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Russ Dill61fb4892002-10-14 21:41:28 +00001/* dhcpc.c
2 *
3 * udhcp DHCP client
4 *
5 * Russ Dill <Russ.Dill@asu.edu> July 2001
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
11 *
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
16 *
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 */
21
22#include <stdio.h>
23#include <sys/time.h>
24#include <sys/types.h>
25#include <sys/file.h>
26#include <unistd.h>
27#include <getopt.h>
28#include <stdlib.h>
29#include <sys/socket.h>
30#include <netinet/in.h>
31#include <arpa/inet.h>
32#include <signal.h>
33#include <time.h>
34#include <string.h>
35#include <sys/ioctl.h>
36#include <net/if.h>
37#include <errno.h>
38
39#include "dhcpd.h"
40#include "dhcpc.h"
41#include "options.h"
42#include "clientpacket.h"
43#include "packet.h"
44#include "script.h"
45#include "socket.h"
46#include "debug.h"
47#include "pidfile.h"
48
49static int state;
50static unsigned long requested_ip; /* = 0 */
51static unsigned long server_addr;
52static unsigned long timeout;
53static int packet_num; /* = 0 */
54static int fd;
55static int signal_pipe[2];
56
57#define LISTEN_NONE 0
58#define LISTEN_KERNEL 1
59#define LISTEN_RAW 2
60static int listen_mode;
61
62#define DEFAULT_SCRIPT "/usr/share/udhcpc/default.script"
63
64struct client_config_t client_config = {
65 /* Default options. */
66 abort_if_no_lease: 0,
67 foreground: 0,
68 quit_after_lease: 0,
69 background_if_no_lease: 0,
70 interface: "eth0",
71 pidfile: NULL,
72 script: DEFAULT_SCRIPT,
73 clientid: NULL,
74 hostname: NULL,
75 ifindex: 0,
76 arp: "\0\0\0\0\0\0", /* appease gcc-3.0 */
77};
78
79#ifndef BB_VER
Eric Andersend7e1a6c2002-12-11 07:46:30 +000080static void __attribute__ ((noreturn)) show_usage(void)
Russ Dill61fb4892002-10-14 21:41:28 +000081{
82 printf(
83"Usage: udhcpc [OPTIONS]\n\n"
84" -c, --clientid=CLIENTID Client identifier\n"
85" -H, --hostname=HOSTNAME Client hostname\n"
86" -h Alias for -H\n"
87" -f, --foreground Do not fork after getting lease\n"
88" -b, --background Fork to background if lease cannot be\n"
89" immediately negotiated.\n"
90" -i, --interface=INTERFACE Interface to use (default: eth0)\n"
91" -n, --now Exit with failure if lease cannot be\n"
92" immediately negotiated.\n"
93" -p, --pidfile=file Store process ID of daemon in file\n"
94" -q, --quit Quit after obtaining lease\n"
95" -r, --request=IP IP address to request (default: none)\n"
96" -s, --script=file Run file at dhcp events (default:\n"
97" " DEFAULT_SCRIPT ")\n"
98" -v, --version Display version\n"
99 );
100 exit(0);
101}
Eric Andersend7e1a6c2002-12-11 07:46:30 +0000102#else
103extern void show_usage(void) __attribute__ ((noreturn));
Russ Dill61fb4892002-10-14 21:41:28 +0000104#endif
105
106
107/* just a little helper */
108static void change_mode(int new_mode)
109{
110 DEBUG(LOG_INFO, "entering %s listen mode",
111 new_mode ? (new_mode == 1 ? "kernel" : "raw") : "none");
112 close(fd);
113 fd = -1;
114 listen_mode = new_mode;
115}
116
117
118/* perform a renew */
119static void perform_renew(void)
120{
121 LOG(LOG_INFO, "Performing a DHCP renew");
122 switch (state) {
