source: MondoRescue/branches/2.2.9/mindi-busybox/networking/udhcp/dhcpc.c@ 2725

Last change on this file since 2725 was 2725, checked in by Bruno Cornec, 13 years ago
  • Update mindi-busybox to 1.18.3 to avoid problems with the tar command which is now failing on recent versions with busybox 1.7.3
File size: 45.9 KB
Line 
1/* vi: set sw=4 ts=4: */
2/*
3 * udhcp 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#include <syslog.h>
22/* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
23#define WANT_PIDFILE 1
24#include "common.h"
25#include "dhcpd.h"
26#include "dhcpc.h"
27
28#include <asm/types.h>
29#if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined(_NEWLIB_VERSION)
30# include <netpacket/packet.h>
31# include <net/ethernet.h>
32#else
33# include <linux/if_packet.h>
34# include <linux/if_ether.h>
35#endif
36#include <linux/filter.h>
37
38/* struct client_config_t client_config is in bb_common_bufsiz1 */
39
40
41/*** Script execution code ***/
42
43/* get a rough idea of how long an option will be (rounding up...) */
44static const uint8_t len_of_option_as_string[] = {
45 [OPTION_IP ] = sizeof("255.255.255.255 "),
46 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
47 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
48 [OPTION_STRING ] = 1,
49#if ENABLE_FEATURE_UDHCP_RFC3397
50 [OPTION_DNS_STRING ] = 1, /* unused */
51 /* Hmmm, this severely overestimates size if SIP_SERVERS option
52 * is in domain name form: N-byte option in binary form
53 * mallocs ~16*N bytes. But it is freed almost at once.
54 */
55 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
56#endif
57// [OPTION_BOOLEAN ] = sizeof("yes "),
58 [OPTION_U8 ] = sizeof("255 "),
59 [OPTION_U16 ] = sizeof("65535 "),
60// [OPTION_S16 ] = sizeof("-32768 "),
61 [OPTION_U32 ] = sizeof("4294967295 "),
62 [OPTION_S32 ] = sizeof("-2147483684 "),
63};
64
65/* note: ip is a pointer to an IP in network order, possibly misaliged */
66static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
67{
68 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
69}
70
71/* really simple implementation, just count the bits */
72static int mton(uint32_t mask)
73{
74 int i = 0;
75 mask = ntohl(mask); /* 111110000-like bit pattern */
76 while (mask) {
77 i++;
78 mask <<= 1;
79 }
80 return i;
81}
82
83/* Create "opt_name=opt_value" string */
84static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
85{
86 unsigned upper_length;
87 int len, type, optlen;
88 char *dest, *ret;
89
90 /* option points to OPT_DATA, need to go back and get OPT_LEN */
91 len = option[OPT_LEN - OPT_DATA];
92
93 type = optflag->flags & OPTION_TYPE_MASK;
94 optlen = dhcp_option_lengths[type];
95 upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen);
96
97 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
98 dest += sprintf(ret, "%s=", opt_name);
99
100 while (len >= optlen) {
101 unsigned ip_ofs = 0;
102
103 switch (type) {
104 case OPTION_IP_PAIR:
105 dest += sprint_nip(dest, "", option);
106 *dest++ = '/';
107 ip_ofs = 4;
108 /* fall through */
109 case OPTION_IP:
110 dest += sprint_nip(dest, "", option + ip_ofs);
111 break;
112// case OPTION_BOOLEAN:
113// dest += sprintf(dest, *option ? "yes" : "no");
114// break;
115 case OPTION_U8:
116 dest += sprintf(dest, "%u", *option);
117 break;
118// case OPTION_S16:
119 case OPTION_U16: {
120 uint16_t val_u16;
121 move_from_unaligned16(val_u16, option);
122 dest += sprintf(dest, "%u", ntohs(val_u16));
123 break;
124 }
125 case OPTION_S32:
126 case OPTION_U32: {
127 uint32_t val_u32;
128 move_from_unaligned32(val_u32, option);
129 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
130 break;
131 }
132 case OPTION_STRING:
133 memcpy(dest, option, len);
134 dest[len] = '\0';
135 return ret; /* Short circuit this case */
136 case OPTION_STATIC_ROUTES: {
137 /* Option binary format:
138 * mask [one byte, 0..32]
139 * ip [big endian, 0..4 bytes depending on mask]
140 * router [big endian, 4 bytes]
141 * may be repeated
142 *
143 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
144 */
145 const char *pfx = "";
146
147 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
148 uint32_t nip;
149 uint8_t *p;
150 unsigned mask;
151 int bytes;
152
153 mask = *option++;
154 if (mask > 32)
155 break;
156 len--;
157
158 nip = 0;
159 p = (void*) &nip;
160 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
161 while (--bytes >= 0) {
162 *p++ = *option++;
163 len--;
164 }
165 if (len < 4)
166 break;
167
168 /* print ip/mask */
169 dest += sprint_nip(dest, pfx, (void*) &nip);
170 pfx = " ";
171 dest += sprintf(dest, "/%u ", mask);
172 /* print router */
173 dest += sprint_nip(dest, "", option);
174 option += 4;
175 len -= 4;
176 }
177
178 return ret;
179 }
180#if ENABLE_FEATURE_UDHCP_RFC3397
181 case OPTION_DNS_STRING:
182 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
183 dest = dname_dec(option, len, ret);
184 if (dest) {
185 free(ret);
186 return dest;
187 }
188 /* error. return "optname=" string */
189 return ret;
190 case OPTION_SIP_SERVERS:
191 /* Option binary format:
192 * type: byte
193 * type=0: domain names, dns-compressed
194 * type=1: IP addrs
195 */
196 option++;
197 len--;
198 if (option[-1] == 0) {
199 dest = dname_dec(option, len, ret);
200 if (dest) {
201 free(ret);
202 return dest;
203 }
204 } else
205 if (option[-1] == 1) {
206 const char *pfx = "";
207 while (1) {
208 len -= 4;
209 if (len < 0)
210 break;
211 dest += sprint_nip(dest, pfx, option);
212 pfx = " ";
213 option += 4;
214 }
215 }
216 return ret;
217#endif
218 } /* switch */
219 option += optlen;
220 len -= optlen;
221// TODO: it can be a list only if (optflag->flags & OPTION_LIST).
