Annotation of /trunk/mkinitrd-magellan/busybox/networking/udhcp/dhcpd.c
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Revision 1123 -
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Wed Aug 18 21:56:57 2010 UTC (13 years, 9 months ago) by niro
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Wed Aug 18 21:56:57 2010 UTC (13 years, 9 months ago) by niro
File MIME type: text/plain
File size: 21088 byte(s)
-updated to busybox-1.17.1
1 | niro | 532 | /* vi: set sw=4 ts=4: */ |
2 | niro | 1123 | /* |
3 | * udhcp server | ||
4 | niro | 532 | * 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 | * | ||
9 | niro | 1123 | * 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. | ||
22 | niro | 532 | */ |
23 | niro | 816 | #include <syslog.h> |
24 | niro | 532 | #include "common.h" |
25 | niro | 816 | #include "dhcpc.h" |
26 | niro | 532 | #include "dhcpd.h" |
27 | |||
28 | |||
29 | niro | 1123 | /* Send a packet to a specific mac address and ip address by creating our own ip packet */ |
30 | static void send_packet_to_client(struct dhcp_packet *dhcp_pkt, int force_broadcast) | ||
31 | { | ||
32 | const uint8_t *chaddr; | ||
33 | uint32_t ciaddr; | ||
34 | |||
35 | // Was: | ||
36 | //if (force_broadcast) { /* broadcast */ } | ||
37 | //else if (dhcp_pkt->ciaddr) { /* unicast to dhcp_pkt->ciaddr */ } | ||
38 | //else if (dhcp_pkt->flags & htons(BROADCAST_FLAG)) { /* broadcast */ } | ||
39 | //else { /* unicast to dhcp_pkt->yiaddr */ } | ||
40 | // But this is wrong: yiaddr is _our_ idea what client's IP is | ||
41 | // (for example, from lease file). Client may not know that, | ||
42 | // and may not have UDP socket listening on that IP! | ||
43 | // We should never unicast to dhcp_pkt->yiaddr! | ||
44 | // dhcp_pkt->ciaddr, OTOH, comes from client's request packet, | ||
45 | // and can be used. | ||
46 | |||
47 | if (force_broadcast | ||
48 | || (dhcp_pkt->flags & htons(BROADCAST_FLAG)) | ||
49 | || dhcp_pkt->ciaddr == 0 | ||
50 | ) { | ||
51 | log1("Broadcasting packet to client"); | ||
52 | ciaddr = INADDR_BROADCAST; | ||
53 | chaddr = MAC_BCAST_ADDR; | ||
54 | } else { | ||
55 | log1("Unicasting packet to client ciaddr"); | ||
56 | ciaddr = dhcp_pkt->ciaddr; | ||
57 | chaddr = dhcp_pkt->chaddr; | ||
58 | } | ||
59 | |||
60 | udhcp_send_raw_packet(dhcp_pkt, | ||
61 | /*src*/ server_config.server_nip, SERVER_PORT, | ||
62 | /*dst*/ ciaddr, CLIENT_PORT, chaddr, | ||
63 | server_config.ifindex); | ||
64 | } | ||
65 | |||
66 | /* Send a packet to gateway_nip using the kernel ip stack */ | ||
67 | static void send_packet_to_relay(struct dhcp_packet *dhcp_pkt) | ||
68 | { | ||
69 | log1("Forwarding packet to relay"); | ||
70 | |||
71 | udhcp_send_kernel_packet(dhcp_pkt, | ||
72 | server_config.server_nip, SERVER_PORT, | ||
73 | dhcp_pkt->gateway_nip, SERVER_PORT); | ||
74 | } | ||
75 | |||
76 | static void send_packet(struct dhcp_packet *dhcp_pkt, int force_broadcast) | ||
77 | { | ||
78 | if (dhcp_pkt->gateway_nip) | ||
79 | send_packet_to_relay(dhcp_pkt); | ||
80 | else | ||
81 | send_packet_to_client(dhcp_pkt, force_broadcast); | ||
82 | } | ||
83 | |||
84 | static void init_packet(struct dhcp_packet *packet, struct dhcp_packet *oldpacket, char type) | ||
85 | { | ||
86 | /* Sets op, htype, hlen, cookie fields | ||
87 | * and adds DHCP_MESSAGE_TYPE option */ | ||
88 | udhcp_init_header(packet, type); | ||
89 | |||
90 | packet->xid = oldpacket->xid; | ||
