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[tomato.git] / release / src / router / busybox / networking / udhcp / dhcpc.c
blobd7b7862e78afba9072f243795a199c38a0ddccab
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 #if ENABLE_LONG_OPTS
42 static const char udhcpc_longopts[] ALIGN1 =
43 "clientid-none\0" No_argument "C"
44 "vendorclass\0" Required_argument "V"
45 "hostname\0" Required_argument "H"
46 "fqdn\0" Required_argument "F"
47 "interface\0" Required_argument "i"
48 "now\0" No_argument "n"
49 "pidfile\0" Required_argument "p"
50 "quit\0" No_argument "q"
51 "release\0" No_argument "R"
52 "request\0" Required_argument "r"
53 "script\0" Required_argument "s"
54 "timeout\0" Required_argument "T"
55 "version\0" No_argument "v"
56 "retries\0" Required_argument "t"
57 "tryagain\0" Required_argument "A"
58 "syslog\0" No_argument "S"
59 "request-option\0" Required_argument "O"
60 "no-default-options\0" No_argument "o"
61 "foreground\0" No_argument "f"
62 "background\0" No_argument "b"
63 "broadcast\0" No_argument "B"
64 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
65 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
66 ;
67 #endif
68 /* Must match getopt32 option string order */
69 enum {
70 OPT_C = 1 << 0,
71 OPT_V = 1 << 1,
72 OPT_H = 1 << 2,
73 OPT_h = 1 << 3,
74 OPT_F = 1 << 4,
75 OPT_i = 1 << 5,
76 OPT_n = 1 << 6,
77 OPT_p = 1 << 7,
78 OPT_q = 1 << 8,
79 OPT_R = 1 << 9,
80 OPT_r = 1 << 10,
81 OPT_s = 1 << 11,
82 OPT_T = 1 << 12,
83 OPT_t = 1 << 13,
84 OPT_S = 1 << 14,
85 OPT_A = 1 << 15,
86 OPT_O = 1 << 16,
87 OPT_o = 1 << 17,
88 OPT_x = 1 << 18,
89 OPT_f = 1 << 19,
90 OPT_B = 1 << 20,
91 OPT_m = 1 << 21, // zzz
92 /* The rest has variable bit positions, need to be clever */
93 OPTBIT_LAST = 21,
94 USE_FOR_MMU( OPTBIT_b,)
95 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
96 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
97 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
98 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
99 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
100 };
101
102
103 /*** Script execution code ***/
104
105 /* get a rough idea of how long an option will be (rounding up...) */
106 static const uint8_t len_of_option_as_string[] = {
107 [OPTION_IP ] = sizeof("255.255.255.255 "),
108 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
109 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
110 #if ENABLE_FEATURE_UDHCP_RFC5969
111 [OPTION_6RD ] = sizeof("32 128 FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF 255.255.255.255 "),
112 #endif
113 [OPTION_STRING ] = 1,
114 #if ENABLE_FEATURE_UDHCP_RFC3397
115 [OPTION_DNS_STRING ] = 1, /* unused */
116 /* Hmmm, this severely overestimates size if SIP_SERVERS option
117 * is in domain name form: N-byte option in binary form
118 * mallocs ~16*N bytes. But it is freed almost at once.
119 */
120 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
121 #endif
122 // [OPTION_BOOLEAN ] = sizeof("yes "),
123 [OPTION_U8 ] = sizeof("255 "),
124 [OPTION_U16 ] = sizeof("65535 "),
125 // [OPTION_S16 ] = sizeof("-32768 "),
126 [OPTION_U32 ] = sizeof("4294967295 "),
127 [OPTION_S32 ] = sizeof("-2147483684 "),
128 };
129
130 /* note: ip is a pointer to an IP in network order, possibly misaliged */
131 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
132 {
133 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
134 }
135
136 /* really simple implementation, just count the bits */
137 static int mton(uint32_t mask)
138 {
139 int i = 0;
140 mask = ntohl(mask); /* 111110000-like bit pattern */
141 while (mask) {
142 i++;
143 mask <<= 1;
144 }
145 return i;
146 }
147
148 /* Create "opt_name=opt_value" string */
149 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
150 {
151 unsigned upper_length;
152 int len, type, optlen;
153 char *dest, *ret;
154
155 /* option points to OPT_DATA, need to go back and get OPT_LEN */
156 len = option[OPT_LEN - OPT_DATA];
157
158 type = optflag->flags & OPTION_TYPE_MASK;
159 optlen = dhcp_option_lengths[type];
160 upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen);
161
162 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
163 dest += sprintf(ret, "%s=", opt_name);
164
165 while (len >= optlen) {
166 unsigned ip_ofs = 0;
167
168 switch (type) {
169 case OPTION_IP_PAIR:
170 dest += sprint_nip(dest, "", option);
171 *dest++ = '/';
172 ip_ofs = 4;
173 /* fall through */
174 case OPTION_IP:
175 dest += sprint_nip(dest, "", option + ip_ofs);
176 break;
177 // case OPTION_BOOLEAN:
178 // dest += sprintf(dest, *option ? "yes" : "no");
179 // break;
180 case OPTION_U8:
181 dest += sprintf(dest, "%u", *option);
182 break;
183 // case OPTION_S16:
184 case OPTION_U16: {
185 uint16_t val_u16;
186 move_from_unaligned16(val_u16, option);
187 dest += sprintf(dest, "%u", ntohs(val_u16));
188 break;
189 }
190 case OPTION_S32:
191 case OPTION_U32: {
192 uint32_t val_u32;
193 move_from_unaligned32(val_u32, option);
194 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
195 break;
196 }
197 case OPTION_STRING:
198 memcpy(dest, option, len);
199 dest[len] = '\0';
200 return ret; /* Short circuit this case */
201 case OPTION_STATIC_ROUTES: {
202 /* Option binary format:
203 * mask [one byte, 0..32]
204 * ip [big endian, 0..4 bytes depending on mask]
205 * router [big endian, 4 bytes]
206 * may be repeated
207 *
208 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
209 */
210 const char *pfx = "";
211
212 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
213 uint32_t nip;
214 uint8_t *p;
215 unsigned mask;
216 int bytes;
217
218 mask = *option++;
219 if (mask > 32)
220 break;
221 len--;
222
223 nip = 0;
224 p = (void*) &nip;
225 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
226 while (--bytes >= 0) {
227 *p++ = *option++;
228 len--;
229 }
230 if (len < 4)
231 break;
232
233 /* print ip/mask */
234 dest += sprint_nip(dest, pfx, (void*) &nip);
235 pfx = " ";
236 dest += sprintf(dest, "/%u ", mask);
237 /* print router */
238 dest += sprint_nip(dest, "", option);
239 option += 4;
240 len -= 4;
241 }
242
243 return ret;
244 }
245 #if ENABLE_FEATURE_UDHCP_RFC3397
246 case OPTION_DNS_STRING:
247 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
248 dest = dname_dec(option, len, ret);
249 if (dest) {
250 free(ret);
251 return dest;
252 }
253 /* error. return "optname=" string */
254 return ret;
255 case OPTION_SIP_SERVERS:
256 /* Option binary format:
257 * type: byte
258 * type=0: domain names, dns-compressed
259 * type=1: IP addrs
260 */
261 option++;
262 len--;
263 if (option[-1] == 0) {
264 dest = dname_dec(option, len, ret);
265 if (dest) {
266 free(ret);
267 return dest;
268 }
269 } else
270 if (option[-1] == 1) {
271 const char *pfx = "";
272 while (1) {
273 len -= 4;
274 if (len < 0)
275 break;
276 dest += sprint_nip(dest, pfx, option);
277 pfx = " ";
278 option += 4;
279 }
280 }
281 return ret;
282 #endif
283 #if ENABLE_FEATURE_UDHCP_RFC5969
284 case OPTION_6RD:
285 /* Option binary format:
286 * 0 1 2 3
287 * 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
288 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
289 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
290 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
291 * | |
292 * | 6rdPrefix |
293 * | (16 octets) |
294 * | |
295 * | |
296 * | |
297 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
298 * | 6rdBRIPv4Address(es) |
299 * . .
