blob: 56116d01ff8a762ead860833259d55db6e10e543 [file] [log] [blame]
"Robert P. J. Day"63fc1a92006-07-02 19:47:05 +00001/* vi: set sw=4 ts=4: */
Denys Vlasenko8a7c1662010-03-20 03:48:11 +01002/*
Denys Vlasenko385b4562010-03-26 10:09:34 +01003 * udhcp server
Mike Frysinger7031f622006-05-08 03:20:50 +00004 * Copyright (C) 1999 Matthew Ramsay <matthewr@moreton.com.au>
5 * Chris Trew <ctrew@moreton.com.au>
6 *
7 * Rewrite by Russ Dill <Russ.Dill@asu.edu> July 2001
8 *
Denys Vlasenko8a7c1662010-03-20 03:48:11 +01009 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License
20 * along with this program; if not, write to the Free Software
21 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
Mike Frysinger7031f622006-05-08 03:20:50 +000022 */
Pere Orga5bc8c002011-04-11 03:29:49 +020023
24//usage:#define udhcpd_trivial_usage
Denys Vlasenko7b5d5c12013-03-14 02:18:52 +010025//usage: "[-fS] [-I ADDR]" IF_FEATURE_UDHCP_PORT(" [-P N]") " [CONFFILE]"
Pere Orga5bc8c002011-04-11 03:29:49 +020026//usage:#define udhcpd_full_usage "\n\n"
27//usage: "DHCP server\n"
28//usage: "\n -f Run in foreground"
29//usage: "\n -S Log to syslog too"
Denys Vlasenkoe3f5b732013-03-13 22:27:37 +010030//usage: "\n -I ADDR Local address"
Michel Stam9f412712014-10-30 11:59:04 +010031//usage: "\n -a MSEC Timeout for ARP ping (default 2000)"
Pere Orga5bc8c002011-04-11 03:29:49 +020032//usage: IF_FEATURE_UDHCP_PORT(
33//usage: "\n -P N Use port N (default 67)"
34//usage: )
35
Denys Vlasenko2bf29312016-10-04 00:37:50 +020036#include <netinet/ether.h>
Denis Vlasenkoaf1c8432007-03-26 13:22:35 +000037#include <syslog.h>
Mike Frysinger7031f622006-05-08 03:20:50 +000038#include "common.h"
Denis Vlasenkod55fe3e2008-02-04 13:12:16 +000039#include "dhcpc.h"
Denis Vlasenko5a3395b2006-11-18 19:51:32 +000040#include "dhcpd.h"
Mike Frysinger7031f622006-05-08 03:20:50 +000041
Denys Vlasenkoa85740c2016-10-04 00:51:38 +020042/* globals */
43struct dyn_lease *g_leases;
44/* struct server_config_t server_config is in bb_common_bufsiz1 */
45
Denys Vlasenkod2ae66c2016-10-04 00:43:14 +020046/* Takes the address of the pointer to the static_leases linked list,
47 * address to a 6 byte mac address,
48 * 4 byte IP address */
49static void add_static_lease(struct static_lease **st_lease_pp,
50 uint8_t *mac,
51 uint32_t nip)
52{
53 struct static_lease *st_lease;
54
55 /* Find the tail of the list */
56 while ((st_lease = *st_lease_pp) != NULL) {
57 st_lease_pp = &st_lease->next;
58 }
59
60 /* Add new node */
61 *st_lease_pp = st_lease = xzalloc(sizeof(*st_lease));
62 memcpy(st_lease->mac, mac, 6);
63 st_lease->nip = nip;
64 /*st_lease->next = NULL;*/
65}
66
67/* Find static lease IP by mac */
68static uint32_t get_static_nip_by_mac(struct static_lease *st_lease, void *mac)
69{
70 while (st_lease) {
71 if (memcmp(st_lease->mac, mac, 6) == 0)
72 return st_lease->nip;
73 st_lease = st_lease->next;
74 }
75
76 return 0;
77}
78
Denys Vlasenkoa85740c2016-10-04 00:51:38 +020079static int is_nip_reserved(struct static_lease *st_lease, uint32_t nip)
80{
81 while (st_lease) {
82 if (st_lease->nip == nip)
83 return 1;
84 st_lease = st_lease->next;
85 }
86
87 return 0;
88}
89
Denys Vlasenkod2ae66c2016-10-04 00:43:14 +020090#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 2
91/* Print out static leases just to check what's going on */
92/* Takes the address of the pointer to the static_leases linked list */
93static void log_static_leases(struct static_lease **st_lease_pp)
94{
95 struct static_lease *cur;
96
97 if (dhcp_verbose < 2)
98 return;
99
100 cur = *st_lease_pp;
101 while (cur) {
102 bb_error_msg("static lease: mac:%02x:%02x:%02x:%02x:%02x:%02x nip:%x",
103 cur->mac[0], cur->mac[1], cur->mac[2],
104 cur->mac[3], cur->mac[4], cur->mac[5],
105 cur->nip
106 );
107 cur = cur->next;
108 }
109}
110#else
111# define log_static_leases(st_lease_pp) ((void)0)
112#endif
113
Denys Vlasenkoa85740c2016-10-04 00:51:38 +0200114/* Find the oldest expired lease, NULL if there are no expired leases */
115static struct dyn_lease *oldest_expired_lease(void)
116{
117 struct dyn_lease *oldest_lease = NULL;
118 leasetime_t oldest_time = time(NULL);
119 unsigned i;
120
121 /* Unexpired leases have g_leases[i].expires >= current time
122 * and therefore can't ever match */
123 for (i = 0; i < server_config.max_leases; i++) {
124 if (g_leases[i].expires == 0 /* empty entry */
125 || g_leases[i].expires < oldest_time
126 ) {
127 oldest_time = g_leases[i].expires;
128 oldest_lease = &g_leases[i];
129 }
130 }
131 return oldest_lease;
132}
133
134/* Clear out all leases with matching nonzero chaddr OR yiaddr.
135 * If chaddr == NULL, this is a conflict lease.
136 */
137static void clear_leases(const uint8_t *chaddr, uint32_t yiaddr)
138{
139 unsigned i;
140
141 for (i = 0; i < server_config.max_leases; i++) {
142 if ((chaddr && memcmp(g_leases[i].lease_mac, chaddr, 6) == 0)
143 || (yiaddr && g_leases[i].lease_nip == yiaddr)
144 ) {
145 memset(&g_leases[i], 0, sizeof(g_leases[i]));
146 }
147 }
148}
149
150/* Add a lease into the table, clearing out any old ones.
151 * If chaddr == NULL, this is a conflict lease.
152 */
153static struct dyn_lease *add_lease(
154 const uint8_t *chaddr, uint32_t yiaddr,
155 leasetime_t leasetime,
156 const char *hostname, int hostname_len)
157{
158 struct dyn_lease *oldest;
159
160 /* clean out any old ones */
161 clear_leases(chaddr, yiaddr);
162
163 oldest = oldest_expired_lease();
164
165 if (oldest) {
166 memset(oldest, 0, sizeof(*oldest));
167 if (hostname) {
168 char *p;
169
170 hostname_len++; /* include NUL */
171 if (hostname_len > sizeof(oldest->hostname))
172 hostname_len = sizeof(oldest->hostname);
173 p = safe_strncpy(oldest->hostname, hostname, hostname_len);
174 /*
175 * Sanitization (s/bad_char/./g).