222// Should we bail out/warn if we see multi-ip option which is
223// not allowed to be such (for example, DHCP_BROADCAST)? -
224 if (len <= 0 /* || !(optflag->flags & OPTION_LIST) */)
225 break;
226 *dest++ = ' ';
227 *dest = '\0';
228 }
229 return ret;
230}
231
232/* put all the parameters into the environment */
233static char **fill_envp(struct dhcp_packet *packet)
234{
235 int envc;
236 int i;
237 char **envp, **curr;
238 const char *opt_name;
239 uint8_t *temp;
240 uint8_t overload = 0;
241
242 /* We need 6 elements for:
243 * "interface=IFACE"
244 * "ip=N.N.N.N" from packet->yiaddr
245 * "siaddr=IP" from packet->siaddr_nip (unless 0)
246 * "boot_file=FILE" from packet->file (unless overloaded)
247 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
248 * terminating NULL
249 */
250 envc = 6;
251 /* +1 element for each option, +2 for subnet option: */
252 if (packet) {
253 for (i = 0; dhcp_optflags[i].code; i++) {
254 if (udhcp_get_option(packet, dhcp_optflags[i].code)) {
255 if (dhcp_optflags[i].code == DHCP_SUBNET)
256 envc++; /* for mton */
257 envc++;
258 }
259 }
260 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
261 if (temp)
262 overload = *temp;
263 }
264 curr = envp = xzalloc(sizeof(char *) * envc);
265
266 *curr = xasprintf("interface=%s", client_config.interface);
267 putenv(*curr++);
268
269 if (!packet)
270 return envp;
271
272 *curr = xmalloc(sizeof("ip=255.255.255.255"));
273 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
274 putenv(*curr++);
275
276 opt_name = dhcp_option_strings;
277 i = 0;
278 while (*opt_name) {
279 temp = udhcp_get_option(packet, dhcp_optflags[i].code);
280 if (!temp)
281 goto next;
282 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
283 putenv(*curr++);
284 if (dhcp_optflags[i].code == DHCP_SUBNET) {
285 /* Subnet option: make things like "$ip/$mask" possible */
286 uint32_t subnet;
287 move_from_unaligned32(subnet, temp);
288 *curr = xasprintf("mask=%d", mton(subnet));
289 putenv(*curr++);
290 }
291 next:
292 opt_name += strlen(opt_name) + 1;
293 i++;
294 }
295 if (packet->siaddr_nip) {
296 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
297 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
298 putenv(*curr++);
299 }
300 if (!(overload & FILE_FIELD) && packet->file[0]) {
301 /* watch out for invalid packets */
302 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
303 putenv(*curr++);
304 }
305 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
306 /* watch out for invalid packets */
307 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
308 putenv(*curr++);
309 }
310 return envp;
311}
312
313/* Call a script with a par file and env vars */
314static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
315{
316 char **envp, **curr;
317 char *argv[3];
318
319 if (client_config.script == NULL)
320 return;
321
322 envp = fill_envp(packet);
323
324 /* call script */
325 log1("Executing %s %s", client_config.script, name);
326 argv[0] = (char*) client_config.script;
327 argv[1] = (char*) name;
328 argv[2] = NULL;
329 spawn_and_wait(argv);
330
331 for (curr = envp; *curr; curr++) {
332 log2(" %s", *curr);
333 bb_unsetenv_and_free(*curr);
334 }
335 free(envp);
336}
337
338
339/*** Sending/receiving packets ***/
340
341static ALWAYS_INLINE uint32_t random_xid(void)
342{
343 return rand();
344}
345
346/* Initialize the packet with the proper defaults */
347static void init_packet(struct dhcp_packet *packet, char type)
348{
349 /* Fill in: op, htype, hlen, cookie fields; message type option: */
350 udhcp_init_header(packet, type);
351
352 packet->xid = random_xid();
353
354 memcpy(packet->chaddr, client_config.client_mac, 6);
355 if (client_config.clientid)
356 udhcp_add_binary_option(packet, client_config.clientid);
357}
358
359static void add_client_options(struct dhcp_packet *packet)
360{
361 uint8_t c;
362 int i, end, len;
363
364 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
365
366 /* Add a "param req" option with the list of options we'd like to have
367 * from stubborn DHCP servers. Pull the data from the struct in common.c.
368 * No bounds checking because it goes towards the head of the packet. */
369 end = udhcp_end_option(packet->options);
370 len = 0;
371 for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
372 if (( (dhcp_optflags[i].flags & OPTION_REQ)
373 && !client_config.no_default_options
374 )
375 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
376 ) {
377 packet->options[end + OPT_DATA + len] = c;
378 len++;
379 }
380 }
381 if (len) {
382 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
383 packet->options[end + OPT_LEN] = len;
384 packet->options[end + OPT_DATA + len] = DHCP_END;
385 }
386
387 if (client_config.vendorclass)
388 udhcp_add_binary_option(packet, client_config.vendorclass);
389 if (client_config.hostname)
390 udhcp_add_binary_option(packet, client_config.hostname);
391 if (client_config.fqdn)
392 udhcp_add_binary_option(packet, client_config.fqdn);
393
394 /* Add -x options if any */
395 {
396 struct option_set *curr = client_config.options;
397 while (curr) {
398 udhcp_add_binary_option(packet, curr->data);
399 curr = curr->next;
400 }
401// if (client_config.sname)
402// strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
403// if (client_config.boot_file)
404// strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
405 }
406}
407
408/* RFC 2131
409 * 4.4.4 Use of broadcast and unicast
410 *
411 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
412 * messages, unless the client knows the address of a DHCP server.
413 * The client unicasts DHCPRELEASE messages to the server. Because
414 * the client is declining the use of the IP address supplied by the server,
415 * the client broadcasts DHCPDECLINE messages.
