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Tomato RAF-RT-N Release 1.28.9013v1.1 t
[tomato.git] / release / src / router / busybox / networking / udhcp / dhcpc.c
blob7009ae101b609d4dbf4e38b88fa814b4585c23b6
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 #if ENABLE_FEATURE_UDHCP_RFC5969
137 static int sprint_nip6(char *dest, const char *pre, const uint8_t *ip)
138 {
139 int len = 0;
140 int off;
141 uint16_t word;
142
143 len += sprintf(dest, "%s", pre);
144
145 for (off = 0; off < 16; off += 2)
146 {
147 move_from_unaligned16(word, &ip[off]);
148 len += sprintf(dest+len, "%s%04X", off ? ":" : "", htons(word));
149 }
150
151 return len;
152 }
153 #endif
154
155 /* really simple implementation, just count the bits */
156 static int mton(uint32_t mask)
157 {
158 int i = 0;
159 mask = ntohl(mask); /* 111110000-like bit pattern */
160 while (mask) {
161 i++;
162 mask <<= 1;
163 }
164 return i;
165 }
166
167 /* Create "opt_name=opt_value" string */
168 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
169 {
170 unsigned upper_length;
171 int len, type, optlen;
172 char *dest, *ret;
173
174 /* option points to OPT_DATA, need to go back and get OPT_LEN */
175 len = option[OPT_LEN - OPT_DATA];
176
177 type = optflag->flags & OPTION_TYPE_MASK;
178 optlen = dhcp_option_lengths[type];
179 upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen);
180
181 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
182 dest += sprintf(ret, "%s=", opt_name);
183
184 while (len >= optlen) {
185 unsigned ip_ofs = 0;
186
187 switch (type) {
188 case OPTION_IP_PAIR:
189 dest += sprint_nip(dest, "", option);
190 *dest++ = '/';
191 ip_ofs = 4;
192 /* fall through */
193 case OPTION_IP:
194 dest += sprint_nip(dest, "", option + ip_ofs);
195 break;
196 // case OPTION_BOOLEAN:
197 // dest += sprintf(dest, *option ? "yes" : "no");
198 // break;
199 case OPTION_U8:
200 dest += sprintf(dest, "%u", *option);
201 break;
202 // case OPTION_S16:
203 case OPTION_U16: {
204 uint16_t val_u16;
205 move_from_unaligned16(val_u16, option);
206 dest += sprintf(dest, "%u", ntohs(val_u16));
207 break;
208 }
209 case OPTION_S32:
210 case OPTION_U32: {
211 uint32_t val_u32;
212 move_from_unaligned32(val_u32, option);
213 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
214 break;
215 }
216 case OPTION_STRING:
217 memcpy(dest, option, len);
218 dest[len] = '\0';
219 return ret; /* Short circuit this case */
220 case OPTION_STATIC_ROUTES: {
221 /* Option binary format:
222 * mask [one byte, 0..32]
223 * ip [big endian, 0..4 bytes depending on mask]
224 * router [big endian, 4 bytes]
225 * may be repeated
226 *
227 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
228 */
229 const char *pfx = "";
230
231 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
232 uint32_t nip;
233 uint8_t *p;
234 unsigned mask;
235 int bytes;
236
237 mask = *option++;
238 if (mask > 32)
239 break;
240 len--;
241
242 nip = 0;
243 p = (void*) &nip;
244 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
245 while (--bytes >= 0) {
246 *p++ = *option++;
247 len--;
248 }
249 if (len < 4)
250 break;
251
252 /* print ip/mask */
253 dest += sprint_nip(dest, pfx, (void*) &nip);
254 pfx = " ";
255 dest += sprintf(dest, "/%u ", mask);
256 /* print router */
257 dest += sprint_nip(dest, "", option);
258 option += 4;
259 len -= 4;
260 }
261
262 return ret;
263 }
264 #if ENABLE_FEATURE_UDHCP_RFC3397
265 case OPTION_DNS_STRING:
266 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
267 dest = dname_dec(option, len, ret);
268 if (dest) {
269 free(ret);
270 return dest;
271 }
272 /* error. return "optname=" string */
273 return ret;
274 case OPTION_SIP_SERVERS:
275 /* Option binary format:
276 * type: byte
277 * type=0: domain names, dns-compressed
278 * type=1: IP addrs
279 */
280 option++;
281 len--;
282 if (option[-1] == 0) {
283 dest = dname_dec(option, len, ret);
284 if (dest) {
285 free(ret);
286 return dest;
287 }
288 } else
289 if (option[-1] == 1) {
290 const char *pfx = "";
291 while (1) {
292 len -= 4;
293 if (len < 0)
294 break;
295 dest += sprint_nip(dest, pfx, option);
296 pfx = " ";
297 option += 4;
298 }
299 }
300 return ret;
301 #endif
302 #if ENABLE_FEATURE_UDHCP_RFC5969
303 case OPTION_6RD:
304 /* Option binary format:
305 * 0 1 2 3
306 * 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
307 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
308 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
309 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
310 * | |
311 * | 6rdPrefix |
312 * | (16 octets) |
313 * | |
314 * | |
315 * | |
316 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
317 * | 6rdBRIPv4Address(es) |
318 * . .
319 * . .
320 * . .
321 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
322 *
323 * We convert it to a string "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address"
324 */
325
326 /* Sanity check: ensure that our length is at least 22 bytes, that
327 * IPv4MaskLen is <= 32, 6rdPrefixLen <= 128 and that the sum of
328 * (32 - IPv4MaskLen) + 6rdPrefixLen is less than or equal to 128.
329 * If any of these requirements is not fulfilled, return with empty
330 * value.