91 | memcpy(packet->chaddr, oldpacket->chaddr, sizeof(oldpacket->chaddr)); | ||
92 | packet->flags = oldpacket->flags; | ||
93 | packet->gateway_nip = oldpacket->gateway_nip; | ||
94 | packet->ciaddr = oldpacket->ciaddr; | ||
95 | udhcp_add_simple_option(packet, DHCP_SERVER_ID, server_config.server_nip); | ||
96 | } | ||
97 | |||
98 | /* Fill options field, siaddr_nip, and sname and boot_file fields. | ||
99 | * TODO: teach this code to use overload option. | ||
100 | */ | ||
101 | static void add_server_options(struct dhcp_packet *packet) | ||
102 | { | ||
103 | struct option_set *curr = server_config.options; | ||
104 | |||
105 | while (curr) { | ||
106 | if (curr->data[OPT_CODE] != DHCP_LEASE_TIME) | ||
107 | udhcp_add_binary_option(packet, curr->data); | ||
108 | curr = curr->next; | ||
109 | } | ||
110 | |||
111 | packet->siaddr_nip = server_config.siaddr_nip; | ||
112 | |||
113 | if (server_config.sname) | ||
114 | strncpy((char*)packet->sname, server_config.sname, sizeof(packet->sname) - 1); | ||
115 | if (server_config.boot_file) | ||
116 | strncpy((char*)packet->file, server_config.boot_file, sizeof(packet->file) - 1); | ||
117 | } | ||
118 | |||
119 | static uint32_t select_lease_time(struct dhcp_packet *packet) | ||
120 | { | ||
121 | uint32_t lease_time_sec = server_config.max_lease_sec; | ||
122 | uint8_t *lease_time_opt = udhcp_get_option(packet, DHCP_LEASE_TIME); | ||
123 | if (lease_time_opt) { | ||
124 | move_from_unaligned32(lease_time_sec, lease_time_opt); | ||
125 | lease_time_sec = ntohl(lease_time_sec); | ||
126 | if (lease_time_sec > server_config.max_lease_sec) | ||
127 | lease_time_sec = server_config.max_lease_sec; | ||
128 | if (lease_time_sec < server_config.min_lease_sec) | ||
129 | lease_time_sec = server_config.min_lease_sec; | ||
130 | } | ||
131 | return lease_time_sec; | ||
132 | } | ||
133 | |||
134 | /* We got a DHCP DISCOVER. Send an OFFER. */ | ||
135 | static void send_offer(struct dhcp_packet *oldpacket, uint32_t static_lease_nip, struct dyn_lease *lease) | ||
136 | { | ||
137 | struct dhcp_packet packet; | ||
138 | uint32_t lease_time_sec; | ||
139 | struct in_addr addr; | ||
140 | |||
141 | init_packet(&packet, oldpacket, DHCPOFFER); | ||
142 | |||
143 | /* If it is a static lease, use its IP */ | ||
144 | packet.yiaddr = static_lease_nip; | ||
145 | /* Else: */ | ||
146 | if (!static_lease_nip) { | ||
147 | /* We have no static lease for client's chaddr */ | ||
148 | uint32_t req_nip; | ||
149 | uint8_t *req_ip_opt; | ||
150 | const char *p_host_name; | ||
151 | |||
152 | if (lease) { | ||
153 | /* We have a dynamic lease for client's chaddr. | ||
154 | * Reuse its IP (even if lease is expired). | ||
155 | * Note that we ignore requested IP in this case. | ||
156 | */ | ||
157 | packet.yiaddr = lease->lease_nip; | ||
158 | } | ||
159 | /* Or: if client has requested an IP */ | ||
160 | else if ((req_ip_opt = udhcp_get_option(oldpacket, DHCP_REQUESTED_IP)) != NULL | ||
161 | /* (read IP) */ | ||
162 | && (move_from_unaligned32(req_nip, req_ip_opt), 1) | ||
163 | /* and the IP is in the lease range */ | ||
164 | && ntohl(req_nip) >= server_config.start_ip | ||
165 | && ntohl(req_nip) <= server_config.end_ip | ||
166 | /* and */ | ||
167 | && ( !(lease = find_lease_by_nip(req_nip)) /* is not already taken */ | ||
168 | || is_expired_lease(lease) /* or is taken, but expired */ | ||
169 | ) | ||
170 | ) { | ||
171 | packet.yiaddr = req_nip; | ||
172 | } | ||
173 | else { | ||
174 | /* Otherwise, find a free IP */ | ||