416 *
417 * When the DHCP client knows the address of a DHCP server, in either
418 * INIT or REBOOTING state, the client may use that address
419 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
420 * The client may also use unicast to send DHCPINFORM messages
421 * to a known DHCP server. If the client receives no response to DHCP
422 * messages sent to the IP address of a known DHCP server, the DHCP
423 * client reverts to using the IP broadcast address.
424 */
425
426static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
427{
428 return udhcp_send_raw_packet(packet,
429 /*src*/ INADDR_ANY, CLIENT_PORT,
430 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
431 client_config.ifindex);
432}
433
434/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
435/* NOINLINE: limit stack usage in caller */
436static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
437{
438 struct dhcp_packet packet;
439
440 /* Fill in: op, htype, hlen, cookie, chaddr fields,
441 * random xid field (we override it below),
442 * client-id option (unless -C), message type option:
443 */
444 init_packet(&packet, DHCPDISCOVER);
445
446 packet.xid = xid;
447 if (requested)
448 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
449
450 /* Add options: maxsize,
451 * optionally: hostname, fqdn, vendorclass,
452 * "param req" option according to -O, options specified with -x
453 */
454 add_client_options(&packet);
455
456 bb_info_msg("Sending discover...");
457 return raw_bcast_from_client_config_ifindex(&packet);
458}
459
460/* Broadcast a DHCP request message */
461/* RFC 2131 3.1 paragraph 3:
462 * "The client _broadcasts_ a DHCPREQUEST message..."
463 */
464/* NOINLINE: limit stack usage in caller */
465static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
466{
467 struct dhcp_packet packet;
468 struct in_addr addr;
469
470/*
471 * RFC 2131 4.3.2 DHCPREQUEST message
472 * ...
473 * If the DHCPREQUEST message contains a 'server identifier'
474 * option, the message is in response to a DHCPOFFER message.
475 * Otherwise, the message is a request to verify or extend an
476 * existing lease. If the client uses a 'client identifier'
477 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
478 * in all subsequent messages. If the client included a list
479 * of requested parameters in a DHCPDISCOVER message, it MUST
480 * include that list in all subsequent messages.
481 */
482 /* Fill in: op, htype, hlen, cookie, chaddr fields,
483 * random xid field (we override it below),
484 * client-id option (unless -C), message type option:
485 */
486 init_packet(&packet, DHCPREQUEST);
487
488 packet.xid = xid;
489 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
490
491 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
492
493 /* Add options: maxsize,
494 * optionally: hostname, fqdn, vendorclass,
495 * "param req" option according to -O, and options specified with -x
496 */
497 add_client_options(&packet);
498
499 addr.s_addr = requested;
500 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
501 return raw_bcast_from_client_config_ifindex(&packet);
502}
503
504/* Unicast or broadcast a DHCP renew message */
505/* NOINLINE: limit stack usage in caller */
506static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
507{
508 struct dhcp_packet packet;
509
510/*
511 * RFC 2131 4.3.2 DHCPREQUEST message
512 * ...
513 * DHCPREQUEST generated during RENEWING state:
514 *
515 * 'server identifier' MUST NOT be filled in, 'requested IP address'
516 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
517 * client's IP address. In this situation, the client is completely
518 * configured, and is trying to extend its lease. This message will
519 * be unicast, so no relay agents will be involved in its
520 * transmission. Because 'giaddr' is therefore not filled in, the
521 * DHCP server will trust the value in 'ciaddr', and use it when
522 * replying to the client.
523 */
524 /* Fill in: op, htype, hlen, cookie, chaddr fields,
525 * random xid field (we override it below),
526 * client-id option (unless -C), message type option:
527 */
528 init_packet(&packet, DHCPREQUEST);
529
530 packet.xid = xid;
531 packet.ciaddr = ciaddr;
532
533 /* Add options: maxsize,
534 * optionally: hostname, fqdn, vendorclass,
535 * "param req" option according to -O, and options specified with -x
536 */
537 add_client_options(&packet);
538
539 bb_info_msg("Sending renew...");
540 if (server)
541 return udhcp_send_kernel_packet(&packet,
542 ciaddr, CLIENT_PORT,
543 server, SERVER_PORT);
544 return raw_bcast_from_client_config_ifindex(&packet);
545}
546
547#if ENABLE_FEATURE_UDHCPC_ARPING
548/* Broadcast a DHCP decline message */
549/* NOINLINE: limit stack usage in caller */
550static NOINLINE int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
551{
552 struct dhcp_packet packet;
553
554 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
555 * client-id option (unless -C), message type option:
556 */
557 init_packet(&packet, DHCPDECLINE);
558
559 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
560 * but in case the server is buggy and wants DHCPDECLINE's xid
561 * to match the xid which started entire handshake,
562 * we use the same xid we used in initial DHCPDISCOVER:
563 */
564 packet.xid = xid;
565 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
566 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
567
568 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
569
570 bb_info_msg("Sending decline...");
571 return raw_bcast_from_client_config_ifindex(&packet);
572}
573#endif
574
575/* Unicast a DHCP release message */
576static int send_release(uint32_t server, uint32_t ciaddr)
577{
578 struct dhcp_packet packet;
579
580 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
581 * client-id option (unless -C), message type option:
582 */
583 init_packet(&packet, DHCPRELEASE);
584
585 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
586 packet.ciaddr = ciaddr;
587
588 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
589
590 bb_info_msg("Sending release...");
591 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
592}
593
594/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
595/* NOINLINE: limit stack usage in caller */
596static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
597{
598 int bytes;
599 struct ip_udp_dhcp_packet packet;
600 uint16_t check;
601
602 memset(&packet, 0, sizeof(packet));
603 bytes = safe_read(fd, &packet, sizeof(packet));
604 if (bytes < 0) {
605 log1("Packet read error, ignoring");
606 /* NB: possible down interface, etc. Caller should pause. */
607 return bytes; /* returns -1 */
608 }
609
610 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
611 log1("Packet is too short, ignoring");
612 return -2;
613 }
614
615 if (bytes < ntohs(packet.ip.tot_len)) {
616 /* packet is bigger than sizeof(packet), we did partial read */
617 log1("Oversized packet, ignoring");
618 return -2;
619 }
620
621 /* ignore any extra garbage bytes */
622 bytes = ntohs(packet.ip.tot_len);
623
624 /* make sure its the right packet for us, and that it passes sanity checks */
625 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