Russ Dill61fb4892002-10-14 21:41:28 +0000123 case BOUND:
Russ Dill61fb4892002-10-14 21:41:28 +0000124 change_mode(LISTEN_KERNEL);
Russ Dillf5ecd432002-10-31 19:21:27 +0000125 case RENEWING:
126 case REBINDING:
Russ Dill61fb4892002-10-14 21:41:28 +0000127 state = RENEW_REQUESTED;
128 break;
Russ Dillf5ecd432002-10-31 19:21:27 +0000129 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
130 run_script(NULL, "deconfig");
Russ Dill61fb4892002-10-14 21:41:28 +0000131 case REQUESTING:
132 case RELEASED:
133 change_mode(LISTEN_RAW);
134 state = INIT_SELECTING;
135 break;
136 case INIT_SELECTING:
137 }
138
139 /* start things over */
140 packet_num = 0;
141
142 /* Kill any timeouts because the user wants this to hurry along */
143 timeout = 0;
144}
145
146
147/* perform a release */
148static void perform_release(void)
149{
150 char buffer[16];
151 struct in_addr temp_addr;
152
153 /* send release packet */
154 if (state == BOUND || state == RENEWING || state == REBINDING) {
155 temp_addr.s_addr = server_addr;
156 sprintf(buffer, "%s", inet_ntoa(temp_addr));
157 temp_addr.s_addr = requested_ip;
158 LOG(LOG_INFO, "Unicasting a release of %s to %s",
159 inet_ntoa(temp_addr), buffer);
160 send_release(server_addr, requested_ip); /* unicast */
161 run_script(NULL, "deconfig");
162 }
163 LOG(LOG_INFO, "Entering released state");
164
165 change_mode(LISTEN_NONE);
166 state = RELEASED;
167 timeout = 0x7fffffff;
168}
169
170
171/* Exit and cleanup */
172static void exit_client(int retval)
173{
174 pidfile_delete(client_config.pidfile);
175 CLOSE_LOG();
176 exit(retval);
177}
178
179
180/* Signal handler */
181static void signal_handler(int sig)
182{
183 if (send(signal_pipe[1], &sig, sizeof(sig), MSG_DONTWAIT) < 0) {
184 LOG(LOG_ERR, "Could not send signal: %s",
185 strerror(errno));
186 }
187}
188
189
190static void background(void)
191{
192 int pid_fd;
193
194 pid_fd = pidfile_acquire(client_config.pidfile); /* hold lock during fork. */
195 while (pid_fd >= 0 && pid_fd < 3) pid_fd = dup(pid_fd); /* don't let daemon close it */
196 if (daemon(0, 0) == -1) {
197 perror("fork");
198 exit_client(1);
199 }
200 client_config.foreground = 1; /* Do not fork again. */
201 pidfile_write_release(pid_fd);
202}
203
204
205#ifdef COMBINED_BINARY
206int udhcpc_main(int argc, char *argv[])
207#else
208int main(int argc, char *argv[])
209#endif
210{
211 unsigned char *temp, *message;
212 unsigned long t1 = 0, t2 = 0, xid = 0;
213 unsigned long start = 0, lease;
214 fd_set rfds;
215 int retval;
216 struct timeval tv;
217 int c, len;
218 struct dhcpMessage packet;
219 struct in_addr temp_addr;
220 int pid_fd;
221 time_t now;
222 int max_fd;
223 int sig;
224
225 static struct option arg_options[] = {
226 {"clientid", required_argument, 0, 'c'},
227 {"foreground", no_argument, 0, 'f'},
228 {"background", no_argument, 0, 'b'},
229 {"hostname", required_argument, 0, 'H'},
230 {"hostname", required_argument, 0, 'h'},
231 {"interface", required_argument, 0, 'i'},
232 {"now", no_argument, 0, 'n'},
233 {"pidfile", required_argument, 0, 'p'},
234 {"quit", no_argument, 0, 'q'},
235 {"request", required_argument, 0, 'r'},
