source: MondoRescue/branches/3.3/mindi-busybox/networking/udhcp/dhcpc.c@ 3621

Last change on this file since 3621 was 3621, checked in by Bruno Cornec, 7 years ago

New 3?3 banch for incorporation of latest busybox 1.25. Changing minor version to handle potential incompatibilities.
File size: 57.2 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 <netinet/if_ether.h>
29#include <linux/filter.h>
30#include <linux/if_packet.h>
31
32#ifndef PACKET_AUXDATA
33# define PACKET_AUXDATA 8
34struct tpacket_auxdata {
35 uint32_t tp_status;
36 uint32_t tp_len;
37 uint32_t tp_snaplen;
38 uint16_t tp_mac;
39 uint16_t tp_net;
40 uint16_t tp_vlan_tci;
41 uint16_t tp_padding;
42};
43#endif
44
45
46/* "struct client_config_t client_config" is in bb_common_bufsiz1 */
47
48
49#if ENABLE_LONG_OPTS
50static const char udhcpc_longopts[] ALIGN1 =
51 "clientid-none\0" No_argument "C"
52 "vendorclass\0" Required_argument "V"
53 "hostname\0" Required_argument "H"
54 "fqdn\0" Required_argument "F"
55 "interface\0" Required_argument "i"
56 "now\0" No_argument "n"
57 "pidfile\0" Required_argument "p"
58 "quit\0" No_argument "q"
59 "release\0" No_argument "R"
60 "request\0" Required_argument "r"
61 "script\0" Required_argument "s"
62 "timeout\0" Required_argument "T"
63 "retries\0" Required_argument "t"
64 "tryagain\0" Required_argument "A"
65 "syslog\0" No_argument "S"
66 "request-option\0" Required_argument "O"
67 "no-default-options\0" No_argument "o"
68 "foreground\0" No_argument "f"
69 "background\0" No_argument "b"
70 "broadcast\0" No_argument "B"
71 IF_FEATURE_UDHCPC_ARPING("arping\0" Optional_argument "a")
72 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
73 ;
74#endif
75/* Must match getopt32 option string order */
76enum {
77 OPT_C = 1 << 0,
78 OPT_V = 1 << 1,
79 OPT_H = 1 << 2,
80 OPT_h = 1 << 3,
81 OPT_F = 1 << 4,
82 OPT_i = 1 << 5,
83 OPT_n = 1 << 6,
84 OPT_p = 1 << 7,
85 OPT_q = 1 << 8,
86 OPT_R = 1 << 9,
87 OPT_r = 1 << 10,
88 OPT_s = 1 << 11,
89 OPT_T = 1 << 12,
90 OPT_t = 1 << 13,
91 OPT_S = 1 << 14,
92 OPT_A = 1 << 15,
93 OPT_O = 1 << 16,
94 OPT_o = 1 << 17,
95 OPT_x = 1 << 18,
96 OPT_f = 1 << 19,
97 OPT_B = 1 << 20,
98/* The rest has variable bit positions, need to be clever */
99 OPTBIT_B = 20,
100 USE_FOR_MMU( OPTBIT_b,)
101 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
102 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
103 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
104 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
105 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
106};
107
108
109/*** Script execution code ***/
110
111/* get a rough idea of how long an option will be (rounding up...) */
112static const uint8_t len_of_option_as_string[] ALIGN1 = {
113 [OPTION_IP ] = sizeof("255.255.255.255 "),
114 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
115 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
116 [OPTION_6RD ] = sizeof("132 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
117 [OPTION_STRING ] = 1,
118 [OPTION_STRING_HOST ] = 1,
119#if ENABLE_FEATURE_UDHCP_RFC3397
120 [OPTION_DNS_STRING ] = 1, /* unused */
121 /* Hmmm, this severely overestimates size if SIP_SERVERS option
122 * is in domain name form: N-byte option in binary form
123 * mallocs ~16*N bytes. But it is freed almost at once.
124 */
125 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
126#endif
127// [OPTION_BOOLEAN ] = sizeof("yes "),
128 [OPTION_U8 ] = sizeof("255 "),
129 [OPTION_U16 ] = sizeof("65535 "),
130// [OPTION_S16 ] = sizeof("-32768 "),
131 [OPTION_U32 ] = sizeof("4294967295 "),
132 [OPTION_S32 ] = sizeof("-2147483684 "),
133};
134
135/* note: ip is a pointer to an IP in network order, possibly misaliged */
136static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
137{
138 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
139}
140
141/* really simple implementation, just count the bits */
142static int mton(uint32_t mask)
143{
144 int i = 0;
145 mask = ntohl(mask); /* 111110000-like bit pattern */
146 while (mask) {
147 i++;
148 mask <<= 1;
149 }
150 return i;
151}
152
153#if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
154/* Check if a given label represents a valid DNS label
155 * Return pointer to the first character after the label upon success,
156 * NULL otherwise.
157 * See RFC1035, 2.3.1
158 */
159/* We don't need to be particularly anal. For example, allowing _, hyphen
160 * at the end, or leading and trailing dots would be ok, since it
161 * can't be used for attacks. (Leading hyphen can be, if someone uses
162 * cmd "$hostname"
163 * in the script: then hostname may be treated as an option)
164 */
165static const char *valid_domain_label(const char *label)
166{
167 unsigned char ch;
168 unsigned pos = 0;
169
170 for (;;) {
171 ch = *label;
172 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
173 if (ch < '0' || ch > '9') {
174 if (ch == '\0' || ch == '.')
175 return label;
176 /* DNS allows only '-', but we are more permissive */
177 if (ch != '-' && ch != '_')
178 return NULL;
179 }
180 }
181 label++;
182 pos++;
183 //Do we want this?
184 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
185 // return NULL;
186 }
187}
188
189/* Check if a given name represents a valid DNS name */
190/* See RFC1035, 2.3.1 */
191static int good_hostname(const char *name)
192{
193 //const char *start = name;
194
195 for (;;) {
196 name = valid_domain_label(name);
197 if (!name)
198 return 0;
199 if (!name[0])
200 return 1;
201 //Do we want this?
202 //return ((name - start) < 1025); /* NS_MAXDNAME */
203 name++;
204 if (*name == '\0')
205 return 1; // We allow trailing dot too
206 }
207}
208#else
209# define good_hostname(name) 1
210#endif
211
212/* Create "opt_name=opt_value" string */
213static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
214{
215 unsigned upper_length;
216 int len, type, optlen;
217 char *dest, *ret;
218
219 /* option points to OPT_DATA, need to go back to get OPT_LEN */
220 len = option[-OPT_DATA + OPT_LEN];
221
222 type = optflag->flags & OPTION_TYPE_MASK;
223 optlen = dhcp_option_lengths[type];
224 upper_length = len_of_option_as_string[type]
225 * ((unsigned)(len + optlen) / (unsigned)optlen);
226
227 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
228 dest += sprintf(ret, "%s=", opt_name);
229
230 while (len >= optlen) {
231 switch (type) {
232 case OPTION_IP:
233 case OPTION_IP_PAIR:
234 dest += sprint_nip(dest, "", option);
235 if (type == OPTION_IP)
236 break;
237 dest += sprint_nip(dest, "/", option + 4);
238 break;
239// case OPTION_BOOLEAN:
240// dest += sprintf(dest, *option ? "yes" : "no");
241// break;
242 case OPTION_U8:
243 dest += sprintf(dest, "%u", *option);
244 break;
245// case OPTION_S16:
246 case OPTION_U16: {
247 uint16_t val_u16;
248 move_from_unaligned16(val_u16, option);
249 dest += sprintf(dest, "%u", ntohs(val_u16));
250 break;
251 }
252 case OPTION_S32:
253 case OPTION_U32: {
254 uint32_t val_u32;
255 move_from_unaligned32(val_u32, option);
256 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
257 break;
258 }
259 /* Note: options which use 'return' instead of 'break'
260 * (for example, OPTION_STRING) skip the code which handles
261 * the case of list of options.