331 */
332 if ((len >= 22) && (*option <= 32) && (*(option+1) <= 128) &&
333 (((32 - *option) + *(option+1)) <= 128))
334 {
335 /* IPv4MaskLen */
336 dest += sprintf(dest, "%u ", *option++);
337 len--;
338
339 /* 6rdPrefixLen */
340 dest += sprintf(dest, "%u ", *option++);
341 len--;
342
343 /* 6rdPrefix */
344 dest += sprint_nip6(dest, "", option);
345 option += 16;
346 len -= 16;
347
348 /* 6rdBRIPv4Addresses */
349 while (len >= 4)
350 {
351 dest += sprint_nip(dest, " ", option);
352 option += 4;
353 len -= 4;
354
355 /* the code to determine the option size fails to work with
356 * lengths that are not a multiple of the minimum length,
357 * adding all advertised 6rdBRIPv4Addresses here would
358 * overflow the destination buffer, therefore skip the rest
359 * for now
360 */
361 break;
362 }
363 }
364
365 return ret;
366 #endif
367 } /* switch */
368 option += optlen;
369 len -= optlen;
370 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
371 // Should we bail out/warn if we see multi-ip option which is
372 // not allowed to be such (for example, DHCP_BROADCAST)? -
373 if (len <= 0 /* || !(optflag->flags & OPTION_LIST) */)
374 break;
375 *dest++ = ' ';
376 *dest = '\0';
377 }
378 return ret;
379 }
380
381 /* put all the parameters into the environment */
382 static char **fill_envp(struct dhcp_packet *packet)
383 {
384 int envc;
385 int i;
386 char **envp, **curr;
387 const char *opt_name;
388 uint8_t *temp;
389 uint8_t overload = 0;
390
391 /* We need 6 elements for:
392 * "interface=IFACE"
393 * "ip=N.N.N.N" from packet->yiaddr
394 * "siaddr=IP" from packet->siaddr_nip (unless 0)
395 * "boot_file=FILE" from packet->file (unless overloaded)
396 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
397 * terminating NULL
398 */
399 envc = 6;
400 /* +1 element for each option, +2 for subnet option: */
401 if (packet) {
402 for (i = 0; dhcp_optflags[i].code; i++) {
403 if (udhcp_get_option(packet, dhcp_optflags[i].code)) {
404 if (dhcp_optflags[i].code == DHCP_SUBNET)
405 envc++; /* for mton */
406 envc++;
407 }
408 }
409 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
410 if (temp)
411 overload = *temp;
412 }
413 curr = envp = xzalloc(sizeof(char *) * envc);
414
415 *curr = xasprintf("interface=%s", client_config.interface);
416 putenv(*curr++);
417
418 if (!packet)
419 return envp;
420
421 *curr = xmalloc(sizeof("ip=255.255.255.255"));
422 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
423 putenv(*curr++);
424
425 opt_name = dhcp_option_strings;
426 i = 0;
427 while (*opt_name) {
428 temp = udhcp_get_option(packet, dhcp_optflags[i].code);
429 if (!temp)
430 goto next;
431 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
432 putenv(*curr++);
433 if (dhcp_optflags[i].code == DHCP_SUBNET) {
434 /* Subnet option: make things like "$ip/$mask" possible */
435 uint32_t subnet;
436 move_from_unaligned32(subnet, temp);
437 *curr = xasprintf("mask=%d", mton(subnet));
438 putenv(*curr++);
439 }
440 next:
441 opt_name += strlen(opt_name) + 1;
442 i++;
443 }
444 if (packet->siaddr_nip) {
445 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
446 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
447 putenv(*curr++);
448 }
449 if (!(overload & FILE_FIELD) && packet->file[0]) {
450 /* watch out for invalid packets */
451 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
452 putenv(*curr++);
453 }
454 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
455 /* watch out for invalid packets */
456 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
457 putenv(*curr++);
458 }
459 return envp;
460 }
461
462 /* Call a script with a par file and env vars */
463 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
464 {
465 char **envp, **curr;
466 char *argv[3];
467
468 if (client_config.script == NULL)
469 return;
470
471 envp = fill_envp(packet);
472
473 /* call script */
474 log1("Executing %s %s", client_config.script, name);
475 argv[0] = (char*) client_config.script;
476 argv[1] = (char*) name;
477 argv[2] = NULL;
478 spawn_and_wait(argv);
479
480 for (curr = envp; *curr; curr++) {
481 log2(" %s", *curr);
482 bb_unsetenv_and_free(*curr);
483 }
484 free(envp);
485 }
486
487
488 /*** Sending/receiving packets ***/
489
490 static ALWAYS_INLINE uint32_t random_xid(void)
491 {
492 return rand();
493 }
494
495 /* Initialize the packet with the proper defaults */
496 static void init_packet(struct dhcp_packet *packet, char type)
497 {
498 uint16_t secs;
499
500 /* Fill in: op, htype, hlen, cookie fields; message type option: */
501 udhcp_init_header(packet, type);
502
503 packet->xid = random_xid();
504
505 client_config.last_secs = monotonic_sec();
506 if (client_config.first_secs == 0)
507 client_config.first_secs = client_config.last_secs;
508 secs = client_config.last_secs - client_config.first_secs;
509 packet->secs = htons(secs);
510
511 memcpy(packet->chaddr, client_config.client_mac, 6);
512 if (client_config.clientid)
513 udhcp_add_binary_option(packet, client_config.clientid);
514 }
515
516 static void add_client_options(struct dhcp_packet *packet)
517 {
518 uint8_t c;
519 int i, end, len;
520
521 len = sizeof(struct ip_udp_dhcp_packet);
522 if (client_config.client_mtu == 0 ||
523 client_config.client_mtu > len)
524 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(len));
525
526 /* Add a "param req" option with the list of options we'd like to have
527 * from stubborn DHCP servers. Pull the data from the struct in common.c.
528 * No bounds checking because it goes towards the head of the packet. */
529 end = udhcp_end_option(packet->options);
530 len = 0;
531 for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
532 if (( (dhcp_optflags[i].flags & OPTION_REQ)
533 && !client_config.no_default_options
534 )
535 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
536 ) {
537 packet->options[end + OPT_DATA + len] = c;
538 len++;
539 }
540 }
541 if (len) {
542 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
543 packet->options[end + OPT_LEN] = len;
544 packet->options[end + OPT_DATA + len] = DHCP_END;
545 }
546
547 if (client_config.vendorclass)
548 udhcp_add_binary_option(packet, client_config.vendorclass);
549 if (client_config.hostname)
550 udhcp_add_binary_option(packet, client_config.hostname);
551 if (client_config.fqdn)
552 udhcp_add_binary_option(packet, client_config.fqdn);
553
554 /* Request broadcast replies if we have no IP addr */
555 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
556 packet->flags |= htons(BROADCAST_FLAG);
557
558 /* Add -x options if any */
559 {
560 struct option_set *curr = client_config.options;
561 while (curr) {
562 udhcp_add_binary_option(packet, curr->data);
563 curr = curr->next;
564 }
565 // if (client_config.sname)
566 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
567 // if (client_config.boot_file)
568 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
569 }
570 }
571
572 /* RFC 2131
573 * 4.4.4 Use of broadcast and unicast
574 *
575 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
576 * messages, unless the client knows the address of a DHCP server.