626 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
627 || packet.udp.dest != htons(CLIENT_PORT)
628 /* || bytes > (int) sizeof(packet) - can't happen */
629 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
630 ) {
631 log1("Unrelated/bogus packet, ignoring");
632 return -2;
633 }
634
635 /* verify IP checksum */
636 check = packet.ip.check;
637 packet.ip.check = 0;
638 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
639 log1("Bad IP header checksum, ignoring");
640 return -2;
641 }
642
643 /* verify UDP checksum. IP header has to be modified for this */
644 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
645 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
646 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
647 check = packet.udp.check;
648 packet.udp.check = 0;
649 if (check && check != udhcp_checksum(&packet, bytes)) {
650 log1("Packet with bad UDP checksum received, ignoring");
651 return -2;
652 }
653
654 memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
655
656 if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
657 bb_info_msg("Packet with bad magic, ignoring");
658 return -2;
659 }
660 log1("Got valid DHCP packet");
661 udhcp_dump_packet(dhcp_pkt);
662 return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
663}
664
665
666/*** Main ***/
667
668static int sockfd = -1;
669
670#define LISTEN_NONE 0
671#define LISTEN_KERNEL 1
672#define LISTEN_RAW 2
673static smallint listen_mode;
674
675/* initial state: (re)start DHCP negotiation */
676#define INIT_SELECTING 0
677/* discover was sent, DHCPOFFER reply received */
678#define REQUESTING 1
679/* select/renew was sent, DHCPACK reply received */
680#define BOUND 2
681/* half of lease passed, want to renew it by sending unicast renew requests */
682#define RENEWING 3
683/* renew requests were not answered, lease is almost over, send broadcast renew */
684#define REBINDING 4
685/* manually requested renew (SIGUSR1) */
686#define RENEW_REQUESTED 5
687/* release, possibly manually requested (SIGUSR2) */
688#define RELEASED 6
689static smallint state;
690
691static int udhcp_raw_socket(int ifindex)
692{
693 int fd;
694 struct sockaddr_ll sock;
695
696 /*
697 * Comment:
698 *
699 * I've selected not to see LL header, so BPF doesn't see it, too.
700 * The filter may also pass non-IP and non-ARP packets, but we do
701 * a more complete check when receiving the message in userspace.
702 *
703 * and filter shamelessly stolen from:
704 *
705 * http://www.flamewarmaster.de/software/dhcpclient/
706 *
707 * There are a few other interesting ideas on that page (look under
708 * "Motivation"). Use of netlink events is most interesting. Think
709 * of various network servers listening for events and reconfiguring.
710 * That would obsolete sending HUP signals and/or make use of restarts.
711 *
712 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
713 * License: GPL v2.
714 *
715 * TODO: make conditional?
716 */
717#define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68)
718 static const struct sock_filter filter_instr[] = {
719 /* check for udp */
720 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
721 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */
722 /* ugly check for arp on ethernet-like and IPv4 */
723 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */
724 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */
725 /* skip IP header */
726 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */
727 /* check udp source and destination ports */
728 BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
729 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */
730 /* returns */
731 BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */
732 BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */
733 };
734 static const struct sock_fprog filter_prog = {
735 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
736 /* casting const away: */
737 .filter = (struct sock_filter *) filter_instr,
738 };
739
740 log1("Opening raw socket on ifindex %d", ifindex); //log2?
741
742 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
743 log1("Got raw socket fd %d", fd); //log2?
744
745 if (SERVER_PORT == 67 && CLIENT_PORT == 68) {
746 /* Use only if standard ports are in use */
747 /* Ignoring error (kernel may lack support for this) */
748 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
749 sizeof(filter_prog)) >= 0)
750 log1("Attached filter to raw socket fd %d", fd); // log?
751 }
752
753 sock.sll_family = AF_PACKET;
754 sock.sll_protocol = htons(ETH_P_IP);
755 sock.sll_ifindex = ifindex;
756 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
757 log1("Created raw socket");
758
759 return fd;
760}
761
762static void change_listen_mode(int new_mode)
763{
764 log1("Entering listen mode: %s",
765 new_mode != LISTEN_NONE
766 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
767 : "none"
768 );
769
770 listen_mode = new_mode;
771 if (sockfd >= 0) {
772 close(sockfd);
773 sockfd = -1;
774 }
775 if (new_mode == LISTEN_KERNEL)
776 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
777 else if (new_mode != LISTEN_NONE)
778 sockfd = udhcp_raw_socket(client_config.ifindex);
779 /* else LISTEN_NONE: sockfd stays closed */
780}
781
782static void perform_renew(void)
783{
784 bb_info_msg("Performing a DHCP renew");
785 switch (state) {
786 case BOUND:
787 change_listen_mode(LISTEN_KERNEL);
788 case RENEWING:
789 case REBINDING:
790 state = RENEW_REQUESTED;
791 break;
792 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
793 udhcp_run_script(NULL, "deconfig");
794 case REQUESTING:
795 case RELEASED:
796 change_listen_mode(LISTEN_RAW);
797 state = INIT_SELECTING;
798 break;
799 case INIT_SELECTING:
800 break;
801 }
802}
803
804static void perform_release(uint32_t requested_ip, uint32_t server_addr)
805{
806 char buffer[sizeof("255.255.255.255")];
807 struct in_addr temp_addr;
808
809 /* send release packet */
810 if (state == BOUND || state == RENEWING || state == REBINDING) {
811 temp_addr.s_addr = server_addr;
812 strcpy(buffer, inet_ntoa(temp_addr));
813 temp_addr.s_addr = requested_ip;
814 bb_info_msg("Unicasting a release of %s to %s",
815 inet_ntoa(temp_addr), buffer);
816 send_release(server_addr, requested_ip); /* unicast */
817 udhcp_run_script(NULL, "deconfig");
818 }
819 bb_info_msg("Entering released state");
820
821 change_listen_mode(LISTEN_NONE);
822 state = RELEASED;
823}
824
825static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
826{
827 uint8_t *storage;
828 int len = strnlen(str, 255);
829 storage = xzalloc(len + extra + OPT_DATA);
830 storage[OPT_CODE] = code;
831 storage[OPT_LEN] = len + extra;
832 memcpy(storage + extra + OPT_DATA, str, len);
833 return storage;
834}
835
836#if BB_MMU
837static void client_background(void)
838{
839 bb_daemonize(0);
840 logmode &= ~LOGMODE_STDIO;
841 /* rewrite pidfile, as our pid is different now */
842 write_pidfile(client_config.pidfile);
843}
844#endif
845
846//usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
847//usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
848//usage:#else
849//usage:# define IF_UDHCP_VERBOSE(...)