262 */
263 case OPTION_STRING:
264 case OPTION_STRING_HOST:
265 memcpy(dest, option, len);
266 dest[len] = '\0';
267 if (type == OPTION_STRING_HOST && !good_hostname(dest))
268 safe_strncpy(dest, "bad", len);
269 return ret;
270 case OPTION_STATIC_ROUTES: {
271 /* Option binary format:
272 * mask [one byte, 0..32]
273 * ip [big endian, 0..4 bytes depending on mask]
274 * router [big endian, 4 bytes]
275 * may be repeated
276 *
277 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
278 */
279 const char *pfx = "";
280
281 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
282 uint32_t nip;
283 uint8_t *p;
284 unsigned mask;
285 int bytes;
286
287 mask = *option++;
288 if (mask > 32)
289 break;
290 len--;
291
292 nip = 0;
293 p = (void*) &nip;
294 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
295 while (--bytes >= 0) {
296 *p++ = *option++;
297 len--;
298 }
299 if (len < 4)
300 break;
301
302 /* print ip/mask */
303 dest += sprint_nip(dest, pfx, (void*) &nip);
304 pfx = " ";
305 dest += sprintf(dest, "/%u ", mask);
306 /* print router */
307 dest += sprint_nip(dest, "", option);
308 option += 4;
309 len -= 4;
310 }
311
312 return ret;
313 }
314 case OPTION_6RD:
315 /* Option binary format (see RFC 5969):
316 * 0 1 2 3
317 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
318 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
319 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
320 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
321 * | 6rdPrefix |
322 * ... (16 octets) ...
323 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
324 * ... 6rdBRIPv4Address(es) ...
325 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
326 * We convert it to a string
327 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
328 *
329 * Sanity check: ensure that our length is at least 22 bytes, that
330 * IPv4MaskLen <= 32,
331 * 6rdPrefixLen <= 128,
332 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
333 * (2nd condition need no check - it follows from 1st and 3rd).
334 * Else, return envvar with empty value ("optname=")
335 */
336 if (len >= (1 + 1 + 16 + 4)
337 && option[0] <= 32
338 && (option[1] + 32 - option[0]) <= 128
339 ) {
340 /* IPv4MaskLen */
341 dest += sprintf(dest, "%u ", *option++);
342 /* 6rdPrefixLen */
343 dest += sprintf(dest, "%u ", *option++);
344 /* 6rdPrefix */
345 dest += sprint_nip6(dest, /* "", */ option);
346 option += 16;
347 len -= 1 + 1 + 16 + 4;
348 /* "+ 4" above corresponds to the length of IPv4 addr
349 * we consume in the loop below */
350 while (1) {
351 /* 6rdBRIPv4Address(es) */
352 dest += sprint_nip(dest, " ", option);
353 option += 4;
354 len -= 4; /* do we have yet another 4+ bytes? */
355 if (len < 0)
356 break; /* no */
357 }
358 }
359
360 return ret;
361#if ENABLE_FEATURE_UDHCP_RFC3397
362 case OPTION_DNS_STRING:
363 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
364 dest = dname_dec(option, len, ret);
365 if (dest) {
366 free(ret);
367 return dest;
368 }
369 /* error. return "optname=" string */
370 return ret;
371 case OPTION_SIP_SERVERS:
372 /* Option binary format:
373 * type: byte
374 * type=0: domain names, dns-compressed
375 * type=1: IP addrs
376 */
377 option++;
378 len--;
379 if (option[-1] == 0) {
380 dest = dname_dec(option, len, ret);
381 if (dest) {
382 free(ret);
383 return dest;
384 }
385 } else
386 if (option[-1] == 1) {
387 const char *pfx = "";
388 while (1) {
389 len -= 4;
390 if (len < 0)
391 break;
392 dest += sprint_nip(dest, pfx, option);
393 pfx = " ";
394 option += 4;
395 }
396 }
397 return ret;
398#endif
399 } /* switch */
400
401 /* If we are here, try to format any remaining data
402 * in the option as another, similarly-formatted option
403 */
404 option += optlen;
405 len -= optlen;
406// TODO: it can be a list only if (optflag->flags & OPTION_LIST).
407// Should we bail out/warn if we see multi-ip option which is
408// not allowed to be such (for example, DHCP_BROADCAST)? -
409 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
410 break;
411 *dest++ = ' ';
412 *dest = '\0';
413 } /* while */
414
415 return ret;
416}
417
418/* put all the parameters into the environment */
419static char **fill_envp(struct dhcp_packet *packet)
420{
421 int envc;
422 int i;
423 char **envp, **curr;
424 const char *opt_name;
425 uint8_t *temp;
426 uint8_t overload = 0;
427
428#define BITMAP unsigned
429#define BBITS (sizeof(BITMAP) * 8)
430#define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
431#define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
432 BITMAP found_opts[256 / BBITS];
433
434 memset(found_opts, 0, sizeof(found_opts));
435
436 /* We need 6 elements for:
437 * "interface=IFACE"
438 * "ip=N.N.N.N" from packet->yiaddr
439 * "siaddr=IP" from packet->siaddr_nip (unless 0)
440 * "boot_file=FILE" from packet->file (unless overloaded)
441 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
442 * terminating NULL
443 */
444 envc = 6;
445 /* +1 element for each option, +2 for subnet option: */
446 if (packet) {
447 /* note: do not search for "pad" (0) and "end" (255) options */
448//TODO: change logic to scan packet _once_
449 for (i = 1; i < 255; i++) {
450 temp = udhcp_get_option(packet, i);
451 if (temp) {
452 if (i == DHCP_OPTION_OVERLOAD)
453 overload = *temp;
454 else if (i == DHCP_SUBNET)
455 envc++; /* for $mask */
456 envc++;
457 /*if (i != DHCP_MESSAGE_TYPE)*/
458 FOUND_OPTS(i) |= BMASK(i);
459 }
460 }
461 }
462 curr = envp = xzalloc(sizeof(envp[0]) * envc);
463
464 *curr = xasprintf("interface=%s", client_config.interface);
465 putenv(*curr++);
466
467 if (!packet)
468 return envp;
469
470 /* Export BOOTP fields. Fields we don't (yet?) export:
471 * uint8_t op; // always BOOTREPLY
472 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
473 * uint8_t hlen; // hardware address length
474 * uint8_t hops; // used by relay agents only
475 * uint32_t xid;
476 * uint16_t secs; // elapsed since client began acquisition/renewal
477 * uint16_t flags; // only one flag so far: bcast. Never set by server
478 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
479 * // if during renew server wants to give us differn IP?)
480 * uint32_t gateway_nip; // relay agent IP address
481 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
482 * TODO: export gateway_nip as $giaddr?
