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>
49 #include "dynamic-string.h"
52 #include "ofp-print.h"
53 #include "poll-loop.h"
57 #define THIS_MODULE VLM_dhcp_client
60 #define DHCLIENT_STATES \
61 DHCLIENT_STATE(INIT, 1 << 0) \
62 DHCLIENT_STATE(INIT_REBOOT, 1 << 1) \
63 DHCLIENT_STATE(REBOOTING, 1 << 2) \
64 DHCLIENT_STATE(SELECTING, 1 << 3) \
65 DHCLIENT_STATE(REQUESTING, 1 << 4) \
66 DHCLIENT_STATE(BOUND, 1 << 5) \
67 DHCLIENT_STATE(RENEWING, 1 << 6) \
68 DHCLIENT_STATE(REBINDING, 1 << 7) \
69 DHCLIENT_STATE(RELEASED, 1 << 8)
71 #define DHCLIENT_STATE(NAME, VALUE) S_##NAME = VALUE,
77 state_name(enum dhclient_state state)
80 #define DHCLIENT_STATE(NAME, VALUE) case S_##NAME: return #NAME;
89 struct netdev *netdev;
91 void (*modify_request)(struct dhcp_msg *, void *aux);
92 bool (*validate_offer)(const struct dhcp_msg *, void *aux);
96 enum dhclient_state state;
97 unsigned int state_entered; /* When we transitioned to this state. */
98 uint32_t xid; /* In host byte order. */
99 uint32_t ipaddr, netmask, router;
101 struct dhcp_msg *binding;
104 unsigned int retransmit, delay; /* Used by send_reliably(). */
106 unsigned int init_delay; /* Used by S_INIT. */
108 time_t lease_expiration;
109 unsigned int bound_timeout;
110 unsigned int renewing_timeout;
111 unsigned int rebinding_timeout;
113 /* Used by dhclient_run() and dhclient_wait() */
114 unsigned int min_timeout;
117 /* Set when we send out a DHCPDISCOVER message. */
123 /* Minimum acceptable lease time, in seconds. */
124 #define MIN_ACCEPTABLE_LEASE 15
126 static void state_transition(struct dhclient *, enum dhclient_state);
127 static unsigned int elapsed_in_this_state(const struct dhclient *cli);
128 static bool timeout(struct dhclient *, unsigned int secs);
130 static void dhclient_msg_init(struct dhclient *, enum dhcp_msg_type,
132 static void send_reliably(struct dhclient *cli,
133 void (*make_packet)(struct dhclient *,
135 static bool do_receive_msg(struct dhclient *, struct dhcp_msg *);
136 static void do_send_msg(struct dhclient *, const struct dhcp_msg *);
137 static bool receive_ack(struct dhclient *);
139 static unsigned int fuzz(unsigned int x, int max_fuzz);
140 static unsigned int calc_t2(unsigned int lease);
141 static unsigned int calc_t1(unsigned int lease, unsigned int t2);
143 static unsigned int clamp(unsigned int x, unsigned int min, unsigned int max);
145 /* Creates a new DHCP client to configure the network device 'netdev_name'
148 * If 'modify_request' is non-null, then each DHCP message to discover or
149 * request an address will be passed to it (along with auxiliary data 'aux').
150 * It may then add any desired options to the message for transmission.
152 * If 'validate_offer' is non-null, then each DHCP message that offers an
153 * address will be passed to it (along with auxiliary data 'aux') for
154 * validation: if it returns true, the address will accepted; otherwise, it
157 * The DHCP client will not start advertising for an IP address until
158 * dhclient_init() is called.