175 | packet.yiaddr = find_free_or_expired_nip(oldpacket->chaddr); | ||
176 | } | ||
177 | |||
178 | if (!packet.yiaddr) { | ||
179 | bb_error_msg("no free IP addresses. OFFER abandoned"); | ||
180 | return; | ||
181 | } | ||
182 | /* Reserve the IP for a short time hoping to get DHCPREQUEST soon */ | ||
183 | p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME); | ||
184 | lease = add_lease(packet.chaddr, packet.yiaddr, | ||
185 | server_config.offer_time, | ||
186 | p_host_name, | ||
187 | p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0 | ||
188 | ); | ||
189 | if (!lease) { | ||
190 | bb_error_msg("no free IP addresses. OFFER abandoned"); | ||
191 | return; | ||
192 | } | ||
193 | } | ||
194 | |||
195 | lease_time_sec = select_lease_time(oldpacket); | ||
196 | udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec)); | ||
197 | add_server_options(&packet); | ||
198 | |||
199 | addr.s_addr = packet.yiaddr; | ||
200 | bb_info_msg("Sending OFFER of %s", inet_ntoa(addr)); | ||
201 | /* send_packet emits error message itself if it detects failure */ | ||
202 | send_packet(&packet, /*force_bcast:*/ 0); | ||
203 | } | ||
204 | |||
205 | static void send_NAK(struct dhcp_packet *oldpacket) | ||
206 | { | ||
207 | struct dhcp_packet packet; | ||
208 | |||
209 | init_packet(&packet, oldpacket, DHCPNAK); | ||
210 | |||
211 | log1("Sending NAK"); | ||
212 | send_packet(&packet, /*force_bcast:*/ 1); | ||
213 | } | ||
214 | |||
215 | static void send_ACK(struct dhcp_packet *oldpacket, uint32_t yiaddr) | ||
216 | { | ||
217 | struct dhcp_packet packet; | ||
218 | uint32_t lease_time_sec; | ||
219 | struct in_addr addr; | ||
220 | const char *p_host_name; | ||
221 | |||
222 | init_packet(&packet, oldpacket, DHCPACK); | ||
223 | packet.yiaddr = yiaddr; | ||
224 | |||
225 | lease_time_sec = select_lease_time(oldpacket); | ||
226 | udhcp_add_simple_option(&packet, DHCP_LEASE_TIME, htonl(lease_time_sec)); | ||
227 | |||
228 | add_server_options(&packet); | ||
229 | |||
230 | addr.s_addr = yiaddr; | ||
231 | bb_info_msg("Sending ACK to %s", inet_ntoa(addr)); | ||
232 | send_packet(&packet, /*force_bcast:*/ 0); | ||
233 | |||
234 | p_host_name = (const char*) udhcp_get_option(oldpacket, DHCP_HOST_NAME); | ||
235 | add_lease(packet.chaddr, packet.yiaddr, | ||
236 | lease_time_sec, | ||
237 | p_host_name, | ||
238 | p_host_name ? (unsigned char)p_host_name[OPT_LEN - OPT_DATA] : 0 | ||
239 | ); | ||
240 | if (ENABLE_FEATURE_UDHCPD_WRITE_LEASES_EARLY) { | ||
241 | /* rewrite the file with leases at every new acceptance */ | ||
242 | write_leases(); | ||
243 | } | ||
244 | } | ||
245 | |||
246 | static void send_inform(struct dhcp_packet *oldpacket) | ||
247 | { | ||
248 | struct dhcp_packet packet; | ||
249 | |||
250 | /* "If a client has obtained a network address through some other means | ||
251 | * (e.g., manual configuration), it may use a DHCPINFORM request message | ||
252 | * to obtain other local configuration parameters. Servers receiving a | ||
253 | * DHCPINFORM message construct a DHCPACK message with any local | ||
254 | * configuration parameters appropriate for the client without: | ||
255 | * allocating a new address, checking for an existing binding, filling | ||
256 | * in 'yiaddr' or including lease time parameters. The servers SHOULD | ||
257 | * unicast the DHCPACK reply to the address given in the 'ciaddr' field | ||
258 | * of the DHCPINFORM message. | ||
259 | * ... | ||