850//usage:#endif
851//usage:#define udhcpc_trivial_usage
852//usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCR] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
853//usage: " [-H HOSTNAME] [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
854//usage:#define udhcpc_full_usage "\n"
855//usage: IF_LONG_OPTS(
856//usage: "\n -i,--interface IFACE Interface to use (default eth0)"
857//usage: "\n -p,--pidfile FILE Create pidfile"
858//usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
859//usage: "\n -t,--retries N Send up to N discover packets"
860//usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
861//usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
862//usage: "\n -f,--foreground Run in foreground"
863//usage: USE_FOR_MMU(
864//usage: "\n -b,--background Background if lease is not obtained"
865//usage: )
866//usage: "\n -n,--now Exit if lease is not obtained"
867//usage: "\n -q,--quit Exit after obtaining lease"
868//usage: "\n -R,--release Release IP on exit"
869//usage: "\n -S,--syslog Log to syslog too"
870//usage: IF_FEATURE_UDHCP_PORT(
871//usage: "\n -P,--client-port N Use port N (default 68)"
872//usage: )
873//usage: IF_FEATURE_UDHCPC_ARPING(
874//usage: "\n -a,--arping Use arping to validate offered address"
875//usage: )
876//usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
877//usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
878//usage: "\n -r,--request IP Request this IP address"
879//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
880//usage: "\n Examples of string, numeric, and hex byte opts:"
881//usage: "\n -x hostname:bbox - option 12"
882//usage: "\n -x lease:3600 - option 51 (lease time)"
883//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
884//usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
885//usage: "\n -H,-h,--hostname NAME Send NAME as client hostname (default none)"
886//usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
887//usage: "\n -C,--clientid-none Don't send MAC as client identifier"
888//usage: IF_UDHCP_VERBOSE(
889//usage: "\n -v Verbose"
890//usage: )
891//usage: )
892//usage: IF_NOT_LONG_OPTS(
893//usage: "\n -i IFACE Interface to use (default eth0)"
894//usage: "\n -p FILE Create pidfile"
895//usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
896//usage: "\n -t N Send up to N discover packets"
897//usage: "\n -T N Pause between packets (default 3 seconds)"
898//usage: "\n -A N Wait N seconds (default 20) after failure"
899//usage: "\n -f Run in foreground"
900//usage: USE_FOR_MMU(
901//usage: "\n -b Background if lease is not obtained"
902//usage: )
903//usage: "\n -n Exit if lease is not obtained"
904//usage: "\n -q Exit after obtaining lease"
905//usage: "\n -R Release IP on exit"
906//usage: "\n -S Log to syslog too"
907//usage: IF_FEATURE_UDHCP_PORT(
908//usage: "\n -P N Use port N (default 68)"
909//usage: )
910//usage: IF_FEATURE_UDHCPC_ARPING(
911//usage: "\n -a Use arping to validate offered address"
912//usage: )
913//usage: "\n -O OPT Request option OPT from server (cumulative)"
914//usage: "\n -o Don't request any options (unless -O is given)"
915//usage: "\n -r IP Request this IP address"
916//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
917//usage: "\n Examples of string, numeric, and hex byte opts:"
918//usage: "\n -x hostname:bbox - option 12"
919//usage: "\n -x lease:3600 - option 51 (lease time)"
920//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
921//usage: "\n -F NAME Ask server to update DNS mapping for NAME"
922//usage: "\n -H,-h NAME Send NAME as client hostname (default none)"
923//usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
924//usage: "\n -C Don't send MAC as client identifier"
925//usage: IF_UDHCP_VERBOSE(
926//usage: "\n -v Verbose"
927//usage: )
928//usage: )
929
930int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
931int udhcpc_main(int argc UNUSED_PARAM, char **argv)
932{
933 uint8_t *temp, *message;
934 const char *str_V, *str_h, *str_F, *str_r;
935 IF_FEATURE_UDHCP_PORT(char *str_P;)
936 void *clientid_mac_ptr;
937 llist_t *list_O = NULL;
938 llist_t *list_x = NULL;
939 int tryagain_timeout = 20;
940 int discover_timeout = 3;
941 int discover_retries = 3;
942 uint32_t server_addr = server_addr; /* for compiler */
943 uint32_t requested_ip = 0;
944 uint32_t xid = 0;
945 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
946 int packet_num;
947 int timeout; /* must be signed */
948 unsigned already_waited_sec;
949 unsigned opt;
950 int max_fd;
951 int retval;
952 struct timeval tv;
953 struct dhcp_packet packet;
954 fd_set rfds;
955
956#if ENABLE_LONG_OPTS
957 static const char udhcpc_longopts[] ALIGN1 =
958 "clientid-none\0" No_argument "C"
959 "vendorclass\0" Required_argument "V"
960 "hostname\0" Required_argument "H"
961 "fqdn\0" Required_argument "F"
962 "interface\0" Required_argument "i"
963 "now\0" No_argument "n"
964 "pidfile\0" Required_argument "p"
965 "quit\0" No_argument "q"
966 "release\0" No_argument "R"
967 "request\0" Required_argument "r"
968 "script\0" Required_argument "s"
969 "timeout\0" Required_argument "T"
970 "version\0" No_argument "v"
971 "retries\0" Required_argument "t"
972 "tryagain\0" Required_argument "A"
973 "syslog\0" No_argument "S"
974 "request-option\0" Required_argument "O"
975 "no-default-options\0" No_argument "o"
976 "foreground\0" No_argument "f"
977 "background\0" No_argument "b"