160 * If successful, returns 0 and sets '*cli' to the new DHCP client. Otherwise,
161 * returns a positive errno value and sets '*cli' to a null pointer. */
163 dhclient_create(const char *netdev_name,
164 void (*modify_request)(struct dhcp_msg *, void *aux),
165 bool (*validate_offer)(const struct dhcp_msg *, void *aux),
166 void *aux, struct dhclient **cli_)
168 struct dhclient *cli;
169 struct netdev *netdev;
174 error = netdev_open(netdev_name, ETH_TYPE_IP, &netdev);
175 /* XXX install socket filter to catch only DHCP packets. */
177 VLOG_ERR("could not open %s network device: %s",
178 netdev_name, strerror(error));
182 error = netdev_turn_flags_on(netdev, NETDEV_UP, false);
184 VLOG_ERR("could not bring %s device up: %s",
185 netdev_name, strerror(error));
186 netdev_close(netdev);
190 cli = xcalloc(1, sizeof *cli);
191 cli->modify_request = modify_request;
192 cli->validate_offer = validate_offer;
194 cli->netdev = netdev;
195 cli->state = S_RELEASED;
196 cli->state_entered = time_now();
197 cli->xid = random_uint32();
200 cli->retransmit = cli->delay = 0;
201 cli->min_timeout = 1;
208 /* Forces 'cli' into a (re)initialization state, in which no address is bound
209 * but the client is advertising to obtain one. If 'requested_ip' is nonzero,
210 * then the client will attempt to re-bind to that IP address; otherwise, it
211 * will not ask for any particular address. */
213 dhclient_init(struct dhclient *cli, uint32_t requested_ip)
215 state_transition(cli, requested_ip ? S_INIT_REBOOT : S_INIT);
216 cli->ipaddr = requested_ip;
217 cli->min_timeout = 0;
221 /* Forces 'cli' to release its bound IP address (if any). The client will not
222 * advertise for a new address until dhclient_init() is called again. */
224 dhclient_release(struct dhclient *cli)
226 if (dhclient_is_bound(cli)) {
228 dhclient_msg_init(cli, DHCPRELEASE, &msg);
229 msg.ciaddr = cli->ipaddr;
230 do_send_msg(cli, &msg);
231 dhcp_msg_uninit(&msg);
233 state_transition(cli, S_RELEASED);
234 cli->min_timeout = UINT_MAX;
238 do_force_renew(struct dhclient *cli, int deadline)
240 time_t now = time_now();
241 unsigned int lease_left = sat_sub(cli->lease_expiration, now);
242 if (lease_left <= deadline) {
243 if (cli->state & (S_RENEWING | S_REBINDING)) {
246 deadline = lease_left;
248 if (cli->state & (S_BOUND | S_RENEWING)) {
249 state_transition(cli, S_RENEWING);
250 cli->renewing_timeout = deadline * 3 / 4;
251 cli->rebinding_timeout = deadline * 1 / 4;
253 state_transition(cli, S_REBINDING);
254 cli->rebinding_timeout = deadline;
256 cli->min_timeout = 0;
259 /* Forces 'cli' to attempt to renew the lease its current IP address (if any)
260 * within 'deadline' seconds. If the deadline is not met, then the client
261 * gives up its IP address binding and re-starts the DHCP process. */
263 dhclient_force_renew(struct dhclient *cli, int deadline)
265 /* Drain the receive queue so that we know that any DHCPACK we process is
266 * freshly received. */
267 netdev_drain(cli->netdev);
269 switch (cli->state) {
280 do_force_renew(cli, deadline);
284 dhclient_init(cli, 0);
289 /* Returns true if 'cli' is bound to an IP address, false otherwise. */
291 dhclient_is_bound(const struct dhclient *cli)