260 | * The server responds to a DHCPINFORM message by sending a DHCPACK | ||
261 | * message directly to the address given in the 'ciaddr' field | ||
262 | * of the DHCPINFORM message. The server MUST NOT send a lease | ||
263 | * expiration time to the client and SHOULD NOT fill in 'yiaddr'." | ||
264 | */ | ||
265 | //TODO: do a few sanity checks: is ciaddr set? | ||
266 | //Better yet: is ciaddr == IP source addr? | ||
267 | init_packet(&packet, oldpacket, DHCPACK); | ||
268 | add_server_options(&packet); | ||
269 | |||
270 | send_packet(&packet, /*force_bcast:*/ 0); | ||
271 | } | ||
272 | |||
273 | |||
274 | niro | 532 | /* globals */ |
275 | niro | 984 | struct dyn_lease *g_leases; |
276 | niro | 816 | /* struct server_config_t server_config is in bb_common_bufsiz1 */ |
277 | niro | 532 | |
278 | |||
279 | niro | 816 | int udhcpd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
280 | int udhcpd_main(int argc UNUSED_PARAM, char **argv) | ||
281 | niro | 532 | { |
282 | fd_set rfds; | ||
283 | niro | 984 | int server_socket = -1, retval, max_sock; |
284 | struct dhcp_packet packet; | ||
285 | uint8_t *state; | ||
286 | niro | 1123 | uint32_t static_lease_nip; |
287 | niro | 816 | unsigned timeout_end; |
288 | unsigned num_ips; | ||
289 | unsigned opt; | ||
290 | niro | 532 | struct option_set *option; |
291 | niro | 984 | struct dyn_lease *lease, fake_lease; |
292 | IF_FEATURE_UDHCP_PORT(char *str_P;) | ||
293 | niro | 532 | |
294 | niro | 816 | #if ENABLE_FEATURE_UDHCP_PORT |
295 | SERVER_PORT = 67; | ||
296 | CLIENT_PORT = 68; | ||
297 | #endif | ||
298 | niro | 532 | |
299 | niro | 984 | #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1 |
300 | opt_complementary = "vv"; | ||
301 | #endif | ||
302 | opt = getopt32(argv, "fSv" | ||
303 | IF_FEATURE_UDHCP_PORT("P:", &str_P) | ||
304 | #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1 | ||
305 | , &dhcp_verbose | ||
306 | #endif | ||
307 | ); | ||
308 | niro | 816 | if (!(opt & 1)) { /* no -f */ |
309 | bb_daemonize_or_rexec(0, argv); | ||
310 | niro | 984 | logmode = LOGMODE_NONE; |
311 | niro | 816 | } |
312 | niro | 1123 | /* update argv after the possible vfork+exec in daemonize */ |
313 | argv += optind; | ||
314 | niro | 816 | if (opt & 2) { /* -S */ |
315 | niro | 984 | openlog(applet_name, LOG_PID, LOG_DAEMON); |
316 | niro | 816 | logmode |= LOGMODE_SYSLOG; |
317 | } | ||
318 | #if ENABLE_FEATURE_UDHCP_PORT | ||
319 | niro | 984 | if (opt & 8) { /* -P */ |
320 | niro | 816 | SERVER_PORT = xatou16(str_P); |
321 | CLIENT_PORT = SERVER_PORT + 1; | ||
322 | } | ||
323 | #endif | ||
324 | /* Would rather not do read_config before daemonization - | ||
325 | * otherwise NOMMU machines will parse config twice */ | ||
326 | read_config(argv[0] ? argv[0] : DHCPD_CONF_FILE); | ||
327 | |||
328 | /* Make sure fd 0,1,2 are open */ | ||
329 | bb_sanitize_stdio(); | ||
330 | /* Equivalent of doing a fflush after every \n */ | ||
331 | setlinebuf(stdout); | ||
332 | |||
333 | /* Create pidfile */ | ||
334 | write_pidfile(server_config.pidfile); | ||
335 | niro | 984 | /* if (!..) bb_perror_msg("can't create pidfile %s", pidfile); */ |
336 | niro | 816 | |
337 | bb_info_msg("%s (v"BB_VER") started", applet_name); | ||
338 | |||
339 | niro | 1123 | option = udhcp_find_option(server_config.options, DHCP_LEASE_TIME); |
340 | server_config.max_lease_sec = DEFAULT_LEASE_TIME; | ||
341 | niro | 816 | if (option) { |