978 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
979 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
980 ;
981#endif
982 enum {
983 OPT_C = 1 << 0,
984 OPT_V = 1 << 1,
985 OPT_H = 1 << 2,
986 OPT_h = 1 << 3,
987 OPT_F = 1 << 4,
988 OPT_i = 1 << 5,
989 OPT_n = 1 << 6,
990 OPT_p = 1 << 7,
991 OPT_q = 1 << 8,
992 OPT_R = 1 << 9,
993 OPT_r = 1 << 10,
994 OPT_s = 1 << 11,
995 OPT_T = 1 << 12,
996 OPT_t = 1 << 13,
997 OPT_S = 1 << 14,
998 OPT_A = 1 << 15,
999 OPT_O = 1 << 16,
1000 OPT_o = 1 << 17,
1001 OPT_x = 1 << 18,
1002 OPT_f = 1 << 19,
1003/* The rest has variable bit positions, need to be clever */
1004 OPTBIT_f = 19,
1005 USE_FOR_MMU( OPTBIT_b,)
1006 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
1007 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
1008 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
1009 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
1010 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
1011 };
1012
1013 /* Default options */
1014 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1015 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1016 client_config.interface = "eth0";
1017 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1018 str_V = "udhcp "BB_VER;
1019
1020 /* Parse command line */
1021 /* O,x: list; -T,-t,-A take numeric param */
1022 opt_complementary = "O::x::T+:t+:A+"
1023#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1024 ":vv"
1025#endif
1026 ;
1027 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1028 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:f"
1029 USE_FOR_MMU("b")
1030 IF_FEATURE_UDHCPC_ARPING("a")
1031 IF_FEATURE_UDHCP_PORT("P:")
1032 "v"
1033 , &str_V, &str_h, &str_h, &str_F
1034 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1035 , &client_config.script /* s */
1036 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1037 , &list_O
1038 , &list_x
1039 IF_FEATURE_UDHCP_PORT(, &str_P)
1040#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1041 , &dhcp_verbose
1042#endif
1043 );
1044 if (opt & (OPT_h|OPT_H))
1045 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1046 if (opt & OPT_F) {
1047 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1048 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1049 /* Flag bits: 0000NEOS
1050 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1051 * O: 1 = Server indicates to client that DNS has been updated regardless
1052 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1053 * not "host.domain.com". Format 0 is obsolete.
1054 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1055 * Two [0] bytes which follow are deprecated and must be 0.
1056 */
1057 client_config.fqdn[OPT_DATA + 0] = 0x1;
1058 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1059 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1060 }
1061 if (opt & OPT_r)
1062 requested_ip = inet_addr(str_r);
1063#if ENABLE_FEATURE_UDHCP_PORT
1064 if (opt & OPT_P) {
1065 CLIENT_PORT = xatou16(str_P);
1066 SERVER_PORT = CLIENT_PORT - 1;
1067 }
1068#endif
1069 if (opt & OPT_o)
1070 client_config.no_default_options = 1;
1071 while (list_O) {
1072 char *optstr = llist_pop(&list_O);
1073 unsigned n = udhcp_option_idx(optstr);
1074 n = dhcp_optflags[n].code;
1075 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1076 }
1077 while (list_x) {
1078 char *optstr = llist_pop(&list_x);
1079 char *colon = strchr(optstr, ':');
1080 if (colon)
1081 *colon = ' ';
1082 /* now it looks similar to udhcpd's config file line:
1083 * "optname optval", using the common routine: */
1084 udhcp_str2optset(optstr, &client_config.options);
1085 }
1086
1087 if (udhcp_read_interface(client_config.interface,
1088 &client_config.ifindex,
1089 NULL,
1090 client_config.client_mac)
1091 ) {
1092 return 1;
1093 }
1094
1095 clientid_mac_ptr = NULL;
1096 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1097 /* not suppressed and not set, set the default client ID */
1098 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1099 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1100 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1101 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1102 }
1103 if (str_V[0] != '\0')
1104 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1105#if !BB_MMU
1106 /* on NOMMU reexec (i.e., background) early */
1107 if (!(opt & OPT_f)) {
1108 bb_daemonize_or_rexec(0 /* flags */, argv);
1109 logmode = LOGMODE_NONE;
1110 }
1111#endif
1112 if (opt & OPT_S) {
1113 openlog(applet_name, LOG_PID, LOG_DAEMON);
1114 logmode |= LOGMODE_SYSLOG;
1115 }
1116
1117 /* Make sure fd 0,1,2 are open */
1118 bb_sanitize_stdio();
1119 /* Equivalent of doing a fflush after every \n */
1120 setlinebuf(stdout);
1121 /* Create pidfile */
1122 write_pidfile(client_config.pidfile);
1123 /* Goes to stdout (unless NOMMU) and possibly syslog */
1124 bb_info_msg("%s (v"BB_VER") started", applet_name);
1125 /* Set up the signal pipe */
1126 udhcp_sp_setup();
1127 /* We want random_xid to be random... */
1128 srand(monotonic_us());
1129
1130 state = INIT_SELECTING;
1131 udhcp_run_script(NULL, "deconfig");
1132 change_listen_mode(LISTEN_RAW);
1133 packet_num = 0;
1134 timeout = 0;
1135 already_waited_sec = 0;
1136
1137 /* Main event loop. select() waits on signal pipe and possibly
1138 * on sockfd.
1139 * "continue" statements in code below jump to the top of the loop.