176 * The intent is not to allow only "DNS-valid" hostnames,
177 * but merely make dumpleases output safe for shells to use.
178 * We accept "0-9A-Za-z._-", all other chars turn to dots.
179 */
180 while (*p) {
181 if (!isalnum(*p) && *p != '-' && *p != '_')
182 *p = '.';
183 p++;
184 }
185 }
186 if (chaddr)
187 memcpy(oldest->lease_mac, chaddr, 6);
188 oldest->lease_nip = yiaddr;
189 oldest->expires = time(NULL) + leasetime;
190 }
191
192 return oldest;
193}
194
195/* True if a lease has expired */
196static int is_expired_lease(struct dyn_lease *lease)
197{
198 return (lease->expires < (leasetime_t) time(NULL));
199}
200
201/* Find the first lease that matches MAC, NULL if no match */
202static struct dyn_lease *find_lease_by_mac(const uint8_t *mac)
203{
204 unsigned i;
205
206 for (i = 0; i < server_config.max_leases; i++)
207 if (memcmp(g_leases[i].lease_mac, mac, 6) == 0)
208 return &g_leases[i];
209
210 return NULL;
211}
212
213/* Find the first lease that matches IP, NULL is no match */
214static struct dyn_lease *find_lease_by_nip(uint32_t nip)
215{
216 unsigned i;
217
218 for (i = 0; i < server_config.max_leases; i++)
219 if (g_leases[i].lease_nip == nip)
220 return &g_leases[i];
221
222 return NULL;
223}
224
225/* Check if the IP is taken; if it is, add it to the lease table */
226static int nobody_responds_to_arp(uint32_t nip, const uint8_t *safe_mac, unsigned arpping_ms)
227{
228 struct in_addr temp;
229 int r;
230
231 r = arpping(nip, safe_mac,
232 server_config.server_nip,
233 server_config.server_mac,
234 server_config.interface,
235 arpping_ms);
236 if (r)
237 return r;
238
239 temp.s_addr = nip;
240 bb_error_msg("%s belongs to someone, reserving it for %u seconds",
241 inet_ntoa(temp), (unsigned)server_config.conflict_time);
242 add_lease(NULL, nip, server_config.conflict_time, NULL, 0);
243 return 0;
244}
245
246/* Find a new usable (we think) address */
247static uint32_t find_free_or_expired_nip(const uint8_t *safe_mac, unsigned arpping_ms)
248{
249 uint32_t addr;
250 struct dyn_lease *oldest_lease = NULL;
251
252#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
253 uint32_t stop;
254 unsigned i, hash;
255
256 /* hash hwaddr: use the SDBM hashing algorithm. Seems to give good
257 * dispersal even with similarly-valued "strings".
258 */
259 hash = 0;
260 for (i = 0; i < 6; i++)
261 hash += safe_mac[i] + (hash << 6) + (hash << 16) - hash;
262
263 /* pick a seed based on hwaddr then iterate until we find a free address. */
264 addr = server_config.start_ip
265 + (hash % (1 + server_config.end_ip - server_config.start_ip));
266 stop = addr;
267#else
268 addr = server_config.start_ip;
269#define stop (server_config.end_ip + 1)
270#endif
271 do {
272 uint32_t nip;
273 struct dyn_lease *lease;
274
275 /* ie, 192.168.55.0 */
276 if ((addr & 0xff) == 0)
277 goto next_addr;
278 /* ie, 192.168.55.255 */
279 if ((addr & 0xff) == 0xff)
280 goto next_addr;
281 nip = htonl(addr);
282 /* skip our own address */
283 if (nip == server_config.server_nip)
284 goto next_addr;
285 /* is this a static lease addr? */
286 if (is_nip_reserved(server_config.static_leases, nip))
287 goto next_addr;
288
289 lease = find_lease_by_nip(nip);
290 if (!lease) {
291//TODO: DHCP servers do not always sit on the same subnet as clients: should *ping*, not arp-ping!
292 if (nobody_responds_to_arp(nip, safe_mac, arpping_ms))
293 return nip;
294 } else {
295 if (!oldest_lease || lease->expires < oldest_lease->expires)
296 oldest_lease = lease;
297 }
298
299 next_addr:
300 addr++;
301#if ENABLE_FEATURE_UDHCPD_BASE_IP_ON_MAC
302 if (addr > server_config.end_ip)
303 addr = server_config.start_ip;
304#endif
305 } while (addr != stop);
306
307 if (oldest_lease
308 && is_expired_lease(oldest_lease)
309 && nobody_responds_to_arp(oldest_lease->lease_nip, safe_mac, arpping_ms)
310 ) {
311 return oldest_lease->lease_nip;
312 }
313
314 return 0;
315}
316
Denys Vlasenkod2ae66c2016-10-04 00:43:14 +0200317/* On these functions, make sure your datatype matches */
Denys Vlasenko2bf29312016-10-04 00:37:50 +0200318static int FAST_FUNC read_str(const char *line, void *arg)
319{
320 char **dest = arg;
321
322 free(*dest);
323 *dest = xstrdup(line);
324 return 1;
325}
326
327static int FAST_FUNC read_u32(const char *line, void *arg)
328{
329 *(uint32_t*)arg = bb_strtou32(line, NULL, 10);
330 return errno == 0;
331}
332
333static int FAST_FUNC read_staticlease(const char *const_line, void *arg)
334{
335 char *line;
336 char *mac_string;
337 char *ip_string;
338 struct ether_addr mac_bytes; /* it's "struct { uint8_t mac[6]; }" */
339 uint32_t nip;
340
341 /* Read mac */
342 line = (char *) const_line;
343 mac_string = strtok_r(line, " \t", &line);
344 if (!mac_string || !ether_aton_r(mac_string, &mac_bytes))
345 return 0;
346
347 /* Read ip */
348 ip_string = strtok_r(NULL, " \t", &line);
349 if (!ip_string || !udhcp_str2nip(ip_string, &nip))
350 return 0;
351
352 add_static_lease(arg, (uint8_t*) &mac_bytes, nip);
353
354 log_static_leases(arg);
355
356 return 1;
357}
358
359struct config_keyword {
360 const char *keyword;
361 int (*handler)(const char *line, void *var) FAST_FUNC;
362 unsigned ofs;
363 const char *def;
364};
365
366#define OFS(field) offsetof(struct server_config_t, field)
367
368static const struct config_keyword keywords[] = {
369 /* keyword handler variable address default */
370 {"start" , udhcp_str2nip , OFS(start_ip ), "192.168.0.20"},
371 {"end" , udhcp_str2nip , OFS(end_ip ), "192.168.0.254"},
372 {"interface" , read_str , OFS(interface ), "eth0"},
373 /* Avoid "max_leases value not sane" warning by setting default
374 * to default_end_ip - default_start_ip + 1: */
375 {"max_leases" , read_u32 , OFS(max_leases ), "235"},
376 {"auto_time" , read_u32 , OFS(auto_time ), "7200"},
