/*
* $Id: dhcp_discover.c,v 1.3 2004/01/03 20:31:01 mike Exp $
*
* libnet 1.1
* Build a DHCP discover packet
* To view: /usr/sbin/tcpdump -vvvvven -s 4096 'port 67 or port 68'
*
* Copyright (c) 1998 - 2004 Mike D. Schiffman <mike@infonexus.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
#if (HAVE_CONFIG_H)
#include "../include/config.h"
#endif
#include "./libnet_test.h"
#ifdef __WIN32__
#include "../include/win32/getopt.h"
#endif
void
usage(char *prog)
{
fprintf(stderr, "Usage: %s interface\n", prog);
exit(1);
}
int
main(int argc, char *argv[])
{
char *intf;
u_long src_ip, options_len, orig_len;
int i;
libnet_t *l;
libnet_ptag_t t;
libnet_ptag_t ip;
libnet_ptag_t udp;
libnet_ptag_t dhcp;
struct libnet_ether_addr *ethaddr;
struct libnet_stats ls;
char errbuf[LIBNET_ERRBUF_SIZE];
u_char options_req[] = { LIBNET_DHCP_SUBNETMASK,
LIBNET_DHCP_BROADCASTADDR, LIBNET_DHCP_TIMEOFFSET,
LIBNET_DHCP_ROUTER, LIBNET_DHCP_DOMAINNAME,
LIBNET_DHCP_DNS, LIBNET_DHCP_HOSTNAME };
u_char *options;
u_char enet_dst[6] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
u_char *tmp;
if (argc != 2)
{
usage(argv[0]);
}
intf = argv[1];
l = libnet_init(LIBNET_LINK, intf, errbuf);
if (!l)
{
fprintf(stderr, "libnet_init: %s", errbuf);
exit(EXIT_FAILURE);
}
else
{
src_ip = libnet_get_ipaddr4(l);;
if ((ethaddr = libnet_get_hwaddr(l)) == NULL)
{
fprintf(stderr, "libnet_get_hwaddr: %s\n", libnet_geterror(l));
exit(EXIT_FAILURE);
}
printf("ip addr : %s\n", libnet_addr2name4(src_ip,
LIBNET_DONT_RESOLVE));
printf("eth addr : ");
for (i = 0; i < 6; i++)
{
printf("%2.2x", ethaddr->ether_addr_octet[i]);
if (i != 5)
{
printf(":");
}
}
printf("\n");
/* build options packet */
i = 0;
/* update total payload size */
options_len = 3;
/* we are a discover packet */
options = malloc(3);
options[i++] = LIBNET_DHCP_MESSAGETYPE; /* type */
options[i++] = 1; /* len */
options[i++] = LIBNET_DHCP_MSGDISCOVER; /* data */
orig_len = options_len;
/* update total payload size */
options_len += sizeof(options_req) + 2;
tmp = malloc(options_len);
memcpy(tmp, options, orig_len);
free(options);
options = tmp;
/* we are going to request some parameters */
options[i++] = LIBNET_DHCP_PARAMREQUEST; /* type */
options[i++] = sizeof(options_req); /* len */
memcpy(options + i, options_req, sizeof(options_req)); /* data */
i += sizeof(options_req);
/* if we have an ip already, let's request it. */
if (src_ip)
{
orig_len = options_len;
options_len += 2 + sizeof(src_ip);
tmp = malloc(options_len);
memcpy(tmp, options, orig_len);
free(options);
options = tmp;
options[i++] = LIBNET_DHCP_DISCOVERADDR; /* type */
options[i++] = sizeof(src_ip); /* len */
memcpy(options + i, (char *)&src_ip, sizeof(src_ip)); /* data */
i += sizeof(src_ip);
}
/* end our options packet */
orig_len = options_len;
options_len += 1;
tmp = malloc(options_len);
memcpy(tmp, options, orig_len);
free(options);
options = tmp;
options[i++] = LIBNET_DHCP_END;
/* make sure we are at least the minimum length, if not fill */
/* this could go in libnet, but we will leave it in the app for now */
if (options_len + LIBNET_DHCPV4_H < LIBNET_BOOTP_MIN_LEN)
{
orig_len = options_len;
options_len = LIBNET_BOOTP_MIN_LEN - LIBNET_DHCPV4_H;
tmp = malloc(options_len);
memcpy(tmp, options, orig_len);
free(options);
options = tmp;
memset(options + i, 0, options_len - i);
}
dhcp = libnet_build_dhcpv4(
LIBNET_DHCP_REQUEST, /* opcode */
1, /* hardware type */
6, /* hardware address length */
0, /* hop count */
0xdeadbeef, /* transaction id */
0, /* seconds since bootstrap */
0x8000, /* flags */
0, /* client ip */
0, /* your ip */
0, /* server ip */
0, /* gateway ip */
ethaddr->ether_addr_octet, /* client hardware addr */
NULL, /* server host name */
NULL, /* boot file */
options, /* dhcp options in payload */
options_len, /* length of options */
l, /* libnet context */
0); /* libnet ptag */
udp = libnet_build_udp(
68, /* source port */
67, /* destination port */
LIBNET_UDP_H + LIBNET_DHCPV4_H + options_len, /* packet size */
0, /* checksum */
NULL, /* payload */
0, /* payload size */
l, /* libnet context */
0); /* libnet ptag */
ip = libnet_build_ipv4(
LIBNET_IPV4_H + LIBNET_UDP_H + LIBNET_DHCPV4_H
+ options_len, /* length */
0x10, /* TOS */
0, /* IP ID */
0, /* IP Frag */
16, /* TTL */
IPPROTO_UDP, /* protocol */
0, /* checksum */
src_ip, /* src ip */
inet_addr("255.255.255.255"), /* destination ip */
NULL, /* payload */
0, /* payload size */
l, /* libnet context */
0); /* libnet ptag */
t = libnet_autobuild_ethernet(
enet_dst, /* ethernet destination */
ETHERTYPE_IP, /* protocol type */
l); /* libnet context */
if (libnet_write(l) == -1)
{
fprintf(stderr, " %s: libnet_write: %s\n", argv[0],
strerror(errno));
exit(EXIT_FAILURE);
}
libnet_stats(l, &ls);
fprintf(stderr, "Packets sent: %lld\n"
"Packet errors: %lld\n"
"Bytes written: %lld\n",
ls.packets_sent, ls.packet_errors, ls.bytes_written);
libnet_destroy(l);
free(options);
exit(0);
}
exit(0);
}