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 "protos.h"
  15 #include "dissector_eth.h"
  16 #include "built_in.h"
  17 #include "pkt_buff.h"
  18
  19 struct fragmhdr {
  20         uint8_t h_fragm_next_header;
  21         uint8_t h_fragm_reserved;
  22         uint16_t h_fragm_off_res_M;
  23         uint32_t h_fragm_identification;
  24 } __packed;
  25
  26 static void fragm(struct pkt_buff *pkt)
  27 {
  28         uint16_t off_res_M;
  29         struct fragmhdr *fragm_ops;
  30
  31         fragm_ops = (struct fragmhdr *) pkt_pull(pkt, sizeof(*fragm_ops));
  32         if (fragm_ops == NULL)
  33                 return;
  34
  35         off_res_M = ntohs(fragm_ops->h_fragm_off_res_M);
  36
  37         tprintf("\t [ Fragment ");
  38         tprintf("NextHdr (%u), ", fragm_ops->h_fragm_next_header);
  39         tprintf("Reserved (%u), ", fragm_ops->h_fragm_reserved);
  40         tprintf("Offset (%u), ", off_res_M >> 3);
  41         tprintf("Res (%u), ", (off_res_M >> 1) & 0x3);
  42         tprintf("M flag (%u), ", off_res_M & 0x1);
  43         tprintf("Identification (%u)",
  44                 ntohl(fragm_ops->h_fragm_identification));
  45         tprintf(" ]\n");
  46
  47         pkt_set_proto(pkt, &eth_lay3, fragm_ops->h_fragm_next_header);
  48 }
  49
  50 static void fragm_less(struct pkt_buff *pkt)
  51 {
  52         uint16_t off_res_M;
  53         struct fragmhdr *fragm_ops;
  54
  55         fragm_ops = (struct fragmhdr *) pkt_pull(pkt, sizeof(*fragm_ops));
  56         if (fragm_ops == NULL)
  57                 return;
  58
  59         off_res_M = ntohs(fragm_ops->h_fragm_off_res_M);
  60
  61         tprintf(" FragmOffs %u", off_res_M >> 3);
  62
  63         pkt_set_proto(pkt, &eth_lay3, fragm_ops->h_fragm_next_header);
  64 }
  65
  66 struct protocol ipv6_fragm_ops = {
  67         .key = 0x2C,
  68         .print_full = fragm,
  69         .print_less = fragm_less,
  70 };