300 * . .
301 * . .
302 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
303 *
304 * We convert it to a string "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address"
305 */
306
307 /* Sanity check: ensure that our length is at least 22 bytes, that
308 * IPv4MaskLen is <= 32, 6rdPrefixLen <= 128 and that the sum of
309 * (32 - IPv4MaskLen) + 6rdPrefixLen is less than or equal to 128.
310 * If any of these requirements is not fulfilled, return with empty
311 * value.
312 */
313 if ((len >= 22) && (*option <= 32) && (*(option+1) <= 128) &&
314 (((32 - *option) + *(option+1)) <= 128))
315 {
316 /* IPv4MaskLen */
317 dest += sprintf(dest, "%u ", *option++);
318 len--;
319
320 /* 6rdPrefixLen */
321 dest += sprintf(dest, "%u ", *option++);
322 len--;
323
324 /* 6rdPrefix */
325 dest += sprint_nip6(dest, /* "", */ option);
326 option += 16;
327 len -= 16;
328
329 /* 6rdBRIPv4Addresses */
330 while (len >= 4)
331 {
332 dest += sprint_nip(dest, " ", option);
333 option += 4;
334 len -= 4;
335
336 /* the code to determine the option size fails to work with
337 * lengths that are not a multiple of the minimum length,
338 * adding all advertised 6rdBRIPv4Addresses here would
339 * overflow the destination buffer, therefore skip the rest
340 * for now
341 */
342 break;
343 }
344 }
345
346 return ret;
347 #endif
348 } /* switch */
349 option += optlen;
350 len -= optlen;
351 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
352 // Should we bail out/warn if we see multi-ip option which is
353 // not allowed to be such (for example, DHCP_BROADCAST)? -
354 if (len <= 0 /* || !(optflag->flags & OPTION_LIST) */)
355 break;
356 *dest++ = ' ';
357 *dest = '\0';
358 }
359 return ret;
360 }
361
362 /* put all the parameters into the environment */
363 static char **fill_envp(struct dhcp_packet *packet)
364 {
365 int envc;
366 int i;
367 char **envp, **curr;
368 const char *opt_name;
369 uint8_t *temp;
370 uint8_t overload = 0;
371
372 /* We need 6 elements for:
373 * "interface=IFACE"
374 * "ip=N.N.N.N" from packet->yiaddr
375 * "siaddr=IP" from packet->siaddr_nip (unless 0)
376 * "boot_file=FILE" from packet->file (unless overloaded)
377 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
378 * terminating NULL
379 */
380 envc = 6;
381 /* +1 element for each option, +2 for subnet option: */
382 if (packet) {
383 for (i = 0; dhcp_optflags[i].code; i++) {
384 if (udhcp_get_option(packet, dhcp_optflags[i].code)) {
385 if (dhcp_optflags[i].code == DHCP_SUBNET)
386 envc++; /* for mton */
387 envc++;
388 }
389 }
390 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
391 if (temp)
392 overload = *temp;
393 }
394 curr = envp = xzalloc(sizeof(char *) * envc);
395
396 *curr = xasprintf("interface=%s", client_config.interface);
397 putenv(*curr++);
398
399 if (!packet)
400 return envp;
401
402 *curr = xmalloc(sizeof("ip=255.255.255.255"));
403 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
404 putenv(*curr++);
405
406 opt_name = dhcp_option_strings;
407 i = 0;
408 while (*opt_name) {
409 temp = udhcp_get_option(packet, dhcp_optflags[i].code);
410 if (!temp)
411 goto next;
412 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
413 putenv(*curr++);
414 if (dhcp_optflags[i].code == DHCP_SUBNET) {
415 /* Subnet option: make things like "$ip/$mask" possible */
416 uint32_t subnet;
417 move_from_unaligned32(subnet, temp);
418 *curr = xasprintf("mask=%d", mton(subnet));
419 putenv(*curr++);
420 }
421 next:
422 opt_name += strlen(opt_name) + 1;
423 i++;
424 }
425 if (packet->siaddr_nip) {
426 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
427 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
428 putenv(*curr++);
429 }
430 if (!(overload & FILE_FIELD) && packet->file[0]) {
431 /* watch out for invalid packets */
432 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
433 putenv(*curr++);
434 }
435 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
436 /* watch out for invalid packets */
437 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
438 putenv(*curr++);
439 }
440 return envp;
441 }
442
443 /* Call a script with a par file and env vars */
444 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
445 {
446 char **envp, **curr;
447 char *argv[3];
448
449 if (client_config.script == NULL)
450 return;
451
452 envp = fill_envp(packet);
453
454 /* call script */
455 log1("Executing %s %s", client_config.script, name);
456 argv[0] = (char*) client_config.script;
457 argv[1] = (char*) name;
458 argv[2] = NULL;
459 spawn_and_wait(argv);
460
461 for (curr = envp; *curr; curr++) {
462 log2(" %s", *curr);
463 bb_unsetenv_and_free(*curr);
464 }
465 free(envp);
466 }
467
468
469 /*** Sending/receiving packets ***/
470
471 static ALWAYS_INLINE uint32_t random_xid(void)
472 {
473 return rand();
474 }
475
476 /* Initialize the packet with the proper defaults */
477 static void init_packet(struct dhcp_packet *packet, char type)
478 {
479 uint16_t secs;
480
481 /* Fill in: op, htype, hlen, cookie fields; message type option: */
482 udhcp_init_header(packet, type);
483
484 packet->xid = random_xid();
485
486 client_config.last_secs = monotonic_sec();
487 if (client_config.first_secs == 0)
488 client_config.first_secs = client_config.last_secs;
489 secs = client_config.last_secs - client_config.first_secs;
490 packet->secs = htons(secs);
491
492 memcpy(packet->chaddr, client_config.client_mac, 6);
493 if (client_config.clientid)
494 udhcp_add_binary_option(packet, client_config.clientid);
495 }
496
497 static void add_client_options(struct dhcp_packet *packet)
498 {
499 uint8_t c;
500 int i, end, len;
501
502 len = sizeof(struct ip_udp_dhcp_packet);
503 if (client_config.client_mtu == 0 ||
504 client_config.client_mtu > len)
505 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(len));
506
507 /* Add a "param req" option with the list of options we'd like to have
508 * from stubborn DHCP servers. Pull the data from the struct in common.c.