377 {"decline_time" , read_u32 , OFS(decline_time ), "3600"},
378 {"conflict_time", read_u32 , OFS(conflict_time), "3600"},
379 {"offer_time" , read_u32 , OFS(offer_time ), "60"},
380 {"min_lease" , read_u32 , OFS(min_lease_sec), "60"},
381 {"lease_file" , read_str , OFS(lease_file ), LEASES_FILE},
382 {"pidfile" , read_str , OFS(pidfile ), "/var/run/udhcpd.pid"},
383 {"siaddr" , udhcp_str2nip , OFS(siaddr_nip ), "0.0.0.0"},
384 /* keywords with no defaults must be last! */
385 {"option" , udhcp_str2optset, OFS(options ), ""},
386 {"opt" , udhcp_str2optset, OFS(options ), ""},
387 {"notify_file" , read_str , OFS(notify_file ), NULL},
388 {"sname" , read_str , OFS(sname ), NULL},
389 {"boot_file" , read_str , OFS(boot_file ), NULL},
390 {"static_lease" , read_staticlease, OFS(static_leases), ""},
391};
392enum { KWS_WITH_DEFAULTS = ARRAY_SIZE(keywords) - 6 };
393
394static NOINLINE void read_config(const char *file)
395{
396 parser_t *parser;
397 const struct config_keyword *k;
398 unsigned i;
399 char *token[2];
400
401 for (i = 0; i < KWS_WITH_DEFAULTS; i++)
402 keywords[i].handler(keywords[i].def, (char*)&server_config + keywords[i].ofs);
403
404 parser = config_open(file);
405 while (config_read(parser, token, 2, 2, "# \t", PARSE_NORMAL)) {
406 for (k = keywords, i = 0; i < ARRAY_SIZE(keywords); k++, i++) {
407 if (strcasecmp(token[0], k->keyword) == 0) {
408 if (!k->handler(token[1], (char*)&server_config + k->ofs)) {
409 bb_error_msg("can't parse line %u in %s",
410 parser->lineno, file);
411 /* reset back to the default value */
412 k->handler(k->def, (char*)&server_config + k->ofs);
413 }
414 break;
415 }
416 }
417 }
418 config_close(parser);
419
420 server_config.start_ip = ntohl(server_config.start_ip);
421 server_config.end_ip = ntohl(server_config.end_ip);
422}
423
424static void write_leases(void)
425{
426 int fd;
427 unsigned i;
428 leasetime_t curr;
429 int64_t written_at;
430
431 fd = open_or_warn(server_config.lease_file, O_WRONLY|O_CREAT|O_TRUNC);
432 if (fd < 0)
433 return;
434
435 curr = written_at = time(NULL);
436
437 written_at = SWAP_BE64(written_at);
438 full_write(fd, &written_at, sizeof(written_at));
439
440 for (i = 0; i < server_config.max_leases; i++) {
441 leasetime_t tmp_time;
442
443 if (g_leases[i].lease_nip == 0)
444 continue;
445
446 /* Screw with the time in the struct, for easier writing */
447 tmp_time = g_leases[i].expires;
448
449 g_leases[i].expires -= curr;
450 if ((signed_leasetime_t) g_leases[i].expires < 0)
451 g_leases[i].expires = 0;
452 g_leases[i].expires = htonl(g_leases[i].expires);
453
454 /* No error check. If the file gets truncated,
455 * we lose some leases on restart. Oh well. */
456 full_write(fd, &g_leases[i], sizeof(g_leases[i]));
457
458 /* Then restore it when done */
459 g_leases[i].expires = tmp_time;
460 }
461 close(fd);
462
463 if (server_config.notify_file) {
464 char *argv[3];
465 argv[0] = server_config.notify_file;
466 argv[1] = server_config.lease_file;
467 argv[2] = NULL;
468 spawn_and_wait(argv);
469 }
470}
471
472static NOINLINE void read_leases(const char *file)
473{
474 struct dyn_lease lease;
475 int64_t written_at, time_passed;
476 int fd;
477#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
478 unsigned i = 0;
479#endif
480
481 fd = open_or_warn(file, O_RDONLY);
482 if (fd < 0)
483 return;
484
485 if (full_read(fd, &written_at, sizeof(written_at)) != sizeof(written_at))
486 goto ret;
487 written_at = SWAP_BE64(written_at);
488
489 time_passed = time(NULL) - written_at;
490 /* Strange written_at, or lease file from old version of udhcpd
491 * which had no "written_at" field? */
492 if ((uint64_t)time_passed > 12 * 60 * 60)
493 goto ret;
494
495 while (full_read(fd, &lease, sizeof(lease)) == sizeof(lease)) {
496 uint32_t y = ntohl(lease.lease_nip);
497 if (y >= server_config.start_ip && y <= server_config.end_ip) {
498 signed_leasetime_t expires = ntohl(lease.expires) - (signed_leasetime_t)time_passed;
499 uint32_t static_nip;
500
501 if (expires <= 0)
502 /* We keep expired leases: add_lease() will add
503 * a lease with 0 seconds remaining.
504 * Fewer IP address changes this way for mass reboot scenario.
505 */
506 expires = 0;
507
508 /* Check if there is a different static lease for this IP or MAC */
509 static_nip = get_static_nip_by_mac(server_config.static_leases, lease.lease_mac);
510 if (static_nip) {
511 /* NB: we do not add lease even if static_nip == lease.lease_nip.
512 */
513 continue;
514 }
515 if (is_nip_reserved(server_config.static_leases, lease.lease_nip))
516 continue;
517
518 /* NB: add_lease takes "relative time", IOW,
519 * lease duration, not lease deadline. */
520 if (add_lease(lease.lease_mac, lease.lease_nip,
521 expires,
522 lease.hostname, sizeof(lease.hostname)
523 ) == 0
524 ) {
525 bb_error_msg("too many leases while loading %s", file);
526 break;
527 }
528#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
529 i++;
530#endif
531 }
532 }
533 log1("read %d leases", i);
534 ret:
535 close(fd);
536}
Mike Frysinger7031f622006-05-08 03:20:50 +0000537
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100538/* Send a packet to a specific mac address and ip address by creating our own ip packet */
539static void send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100540{
541 const uint8_t *chaddr;
542 uint32_t ciaddr;
543
544 // Was:
545 //if (force_broadcast) { /* broadcast */ }
546 //else if (dhcp_pkt->ciaddr) { /* unicast to dhcp_pkt->ciaddr */ }
547 //else if (dhcp_pkt->flags & htons(BROADCAST_FLAG)) { /* broadcast */ }
548 //else { /* unicast to dhcp_pkt->yiaddr */ }
549 // But this is wrong: yiaddr is _our_ idea what client's IP is
550 // (for example, from lease file). Client may not know that,
551 // and may not have UDP socket listening on that IP!
