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/*
* The Network Discovery Tool.
* Copyright (C) 2005 Tadas Vilkeliskis aka vptr (vpointer@gmail.com)
*
* The Network Discovery Tool 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 2.1 of the License, or (at your option) any later version.
*
* This program 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 this program; if not, write to the Free
* Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
* 02111-1307 USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <netinet/ether.h>
#include <netinet/if_ether.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netpacket/packet.h>
#include <unistd.h>
#include <fcntl.h>
#include "netdt.h"
#include "defs.h"
#include "param.h"
#include "iface.h"
#include "network.h"
void arp_generate_packet(struct in_addr, struct in_addr, struct ether_addr, u_int8_t *);
int arp_init(int argc, char **argv)
{
PDEBUG("arp_init called\n");
extern struct param param;
struct in_addr sip, tip, netmask, tmp;
int sock_fd;
struct sockaddr_ll saddr_ll;
socklen_t sa_size = sizeof(struct sockaddr_ll);
struct ether_addr mac;
struct ether_arp *arp_header;
u_int8_t packet[sizeof(struct ether_header) + sizeof(struct ether_arp)];
//printf("%d\n", sizeof(packet)); exit(0);
/* ETH_ALEN, ARPHDR_ETHER, ETHERTYPE_ARP */
if ( (sock_fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ARP))) == -1) {
PDEBUG("ERROR: socket() failed\n");
fprintf(stderr, "Error: can't create socket\n");
exit(1);
}
if (fcntl(sock_fd, F_SETFL, O_NONBLOCK) == -1) {
PDEBUG("ERROR: fcntl() failed\n");
fprintf(stderr, "Error: can't make socket non-blocking\n");
close(sock_fd);
exit(1);
}
iface_init(sock_fd, param.iface);
if ( (saddr_ll.sll_ifindex = iface_get_index()) == -1) {
fprintf(stderr, "Error: no such device %s\n", param.iface);
close(sock_fd);
exit(1);
}
/*
XXX
po situ veiksmu reiketu atlikti
patikrinima ar yra teisingas IP adresas
*/
iface_get_ip(&sip);
iface_get_netmask(&netmask);
iface_get_mac(&mac);
saddr_ll.sll_family = PF_PACKET;
saddr_ll.sll_halen = ETH_ALEN;
memset(&saddr_ll.sll_addr, 0, ETH_ALEN);
net_calc_network(sip, netmask);
tip.s_addr = sip.s_addr & netmask.s_addr;
arp_header = (struct ether_arp*)(packet + sizeof(struct ether_header));
fprintf(stdout, "Discovering network with %s/%s\n\n", inet_ntoa(sip), ether_ntoa(&mac));
while ( (tip.s_addr = net_next_ip(tip)) != 0) {
//printf("%s\n", inet_ntoa(tip));
memset(packet, 0, sizeof(packet));
arp_generate_packet(sip, tip, mac, packet);
sendto(sock_fd, &packet, 42, 0, (struct sockaddr*)&saddr_ll, sizeof(struct sockaddr_ll));
usleep(param.packet_delay * 100);
if (recvfrom(sock_fd, &packet, 42, 0, (struct sockaddr*)&saddr_ll, &sa_size) == 42) {
if (arp_header->arp_op == htons(ARPOP_REPLY)) {
memcpy((void*)&tmp, (void*)&arp_header->arp_spa, 4);
fprintf(stdout, "%-15s %s\n", inet_ntoa(tmp),
ether_ntoa((struct ether_addr*)&arp_header->arp_sha));
}
}
}
return (0);
}
void arp_generate_packet(struct in_addr sip, struct in_addr tip, struct ether_addr smac, u_int8_t *packet)
{
struct ether_header *eth_header;
struct ether_arp *arp_header;
eth_header = (struct ether_header*)packet;
memset((void*)ð_header->ether_dhost, 0xff, ETH_ALEN); /* broadcast */
memcpy((void*)ð_header->ether_shost, (void*)&smac.ether_addr_octet, ETH_ALEN);
eth_header->ether_type = htons(ETHERTYPE_ARP);
arp_header = (struct ether_arp*)(packet + sizeof(struct ether_header));
arp_header->arp_hrd = htons(ARPHRD_ETHER);
arp_header->arp_pro = htons(ETHERTYPE_IP);
arp_header->arp_hln = ETH_ALEN;
arp_header->arp_pln = 4; /* reikia susiziureti ar nera kokios konstantos */
arp_header->arp_op = htons(ARPOP_REQUEST);
memcpy((void*)arp_header->arp_sha, (void*)&smac.ether_addr_octet, ETH_ALEN);
memcpy((void*)arp_header->arp_spa, (void*)&sip.s_addr, 4);
memcpy((void*)arp_header->arp_tpa, (void*)&tip.s_addr, 4);
}
void arp_usage(char *pname)
{
fprintf(stderr, "The Network Discovery Tool " PROGRAM_VERSION " by " PROGRAM_AUTHOR "\n"
"Usage: %s arp <options>\n"
"Options:\n"
" -i <if> Network interface\n"
" -t <time> Delay between packets\n"
" -h Help screen\n"
, pname);
exit(0);
}
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