509 * No bounds checking because it goes towards the head of the packet. */
510 end = udhcp_end_option(packet->options);
511 len = 0;
512 for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
513 if (( (dhcp_optflags[i].flags & OPTION_REQ)
514 && !client_config.no_default_options
515 )
516 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
517 ) {
518 packet->options[end + OPT_DATA + len] = c;
519 len++;
520 }
521 }
522 if (len) {
523 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
524 packet->options[end + OPT_LEN] = len;
525 packet->options[end + OPT_DATA + len] = DHCP_END;
526 }
527
528 if (client_config.vendorclass)
529 udhcp_add_binary_option(packet, client_config.vendorclass);
530 if (client_config.hostname)
531 udhcp_add_binary_option(packet, client_config.hostname);
532 if (client_config.fqdn)
533 udhcp_add_binary_option(packet, client_config.fqdn);
534
535 /* Request broadcast replies if we have no IP addr */
536 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
537 packet->flags |= htons(BROADCAST_FLAG);
538
539 /* Add -x options if any */
540 {
541 struct option_set *curr = client_config.options;
542 while (curr) {
543 udhcp_add_binary_option(packet, curr->data);
544 curr = curr->next;
545 }
546 // if (client_config.sname)
547 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
548 // if (client_config.boot_file)
549 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
550 }
551 }
552
553 /* RFC 2131
554 * 4.4.4 Use of broadcast and unicast
555 *
556 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
557 * messages, unless the client knows the address of a DHCP server.
558 * The client unicasts DHCPRELEASE messages to the server. Because
559 * the client is declining the use of the IP address supplied by the server,
560 * the client broadcasts DHCPDECLINE messages.
561 *
562 * When the DHCP client knows the address of a DHCP server, in either
563 * INIT or REBOOTING state, the client may use that address
564 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
565 * The client may also use unicast to send DHCPINFORM messages
566 * to a known DHCP server. If the client receives no response to DHCP
567 * messages sent to the IP address of a known DHCP server, the DHCP
568 * client reverts to using the IP broadcast address.
569 */
570
571 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
572 {
573 return udhcp_send_raw_packet(packet,
574 /*src*/ INADDR_ANY, CLIENT_PORT,
575 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
576 client_config.ifindex);
577 }
578
579 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
580 /* NOINLINE: limit stack usage in caller */
581 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
582 {
583 struct dhcp_packet packet;
584 static int msgs = 0;
585
586 /* Fill in: op, htype, hlen, cookie, chaddr fields,
587 * random xid field (we override it below),
588 * client-id option (unless -C), message type option:
589 */
590 init_packet(&packet, DHCPDISCOVER);
591
592 packet.xid = xid;
593 if (requested)
594 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
595
596 /* Add options: maxsize,
597 * optionally: hostname, fqdn, vendorclass,
598 * "param req" option according to -O, options specified with -x
599 */
600 add_client_options(&packet);
601
602 if (msgs++ < 3)
603 bb_info_msg("Sending discover...");
604 return raw_bcast_from_client_config_ifindex(&packet);
605 }
606
607 /* Broadcast a DHCP request message */
608 /* RFC 2131 3.1 paragraph 3:
609 * "The client _broadcasts_ a DHCPREQUEST message..."
610 */
611 /* NOINLINE: limit stack usage in caller */
612 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
613 {
614 struct dhcp_packet packet;
615 struct in_addr addr;
616
617 /*
618 * RFC 2131 4.3.2 DHCPREQUEST message
619 * ...
620 * If the DHCPREQUEST message contains a 'server identifier'
621 * option, the message is in response to a DHCPOFFER message.
622 * Otherwise, the message is a request to verify or extend an
623 * existing lease. If the client uses a 'client identifier'
624 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
625 * in all subsequent messages. If the client included a list
626 * of requested parameters in a DHCPDISCOVER message, it MUST
627 * include that list in all subsequent messages.
628 */
629 /* Fill in: op, htype, hlen, cookie, chaddr fields,
630 * random xid field (we override it below),
631 * client-id option (unless -C), message type option:
632 */
633 init_packet(&packet, DHCPREQUEST);
634
635 packet.xid = xid;
636 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
637
638 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
639
640 /* Add options: maxsize,
641 * optionally: hostname, fqdn, vendorclass,
642 * "param req" option according to -O, and options specified with -x
643 */
644 add_client_options(&packet);
645
646 addr.s_addr = requested;
647 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
648 return raw_bcast_from_client_config_ifindex(&packet);
649 }
650
651 /* Unicast or broadcast a DHCP renew message */
652 /* NOINLINE: limit stack usage in caller */
653 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
654 {
655 struct dhcp_packet packet;
656
657 /*
658 * RFC 2131 4.3.2 DHCPREQUEST message
659 * ...