483 */
484 /* Most important one: yiaddr as $ip */
485 *curr = xmalloc(sizeof("ip=255.255.255.255"));
486 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
487 putenv(*curr++);
488 if (packet->siaddr_nip) {
489 /* IP address of next server to use in bootstrap */
490 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
491 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
492 putenv(*curr++);
493 }
494 if (!(overload & FILE_FIELD) && packet->file[0]) {
495 /* watch out for invalid packets */
496 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
497 putenv(*curr++);
498 }
499 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
500 /* watch out for invalid packets */
501 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
502 putenv(*curr++);
503 }
504
505 /* Export known DHCP options */
506 opt_name = dhcp_option_strings;
507 i = 0;
508 while (*opt_name) {
509 uint8_t code = dhcp_optflags[i].code;
510 BITMAP *found_ptr = &FOUND_OPTS(code);
511 BITMAP found_mask = BMASK(code);
512 if (!(*found_ptr & found_mask))
513 goto next;
514 *found_ptr &= ~found_mask; /* leave only unknown options */
515 temp = udhcp_get_option(packet, code);
516 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
517 putenv(*curr++);
518 if (code == DHCP_SUBNET) {
519 /* Subnet option: make things like "$ip/$mask" possible */
520 uint32_t subnet;
521 move_from_unaligned32(subnet, temp);
522 *curr = xasprintf("mask=%u", mton(subnet));
523 putenv(*curr++);
524 }
525 next:
526 opt_name += strlen(opt_name) + 1;
527 i++;
528 }
529 /* Export unknown options */
530 for (i = 0; i < 256;) {
531 BITMAP bitmap = FOUND_OPTS(i);
532 if (!bitmap) {
533 i += BBITS;
534 continue;
535 }
536 if (bitmap & BMASK(i)) {
537 unsigned len, ofs;
538
539 temp = udhcp_get_option(packet, i);
540 /* udhcp_get_option returns ptr to data portion,
541 * need to go back to get len
542 */
543 len = temp[-OPT_DATA + OPT_LEN];
544 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
545 ofs = sprintf(*curr, "opt%u=", i);
546 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
547 putenv(*curr++);
548 }
549 i++;
550 }
551
552 return envp;
553}
554
555/* Call a script with a par file and env vars */
556static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
557{
558 char **envp, **curr;
559 char *argv[3];
560
561 envp = fill_envp(packet);
562
563 /* call script */
564 log1("executing %s %s", client_config.script, name);
565 argv[0] = (char*) client_config.script;
566 argv[1] = (char*) name;
567 argv[2] = NULL;
568 spawn_and_wait(argv);
569
570 for (curr = envp; *curr; curr++) {
571 log2(" %s", *curr);
572 bb_unsetenv_and_free(*curr);
573 }
574 free(envp);
575}
576
577
578/*** Sending/receiving packets ***/
579
580static ALWAYS_INLINE uint32_t random_xid(void)
581{
582 return rand();
583}
584
585/* Initialize the packet with the proper defaults */
586static void init_packet(struct dhcp_packet *packet, char type)
587{
588 uint16_t secs;
589
590 /* Fill in: op, htype, hlen, cookie fields; message type option: */
591 udhcp_init_header(packet, type);
592
593 packet->xid = random_xid();
594
595 client_config.last_secs = monotonic_sec();
596 if (client_config.first_secs == 0)
597 client_config.first_secs = client_config.last_secs;
598 secs = client_config.last_secs - client_config.first_secs;
599 packet->secs = htons(secs);
600
601 memcpy(packet->chaddr, client_config.client_mac, 6);
602 if (client_config.clientid)
603 udhcp_add_binary_option(packet, client_config.clientid);
604}
605
606static void add_client_options(struct dhcp_packet *packet)
607{
608 int i, end, len;
609
610 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
611
612 /* Add a "param req" option with the list of options we'd like to have
613 * from stubborn DHCP servers. Pull the data from the struct in common.c.
614 * No bounds checking because it goes towards the head of the packet. */
615 end = udhcp_end_option(packet->options);
616 len = 0;
617 for (i = 1; i < DHCP_END; i++) {
618 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
619 packet->options[end + OPT_DATA + len] = i;
620 len++;
621 }
622 }
623 if (len) {
624 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
625 packet->options[end + OPT_LEN] = len;
626 packet->options[end + OPT_DATA + len] = DHCP_END;
627 }
628
629 if (client_config.vendorclass)
630 udhcp_add_binary_option(packet, client_config.vendorclass);
631 if (client_config.hostname)
632 udhcp_add_binary_option(packet, client_config.hostname);
633 if (client_config.fqdn)
634 udhcp_add_binary_option(packet, client_config.fqdn);
635
636 /* Request broadcast replies if we have no IP addr */
637 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
638 packet->flags |= htons(BROADCAST_FLAG);
639
640 /* Add -x options if any */
641 {
642 struct option_set *curr = client_config.options;
643 while (curr) {
644 udhcp_add_binary_option(packet, curr->data);
645 curr = curr->next;
646 }
647// if (client_config.sname)
648// strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
649// if (client_config.boot_file)
650// strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
651 }
652
653 // This will be needed if we remove -V VENDOR_STR in favor of
654 // -x vendor:VENDOR_STR
655 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
656 // /* not set, set the default vendor ID */
657 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
658}
659
660/* RFC 2131
661 * 4.4.4 Use of broadcast and unicast
662 *
663 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
664 * messages, unless the client knows the address of a DHCP server.
665 * The client unicasts DHCPRELEASE messages to the server. Because
666 * the client is declining the use of the IP address supplied by the server,
667 * the client broadcasts DHCPDECLINE messages.
668 *
669 * When the DHCP client knows the address of a DHCP server, in either
670 * INIT or REBOOTING state, the client may use that address
671 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
672 * The client may also use unicast to send DHCPINFORM messages
673 * to a known DHCP server. If the client receives no response to DHCP
674 * messages sent to the IP address of a known DHCP server, the DHCP
675 * client reverts to using the IP broadcast address.
676 */
677
678static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet, uint32_t src_nip)
679{
680 return udhcp_send_raw_packet(packet,
681 /*src*/ src_nip, CLIENT_PORT,
682 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
683 client_config.ifindex);
684}
685
686static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
687{
688 if (server)
689 return udhcp_send_kernel_packet(packet,
690 ciaddr, CLIENT_PORT,
691 server, SERVER_PORT);
692 return raw_bcast_from_client_config_ifindex(packet, ciaddr);
693}
694
695/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
696/* NOINLINE: limit stack usage in caller */
697static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
698{
699 struct dhcp_packet packet;
700
701 /* Fill in: op, htype, hlen, cookie, chaddr fields,
702 * random xid field (we override it below),
703 * client-id option (unless -C), message type option:
704 */
705 init_packet(&packet, DHCPDISCOVER);
706
707 packet.xid = xid;
708 if (requested)
709 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
710
711 /* Add options: maxsize,
712 * optionally: hostname, fqdn, vendorclass,
713 * "param req" option according to -O, options specified with -x
714 */
715 add_client_options(&packet);
716
717 bb_error_msg("sending %s", "discover");
718 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
719}
720
721/* Broadcast a DHCP request message */
722/* RFC 2131 3.1 paragraph 3:
723 * "The client _broadcasts_ a DHCPREQUEST message..."
724 */
725/* NOINLINE: limit stack usage in caller */
726static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
727{
728 struct dhcp_packet packet;
729 struct in_addr addr;
730
731/*
732 * RFC 2131 4.3.2 DHCPREQUEST message
733 * ...
734 * If the DHCPREQUEST message contains a 'server identifier'
735 * option, the message is in response to a DHCPOFFER message.
736 * Otherwise, the message is a request to verify or extend an
737 * existing lease. If the client uses a 'client identifier'
738 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
739 * in all subsequent messages. If the client included a list
740 * of requested parameters in a DHCPDISCOVER message, it MUST
741 * include that list in all subsequent messages.