552 // We should never unicast to dhcp_pkt->yiaddr!
553 // dhcp_pkt->ciaddr, OTOH, comes from client's request packet,
554 // and can be used.
555
556 if (force_broadcast
557 || (dhcp_pkt->flags & htons(BROADCAST_FLAG))
Denys Vlasenko53f72bb2010-03-21 06:46:09 +0100558 || dhcp_pkt->ciaddr == 0
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100559 ) {
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200560 log1("broadcasting packet to client");
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100561 ciaddr = INADDR_BROADCAST;
562 chaddr = MAC_BCAST_ADDR;
563 } else {
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200564 log1("unicasting packet to client ciaddr");
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100565 ciaddr = dhcp_pkt->ciaddr;
566 chaddr = dhcp_pkt->chaddr;
567 }
568
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100569 udhcp_send_raw_packet(dhcp_pkt,
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100570 /*src*/ server_config.server_nip, SERVER_PORT,
571 /*dst*/ ciaddr, CLIENT_PORT, chaddr,
572 server_config.ifindex);
573}
574
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100575/* Send a packet to gateway_nip using the kernel ip stack */
576static void send_packet_to_relay(struct dhcp_packet *dhcp_pkt)
577{
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200578 log1("forwarding packet to relay");
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100579
580 udhcp_send_kernel_packet(dhcp_pkt,
581 server_config.server_nip, SERVER_PORT,
582 dhcp_pkt->gateway_nip, SERVER_PORT);
583}
584
585static void send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100586{
587 if (dhcp_pkt->gateway_nip)
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100588 send_packet_to_relay(dhcp_pkt);
589 else
590 send_packet_to_client(dhcp_pkt, force_broadcast);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100591}
592
593static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type)
594{
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100595 /* Sets op, htype, hlen, cookie fields
596 * and adds DHCP_MESSAGE_TYPE option */
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100597 udhcp_init_header(packet, type);
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100598
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100599 packet->xid = oldpacket->xid;
600 memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr));
601 packet->flags = oldpacket->flags;
602 packet->gateway_nip = oldpacket->gateway_nip;
603 packet->ciaddr = oldpacket->ciaddr;
Denys Vlasenko7724c762010-03-26 09:32:09 +0100604 udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_config.server_nip);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100605}
606
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100607/* Fill options field, siaddr_nip, and sname and boot_file fields.
608 * TODO: teach this code to use overload option.
609 */
610static void add_server_options(struct dhcp_packet *packet)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100611{
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100612 struct option_set *curr = server_config.options;
613
614 while (curr) {
615 if (curr->data[OPT_CODE] != DHCP_LEASE_TIME)
Denys Vlasenko7724c762010-03-26 09:32:09 +0100616 udhcp_add_binary_option(packet, curr->data);
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100617 curr = curr->next;
618 }
619
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100620 packet->siaddr_nip = server_config.siaddr_nip;
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100621
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100622 if (server_config.sname)
623 strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1);
624 if (server_config.boot_file)
625 strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1);
626}
627
628static uint32_t select_lease_time(struct dhcp_packet *packet)
629{
630 uint32_t lease_time_sec = server_config.max_lease_sec;
Denys Vlasenkodde8bdc2010-03-22 14:29:13 +0100631 uint8_t *lease_time_opt = udhcp_get_option(packet, DHCP_LEASE_TIME);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100632 if (lease_time_opt) {
633 move_from_unaligned32(lease_time_sec, lease_time_opt);
634 lease_time_sec = ntohl(lease_time_sec);
635 if (lease_time_sec > server_config.max_lease_sec)
636 lease_time_sec = server_config.max_lease_sec;
637 if (lease_time_sec < server_config.min_lease_sec)
638 lease_time_sec = server_config.min_lease_sec;
639 }
640 return lease_time_sec;
641}
642
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100643/* We got a DHCP DISCOVER. Send an OFFER. */
Denys Vlasenko0bb35e12010-10-21 12:33:10 +0200644/* NOINLINE: limit stack usage in caller */
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100645static NOINLINE void send_offer(struct dhcp_packet *oldpacket,
646 uint32_t static_lease_nip,
647 struct dyn_lease *lease,
Michel Stam9f412712014-10-30 11:59:04 +0100648 uint8_t *requested_ip_opt,
649 unsigned arpping_ms)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100650{
651 struct dhcp_packet packet;
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100652 uint32_t lease_time_sec;
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100653 struct in_addr addr;
654
655 init_packet(&packet, oldpacket, DHCPOFFER);
656
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100657 /* If it is a static lease, use its IP */
658 packet.yiaddr = static_lease_nip;
659 /* Else: */
Denys Vlasenkoa9539872010-03-20 03:49:27 +0100660 if (!static_lease_nip) {
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100661 /* We have no static lease for client's chaddr */
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100662 uint32_t req_nip;
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100663 const char *p_host_name;
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100664
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100665 if (lease) {
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100666 /* We have a dynamic lease for client's chaddr.
667 * Reuse its IP (even if lease is expired).
668 * Note that we ignore requested IP in this case.