342 | niro | 984 | move_from_unaligned32(server_config.max_lease_sec, option->data + OPT_DATA); |
343 | server_config.max_lease_sec = ntohl(server_config.max_lease_sec); | ||
344 | niro | 532 | } |
345 | |||
346 | /* Sanity check */ | ||
347 | niro | 816 | num_ips = server_config.end_ip - server_config.start_ip + 1; |
348 | niro | 532 | if (server_config.max_leases > num_ips) { |
349 | niro | 816 | bb_error_msg("max_leases=%u is too big, setting to %u", |
350 | (unsigned)server_config.max_leases, num_ips); | ||
351 | niro | 532 | server_config.max_leases = num_ips; |
352 | } | ||
353 | |||
354 | niro | 984 | g_leases = xzalloc(server_config.max_leases * sizeof(g_leases[0])); |
355 | niro | 532 | read_leases(server_config.lease_file); |
356 | |||
357 | niro | 984 | if (udhcp_read_interface(server_config.interface, |
358 | &server_config.ifindex, | ||
359 | &server_config.server_nip, | ||
360 | server_config.server_mac) | ||
361 | ) { | ||
362 | niro | 816 | retval = 1; |
363 | goto ret; | ||
364 | } | ||
365 | niro | 532 | |
366 | /* Setup the signal pipe */ | ||
367 | udhcp_sp_setup(); | ||
368 | |||
369 | niro | 816 | timeout_end = monotonic_sec() + server_config.auto_time; |
370 | niro | 532 | while (1) { /* loop until universe collapses */ |
371 | niro | 984 | int bytes; |
372 | struct timeval tv; | ||
373 | niro | 1123 | uint8_t *server_id_opt; |
374 | uint8_t *requested_opt; | ||
375 | uint32_t requested_nip = requested_nip; /* for compiler */ | ||
376 | niro | 532 | |
377 | if (server_socket < 0) { | ||
378 | niro | 816 | server_socket = udhcp_listen_socket(/*INADDR_ANY,*/ SERVER_PORT, |
379 | server_config.interface); | ||
380 | niro | 532 | } |
381 | |||
382 | max_sock = udhcp_sp_fd_set(&rfds, server_socket); | ||
383 | if (server_config.auto_time) { | ||
384 | niro | 816 | tv.tv_sec = timeout_end - monotonic_sec(); |
385 | niro | 532 | tv.tv_usec = 0; |
386 | } | ||
387 | niro | 816 | retval = 0; |
388 | niro | 532 | if (!server_config.auto_time || tv.tv_sec > 0) { |
389 | retval = select(max_sock + 1, &rfds, NULL, NULL, | ||
390 | server_config.auto_time ? &tv : NULL); | ||
391 | niro | 816 | } |
392 | niro | 532 | if (retval == 0) { |
393 | write_leases(); | ||
394 | niro | 816 | timeout_end = monotonic_sec() + server_config.auto_time; |
395 | niro | 532 | continue; |
396 | niro | 816 | } |
397 | if (retval < 0 && errno != EINTR) { | ||
398 | niro | 984 | log1("Error on select"); |
399 | niro | 532 | continue; |
400 | } | ||
401 | |||
402 | switch (udhcp_sp_read(&rfds)) { | ||
403 | case SIGUSR1: | ||
404 | niro | 1123 | bb_info_msg("Received SIGUSR1"); |
405 | niro | 532 | write_leases(); |
406 | /* why not just reset the timeout, eh */ | ||
407 | niro | 816 | timeout_end = monotonic_sec() + server_config.auto_time; |
408 | niro | 532 | continue; |
409 | case SIGTERM: | ||
410 | niro | 1123 | bb_info_msg("Received SIGTERM"); |
411 | niro | 816 | goto ret0; |
412 | niro | 984 | case 0: /* no signal: read a packet */ |
413 | break; | ||
414 | default: /* signal or error (probably EINTR): back to select */ | ||
415 | continue; | ||
416 | niro | 532 | } |
417 | |||
418 | niro | 984 | bytes = udhcp_recv_kernel_packet(&packet, server_socket); |
419 | niro | 816 | if (bytes < 0) { |
420 | niro | 984 | /* bytes can also be -2 ("bad packet data") */ |
421 | niro | 532 | if (bytes == -1 && errno != EINTR) { |
422 | niro | 984 | log1("Read error: %s, reopening socket", strerror(errno)); |
423 | niro | 532 | close(server_socket); |