660 * DHCPREQUEST generated during RENEWING state:
661 *
662 * 'server identifier' MUST NOT be filled in, 'requested IP address'
663 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
664 * client's IP address. In this situation, the client is completely
665 * configured, and is trying to extend its lease. This message will
666 * be unicast, so no relay agents will be involved in its
667 * transmission. Because 'giaddr' is therefore not filled in, the
668 * DHCP server will trust the value in 'ciaddr', and use it when
669 * replying to the client.
670 */
671 /* Fill in: op, htype, hlen, cookie, chaddr fields,
672 * random xid field (we override it below),
673 * client-id option (unless -C), message type option:
674 */
675 init_packet(&packet, DHCPREQUEST);
676
677 packet.xid = xid;
678 packet.ciaddr = ciaddr;
679
680 /* Add options: maxsize,
681 * optionally: hostname, fqdn, vendorclass,
682 * "param req" option according to -O, and options specified with -x
683 */
684 add_client_options(&packet);
685
686 bb_info_msg("Sending renew...");
687 if (server)
688 return udhcp_send_kernel_packet(&packet,
689 ciaddr, CLIENT_PORT,
690 server, SERVER_PORT);
691 return raw_bcast_from_client_config_ifindex(&packet);
692 }
693
694 #if ENABLE_FEATURE_UDHCPC_ARPING
695 /* Broadcast a DHCP decline message */
696 /* NOINLINE: limit stack usage in caller */
697 static NOINLINE int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
698 {
699 struct dhcp_packet packet;
700
701 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
702 * client-id option (unless -C), message type option:
703 */
704 init_packet(&packet, DHCPDECLINE);
705
706 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
707 * but in case the server is buggy and wants DHCPDECLINE's xid
708 * to match the xid which started entire handshake,
709 * we use the same xid we used in initial DHCPDISCOVER:
710 */
711 packet.xid = xid;
712 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
713 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
714
715 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
716
717 bb_info_msg("Sending decline...");
718 return raw_bcast_from_client_config_ifindex(&packet);
719 }
720 #endif
721
722 /* Unicast a DHCP release message */
723 static int send_release(uint32_t server, uint32_t ciaddr)
724 {
725 struct dhcp_packet packet;
726
727 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
728 * client-id option (unless -C), message type option:
729 */
730 init_packet(&packet, DHCPRELEASE);
731
732 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
733 packet.ciaddr = ciaddr;
734
735 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
736
737 bb_info_msg("Sending release...");
738 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
739 }
740
741 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
742 /* NOINLINE: limit stack usage in caller */
743 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
744 {
745 int bytes;
746 struct ip_udp_dhcp_packet packet;
747 uint16_t check;
748
749 memset(&packet, 0, sizeof(packet));
750 bytes = safe_read(fd, &packet, sizeof(packet));
751 if (bytes < 0) {
752 log1("Packet read error, ignoring");
753 /* NB: possible down interface, etc. Caller should pause. */
754 return bytes; /* returns -1 */
755 }
756
757 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
758 log1("Packet is too short, ignoring");
759 return -2;
760 }
761
762 if (bytes < ntohs(packet.ip.tot_len)) {
763 /* packet is bigger than sizeof(packet), we did partial read */
764 log1("Oversized packet, ignoring");
765 return -2;
766 }
767
768 /* ignore any extra garbage bytes */
769 bytes = ntohs(packet.ip.tot_len);
770
771 /* make sure its the right packet for us, and that it passes sanity checks */
772 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
773 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
774 || packet.udp.dest != htons(CLIENT_PORT)
775 /* || bytes > (int) sizeof(packet) - can't happen */
776 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
777 ) {
778 log1("Unrelated/bogus packet, ignoring");
779 return -2;
780 }
781
782 /* verify IP checksum */
783 check = packet.ip.check;
784 packet.ip.check = 0;
785 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
786 log1("Bad IP header checksum, ignoring");
787 return -2;
788 }
789
790 /* verify UDP checksum. IP header has to be modified for this */
791 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
792 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
793 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
794 check = packet.udp.check;
795 packet.udp.check = 0;
796 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
797 log1("Packet with bad UDP checksum received, ignoring");
798 return -2;
799 }
800
801 memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
802
803 if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
804 bb_info_msg("Packet with bad magic, ignoring");
805 return -2;
806 }
807 log1("Got valid DHCP packet");
808 udhcp_dump_packet(dhcp_pkt);
809 return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
810 }
811
812
813 /*** Main ***/
814
815 static int sockfd = -1;
816
817 #define LISTEN_NONE 0
818 #define LISTEN_KERNEL 1
819 #define LISTEN_RAW 2
820 static smallint listen_mode;
821
822 /* initial state: (re)start DHCP negotiation */
823 #define INIT_SELECTING 0
824 /* discover was sent, DHCPOFFER reply received */
825 #define REQUESTING 1
826 /* select/renew was sent, DHCPACK reply received */
827 #define BOUND 2
828 /* half of lease passed, want to renew it by sending unicast renew requests */
829 #define RENEWING 3
830 /* renew requests were not answered, lease is almost over, send broadcast renew */
831 #define REBINDING 4
832 /* manually requested renew (SIGUSR1) */
833 #define RENEW_REQUESTED 5
834 /* release, possibly manually requested (SIGUSR2) */
835 #define RELEASED 6
836 static smallint state;
837
838 static int udhcp_raw_socket(int ifindex)
839 {
840 int fd;
841 struct sockaddr_ll sock;
842
843 /*
844 * Comment:
845 *
846 * I've selected not to see LL header, so BPF doesn't see it, too.
847 * The filter may also pass non-IP and non-ARP packets, but we do
848 * a more complete check when receiving the message in userspace.
849 *
850 * and filter shamelessly stolen from:
851 *
852 * http://www.flamewarmaster.de/software/dhcpclient/
853 *
854 * There are a few other interesting ideas on that page (look under
855 * "Motivation"). Use of netlink events is most interesting. Think
856 * of various network servers listening for events and reconfiguring.
857 * That would obsolete sending HUP signals and/or make use of restarts.
858 *
859 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
860 * License: GPL v2.
861 *
862 * TODO: make conditional?
863 */
864 static const struct sock_filter filter_instr[] = {
865 /* load 9th byte (protocol) */
866 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
867 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
868 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
869 /* L1: load halfword from offset 6 (flags and frag offset) */
870 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
871 /* jump to L4 if any bits in frag offset field are set, else to L2 */
872 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
873 /* L2: skip IP header (load index reg with header len) */
874 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
875 /* load udp destination port from halfword[header_len + 2] */
876 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
877 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
878 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
879 /* L3: accept packet */
880 BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
881 /* L4: discard packet */
882 BPF_STMT(BPF_RET|BPF_K, 0),
883 };
884 static const struct sock_fprog filter_prog = {
885 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
886 /* casting const away: */
887 .filter = (struct sock_filter *) filter_instr,
888 };
889
890 log1("Opening raw socket on ifindex %d", ifindex); //log2?