577 * The client unicasts DHCPRELEASE messages to the server. Because
578 * the client is declining the use of the IP address supplied by the server,
579 * the client broadcasts DHCPDECLINE messages.
580 *
581 * When the DHCP client knows the address of a DHCP server, in either
582 * INIT or REBOOTING state, the client may use that address
583 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
584 * The client may also use unicast to send DHCPINFORM messages
585 * to a known DHCP server. If the client receives no response to DHCP
586 * messages sent to the IP address of a known DHCP server, the DHCP
587 * client reverts to using the IP broadcast address.
588 */
589
590 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
591 {
592 return udhcp_send_raw_packet(packet,
593 /*src*/ INADDR_ANY, CLIENT_PORT,
594 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
595 client_config.ifindex);
596 }
597
598 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
599 /* NOINLINE: limit stack usage in caller */
600 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
601 {
602 struct dhcp_packet packet;
603 static int msgs = 0;
604
605 /* Fill in: op, htype, hlen, cookie, chaddr fields,
606 * random xid field (we override it below),
607 * client-id option (unless -C), message type option:
608 */
609 init_packet(&packet, DHCPDISCOVER);
610
611 packet.xid = xid;
612 if (requested)
613 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
614
615 /* Add options: maxsize,
616 * optionally: hostname, fqdn, vendorclass,
617 * "param req" option according to -O, options specified with -x
618 */
619 add_client_options(&packet);
620
621 if (msgs++ < 3)
622 bb_info_msg("Sending discover...");
623 return raw_bcast_from_client_config_ifindex(&packet);
624 }
625
626 /* Broadcast a DHCP request message */
627 /* RFC 2131 3.1 paragraph 3:
628 * "The client _broadcasts_ a DHCPREQUEST message..."
629 */
630 /* NOINLINE: limit stack usage in caller */
631 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
632 {
633 struct dhcp_packet packet;
634 struct in_addr addr;
635
636 /*
637 * RFC 2131 4.3.2 DHCPREQUEST message
638 * ...
639 * If the DHCPREQUEST message contains a 'server identifier'
640 * option, the message is in response to a DHCPOFFER message.
641 * Otherwise, the message is a request to verify or extend an
642 * existing lease. If the client uses a 'client identifier'
643 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
644 * in all subsequent messages. If the client included a list
645 * of requested parameters in a DHCPDISCOVER message, it MUST
646 * include that list in all subsequent messages.
647 */
648 /* Fill in: op, htype, hlen, cookie, chaddr fields,
649 * random xid field (we override it below),
650 * client-id option (unless -C), message type option:
651 */
652 init_packet(&packet, DHCPREQUEST);
653
654 packet.xid = xid;
655 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
656
657 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
658
659 /* Add options: maxsize,
660 * optionally: hostname, fqdn, vendorclass,
661 * "param req" option according to -O, and options specified with -x
662 */
663 add_client_options(&packet);
664
665 addr.s_addr = requested;
666 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
667 return raw_bcast_from_client_config_ifindex(&packet);
668 }
669
670 /* Unicast or broadcast a DHCP renew message */
671 /* NOINLINE: limit stack usage in caller */
672 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
673 {
674 struct dhcp_packet packet;
675
676 /*
677 * RFC 2131 4.3.2 DHCPREQUEST message
678 * ...
679 * DHCPREQUEST generated during RENEWING state:
680 *
681 * 'server identifier' MUST NOT be filled in, 'requested IP address'
682 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
683 * client's IP address. In this situation, the client is completely
684 * configured, and is trying to extend its lease. This message will
685 * be unicast, so no relay agents will be involved in its
686 * transmission. Because 'giaddr' is therefore not filled in, the
687 * DHCP server will trust the value in 'ciaddr', and use it when
688 * replying to the client.
