proto_ipv6_hop_by_hop.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 Hop-By-Hop 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 hop_by_hophdr {
  20         uint8_t h_next_header;
  21         uint8_t hdr_len;
  22 } __packed;
  23
  24 static void dissect_opt_hop(struct pkt_buff *pkt __maybe_unused,
  25                             ssize_t *opt_len)
  26 {
  27         /* Have to been upgraded.
  28          * http://tools.ietf.org/html/rfc2460#section-4.2
  29          * Look also for proto_ipv6_dest_opts.h, it needs
  30          * dissect_opt(), too.
  31          */
  32         if (*opt_len)
  33                 tprintf(", Option(s) recognized ");
  34
  35         /* If adding dissector reduce opt_len for each using of pkt_pull
  36          * to the same size.
  37          */
  38 }
  39
  40 static void hop_by_hop(struct pkt_buff *pkt)
  41 {
  42         uint16_t hdr_ext_len;
  43         ssize_t opt_len;
  44         struct hop_by_hophdr *hop_ops;
  45
  46         hop_ops = (struct hop_by_hophdr *) pkt_pull(pkt, sizeof(*hop_ops));
  47         if (hop_ops == NULL)
  48                 return;
  49
  50         /* Total Header Length in Bytes */
  51         hdr_ext_len = (hop_ops->hdr_len + 1) * 8;
  52         /* Options length in Bytes */
  53         opt_len = hdr_ext_len - sizeof(*hop_ops);
  54
  55         tprintf("\t [ Hop-by-Hop Options ");
  56         tprintf("NextHdr (%u), ", hop_ops->h_next_header);
  57         if (opt_len > pkt_len(pkt) || opt_len < 0){
  58                 tprintf("HdrExtLen (%u, %u Bytes, %s)", hop_ops->hdr_len,
  59                       hdr_ext_len, colorize_start_full(black, red)
  60                       "invalid" colorize_end());
  61                       return;
  62         }
  63         tprintf("HdrExtLen (%u, %u Bytes)", hop_ops->hdr_len,
  64                 hdr_ext_len);
  65
  66         dissect_opt_hop(pkt, &opt_len);
  67
  68         tprintf(" ]\n");
  69
  70         pkt_pull(pkt, opt_len);
  71         pkt_set_proto(pkt, &eth_lay3, hop_ops->h_next_header);
  72 }
  73
  74 static void hop_by_hop_less(struct pkt_buff *pkt)
  75 {
  76         uint16_t hdr_ext_len;
  77         ssize_t opt_len;
  78         struct hop_by_hophdr *hop_ops;
  79
  80         hop_ops = (struct hop_by_hophdr *) pkt_pull(pkt, sizeof(*hop_ops));
  81         if (hop_ops == NULL)
  82                 return;
  83
  84         /* Total Header Length in Bytes */
  85         hdr_ext_len = (hop_ops->hdr_len + 1) * 8;
  86         /* Options length in Bytes */
  87         opt_len = hdr_ext_len - sizeof(*hop_ops);
  88         if (opt_len > pkt_len(pkt) || opt_len < 0)
  89                 return;
  90
  91         tprintf(" Hop Ops");
  92
  93         pkt_pull(pkt, opt_len);
  94         pkt_set_proto(pkt, &eth_lay3, hop_ops->h_next_header);
  95 }
  96
  97 struct protocol ipv6_hop_by_hop_ops = {
  98         .key = 0x0,
  99         .print_full = hop_by_hop,
 100         .print_less = hop_by_hop_less,
 101 };