891
892 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
893 log1("Got raw socket fd %d", fd); //log2?
894
895 sock.sll_family = AF_PACKET;
896 sock.sll_protocol = htons(ETH_P_IP);
897 sock.sll_ifindex = ifindex;
898 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
899
900 if (CLIENT_PORT == 68) {
901 /* Use only if standard port is in use */
902 /* Ignoring error (kernel may lack support for this) */
903 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
904 sizeof(filter_prog)) >= 0)
905 log1("Attached filter to raw socket fd %d", fd); // log?
906 }
907
908 log1("Created raw socket");
909
910 return fd;
911 }
912
913 static void change_listen_mode(int new_mode)
914 {
915 log1("Entering listen mode: %s",
916 new_mode != LISTEN_NONE
917 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
918 : "none"
919 );
920
921 listen_mode = new_mode;
922 if (sockfd >= 0) {
923 close(sockfd);
924 sockfd = -1;
925 }
926 if (new_mode == LISTEN_KERNEL)
927 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
928 else if (new_mode != LISTEN_NONE)
929 sockfd = udhcp_raw_socket(client_config.ifindex);
930 /* else LISTEN_NONE: sockfd stays closed */
931 }
932
933 /* Called only on SIGUSR1 */
934 static void perform_renew(void)
935 {
936 bb_info_msg("Performing a DHCP renew");
937 switch (state) {
938 case BOUND:
939 change_listen_mode(LISTEN_RAW); // zzz
940 case RENEWING:
941 case REBINDING:
942 // state = RENEW_REQUESTED; // zzz
943 // break;
944 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
945 case REQUESTING:
946 case RELEASED:
947 change_listen_mode(LISTEN_RAW);
948 state = INIT_SELECTING;
949 break;
950 case INIT_SELECTING:
951 break;
952 }
953 }
954
955 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
956 {
957 char buffer[sizeof("255.255.255.255")];
958 struct in_addr temp_addr;
959
960 /* send release packet */
961 if (state == BOUND || state == RENEWING || state == REBINDING) {
962 temp_addr.s_addr = server_addr;
963 strcpy(buffer, inet_ntoa(temp_addr));
964 temp_addr.s_addr = requested_ip;
965 bb_info_msg("Unicasting a release of %s to %s",
966 inet_ntoa(temp_addr), buffer);
967 send_release(server_addr, requested_ip); /* unicast */
968 udhcp_run_script(NULL, "deconfig");
969 }
970 bb_info_msg("Entering released state");
971
972 change_listen_mode(LISTEN_NONE);
973 state = RELEASED;
974 }
975
976 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
977 {
978 uint8_t *storage;
979 int len = strnlen(str, 255);
980 storage = xzalloc(len + extra + OPT_DATA);
981 storage[OPT_CODE] = code;
982 storage[OPT_LEN] = len + extra;
983 memcpy(storage + extra + OPT_DATA, str, len);
984 return storage;
985 }
986
987 #if BB_MMU
988 static void client_background(void)
989 {
990 bb_daemonize(0);
991 logmode &= ~LOGMODE_STDIO;
992 /* rewrite pidfile, as our pid is different now */
993 write_pidfile(client_config.pidfile);
994 }
995 #endif
996
997 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
998 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
999 //usage:#else
1000 //usage:# define IF_UDHCP_VERBOSE(...)
1001 //usage:#endif
1002 //usage:#define udhcpc_trivial_usage
1003 //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
1004 //usage: " [-H HOSTNAME] [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
1005 //usage:#define udhcpc_full_usage "\n"
1006 //usage: IF_LONG_OPTS(
1007 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1008 //usage: "\n -p,--pidfile FILE Create pidfile"
1009 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1010 //usage: "\n -B,--broadcast Request broadcast replies"
1011 //usage: "\n -t,--retries N Send up to N discover packets"
1012 //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
1013 //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
1014 //usage: "\n -f,--foreground Run in foreground"
1015 //usage: USE_FOR_MMU(
1016 //usage: "\n -b,--background Background if lease is not obtained"
1017 //usage: )
1018 //usage: "\n -n,--now Exit if lease is not obtained"
1019 //usage: "\n -q,--quit Exit after obtaining lease"
1020 //usage: "\n -R,--release Release IP on exit"
1021 //usage: "\n -S,--syslog Log to syslog too"
1022 //usage: IF_FEATURE_UDHCP_PORT(
1023 //usage: "\n -P,--client-port N Use port N (default 68)"
1024 //usage: )
1025 //usage: IF_FEATURE_UDHCPC_ARPING(
1026 //usage: "\n -a,--arping Use arping to validate offered address"
1027 //usage: )
1028 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1029 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1030 //usage: "\n -r,--request IP Request this IP address"
1031 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1032 //usage: "\n Examples of string, numeric, and hex byte opts:"
1033 //usage: "\n -x hostname:bbox - option 12"
1034 //usage: "\n -x lease:3600 - option 51 (lease time)"
1035 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1036 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1037 //usage: "\n -H,-h,--hostname NAME Send NAME as client hostname (default none)"
1038 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1039 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1040 //usage: IF_UDHCP_VERBOSE(
1041 //usage: "\n -v Verbose"
1042 //usage: )
1043 //usage: )
1044 //usage: IF_NOT_LONG_OPTS(
1045 //usage: "\n -i IFACE Interface to use (default eth0)"
1046 //usage: "\n -p FILE Create pidfile"
1047 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1048 //usage: "\n -B Request broadcast replies"
1049 //usage: "\n -t N Send up to N discover packets"
1050 //usage: "\n -T N Pause between packets (default 3 seconds)"
1051 //usage: "\n -A N Wait N seconds (default 20) after failure"
1052 //usage: "\n -f Run in foreground"
1053 //usage: USE_FOR_MMU(
1054 //usage: "\n -b Background if lease is not obtained"
1055 //usage: )
1056 //usage: "\n -n Exit if lease is not obtained"
1057 //usage: "\n -q Exit after obtaining lease"
1058 //usage: "\n -R Release IP on exit"
1059 //usage: "\n -S Log to syslog too"
1060 //usage: IF_FEATURE_UDHCP_PORT(
1061 //usage: "\n -P N Use port N (default 68)"
1062 //usage: )
1063 //usage: IF_FEATURE_UDHCPC_ARPING(
1064 //usage: "\n -a Use arping to validate offered address"
1065 //usage: )