689 */
690 /* Fill in: op, htype, hlen, cookie, chaddr fields,
691 * random xid field (we override it below),
692 * client-id option (unless -C), message type option:
693 */
694 init_packet(&packet, DHCPREQUEST);
695
696 packet.xid = xid;
697 packet.ciaddr = ciaddr;
698
699 /* Add options: maxsize,
700 * optionally: hostname, fqdn, vendorclass,
701 * "param req" option according to -O, and options specified with -x
702 */
703 add_client_options(&packet);
704
705 bb_info_msg("Sending renew...");
706 if (server)
707 return udhcp_send_kernel_packet(&packet,
708 ciaddr, CLIENT_PORT,
709 server, SERVER_PORT);
710 return raw_bcast_from_client_config_ifindex(&packet);
711 }
712
713 #if ENABLE_FEATURE_UDHCPC_ARPING
714 /* Broadcast a DHCP decline message */
715 /* NOINLINE: limit stack usage in caller */
716 static NOINLINE int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
717 {
718 struct dhcp_packet packet;
719
720 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
721 * client-id option (unless -C), message type option:
722 */
723 init_packet(&packet, DHCPDECLINE);
724
725 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
726 * but in case the server is buggy and wants DHCPDECLINE's xid
727 * to match the xid which started entire handshake,
728 * we use the same xid we used in initial DHCPDISCOVER:
729 */
730 packet.xid = xid;
731 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
732 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
733
734 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
735
736 bb_info_msg("Sending decline...");
737 return raw_bcast_from_client_config_ifindex(&packet);
738 }
739 #endif
740
741 /* Unicast a DHCP release message */
742 static int send_release(uint32_t server, uint32_t ciaddr)
743 {
744 struct dhcp_packet packet;
745
746 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
747 * client-id option (unless -C), message type option:
748 */
749 init_packet(&packet, DHCPRELEASE);
750
751 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
752 packet.ciaddr = ciaddr;
753
754 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
755
756 bb_info_msg("Sending release...");
757 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
758 }
759
760 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
761 /* NOINLINE: limit stack usage in caller */
762 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
763 {
764 int bytes;
765 struct ip_udp_dhcp_packet packet;
766 uint16_t check;
767
768 memset(&packet, 0, sizeof(packet));
769 bytes = safe_read(fd, &packet, sizeof(packet));
770 if (bytes < 0) {
771 log1("Packet read error, ignoring");
772 /* NB: possible down interface, etc. Caller should pause. */
773 return bytes; /* returns -1 */
774 }
775
776 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
777 log1("Packet is too short, ignoring");
778 return -2;
779 }
780
781 if (bytes < ntohs(packet.ip.tot_len)) {
782 /* packet is bigger than sizeof(packet), we did partial read */
783 log1("Oversized packet, ignoring");
784 return -2;
785 }
786
787 /* ignore any extra garbage bytes */
788 bytes = ntohs(packet.ip.tot_len);
789
790 /* make sure its the right packet for us, and that it passes sanity checks */
791 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
792 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
793 || packet.udp.dest != htons(CLIENT_PORT)
794 /* || bytes > (int) sizeof(packet) - can't happen */
795 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
796 ) {
797 log1("Unrelated/bogus packet, ignoring");
798 return -2;
799 }
800
801 /* verify IP checksum */
802 check = packet.ip.check;
803 packet.ip.check = 0;
804 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
805 log1("Bad IP header checksum, ignoring");
806 return -2;
807 }
808
809 /* verify UDP checksum. IP header has to be modified for this */
810 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
811 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
812 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
813 check = packet.udp.check;
814 packet.udp.check = 0;
815 if (check && check != udhcp_checksum(&packet, bytes)) {
816 log1("Packet with bad UDP checksum received, ignoring");
817 return -2;
818 }
819
820 memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
821
822 if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
823 bb_info_msg("Packet with bad magic, ignoring");
824 return -2;
825 }
826 log1("Got valid DHCP packet");
827 udhcp_dump_packet(dhcp_pkt);
828 return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
829 }
830
831
832 /*** Main ***/
833
834 static int sockfd = -1;
835
836 #define LISTEN_NONE 0
837 #define LISTEN_KERNEL 1
838 #define LISTEN_RAW 2
839 static smallint listen_mode;
840
841 /* initial state: (re)start DHCP negotiation */
842 #define INIT_SELECTING 0
843 /* discover was sent, DHCPOFFER reply received */
844 #define REQUESTING 1
845 /* select/renew was sent, DHCPACK reply received */
846 #define BOUND 2
847 /* half of lease passed, want to renew it by sending unicast renew requests */
848 #define RENEWING 3
849 /* renew requests were not answered, lease is almost over, send broadcast renew */
850 #define REBINDING 4
851 /* manually requested renew (SIGUSR1) */
852 #define RENEW_REQUESTED 5
853 /* release, possibly manually requested (SIGUSR2) */
854 #define RELEASED 6
855 static smallint state;
856
857 static int udhcp_raw_socket(int ifindex)
858 {
859 int fd;
860 struct sockaddr_ll sock;
861
862 /*
863 * Comment:
864 *
865 * I've selected not to see LL header, so BPF doesn't see it, too.
866 * The filter may also pass non-IP and non-ARP packets, but we do
867 * a more complete check when receiving the message in userspace.
868 *
869 * and filter shamelessly stolen from:
870 *
871 * http://www.flamewarmaster.de/software/dhcpclient/
872 *
873 * There are a few other interesting ideas on that page (look under
874 * "Motivation"). Use of netlink events is most interesting. Think
875 * of various network servers listening for events and reconfiguring.
876 * That would obsolete sending HUP signals and/or make use of restarts.
877 *
878 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
879 * License: GPL v2.
880 *
881 * TODO: make conditional?
882 */
883 static const struct sock_filter filter_instr[] = {
884 /* load 9th byte (protocol) */
885 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
886 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
887 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
888 /* L1: load halfword from offset 6 (flags and frag offset) */
889 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
890 /* jump to L4 if any bits in frag offset field are set, else to L2 */
891 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
892 /* L2: skip IP header (load index reg with header len) */
893 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
894 /* load udp destination port from halfword[header_len + 2] */
895 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
896 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
897 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
898 /* L3: accept packet */
899 BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
900 /* L4: discard packet */
901 BPF_STMT(BPF_RET|BPF_K, 0),
902 };
903 static const struct sock_fprog filter_prog = {
904 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
905 /* casting const away: */
906 .filter = (struct sock_filter *) filter_instr,
907 };
908
909 log1("Opening raw socket on ifindex %d", ifindex); //log2?
910
911 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
912 log1("Got raw socket fd %d", fd); //log2?
913
914 sock.sll_family = AF_PACKET;
915 sock.sll_protocol = htons(ETH_P_IP);
916 sock.sll_ifindex = ifindex;
917 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
918
919 if (CLIENT_PORT == 68) {
920 /* Use only if standard port is in use */
921 /* Ignoring error (kernel may lack support for this) */
922 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
923 sizeof(filter_prog)) >= 0)
924 log1("Attached filter to raw socket fd %d", fd); // log?