236 {"script", required_argument, 0, 's'},
237 {"version", no_argument, 0, 'v'},
238 {"help", no_argument, 0, '?'},
239 {0, 0, 0, 0}
240 };
241
242 /* get options */
243 while (1) {
244 int option_index = 0;
245 c = getopt_long(argc, argv, "c:fbH:h:i:np:qr:s:v", arg_options, &option_index);
246 if (c == -1) break;
247
248 switch (c) {
249 case 'c':
250 len = strlen(optarg) > 255 ? 255 : strlen(optarg);
Russ Dill1eb7a172002-12-11 21:12:45 +0000251 if (client_config.clientid) free(client_config.clientid);
Russ Dill61fb4892002-10-14 21:41:28 +0000252 client_config.clientid = xmalloc(len + 2);
253 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
254 client_config.clientid[OPT_LEN] = len;
255 client_config.clientid[OPT_DATA] = '\0';
256 strncpy(client_config.clientid + OPT_DATA, optarg, len);
257 break;
258 case 'f':
259 client_config.foreground = 1;
260 break;
261 case 'b':
262 client_config.background_if_no_lease = 1;
263 break;
264 case 'h':
265 case 'H':
266 len = strlen(optarg) > 255 ? 255 : strlen(optarg);
Russ Dill1eb7a172002-12-11 21:12:45 +0000267 if (client_config.hostname) free(client_config.hostname);
Russ Dill61fb4892002-10-14 21:41:28 +0000268 client_config.hostname = xmalloc(len + 2);
269 client_config.hostname[OPT_CODE] = DHCP_HOST_NAME;
270 client_config.hostname[OPT_LEN] = len;
271 strncpy(client_config.hostname + 2, optarg, len);
272 break;
273 case 'i':
274 client_config.interface = optarg;
275 break;
276 case 'n':
277 client_config.abort_if_no_lease = 1;
278 break;
279 case 'p':
280 client_config.pidfile = optarg;
281 break;
282 case 'q':
283 client_config.quit_after_lease = 1;
284 break;
285 case 'r':
286 requested_ip = inet_addr(optarg);
287 break;
288 case 's':
289 client_config.script = optarg;
290 break;
291 case 'v':
292 printf("udhcpcd, version %s\n\n", VERSION);
293 exit_client(0);
294 break;
295 default:
296 show_usage();
297 }
298 }
299
300 OPEN_LOG("udhcpc");
301 LOG(LOG_INFO, "udhcp client (v%s) started", VERSION);
302
303 pid_fd = pidfile_acquire(client_config.pidfile);
304 pidfile_write_release(pid_fd);
305
306 if (read_interface(client_config.interface, &client_config.ifindex,
307 NULL, client_config.arp) < 0)
308 exit_client(1);
309
310 if (!client_config.clientid) {
311 client_config.clientid = xmalloc(6 + 3);
312 client_config.clientid[OPT_CODE] = DHCP_CLIENT_ID;
313 client_config.clientid[OPT_LEN] = 7;
314 client_config.clientid[OPT_DATA] = 1;
315 memcpy(client_config.clientid + 3, client_config.arp, 6);
316 }
317
318 /* setup signal handlers */
319 socketpair(AF_UNIX, SOCK_STREAM, 0, signal_pipe);
320 signal(SIGUSR1, signal_handler);
321 signal(SIGUSR2, signal_handler);
322 signal(SIGTERM, signal_handler);
323
324 state = INIT_SELECTING;
325 run_script(NULL, "deconfig");
326 change_mode(LISTEN_RAW);
327
328 for (;;) {
329
330 tv.tv_sec = timeout - time(0);
331 tv.tv_usec = 0;
332 FD_ZERO(&rfds);
333
334 if (listen_mode != LISTEN_NONE && fd < 0) {
335 if (listen_mode == LISTEN_KERNEL)
336 fd = listen_socket(INADDR_ANY, CLIENT_PORT, client_config.interface);
337 else
338 fd = raw_socket(client_config.ifindex);
339 if (fd < 0) {