293 return cli->state & (S_BOUND | S_RENEWING | S_REBINDING);
296 /* Returns true if 'cli' has changed from bound to unbound, or vice versa, at
297 * least once since the last time this function was called. */
299 dhclient_changed(struct dhclient *cli)
301 bool changed = cli->changed;
306 /* Returns 'cli''s current state, as a string. The caller must not modify or
307 * free the string. */
309 dhclient_get_state(const struct dhclient *cli)
311 return state_name(cli->state);
314 /* Returns the number of seconds spent so far in 'cli''s current state. */
316 dhclient_get_state_elapsed(const struct dhclient *cli)
318 return elapsed_in_this_state(cli);
321 /* If 'cli' is bound, returns the number of seconds remaining in its lease;
322 * otherwise, returns 0. */
324 dhclient_get_lease_remaining(const struct dhclient *cli)
326 return dhclient_is_bound(cli) ? cli->lease_expiration - time_now() : 0;
329 /* If 'cli' is bound to an IP address, returns that IP address; otherwise,
332 dhclient_get_ip(const struct dhclient *cli)
334 return dhclient_is_bound(cli) ? cli->ipaddr : 0;
337 /* If 'cli' is bound to an IP address, returns the netmask for that IP address;
338 * otherwise, returns 0. */
340 dhclient_get_netmask(const struct dhclient *cli)
342 return dhclient_is_bound(cli) ? cli->netmask : 0;
345 /* If 'cli' is bound to an IP address and 'cli' has a default gateway, returns
346 * that default gateway; otherwise, returns 0. */
348 dhclient_get_router(const struct dhclient *cli)
350 return dhclient_is_bound(cli) ? cli->router : 0;
353 /* If 'cli' is bound to an IP address, returns the DHCP message that was
354 * received to obtain that IP address (so that the caller can obtain additional
355 * options from it). Otherwise, returns a null pointer. */
356 const struct dhcp_msg *
357 dhclient_get_config(const struct dhclient *cli)
359 return dhclient_is_bound(cli) ? cli->binding : NULL;
362 /* Configures the network device backing 'cli' to the network address and other
363 * parameters obtained via DHCP. If no address is bound on 'cli', removes any
364 * configured address from 'cli'.
366 * To use a dhclient as a regular DHCP client that binds and unbinds from IP
367 * addresses in the usual fashion, call this function after dhclient_run() if
368 * anything has changed, like so:
371 * if (dhclient_changed(cli)) {
372 * dhclient_configure_netdev(cli);
377 dhclient_configure_netdev(struct dhclient *cli)
379 struct in_addr addr = { dhclient_get_ip(cli) };
380 struct in_addr mask = { dhclient_get_netmask(cli) };
381 struct in_addr router = { dhclient_get_router(cli) };
384 error = netdev_set_in4(cli->netdev, addr, mask);
386 VLOG_ERR("could not set %s address "IP_FMT"/"IP_FMT": %s",
387 netdev_get_name(cli->netdev),
388 IP_ARGS(&addr.s_addr), IP_ARGS(&mask.s_addr),
392 if (!error && router.s_addr) {
393 error = netdev_add_router(cli->netdev, router);
395 VLOG_ERR("failed to add default route to "IP_FMT" on %s: %s",
396 IP_ARGS(&router), netdev_get_name(cli->netdev),
404 /* If 'cli' is bound and the binding includes DNS domain parameters, updates
405 * /etc/resolv.conf will be updated to match the received parameters. Returns
