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/* ARP */
#include <stdio.h>
#include <inttypes.h>
#include <dlfcn.h>
#include "libpacketdump.h"
#include <sys/socket.h>
#ifndef WIN32
#include <netinet/in_systm.h>
#endif
#include <netinet/in.h>
#include <netinet/ip.h>
#include <net/if_arp.h>
#include <arpa/inet.h>
#include <string.h>
/*
* Converts an ARP hardware address to a printable string.
* Takes an ARP header structure and a pointer to the start
* of the hardware address in the structure that we should
* attempt to decode.
*/
static char *format_hrd(const struct arphdr *arp, const char *hrd) {
static char buffer[1024] = {0,};
int i;
if (!hrd) {
strncpy(buffer, "(Truncated)", sizeof(buffer));
return buffer;
}
switch(ntohs(arp->ar_hrd)) {
case ARPHRD_ETHER:
trace_ether_ntoa((const unsigned char *)hrd, buffer);
break;
default:
for (i=0;i<arp->ar_hln;i++) {
snprintf(buffer,sizeof(buffer),"%s %02x",
buffer,(unsigned char)hrd[i]);
}
break;
}
return buffer;
}
/*
* Converts an ARP protocol address to a printable string.
* Takes an ARP header structure and a pointer to the start
* of the protocol address in the structure that we should
* attempt to decode.
*/
static char *format_pro(const struct arphdr *arp, const char *pro) {
static char buffer[1024] = {0,};
int i;
if (!pro) {
strncpy(buffer, "(Truncated)", sizeof(buffer));
return buffer;
}
switch(ntohs(arp->ar_pro)) {
case 0x0800:
snprintf(buffer,sizeof(buffer),"%s",
inet_ntoa(*(struct in_addr*)pro));
break;
default:
strncat(buffer," (",sizeof(buffer));
for (i=0;i<arp->ar_pln;i++) {
snprintf(buffer,sizeof(buffer),"%s %02x",
buffer,(unsigned char)pro[i]);
}
strncat(buffer,")",sizeof(buffer));
break;
}
return buffer;
}
DLLEXPORT void decode(int link_type UNUSED,const char *packet,unsigned len)
{
struct arphdr *arp = (struct arphdr*)packet;
const char *source_hrd = NULL;
const char *source_pro = NULL;
const char *dest_hrd = NULL;
const char *dest_pro = NULL;
if (len < sizeof(struct arphdr)) {
printf(" ARP: (Truncated)\n");
return;
}
if (len >= sizeof(struct arphdr) + arp->ar_hln)
source_hrd = packet + sizeof(struct arphdr);
if (len >= sizeof(struct arphdr) + arp->ar_hln + arp->ar_pln)
source_pro = source_hrd + arp->ar_hln;
if (len >= sizeof(struct arphdr) + arp->ar_hln * 2 + arp->ar_pln)
dest_hrd = source_pro + arp->ar_pln;
if (len >= sizeof(struct arphdr) + arp->ar_hln * 2 + arp->ar_pln * 2)
dest_pro = dest_hrd + arp->ar_hln;
switch(ntohs(arp->ar_op)) {
case ARPOP_REQUEST:
printf(" ARP: who-has %s", format_pro(arp, dest_pro));
printf(" tell %s (%s)\n", format_pro(arp, source_pro),
format_hrd(arp, source_hrd));
break;
case ARPOP_REPLY:
printf(" ARP: reply %s", format_pro(arp, source_pro));
printf(" is-at %s\n", format_hrd(arp, source_hrd));
break;
default:
printf(" ARP: Unknown opcode (%i) from %s to %s\n",
ntohs(arp->ar_op),
format_pro(arp, source_pro),
format_pro(arp, dest_pro));
break;
}
return;
}
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