742 */
743 /* Fill in: op, htype, hlen, cookie, chaddr fields,
744 * random xid field (we override it below),
745 * client-id option (unless -C), message type option:
746 */
747 init_packet(&packet, DHCPREQUEST);
748
749 packet.xid = xid;
750 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
751
752 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
753
754 /* Add options: maxsize,
755 * optionally: hostname, fqdn, vendorclass,
756 * "param req" option according to -O, and options specified with -x
757 */
758 add_client_options(&packet);
759
760 addr.s_addr = requested;
761 bb_error_msg("sending select for %s", inet_ntoa(addr));
762 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
763}
764
765/* Unicast or broadcast a DHCP renew message */
766/* NOINLINE: limit stack usage in caller */
767static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
768{
769 struct dhcp_packet packet;
770
771/*
772 * RFC 2131 4.3.2 DHCPREQUEST message
773 * ...
774 * DHCPREQUEST generated during RENEWING state:
775 *
776 * 'server identifier' MUST NOT be filled in, 'requested IP address'
777 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
778 * client's IP address. In this situation, the client is completely
779 * configured, and is trying to extend its lease. This message will
780 * be unicast, so no relay agents will be involved in its
781 * transmission. Because 'giaddr' is therefore not filled in, the
782 * DHCP server will trust the value in 'ciaddr', and use it when
783 * replying to the client.
784 */
785 /* Fill in: op, htype, hlen, cookie, chaddr fields,
786 * random xid field (we override it below),
787 * client-id option (unless -C), message type option:
788 */
789 init_packet(&packet, DHCPREQUEST);
790
791 packet.xid = xid;
792 packet.ciaddr = ciaddr;
793
794 /* Add options: maxsize,
795 * optionally: hostname, fqdn, vendorclass,
796 * "param req" option according to -O, and options specified with -x
797 */
798 add_client_options(&packet);
799
800 bb_error_msg("sending %s", "renew");
801 return bcast_or_ucast(&packet, ciaddr, server);
802}
803
804#if ENABLE_FEATURE_UDHCPC_ARPING
805/* Broadcast a DHCP decline message */
806/* NOINLINE: limit stack usage in caller */
807static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
808{
809 struct dhcp_packet packet;
810
811 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
812 * client-id option (unless -C), message type option:
813 */
814 init_packet(&packet, DHCPDECLINE);
815
816#if 0
817 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
818 * but in case the server is buggy and wants DHCPDECLINE's xid
819 * to match the xid which started entire handshake,
820 * we use the same xid we used in initial DHCPDISCOVER:
821 */
822 packet.xid = xid;
823#endif
824 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
825 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
826
827 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
828
829 bb_error_msg("sending %s", "decline");
830 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
831}
832#endif
833
834/* Unicast a DHCP release message */
835static int send_release(uint32_t server, uint32_t ciaddr)
836{
837 struct dhcp_packet packet;
838
839 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
840 * client-id option (unless -C), message type option:
841 */
842 init_packet(&packet, DHCPRELEASE);
843
844 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
845 packet.ciaddr = ciaddr;
846
847 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
848
849 bb_error_msg("sending %s", "release");
850 /* Note: normally we unicast here since "server" is not zero.
851 * However, there _are_ people who run "address-less" DHCP servers,
852 * and reportedly ISC dhcp client and Windows allow that.
853 */
854 return bcast_or_ucast(&packet, ciaddr, server);
855}
856
857/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
858/* NOINLINE: limit stack usage in caller */
859static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
860{
861 int bytes;
862 struct ip_udp_dhcp_packet packet;
863 uint16_t check;
864 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
865 struct iovec iov;
866 struct msghdr msg;
867 struct cmsghdr *cmsg;
868
869 /* used to use just safe_read(fd, &packet, sizeof(packet))
870 * but we need to check for TP_STATUS_CSUMNOTREADY :(
871 */
872 iov.iov_base = &packet;
873 iov.iov_len = sizeof(packet);
874 memset(&msg, 0, sizeof(msg));
875 msg.msg_iov = &iov;
876 msg.msg_iovlen = 1;
877 msg.msg_control = cmsgbuf;
878 msg.msg_controllen = sizeof(cmsgbuf);
879 for (;;) {
880 bytes = recvmsg(fd, &msg, 0);
881 if (bytes < 0) {
882 if (errno == EINTR)
883 continue;
884 log1("packet read error, ignoring");
885 /* NB: possible down interface, etc. Caller should pause. */
886 return bytes; /* returns -1 */
887 }
888 break;
889 }
890
891 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
892 log1("packet is too short, ignoring");
893 return -2;
894 }
895
896 if (bytes < ntohs(packet.ip.tot_len)) {
897 /* packet is bigger than sizeof(packet), we did partial read */
898 log1("oversized packet, ignoring");
899 return -2;
900 }
901
902 /* ignore any extra garbage bytes */
903 bytes = ntohs(packet.ip.tot_len);
904
905 /* make sure its the right packet for us, and that it passes sanity checks */
906 if (packet.ip.protocol != IPPROTO_UDP
907 || packet.ip.version != IPVERSION
908 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
909 || packet.udp.dest != htons(CLIENT_PORT)
910 /* || bytes > (int) sizeof(packet) - can't happen */
911 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
912 ) {
913 log1("unrelated/bogus packet, ignoring");
914 return -2;
915 }
916
917 /* verify IP checksum */
918 check = packet.ip.check;
919 packet.ip.check = 0;
920 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
921 log1("bad IP header checksum, ignoring");
922 return -2;
923 }
924
925 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
926 if (cmsg->cmsg_level == SOL_PACKET
927 && cmsg->cmsg_type == PACKET_AUXDATA
928 ) {
929 /* some VMs don't checksum UDP and TCP data
930 * they send to the same physical machine,
931 * here we detect this case:
932 */
933 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
934 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
935 goto skip_udp_sum_check;
936 }
937 }
938
939 /* verify UDP checksum. IP header has to be modified for this */
940 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
941 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
942 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
943 check = packet.udp.check;
944 packet.udp.check = 0;
945 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
946 log1("packet with bad UDP checksum received, ignoring");
947 return -2;
948 }
949 skip_udp_sum_check:
950
951 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
952 bb_error_msg("packet with bad magic, ignoring");
953 return -2;
954 }
955
956 log1("received %s", "a packet");
957 udhcp_dump_packet(&packet.data);
958
959 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
960 memcpy(dhcp_pkt, &packet.data, bytes);
961 return bytes;
962}
963
964
965/*** Main ***/
966
967static int sockfd = -1;
968
969#define LISTEN_NONE 0
970#define LISTEN_KERNEL 1
971#define LISTEN_RAW 2
972static smallint listen_mode;
973
974/* initial state: (re)start DHCP negotiation */
975#define INIT_SELECTING 0
976/* discover was sent, DHCPOFFER reply received */
977#define REQUESTING 1
978/* select/renew was sent, DHCPACK reply received */
979#define BOUND 2
980/* half of lease passed, want to renew it by sending unicast renew requests */
981#define RENEWING 3
982/* renew requests were not answered, lease is almost over, send broadcast renew */
983#define REBINDING 4
984/* manually requested renew (SIGUSR1) */
985#define RENEW_REQUESTED 5
986/* release, possibly manually requested (SIGUSR2) */
987#define RELEASED 6
988static smallint state;
989
990static int udhcp_raw_socket(int ifindex)
991{
992 int fd;
993 struct sockaddr_ll sock;
994
995 log1("opening raw socket on ifindex %d", ifindex); //log2?
996
997 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
998 /* ^^^^^
999 * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
1000 * ETH_P_IP: want to receive only packets with IPv4 eth type
1001 */
1002 log1("got raw socket fd"); //log2?
