552 lines
15 KiB
C
552 lines
15 KiB
C
/* dhcpc.c
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*
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* udhcp DHCP client
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*
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* Russ Dill <Russ.Dill@asu.edu> July 2001
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <sys/time.h>
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#include <sys/file.h>
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#include <unistd.h>
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#include <getopt.h>
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#include <stdlib.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <signal.h>
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#include <time.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <net/if.h>
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#include <errno.h>
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#include "dhcpd.h"
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#include "dhcpc.h"
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#include "options.h"
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#include "clientpacket.h"
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#include "clientsocket.h"
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#include "script.h"
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#include "socket.h"
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#include "common.h"
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#include "signalpipe.h"
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static int state;
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static unsigned long requested_ip; /* = 0 */
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static unsigned long server_addr;
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static unsigned long timeout;
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static int packet_num; /* = 0 */
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static int fd = -1;
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#define LISTEN_NONE 0
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#define LISTEN_KERNEL 1
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#define LISTEN_RAW 2
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static int listen_mode;
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struct client_config_t client_config = {
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/* Default options. */
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.abort_if_no_lease = 0,
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.foreground = 0,
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.quit_after_lease = 0,
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.background_if_no_lease = 0,
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.interface = "eth0",
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.pidfile = NULL,
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.script = DEFAULT_SCRIPT,
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.clientid = NULL,
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.hostname = NULL,
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.fqdn = NULL,
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.ifindex = 0,
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.arp = "\0\0\0\0\0\0", /* appease gcc-3.0 */
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};
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#ifndef IN_BUSYBOX
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static void __attribute__ ((noreturn)) show_usage(void)
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{
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printf(
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"Usage: udhcpc [OPTIONS]\n\n"
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" -c, --clientid=CLIENTID Set client identifier\n"
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" -C, --clientid-none Suppress default client identifier\n"
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" -H, --hostname=HOSTNAME Client hostname\n"
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" -h Alias for -H\n"
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" -F, --fqdn=FQDN Client fully qualified domain name\n"
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" -f, --foreground Do not fork after getting lease\n"
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" -b, --background Fork to background if lease cannot be\n"
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" immediately negotiated.\n"
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" -i, --interface=INTERFACE Interface to use (default: eth0)\n"
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" -n, --now Exit with failure if lease cannot be\n"
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" immediately negotiated.\n"
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" -p, --pidfile=file Store process ID of daemon in file\n"
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" -q, --quit Quit after obtaining lease\n"
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" -r, --request=IP IP address to request (default: none)\n"
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" -s, --script=file Run file at dhcp events (default:\n"
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" " DEFAULT_SCRIPT ")\n"
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" -v, --version Display version\n"
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);
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exit(0);
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}
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#else
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#define show_usage bb_show_usage
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extern void show_usage(void) __attribute__ ((noreturn));
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#endif
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/* just a little helper */
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static void change_mode(int new_mode)
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{
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DEBUG(LOG_INFO, "entering %s listen mode",
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new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
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if (fd >= 0) close(fd);
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fd = -1;
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listen_mode = new_mode;
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}
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/* perform a renew */
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static void perform_renew(void)
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{
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LOG(LOG_INFO, "Performing a DHCP renew");
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switch (state) {
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case BOUND:
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change_mode(LISTEN_KERNEL);
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case RENEWING:
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case REBINDING:
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state = RENEW_REQUESTED;
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break;
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case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
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run_script(NULL, "deconfig");
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case REQUESTING:
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case RELEASED:
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change_mode(LISTEN_RAW);
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state = INIT_SELECTING;
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break;
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case INIT_SELECTING:
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break;
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}
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/* start things over */
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packet_num = 0;
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/* Kill any timeouts because the user wants this to hurry along */
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timeout = 0;
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}
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/* perform a release */
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static void perform_release(void)
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{
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char buffer[16];
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struct in_addr temp_addr;
