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arp.c
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arp.c
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/*
* This file is part of the dSploit.
*
* Copyleft of Simone Margaritelli aka evilsocket <evilsocket@gmail.com>
*
* dSploit is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* dSploit is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with dSploit. If not, see <http://www.gnu.org/licenses/>.
*/
#include "arp.h"
static inline int xdigit (char c)
{
unsigned d;
d = (unsigned)(c-'0');
if (d < 10) return (int)d;
d = (unsigned)(c-'a');
if (d < 6) return (int)(10+d);
d = (unsigned)(c-'A');
if (d < 6) return (int)(10+d);
return -1;
}
/*
* Convert Ethernet address in the standard hex-digits-and-colons to binary
* representation.
* Re-entrant version (GNU extensions)
*/
struct ether_addr *ether_aton_r (const char *asc, struct ether_addr * addr)
{
int i, val0, val1;
for (i = 0; i < ETHER_ADDR_LEN; ++i) {
val0 = xdigit(*asc);
asc++;
if (val0 < 0)
return NULL;
val1 = xdigit(*asc);
asc++;
if (val1 < 0)
return NULL;
addr->ether_addr_octet[i] = (unsigned char)((val0 << 4) + val1);
if (i < ETHER_ADDR_LEN - 1) {
if (*asc != ':')
return NULL;
asc++;
}
}
if (*asc != '\0')
return NULL;
return addr;
}
/*
* Convert Ethernet address in the standard hex-digits-and-colons to binary
* representation.
*/
struct ether_addr *ether_aton (const char *asc)
{
static struct ether_addr addr;
return ether_aton_r(asc, &addr);
}
int arp_lookup( in_addr_t address, struct ether_addr *ether, const char* ifname )
{
int num, type, flags;
FILE *fp = fopen( "/proc/net/arp", "r" );
char ip[128] = { 0x00 },
hwa[128] = { 0x00 },
mask[128] = { 0x00 },
line[128] = { 0x00 },
dev[128] = { 0x00 },
*ipaddress = inet_ntoa( *( struct in_addr *)&address );
if( !fp ) return -1;
/*
* Bypass header, read one line.
*/
fgets( line, sizeof(line), fp );
while( fgets( line, sizeof(line), fp ) )
{
/*
* All these strings can't overflow because fgets above reads limited amount of data
*/
num = sscanf( line, "%s 0x%x 0x%x %s %s %s\n", ip, &type, &flags, hwa, mask, dev );
if( num < 4 )
continue;
/*
* Not on the same interface, skip.
*/
if( strcmp( dev, ifname ) != 0 )
continue;
/*
* Unknown or broadcast address, skip.
*/
if( strcmp( hwa, "00:00:00:00:00:00" ) == 0 || strcmp( hwa, "FF:FF:FF:FF:FF:FF" ) == 0 || strcmp( hwa, "ff:ff:ff:ff:ff:ff" ) == 0 )
continue;
/*
* Found!
*/
if( strcmp( ip, ipaddress ) == 0 )
{
memcpy( ether, (void const *)ether_aton( hwa ), sizeof( struct ether_addr ) );
printf( "%s -> %s\n", ip, hwa );
fclose( fp );
return 0;
}
}
fclose( fp );
return -1;
}
int arp_send( libnet_t *pnet, int opcode, unsigned char *source_hardware, in_addr_t source_address, unsigned char *target_hardware, in_addr_t target_address )
{
int retval = -1;
if( source_hardware != NULL || ( source_hardware = (unsigned char *)libnet_get_hwaddr( pnet ) ) != NULL )
{
if( source_address != 0 || ( source_address = libnet_get_ipaddr4( pnet ) ) != -1 )
{
if( target_hardware == NULL )
target_hardware = BROADCAST_MAC_ADDR;
if( libnet_autobuild_arp( opcode, source_hardware, (unsigned char *)&source_address, target_hardware, (unsigned char *)&target_address, pnet ) != -1 )
{
if( libnet_build_ethernet( target_hardware, source_hardware, ETHERTYPE_ARP, NULL, 0, pnet, 0 ) != -1 )
{
retval = libnet_write( pnet );
if( retval == -1 )
printf( "error sending packet : %s\n", libnet_geterror( pnet ) );
else
printf
(
"sent arp %s from %s [ %x:%x:%x:%x:%x:%x ] to %s [ %x:%x:%x:%x:%x:%x ]\n",
opcode == ARPOP_REQUEST ? "request" : "reply",
inet_ntoa( *(struct in_addr *)&source_address ),
source_hardware[0], source_hardware[1], source_hardware[2], source_hardware[3], source_hardware[4], source_hardware[5],
inet_ntoa( *(struct in_addr *)&target_address ),
target_hardware[0], target_hardware[1], target_hardware[2], target_hardware[3], target_hardware[4], target_hardware[5]
);
libnet_clear_packet( pnet );
}
else
printf( "error building ethernet packet : %s\n", libnet_geterror( pnet ) );
}
else
printf( "error building arp packet : %s\n", libnet_geterror( pnet ) );
}
else
printf( "error obtaining source address : %s\n", libnet_geterror( pnet ) );
}
else
printf( "error obtaining source hardware address : %s\n", libnet_geterror( pnet ) );
return retval;
}