406 * 0 if successful, otherwise a positive errno value. */
408 dhclient_update_resolv_conf(struct dhclient *cli)
412 bool has_domain_name;
417 if (!dhclient_is_bound(cli)) {
420 if (!dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER, 0, &dns_server)) {
421 VLOG_DBG("binding does not include any DNS servers");
425 sprintf(new_name, "/etc/resolv.conf.tmp%ld", (long int) getpid());
426 new = fopen(new_name, "w");
428 VLOG_WARN("%s: create: %s", new_name, strerror(errno));
432 domain_name = dhcp_msg_get_string(cli->binding, DHCP_CODE_DOMAIN_NAME);
433 has_domain_name = domain_name != NULL;
435 if (strspn(domain_name, "-_.0123456789abcdefghijklmnopqrstuvwxyz"
436 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == strlen(domain_name)) {
437 fprintf(new, "domain %s\n", domain_name);
439 VLOG_WARN("ignoring invalid domain name %s", domain_name);
440 has_domain_name = false;
443 VLOG_DBG("binding does not include domain name");
447 for (i = 0; dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER,
448 i, &dns_server); i++) {
449 fprintf(new, "nameserver "IP_FMT"\n", IP_ARGS(&dns_server));
452 old = fopen("/etc/resolv.conf", "r");
456 while (fgets(line, sizeof line, old)) {
457 char *kw = xmemdup0(line, strcspn(line, " \t\r\n"));
458 if (strcmp(kw, "nameserver")
460 || (strcmp(kw, "domain") && strcmp(kw, "search")))) {
467 VLOG_DBG("/etc/resolv.conf: open: %s", strerror(errno));
470 if (fclose(new) < 0) {
471 VLOG_WARN("%s: close: %s", new_name, strerror(errno));
475 if (rename(new_name, "/etc/resolv.conf") < 0) {
476 VLOG_WARN("failed to rename %s to /etc/resolv.conf: %s",
477 new_name, strerror(errno));
487 make_dhcpdiscover(struct dhclient *cli, struct dhcp_msg *msg)
489 cli->secs = elapsed_in_this_state(cli);
490 dhclient_msg_init(cli, DHCPDISCOVER, msg);
492 dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr);
497 make_dhcprequest(struct dhclient *cli, struct dhcp_msg *msg)
499 dhclient_msg_init(cli, DHCPREQUEST, msg);
500 msg->ciaddr = dhclient_get_ip(cli);
501 if (cli->state == S_REQUESTING) {
502 dhcp_msg_put_ip(msg, DHCP_CODE_SERVER_IDENTIFIER, cli->server_ip);
504 dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr);
508 do_init(struct dhclient *cli, enum dhclient_state next_state)
510 if (!cli->init_delay) {
511 cli->init_delay = fuzz(2, 1);
513 if (timeout(cli, cli->init_delay)) {
514 state_transition(cli, next_state);
519 dhclient_run_INIT(struct dhclient *cli)
521 do_init(cli, S_SELECTING);
525 dhclient_run_INIT_REBOOT(struct dhclient *cli)
527 do_init(cli, S_REBOOTING);
531 dhclient_run_REBOOTING(struct dhclient *cli)
533 send_reliably(cli, make_dhcprequest);
534 if (!receive_ack(cli) && timeout(cli, 60)) {
535 state_transition(cli, S_INIT);
540 dhcp_receive(struct dhclient *cli, unsigned int msgs, struct dhcp_msg *msg)
542 while (do_receive_msg(cli, msg)) {
543 if (msg->type < 0 || msg->type > 31 || !((1u << msg->type) & msgs)) {
544 VLOG_DBG("received unexpected %s in %s state: %s",
545 dhcp_type_name(msg->type), state_name(cli->state),
546 dhcp_msg_to_string(msg, false, &cli->s));
547 } else if (msg->xid != cli->xid) {
548 VLOG_DBG("ignoring %s with xid != %08"PRIx32" in %s state: %s",
549 dhcp_type_name(msg->type), msg->xid,