1066 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1067 //usage: "\n -o Don't request any options (unless -O is given)"
1068 //usage: "\n -r IP Request this IP address"
1069 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1070 //usage: "\n Examples of string, numeric, and hex byte opts:"
1071 //usage: "\n -x hostname:bbox - option 12"
1072 //usage: "\n -x lease:3600 - option 51 (lease time)"
1073 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1074 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1075 //usage: "\n -H,-h NAME Send NAME as client hostname (default none)"
1076 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1077 //usage: "\n -C Don't send MAC as client identifier"
1078 //usage: IF_UDHCP_VERBOSE(
1079 //usage: "\n -v Verbose"
1080 //usage: )
1081 //usage: )
1082 //usage: "\nSignals:"
1083 //usage: "\n USR1 Renew current lease"
1084 //usage: "\n USR2 Release current lease"
1085
1086
1087 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1088 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1089 {
1090 uint8_t *temp, *message;
1091 const char *str_V, *str_h, *str_F, *str_r;
1092 IF_FEATURE_UDHCP_PORT(char *str_P;)
1093 void *clientid_mac_ptr;
1094 llist_t *list_O = NULL;
1095 llist_t *list_x = NULL;
1096 int tryagain_timeout = 20;
1097 int discover_timeout = 3;
1098 int discover_retries = 5;
1099 uint32_t server_addr = server_addr; /* for compiler */
1100 uint32_t requested_ip = 0;
1101 uint32_t xid = 0;
1102 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
1103 int packet_num;
1104 int timeout; /* must be signed */
1105 unsigned already_waited_sec;
1106 unsigned opt;
1107 int max_fd;
1108 int retval;
1109 struct timeval tv;
1110 struct dhcp_packet packet;
1111 fd_set rfds;
1112
1113 /* Default options */
1114 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1115 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1116 client_config.interface = "eth0";
1117 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1118 str_V = "udhcp "BB_VER;
1119
1120 /* Parse command line */
1121 /* O,x: list; -T,-t,-A take numeric param */
1122 opt_complementary = "O::x::T+:t+:A+"
1123 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1124 ":vv"
1125 #endif
1126 ;
1127 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1128 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1129 "m" // zzz
1130 USE_FOR_MMU("b")
1131 IF_FEATURE_UDHCPC_ARPING("a")
1132 IF_FEATURE_UDHCP_PORT("P:")
1133 "v"
1134 , &str_V, &str_h, &str_h, &str_F
1135 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1136 , &client_config.script /* s */
1137 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1138 , &list_O
1139 , &list_x
1140 IF_FEATURE_UDHCP_PORT(, &str_P)
1141 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1142 , &dhcp_verbose
1143 #endif
1144 );
1145 if (opt & (OPT_h|OPT_H))
1146 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1147 if (opt & OPT_F) {
1148 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1149 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1150 /* Flag bits: 0000NEOS
1151 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1152 * O: 1 = Server indicates to client that DNS has been updated regardless
1153 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1154 * not "host.domain.com". Format 0 is obsolete.
1155 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1156 * Two [0] bytes which follow are deprecated and must be 0.
1157 */
1158 client_config.fqdn[OPT_DATA + 0] = 0x1;
1159 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1160 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1161 }
1162 if (opt & OPT_r)
1163 requested_ip = inet_addr(str_r);
1164 #if ENABLE_FEATURE_UDHCP_PORT
1165 if (opt & OPT_P) {
1166 CLIENT_PORT = xatou16(str_P);
1167 SERVER_PORT = CLIENT_PORT - 1;
1168 }
1169 #endif
1170 if (opt & OPT_o)
1171 client_config.no_default_options = 1;
1172 while (list_O) {
1173 char *optstr = llist_pop(&list_O);
1174 unsigned n = udhcp_option_idx(optstr);
1175 n = dhcp_optflags[n].code;
1176 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1177 }
1178 while (list_x) {
1179 char *optstr = llist_pop(&list_x);
1180 char *colon = strchr(optstr, ':');
1181 if (colon)
1182 *colon = ' ';
1183 /* now it looks similar to udhcpd's config file line:
1184 * "optname optval", using the common routine: */
1185 udhcp_str2optset(optstr, &client_config.options);
1186 }
1187
1188 if (opt & OPT_m) // zzz
1189 minpkt = 1;
1190
1191 if (udhcp_read_interface(client_config.interface,
1192 &client_config.ifindex,
1193 NULL,
1194 client_config.client_mac,
1195 &client_config.client_mtu)
1196 ) {
1197 return 1;
1198 }
1199
1200 clientid_mac_ptr = NULL;
1201 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1202 /* not suppressed and not set, set the default client ID */
1203 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1204 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1205 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1206 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1207 }
1208 if (str_V[0] != '\0')
1209 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1210 #if !BB_MMU
1211 /* on NOMMU reexec (i.e., background) early */
1212 if (!(opt & OPT_f)) {
1213 bb_daemonize_or_rexec(0 /* flags */, argv);
1214 logmode = LOGMODE_NONE;
1215 }
1216 #endif
1217 if (opt & OPT_S) {
1218 openlog(applet_name, LOG_PID, LOG_DAEMON);
1219 logmode |= LOGMODE_SYSLOG;
1220 }
1221
1222 /* Make sure fd 0,1,2 are open */
1223 bb_sanitize_stdio();
1224 /* Equivalent of doing a fflush after every \n */
1225 setlinebuf(stdout);
1226 /* Create pidfile */
1227 write_pidfile(client_config.pidfile);
1228 /* Goes to stdout (unless NOMMU) and possibly syslog */
1229 bb_info_msg("%s (v"BB_VER") started", applet_name);
1230 /* Set up the signal pipe */
1231 udhcp_sp_setup();
1232 /* We want random_xid to be random... */
1233 srand(monotonic_us());
1234
1235 state = INIT_SELECTING;
1236 udhcp_run_script(NULL, "deconfig");
1237 change_listen_mode(LISTEN_RAW);
1238 packet_num = 0;
1239 timeout = 0;
1240 already_waited_sec = 0;
1241
1242 /* Main event loop. select() waits on signal pipe and possibly
1243 * on sockfd.
1244 * "continue" statements in code below jump to the top of the loop.