1003
1004 sock.sll_family = AF_PACKET;
1005 sock.sll_protocol = htons(ETH_P_IP);
1006 sock.sll_ifindex = ifindex;
1007 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
1008
1009#if 0 /* Several users reported breakage when BPF filter is used */
1010 if (CLIENT_PORT == 68) {
1011 /* Use only if standard port is in use */
1012 /*
1013 * I've selected not to see LL header, so BPF doesn't see it, too.
1014 * The filter may also pass non-IP and non-ARP packets, but we do
1015 * a more complete check when receiving the message in userspace.
1016 *
1017 * and filter shamelessly stolen from:
1018 *
1019 * http://www.flamewarmaster.de/software/dhcpclient/
1020 *
1021 * There are a few other interesting ideas on that page (look under
1022 * "Motivation"). Use of netlink events is most interesting. Think
1023 * of various network servers listening for events and reconfiguring.
1024 * That would obsolete sending HUP signals and/or make use of restarts.
1025 *
1026 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1027 * License: GPL v2.
1028 */
1029 static const struct sock_filter filter_instr[] = {
1030 /* load 9th byte (protocol) */
1031 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1032 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1033 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1034 /* L1: load halfword from offset 6 (flags and frag offset) */
1035 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1036 /* jump to L4 if any bits in frag offset field are set, else to L2 */
1037 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1038 /* L2: skip IP header (load index reg with header len) */
1039 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1040 /* load udp destination port from halfword[header_len + 2] */
1041 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1042 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1043 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1044 /* L3: accept packet ("accept 0x7fffffff bytes") */
1045 /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1046 BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1047 /* L4: discard packet ("accept zero bytes") */
1048 BPF_STMT(BPF_RET|BPF_K, 0),
1049 };
1050 static const struct sock_fprog filter_prog = {
1051 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1052 /* casting const away: */
1053 .filter = (struct sock_filter *) filter_instr,
1054 };
1055 /* Ignoring error (kernel may lack support for this) */
1056 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1057 sizeof(filter_prog)) >= 0)
1058 log1("attached filter to raw socket fd"); // log?
1059 }
1060#endif
1061
1062 if (setsockopt_1(fd, SOL_PACKET, PACKET_AUXDATA) != 0) {
1063 if (errno != ENOPROTOOPT)
1064 log1("can't set PACKET_AUXDATA on raw socket");
1065 }
1066
1067 log1("created raw socket");
1068
1069 return fd;
1070}
1071
1072static void change_listen_mode(int new_mode)
1073{
1074 log1("entering listen mode: %s",
1075 new_mode != LISTEN_NONE
1076 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1077 : "none"
1078 );
1079
1080 listen_mode = new_mode;
1081 if (sockfd >= 0) {
1082 close(sockfd);
1083 sockfd = -1;
1084 }
1085 if (new_mode == LISTEN_KERNEL)
1086 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1087 else if (new_mode != LISTEN_NONE)
1088 sockfd = udhcp_raw_socket(client_config.ifindex);
1089 /* else LISTEN_NONE: sockfd stays closed */
1090}
1091
1092/* Called only on SIGUSR1 */
1093static void perform_renew(void)
1094{
1095 bb_error_msg("performing DHCP renew");
1096 switch (state) {
1097 case BOUND:
1098 change_listen_mode(LISTEN_KERNEL);
1099 case RENEWING:
1100 case REBINDING:
1101 state = RENEW_REQUESTED;
1102 break;
1103 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1104 udhcp_run_script(NULL, "deconfig");
1105 case REQUESTING:
1106 case RELEASED:
1107 change_listen_mode(LISTEN_RAW);
1108 state = INIT_SELECTING;
1109 break;
1110 case INIT_SELECTING:
1111 break;
1112 }
1113}
1114
1115static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1116{
1117 char buffer[sizeof("255.255.255.255")];
1118 struct in_addr temp_addr;
1119
1120 /* send release packet */
1121 if (state == BOUND || state == RENEWING || state == REBINDING) {
1122 temp_addr.s_addr = server_addr;
1123 strcpy(buffer, inet_ntoa(temp_addr));
1124 temp_addr.s_addr = requested_ip;
1125 bb_error_msg("unicasting a release of %s to %s",
1126 inet_ntoa(temp_addr), buffer);
1127 send_release(server_addr, requested_ip); /* unicast */
1128 udhcp_run_script(NULL, "deconfig");
1129 }
1130 bb_error_msg("entering released state");
1131
1132 change_listen_mode(LISTEN_NONE);
1133 state = RELEASED;
1134}
1135
1136static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1137{
1138 uint8_t *storage;
1139 int len = strnlen(str, 255);
1140 storage = xzalloc(len + extra + OPT_DATA);
1141 storage[OPT_CODE] = code;
1142 storage[OPT_LEN] = len + extra;
1143 memcpy(storage + extra + OPT_DATA, str, len);
1144 return storage;
1145}
1146
1147#if BB_MMU
1148static void client_background(void)
1149{
1150 bb_daemonize(0);
1151 logmode &= ~LOGMODE_STDIO;
1152 /* rewrite pidfile, as our pid is different now */
1153 write_pidfile(client_config.pidfile);
1154}
1155#endif
1156
1157//usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1158//usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1159//usage:#else
1160//usage:# define IF_UDHCP_VERBOSE(...)
1161//usage:#endif
1162//usage:#define udhcpc_trivial_usage
1163//usage: "[-fbq"IF_UDHCP_VERBOSE("v")"RB]"IF_FEATURE_UDHCPC_ARPING(" [-a[MSEC]]")" [-t N] [-T SEC] [-A SEC/-n]\n"
1164//usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1165//usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1166//usage:#define udhcpc_full_usage "\n"
1167//usage: IF_LONG_OPTS(
1168//usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1169//usage: IF_FEATURE_UDHCP_PORT(
1170//usage: "\n -P,--client-port PORT Use PORT (default 68)"
1171//usage: )
1172//usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1173//usage: "\n -p,--pidfile FILE Create pidfile"
1174//usage: "\n -B,--broadcast Request broadcast replies"
1175//usage: "\n -t,--retries N Send up to N discover packets (default 3)"
1176//usage: "\n -T,--timeout SEC Pause between packets (default 3)"
1177//usage: "\n -A,--tryagain SEC Wait if lease is not obtained (default 20)"
1178//usage: "\n -n,--now Exit if lease is not obtained"
1179//usage: "\n -q,--quit Exit after obtaining lease"
1180//usage: "\n -R,--release Release IP on exit"
1181//usage: "\n -f,--foreground Run in foreground"
1182//usage: USE_FOR_MMU(
1183//usage: "\n -b,--background Background if lease is not obtained"
1184//usage: )
1185//usage: "\n -S,--syslog Log to syslog too"
1186//usage: IF_FEATURE_UDHCPC_ARPING(
1187//usage: "\n -a[MSEC],--arping[=MSEC] Validate offered address with ARP ping"
1188//usage: )
1189//usage: "\n -r,--request IP Request this IP address"
1190//usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1191//usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1192//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1193//usage: "\n Examples of string, numeric, and hex byte opts:"
1194//usage: "\n -x hostname:bbox - option 12"
1195//usage: "\n -x lease:3600 - option 51 (lease time)"
1196//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1197//usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1198//usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1199//usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1200//usage: IF_UDHCP_VERBOSE(
1201//usage: "\n -v Verbose"
1202//usage: )
1203//usage: )
1204//usage: IF_NOT_LONG_OPTS(
