1 /* Copyright (c) 2008 The Board of Trustees of The Leland Stanford
4 * We are making the OpenFlow specification and associated documentation
5 * (Software) available for public use and benefit with the expectation
6 * that others will use, modify and enhance the Software and contribute
7 * those enhancements back to the community. However, since we would
8 * like to make the Software available for broadest use, with as few
9 * restrictions as possible permission is hereby granted, free of
10 * charge, to any person obtaining a copy of this Software to deal in
11 * the Software under the copyrights without restriction, including
12 * without limitation the rights to use, copy, modify, merge, publish,
13 * distribute, sublicense, and/or sell copies of the Software, and to
14 * permit persons to whom the Software is furnished to do so, subject to
15 * the following conditions:
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
24 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
25 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
26 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
29 * The name and trademarks of copyright holder(s) may NOT be used in
30 * advertising or publicity pertaining to the Software or any
31 * derivatives without specific, written prior permission.
35 #include "dhcp-client.h"
36 #include <arpa/inet.h>
43 #include <sys/types.h>
48 #include "dynamic-string.h"
52 #include "poll-loop.h"
56 #define THIS_MODULE VLM_dhcp_client
59 #define DHCLIENT_STATES \
60 DHCLIENT_STATE(INIT, 1 << 0) \
61 DHCLIENT_STATE(INIT_REBOOT, 1 << 1) \
62 DHCLIENT_STATE(REBOOTING, 1 << 2) \
63 DHCLIENT_STATE(SELECTING, 1 << 3) \
64 DHCLIENT_STATE(REQUESTING, 1 << 4) \
65 DHCLIENT_STATE(BOUND, 1 << 5) \
66 DHCLIENT_STATE(RENEWING, 1 << 6) \
67 DHCLIENT_STATE(REBINDING, 1 << 7) \
68 DHCLIENT_STATE(RELEASED, 1 << 8)
70 #define DHCLIENT_STATE(NAME, VALUE) S_##NAME = VALUE,
75 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(60, 60);
78 state_name(enum dhclient_state state)
81 #define DHCLIENT_STATE(NAME, VALUE) case S_##NAME: return #NAME;
90 struct netdev *netdev;
92 void (*modify_request)(struct dhcp_msg *, void *aux);
93 bool (*validate_offer)(const struct dhcp_msg *, void *aux);
97 enum dhclient_state state;
98 unsigned int state_entered; /* When we transitioned to this state. */
99 uint32_t xid; /* In host byte order. */
100 uint32_t ipaddr, netmask, router;
102 struct dhcp_msg *binding;
105 unsigned int retransmit, delay; /* Used by send_reliably(). */
107 unsigned int init_delay; /* Used by S_INIT. */
109 time_t lease_expiration;
110 unsigned int bound_timeout;
111 unsigned int renewing_timeout;
112 unsigned int rebinding_timeout;
114 /* Used by dhclient_run() and dhclient_wait() */
115 unsigned int min_timeout;
118 /* Set when we send out a DHCPDISCOVER message. */
124 /* Minimum acceptable lease time, in seconds. */
125 #define MIN_ACCEPTABLE_LEASE 15
127 static void state_transition(struct dhclient *, enum dhclient_state);
128 static unsigned int elapsed_in_this_state(const struct dhclient *cli);
129 static bool timeout(struct dhclient *, unsigned int secs);
131 static void dhclient_msg_init(struct dhclient *, enum dhcp_msg_type,
133 static void send_reliably(struct dhclient *cli,
134 void (*make_packet)(struct dhclient *,
136 static bool do_receive_msg(struct dhclient *, struct dhcp_msg *);
137 static void do_send_msg(struct dhclient *, const struct dhcp_msg *);
138 static bool receive_ack(struct dhclient *);
140 static unsigned int fuzz(unsigned int x, int max_fuzz);
141 static unsigned int calc_t2(unsigned int lease);
142 static unsigned int calc_t1(unsigned int lease, unsigned int t2);
144 static unsigned int clamp(unsigned int x, unsigned int min, unsigned int max);
146 /* Creates a new DHCP client to configure the network device 'netdev_name'
149 * If 'modify_request' is non-null, then each DHCP message to discover or
150 * request an address will be passed to it (along with auxiliary data 'aux').