669 */
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100670 packet.yiaddr = lease->lease_nip;
671 }
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100672 /* Or: if client has requested an IP */
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100673 else if (requested_ip_opt != NULL
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100674 /* (read IP) */
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100675 && (move_from_unaligned32(req_nip, requested_ip_opt), 1)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100676 /* and the IP is in the lease range */
677 && ntohl(req_nip) >= server_config.start_ip
678 && ntohl(req_nip) <= server_config.end_ip
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100679 /* and */
680 && ( !(lease = find_lease_by_nip(req_nip)) /* is not already taken */
681 || is_expired_lease(lease) /* or is taken, but expired */
682 )
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100683 ) {
684 packet.yiaddr = req_nip;
685 }
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100686 else {
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100687 /* Otherwise, find a free IP */
Michel Stam9f412712014-10-30 11:59:04 +0100688 packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr, arpping_ms);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100689 }
690
691 if (!packet.yiaddr) {
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100692 bb_error_msg("no free IP addresses. OFFER abandoned");
693 return;
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100694 }
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100695 /* Reserve the IP for a short time hoping to get DHCPREQUEST soon */
Denys Vlasenkodde8bdc2010-03-22 14:29:13 +0100696 p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100697 lease = add_lease(packet.chaddr, packet.yiaddr,
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100698 server_config.offer_time,
699 p_host_name,
700 p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100701 );
702 if (!lease) {
703 bb_error_msg("no free IP addresses. OFFER abandoned");
704 return;
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100705 }
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100706 }
707
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100708 lease_time_sec = select_lease_time(oldpacket);
Denys Vlasenko7724c762010-03-26 09:32:09 +0100709 udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100710 add_server_options(&packet);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100711
712 addr.s_addr = packet.yiaddr;
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200713 bb_error_msg("sending OFFER of %s", inet_ntoa(addr));
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100714 /* send_packet emits error message itself if it detects failure */
715 send_packet(&packet, /*force_bcast:*/ 0);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100716}
717
Denys Vlasenko0bb35e12010-10-21 12:33:10 +0200718/* NOINLINE: limit stack usage in caller */
719static NOINLINE void send_NAK(struct dhcp_packet *oldpacket)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100720{
721 struct dhcp_packet packet;
722
723 init_packet(&packet, oldpacket, DHCPNAK);
724
Denys Vlasenko16efe192016-03-30 18:44:52 +0200725 log1("sending %s", "NAK");
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100726 send_packet(&packet, /*force_bcast:*/ 1);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100727}
728
Denys Vlasenko0bb35e12010-10-21 12:33:10 +0200729/* NOINLINE: limit stack usage in caller */
730static NOINLINE void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100731{
732 struct dhcp_packet packet;
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100733 uint32_t lease_time_sec;
734 struct in_addr addr;
735 const char *p_host_name;
736
737 init_packet(&packet, oldpacket, DHCPACK);
738 packet.yiaddr = yiaddr;
739
740 lease_time_sec = select_lease_time(oldpacket);
Denys Vlasenko7724c762010-03-26 09:32:09 +0100741 udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec));
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100742
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100743 add_server_options(&packet);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100744
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100745 addr.s_addr = yiaddr;
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200746 bb_error_msg("sending ACK to %s", inet_ntoa(addr));
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100747 send_packet(&packet, /*force_bcast:*/ 0);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100748
Denys Vlasenkodde8bdc2010-03-22 14:29:13 +0100749 p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100750 add_lease(packet.chaddr, packet.yiaddr,
751 lease_time_sec,
752 p_host_name,
753 p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0
754 );
755 if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) {
756 /* rewrite the file with leases at every new acceptance */
757 write_leases();
758 }
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100759}
760
Denys Vlasenko0bb35e12010-10-21 12:33:10 +0200761/* NOINLINE: limit stack usage in caller */
762static NOINLINE void send_inform(struct dhcp_packet *oldpacket)
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100763{
764 struct dhcp_packet packet;
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100765
Denys Vlasenkof8fcc182010-04-04 22:36:34 +0200766 /* "If a client has obtained a network address through some other means
767 * (e.g., manual configuration), it may use a DHCPINFORM request message
768 * to obtain other local configuration parameters. Servers receiving a
769 * DHCPINFORM message construct a DHCPACK message with any local
770 * configuration parameters appropriate for the client without:
771 * allocating a new address, checking for an existing binding, filling
772 * in 'yiaddr' or including lease time parameters. The servers SHOULD
773 * unicast the DHCPACK reply to the address given in the 'ciaddr' field
774 * of the DHCPINFORM message.
775 * ...
776 * The server responds to a DHCPINFORM message by sending a DHCPACK
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100777 * message directly to the address given in the 'ciaddr' field
778 * of the DHCPINFORM message. The server MUST NOT send a lease
779 * expiration time to the client and SHOULD NOT fill in 'yiaddr'."
780 */
Denys Vlasenkof8fcc182010-04-04 22:36:34 +0200781//TODO: do a few sanity checks: is ciaddr set?
782//Better yet: is ciaddr == IP source addr?
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100783 init_packet(&packet, oldpacket, DHCPACK);
Denys Vlasenkoe5ce91b2010-03-21 00:43:11 +0100784 add_server_options(&packet);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100785
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100786 send_packet(&packet, /*force_bcast:*/ 0);
Denys Vlasenko8a7c1662010-03-20 03:48:11 +0100787}
788
Denis Vlasenko9b49a5e2007-10-11 10:05:36 +0000789int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
Denis Vlasenkoa60f84e2008-07-05 09:18:54 +0000790int udhcpd_main(int argc UNUSED_PARAM, char **argv)
Mike Frysinger7031f622006-05-08 03:20:50 +0000791{
