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 "dissector_eth.h"
  15 #include "built_in.h"
  16 #include "pkt_buff.h"
  17
  18 struct hop_by_hophdr {
  19         uint8_t h_next_header;
  20         uint8_t hdr_len;
  21 } __packed;
  22
  23 static void dissect_opt_hop(struct pkt_buff *pkt __maybe_unused,
  24                             ssize_t *opt_len)
  25 {
  26         /* Have to been upgraded.
  27          * http://tools.ietf.org/html/rfc2460#section-4.2
  28          * Look also for proto_ipv6_dest_opts.h, it needs
  29          * dissect_opt(), too.
  30          */
  31         if (*opt_len)
  32                 tprintf(", Option(s) recognized ");
  33
  34         /* If adding dissector reduce opt_len for each using of pkt_pull
  35          * to the same size.
  36          */
  37 }
  38
  39 static void hop_by_hop(struct pkt_buff *pkt)
  40 {
  41         uint16_t hdr_ext_len;
  42         ssize_t opt_len;
  43         struct hop_by_hophdr *hop_ops;
  44
  45         hop_ops = (struct hop_by_hophdr *) pkt_pull(pkt, sizeof(*hop_ops));
  46         if (hop_ops == NULL)
  47                 return;
  48
  49         /* Total Header Length in Bytes */
  50         hdr_ext_len = (hop_ops->hdr_len + 1) * 8;
  51         /* Options length in Bytes */
  52         opt_len = hdr_ext_len - sizeof(*hop_ops);
  53
  54         tprintf("\t [ Hop-by-Hop Options ");
  55         tprintf("NextHdr (%u), ", hop_ops->h_next_header);
  56         if (opt_len > pkt_len(pkt) || opt_len < 0){
  57                 tprintf("HdrExtLen (%u, %u Bytes, %s)", hop_ops->hdr_len,
  58                       hdr_ext_len, colorize_start_full(black, red)
  59                       "invalid" colorize_end());
  60                       return;
  61         }
  62         tprintf("HdrExtLen (%u, %u Bytes)", hop_ops->hdr_len,
  63                 hdr_ext_len);
  64
  65         dissect_opt_hop(pkt, &opt_len);
  66
  67         tprintf(" ]\n");
  68
  69         pkt_pull(pkt, opt_len);
  70         pkt_set_proto(pkt, &eth_lay3, hop_ops->h_next_header);
  71 }
  72
  73 static void hop_by_hop_less(struct pkt_buff *pkt)
  74 {
  75         uint16_t hdr_ext_len;
  76         ssize_t opt_len;
  77         struct hop_by_hophdr *hop_ops;
  78
  79         hop_ops = (struct hop_by_hophdr *) pkt_pull(pkt, sizeof(*hop_ops));
  80         if (hop_ops == NULL)
  81                 return;
  82
  83         /* Total Header Length in Bytes */
  84         hdr_ext_len = (hop_ops->hdr_len + 1) * 8;
  85         /* Options length in Bytes */
  86         opt_len = hdr_ext_len - sizeof(*hop_ops);
  87         if (opt_len > pkt_len(pkt) || opt_len < 0)
  88                 return;
  89
  90         tprintf(" Hop Ops");
  91
  92         pkt_pull(pkt, opt_len);
  93         pkt_set_proto(pkt, &eth_lay3, hop_ops->h_next_header);
  94 }
  95
  96 struct protocol ipv6_hop_by_hop_ops = {
  97         .key = 0x0,
  98         .print_full = hop_by_hop,
  99         .print_less = hop_by_hop_less,
 100 };