550 state_name(cli->state),
551 dhcp_msg_to_string(msg, false, &cli->s));
555 dhcp_msg_uninit(msg);
561 validate_offered_options(struct dhclient *cli, const struct dhcp_msg *msg)
563 uint32_t lease, netmask;
564 if (!dhcp_msg_get_secs(msg, DHCP_CODE_LEASE_TIME, 0, &lease)) {
565 VLOG_WARN("%s lacks lease time: %s", dhcp_type_name(msg->type),
566 dhcp_msg_to_string(msg, false, &cli->s));
567 } else if (!dhcp_msg_get_ip(msg, DHCP_CODE_SUBNET_MASK, 0, &netmask)) {
568 VLOG_WARN("%s lacks netmask: %s", dhcp_type_name(msg->type),
569 dhcp_msg_to_string(msg, false, &cli->s));
570 } else if (lease < MIN_ACCEPTABLE_LEASE) {
571 VLOG_WARN("Ignoring %s with %"PRIu32"-second lease time: %s",
572 dhcp_type_name(msg->type), lease,
573 dhcp_msg_to_string(msg, false, &cli->s));
574 } else if (cli->validate_offer && !cli->validate_offer(msg, cli->aux)) {
575 VLOG_DBG("client validation hook refused offer: %s",
576 dhcp_msg_to_string(msg, false, &cli->s));
584 dhclient_run_SELECTING(struct dhclient *cli)
588 send_reliably(cli, make_dhcpdiscover);
589 if (cli->server_ip && timeout(cli, 60)) {
591 state_transition(cli, S_INIT);
593 for (; dhcp_receive(cli, 1u << DHCPOFFER, &msg); dhcp_msg_uninit(&msg)) {
594 if (!validate_offered_options(cli, &msg)) {
597 if (!dhcp_msg_get_ip(&msg, DHCP_CODE_SERVER_IDENTIFIER,
598 0, &cli->server_ip)) {
599 VLOG_WARN("DHCPOFFER lacks server identifier: %s",
600 dhcp_msg_to_string(&msg, false, &cli->s));
604 VLOG_DBG("accepting DHCPOFFER: %s",
605 dhcp_msg_to_string(&msg, false, &cli->s));
606 cli->ipaddr = msg.yiaddr;
607 state_transition(cli, S_REQUESTING);
613 same_binding(const struct dhcp_msg *old, const struct dhcp_msg *new)
615 static const int codes[] = {
616 DHCP_CODE_SUBNET_MASK,
618 DHCP_CODE_DNS_SERVER,
620 DHCP_CODE_DOMAIN_NAME,
623 DHCP_CODE_BROADCAST_ADDRESS,
624 DHCP_CODE_STATIC_ROUTE,
625 DHCP_CODE_ARP_CACHE_TIMEOUT,
626 DHCP_CODE_ETHERNET_ENCAPSULATION,
628 DHCP_CODE_SERVER_IDENTIFIER,
629 DHCP_CODE_OFP_CONTROLLER_VCONN,
630 DHCP_CODE_OFP_PKI_URI,
635 if (old->yiaddr != new->yiaddr) {
636 VLOG_WARN("DHCP binding changed IP address from "IP_FMT" to "IP_FMT,
637 IP_ARGS(&old->yiaddr), IP_ARGS(&new->yiaddr));
640 for (i = 0; i < ARRAY_SIZE(codes); i++) {
642 const struct dhcp_option *old_opt = &old->options[code];
643 const struct dhcp_option *new_opt = &new->options[code];
644 if (!dhcp_option_equals(old_opt, new_opt)) {
645 struct ds old_string = DS_EMPTY_INITIALIZER;
646 struct ds new_string = DS_EMPTY_INITIALIZER;
647 VLOG_WARN("DHCP binding changed option from %s to %s",
648 dhcp_option_to_string(old_opt, code, &old_string),
649 dhcp_option_to_string(new_opt, code, &new_string));
650 ds_destroy(&old_string);
651 ds_destroy(&new_string);
659 receive_ack(struct dhclient *cli)
663 if (!dhcp_receive(cli, (1u << DHCPACK) | (1u << DHCPNAK), &msg)) {
665 } else if (msg.type == DHCPNAK) {
666 dhcp_msg_uninit(&msg);
667 state_transition(cli, S_INIT);
669 } else if (!validate_offered_options(cli, &msg)) {
670 dhcp_msg_uninit(&msg);
673 uint32_t lease = 0, t1 = 0, t2 = 0;
676 if (!same_binding(cli->binding, &msg)) {
679 dhcp_msg_uninit(cli->binding);
681 cli->binding = xmalloc(sizeof *cli->binding);