151 * It may then add any desired options to the message for transmission.
153 * If 'validate_offer' is non-null, then each DHCP message that offers an
154 * address will be passed to it (along with auxiliary data 'aux') for
155 * validation: if it returns true, the address will accepted; otherwise, it
158 * The DHCP client will not start advertising for an IP address until
159 * dhclient_init() is called.
161 * If successful, returns 0 and sets '*cli' to the new DHCP client. Otherwise,
162 * returns a positive errno value and sets '*cli' to a null pointer. */
164 dhclient_create(const char *netdev_name,
165 void (*modify_request)(struct dhcp_msg *, void *aux),
166 bool (*validate_offer)(const struct dhcp_msg *, void *aux),
167 void *aux, struct dhclient **cli_)
169 struct dhclient *cli;
170 struct netdev *netdev;
175 error = netdev_open(netdev_name, ETH_TYPE_IP, &netdev);
176 /* XXX install socket filter to catch only DHCP packets. */
178 VLOG_ERR("could not open %s network device: %s",
179 netdev_name, strerror(error));
183 error = netdev_turn_flags_on(netdev, NETDEV_UP, false);
185 VLOG_ERR("could not bring %s device up: %s",
186 netdev_name, strerror(error));
187 netdev_close(netdev);
191 cli = xcalloc(1, sizeof *cli);
192 cli->modify_request = modify_request;
193 cli->validate_offer = validate_offer;
195 cli->netdev = netdev;
196 cli->state = S_RELEASED;
197 cli->state_entered = time_now();
198 cli->xid = random_uint32();
201 cli->retransmit = cli->delay = 0;
202 cli->min_timeout = 1;
209 /* Destroys 'cli' and frees all related resources. */
211 dhclient_destroy(struct dhclient *cli)
214 dhcp_msg_uninit(cli->binding);
216 netdev_close(cli->netdev);
222 /* Forces 'cli' into a (re)initialization state, in which no address is bound
223 * but the client is advertising to obtain one. If 'requested_ip' is nonzero,
224 * then the client will attempt to re-bind to that IP address; otherwise, it
225 * will not ask for any particular address. */
227 dhclient_init(struct dhclient *cli, uint32_t requested_ip)
229 state_transition(cli, requested_ip ? S_INIT_REBOOT : S_INIT);
230 cli->ipaddr = requested_ip;
231 cli->min_timeout = 0;
235 /* Forces 'cli' to release its bound IP address (if any). The client will not
236 * advertise for a new address until dhclient_init() is called again. */
238 dhclient_release(struct dhclient *cli)
240 if (dhclient_is_bound(cli)) {
242 dhclient_msg_init(cli, DHCPRELEASE, &msg);
243 msg.ciaddr = cli->ipaddr;
244 do_send_msg(cli, &msg);
245 dhcp_msg_uninit(&msg);
247 state_transition(cli, S_RELEASED);
248 cli->min_timeout = UINT_MAX;
252 do_force_renew(struct dhclient *cli, int deadline)
254 time_t now = time_now();
255 unsigned int lease_left = sat_sub(cli->lease_expiration, now);
256 if (lease_left <= deadline) {
257 if (cli->state & (S_RENEWING | S_REBINDING)) {
260 deadline = lease_left;
262 if (cli->state & (S_BOUND | S_RENEWING)) {
263 state_transition(cli, S_RENEWING);
264 cli->renewing_timeout = deadline * 3 / 4;
265 cli->rebinding_timeout = deadline * 1 / 4;
267 state_transition(cli, S_REBINDING);
268 cli->rebinding_timeout = deadline;