340 LOG(LOG_ERR, "FATAL: couldn't listen on socket, %s", strerror(errno));
341 exit_client(0);
342 }
343 }
344 if (fd >= 0) FD_SET(fd, &rfds);
345 FD_SET(signal_pipe[0], &rfds);
346
347 if (tv.tv_sec > 0) {
348 DEBUG(LOG_INFO, "Waiting on select...\n");
349 max_fd = signal_pipe[0] > fd ? signal_pipe[0] : fd;
350 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
351 } else retval = 0; /* If we already timed out, fall through */
352
353 now = time(0);
354 if (retval == 0) {
355 /* timeout dropped to zero */
356 switch (state) {
357 case INIT_SELECTING:
358 if (packet_num < 3) {
359 if (packet_num == 0)
360 xid = random_xid();
361
362 /* send discover packet */
363 send_discover(xid, requested_ip); /* broadcast */
364
365 timeout = now + ((packet_num == 2) ? 4 : 2);
366 packet_num++;
367 } else {
368 if (client_config.background_if_no_lease) {
369 LOG(LOG_INFO, "No lease, forking to background.");
370 background();
371 } else if (client_config.abort_if_no_lease) {
372 LOG(LOG_INFO, "No lease, failing.");
373 exit_client(1);
374 }
375 /* wait to try again */
376 packet_num = 0;
377 timeout = now + 60;
378 }
379 break;
380 case RENEW_REQUESTED:
381 case REQUESTING:
382 if (packet_num < 3) {
383 /* send request packet */
384 if (state == RENEW_REQUESTED)
385 send_renew(xid, server_addr, requested_ip); /* unicast */
386 else send_selecting(xid, server_addr, requested_ip); /* broadcast */
387
388 timeout = now + ((packet_num == 2) ? 10 : 2);
389 packet_num++;
390 } else {
391 /* timed out, go back to init state */
Russ Dillf5ecd432002-10-31 19:21:27 +0000392 if (state == RENEW_REQUESTED) run_script(NULL, "deconfig");
Russ Dill61fb4892002-10-14 21:41:28 +0000393 state = INIT_SELECTING;
394 timeout = now;
395 packet_num = 0;
396 change_mode(LISTEN_RAW);
397 }
398 break;
399 case BOUND:
400 /* Lease is starting to run out, time to enter renewing state */
401 state = RENEWING;
402 change_mode(LISTEN_KERNEL);
403 DEBUG(LOG_INFO, "Entering renew state");
404 /* fall right through */
405 case RENEWING:
406 /* Either set a new T1, or enter REBINDING state */
407 if ((t2 - t1) <= (lease / 14400 + 1)) {
408 /* timed out, enter rebinding state */
409 state = REBINDING;
410 timeout = now + (t2 - t1);
411 DEBUG(LOG_INFO, "Entering rebinding state");
412 } else {
413 /* send a request packet */
414 send_renew(xid, server_addr, requested_ip); /* unicast */
415
416 t1 = (t2 - t1) / 2 + t1;
417 timeout = t1 + start;
418 }
419 break;
420 case REBINDING:
421 /* Either set a new T2, or enter INIT state */
422 if ((lease - t2) <= (lease / 14400 + 1)) {
423 /* timed out, enter init state */
424 state = INIT_SELECTING;
425 LOG(LOG_INFO, "Lease lost, entering init state");
426 run_script(NULL, "deconfig");
427 timeout = now;
428 packet_num = 0;
429 change_mode(LISTEN_RAW);
430 } else {
431 /* send a request packet */
432 send_renew(xid, 0, requested_ip); /* broadcast */
433
434 t2 = (lease - t2) / 2 + t2;
435 timeout = t2 + start;
436 }
437 break;
438 case RELEASED:
439 /* yah, I know, *you* say it would never happen */
440 timeout = 0x7fffffff;
441 break;
442 }
443 } else if (retval > 0 && listen_mode != LISTEN_NONE && FD_ISSET(fd, &rfds)) {