925 }
926
927 log1("Created raw socket");
928
929 return fd;
930 }
931
932 static void change_listen_mode(int new_mode)
933 {
934 log1("Entering listen mode: %s",
935 new_mode != LISTEN_NONE
936 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
937 : "none"
938 );
939
940 listen_mode = new_mode;
941 if (sockfd >= 0) {
942 close(sockfd);
943 sockfd = -1;
944 }
945 if (new_mode == LISTEN_KERNEL)
946 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
947 else if (new_mode != LISTEN_NONE)
948 sockfd = udhcp_raw_socket(client_config.ifindex);
949 /* else LISTEN_NONE: sockfd stays closed */
950 }
951
952 /* Called only on SIGUSR1 */
953 static void perform_renew(void)
954 {
955 bb_info_msg("Performing a DHCP renew");
956 switch (state) {
957 case BOUND:
958 change_listen_mode(LISTEN_RAW); // zzz
959 case RENEWING:
960 case REBINDING:
961 // state = RENEW_REQUESTED; // zzz
962 // break;
963 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
964 case REQUESTING:
965 case RELEASED:
966 change_listen_mode(LISTEN_RAW);
967 state = INIT_SELECTING;
968 break;
969 case INIT_SELECTING:
970 break;
971 }
972 }
973
974 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
975 {
976 char buffer[sizeof("255.255.255.255")];
977 struct in_addr temp_addr;
978
979 /* send release packet */
980 if (state == BOUND || state == RENEWING || state == REBINDING) {
981 temp_addr.s_addr = server_addr;
982 strcpy(buffer, inet_ntoa(temp_addr));
983 temp_addr.s_addr = requested_ip;
984 bb_info_msg("Unicasting a release of %s to %s",
985 inet_ntoa(temp_addr), buffer);
986 send_release(server_addr, requested_ip); /* unicast */
987 udhcp_run_script(NULL, "deconfig");
988 }
989 bb_info_msg("Entering released state");
990
991 change_listen_mode(LISTEN_NONE);
992 state = RELEASED;
993 }
994
995 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
996 {
997 uint8_t *storage;
998 int len = strnlen(str, 255);
999 storage = xzalloc(len + extra + OPT_DATA);
1000 storage[OPT_CODE] = code;
1001 storage[OPT_LEN] = len + extra;
1002 memcpy(storage + extra + OPT_DATA, str, len);
1003 return storage;
1004 }
1005
1006 #if BB_MMU
1007 static void client_background(void)
1008 {
1009 bb_daemonize(0);
1010 logmode &= ~LOGMODE_STDIO;
1011 /* rewrite pidfile, as our pid is different now */
1012 write_pidfile(client_config.pidfile);
1013 }
1014 #endif
1015
1016 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1017 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1018 //usage:#else
1019 //usage:# define IF_UDHCP_VERBOSE(...)
1020 //usage:#endif
1021 //usage:#define udhcpc_trivial_usage
1022 //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
1023 //usage: " [-H HOSTNAME] [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
1024 //usage:#define udhcpc_full_usage "\n"
1025 //usage: IF_LONG_OPTS(
1026 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1027 //usage: "\n -p,--pidfile FILE Create pidfile"
1028 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1029 //usage: "\n -B,--broadcast Request broadcast replies"
1030 //usage: "\n -t,--retries N Send up to N discover packets"
1031 //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
1032 //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
1033 //usage: "\n -f,--foreground Run in foreground"
1034 //usage: USE_FOR_MMU(
1035 //usage: "\n -b,--background Background if lease is not obtained"
1036 //usage: )
1037 //usage: "\n -n,--now Exit if lease is not obtained"
1038 //usage: "\n -q,--quit Exit after obtaining lease"
1039 //usage: "\n -R,--release Release IP on exit"
1040 //usage: "\n -S,--syslog Log to syslog too"
1041 //usage: IF_FEATURE_UDHCP_PORT(
1042 //usage: "\n -P,--client-port N Use port N (default 68)"
1043 //usage: )
1044 //usage: IF_FEATURE_UDHCPC_ARPING(
1045 //usage: "\n -a,--arping Use arping to validate offered address"
1046 //usage: )
1047 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1048 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1049 //usage: "\n -r,--request IP Request this IP address"
1050 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1051 //usage: "\n Examples of string, numeric, and hex byte opts:"
1052 //usage: "\n -x hostname:bbox - option 12"
1053 //usage: "\n -x lease:3600 - option 51 (lease time)"
1054 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1055 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1056 //usage: "\n -H,-h,--hostname NAME Send NAME as client hostname (default none)"
1057 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1058 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1059 //usage: IF_UDHCP_VERBOSE(
1060 //usage: "\n -v Verbose"
1061 //usage: )
1062 //usage: )
1063 //usage: IF_NOT_LONG_OPTS(
1064 //usage: "\n -i IFACE Interface to use (default eth0)"
1065 //usage: "\n -p FILE Create pidfile"
1066 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1067 //usage: "\n -B Request broadcast replies"
1068 //usage: "\n -t N Send up to N discover packets"
1069 //usage: "\n -T N Pause between packets (default 3 seconds)"
1070 //usage: "\n -A N Wait N seconds (default 20) after failure"
1071 //usage: "\n -f Run in foreground"
1072 //usage: USE_FOR_MMU(
1073 //usage: "\n -b Background if lease is not obtained"
1074 //usage: )
1075 //usage: "\n -n Exit if lease is not obtained"
1076 //usage: "\n -q Exit after obtaining lease"
1077 //usage: "\n -R Release IP on exit"
1078 //usage: "\n -S Log to syslog too"
1079 //usage: IF_FEATURE_UDHCP_PORT(
1080 //usage: "\n -P N Use port N (default 68)"
1081 //usage: )
1082 //usage: IF_FEATURE_UDHCPC_ARPING(
1083 //usage: "\n -a Use arping to validate offered address"
1084 //usage: )
1085 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1086 //usage: "\n -o Don't request any options (unless -O is given)"
1087 //usage: "\n -r IP Request this IP address"
1088 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1089 //usage: "\n Examples of string, numeric, and hex byte opts:"
1090 //usage: "\n -x hostname:bbox - option 12"
1091 //usage: "\n -x lease:3600 - option 51 (lease time)"
1092 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1093 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1094 //usage: "\n -H,-h NAME Send NAME as client hostname (default none)"
1095 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1096 //usage: "\n -C Don't send MAC as client identifier"
1097 //usage: IF_UDHCP_VERBOSE(
1098 //usage: "\n -v Verbose"
1099 //usage: )
1100 //usage: )
1101 //usage: "\nSignals:"
1102 //usage: "\n USR1 Renew current lease"
1103 //usage: "\n USR2 Release current lease"
1104
1105
1106 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1107 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1108 {