Denis Vlasenko0416e3d2009-01-01 17:52:09 +0000792 int server_socket = -1, retval, max_sock;
Denys Vlasenko6947d2c2009-06-17 13:24:03 +0200793 uint8_t *state;
Denis Vlasenko42b3dea2007-07-03 15:47:50 +0000794 unsigned timeout_end;
795 unsigned num_ips;
Denis Vlasenko3d17d2b2007-08-14 16:45:29 +0000796 unsigned opt;
Mike Frysinger7031f622006-05-08 03:20:50 +0000797 struct option_set *option;
Denys Vlasenkoe3f5b732013-03-13 22:27:37 +0100798 char *str_I = str_I;
Michel Stam9f412712014-10-30 11:59:04 +0100799 const char *str_a = "2000";
800 unsigned arpping_ms;
Denis Vlasenko5e34ff22009-04-21 11:09:40 +0000801 IF_FEATURE_UDHCP_PORT(char *str_P;)
Mike Frysinger7031f622006-05-08 03:20:50 +0000802
Denys Vlasenkodf70a432016-04-21 18:54:36 +0200803 setup_common_bufsiz();
804
805 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
806 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
Denis Vlasenkod55fe3e2008-02-04 13:12:16 +0000807
Denys Vlasenkoac906fa2009-06-17 11:54:52 +0200808#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
809 opt_complementary = "vv";
810#endif
Michel Stam9f412712014-10-30 11:59:04 +0100811 opt = getopt32(argv, "fSI:va:"
Denys Vlasenkoe3f5b732013-03-13 22:27:37 +0100812 IF_FEATURE_UDHCP_PORT("P:")
813 , &str_I
Michel Stam9f412712014-10-30 11:59:04 +0100814 , &str_a
Denys Vlasenkoe3f5b732013-03-13 22:27:37 +0100815 IF_FEATURE_UDHCP_PORT(, &str_P)
Leonid Lisovskiy6c9c0a12011-10-18 00:35:47 +0200816 IF_UDHCP_VERBOSE(, &dhcp_verbose)
Denys Vlasenkoac906fa2009-06-17 11:54:52 +0200817 );
Denis Vlasenko3d17d2b2007-08-14 16:45:29 +0000818 if (!(opt & 1)) { /* no -f */
Denis Vlasenkoc82b5102007-07-01 17:05:57 +0000819 bb_daemonize_or_rexec(0, argv);
Denis Vlasenkoa19e6492009-03-11 14:40:00 +0000820 logmode = LOGMODE_NONE;
Denis Vlasenkoaf1c8432007-03-26 13:22:35 +0000821 }
Mike Frysinger6db13732010-06-04 13:24:50 -0400822 /* update argv after the possible vfork+exec in daemonize */
823 argv += optind;
Denis Vlasenko3d17d2b2007-08-14 16:45:29 +0000824 if (opt & 2) { /* -S */
Denis Vlasenko5e4fda02009-03-08 23:46:48 +0000825 openlog(applet_name, LOG_PID, LOG_DAEMON);
Denis Vlasenkoaf1c8432007-03-26 13:22:35 +0000826 logmode |= LOGMODE_SYSLOG;
827 }
Denys Vlasenkoe3f5b732013-03-13 22:27:37 +0100828 if (opt & 4) { /* -I */
829 len_and_sockaddr *lsa = xhost_and_af2sockaddr(str_I, 0, AF_INET);
830 server_config.server_nip = lsa->u.sin.sin_addr.s_addr;
831 free(lsa);
832 }
Denis Vlasenkod55fe3e2008-02-04 13:12:16 +0000833#if ENABLE_FEATURE_UDHCP_PORT
Michel Stam9f412712014-10-30 11:59:04 +0100834 if (opt & 32) { /* -P */
Denis Vlasenkod55fe3e2008-02-04 13:12:16 +0000835 SERVER_PORT = xatou16(str_P);
836 CLIENT_PORT = SERVER_PORT + 1;
837 }
838#endif
Michel Stam9f412712014-10-30 11:59:04 +0100839 arpping_ms = xatou(str_a);
840
Denis Vlasenkoaf1c8432007-03-26 13:22:35 +0000841 /* Would rather not do read_config before daemonization -
842 * otherwise NOMMU machines will parse config twice */
Denis Vlasenko9f7b92a2007-08-15 20:03:36 +0000843 read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE);
Mike Frysinger7031f622006-05-08 03:20:50 +0000844
Denis Vlasenko80edead2007-08-02 22:31:05 +0000845 /* Make sure fd 0,1,2 are open */
846 bb_sanitize_stdio();
847 /* Equivalent of doing a fflush after every \n */
848 setlinebuf(stdout);
849
850 /* Create pidfile */
851 write_pidfile(server_config.pidfile);
Denys Vlasenko6331cf02009-11-13 09:08:27 +0100852 /* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */
Denis Vlasenko80edead2007-08-02 22:31:05 +0000853
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200854 bb_error_msg("started, v"BB_VER);
Mike Frysinger7031f622006-05-08 03:20:50 +0000855
Denys Vlasenko7724c762010-03-26 09:32:09 +0100856 option = udhcp_find_option(server_config.options, DHCP_LEASE_TIME);
Denys Vlasenko2e7aa922010-03-21 02:22:07 +0100857 server_config.max_lease_sec = DEFAULT_LEASE_TIME;
Denis Vlasenkoaf1c8432007-03-26 13:22:35 +0000858 if (option) {
Denys Vlasenko6947d2c2009-06-17 13:24:03 +0200859 move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA);
860 server_config.max_lease_sec = ntohl(server_config.max_lease_sec);
Denis Vlasenko6e6d3312007-05-03 23:39:35 +0000861 }
Mike Frysinger7031f622006-05-08 03:20:50 +0000862
863 /* Sanity check */
Denis Vlasenkoc82b5102007-07-01 17:05:57 +0000864 num_ips = server_config.end_ip - server_config.start_ip + 1;
Mike Frysinger7031f622006-05-08 03:20:50 +0000865 if (server_config.max_leases > num_ips) {
Denis Vlasenko42b3dea2007-07-03 15:47:50 +0000866 bb_error_msg("max_leases=%u is too big, setting to %u",
867 (unsigned)server_config.max_leases, num_ips);
Mike Frysinger7031f622006-05-08 03:20:50 +0000868 server_config.max_leases = num_ips;
869 }
870
Denys Vlasenko6947d2c2009-06-17 13:24:03 +0200871 g_leases = xzalloc(server_config.max_leases * sizeof(g_leases[0]));
Mike Frysinger7031f622006-05-08 03:20:50 +0000872 read_leases(server_config.lease_file);
873
Denys Vlasenko26918dd2009-06-16 12:04:23 +0200874 if (udhcp_read_interface(server_config.interface,
875 &server_config.ifindex,
Denys Vlasenkoe3f5b732013-03-13 22:27:37 +0100876 (server_config.server_nip == 0 ? &server_config.server_nip : NULL),
Denys Vlasenko26918dd2009-06-16 12:04:23 +0200877 server_config.server_mac)
878 ) {
Denis Vlasenko6e6d3312007-05-03 23:39:35 +0000879 retval = 1;
880 goto ret;
881 }
Mike Frysinger7031f622006-05-08 03:20:50 +0000882
Mike Frysinger7031f622006-05-08 03:20:50 +0000883 /* Setup the signal pipe */
884 udhcp_sp_setup();
885
Denys Vlasenko71045cc2012-07-24 17:21:26 +0200886 continue_with_autotime:
Denis Vlasenko42b3dea2007-07-03 15:47:50 +0000887 timeout_end = monotonic_sec() + server_config.auto_time;
Denis Vlasenko5a3395b2006-11-18 19:51:32 +0000888 while (1) { /* loop until universe collapses */
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100889 fd_set rfds;
890 struct dhcp_packet packet;
Denis Vlasenko0416e3d2009-01-01 17:52:09 +0000891 int bytes;
892 struct timeval tv;
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100893 uint8_t *server_id_opt;
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100894 uint8_t *requested_ip_opt;
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100895 uint32_t requested_nip = requested_nip; /* for compiler */
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100896 uint32_t static_lease_nip;
897 struct dyn_lease *lease, fake_lease;
Mike Frysinger7031f622006-05-08 03:20:50 +0000898
Denis Vlasenkoe2d3ded2006-11-27 23:43:28 +0000899 if (server_socket < 0) {
Denis Vlasenkof1980f62008-09-26 09:34:59 +0000900 server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT,
Denis Vlasenko6e6d3312007-05-03 23:39:35 +0000901 server_config.interface);
Denis Vlasenkoe2d3ded2006-11-27 23:43:28 +0000902 }
Mike Frysinger7031f622006-05-08 03:20:50 +0000903
904 max_sock = udhcp_sp_fd_set(&rfds, server_socket);
905 if (server_config.auto_time) {
Denys Vlasenko936c4012015-01-27 21:59:40 +0100906 /* cast to signed is essential if tv_sec is wider than int */
907 tv.tv_sec = (int)(timeout_end - monotonic_sec());
Mike Frysinger7031f622006-05-08 03:20:50 +0000908 tv.tv_usec = 0;
909 }
Denis Vlasenko6e6d3312007-05-03 23:39:35 +0000910 retval = 0;