1140 */
1141 for (;;) {
1142 /* silence "uninitialized!" warning */
1143 unsigned timestamp_before_wait = timestamp_before_wait;
1144
1145 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1146
1147 /* Was opening raw or udp socket here
1148 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1149 * but on fast network renew responses return faster
1150 * than we open sockets. Thus this code is moved
1151 * to change_listen_mode(). Thus we open listen socket
1152 * BEFORE we send renew request (see "case BOUND:"). */
1153
1154 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1155
1156 tv.tv_sec = timeout - already_waited_sec;
1157 tv.tv_usec = 0;
1158 retval = 0;
1159 /* If we already timed out, fall through with retval = 0, else... */
1160 if ((int)tv.tv_sec > 0) {
1161 timestamp_before_wait = (unsigned)monotonic_sec();
1162 log1("Waiting on select...");
1163 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1164 if (retval < 0) {
1165 /* EINTR? A signal was caught, don't panic */
1166 if (errno == EINTR) {
1167 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1168 continue;
1169 }
1170 /* Else: an error occured, panic! */
1171 bb_perror_msg_and_die("select");
1172 }
1173 }
1174
1175 /* If timeout dropped to zero, time to become active:
1176 * resend discover/renew/whatever
1177 */
1178 if (retval == 0) {
1179 /* When running on a bridge, the ifindex may have changed
1180 * (e.g. if member interfaces were added/removed
1181 * or if the status of the bridge changed).
1182 * Refresh ifindex and client_mac:
1183 */
1184 if (udhcp_read_interface(client_config.interface,
1185 &client_config.ifindex,
1186 NULL,
1187 client_config.client_mac)
1188 ) {
1189 return 1; /* iface is gone? */
1190 }
1191 if (clientid_mac_ptr)
1192 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1193
1194 /* We will restart the wait in any case */
1195 already_waited_sec = 0;
1196
1197 switch (state) {
1198 case INIT_SELECTING:
1199 if (packet_num < discover_retries) {
1200 if (packet_num == 0)
1201 xid = random_xid();
1202 /* broadcast */
1203 send_discover(xid, requested_ip);
1204 timeout = discover_timeout;
1205 packet_num++;
1206 continue;
1207 }
1208 leasefail:
1209 udhcp_run_script(NULL, "leasefail");
1210#if BB_MMU /* -b is not supported on NOMMU */
1211 if (opt & OPT_b) { /* background if no lease */
1212 bb_info_msg("No lease, forking to background");
1213 client_background();
1214 /* do not background again! */
1215 opt = ((opt & ~OPT_b) | OPT_f);
1216 } else
1217#endif
1218 if (opt & OPT_n) { /* abort if no lease */
1219 bb_info_msg("No lease, failing");
1220 retval = 1;
1221 goto ret;
1222 }
1223 /* wait before trying again */
1224 timeout = tryagain_timeout;
1225 packet_num = 0;
1226 continue;
1227 case REQUESTING:
1228 if (packet_num < discover_retries) {
1229 /* send broadcast select packet */
1230 send_select(xid, server_addr, requested_ip);
1231 timeout = discover_timeout;
1232 packet_num++;
1233 continue;
1234 }
1235 /* Timed out, go back to init state.
1236 * "discover...select...discover..." loops
1237 * were seen in the wild. Treat them similarly
1238 * to "no response to discover" case */
1239 change_listen_mode(LISTEN_RAW);
1240 state = INIT_SELECTING;
1241 goto leasefail;
1242 case BOUND:
1243 /* 1/2 lease passed, enter renewing state */
1244 state = RENEWING;
1245 change_listen_mode(LISTEN_KERNEL);
1246 log1("Entering renew state");
1247 /* fall right through */
1248 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1249 case_RENEW_REQUESTED:
1250 case RENEWING:
1251 if (timeout > 60) {
1252 /* send an unicast renew request */
1253 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1254 * a new UDP socket for sending inside send_renew.
1255 * I hazard to guess existing listening socket
1256 * is somehow conflicting with it, but why is it
1257 * not deterministic then?! Strange.
1258 * Anyway, it does recover by eventually failing through
1259 * into INIT_SELECTING state.
1260 */
1261 send_renew(xid, server_addr, requested_ip);
1262 timeout >>= 1;
1263 continue;
1264 }
1265 /* Timed out, enter rebinding state */
1266 log1("Entering rebinding state");
1267 state = REBINDING;
1268 /* fall right through */
1269 case REBINDING:
1270 /* Switch to bcast receive */
1271 change_listen_mode(LISTEN_RAW);
1272 /* Lease is *really* about to run out,
1273 * try to find DHCP server using broadcast */
1274 if (timeout > 0) {
1275 /* send a broadcast renew request */
1276 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1277 timeout >>= 1;
1278 continue;
1279 }
1280 /* Timed out, enter init state */
1281 bb_info_msg("Lease lost, entering init state");
1282 udhcp_run_script(NULL, "deconfig");
1283 state = INIT_SELECTING;
1284 /*timeout = 0; - already is */
1285 packet_num = 0;
1286 continue;
1287 /* case RELEASED: */
1288 }
1289 /* yah, I know, *you* say it would never happen */
1290 timeout = INT_MAX;
1291 continue; /* back to main loop */
1292 } /* if select timed out */
1293
1294 /* select() didn't timeout, something happened */
1295
1296 /* Is it a signal? */
1297 /* note: udhcp_sp_read checks FD_ISSET before reading */
1298 switch (udhcp_sp_read(&rfds)) {
1299 case SIGUSR1:
1300 perform_renew();
1301 if (state == RENEW_REQUESTED)
1302 goto case_RENEW_REQUESTED;
1303 /* Start things over */
1304 packet_num = 0;
1305 /* Kill any timeouts, user wants this to hurry along */
1306 timeout = 0;
1307 continue;
1308 case SIGUSR2:
1309 perform_release(requested_ip, server_addr);
1310 timeout = INT_MAX;
1311 continue;
1312 case SIGTERM:
1313 bb_info_msg("Received SIGTERM");
1314 if (opt & OPT_R) /* release on quit */
1315 perform_release(requested_ip, server_addr);
1316 goto ret0;
1317 }
1318
1319 /* Is it a packet? */
1320 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1321 continue; /* no */
1322
1323 {
1324 int len;
1325
1326 /* A packet is ready, read it */
1327 if (listen_mode == LISTEN_KERNEL)
1328 len = udhcp_recv_kernel_packet(&packet, sockfd);
1329 else
1330 len = udhcp_recv_raw_packet(&packet, sockfd);
1331 if (len == -1) {
1332 /* Error is severe, reopen socket */
1333 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1334 sleep(discover_timeout); /* 3 seconds by default */
1335 change_listen_mode(listen_mode); /* just close and reopen */
1336 }
1337 /* If this packet will turn out to be unrelated/bogus,
1338 * we will go back and wait for next one.
