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