424 | server_socket = -1; | ||
425 | } | ||
426 | continue; | ||
427 | } | ||
428 | niro | 984 | if (packet.hlen != 6) { |
429 | bb_error_msg("MAC length != 6, ignoring packet"); | ||
430 | continue; | ||
431 | } | ||
432 | niro | 1123 | if (packet.op != BOOTREQUEST) { |
433 | bb_error_msg("not a REQUEST, ignoring packet"); | ||
434 | niro | 532 | continue; |
435 | } | ||
436 | niro | 1123 | state = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE); |
437 | if (state == NULL || state[0] < DHCP_MINTYPE || state[0] > DHCP_MAXTYPE) { | ||
438 | bb_error_msg("no or bad message type option, ignoring packet"); | ||
439 | continue; | ||
440 | } | ||
441 | niro | 532 | |
442 | niro | 1123 | /* Look for a static/dynamic lease */ |
443 | static_lease_nip = get_static_nip_by_mac(server_config.static_leases, &packet.chaddr); | ||
444 | if (static_lease_nip) { | ||
445 | bb_info_msg("Found static lease: %x", static_lease_nip); | ||
446 | niro | 984 | memcpy(&fake_lease.lease_mac, &packet.chaddr, 6); |
447 | niro | 1123 | fake_lease.lease_nip = static_lease_nip; |
448 | niro | 984 | fake_lease.expires = 0; |
449 | lease = &fake_lease; | ||
450 | niro | 532 | } else { |
451 | niro | 984 | lease = find_lease_by_mac(packet.chaddr); |
452 | niro | 532 | } |
453 | |||
454 | niro | 1123 | /* Get REQUESTED_IP and SERVER_ID if present */ |
455 | server_id_opt = udhcp_get_option(&packet, DHCP_SERVER_ID); | ||
456 | if (server_id_opt) { | ||
457 | uint32_t server_id_net; | ||
458 | move_from_unaligned32(server_id_net, server_id_opt); | ||
459 | if (server_id_net != server_config.server_nip) { | ||
460 | /* client talks to somebody else */ | ||
461 | log1("server ID doesn't match, ignoring"); | ||
462 | continue; | ||
463 | } | ||
464 | } | ||
465 | requested_opt = udhcp_get_option(&packet, DHCP_REQUESTED_IP); | ||
466 | if (requested_opt) { | ||
467 | move_from_unaligned32(requested_nip, requested_opt); | ||
468 | } | ||
469 | |||
470 | niro | 532 | switch (state[0]) { |
471 | niro | 1123 | |
472 | niro | 532 | case DHCPDISCOVER: |
473 | niro | 984 | log1("Received DISCOVER"); |
474 | niro | 532 | |
475 | niro | 1123 | send_offer(&packet, static_lease_nip, lease); |
476 | niro | 532 | break; |
477 | |||
478 | niro | 1123 | case DHCPREQUEST: |
479 | niro | 984 | log1("Received REQUEST"); |
480 | niro | 1123 | /* RFC 2131: |
481 | niro | 532 | |
482 | niro | 1123 | o DHCPREQUEST generated during SELECTING state: |
483 | niro | 532 | |
484 | niro | 1123 | Client inserts the address of the selected server in 'server |
485 | identifier', 'ciaddr' MUST be zero, 'requested IP address' MUST be | ||
486 | filled in with the yiaddr value from the chosen DHCPOFFER. | ||
487 | niro | 532 | |
488 | niro | 1123 | Note that the client may choose to collect several DHCPOFFER |
489 | messages and select the "best" offer. The client indicates its | ||
490 | selection by identifying the offering server in the DHCPREQUEST | ||
491 | message. If the client receives no acceptable offers, the client | ||
492 | may choose to try another DHCPDISCOVER message. Therefore, the | ||
493 | servers may not receive a specific DHCPREQUEST from which they can | ||
494 | decide whether or not the client has accepted the offer. | ||
495 | niro | 532 | |
496 | niro | 1123 | o DHCPREQUEST generated during INIT-REBOOT state: |
497 | |||
498 | 'server identifier' MUST NOT be filled in, 'requested IP address' | ||