1205//usage: "\n -i IFACE Interface to use (default eth0)"
1206//usage: IF_FEATURE_UDHCP_PORT(
1207//usage: "\n -P PORT Use PORT (default 68)"
1208//usage: )
1209//usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1210//usage: "\n -p FILE Create pidfile"
1211//usage: "\n -B Request broadcast replies"
1212//usage: "\n -t N Send up to N discover packets (default 3)"
1213//usage: "\n -T SEC Pause between packets (default 3)"
1214//usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1215//usage: "\n -n Exit if lease is not obtained"
1216//usage: "\n -q Exit after obtaining lease"
1217//usage: "\n -R Release IP on exit"
1218//usage: "\n -f Run in foreground"
1219//usage: USE_FOR_MMU(
1220//usage: "\n -b Background if lease is not obtained"
1221//usage: )
1222//usage: "\n -S Log to syslog too"
1223//usage: IF_FEATURE_UDHCPC_ARPING(
1224//usage: "\n -a[MSEC] Validate offered address with ARP ping"
1225//usage: )
1226//usage: "\n -r IP Request this IP address"
1227//usage: "\n -o Don't request any options (unless -O is given)"
1228//usage: "\n -O OPT Request option OPT from server (cumulative)"
1229//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1230//usage: "\n Examples of string, numeric, and hex byte opts:"
1231//usage: "\n -x hostname:bbox - option 12"
1232//usage: "\n -x lease:3600 - option 51 (lease time)"
1233//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1234//usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1235//usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1236//usage: "\n -C Don't send MAC as client identifier"
1237//usage: IF_UDHCP_VERBOSE(
1238//usage: "\n -v Verbose"
1239//usage: )
1240//usage: )
1241//usage: "\nSignals:"
1242//usage: "\n USR1 Renew lease"
1243//usage: "\n USR2 Release lease"
1244
1245
1246int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1247int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1248{
1249 uint8_t *message;
1250 const char *str_V, *str_h, *str_F, *str_r;
1251 IF_FEATURE_UDHCPC_ARPING(const char *str_a = "2000";)
1252 IF_FEATURE_UDHCP_PORT(char *str_P;)
1253 void *clientid_mac_ptr;
1254 llist_t *list_O = NULL;
1255 llist_t *list_x = NULL;
1256 int tryagain_timeout = 20;
1257 int discover_timeout = 3;
1258 int discover_retries = 3;
1259 uint32_t server_addr = server_addr; /* for compiler */
1260 uint32_t requested_ip = 0;
1261 uint32_t xid = xid; /* for compiler */
1262 int packet_num;
1263 int timeout; /* must be signed */
1264 unsigned already_waited_sec;
1265 unsigned opt;
1266 IF_FEATURE_UDHCPC_ARPING(unsigned arpping_ms;)
1267 int max_fd;
1268 int retval;
1269 fd_set rfds;
1270
1271 setup_common_bufsiz();
1272
1273 /* Default options */
1274 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1275 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1276 client_config.interface = "eth0";
1277 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1278 str_V = "udhcp "BB_VER;
1279
1280 /* Parse command line */
1281 /* O,x: list; -T,-t,-A take numeric param */
1282 opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1283 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1284 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1285 USE_FOR_MMU("b")
1286 IF_FEATURE_UDHCPC_ARPING("a::")
1287 IF_FEATURE_UDHCP_PORT("P:")
1288 "v"
1289 , &str_V, &str_h, &str_h, &str_F
1290 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1291 , &client_config.script /* s */
1292 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1293 , &list_O
1294 , &list_x
1295 IF_FEATURE_UDHCPC_ARPING(, &str_a)
1296 IF_FEATURE_UDHCP_PORT(, &str_P)
1297 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1298 );
1299 if (opt & (OPT_h|OPT_H)) {
1300 //msg added 2011-11
1301 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1302 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1303 }
1304 if (opt & OPT_F) {
1305 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1306 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1307 /* Flag bits: 0000NEOS
1308 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1309 * O: 1 = Server indicates to client that DNS has been updated regardless
1310 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1311 * not "host.domain.com". Format 0 is obsolete.
1312 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1313 * Two [0] bytes which follow are deprecated and must be 0.
1314 */
1315 client_config.fqdn[OPT_DATA + 0] = 0x1;
1316 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1317 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1318 }
1319 if (opt & OPT_r)
1320 requested_ip = inet_addr(str_r);
1321#if ENABLE_FEATURE_UDHCP_PORT
1322 if (opt & OPT_P) {
1323 CLIENT_PORT = xatou16(str_P);
1324 SERVER_PORT = CLIENT_PORT - 1;
1325 }
1326#endif
1327 IF_FEATURE_UDHCPC_ARPING(arpping_ms = xatou(str_a);)
1328 while (list_O) {
1329 char *optstr = llist_pop(&list_O);
1330 unsigned n = bb_strtou(optstr, NULL, 0);
1331 if (errno || n > 254) {
1332 n = udhcp_option_idx(optstr);
1333 n = dhcp_optflags[n].code;
1334 }
1335 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1336 }
1337 if (!(opt & OPT_o)) {
1338 unsigned i, n;
1339 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1340 if (dhcp_optflags[i].flags & OPTION_REQ) {
1341 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1342 }
1343 }
1344 }
1345 while (list_x) {
1346 char *optstr = llist_pop(&list_x);
1347 char *colon = strchr(optstr, ':');
1348 if (colon)
1349 *colon = ' ';
1350 /* now it looks similar to udhcpd's config file line:
1351 * "optname optval", using the common routine: */
1352 udhcp_str2optset(optstr, &client_config.options);
1353 }
1354
1355 if (udhcp_read_interface(client_config.interface,
1356 &client_config.ifindex,
1357 NULL,
1358 client_config.client_mac)
1359 ) {
1360 return 1;
1361 }
1362
1363 clientid_mac_ptr = NULL;
1364 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1365 /* not suppressed and not set, set the default client ID */
1366 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1367 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1368 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1369 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1370 }
1371 if (str_V[0] != '\0') {
1372 // can drop -V, str_V, client_config.vendorclass,
1373 // but need to add "vendor" to the list of recognized
1374 // string opts for this to work;
1375 // and need to tweak add_client_options() too...
1376 // ...so the question is, should we?
1377 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1378 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1379 }
1380
1381#if !BB_MMU
1382 /* on NOMMU reexec (i.e., background) early */
1383 if (!(opt & OPT_f)) {
1384 bb_daemonize_or_rexec(0 /* flags */, argv);
1385 logmode = LOGMODE_NONE;
1386 }
1387#endif
1388 if (opt & OPT_S) {
1389 openlog(applet_name, LOG_PID, LOG_DAEMON);
1390 logmode |= LOGMODE_SYSLOG;
1391 }
1392
1393 /* Make sure fd 0,1,2 are open */
1394 bb_sanitize_stdio();
1395 /* Equivalent of doing a fflush after every \n */
1396 setlinebuf(stdout);
1397 /* Create pidfile */
1398 write_pidfile(client_config.pidfile);
1399 /* Goes to stdout (unless NOMMU) and possibly syslog */
1400 bb_error_msg("started, v"BB_VER);
1401 /* Set up the signal pipe */
1402 udhcp_sp_setup();
1403 /* We want random_xid to be random... */
1404 srand(monotonic_us());
1405
1406 state = INIT_SELECTING;
1407 udhcp_run_script(NULL, "deconfig");
1408 change_listen_mode(LISTEN_RAW);
1409 packet_num = 0;
1410 timeout = 0;
1411 already_waited_sec = 0;
1412
1413 /* Main event loop. select() waits on signal pipe and possibly
1414 * on sockfd.
1415 * "continue" statements in code below jump to the top of the loop.