270 cli->min_timeout = 0;
273 /* Forces 'cli' to attempt to renew the lease its current IP address (if any)
274 * within 'deadline' seconds. If the deadline is not met, then the client
275 * gives up its IP address binding and re-starts the DHCP process. */
277 dhclient_force_renew(struct dhclient *cli, int deadline)
279 /* Drain the receive queue so that we know that any DHCPACK we process is
280 * freshly received. */
281 netdev_drain(cli->netdev);
283 switch (cli->state) {
294 do_force_renew(cli, deadline);
298 dhclient_init(cli, 0);
303 /* Returns true if 'cli' is bound to an IP address, false otherwise. */
305 dhclient_is_bound(const struct dhclient *cli)
307 return cli->state & (S_BOUND | S_RENEWING | S_REBINDING);
310 /* Returns true if 'cli' has changed from bound to unbound, or vice versa, at
311 * least once since the last time this function was called. */
313 dhclient_changed(struct dhclient *cli)
315 bool changed = cli->changed;
320 /* Returns 'cli''s current state, as a string. The caller must not modify or
321 * free the string. */
323 dhclient_get_state(const struct dhclient *cli)
325 return state_name(cli->state);
328 /* Returns the number of seconds spent so far in 'cli''s current state. */
330 dhclient_get_state_elapsed(const struct dhclient *cli)
332 return elapsed_in_this_state(cli);
335 /* If 'cli' is bound, returns the number of seconds remaining in its lease;
336 * otherwise, returns 0. */
338 dhclient_get_lease_remaining(const struct dhclient *cli)
340 return dhclient_is_bound(cli) ? cli->lease_expiration - time_now() : 0;
343 /* If 'cli' is bound to an IP address, returns that IP address; otherwise,
346 dhclient_get_ip(const struct dhclient *cli)
348 return dhclient_is_bound(cli) ? cli->ipaddr : 0;
351 /* If 'cli' is bound to an IP address, returns the netmask for that IP address;
352 * otherwise, returns 0. */
354 dhclient_get_netmask(const struct dhclient *cli)
356 return dhclient_is_bound(cli) ? cli->netmask : 0;
359 /* If 'cli' is bound to an IP address and 'cli' has a default gateway, returns
360 * that default gateway; otherwise, returns 0. */
362 dhclient_get_router(const struct dhclient *cli)
364 return dhclient_is_bound(cli) ? cli->router : 0;
367 /* If 'cli' is bound to an IP address, returns the DHCP message that was
368 * received to obtain that IP address (so that the caller can obtain additional
369 * options from it). Otherwise, returns a null pointer. */
370 const struct dhcp_msg *
371 dhclient_get_config(const struct dhclient *cli)
373 return dhclient_is_bound(cli) ? cli->binding : NULL;
376 /* Configures the network device backing 'cli' to the network address and other
377 * parameters obtained via DHCP. If no address is bound on 'cli', removes any
378 * configured address from 'cli'.
380 * To use a dhclient as a regular DHCP client that binds and unbinds from IP
381 * addresses in the usual fashion, call this function after dhclient_run() if
382 * anything has changed, like so:
385 * if (dhclient_changed(cli)) {
386 * dhclient_configure_netdev(cli);
391 dhclient_configure_netdev(struct dhclient *cli)
