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 "pkt_buff.h"
  15 #include "built_in.h"
  16
  17 struct icmphdr {
  18         uint8_t type;
  19         uint8_t code;
  20         uint16_t checksum;
  21         union {
  22                 struct {
  23                         uint16_t id;
  24                         uint16_t sequence;
  25                 } echo;
  26                 uint32_t gateway;
  27                 struct {
  28                         uint16_t ____unused;
  29                         uint16_t mtu;
  30                 } frag;
  31         } un;
  32 } __packed;
  33
  34 static void icmp(struct pkt_buff *pkt)
  35 {
  36         struct icmphdr *icmp = (struct icmphdr *) pkt_pull(pkt, sizeof(*icmp));
  37         uint16_t csum;
  38
  39         if (icmp == NULL)
  40                 return;
  41
  42         csum = calc_csum(icmp, pkt_len(pkt) + sizeof(*icmp), 0);
  43
  44         tprintf(" [ ICMP ");
  45         tprintf("Type (%u), ", icmp->type);
  46         tprintf("Code (%u), ", icmp->code);
  47         tprintf("CSum (0x%.4x) is %s", ntohs(icmp->checksum),
  48                 csum ? colorize_start_full(black, red) "bogus (!)"
  49                        colorize_end() : "ok");
  50         tprintf(" ]\n");
  51 }
  52
  53 static void icmp_less(struct pkt_buff *pkt)
  54 {
  55         struct icmphdr *icmp = (struct icmphdr *) pkt_pull(pkt, sizeof(*icmp));
  56
  57         if (icmp == NULL)
  58                 return;
  59
  60         tprintf(" Type %u Code %u", icmp->type, icmp->code);
  61 }
  62
  63 struct protocol icmpv4_ops = {
  64         .key = 0x01,
  65         .print_full = icmp,
  66         .print_less = icmp_less,
  67 };