1245 */
1246 for (;;) {
1247 /* silence "uninitialized!" warning */
1248 unsigned timestamp_before_wait = timestamp_before_wait;
1249
1250 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1251
1252 /* Was opening raw or udp socket here
1253 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1254 * but on fast network renew responses return faster
1255 * than we open sockets. Thus this code is moved
1256 * to change_listen_mode(). Thus we open listen socket
1257 * BEFORE we send renew request (see "case BOUND:"). */
1258
1259 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1260
1261 tv.tv_sec = timeout - already_waited_sec;
1262 tv.tv_usec = 0;
1263 retval = 0;
1264 /* If we already timed out, fall through with retval = 0, else... */
1265 if ((int)tv.tv_sec > 0) {
1266 timestamp_before_wait = (unsigned)monotonic_sec();
1267 log1("Waiting on select...");
1268 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1269 if (retval < 0) {
1270 /* EINTR? A signal was caught, don't panic */
1271 if (errno == EINTR) {
1272 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1273 continue;
1274 }
1275 /* Else: an error occured, panic! */
1276 bb_perror_msg_and_die("select");
1277 }
1278 }
1279
1280 /* If timeout dropped to zero, time to become active:
1281 * resend discover/renew/whatever
1282 */
1283 if (retval == 0) {
1284 /* When running on a bridge, the ifindex may have changed
1285 * (e.g. if member interfaces were added/removed
1286 * or if the status of the bridge changed).
1287 * Refresh ifindex and client_mac:
1288 */
1289 if (udhcp_read_interface(client_config.interface,
1290 &client_config.ifindex,
1291 NULL,
1292 client_config.client_mac,
1293 &client_config.client_mtu)
1294 ) {
1295 return 1; /* iface is gone? */
1296 }
1297 if (clientid_mac_ptr)
1298 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1299
1300 /* We will restart the wait in any case */
1301 already_waited_sec = 0;
1302
1303 switch (state) {
1304 case INIT_SELECTING:
1305 if (packet_num < discover_retries) {
1306 if (packet_num == 0)
1307 xid = random_xid();
1308 /* broadcast */
1309 send_discover(xid, requested_ip);
1310 timeout = discover_timeout;
1311 packet_num++;
1312 continue;
1313 }
1314 leasefail:
1315 udhcp_run_script(NULL, "leasefail");
1316 #if BB_MMU /* -b is not supported on NOMMU */
1317 if (opt & OPT_b) { /* background if no lease */
1318 bb_info_msg("No lease, forking to background");
1319 client_background();
1320 /* do not background again! */
1321 opt = ((opt & ~OPT_b) | OPT_f);
1322 } else
1323 #endif
1324 if (opt & OPT_n) { /* abort if no lease */
1325 bb_info_msg("No lease, failing");
1326 retval = 1;
1327 goto ret;
1328 }
1329 /* wait before trying again */
1330 timeout = tryagain_timeout;
1331 packet_num = 0;
1332 continue;
1333 case REQUESTING:
1334 if (packet_num < discover_retries) {
1335 /* send broadcast select packet */
1336 send_select(xid, server_addr, requested_ip);
1337 timeout = discover_timeout;
1338 packet_num++;
1339 continue;
1340 }
1341 /* Timed out, go back to init state.
1342 * "discover...select...discover..." loops
1343 * were seen in the wild. Treat them similarly
1344 * to "no response to discover" case */
1345 change_listen_mode(LISTEN_RAW);
1346 state = INIT_SELECTING;
1347 goto leasefail;
1348 case BOUND:
1349 /* 1/2 lease passed, enter renewing state */
1350 state = RENEWING;
1351 client_config.first_secs = 0; /* make secs field count from 0 */
1352 change_listen_mode(LISTEN_RAW); // was: LISTEN_KERNEL -- zzz
1353 log1("Entering renew state");
1354 /* fall right through */
1355 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1356 case_RENEW_REQUESTED:
1357 case RENEWING:
1358 if (timeout > 60) {
1359 /* send an unicast renew request */
1360 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1361 * a new UDP socket for sending inside send_renew.
1362 * I hazard to guess existing listening socket
1363 * is somehow conflicting with it, but why is it
1364 * not deterministic then?! Strange.
1365 * Anyway, it does recover by eventually failing through
1366 * into INIT_SELECTING state.
1367 */
1368 send_renew(xid, server_addr, requested_ip);
1369 timeout >>= 1;
1370 continue;
1371 }
1372 /* Timed out, enter rebinding state */
1373 log1("Entering rebinding state");
1374 state = REBINDING;
1375 /* fall right through */
1376 case REBINDING:
1377 /* Switch to bcast receive */
1378 change_listen_mode(LISTEN_RAW);
1379 /* Lease is *really* about to run out,
1380 * try to find DHCP server using broadcast */
1381 if (timeout > 0) {
1382 /* send a broadcast renew request */
1383 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1384 timeout >>= 1;
1385 continue;
1386 }
1387 /* Timed out, enter init state */
1388 bb_info_msg("Lease lost, entering init state");
1389 udhcp_run_script(NULL, "deconfig");
1390 state = INIT_SELECTING;
1391 client_config.first_secs = 0; /* make secs field count from 0 */
1392 /*timeout = 0; - already is */
1393 packet_num = 0;
1394 continue;
1395 /* case RELEASED: */
1396 }
1397 /* yah, I know, *you* say it would never happen */
1398 timeout = INT_MAX;
1399 continue; /* back to main loop */
1400 } /* if select timed out */
1401
1402 /* select() didn't timeout, something happened */
1403
1404 /* Is it a signal? */
1405 /* note: udhcp_sp_read checks FD_ISSET before reading */
1406 switch (udhcp_sp_read(&rfds)) {
1407 case SIGUSR1:
1408 client_config.first_secs = 0; /* make secs field count from 0 */
1409 perform_renew();
1410 if (state == RENEW_REQUESTED)
1411 goto case_RENEW_REQUESTED;
1412 /* Start things over */
1413 packet_num = 0;
1414 /* Kill any timeouts, user wants this to hurry along */
1415 timeout = 0;
1416 continue;
1417 case SIGUSR2:
1418 perform_release(requested_ip, server_addr);
1419 timeout = INT_MAX;
1420 continue;
1421 case SIGTERM:
1422 bb_info_msg("Received SIGTERM");
1423 if (opt & OPT_R) /* release on quit */
1424 perform_release(requested_ip, server_addr);
1425 goto ret0;
1426 }
1427
1428 /* Is it a packet? */
1429 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1430 continue; /* no */
1431
1432 {
1433 int len;
1434
1435 /* A packet is ready, read it */
1436 if (listen_mode == LISTEN_KERNEL)
1437 len = udhcp_recv_kernel_packet(&packet, sockfd);
1438 else
1439 len = udhcp_recv_raw_packet(&packet, sockfd);
1440 if (len == -1) {
1441 /* Error is severe, reopen socket */
1442 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1443 sleep(discover_timeout); /* 3 seconds by default */
1444 change_listen_mode(listen_mode); /* just close and reopen */
1445 }
1446 /* If this packet will turn out to be unrelated/bogus,
1447 * we will go back and wait for next one.