Mike Frysinger7031f622006-05-08 03:20:50 +0000911 if (!server_config.auto_time || tv.tv_sec > 0) {
912 retval = select(max_sock + 1, &rfds, NULL, NULL,
913 server_config.auto_time ? &tv : NULL);
Denis Vlasenko6e6d3312007-05-03 23:39:35 +0000914 }
Mike Frysinger7031f622006-05-08 03:20:50 +0000915 if (retval == 0) {
916 write_leases();
Denys Vlasenko71045cc2012-07-24 17:21:26 +0200917 goto continue_with_autotime;
Denis Vlasenko6e6d3312007-05-03 23:39:35 +0000918 }
919 if (retval < 0 && errno != EINTR) {
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200920 log1("error on select");
Mike Frysinger7031f622006-05-08 03:20:50 +0000921 continue;
922 }
923
924 switch (udhcp_sp_read(&rfds)) {
925 case SIGUSR1:
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200926 bb_error_msg("received %s", "SIGUSR1");
Mike Frysinger7031f622006-05-08 03:20:50 +0000927 write_leases();
928 /* why not just reset the timeout, eh */
Denys Vlasenko71045cc2012-07-24 17:21:26 +0200929 goto continue_with_autotime;
Mike Frysinger7031f622006-05-08 03:20:50 +0000930 case SIGTERM:
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200931 bb_error_msg("received %s", "SIGTERM");
Denys Vlasenko71045cc2012-07-24 17:21:26 +0200932 write_leases();
Denis Vlasenko6e6d3312007-05-03 23:39:35 +0000933 goto ret0;
Denys Vlasenkoe4dcba12010-10-28 18:57:19 +0200934 case 0: /* no signal: read a packet */
Denis Vlasenko0416e3d2009-01-01 17:52:09 +0000935 break;
936 default: /* signal or error (probably EINTR): back to select */
937 continue;
Mike Frysinger7031f622006-05-08 03:20:50 +0000938 }
939
Denis Vlasenko0416e3d2009-01-01 17:52:09 +0000940 bytes = udhcp_recv_kernel_packet(&packet, server_socket);
Denis Vlasenkoaf1c8432007-03-26 13:22:35 +0000941 if (bytes < 0) {
Denis Vlasenko0416e3d2009-01-01 17:52:09 +0000942 /* bytes can also be -2 ("bad packet data") */
Mike Frysinger7031f622006-05-08 03:20:50 +0000943 if (bytes == -1 && errno != EINTR) {
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200944 log1("read error: %s, reopening socket", strerror(errno));
Mike Frysinger7031f622006-05-08 03:20:50 +0000945 close(server_socket);
946 server_socket = -1;
947 }
948 continue;
949 }
Denys Vlasenko31af3d52009-06-17 11:57:09 +0200950 if (packet.hlen != 6) {
951 bb_error_msg("MAC length != 6, ignoring packet");
952 continue;
953 }
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100954 if (packet.op != BOOTREQUEST) {
955 bb_error_msg("not a REQUEST, ignoring packet");
956 continue;
957 }
Denys Vlasenkodde8bdc2010-03-22 14:29:13 +0100958 state = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100959 if (state == NULL || state[0] < DHCP_MINTYPE || state[0] > DHCP_MAXTYPE) {
960 bb_error_msg("no or bad message type option, ignoring packet");
Mike Frysinger7031f622006-05-08 03:20:50 +0000961 continue;
962 }
963
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100964 /* Get SERVER_ID if present */
965 server_id_opt = udhcp_get_option(&packet, DHCP_SERVER_ID);
966 if (server_id_opt) {
Denys Vlasenko713d2412010-11-28 21:51:44 +0100967 uint32_t server_id_network_order;
968 move_from_unaligned32(server_id_network_order, server_id_opt);
969 if (server_id_network_order != server_config.server_nip) {
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100970 /* client talks to somebody else */
971 log1("server ID doesn't match, ignoring");
972 continue;
973 }
974 }
975
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100976 /* Look for a static/dynamic lease */
Denys Vlasenkoa9539872010-03-20 03:49:27 +0100977 static_lease_nip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr);
978 if (static_lease_nip) {
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200979 bb_error_msg("found static lease: %x", static_lease_nip);
Denys Vlasenko6947d2c2009-06-17 13:24:03 +0200980 memcpy(&fake_lease.lease_mac, &packet.chaddr, 6);
Denys Vlasenkoa9539872010-03-20 03:49:27 +0100981 fake_lease.lease_nip = static_lease_nip;
Denys Vlasenko6947d2c2009-06-17 13:24:03 +0200982 fake_lease.expires = 0;
Denys Vlasenko6947d2c2009-06-17 13:24:03 +0200983 lease = &fake_lease;
Denis Vlasenko5a3395b2006-11-18 19:51:32 +0000984 } else {
Denys Vlasenko6947d2c2009-06-17 13:24:03 +0200985 lease = find_lease_by_mac(packet.chaddr);
Mike Frysinger7031f622006-05-08 03:20:50 +0000986 }
987
Denys Vlasenkofa5e2952010-11-28 01:10:51 +0100988 /* Get REQUESTED_IP if present */
989 requested_ip_opt = udhcp_get_option(&packet, DHCP_REQUESTED_IP);
990 if (requested_ip_opt) {
991 move_from_unaligned32(requested_nip, requested_ip_opt);
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100992 }
993
Mike Frysinger7031f622006-05-08 03:20:50 +0000994 switch (state[0]) {
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +0100995
Mike Frysinger7031f622006-05-08 03:20:50 +0000996 case DHCPDISCOVER:
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +0200997 log1("received %s", "DISCOVER");
Mike Frysinger7031f622006-05-08 03:20:50 +0000998
Michel Stam9f412712014-10-30 11:59:04 +0100999 send_offer(&packet, static_lease_nip, lease, requested_ip_opt, arpping_ms);
Mike Frysinger7031f622006-05-08 03:20:50 +00001000 break;
Denys Vlasenko6947d2c2009-06-17 13:24:03 +02001001
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001002 case DHCPREQUEST:
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +02001003 log1("received %s", "REQUEST");
Denys Vlasenko53f72bb2010-03-21 06:46:09 +01001004/* RFC 2131:
Mike Frysinger7031f622006-05-08 03:20:50 +00001005
Denys Vlasenko53f72bb2010-03-21 06:46:09 +01001006o DHCPREQUEST generated during SELECTING state:
1007
1008 Client inserts the address of the selected server in 'server
1009 identifier', 'ciaddr' MUST be zero, 'requested IP address' MUST be
1010 filled in with the yiaddr value from the chosen DHCPOFFER.
1011
1012 Note that the client may choose to collect several DHCPOFFER
1013 messages and select the "best" offer. The client indicates its
1014 selection by identifying the offering server in the DHCPREQUEST
1015 message. If the client receives no acceptable offers, the client
1016 may choose to try another DHCPDISCOVER message. Therefore, the
1017 servers may not receive a specific DHCPREQUEST from which they can
1018 decide whether or not the client has accepted the offer.
1019
1020o DHCPREQUEST generated during INIT-REBOOT state:
1021
1022 'server identifier' MUST NOT be filled in, 'requested IP address'
1023 option MUST be filled in with client's notion of its previously
1024 assigned address. 'ciaddr' MUST be zero. The client is seeking to
1025 verify a previously allocated, cached configuration. Server SHOULD
1026 send a DHCPNAK message to the client if the 'requested IP address'
1027 is incorrect, or is on the wrong network.
1028
1029 Determining whether a client in the INIT-REBOOT state is on the
1030 correct network is done by examining the contents of 'giaddr', the
1031 'requested IP address' option, and a database lookup. If the DHCP
1032 server detects that the client is on the wrong net (i.e., the
1033 result of applying the local subnet mask or remote subnet mask (if
1034 'giaddr' is not zero) to 'requested IP address' option value
1035 doesn't match reality), then the server SHOULD send a DHCPNAK
1036 message to the client.