1416 */
1417 for (;;) {
1418 struct timeval tv;
1419 struct dhcp_packet packet;
1420 /* silence "uninitialized!" warning */
1421 unsigned timestamp_before_wait = timestamp_before_wait;
1422
1423 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1424
1425 /* Was opening raw or udp socket here
1426 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1427 * but on fast network renew responses return faster
1428 * than we open sockets. Thus this code is moved
1429 * to change_listen_mode(). Thus we open listen socket
1430 * BEFORE we send renew request (see "case BOUND:"). */
1431
1432 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1433
1434 tv.tv_sec = timeout - already_waited_sec;
1435 tv.tv_usec = 0;
1436 retval = 0;
1437 /* If we already timed out, fall through with retval = 0, else... */
1438 if ((int)tv.tv_sec > 0) {
1439 log1("waiting on select %u seconds", (int)tv.tv_sec);
1440 timestamp_before_wait = (unsigned)monotonic_sec();
1441 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1442 if (retval < 0) {
1443 /* EINTR? A signal was caught, don't panic */
1444 if (errno == EINTR) {
1445 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1446 continue;
1447 }
1448 /* Else: an error occured, panic! */
1449 bb_perror_msg_and_die("select");
1450 }
1451 }
1452
1453 /* If timeout dropped to zero, time to become active:
1454 * resend discover/renew/whatever
1455 */
1456 if (retval == 0) {
1457 /* When running on a bridge, the ifindex may have changed
1458 * (e.g. if member interfaces were added/removed
1459 * or if the status of the bridge changed).
1460 * Refresh ifindex and client_mac:
1461 */
1462 if (udhcp_read_interface(client_config.interface,
1463 &client_config.ifindex,
1464 NULL,
1465 client_config.client_mac)
1466 ) {
1467 goto ret0; /* iface is gone? */
1468 }
1469 if (clientid_mac_ptr)
1470 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1471
1472 /* We will restart the wait in any case */
1473 already_waited_sec = 0;
1474
1475 switch (state) {
1476 case INIT_SELECTING:
1477 if (!discover_retries || packet_num < discover_retries) {
1478 if (packet_num == 0)
1479 xid = random_xid();
1480 /* broadcast */
1481 send_discover(xid, requested_ip);
1482 timeout = discover_timeout;
1483 packet_num++;
1484 continue;
1485 }
1486 leasefail:
1487 udhcp_run_script(NULL, "leasefail");
1488#if BB_MMU /* -b is not supported on NOMMU */
1489 if (opt & OPT_b) { /* background if no lease */
1490 bb_error_msg("no lease, forking to background");
1491 client_background();
1492 /* do not background again! */
1493 opt = ((opt & ~OPT_b) | OPT_f);
1494 } else
1495#endif
1496 if (opt & OPT_n) { /* abort if no lease */
1497 bb_error_msg("no lease, failing");
1498 retval = 1;
1499 goto ret;
1500 }
1501 /* wait before trying again */
1502 timeout = tryagain_timeout;
1503 packet_num = 0;
1504 continue;
1505 case REQUESTING:
1506 if (packet_num < 3) {
1507 /* send broadcast select packet */
1508 send_select(xid, server_addr, requested_ip);
1509 timeout = discover_timeout;
1510 packet_num++;
1511 continue;
1512 }
1513 /* Timed out, go back to init state.
1514 * "discover...select...discover..." loops
1515 * were seen in the wild. Treat them similarly
1516 * to "no response to discover" case */
1517 change_listen_mode(LISTEN_RAW);
1518 state = INIT_SELECTING;
1519 goto leasefail;
1520 case BOUND:
1521 /* 1/2 lease passed, enter renewing state */
1522 state = RENEWING;
1523 client_config.first_secs = 0; /* make secs field count from 0 */
1524 change_listen_mode(LISTEN_KERNEL);
1525 log1("entering renew state");
1526 /* fall right through */
1527 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1528 case_RENEW_REQUESTED:
1529 case RENEWING:
1530 if (timeout > 60) {
1531 /* send an unicast renew request */
1532 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1533 * a new UDP socket for sending inside send_renew.
1534 * I hazard to guess existing listening socket
1535 * is somehow conflicting with it, but why is it
1536 * not deterministic then?! Strange.
1537 * Anyway, it does recover by eventually failing through
1538 * into INIT_SELECTING state.
1539 */
1540 send_renew(xid, server_addr, requested_ip);
1541 timeout >>= 1;
1542 continue;
1543 }
1544 /* Timed out, enter rebinding state */
1545 log1("entering rebinding state");
1546 state = REBINDING;
1547 /* fall right through */
1548 case REBINDING:
1549 /* Switch to bcast receive */
1550 change_listen_mode(LISTEN_RAW);
1551 /* Lease is *really* about to run out,
1552 * try to find DHCP server using broadcast */
1553 if (timeout > 0) {
1554 /* send a broadcast renew request */
1555 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1556 timeout >>= 1;
1557 continue;
1558 }
1559 /* Timed out, enter init state */
1560 bb_error_msg("lease lost, entering init state");
1561 udhcp_run_script(NULL, "deconfig");
1562 state = INIT_SELECTING;
1563 client_config.first_secs = 0; /* make secs field count from 0 */
1564 /*timeout = 0; - already is */
1565 packet_num = 0;
1566 continue;
1567 /* case RELEASED: */
1568 }
1569 /* yah, I know, *you* say it would never happen */
1570 timeout = INT_MAX;
1571 continue; /* back to main loop */
1572 } /* if select timed out */
1573
1574 /* select() didn't timeout, something happened */
1575
1576 /* Is it a signal? */
1577 /* note: udhcp_sp_read checks FD_ISSET before reading */
1578 switch (udhcp_sp_read(&rfds)) {
1579 case SIGUSR1:
1580 client_config.first_secs = 0; /* make secs field count from 0 */
1581 already_waited_sec = 0;
1582 perform_renew();
1583 if (state == RENEW_REQUESTED) {
1584 /* We might be either on the same network
1585 * (in which case renew might work),
1586 * or we might be on a completely different one
1587 * (in which case renew won't ever succeed).
1588 * For the second case, must make sure timeout
1589 * is not too big, or else we can send
1590 * futile renew requests for hours.
1591 * (Ab)use -A TIMEOUT value (usually 20 sec)
1592 * as a cap on the timeout.
1593 */
1594 if (timeout > tryagain_timeout)
1595 timeout = tryagain_timeout;
1596 goto case_RENEW_REQUESTED;
1597 }
1598 /* Start things over */
1599 packet_num = 0;
1600 /* Kill any timeouts, user wants this to hurry along */
1601 timeout = 0;
1602 continue;
1603 case SIGUSR2:
1604 perform_release(server_addr, requested_ip);
1605 timeout = INT_MAX;
1606 continue;
1607 case SIGTERM:
1608 bb_error_msg("received %s", "SIGTERM");
1609 goto ret0;
1610 }
1611
1612 /* Is it a packet? */
1613 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1614 continue; /* no */
1615
1616 {
1617 int len;
1618
1619 /* A packet is ready, read it */
1620 if (listen_mode == LISTEN_KERNEL)
1621 len = udhcp_recv_kernel_packet(&packet, sockfd);
1622 else
1623 len = udhcp_recv_raw_packet(&packet, sockfd);
1624 if (len == -1) {
1625 /* Error is severe, reopen socket */
1626 bb_error_msg("read error: %s, reopening socket", strerror(errno));
1627 sleep(discover_timeout); /* 3 seconds by default */
1628 change_listen_mode(listen_mode); /* just close and reopen */
1629 }
1630 /* If this packet will turn out to be unrelated/bogus,
1631 * we will go back and wait for next one.
