dhcpc.c

该模块功能可以实现DHCP

/* dhcpc.c
 *
 * udhcp DHCP client
 *
 * Russ Dill <[e-mail]> July 2001
 *
 * This program 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 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
 
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/file.h>
#include <unistd.h>
#include <getopt.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <signal.h>
#include <time.h>
#include <string.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <errno.h>

#include "dhcpd.h"
#include "dhcpc.h"
#include "options.h"
#include "clientpacket.h"
#include "packet.h"
#include "script.h"
#include "socket.h"
#include "debug.h"
#include "pidfile.h"
#include "get_time.h"

static int state;
static unsigned long requested_ip; /* = 0 */
static unsigned long server_addr;
static unsigned long timeout;
static int packet_num; /* = 0 */
static int fd;
static int signal_pipe[2];

#define LISTEN_NONE 0
#define LISTEN_KERNEL 1
#define LISTEN_RAW 2
static int listen_mode;

#define DEFAULT_SCRIPT	"/usr/share/udhcpc/default.script"

struct client_config_t client_config = {
	/* Default options. */
	abort_if_no_lease: 0,
	foreground: 0,
	quit_after_lease: 0,
	background_if_no_lease: 0,
	interface: "eth0",
	pidfile: NULL,
	script: DEFAULT_SCRIPT,
	clientid: NULL,
	hostname: NULL,
	ifindex: 0,
	arp: "\0\0\0\0\0\0",		/* appease gcc-3.0 */
};

#ifndef BB_VER
static void show_usage(void)
{
	printf(
"Usage: udhcpc [OPTIONS]\n\n"
"  -c, --clientid=CLIENTID         Client identifier\n"
"  -H, --hostname=HOSTNAME         Client hostname\n"
"  -h                              Alias for -H\n"
"  -f, --foreground                Do not fork after getting lease\n"
"  -b, --background                Fork to background if lease cannot be\n"
"                                  immediately negotiated.\n"
"  -i, --interface=INTERFACE       Interface to use (default: eth0)\n"
"  -n, --now                       Exit with failure if lease cannot be\n"
"                                  immediately negotiated.\n"
"  -p, --pidfile=file              Store process ID of daemon in file\n"
"  -q, --quit                      Quit after obtaining lease\n"
"  -r, --request=IP                IP address to request (default: none)\n"
"  -s, --script=file               Run file at dhcp events (default:\n"
"                                  " DEFAULT_SCRIPT ")\n"
"  -v, --version                   Display version\n"
	);
	exit(0);
}
#endif


/* just a little helper */
static void change_mode(int new_mode)
{
	DEBUG(LOG_INFO, "entering %s listen mode",
		new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
	close(fd);
	fd = -1;
	listen_mode = new_mode;
}


/* perform a renew */
static void perform_renew(void)
{
	LOG(LOG_INFO, "Performing a DHCP renew");
	switch (state) {
	case BOUND:
		change_mode(LISTEN_KERNEL);
	case RENEWING:
	case REBINDING:
		state = RENEW_REQUESTED;
		break;
	case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
		run_script(NULL, "deconfig");
	case REQUESTING:
	case RELEASED:
		change_mode(LISTEN_RAW);
		state = INIT_SELECTING;
		break;
	case INIT_SELECTING:
	}

	/* start things over */
	packet_num = 0;

	/* Kill any timeouts because the user wants this to hurry along */
	timeout = 0;
}


/* perform a release */
static void perform_release(void)
{
	char buffer[16];
	struct in_addr temp_addr;

