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 "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
  39         if (icmp == NULL)
  40                 return;
  41
  42         tprintf(" [ ICMP ");
  43         tprintf("Type (%u), ", icmp->type);
  44         tprintf("Code (%u), ", icmp->code);
  45         tprintf("CSum (0x%.4x)", ntohs(icmp->checksum));
  46         tprintf(" ]\n");
  47 }
  48
  49 static void icmp_less(struct pkt_buff *pkt)
  50 {
  51         struct icmphdr *icmp = (struct icmphdr *) pkt_pull(pkt, sizeof(*icmp));
  52
  53         if (icmp == NULL)
  54                 return;
  55
  56         tprintf(" Type %u Code %u", icmp->type, icmp->code);
  57 }
  58
  59 struct protocol icmpv4_ops = {
  60         .key = 0x01,
  61         .print_full = icmp,
  62         .print_less = icmp_less,
  63 };