393 struct in_addr addr = { dhclient_get_ip(cli) };
394 struct in_addr mask = { dhclient_get_netmask(cli) };
395 struct in_addr router = { dhclient_get_router(cli) };
398 error = netdev_set_in4(cli->netdev, addr, mask);
400 VLOG_ERR("could not set %s address "IP_FMT"/"IP_FMT": %s",
401 netdev_get_name(cli->netdev),
402 IP_ARGS(&addr.s_addr), IP_ARGS(&mask.s_addr),
406 if (!error && router.s_addr) {
407 error = netdev_add_router(cli->netdev, router);
409 VLOG_ERR("failed to add default route to "IP_FMT" on %s: %s",
410 IP_ARGS(&router), netdev_get_name(cli->netdev),
418 /* If 'cli' is bound and the binding includes DNS domain parameters, updates
419 * /etc/resolv.conf will be updated to match the received parameters. Returns
420 * 0 if successful, otherwise a positive errno value. */
422 dhclient_update_resolv_conf(struct dhclient *cli)
426 bool has_domain_name;
431 if (!dhclient_is_bound(cli)) {
434 if (!dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER, 0, &dns_server)) {
435 VLOG_DBG("binding does not include any DNS servers");
439 sprintf(new_name, "/etc/resolv.conf.tmp%ld", (long int) getpid());
440 new = fopen(new_name, "w");
442 VLOG_WARN("%s: create: %s", new_name, strerror(errno));
446 domain_name = dhcp_msg_get_string(cli->binding, DHCP_CODE_DOMAIN_NAME);
447 has_domain_name = domain_name != NULL;
449 if (strspn(domain_name, "-_.0123456789abcdefghijklmnopqrstuvwxyz"
450 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == strlen(domain_name)) {
451 fprintf(new, "domain %s\n", domain_name);
453 VLOG_WARN("ignoring invalid domain name %s", domain_name);
454 has_domain_name = false;
457 VLOG_DBG("binding does not include domain name");
461 for (i = 0; dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER,
462 i, &dns_server); i++) {
463 fprintf(new, "nameserver "IP_FMT"\n", IP_ARGS(&dns_server));
466 old = fopen("/etc/resolv.conf", "r");
470 while (fgets(line, sizeof line, old)) {
471 char *kw = xmemdup0(line, strcspn(line, " \t\r\n"));
472 if (strcmp(kw, "nameserver")
474 || (strcmp(kw, "domain") && strcmp(kw, "search")))) {
481 VLOG_DBG("/etc/resolv.conf: open: %s", strerror(errno));
484 if (fclose(new) < 0) {
485 VLOG_WARN("%s: close: %s", new_name, strerror(errno));
489 if (rename(new_name, "/etc/resolv.conf") < 0) {
490 VLOG_WARN("failed to rename %s to /etc/resolv.conf: %s",
491 new_name, strerror(errno));
501 make_dhcpdiscover(struct dhclient *cli, struct dhcp_msg *msg)
503 cli->secs = elapsed_in_this_state(cli);
504 dhclient_msg_init(cli, DHCPDISCOVER, msg);
506 dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr);
511 make_dhcprequest(struct dhclient *cli, struct dhcp_msg *msg)
513 dhclient_msg_init(cli, DHCPREQUEST, msg);
514 msg->ciaddr = dhclient_get_ip(cli);
515 if (cli->state == S_REQUESTING) {
516 dhcp_msg_put_ip(msg, DHCP_CODE_SERVER_IDENTIFIER, cli->server_ip);
518 dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr);
522 do_init(struct dhclient *cli, enum dhclient_state next_state)
524 if (!cli->init_delay) {
525 cli->init_delay = fuzz(2, 1);
527 if (timeout(cli, cli->init_delay)) {