1109 uint8_t *temp, *message;
1110 const char *str_V, *str_h, *str_F, *str_r;
1111 IF_FEATURE_UDHCP_PORT(char *str_P;)
1112 void *clientid_mac_ptr;
1113 llist_t *list_O = NULL;
1114 llist_t *list_x = NULL;
1115 int tryagain_timeout = 20;
1116 int discover_timeout = 3;
1117 int discover_retries = 5;
1118 uint32_t server_addr = server_addr; /* for compiler */
1119 uint32_t requested_ip = 0;
1120 uint32_t xid = 0;
1121 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
1122 int packet_num;
1123 int timeout; /* must be signed */
1124 unsigned already_waited_sec;
1125 unsigned opt;
1126 int max_fd;
1127 int retval;
1128 struct timeval tv;
1129 struct dhcp_packet packet;
1130 fd_set rfds;
1131
1132 /* Default options */
1133 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1134 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1135 client_config.interface = "eth0";
1136 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1137 str_V = "udhcp "BB_VER;
1138
1139 /* Parse command line */
1140 /* O,x: list; -T,-t,-A take numeric param */
1141 opt_complementary = "O::x::T+:t+:A+"
1142 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1143 ":vv"
1144 #endif
1145 ;
1146 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1147 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1148 "m" // zzz
1149 USE_FOR_MMU("b")
1150 IF_FEATURE_UDHCPC_ARPING("a")
1151 IF_FEATURE_UDHCP_PORT("P:")
1152 "v"
1153 , &str_V, &str_h, &str_h, &str_F
1154 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1155 , &client_config.script /* s */
1156 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1157 , &list_O
1158 , &list_x
1159 IF_FEATURE_UDHCP_PORT(, &str_P)
1160 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1161 , &dhcp_verbose
1162 #endif
1163 );
1164 if (opt & (OPT_h|OPT_H))
1165 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1166 if (opt & OPT_F) {
1167 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1168 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1169 /* Flag bits: 0000NEOS
1170 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1171 * O: 1 = Server indicates to client that DNS has been updated regardless
1172 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1173 * not "host.domain.com". Format 0 is obsolete.
1174 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1175 * Two [0] bytes which follow are deprecated and must be 0.
1176 */
1177 client_config.fqdn[OPT_DATA + 0] = 0x1;
1178 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1179 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1180 }
1181 if (opt & OPT_r)
1182 requested_ip = inet_addr(str_r);
1183 #if ENABLE_FEATURE_UDHCP_PORT
1184 if (opt & OPT_P) {
1185 CLIENT_PORT = xatou16(str_P);
1186 SERVER_PORT = CLIENT_PORT - 1;
1187 }
1188 #endif
1189 if (opt & OPT_o)
1190 client_config.no_default_options = 1;
1191 while (list_O) {
1192 char *optstr = llist_pop(&list_O);
1193 unsigned n = udhcp_option_idx(optstr);
1194 n = dhcp_optflags[n].code;
1195 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1196 }
1197 while (list_x) {
1198 char *optstr = llist_pop(&list_x);
1199 char *colon = strchr(optstr, ':');
1200 if (colon)
1201 *colon = ' ';
1202 /* now it looks similar to udhcpd's config file line:
1203 * "optname optval", using the common routine: */
1204 udhcp_str2optset(optstr, &client_config.options);
1205 }
1206
1207 if (opt & OPT_m) // zzz
1208 minpkt = 1;
1209
1210 if (udhcp_read_interface(client_config.interface,
1211 &client_config.ifindex,
1212 NULL,
1213 client_config.client_mac,
1214 &client_config.client_mtu)
1215 ) {
1216 return 1;
1217 }
1218
1219 clientid_mac_ptr = NULL;
1220 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1221 /* not suppressed and not set, set the default client ID */
1222 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1223 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1224 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1225 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1226 }
1227 if (str_V[0] != '\0')
1228 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1229 #if !BB_MMU
1230 /* on NOMMU reexec (i.e., background) early */
1231 if (!(opt & OPT_f)) {
1232 bb_daemonize_or_rexec(0 /* flags */, argv);
1233 logmode = LOGMODE_NONE;
1234 }
1235 #endif
1236 if (opt & OPT_S) {
1237 openlog(applet_name, LOG_PID, LOG_DAEMON);
1238 logmode |= LOGMODE_SYSLOG;
1239 }
1240
1241 /* Make sure fd 0,1,2 are open */
1242 bb_sanitize_stdio();
1243 /* Equivalent of doing a fflush after every \n */
1244 setlinebuf(stdout);
1245 /* Create pidfile */
1246 write_pidfile(client_config.pidfile);
1247 /* Goes to stdout (unless NOMMU) and possibly syslog */
1248 bb_info_msg("%s (v"BB_VER") started", applet_name);
1249 /* Set up the signal pipe */
1250 udhcp_sp_setup();
1251 /* We want random_xid to be random... */
1252 srand(monotonic_us());
1253
1254 state = INIT_SELECTING;
1255 udhcp_run_script(NULL, "deconfig");
1256 change_listen_mode(LISTEN_RAW);
1257 packet_num = 0;
1258 timeout = 0;
1259 already_waited_sec = 0;
1260
1261 /* Main event loop. select() waits on signal pipe and possibly
1262 * on sockfd.
1263 * "continue" statements in code below jump to the top of the loop.
1264 */
1265 for (;;) {
1266 /* silence "uninitialized!" warning */
1267 unsigned timestamp_before_wait = timestamp_before_wait;
1268
1269 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1270
1271 /* Was opening raw or udp socket here
1272 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1273 * but on fast network renew responses return faster
1274 * than we open sockets. Thus this code is moved
1275 * to change_listen_mode(). Thus we open listen socket
1276 * BEFORE we send renew request (see "case BOUND:"). */
1277
1278 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1279
1280 tv.tv_sec = timeout - already_waited_sec;
1281 tv.tv_usec = 0;
1282 retval = 0;
1283 /* If we already timed out, fall through with retval = 0, else... */
1284 if ((int)tv.tv_sec > 0) {
1285 timestamp_before_wait = (unsigned)monotonic_sec();
1286 log1("Waiting on select...");
1287 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1288 if (retval < 0) {
1289 /* EINTR? A signal was caught, don't panic */
1290 if (errno == EINTR) {
1291 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1292 continue;
1293 }
1294 /* Else: an error occured, panic! */
1295 bb_perror_msg_and_die("select");
1296 }
1297 }
1298
1299 /* If timeout dropped to zero, time to become active:
1300 * resend discover/renew/whatever
1301 */
1302 if (retval == 0) {
1303 /* When running on a bridge, the ifindex may have changed
1304 * (e.g. if member interfaces were added/removed
1305 * or if the status of the bridge changed).