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/* send release packet */
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if (state == BOUND || state == RENEWING || state == REBINDING) {
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temp_addr.s_addr = server_addr;
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sprintf(buffer, "%s", inet_ntoa(temp_addr));
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temp_addr.s_addr = requested_ip;
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LOG(LOG_INFO, "Unicasting a release of %s to %s",
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inet_ntoa(temp_addr), buffer);
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send_release(server_addr, requested_ip); /* unicast */
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run_script(NULL, "deconfig");
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}
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LOG(LOG_INFO, "Entering released state");
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change_mode(LISTEN_NONE);
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state = RELEASED;
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timeout = 0x7fffffff;
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}
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static void client_background(void)
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{
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background(client_config.pidfile);
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client_config.foreground = 1; /* Do not fork again. */
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client_config.background_if_no_lease = 0;
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}
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#ifdef COMBINED_BINARY
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int udhcpc_main(int argc, char *argv[])
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#else
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int main(int argc, char *argv[])
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#endif
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{
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uint8_t *temp, *message;
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unsigned long t1 = 0, t2 = 0, xid = 0;
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unsigned long start = 0, lease;
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fd_set rfds;
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int retval;
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struct timeval tv;
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int c, len;
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struct dhcpMessage packet;
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struct in_addr temp_addr;
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long now;
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int max_fd;
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int sig;
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int no_clientid = 0;
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static const struct option arg_options[] = {
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{"clientid", required_argument, 0, 'c'},
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{"clientid-none", no_argument, 0, 'C'},
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{"foreground", no_argument, 0, 'f'},
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{"background", no_argument, 0, 'b'},
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{"hostname", required_argument, 0, 'H'},
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{"hostname", required_argument, 0, 'h'},
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{"fqdn", required_argument, 0, 'F'},
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{"interface", required_argument, 0, 'i'},
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{"now", no_argument, 0, 'n'},
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{"pidfile", required_argument, 0, 'p'},
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{"quit", no_argument, 0, 'q'},
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{"request", required_argument, 0, 'r'},
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{"script", required_argument, 0, 's'},
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{"version", no_argument, 0, 'v'},
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{0, 0, 0, 0}
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};
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/* get options */
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while (1) {
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int option_index = 0;
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c = getopt_long(argc, argv, "c:CfbH:h:F:i:np:qr:s:v", arg_options, &option_index);
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if (c == -1) break;
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switch (c) {
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case 'c':
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if (no_clientid) show_usage();
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len = strlen(optarg) > 255 ? 255 : strlen(optarg);
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if (client_config.clientid) free(client_config.clientid);
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client_config.clientid = xmalloc(len + 2);
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client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
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client_config.clientid[OPT_LEN] = len;
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client_config.clientid[OPT_DATA] = '\0';
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strncpy(client_config.clientid + OPT_DATA, optarg, len);
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break;
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case 'C':
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if (client_config.clientid) show_usage();
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no_clientid = 1;
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break;
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case 'f':
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client_config.foreground = 1;
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break;
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case 'b':
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client_config.background_if_no_lease = 1;
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break;
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case 'h':
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case 'H':
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len = strlen(optarg) > 255 ? 255 : strlen(optarg);
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if (client_config.hostname) free(client_config.hostname);
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client_config.hostname = xmalloc(len + 2);
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client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
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client_config.hostname[OPT_LEN] = len;
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strncpy(client_config.hostname + 2, optarg, len);
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break;
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case 'F':
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len = strlen(optarg) > 255 ? 255 : strlen(optarg);
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if (client_config.fqdn) free(client_config.fqdn);
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client_config.fqdn = xmalloc(len + 5);
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client_config.fqdn[OPT_CODE] = DHCP_FQDN;
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client_config.fqdn[OPT_LEN] = len + 3;
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/* Flags: 0000NEOS
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S: 1 => Client requests Server to update A RR in DNS as well as PTR
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O: 1 => Server indicates to client that DNS has been updated regardless
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E: 1 => Name data is DNS format, i.e. <4>host<6>domain<4>com<0> not "host.domain.com"
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N: 1 => Client requests Server to not update DNS
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*/
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client_config.fqdn[OPT_LEN + 1] = 0x1;
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client_config.fqdn[OPT_LEN + 2] = 0;
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client_config.fqdn[OPT_LEN + 3] = 0;
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strncpy(client_config.fqdn + 5, optarg, len);