528 state_transition(cli, next_state);
533 dhclient_run_INIT(struct dhclient *cli)
535 do_init(cli, S_SELECTING);
539 dhclient_run_INIT_REBOOT(struct dhclient *cli)
541 do_init(cli, S_REBOOTING);
545 dhclient_run_REBOOTING(struct dhclient *cli)
547 send_reliably(cli, make_dhcprequest);
548 if (!receive_ack(cli) && timeout(cli, 60)) {
549 state_transition(cli, S_INIT);
554 dhcp_receive(struct dhclient *cli, unsigned int msgs, struct dhcp_msg *msg)
556 while (do_receive_msg(cli, msg)) {
557 if (msg->type < 0 || msg->type > 31 || !((1u << msg->type) & msgs)) {
558 VLOG_DBG_RL(&rl, "received unexpected %s in %s state: %s",
559 dhcp_type_name(msg->type), state_name(cli->state),
560 dhcp_msg_to_string(msg, false, &cli->s));
561 } else if (msg->xid != cli->xid) {
563 "ignoring %s with xid != %08"PRIx32" in %s state: %s",
564 dhcp_type_name(msg->type), msg->xid,
565 state_name(cli->state),
566 dhcp_msg_to_string(msg, false, &cli->s));
570 dhcp_msg_uninit(msg);
576 validate_offered_options(struct dhclient *cli, const struct dhcp_msg *msg)
578 uint32_t lease, netmask;
579 if (!dhcp_msg_get_secs(msg, DHCP_CODE_LEASE_TIME, 0, &lease)) {
580 VLOG_WARN_RL(&rl, "%s lacks lease time: %s", dhcp_type_name(msg->type),
581 dhcp_msg_to_string(msg, false, &cli->s));
582 } else if (!dhcp_msg_get_ip(msg, DHCP_CODE_SUBNET_MASK, 0, &netmask)) {
583 VLOG_WARN_RL(&rl, "%s lacks netmask: %s", dhcp_type_name(msg->type),
584 dhcp_msg_to_string(msg, false, &cli->s));
585 } else if (lease < MIN_ACCEPTABLE_LEASE) {
586 VLOG_WARN_RL(&rl, "Ignoring %s with %"PRIu32"-second lease time: %s",
587 dhcp_type_name(msg->type), lease,
588 dhcp_msg_to_string(msg, false, &cli->s));
589 } else if (cli->validate_offer && !cli->validate_offer(msg, cli->aux)) {
590 VLOG_DBG_RL(&rl, "client validation hook refused offer: %s",
591 dhcp_msg_to_string(msg, false, &cli->s));
599 dhclient_run_SELECTING(struct dhclient *cli)
603 send_reliably(cli, make_dhcpdiscover);
604 if (cli->server_ip && timeout(cli, 60)) {
606 state_transition(cli, S_INIT);
608 for (; dhcp_receive(cli, 1u << DHCPOFFER, &msg); dhcp_msg_uninit(&msg)) {
609 if (!validate_offered_options(cli, &msg)) {
612 if (!dhcp_msg_get_ip(&msg, DHCP_CODE_SERVER_IDENTIFIER,
613 0, &cli->server_ip)) {
614 VLOG_WARN_RL(&rl, "DHCPOFFER lacks server identifier: %s",
615 dhcp_msg_to_string(&msg, false, &cli->s));
619 VLOG_DBG_RL(&rl, "accepting DHCPOFFER: %s",
620 dhcp_msg_to_string(&msg, false, &cli->s));
621 cli->ipaddr = msg.yiaddr;
622 state_transition(cli, S_REQUESTING);
628 same_binding(const struct dhcp_msg *old, const struct dhcp_msg *new)
630 static const int codes[] = {
631 DHCP_CODE_SUBNET_MASK,
633 DHCP_CODE_DNS_SERVER,
635 DHCP_CODE_DOMAIN_NAME,
638 DHCP_CODE_BROADCAST_ADDRESS,
639 DHCP_CODE_STATIC_ROUTE,
640 DHCP_CODE_ARP_CACHE_TIMEOUT,
641 DHCP_CODE_ETHERNET_ENCAPSULATION,
643 DHCP_CODE_SERVER_IDENTIFIER,
644 DHCP_CODE_OFP_CONTROLLER_VCONN,
645 DHCP_CODE_OFP_PKI_URI,
650 if (old->yiaddr != new->yiaddr) {
651 VLOG_WARN("DHCP binding changed IP address from "IP_FMT" to "IP_FMT,
652 IP_ARGS(&old->yiaddr), IP_ARGS(&new->yiaddr));
655 for (i = 0; i < ARRAY_SIZE(codes); i++) {