1306 * Refresh ifindex and client_mac:
1307 */
1308 if (udhcp_read_interface(client_config.interface,
1309 &client_config.ifindex,
1310 NULL,
1311 client_config.client_mac,
1312 &client_config.client_mtu)
1313 ) {
1314 return 1; /* iface is gone? */
1315 }
1316 if (clientid_mac_ptr)
1317 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1318
1319 /* We will restart the wait in any case */
1320 already_waited_sec = 0;
1321
1322 switch (state) {
1323 case INIT_SELECTING:
1324 if (packet_num < discover_retries) {
1325 if (packet_num == 0)
1326 xid = random_xid();
1327 /* broadcast */
1328 send_discover(xid, requested_ip);
1329 timeout = discover_timeout;
1330 packet_num++;
1331 continue;
1332 }
1333 leasefail:
1334 udhcp_run_script(NULL, "leasefail");
1335 #if BB_MMU /* -b is not supported on NOMMU */
1336 if (opt & OPT_b) { /* background if no lease */
1337 bb_info_msg("No lease, forking to background");
1338 client_background();
1339 /* do not background again! */
1340 opt = ((opt & ~OPT_b) | OPT_f);
1341 } else
1342 #endif
1343 if (opt & OPT_n) { /* abort if no lease */
1344 bb_info_msg("No lease, failing");
1345 retval = 1;
1346 goto ret;
1347 }
1348 /* wait before trying again */
1349 timeout = tryagain_timeout;
1350 packet_num = 0;
1351 continue;
1352 case REQUESTING:
1353 if (packet_num < discover_retries) {
1354 /* send broadcast select packet */
1355 send_select(xid, server_addr, requested_ip);
1356 timeout = discover_timeout;
1357 packet_num++;
1358 continue;
1359 }
1360 /* Timed out, go back to init state.
1361 * "discover...select...discover..." loops
1362 * were seen in the wild. Treat them similarly
1363 * to "no response to discover" case */
1364 change_listen_mode(LISTEN_RAW);
1365 state = INIT_SELECTING;
1366 goto leasefail;
1367 case BOUND:
1368 /* 1/2 lease passed, enter renewing state */
1369 state = RENEWING;
1370 client_config.first_secs = 0; /* make secs field count from 0 */
1371 change_listen_mode(LISTEN_RAW); // was: LISTEN_KERNEL -- zzz
1372 log1("Entering renew state");
1373 /* fall right through */
1374 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1375 case_RENEW_REQUESTED:
1376 case RENEWING:
1377 if (timeout > 60) {
1378 /* send an unicast renew request */
1379 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1380 * a new UDP socket for sending inside send_renew.
1381 * I hazard to guess existing listening socket
1382 * is somehow conflicting with it, but why is it
1383 * not deterministic then?! Strange.
1384 * Anyway, it does recover by eventually failing through
1385 * into INIT_SELECTING state.
1386 */
1387 send_renew(xid, server_addr, requested_ip);
1388 timeout >>= 1;
1389 continue;
1390 }
1391 /* Timed out, enter rebinding state */
1392 log1("Entering rebinding state");
1393 state = REBINDING;
1394 /* fall right through */
1395 case REBINDING:
1396 /* Switch to bcast receive */
1397 change_listen_mode(LISTEN_RAW);
1398 /* Lease is *really* about to run out,
1399 * try to find DHCP server using broadcast */
1400 if (timeout > 0) {
1401 /* send a broadcast renew request */
1402 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1403 timeout >>= 1;
1404 continue;
1405 }
1406 /* Timed out, enter init state */
1407 bb_info_msg("Lease lost, entering init state");
1408 udhcp_run_script(NULL, "deconfig");
1409 state = INIT_SELECTING;
1410 client_config.first_secs = 0; /* make secs field count from 0 */
1411 /*timeout = 0; - already is */
1412 packet_num = 0;
1413 continue;
1414 /* case RELEASED: */
1415 }
1416 /* yah, I know, *you* say it would never happen */
1417 timeout = INT_MAX;
1418 continue; /* back to main loop */
1419 } /* if select timed out */
1420
1421 /* select() didn't timeout, something happened */
1422
1423 /* Is it a signal? */
1424 /* note: udhcp_sp_read checks FD_ISSET before reading */
1425 switch (udhcp_sp_read(&rfds)) {
1426 case SIGUSR1:
1427 client_config.first_secs = 0; /* make secs field count from 0 */
1428 perform_renew();
1429 if (state == RENEW_REQUESTED)
1430 goto case_RENEW_REQUESTED;
1431 /* Start things over */
1432 packet_num = 0;
1433 /* Kill any timeouts, user wants this to hurry along */
1434 timeout = 0;
1435 continue;
1436 case SIGUSR2:
1437 perform_release(requested_ip, server_addr);
1438 timeout = INT_MAX;
1439 continue;
1440 case SIGTERM:
1441 bb_info_msg("Received SIGTERM");
1442 if (opt & OPT_R) /* release on quit */
1443 perform_release(requested_ip, server_addr);
1444 goto ret0;
1445 }
1446
1447 /* Is it a packet? */
1448 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1449 continue; /* no */
1450
1451 {
1452 int len;
1453
1454 /* A packet is ready, read it */
1455 if (listen_mode == LISTEN_KERNEL)
1456 len = udhcp_recv_kernel_packet(&packet, sockfd);
1457 else
1458 len = udhcp_recv_raw_packet(&packet, sockfd);
1459 if (len == -1) {
1460 /* Error is severe, reopen socket */
1461 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1462 sleep(discover_timeout); /* 3 seconds by default */
1463 change_listen_mode(listen_mode); /* just close and reopen */
1464 }
1465 /* If this packet will turn out to be unrelated/bogus,
1466 * we will go back and wait for next one.
