proto_icmpv4.c

   1 /*
   2  * netsniff-ng - the packet sniffing beast
   3  * By Daniel Borkmann <daniel@netsniff-ng.org>
   4  * Copyright 2009, 2010 Daniel Borkmann.
   5  * Subject to the GPL, version 2.
   6  */
   7
   8 #include <stdio.h>
   9 #include <stdint.h>
  10 #include <netinet/in.h>    /* for ntohs() */
  11
  12 #include "proto.h"
  13 #include "protos.h"
  14 #include "csum.h"
  15 #include "dissector_eth.h"
  16 #include "pkt_buff.h"
  17 #include "built_in.h"
  18
  19 struct icmphdr {
  20         uint8_t type;
  21         uint8_t code;
  22         uint16_t checksum;
  23         union {
  24                 struct {
  25                         uint16_t id;
  26                         uint16_t sequence;
  27                 } echo;
  28                 uint32_t gateway;
  29                 struct {
  30                         uint16_t ____unused;
  31                         uint16_t mtu;
  32                 } frag;
  33         } un;
  34 } __packed;
  35
  36 static void icmp(struct pkt_buff *pkt)
  37 {
  38         struct icmphdr *icmp = (struct icmphdr *) pkt_pull(pkt, sizeof(*icmp));
  39         uint16_t csum;
  40
  41         if (icmp == NULL)
  42                 return;
  43
  44         csum = calc_csum(icmp, pkt_len(pkt) + sizeof(*icmp), 0);
  45
  46         tprintf(" [ ICMP ");
  47         tprintf("Type (%u), ", icmp->type);
  48         tprintf("Code (%u), ", icmp->code);
  49         tprintf("CSum (0x%.4x) is %s", ntohs(icmp->checksum),
  50                 csum ? colorize_start_full(black, red) "bogus (!)"
  51                        colorize_end() : "ok");
  52         tprintf(" ]\n");
  53 }
  54
  55 static void icmp_less(struct pkt_buff *pkt)
  56 {
  57         struct icmphdr *icmp = (struct icmphdr *) pkt_pull(pkt, sizeof(*icmp));
  58
  59         if (icmp == NULL)
  60                 return;
  61
  62         tprintf(" Type %u Code %u", icmp->type, icmp->code);
  63 }
  64
  65 struct protocol icmpv4_ops = {
  66         .key = 0x01,
  67         .print_full = icmp,
  68         .print_less = icmp_less,
  69 };