject to the GPL, version 2.
   5  *
   6  * IPv6 Fragmentation Header described in RFC2460
   7  */
   8
   9 #include <stdio.h>
  10 #include <stdint.h>
  11 #include <netinet/in.h>    /* for ntohs() */
  12
  13 #include "proto.h"
  14 #include "dissector_eth.h"
  15 #include "built_in.h"
  16 #include "pkt_buff.h"
  17
  18 struct fragmhdr {
  19         uint8_t h_fragm_next_header;
  20         uint8_t h_fragm_reserved;
  21         uint16_t h_fragm_off_res_M;
  22         uint32_t h_fragm_identification;
  23 } __packed;
  24
  25 static void fragm(struct pkt_buff *pkt)
  26 {
  27         uint16_t off_res_M;
  28         struct fragmhdr *fragm_ops;
  29
  30         fragm_ops = (struct fragmhdr *) pkt_pull(pkt, sizeof(*fragm_ops));
  31         if (fragm_ops == NULL)
  32                 return;
  33
  34         off_res_M = ntohs(fragm_ops->h_fragm_off_res_M);
  35
  36         tprintf("\t [ Fragment ");
  37         tprintf("NextHdr (%u), ", fragm_ops->h_fragm_next_header);
  38         tprintf("Reserved (%u), ", fragm_ops->h_fragm_reserved);
  39         tprintf("Offset (%u), ", off_res_M >> 3);
  40         tprintf("Res (%u), ", (off_res_M >> 1) & 0x3);
  41         tprintf("M flag (%u), ", off_res_M & 0x1);
  42         tprintf("Identification (%u)",
  43                 ntohl(fragm_ops->h_fragm_identification));
  44         tprintf(" ]\n");
  45
  46         pkt_set_dissector(pkt, &eth_lay3, fragm_ops->h_fragm_next_header);
  47 }
  48
  49 static void fragm_less(struct pkt_buff *pkt)
  50 {
  51         uint16_t off_res_M;
  52         struct fragmhdr *fragm_ops;
  53
  54         fragm_ops = (struct fragmhdr *) pkt_pull(pkt, sizeof(*fragm_ops));
  55         if (fragm_ops == NULL)
  56                 return;
  57
  58         off_res_M = ntohs(fragm_ops->h_fragm_off_res_M);
  59
  60         tprintf(" FragmOffs %u", off_res_M >> 3);
  61
  62         pkt_set_dissector(pkt, &eth_lay3, fragm_ops->h_fragm_next_header);
  63 }
  64
  65 struct protocol ipv6_fragm_ops = {
  66         .key = 0x2C,
  67         .print_full = fragm,
  68         .print_less = fragm_less,
  69 };