1632 * Be sure timeout is properly decreased. */
1633 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1634 if (len < 0)
1635 continue;
1636 }
1637
1638 if (packet.xid != xid) {
1639 log1("xid %x (our is %x), ignoring packet",
1640 (unsigned)packet.xid, (unsigned)xid);
1641 continue;
1642 }
1643
1644 /* Ignore packets that aren't for us */
1645 if (packet.hlen != 6
1646 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1647 ) {
1648//FIXME: need to also check that last 10 bytes are zero
1649 log1("chaddr does not match, ignoring packet"); // log2?
1650 continue;
1651 }
1652
1653 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1654 if (message == NULL) {
1655 bb_error_msg("no message type option, ignoring packet");
1656 continue;
1657 }
1658
1659 switch (state) {
1660 case INIT_SELECTING:
1661 /* Must be a DHCPOFFER */
1662 if (*message == DHCPOFFER) {
1663 uint8_t *temp;
1664
1665/* What exactly is server's IP? There are several values.
1666 * Example DHCP offer captured with tchdump:
1667 *
1668 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1669 * BOOTP fields:
1670 * Your-IP 10.34.25.202
1671 * Server-IP 10.34.32.125 // "next server" IP
1672 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1673 * DHCP options:
1674 * DHCP-Message Option 53, length 1: Offer
1675 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1676 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1677 *
1678 * We think that real server IP (one to use in renew/release)
1679 * is one in Server-ID option. But I am not 100% sure.
1680 * IP header's src and Gateway-IP (same in this example)
1681 * might work too.
1682 * "Next server" and router are definitely wrong ones to use, though...
1683 */
1684/* We used to ignore pcakets without DHCP_SERVER_ID.
1685 * I've got user reports from people who run "address-less" servers.
1686 * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1687 * They say ISC DHCP client supports this case.
1688 */
1689 server_addr = 0;
1690 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1691 if (!temp) {
1692 bb_error_msg("no server ID, using 0.0.0.0");
1693 } else {
1694 /* it IS unaligned sometimes, don't "optimize" */
1695 move_from_unaligned32(server_addr, temp);
1696 }
1697 /*xid = packet.xid; - already is */
1698 requested_ip = packet.yiaddr;
1699
1700 /* enter requesting state */
1701 state = REQUESTING;
1702 timeout = 0;
1703 packet_num = 0;
1704 already_waited_sec = 0;
1705 }
1706 continue;
1707 case REQUESTING:
1708 case RENEWING:
1709 case RENEW_REQUESTED:
1710 case REBINDING:
1711 if (*message == DHCPACK) {
1712 unsigned start;
1713 uint32_t lease_seconds;
1714 struct in_addr temp_addr;
1715 uint8_t *temp;
1716
1717 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1718 if (!temp) {
1719 bb_error_msg("no lease time with ACK, using 1 hour lease");
1720 lease_seconds = 60 * 60;
1721 } else {
1722 /* it IS unaligned sometimes, don't "optimize" */
1723 move_from_unaligned32(lease_seconds, temp);
1724 lease_seconds = ntohl(lease_seconds);
1725 /* paranoia: must not be too small and not prone to overflows */
1726 if (lease_seconds < 0x10)
1727 lease_seconds = 0x10;
1728 if (lease_seconds >= 0x10000000)
1729 lease_seconds = 0x0fffffff;
1730 }
1731#if ENABLE_FEATURE_UDHCPC_ARPING
1732 if (opt & OPT_a) {
1733/* RFC 2131 3.1 paragraph 5:
1734 * "The client receives the DHCPACK message with configuration
1735 * parameters. The client SHOULD perform a final check on the
1736 * parameters (e.g., ARP for allocated network address), and notes
1737 * the duration of the lease specified in the DHCPACK message. At this
1738 * point, the client is configured. If the client detects that the
1739 * address is already in use (e.g., through the use of ARP),
1740 * the client MUST send a DHCPDECLINE message to the server and restarts
1741 * the configuration process..." */
1742 if (!arpping(packet.yiaddr,
1743 NULL,
1744 (uint32_t) 0,
1745 client_config.client_mac,
1746 client_config.interface,
1747 arpping_ms)
1748 ) {
1749 bb_error_msg("offered address is in use "
1750 "(got ARP reply), declining");
1751 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1752
1753 if (state != REQUESTING)
1754 udhcp_run_script(NULL, "deconfig");
1755 change_listen_mode(LISTEN_RAW);
1756 state = INIT_SELECTING;
1757 client_config.first_secs = 0; /* make secs field count from 0 */
1758 requested_ip = 0;
1759 timeout = tryagain_timeout;
1760 packet_num = 0;
1761 already_waited_sec = 0;
1762 continue; /* back to main loop */
1763 }
1764 }
1765#endif
1766 /* enter bound state */
1767 temp_addr.s_addr = packet.yiaddr;
1768 bb_error_msg("lease of %s obtained, lease time %u",
1769 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1770 requested_ip = packet.yiaddr;
1771
1772 start = monotonic_sec();
1773 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1774 already_waited_sec = (unsigned)monotonic_sec() - start;
1775 timeout = lease_seconds / 2;
1776 if ((unsigned)timeout < already_waited_sec) {
1777 /* Something went wrong. Back to discover state */
1778 timeout = already_waited_sec = 0;
1779 }
1780
1781 state = BOUND;
1782 change_listen_mode(LISTEN_NONE);
1783 if (opt & OPT_q) { /* quit after lease */
1784 goto ret0;
1785 }
1786 /* future renew failures should not exit (JM) */
1787 opt &= ~OPT_n;
1788#if BB_MMU /* NOMMU case backgrounded earlier */
1789 if (!(opt & OPT_f)) {
1790 client_background();
1791 /* do not background again! */
1792 opt = ((opt & ~OPT_b) | OPT_f);
1793 }
1794#endif
1795 /* make future renew packets use different xid */
1796 /* xid = random_xid(); ...but why bother? */
1797
1798 continue; /* back to main loop */
1799 }
1800 if (*message == DHCPNAK) {
1801 /* If network has more than one DHCP server,
1802 * "wrong" server can reply first, with a NAK.
1803 * Do not interpret it as a NAK from "our" server.
1804 */
1805 if (server_addr != 0) {
1806 uint32_t svid;
1807 uint8_t *temp;
1808
1809 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1810 if (!temp) {
1811 non_matching_svid:
1812 log1("%s with wrong server ID, ignoring packet",
1813 "Received DHCP NAK"
1814 );
1815 continue;
1816 }
1817 move_from_unaligned32(svid, temp);
1818 if (svid != server_addr)
1819 goto non_matching_svid;
1820 }
1821 /* return to init state */
1822 bb_error_msg("received %s", "DHCP NAK");
1823 udhcp_run_script(&packet, "nak");
1824 if (state != REQUESTING)
1825 udhcp_run_script(NULL, "deconfig");
1826 change_listen_mode(LISTEN_RAW);
1827 sleep(3); /* avoid excessive network traffic */
1828 state = INIT_SELECTING;
1829 client_config.first_secs = 0; /* make secs field count from 0 */
1830 requested_ip = 0;
1831 timeout = 0;
1832 packet_num = 0;
1833 already_waited_sec = 0;
1834 }
1835 continue;
1836 /* case BOUND: - ignore all packets */
1837 /* case RELEASED: - ignore all packets */
1838 }
1839 /* back to main loop */
1840 } /* for (;;) - main loop ends */
1841
1842 ret0:
1843 if (opt & OPT_R) /* release on quit */
1844 perform_release(server_addr, requested_ip);
1845 retval = 0;
1846 ret:
1847 /*if (client_config.pidfile) - remove_pidfile has its own check */
1848 remove_pidfile(client_config.pidfile);
1849 return retval;
1850}
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