1467 * Be sure timeout is properly decreased. */
1468 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1469 if (len < 0)
1470 continue;
1471 }
1472
1473 if (packet.xid != xid) {
1474 log1("xid %x (our is %x), ignoring packet",
1475 (unsigned)packet.xid, (unsigned)xid);
1476 continue;
1477 }
1478
1479 /* Ignore packets that aren't for us */
1480 if (packet.hlen != 6
1481 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1482 ) {
1483 //FIXME: need to also check that last 10 bytes are zero
1484 log1("chaddr does not match, ignoring packet"); // log2?
1485 continue;
1486 }
1487
1488 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1489 if (message == NULL) {
1490 bb_error_msg("no message type option, ignoring packet");
1491 continue;
1492 }
1493
1494 switch (state) {
1495 case INIT_SELECTING:
1496 /* Must be a DHCPOFFER to one of our xid's */
1497 if (*message == DHCPOFFER) {
1498 /* TODO: why we don't just fetch server's IP from IP header? */
1499 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1500 if (!temp) {
1501 bb_error_msg("no server ID, ignoring packet");
1502 continue;
1503 /* still selecting - this server looks bad */
1504 }
1505 /* it IS unaligned sometimes, don't "optimize" */
1506 move_from_unaligned32(server_addr, temp);
1507 /*xid = packet.xid; - already is */
1508 requested_ip = packet.yiaddr;
1509
1510 /* enter requesting state */
1511 state = REQUESTING;
1512 timeout = 0;
1513 packet_num = 0;
1514 already_waited_sec = 0;
1515 }
1516 continue;
1517 case REQUESTING:
1518 case RENEWING:
1519 case RENEW_REQUESTED:
1520 case REBINDING:
1521 if (*message == DHCPACK) {
1522 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1523 if (!temp) {
1524 bb_error_msg("no lease time with ACK, using 1 hour lease");
1525 lease_seconds = 60 * 60;
1526 } else {
1527 /* it IS unaligned sometimes, don't "optimize" */
1528 move_from_unaligned32(lease_seconds, temp);
1529 lease_seconds = ntohl(lease_seconds);
1530 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1531 if (lease_seconds < 10) /* and not too small */
1532 lease_seconds = 10;
1533 }
1534 #if ENABLE_FEATURE_UDHCPC_ARPING
1535 if (opt & OPT_a) {
1536 /* RFC 2131 3.1 paragraph 5:
1537 * "The client receives the DHCPACK message with configuration
1538 * parameters. The client SHOULD perform a final check on the
1539 * parameters (e.g., ARP for allocated network address), and notes
1540 * the duration of the lease specified in the DHCPACK message. At this
1541 * point, the client is configured. If the client detects that the
1542 * address is already in use (e.g., through the use of ARP),
1543 * the client MUST send a DHCPDECLINE message to the server and restarts
1544 * the configuration process..." */
1545 if (!arpping(packet.yiaddr,
1546 NULL,
1547 (uint32_t) 0,
1548 client_config.client_mac,
1549 client_config.interface)
1550 ) {
1551 bb_info_msg("Offered address is in use "
1552 "(got ARP reply), declining");
1553 send_decline(xid, server_addr, packet.yiaddr);
1554
1555 if (state != REQUESTING)
1556 udhcp_run_script(NULL, "deconfig");
1557 change_listen_mode(LISTEN_RAW);
1558 state = INIT_SELECTING;
1559 client_config.first_secs = 0; /* make secs field count from 0 */
1560 requested_ip = 0;
1561 timeout = tryagain_timeout;
1562 packet_num = 0;
1563 already_waited_sec = 0;
1564 continue; /* back to main loop */
1565 }
1566 }
1567 #endif
1568 /* enter bound state */
1569 timeout = lease_seconds / 2;
1570 {
1571 struct in_addr temp_addr;
1572 temp_addr.s_addr = packet.yiaddr;
1573 bb_info_msg("Lease of %s obtained, lease time %u",
1574 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1575 }
1576 requested_ip = packet.yiaddr;
1577 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1578
1579 state = BOUND;
1580 change_listen_mode(LISTEN_NONE);
1581 if (opt & OPT_q) { /* quit after lease */
1582 if (opt & OPT_R) /* release on quit */
1583 perform_release(requested_ip, server_addr);
1584 goto ret0;
1585 }
1586 /* future renew failures should not exit (JM) */
1587 opt &= ~OPT_n;
1588 #if BB_MMU /* NOMMU case backgrounded earlier */
1589 if (!(opt & OPT_f)) {
1590 client_background();
1591 /* do not background again! */
1592 opt = ((opt & ~OPT_b) | OPT_f);
1593 }
1594 #endif
1595 already_waited_sec = 0;
1596 continue; /* back to main loop */
1597 }
1598 if (*message == DHCPNAK) {
1599 /* return to init state */
1600 bb_info_msg("Received DHCP NAK");
1601 udhcp_run_script(&packet, "nak");
1602 if (state != REQUESTING)
1603 udhcp_run_script(NULL, "deconfig");
1604 change_listen_mode(LISTEN_RAW);
1605 sleep(3); /* avoid excessive network traffic */
1606 state = INIT_SELECTING;
1607 client_config.first_secs = 0; /* make secs field count from 0 */
1608 requested_ip = 0;
1609 timeout = 0;
1610 packet_num = 0;
1611 already_waited_sec = 0;
1612 }
1613 continue;
1614 /* case BOUND: - ignore all packets */
1615 /* case RELEASED: - ignore all packets */
1616 }
1617 /* back to main loop */
1618 } /* for (;;) - main loop ends */
1619
1620 ret0:
1621 retval = 0;
1622 ret:
1623 /*if (client_config.pidfile) - remove_pidfile has its own check */
1624 remove_pidfile(client_config.pidfile);
1625 return retval;
1626 }
Tomato firmware and modifications.