657 const struct dhcp_option *old_opt = &old->options[code];
658 const struct dhcp_option *new_opt = &new->options[code];
659 if (!dhcp_option_equals(old_opt, new_opt)) {
660 struct ds old_string = DS_EMPTY_INITIALIZER;
661 struct ds new_string = DS_EMPTY_INITIALIZER;
662 VLOG_WARN("DHCP binding changed option from %s to %s",
663 dhcp_option_to_string(old_opt, code, &old_string),
664 dhcp_option_to_string(new_opt, code, &new_string));
665 ds_destroy(&old_string);
666 ds_destroy(&new_string);
674 receive_ack(struct dhclient *cli)
678 if (!dhcp_receive(cli, (1u << DHCPACK) | (1u << DHCPNAK), &msg)) {
680 } else if (msg.type == DHCPNAK) {
681 dhcp_msg_uninit(&msg);
682 state_transition(cli, S_INIT);
684 } else if (!validate_offered_options(cli, &msg)) {
685 dhcp_msg_uninit(&msg);
688 uint32_t lease = 0, t1 = 0, t2 = 0;
691 if (!same_binding(cli->binding, &msg)) {
694 dhcp_msg_uninit(cli->binding);
696 cli->binding = xmalloc(sizeof *cli->binding);
698 dhcp_msg_copy(cli->binding, &msg);
700 dhcp_msg_get_secs(&msg, DHCP_CODE_LEASE_TIME, 0, &lease);
701 dhcp_msg_get_secs(&msg, DHCP_CODE_T1, 0, &t1);
702 dhcp_msg_get_secs(&msg, DHCP_CODE_T2, 0, &t2);
703 assert(lease >= MIN_ACCEPTABLE_LEASE);
705 if (!t2 || t2 >= lease) {
708 if (!t1 || t1 >= t2) {
709 t1 = calc_t1(lease, t2);
712 cli->lease_expiration = sat_add(time_now(), lease);
713 cli->bound_timeout = t1;
714 cli->renewing_timeout = t2 - t1;
715 cli->rebinding_timeout = lease - t2;
717 cli->ipaddr = msg.yiaddr;
718 dhcp_msg_get_ip(&msg, DHCP_CODE_SUBNET_MASK, 0, &cli->netmask);
719 if (!dhcp_msg_get_ip(&msg, DHCP_CODE_ROUTER, 0, &cli->router)) {
720 cli->router = INADDR_ANY;
722 state_transition(cli, S_BOUND);
723 VLOG_DBG("Bound: %s", dhcp_msg_to_string(&msg, false, &cli->s));
729 dhclient_run_REQUESTING(struct dhclient *cli)
731 send_reliably(cli, make_dhcprequest);
732 if (!receive_ack(cli) && timeout(cli, 60)) {
733 state_transition(cli, S_INIT);
738 dhclient_run_BOUND(struct dhclient *cli)
740 if (timeout(cli, cli->bound_timeout)) {
741 state_transition(cli, S_RENEWING);
746 dhclient_run_RENEWING(struct dhclient *cli)
748 send_reliably(cli, make_dhcprequest);
749 if (!receive_ack(cli) && timeout(cli, cli->renewing_timeout)) {
750 state_transition(cli, S_REBINDING);
755 dhclient_run_REBINDING(struct dhclient *cli)
757 send_reliably(cli, make_dhcprequest);
758 if (!receive_ack(cli) && timeout(cli, cli->rebinding_timeout)) {
759 state_transition(cli, S_INIT);
764 dhclient_run_RELEASED(struct dhclient *cli UNUSED)
769 /* Processes the DHCP protocol for 'cli'. */
771 dhclient_run(struct dhclient *cli)
775 old_state = cli->state;
776 cli->min_timeout = UINT_MAX;
778 switch (cli->state) {
779 #define DHCLIENT_STATE(NAME, VALUE) \
780 case S_##NAME: dhclient_run_##NAME(cli); break;
782 #undef DHCLIENT_STATE
786 } while (cli->state != old_state);
789 /* Sets up poll timeouts to wake up the poll loop when 'cli' needs to do some
792 dhclient_wait(struct dhclient *cli)
794 if (cli->min_timeout != UINT_MAX) {
795 poll_timer_wait(sat_mul(cli->min_timeout, 1000));