1339 * Be sure timeout is properly decreased. */
1340 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1341 if (len < 0)
1342 continue;
1343 }
1344
1345 if (packet.xid != xid) {
1346 log1("xid %x (our is %x), ignoring packet",
1347 (unsigned)packet.xid, (unsigned)xid);
1348 continue;
1349 }
1350
1351 /* Ignore packets that aren't for us */
1352 if (packet.hlen != 6
1353 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1354 ) {
1355//FIXME: need to also check that last 10 bytes are zero
1356 log1("chaddr does not match, ignoring packet"); // log2?
1357 continue;
1358 }
1359
1360 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1361 if (message == NULL) {
1362 bb_error_msg("no message type option, ignoring packet");
1363 continue;
1364 }
1365
1366 switch (state) {
1367 case INIT_SELECTING:
1368 /* Must be a DHCPOFFER to one of our xid's */
1369 if (*message == DHCPOFFER) {
1370 /* TODO: why we don't just fetch server's IP from IP header? */
1371 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1372 if (!temp) {
1373 bb_error_msg("no server ID, ignoring packet");
1374 continue;
1375 /* still selecting - this server looks bad */
1376 }
1377 /* it IS unaligned sometimes, don't "optimize" */
1378 move_from_unaligned32(server_addr, temp);
1379 /*xid = packet.xid; - already is */
1380 requested_ip = packet.yiaddr;
1381
1382 /* enter requesting state */
1383 state = REQUESTING;
1384 timeout = 0;
1385 packet_num = 0;
1386 already_waited_sec = 0;
1387 }
1388 continue;
1389 case REQUESTING:
1390 case RENEWING:
1391 case RENEW_REQUESTED:
1392 case REBINDING:
1393 if (*message == DHCPACK) {
1394 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1395 if (!temp) {
1396 bb_error_msg("no lease time with ACK, using 1 hour lease");
1397 lease_seconds = 60 * 60;
1398 } else {
1399 /* it IS unaligned sometimes, don't "optimize" */
1400 move_from_unaligned32(lease_seconds, temp);
1401 lease_seconds = ntohl(lease_seconds);
1402 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1403 if (lease_seconds < 10) /* and not too small */
1404 lease_seconds = 10;
1405 }
1406#if ENABLE_FEATURE_UDHCPC_ARPING
1407 if (opt & OPT_a) {
1408/* RFC 2131 3.1 paragraph 5:
1409 * "The client receives the DHCPACK message with configuration
1410 * parameters. The client SHOULD perform a final check on the
1411 * parameters (e.g., ARP for allocated network address), and notes
1412 * the duration of the lease specified in the DHCPACK message. At this
1413 * point, the client is configured. If the client detects that the
1414 * address is already in use (e.g., through the use of ARP),
1415 * the client MUST send a DHCPDECLINE message to the server and restarts
1416 * the configuration process..." */
1417 if (!arpping(packet.yiaddr,
1418 NULL,
1419 (uint32_t) 0,
1420 client_config.client_mac,
1421 client_config.interface)
1422 ) {
1423 bb_info_msg("Offered address is in use "
1424 "(got ARP reply), declining");
1425 send_decline(xid, server_addr, packet.yiaddr);
1426
1427 if (state != REQUESTING)
1428 udhcp_run_script(NULL, "deconfig");
1429 change_listen_mode(LISTEN_RAW);
1430 state = INIT_SELECTING;
1431 requested_ip = 0;
1432 timeout = tryagain_timeout;
1433 packet_num = 0;
1434 already_waited_sec = 0;
1435 continue; /* back to main loop */
1436 }
1437 }
1438#endif
1439 /* enter bound state */
1440 timeout = lease_seconds / 2;
1441 {
1442 struct in_addr temp_addr;
1443 temp_addr.s_addr = packet.yiaddr;
1444 bb_info_msg("Lease of %s obtained, lease time %u",
1445 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1446 }
1447 requested_ip = packet.yiaddr;
1448 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1449
1450 state = BOUND;
1451 change_listen_mode(LISTEN_NONE);
1452 if (opt & OPT_q) { /* quit after lease */
1453 if (opt & OPT_R) /* release on quit */
1454 perform_release(requested_ip, server_addr);
1455 goto ret0;
1456 }
1457 /* future renew failures should not exit (JM) */
1458 opt &= ~OPT_n;
1459#if BB_MMU /* NOMMU case backgrounded earlier */
1460 if (!(opt & OPT_f)) {
1461 client_background();
1462 /* do not background again! */
1463 opt = ((opt & ~OPT_b) | OPT_f);
1464 }
1465#endif
1466 already_waited_sec = 0;
1467 continue; /* back to main loop */
1468 }
1469 if (*message == DHCPNAK) {
1470 /* return to init state */
1471 bb_info_msg("Received DHCP NAK");
1472 udhcp_run_script(&packet, "nak");
1473 if (state != REQUESTING)
1474 udhcp_run_script(NULL, "deconfig");
1475 change_listen_mode(LISTEN_RAW);
1476 sleep(3); /* avoid excessive network traffic */
1477 state = INIT_SELECTING;
1478 requested_ip = 0;
1479 timeout = 0;
1480 packet_num = 0;
1481 already_waited_sec = 0;
1482 }
1483 continue;
1484 /* case BOUND: - ignore all packets */
1485 /* case RELEASED: - ignore all packets */
1486 }
1487 /* back to main loop */
1488 } /* for (;;) - main loop ends */
1489
1490 ret0:
1491 retval = 0;
1492 ret:
1493 /*if (client_config.pidfile) - remove_pidfile has its own check */
1494 remove_pidfile(client_config.pidfile);
1495 return retval;
1496}
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