proto_icmpv4.c

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