797 /* Reset timeout to 1 second. This will have no effect ordinarily, because
798 * dhclient_run() will typically set it back to a higher value. If,
799 * however, the caller fails to call dhclient_run() before its next call to
800 * dhclient_wait() we won't potentially block forever. */
801 cli->min_timeout = 1;
803 if (cli->state & (S_SELECTING | S_REQUESTING | S_RENEWING | S_REBINDING)) {
804 netdev_recv_wait(cli->netdev);
809 state_transition(struct dhclient *cli, enum dhclient_state state)
811 bool was_bound = dhclient_is_bound(cli);
813 if (cli->state != state) {
814 VLOG_DBG("entering %s", state_name(state));
817 cli->state_entered = time_now();
818 cli->retransmit = cli->delay = 0;
819 am_bound = dhclient_is_bound(cli);
820 if (was_bound != am_bound) {
823 assert(cli->binding != NULL);
824 VLOG_WARN("%s: obtained address "IP_FMT", netmask "IP_FMT,
825 netdev_get_name(cli->netdev),
826 IP_ARGS(&cli->ipaddr), IP_ARGS(&cli->netmask));
828 VLOG_WARN("%s: obtained default gateway "IP_FMT,
829 netdev_get_name(cli->netdev), IP_ARGS(&cli->router));
832 dhcp_msg_uninit(cli->binding);
836 VLOG_WARN("%s: network address unbound",
837 netdev_get_name(cli->netdev));
840 if (cli->state & (S_SELECTING | S_REQUESTING | S_REBOOTING)) {
841 netdev_drain(cli->netdev);
846 send_reliably(struct dhclient *cli,
847 void (*make_packet)(struct dhclient *, struct dhcp_msg *))
849 if (timeout(cli, cli->retransmit)) {
851 make_packet(cli, &msg);
852 if (cli->modify_request) {
853 cli->modify_request(&msg, cli->aux);
855 do_send_msg(cli, &msg);
856 cli->delay = MIN(64, MAX(4, cli->delay * 2));
857 cli->retransmit += fuzz(cli->delay, 1);
858 timeout(cli, cli->retransmit);
859 dhcp_msg_uninit(&msg);
864 dhclient_msg_init(struct dhclient *cli, enum dhcp_msg_type type,
865 struct dhcp_msg *msg)
868 msg->op = DHCP_BOOTREQUEST;
870 msg->secs = cli->secs;
872 memcpy(msg->chaddr, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN);
876 elapsed_in_this_state(const struct dhclient *cli)
878 return time_now() - cli->state_entered;
882 timeout(struct dhclient *cli, unsigned int secs)
884 cli->min_timeout = MIN(cli->min_timeout, secs);
885 return time_now() >= sat_add(cli->state_entered, secs);
889 do_receive_msg(struct dhclient *cli, struct dhcp_msg *msg)
893 ofpbuf_init(&b, netdev_get_mtu(cli->netdev) + VLAN_ETH_HEADER_LEN);
894 for (; cli->received < 50; cli->received++) {
895 const struct ip_header *ip;
896 const struct dhcp_header *dhcp;
901 error = netdev_recv(cli->netdev, &b);
906 flow_extract(&b, 0, &flow);
907 if (flow.dl_type != htons(ETH_TYPE_IP)
908 || flow.nw_proto != IP_TYPE_UDP
909 || flow.tp_dst != htons(68)
910 || !(eth_addr_is_broadcast(flow.dl_dst)
911 || eth_addr_equals(flow.dl_dst,
912 netdev_get_etheraddr(cli->netdev)))) {
917 if (IP_IS_FRAGMENT(ip->ip_frag_off)) {
918 /* We don't do reassembly. */
919 VLOG_WARN_RL(&rl, "ignoring fragmented DHCP datagram");
925 VLOG_WARN_RL(&rl, "ignoring DHCP datagram with missing payload");
929 ofpbuf_pull(&b, (char *)b.l7 - (char*)b.data);
930 error = dhcp_parse(msg, &b);
932 VLOG_DBG_RL(&rl, "received %s",
933 dhcp_msg_to_string(msg, false, &cli->s));