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break;
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case 'i':
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client_config.interface = optarg;
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break;
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case 'n':
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client_config.abort_if_no_lease = 1;
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break;
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case 'p':
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client_config.pidfile = optarg;
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break;
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case 'q':
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client_config.quit_after_lease = 1;
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break;
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case 'r':
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requested_ip = inet_addr(optarg);
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break;
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case 's':
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client_config.script = optarg;
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break;
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case 'v':
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printf("udhcpcd, version %s\n\n", VERSION);
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return 0;
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break;
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default:
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show_usage();
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}
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}
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/* Start the log, sanitize fd's, and write a pid file */
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start_log_and_pid("udhcpc", client_config.pidfile);
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if (read_interface(client_config.interface, &client_config.ifindex,
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NULL, client_config.arp) < 0)
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return 1;
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/* if not set, and not suppressed, setup the default client ID */
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if (!client_config.clientid && !no_clientid) {
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client_config.clientid = xmalloc(6 + 3);
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client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
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client_config.clientid[OPT_LEN] = 7;
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client_config.clientid[OPT_DATA] = 1;
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memcpy(client_config.clientid + 3, client_config.arp, 6);
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}
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/* setup the signal pipe */
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udhcp_sp_setup();
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state = INIT_SELECTING;
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run_script(NULL, "deconfig");
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change_mode(LISTEN_RAW);
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for (;;) {
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tv.tv_sec = timeout - uptime();
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tv.tv_usec = 0;
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if (listen_mode != LISTEN_NONE && fd < 0) {
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if (listen_mode == LISTEN_KERNEL)
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fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
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else
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fd = raw_socket(client_config.ifindex);
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if (fd < 0) {
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LOG(LOG_ERR, "FATAL: couldn't listen on socket, %m");
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return 0;
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}
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}
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max_fd = udhcp_sp_fd_set(&rfds, fd);
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if (tv.tv_sec > 0) {
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DEBUG(LOG_INFO, "Waiting on select...");
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retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
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} else retval = 0; /* If we already timed out, fall through */
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now = uptime();
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if (retval == 0) {
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/* timeout dropped to zero */
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switch (state) {
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case INIT_SELECTING:
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if (packet_num < 3) {
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if (packet_num == 0)
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xid = random_xid();
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/* send discover packet */
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send_discover(xid, requested_ip); /* broadcast */
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timeout = now + ((packet_num == 2) ? 4 : 2);
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packet_num++;
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} else {
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run_script(NULL, "leasefail");
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if (client_config.background_if_no_lease) {
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LOG(LOG_INFO, "No lease, forking to background.");
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client_background();
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} else if (client_config.abort_if_no_lease) {
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LOG(LOG_INFO, "No lease, failing.");
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return 1;
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}
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/* wait to try again */
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packet_num = 0;
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timeout = now + 60;
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}
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break;
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case RENEW_REQUESTED:
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case REQUESTING:
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if (packet_num < 3) {
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/* send request packet */
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if (state == RENEW_REQUESTED)
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send_renew(xid, server_addr, requested_ip); /* unicast */
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else send_selecting(xid, server_addr, requested_ip); /* broadcast */
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timeout = now + ((packet_num == 2) ? 10 : 2);
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packet_num++;
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} else {
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/* timed out, go back to init state */
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if (state == RENEW_REQUESTED) run_script(NULL, "deconfig");
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state = INIT_SELECTING;
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timeout = now;
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packet_num = 0;
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change_mode(LISTEN_RAW);
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}
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break;
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case BOUND:
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/* Lease is starting to run out, time to enter renewing state */
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state = RENEWING;
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change_mode(LISTEN_KERNEL);
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DEBUG(LOG_INFO, "Entering renew state");
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/* fall right through */
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case RENEWING:
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/* Either set a new T1, or enter REBINDING state */
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if ((t2 - t1) <= (lease / 14400 + 1)) {
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/* timed out, enter rebinding state */
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state = REBINDING;
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timeout = now + (t2 - t1);
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DEBUG(LOG_INFO, "Entering rebinding state");
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} else {
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/* send a request packet */
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send_renew(xid, server_addr, requested_ip); /* unicast */
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t1 = (t2 - t1) / 2 + t1;
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timeout = t1 + start;
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}
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break;
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case REBINDING:
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/* Either set a new T2, or enter INIT state */
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if ((lease - t2) <= (lease / 14400 + 1)) {
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/* timed out, enter init state */
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state = INIT_SELECTING;
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LOG(LOG_INFO, "Lease lost, entering init state");
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run_script(NULL, "deconfig");
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timeout = now;
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packet_num = 0;
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change_mode(LISTEN_RAW);
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} else {
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/* send a request packet */
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send_renew(xid, 0, requested_ip); /* broadcast */
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t2 = (lease - t2) / 2 + t2;
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timeout = t2 + start;
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}
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break;
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case RELEASED:
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/* yah, I know, *you* say it would never happen */
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timeout = 0x7fffffff;
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break;
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}
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} else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
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/* a packet is ready, read it */
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if (listen_mode == LISTEN_KERNEL)
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len = get_packet(&packet, fd);
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else len = get_raw_packet(&packet, fd);
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if (len == -1 && errno != EINTR) {
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DEBUG(LOG_INFO, "error on read, %m, reopening socket");
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change_mode(listen_mode); /* just close and reopen */
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}
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if (len < 0) continue;
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if (packet.xid != xid) {
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DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
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(unsigned long) packet.xid, xid);
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continue;
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}
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/* Ignore packets that aren't for us */
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if (memcmp(packet.chaddr, client_config.arp, 6)) {
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DEBUG(LOG_INFO, "packet does not have our chaddr -- ignoring");
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continue;
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}
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if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
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DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
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continue;
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}
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switch (state) {
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case INIT_SELECTING:
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/* Must be a DHCPOFFER to one of our xid's */
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if (*message == DHCPOFFER) {
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if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
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memcpy(&server_addr, temp, 4);
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xid = packet.xid;
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requested_ip = packet.yiaddr;
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/* enter requesting state */
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state = REQUESTING;
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timeout = now;
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packet_num = 0;
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} else {
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DEBUG(LOG_ERR, "No server ID in message");
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}
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}
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break;
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case RENEW_REQUESTED:
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case REQUESTING:
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case RENEWING:
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case REBINDING:
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if (*message == DHCPACK) {
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if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
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LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
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lease = 60 * 60;
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} else {
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memcpy(&lease, temp, 4);
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lease = ntohl(lease);
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}
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/* enter bound state */
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t1 = lease / 2;
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/* little fixed point for n * .875 */
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t2 = (lease * 0x7) >> 3;
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temp_addr.s_addr = packet.yiaddr;
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LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
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inet_ntoa(temp_addr), lease);
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start = now;
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timeout = t1 + start;
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requested_ip = packet.yiaddr;
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run_script(&packet,
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|
((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
|
|
|
|
state = BOUND;
|
|
change_mode(LISTEN_NONE);
|
|
if (client_config.quit_after_lease)
|
|
return 0;
|
|
if (!client_config.foreground)
|
|
client_background();
|
|
|
|
} else if (*message == DHCPNAK) {
|
|
/* return to init state */
|
|
LOG(LOG_INFO, "Received DHCP NAK");
|
|
run_script(&packet, "nak");
|
|
if (state != REQUESTING)
|
|
run_script(NULL, "deconfig");
|
|
state = INIT_SELECTING;
|
|
timeout = now;
|
|
requested_ip = 0;
|
|
packet_num = 0;
|
|
change_mode(LISTEN_RAW);
|
|
sleep(3); /* avoid excessive network traffic */
|
|
}
|
|
break;
|
|
/* case BOUND, RELEASED: - ignore all packets */
|
|
}
|
|
} else if (retval > 0 && (sig = udhcp_sp_read(&rfds))) {
|
|
switch (sig) {
|
|
case SIGUSR1:
|
|
perform_renew();
|
|
break;
|
|
case SIGUSR2:
|
|
perform_release();
|
|
break;
|
|
case SIGTERM:
|
|
LOG(LOG_INFO, "Received SIGTERM");
|
|
return 0;
|
|
}
|
|
} else if (retval == -1 && errno == EINTR) {
|
|
/* a signal was caught */
|
|
} else {
|
|
/* An error occured */
|
|
DEBUG(LOG_ERR, "Error on select");
|
|
}
|
|
|
|
}
|
|
return 0;
|
|
}
|