proto_arp.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 <stdint.h>
   8 #include <netinet/in.h>    /* for ntohs() */
   9
  10 #include "proto.h"
  11 #include "protos.h"
  12 #include "dissector_eth.h"
  13 #include "pkt_buff.h"
  14 #include "built_in.h"
  15
  16 struct arphdr {
  17         uint16_t ar_hrd;   /* format of hardware address */
  18         uint16_t ar_pro;   /* format of protocol address */
  19         uint8_t ar_hln;    /* length of hardware address */
  20         uint8_t ar_pln;    /* length of protocol address */
  21         uint16_t ar_op;    /* ARP opcode (command)       */
  22         uint8_t ar_sha[6]; /* sender hardware address    */
  23         uint8_t ar_sip[4]; /* sender IP address          */
  24         uint8_t ar_tha[6]; /* target hardware address    */
  25         uint8_t ar_tip[4]; /* target IP address          */
  26 } __packed;
  27
  28 #define ARPHRD_ETHER    1
  29 #define ARPHRD_IEEE802  6
  30 #define ARPHRD_ARCNET   7
  31 #define ARPHRD_ATM      16
  32 #define ARPHRD_ATM2     19
  33 #define ARPHRD_SERIAL   20
  34 #define ARPHRD_ATM3     21
  35 #define ARPHRD_IEEE1394 24
  36
  37 #define ARPOP_REQUEST   1  /* ARP request                */
  38 #define ARPOP_REPLY     2  /* ARP reply                  */
  39 #define ARPOP_RREQUEST  3  /* RARP request               */
  40 #define ARPOP_RREPLY    4  /* RARP reply                 */
  41 #define ARPOP_InREQUEST 8  /* InARP request              */
  42 #define ARPOP_InREPLY   9  /* InARP reply                */
  43 #define ARPOP_NAK       10 /* (ATM)ARP NAK               */
  44
  45 static void arp(struct pkt_buff *pkt)
  46 {
  47         char *hrd;
  48         char *pro;
  49         char *opcode;
  50         struct arphdr *arp = (struct arphdr *) pkt_pull(pkt, sizeof(*arp));
  51
  52         if (arp == NULL)
  53                 return;
  54
  55         switch (ntohs(arp->ar_hrd)) {
  56         case ARPHRD_ETHER:
  57                 hrd = "Ethernet";
  58                 break;
  59         case ARPHRD_IEEE802:
  60                 hrd = "IEEE 802";
  61                 break;
  62         case ARPHRD_ARCNET:
  63                 hrd = "ARCNET";
  64                 break;
  65         case ARPHRD_ATM:
  66         case ARPHRD_ATM2:
  67         case ARPHRD_ATM3:
  68                 hrd = "ATM";
  69                 break;
  70         case ARPHRD_SERIAL:
  71                 hrd = "Serial Line";
  72                 break;
  73         case ARPHRD_IEEE1394:
  74                 hrd = "IEEE 1394.1995";
  75                 break;
  76         default:
  77                 hrd = "Unknown";
  78                 break;
  79         }
  80
  81         pro = lookup_ether_type(ntohs(arp->ar_pro));
  82         if (pro == NULL)
  83                 pro = "Unknown";
  84
  85         switch (ntohs(arp->ar_op)) {
  86         case ARPOP_REQUEST:
  87                 opcode = "ARP request";
  88                 break;
  89         case ARPOP_REPLY:
  90                 opcode = "ARP reply";
  91                 break;
  92         case ARPOP_RREQUEST:
  93                 opcode = "RARP request";
  94                 break;
  95         case ARPOP_RREPLY:
  96                 opcode = "RARP reply";
  97                 break;
  98         case ARPOP_InREQUEST:
  99                 opcode = "InARP request";
 100                 break;
 101         case ARPOP_InREPLY:
 102                 opcode = "InARP reply";
 103                 break;
 104         case ARPOP_NAK:
 105                 opcode = "(ATM) ARP NAK";
 106                 break;
 107         default:
 108                 opcode = "Unknown";
 109                 break;
 110         };
 111
 112         tprintf(" [ ARP ");
 113         tprintf("Format HA (%u => %s), ", ntohs(arp->ar_hrd), hrd);
 114         tprintf("Format Proto (0x%.4x => %s), ", ntohs(arp->ar_pro), pro);
 115         tprintf("HA Len (%u), ", arp->ar_hln);
 116         tprintf("Proto Len (%u), ", arp->ar_pln);
 117         tprintf("Opcode (%u => %s)", ntohs(arp->ar_op), opcode);
 118         tprintf(" ]\n");
 119 }
 120
 121 static void arp_less(struct pkt_buff *pkt)
 122 {
 123         char *opcode = NULL;
 124         struct arphdr *arp = (struct arphdr *) pkt_pull(pkt, sizeof(*arp));
 125
 126         if (arp == NULL)
 127                 return;
 128
 129         switch (ntohs(arp->ar_op)) {
 130         case ARPOP_REQUEST:
 131                 opcode = "ARP request";
 132                 break;
 133         case ARPOP_REPLY:
 134                 opcode = "ARP reply";
 135                 break;
 136         case ARPOP_RREQUEST:
 137                 opcode = "RARP request";
 138                 break;
 139         case ARPOP_RREPLY:
 140                 opcode = "RARP reply";
 141                 break;
 142         case ARPOP_InREQUEST:
 143                 opcode = "InARP request";
 144                 break;
 145         case ARPOP_InREPLY:
 146                 opcode = "InARP reply";
 147                 break;
 148         case ARPOP_NAK:
 149                 opcode = "(ATM) ARP NAK";
 150                 break;
 151         default:
 152                 opcode = "Unknown";
 153                 break;
 154         };
 155
 156         tprintf(" Op %s", opcode);
 157 }
 158
 159 struct protocol arp_ops = {
 160         .key = 0x0806,
 161         .print_full = arp,
 162         .print_less = arp_less,
 163 };