444 /* a packet is ready, read it */
445
446 if (listen_mode == LISTEN_KERNEL)
447 len = get_packet(&packet, fd);
448 else len = get_raw_packet(&packet, fd);
449
450 if (len == -1 && errno != EINTR) {
451 DEBUG(LOG_INFO, "error on read, %s, reopening socket", strerror(errno));
452 change_mode(listen_mode); /* just close and reopen */
453 }
454 if (len < 0) continue;
455
456 if (packet.xid != xid) {
457 DEBUG(LOG_INFO, "Ignoring XID %lx (our xid is %lx)",
458 (unsigned long) packet.xid, xid);
459 continue;
460 }
461
462 if ((message = get_option(&packet, DHCP_MESSAGE_TYPE)) == NULL) {
463 DEBUG(LOG_ERR, "couldnt get option from packet -- ignoring");
464 continue;
465 }
466
467 switch (state) {
468 case INIT_SELECTING:
469 /* Must be a DHCPOFFER to one of our xid's */
470 if (*message == DHCPOFFER) {
471 if ((temp = get_option(&packet, DHCP_SERVER_ID))) {
472 memcpy(&server_addr, temp, 4);
473 xid = packet.xid;
474 requested_ip = packet.yiaddr;
475
476 /* enter requesting state */
477 state = REQUESTING;
478 timeout = now;
479 packet_num = 0;
480 } else {
481 DEBUG(LOG_ERR, "No server ID in message");
482 }
483 }
484 break;
485 case RENEW_REQUESTED:
486 case REQUESTING:
487 case RENEWING:
488 case REBINDING:
489 if (*message == DHCPACK) {
490 if (!(temp = get_option(&packet, DHCP_LEASE_TIME))) {
491 LOG(LOG_ERR, "No lease time with ACK, using 1 hour lease");
492 lease = 60 * 60;
493 } else {
494 memcpy(&lease, temp, 4);
495 lease = ntohl(lease);
496 }
497
498 /* enter bound state */
499 t1 = lease / 2;
500
501 /* little fixed point for n * .875 */
502 t2 = (lease * 0x7) >> 3;
503 temp_addr.s_addr = packet.yiaddr;
504 LOG(LOG_INFO, "Lease of %s obtained, lease time %ld",
505 inet_ntoa(temp_addr), lease);
506 start = now;
507 timeout = t1 + start;
508 requested_ip = packet.yiaddr;
509 run_script(&packet,
510 ((state == RENEWING || state == REBINDING) ? "renew" : "bound"));
511
512 state = BOUND;
513 change_mode(LISTEN_NONE);
514 if (client_config.quit_after_lease)
515 exit_client(0);
516 if (!client_config.foreground)
517 background();
518
519 } else if (*message == DHCPNAK) {
520 /* return to init state */
521 LOG(LOG_INFO, "Received DHCP NAK");
522 run_script(&packet, "nak");
523 if (state != REQUESTING)
524 run_script(NULL, "deconfig");
525 state = INIT_SELECTING;
526 timeout = now;
527 requested_ip = 0;
528 packet_num = 0;
529 change_mode(LISTEN_RAW);
530 sleep(3); /* avoid excessive network traffic */
531 }
532 break;
533 /* case BOUND, RELEASED: - ignore all packets */
534 }
535 } else if (retval > 0 && FD_ISSET(signal_pipe[0], &rfds)) {
536 if (read(signal_pipe[0], &sig, sizeof(signal)) < 0) {
537 DEBUG(LOG_ERR, "Could not read signal: %s",
538 strerror(errno));
539 continue; /* probably just EINTR */
540 }
541 switch (sig) {
542 case SIGUSR1:
543 perform_renew();
544 break;
545 case SIGUSR2:
546 perform_release();
547 break;
548 case SIGTERM:
549 LOG(LOG_INFO, "Received SIGTERM");
550 exit_client(0);
551 }
552 } else if (retval == -1 && errno == EINTR) {
553 /* a signal was caught */
554 } else {
555 /* An error occured */
556 DEBUG(LOG_ERR, "Error on select");
557 }
558
559 }
560 return 0;
561}
562