499 | option MUST be filled in with client's notion of its previously | ||
500 | assigned address. 'ciaddr' MUST be zero. The client is seeking to | ||
501 | verify a previously allocated, cached configuration. Server SHOULD | ||
502 | send a DHCPNAK message to the client if the 'requested IP address' | ||
503 | is incorrect, or is on the wrong network. | ||
504 | |||
505 | Determining whether a client in the INIT-REBOOT state is on the | ||
506 | correct network is done by examining the contents of 'giaddr', the | ||
507 | 'requested IP address' option, and a database lookup. If the DHCP | ||
508 | server detects that the client is on the wrong net (i.e., the | ||
509 | result of applying the local subnet mask or remote subnet mask (if | ||
510 | 'giaddr' is not zero) to 'requested IP address' option value | ||
511 | doesn't match reality), then the server SHOULD send a DHCPNAK | ||
512 | message to the client. | ||
513 | |||
514 | If the network is correct, then the DHCP server should check if | ||
515 | the client's notion of its IP address is correct. If not, then the | ||
516 | server SHOULD send a DHCPNAK message to the client. If the DHCP | ||
517 | server has no record of this client, then it MUST remain silent, | ||
518 | and MAY output a warning to the network administrator. This | ||
519 | behavior is necessary for peaceful coexistence of non- | ||
520 | communicating DHCP servers on the same wire. | ||
521 | |||
522 | If 'giaddr' is 0x0 in the DHCPREQUEST message, the client is on | ||
523 | the same subnet as the server. The server MUST broadcast the | ||
524 | DHCPNAK message to the 0xffffffff broadcast address because the | ||
525 | client may not have a correct network address or subnet mask, and | ||
526 | the client may not be answering ARP requests. | ||
527 | |||
528 | If 'giaddr' is set in the DHCPREQUEST message, the client is on a | ||
529 | different subnet. The server MUST set the broadcast bit in the | ||
530 | DHCPNAK, so that the relay agent will broadcast the DHCPNAK to the | ||
531 | client, because the client may not have a correct network address | ||
532 | or subnet mask, and the client may not be answering ARP requests. | ||
533 | |||
534 | o DHCPREQUEST generated during RENEWING state: | ||
535 | |||
536 | 'server identifier' MUST NOT be filled in, 'requested IP address' | ||
537 | option MUST NOT be filled in, 'ciaddr' MUST be filled in with | ||
538 | client's IP address. In this situation, the client is completely | ||
539 | configured, and is trying to extend its lease. This message will | ||
540 | be unicast, so no relay agents will be involved in its | ||
541 | transmission. Because 'giaddr' is therefore not filled in, the | ||
542 | DHCP server will trust the value in 'ciaddr', and use it when | ||
543 | replying to the client. | ||
544 | |||
545 | A client MAY choose to renew or extend its lease prior to T1. The | ||
546 | server may choose not to extend the lease (as a policy decision by | ||
547 | the network administrator), but should return a DHCPACK message | ||
548 | regardless. | ||
549 | |||
550 | o DHCPREQUEST generated during REBINDING state: | ||
551 | |||
552 | 'server identifier' MUST NOT be filled in, 'requested IP address' | ||
553 | option MUST NOT be filled in, 'ciaddr' MUST be filled in with | ||
554 | client's IP address. In this situation, the client is completely | ||
555 | configured, and is trying to extend its lease. This message MUST | ||