1448 * Be sure timeout is properly decreased. */
1449 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1450 if (len < 0)
1451 continue;
1452 }
1453
1454 if (packet.xid != xid) {
1455 log1("xid %x (our is %x), ignoring packet",
1456 (unsigned)packet.xid, (unsigned)xid);
1457 continue;
1458 }
1459
1460 /* Ignore packets that aren't for us */
1461 if (packet.hlen != 6
1462 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1463 ) {
1464 //FIXME: need to also check that last 10 bytes are zero
1465 log1("chaddr does not match, ignoring packet"); // log2?
1466 continue;
1467 }
1468
1469 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1470 if (message == NULL) {
1471 bb_error_msg("no message type option, ignoring packet");
1472 continue;
1473 }
1474
1475 switch (state) {
1476 case INIT_SELECTING:
1477 /* Must be a DHCPOFFER to one of our xid's */
1478 if (*message == DHCPOFFER) {
1479 /* TODO: why we don't just fetch server's IP from IP header? */
1480 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1481 if (!temp) {
1482 bb_error_msg("no server ID, ignoring packet");
1483 continue;
1484 /* still selecting - this server looks bad */
1485 }
1486 /* it IS unaligned sometimes, don't "optimize" */
1487 move_from_unaligned32(server_addr, temp);
1488 /*xid = packet.xid; - already is */
1489 requested_ip = packet.yiaddr;
1490
1491 /* enter requesting state */
1492 state = REQUESTING;
1493 timeout = 0;
1494 packet_num = 0;
1495 already_waited_sec = 0;
1496 }
1497 continue;
1498 case REQUESTING:
1499 case RENEWING:
1500 case RENEW_REQUESTED:
1501 case REBINDING:
1502 if (*message == DHCPACK) {
1503 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1504 if (!temp) {
1505 bb_error_msg("no lease time with ACK, using 1 hour lease");
1506 lease_seconds = 60 * 60;
1507 } else {
1508 /* it IS unaligned sometimes, don't "optimize" */
1509 move_from_unaligned32(lease_seconds, temp);
1510 lease_seconds = ntohl(lease_seconds);
1511 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1512 if (lease_seconds < 10) /* and not too small */
1513 lease_seconds = 10;
1514 }
1515 #if ENABLE_FEATURE_UDHCPC_ARPING
1516 if (opt & OPT_a) {
1517 /* RFC 2131 3.1 paragraph 5:
1518 * "The client receives the DHCPACK message with configuration
1519 * parameters. The client SHOULD perform a final check on the
1520 * parameters (e.g., ARP for allocated network address), and notes
1521 * the duration of the lease specified in the DHCPACK message. At this
1522 * point, the client is configured. If the client detects that the
1523 * address is already in use (e.g., through the use of ARP),
1524 * the client MUST send a DHCPDECLINE message to the server and restarts
1525 * the configuration process..." */
1526 if (!arpping(packet.yiaddr,
1527 NULL,
1528 (uint32_t) 0,
1529 client_config.client_mac,
1530 client_config.interface)
1531 ) {
1532 bb_info_msg("Offered address is in use "
1533 "(got ARP reply), declining");
1534 send_decline(xid, server_addr, packet.yiaddr);
1535
1536 if (state != REQUESTING)
1537 udhcp_run_script(NULL, "deconfig");
1538 change_listen_mode(LISTEN_RAW);
1539 state = INIT_SELECTING;
1540 client_config.first_secs = 0; /* make secs field count from 0 */
1541 requested_ip = 0;
1542 timeout = tryagain_timeout;
1543 packet_num = 0;
1544 already_waited_sec = 0;
1545 continue; /* back to main loop */
1546 }
1547 }
1548 #endif
1549 /* enter bound state */
1550 timeout = lease_seconds / 2;
1551 {
1552 struct in_addr temp_addr;
1553 temp_addr.s_addr = packet.yiaddr;
1554 bb_info_msg("Lease of %s obtained, lease time %u",
1555 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1556 }
1557 requested_ip = packet.yiaddr;
1558 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1559
1560 state = BOUND;
1561 change_listen_mode(LISTEN_NONE);
1562 if (opt & OPT_q) { /* quit after lease */
1563 if (opt & OPT_R) /* release on quit */
1564 perform_release(requested_ip, server_addr);
1565 goto ret0;
1566 }
1567 /* future renew failures should not exit (JM) */
1568 opt &= ~OPT_n;
1569 #if BB_MMU /* NOMMU case backgrounded earlier */
1570 if (!(opt & OPT_f)) {
1571 client_background();
1572 /* do not background again! */
1573 opt = ((opt & ~OPT_b) | OPT_f);
1574 }
1575 #endif
1576 already_waited_sec = 0;
1577 continue; /* back to main loop */
1578 }
1579 if (*message == DHCPNAK) {
1580 /* return to init state */
1581 bb_info_msg("Received DHCP NAK");
1582 udhcp_run_script(&packet, "nak");
1583 if (state != REQUESTING)
1584 udhcp_run_script(NULL, "deconfig");
1585 change_listen_mode(LISTEN_RAW);
1586 sleep(3); /* avoid excessive network traffic */
1587 state = INIT_SELECTING;
1588 client_config.first_secs = 0; /* make secs field count from 0 */
1589 requested_ip = 0;
1590 timeout = 0;
1591 packet_num = 0;
1592 already_waited_sec = 0;
1593 }
1594 continue;
1595 /* case BOUND: - ignore all packets */
1596 /* case RELEASED: - ignore all packets */
1597 }
1598 /* back to main loop */
1599 } /* for (;;) - main loop ends */
1600
1601 ret0:
1602 retval = 0;
1603 ret:
1604 /*if (client_config.pidfile) - remove_pidfile has its own check */
1605 remove_pidfile(client_config.pidfile);
1606 return retval;
1607 }
Tomato firmware and modifications.