	/* send release packet */
	if (state == BOUND || state == RENEWING || state == REBINDING) {
		temp_addr.s_addr = server_addr;
		sprintf(buffer, "%s", inet_ntoa(temp_addr));
		temp_addr.s_addr = requested_ip;
		LOG(LOG_INFO, "Unicasting a release of %s to %s", 
				inet_ntoa(temp_addr), buffer);
		send_release(server_addr, requested_ip); /* unicast */
		run_script(NULL, "deconfig");
	}
	LOG(LOG_INFO, "Entering released state");

	change_mode(LISTEN_NONE);
	state = RELEASED;
	timeout = 0x7fffffff;
}


/* Exit and cleanup */
static void exit_client(int retval)
{
	pidfile_delete(client_config.pidfile);
	CLOSE_LOG();
	exit(retval);
}


/* Signal handler */
static void signal_handler(int sig)
{
	if (write(signal_pipe[1], &sig, sizeof(sig)) < 0) {
		LOG(LOG_ERR, "Could not send signal: %s",
			strerror(errno));
	}
}


static void background(void)
{
	int pid_fd;

	pid_fd = pidfile_acquire(client_config.pidfile); /* hold lock during fork. */
	while (pid_fd >= 0 && pid_fd < 3) pid_fd = dup(pid_fd); /* don't let daemon close it */
	if (daemon(0, 0) == -1) {
		perror("fork");
		exit_client(1);
	}
	client_config.foreground = 1; /* Do not fork again. */
	pidfile_write_release(pid_fd);
}


#ifdef COMBINED_BINARY
int udhcpc_main(int argc, char *argv[])
#else
int main(int argc, char *argv[])
#endif
{
	unsigned char *temp, *message;
	unsigned long t1 = 0, t2 = 0, xid = 0;
	unsigned long start = 0, lease;
	fd_set rfds;
	int retval;
	struct timeval tv;
	int c, len;
	struct dhcpMessage packet;
	struct in_addr temp_addr;
	int pid_fd;
	time_t now;
	int max_fd;
	int sig;

	static struct option arg_options[] = {
		{"clientid",	required_argument,	0, 'c'},
		{"foreground",	no_argument,		0, 'f'},
		{"background",	no_argument,		0, 'b'},
		{"hostname",	required_argument,	0, 'H'},
		{"hostname",    required_argument,      0, 'h'},
		{"interface",	required_argument,	0, 'i'},
		{"now", 	no_argument,		0, 'n'},
		{"pidfile",	required_argument,	0, 'p'},
		{"quit",	no_argument,		0, 'q'},
		{"request",	required_argument,	0, 'r'},
		{"script",	required_argument,	0, 's'},
		{"version",	no_argument,		0, 'v'},
		{"help",	no_argument,		0, '?'},
		{0, 0, 0, 0}
	};

	/* get options */
	while (1) {
		int option_index = 0;
		c = getopt_long(argc, argv, "c:fbH:h:i:np:qr:s:v", arg_options, &option_index);
		if (c == -1) break;
		
		switch (c) {
		case 'c':
			len = strlen(optarg) > 255 ? 255 : strlen(optarg);
			if (client_config.clientid) free(client_config.clientid);
			client_config.clientid = xmalloc(len + 2);
			client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
			client_config.clientid[OPT_LEN] = len;
			client_config.clientid[OPT_DATA] = '\0';
			strncpy(client_config.clientid + OPT_DATA, optarg, len);
			break;
		case 'f':
			client_config.foreground = 1;
			break;
		case 'b':
			client_config.background_if_no_lease = 1;
			break;
		case 'h':
		case 'H':
			len = strlen(optarg) > 255 ? 255 : strlen(optarg);
			if (client_config.hostname) free(client_config.hostname);
			client_config.hostname = xmalloc(len + 2);
			client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
			client_config.hostname[OPT_LEN] = len;
			strncpy(client_config.hostname + 2, optarg, len);
			break;
		case 'i':
			client_config.interface =  optarg;
			break;
		case 'n':
			client_config.abort_if_no_lease = 1;
			break;
		case 'p':
			client_config.pidfile = optarg;
			break;
		case 'q':
			client_config.quit_after_lease = 1;
			break;
		case 'r':
			requested_ip = inet_addr(optarg);
			break;