938 netdev_drain(cli->netdev);
945 do_send_msg(struct dhclient *cli, const struct dhcp_msg *msg)
948 struct eth_header eh;
950 struct udp_header th;
954 ofpbuf_init(&b, ETH_TOTAL_MAX);
955 ofpbuf_reserve(&b, ETH_HEADER_LEN + IP_HEADER_LEN + UDP_HEADER_LEN);
957 dhcp_assemble(msg, &b);
959 memcpy(eh.eth_src, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN);
960 memcpy(eh.eth_dst, eth_addr_broadcast, ETH_ADDR_LEN);
961 eh.eth_type = htons(ETH_TYPE_IP);
963 nh.ip_ihl_ver = IP_IHL_VER(5, IP_VERSION);
965 nh.ip_tot_len = htons(IP_HEADER_LEN + UDP_HEADER_LEN + b.size);
966 /* We can't guarantee uniqueness of ip_id versus the host's, screwing up
967 * fragment reassembly, so prevent fragmentation and use an all-zeros
968 * ip_id. RFC 791 doesn't say we can do this, but Linux does the same
969 * thing for DF packets, so it must not screw anything up. */
971 nh.ip_frag_off = htons(IP_DONT_FRAGMENT);
973 nh.ip_proto = IP_TYPE_UDP;
975 nh.ip_src = dhclient_get_ip(cli);
976 /* XXX need to use UDP socket for nonzero server IPs so that we can get
977 * routing table support.
979 * if (...have server IP and in appropriate state...) {
980 * nh.ip_dst = cli->server_ip;
982 * nh.ip_dst = INADDR_BROADCAST;
985 nh.ip_dst = INADDR_BROADCAST;
986 nh.ip_csum = csum(&nh, sizeof nh);
988 th.udp_src = htons(66);
989 th.udp_dst = htons(67);
990 th.udp_len = htons(UDP_HEADER_LEN + b.size);
992 udp_csum = csum_add32(0, nh.ip_src);
993 udp_csum = csum_add32(udp_csum, nh.ip_dst);
994 udp_csum = csum_add16(udp_csum, IP_TYPE_UDP << 8);
995 udp_csum = csum_add16(udp_csum, th.udp_len);
996 udp_csum = csum_continue(udp_csum, &th, sizeof th);
997 th.udp_csum = csum_finish(csum_continue(udp_csum, b.data, b.size));
999 ofpbuf_push(&b, &th, sizeof th);
1000 ofpbuf_push(&b, &nh, sizeof nh);
1001 ofpbuf_push(&b, &eh, sizeof eh);
1003 /* Don't try to send the frame if it's too long for an Ethernet frame. We
1004 * disregard the network device's actual MTU because we don't want the
1005 * frame to have to be discarded or fragmented if it travels over a regular
1006 * Ethernet at some point. 1500 bytes should be enough for anyone. */
1007 if (b.size <= ETH_TOTAL_MAX) {
1008 VLOG_DBG("sending %s", dhcp_msg_to_string(msg, false, &cli->s));
1009 error = netdev_send(cli->netdev, &b);
1011 VLOG_ERR("send failed on %s: %s",
1012 netdev_get_name(cli->netdev), strerror(error));
1015 VLOG_ERR("cannot send %zu-byte Ethernet frame", b.size);
1022 fuzz(unsigned int x, int max_fuzz)
1024 /* Generate number in range [-max_fuzz, +max_fuzz]. */
1025 int fuzz = random_range(max_fuzz * 2 + 1) - max_fuzz;
1026 unsigned int y = x + fuzz;
1027 return fuzz >= 0 ? (y >= x ? y : UINT_MAX) : (y <= x ? y : 0);
1031 clamp(unsigned int x, unsigned int min, unsigned int max)
1033 return x < min ? min : x > max ? max : x;
1037 calc_t2(unsigned int lease)
1039 unsigned int base = lease * 0.875;
1040 return lease >= 60 ? clamp(fuzz(base, 10), 0, lease - 1) : base;
1044 calc_t1(unsigned int lease, unsigned int t2)
1046 unsigned int base = lease / 2;
1047 return lease >= 60 ? clamp(fuzz(base, 10), 0, t2 - 1) : base;