1037
1038 If the network is correct, then the DHCP server should check if
1039 the client's notion of its IP address is correct. If not, then the
1040 server SHOULD send a DHCPNAK message to the client. If the DHCP
1041 server has no record of this client, then it MUST remain silent,
1042 and MAY output a warning to the network administrator. This
1043 behavior is necessary for peaceful coexistence of non-
1044 communicating DHCP servers on the same wire.
1045
1046 If 'giaddr' is 0x0 in the DHCPREQUEST message, the client is on
1047 the same subnet as the server. The server MUST broadcast the
1048 DHCPNAK message to the 0xffffffff broadcast address because the
1049 client may not have a correct network address or subnet mask, and
1050 the client may not be answering ARP requests.
1051
1052 If 'giaddr' is set in the DHCPREQUEST message, the client is on a
1053 different subnet. The server MUST set the broadcast bit in the
1054 DHCPNAK, so that the relay agent will broadcast the DHCPNAK to the
1055 client, because the client may not have a correct network address
1056 or subnet mask, and the client may not be answering ARP requests.
1057
1058o DHCPREQUEST generated during RENEWING state:
1059
1060 'server identifier' MUST NOT be filled in, 'requested IP address'
1061 option MUST NOT be filled in, 'ciaddr' MUST be filled in with
1062 client's IP address. In this situation, the client is completely
1063 configured, and is trying to extend its lease. This message will
1064 be unicast, so no relay agents will be involved in its
1065 transmission. Because 'giaddr' is therefore not filled in, the
1066 DHCP server will trust the value in 'ciaddr', and use it when
1067 replying to the client.
1068
1069 A client MAY choose to renew or extend its lease prior to T1. The
1070 server may choose not to extend the lease (as a policy decision by
1071 the network administrator), but should return a DHCPACK message
1072 regardless.
1073
1074o DHCPREQUEST generated during REBINDING state:
1075
1076 'server identifier' MUST NOT be filled in, 'requested IP address'
1077 option MUST NOT be filled in, 'ciaddr' MUST be filled in with
1078 client's IP address. In this situation, the client is completely
1079 configured, and is trying to extend its lease. This message MUST
1080 be broadcast to the 0xffffffff IP broadcast address. The DHCP
1081 server SHOULD check 'ciaddr' for correctness before replying to
1082 the DHCPREQUEST.
1083
1084 The DHCPREQUEST from a REBINDING client is intended to accommodate
1085 sites that have multiple DHCP servers and a mechanism for
1086 maintaining consistency among leases managed by multiple servers.
1087 A DHCP server MAY extend a client's lease only if it has local
1088 administrative authority to do so.
1089*/
Denys Vlasenkofa5e2952010-11-28 01:10:51 +01001090 if (!requested_ip_opt) {
Denys Vlasenko53f72bb2010-03-21 06:46:09 +01001091 requested_nip = packet.ciaddr;
1092 if (requested_nip == 0) {
1093 log1("no requested IP and no ciaddr, ignoring");
1094 break;
1095 }
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001096 }
1097 if (lease && requested_nip == lease->lease_nip) {
Denys Vlasenko53f72bb2010-03-21 06:46:09 +01001098 /* client requested or configured IP matches the lease.
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001099 * ACK it, and bump lease expiration time. */
1100 send_ACK(&packet, lease->lease_nip);
1101 break;
1102 }
Denys Vlasenko713d2412010-11-28 21:51:44 +01001103 /* No lease for this MAC, or lease IP != requested IP */
1104
1105 if (server_id_opt /* client is in SELECTING state */
1106 || requested_ip_opt /* client is in INIT-REBOOT state */
1107 ) {
1108 /* "No, we don't have this IP for you" */
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001109 send_NAK(&packet);
Denys Vlasenko713d2412010-11-28 21:51:44 +01001110 } /* else: client is in RENEWING or REBINDING, do not answer */
1111
Mike Frysinger7031f622006-05-08 03:20:50 +00001112 break;
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001113
Mike Frysinger7031f622006-05-08 03:20:50 +00001114 case DHCPDECLINE:
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001115 /* RFC 2131:
1116 * "If the server receives a DHCPDECLINE message,
1117 * the client has discovered through some other means
1118 * that the suggested network address is already
1119 * in use. The server MUST mark the network address
1120 * as not available and SHOULD notify the local
1121 * sysadmin of a possible configuration problem."
1122 *
1123 * SERVER_ID must be present,
1124 * REQUESTED_IP must be present,
1125 * chaddr must be filled in,
1126 * ciaddr must be 0 (we do not check this)
1127 */
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +02001128 log1("received %s", "DECLINE");
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001129 if (server_id_opt
Denys Vlasenkofa5e2952010-11-28 01:10:51 +01001130 && requested_ip_opt
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001131 && lease /* chaddr matches this lease */
1132 && requested_nip == lease->lease_nip
1133 ) {
Denys Vlasenko31af3d52009-06-17 11:57:09 +02001134 memset(lease->lease_mac, 0, sizeof(lease->lease_mac));
Denis Vlasenko04158e02009-02-02 10:48:06 +00001135 lease->expires = time(NULL) + server_config.decline_time;
Mike Frysinger7031f622006-05-08 03:20:50 +00001136 }
1137 break;
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001138
Mike Frysinger7031f622006-05-08 03:20:50 +00001139 case DHCPRELEASE:
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001140 /* "Upon receipt of a DHCPRELEASE message, the server
1141 * marks the network address as not allocated."
1142 *
1143 * SERVER_ID must be present,
1144 * REQUESTED_IP must not be present (we do not check this),
1145 * chaddr must be filled in,
1146 * ciaddr must be filled in
1147 */
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +02001148 log1("received %s", "RELEASE");
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001149 if (server_id_opt
1150 && lease /* chaddr matches this lease */
1151 && packet.ciaddr == lease->lease_nip
1152 ) {
Denis Vlasenko04158e02009-02-02 10:48:06 +00001153 lease->expires = time(NULL);
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001154 }
Mike Frysinger7031f622006-05-08 03:20:50 +00001155 break;
Denys Vlasenkoc7dc79e2010-03-21 06:15:28 +01001156
Mike Frysinger7031f622006-05-08 03:20:50 +00001157 case DHCPINFORM:
Denys Vlasenko8f2e99c2016-03-30 18:41:23 +02001158 log1("received %s", "INFORM");
Mike Frysinger7031f622006-05-08 03:20:50 +00001159 send_inform(&packet);
1160 break;
Mike Frysinger7031f622006-05-08 03:20:50 +00001161 }
1162 }
Denis Vlasenko6e6d3312007-05-03 23:39:35 +00001163 ret0:
1164 retval = 0;
1165 ret:
Denis Vlasenko42b3dea2007-07-03 15:47:50 +00001166 /*if (server_config.pidfile) - server_config.pidfile is never NULL */
Denis Vlasenko6e6d3312007-05-03 23:39:35 +00001167 remove_pidfile(server_config.pidfile);
1168 return retval;
Mike Frysinger7031f622006-05-08 03:20:50 +00001169}