556 | be broadcast to the 0xffffffff IP broadcast address. The DHCP | ||
557 | server SHOULD check 'ciaddr' for correctness before replying to | ||
558 | the DHCPREQUEST. | ||
559 | |||
560 | The DHCPREQUEST from a REBINDING client is intended to accommodate | ||
561 | sites that have multiple DHCP servers and a mechanism for | ||
562 | maintaining consistency among leases managed by multiple servers. | ||
563 | A DHCP server MAY extend a client's lease only if it has local | ||
564 | administrative authority to do so. | ||
565 | */ | ||
566 | if (!requested_opt) { | ||
567 | requested_nip = packet.ciaddr; | ||
568 | if (requested_nip == 0) { | ||
569 | log1("no requested IP and no ciaddr, ignoring"); | ||
570 | break; | ||
571 | niro | 816 | } |
572 | niro | 532 | } |
573 | niro | 1123 | if (lease && requested_nip == lease->lease_nip) { |
574 | /* client requested or configured IP matches the lease. | ||
575 | * ACK it, and bump lease expiration time. */ | ||
576 | send_ACK(&packet, lease->lease_nip); | ||
577 | break; | ||
578 | } | ||
579 | if (server_id_opt) { | ||
580 | /* client was talking specifically to us. | ||
581 | * "No, we don't have this IP for you". */ | ||
582 | send_NAK(&packet); | ||
583 | } | ||
584 | niro | 532 | break; |
585 | niro | 1123 | |
586 | niro | 532 | case DHCPDECLINE: |
587 | niro | 1123 | /* RFC 2131: |
588 | * "If the server receives a DHCPDECLINE message, | ||
589 | * the client has discovered through some other means | ||
590 | * that the suggested network address is already | ||
591 | * in use. The server MUST mark the network address | ||
592 | * as not available and SHOULD notify the local | ||
593 | * sysadmin of a possible configuration problem." | ||
594 | * | ||
595 | * SERVER_ID must be present, | ||
596 | * REQUESTED_IP must be present, | ||
597 | * chaddr must be filled in, | ||
598 | * ciaddr must be 0 (we do not check this) | ||
599 | */ | ||
600 | niro | 984 | log1("Received DECLINE"); |
601 | niro | 1123 | if (server_id_opt |
602 | && requested_opt | ||
603 | && lease /* chaddr matches this lease */ | ||
604 | && requested_nip == lease->lease_nip | ||
605 | ) { | ||
606 | niro | 984 | memset(lease->lease_mac, 0, sizeof(lease->lease_mac)); |
607 | lease->expires = time(NULL) + server_config.decline_time; | ||
608 | niro | 532 | } |
609 | break; | ||
610 | niro | 1123 | |
611 | niro | 532 | case DHCPRELEASE: |
612 | niro | 1123 | /* "Upon receipt of a DHCPRELEASE message, the server |
613 | * marks the network address as not allocated." | ||
614 | * | ||
615 | * SERVER_ID must be present, | ||
616 | * REQUESTED_IP must not be present (we do not check this), | ||
617 | * chaddr must be filled in, | ||
618 | * ciaddr must be filled in | ||
619 | */ | ||
620 | niro | 984 | log1("Received RELEASE"); |
621 | niro | 1123 | if (server_id_opt |
622 | && lease /* chaddr matches this lease */ | ||
623 | && packet.ciaddr == lease->lease_nip | ||
624 | ) { | ||
625 | niro | 984 | lease->expires = time(NULL); |
626 | niro | 1123 | } |
627 | niro | 532 | break; |
628 | niro | 1123 | |
629 | niro | 532 | case DHCPINFORM: |
630 | niro | 984 | log1("Received INFORM"); |
631 | niro | 532 | send_inform(&packet); |
632 | break; | ||
633 | } | ||
634 | } | ||
635 | niro | 816 | ret0: |
636 | retval = 0; | ||
637 | ret: | ||
638 | /*if (server_config.pidfile) - server_config.pidfile is never NULL */ | ||
639 | remove_pidfile(server_config.pidfile); | ||
640 | return retval; | ||
641 | niro | 532 | } |