683 dhcp_msg_copy(cli->binding, &msg);
685 dhcp_msg_get_secs(&msg, DHCP_CODE_LEASE_TIME, 0, &lease);
686 dhcp_msg_get_secs(&msg, DHCP_CODE_T1, 0, &t1);
687 dhcp_msg_get_secs(&msg, DHCP_CODE_T2, 0, &t2);
688 assert(lease >= MIN_ACCEPTABLE_LEASE);
690 if (!t2 || t2 >= lease) {
693 if (!t1 || t1 >= t2) {
694 t1 = calc_t1(lease, t2);
697 cli->lease_expiration = sat_add(time_now(), lease);
698 cli->bound_timeout = t1;
699 cli->renewing_timeout = t2 - t1;
700 cli->rebinding_timeout = lease - t2;
702 cli->ipaddr = msg.yiaddr;
703 dhcp_msg_get_ip(&msg, DHCP_CODE_SUBNET_MASK, 0, &cli->netmask);
704 if (!dhcp_msg_get_ip(&msg, DHCP_CODE_ROUTER, 0, &cli->router)) {
705 cli->router = INADDR_ANY;
707 state_transition(cli, S_BOUND);
708 VLOG_DBG("Bound: %s", dhcp_msg_to_string(&msg, false, &cli->s));
714 dhclient_run_REQUESTING(struct dhclient *cli)
716 send_reliably(cli, make_dhcprequest);
717 if (!receive_ack(cli) && timeout(cli, 60)) {
718 state_transition(cli, S_INIT);
723 dhclient_run_BOUND(struct dhclient *cli)
725 if (timeout(cli, cli->bound_timeout)) {
726 state_transition(cli, S_RENEWING);
731 dhclient_run_RENEWING(struct dhclient *cli)
733 send_reliably(cli, make_dhcprequest);
734 if (!receive_ack(cli) && timeout(cli, cli->renewing_timeout)) {
735 state_transition(cli, S_REBINDING);
740 dhclient_run_REBINDING(struct dhclient *cli)
742 send_reliably(cli, make_dhcprequest);
743 if (!receive_ack(cli) && timeout(cli, cli->rebinding_timeout)) {
744 state_transition(cli, S_INIT);
749 dhclient_run_RELEASED(struct dhclient *cli UNUSED)
754 /* Processes the DHCP protocol for 'cli'. */
756 dhclient_run(struct dhclient *cli)
760 old_state = cli->state;
761 cli->min_timeout = UINT_MAX;
763 switch (cli->state) {
764 #define DHCLIENT_STATE(NAME, VALUE) \
765 case S_##NAME: dhclient_run_##NAME(cli); break;
767 #undef DHCLIENT_STATE
771 } while (cli->state != old_state);
774 /* Sets up poll timeouts to wake up the poll loop when 'cli' needs to do some
777 dhclient_wait(struct dhclient *cli)
779 if (cli->min_timeout != UINT_MAX) {
780 poll_timer_wait(sat_mul(cli->min_timeout, 1000));
782 /* Reset timeout to 1 second. This will have no effect ordinarily, because
783 * dhclient_run() will typically set it back to a higher value. If,
784 * however, the caller fails to call dhclient_run() before its next call to
785 * dhclient_wait() we won't potentially block forever. */
786 cli->min_timeout = 1;
788 if (cli->state & (S_SELECTING | S_REQUESTING | S_RENEWING | S_REBINDING)) {
789 netdev_recv_wait(cli->netdev);
794 state_transition(struct dhclient *cli, enum dhclient_state state)
796 bool was_bound = dhclient_is_bound(cli);
798 if (cli->state != state) {
799 VLOG_DBG("entering %s", state_name(state));
802 cli->state_entered = time_now();
803 cli->retransmit = cli->delay = 0;
804 am_bound = dhclient_is_bound(cli);
805 if (was_bound != am_bound) {
808 assert(cli->binding != NULL);
809 VLOG_WARN("%s: obtained address "IP_FMT", netmask "IP_FMT,
810 netdev_get_name(cli->netdev),
811 IP_ARGS(&cli->ipaddr), IP_ARGS(&cli->netmask));
813 VLOG_WARN("%s: obtained default gateway "IP_FMT,
814 netdev_get_name(cli->netdev), IP_ARGS(&cli->router));
817 dhcp_msg_uninit(cli->binding);
821 VLOG_WARN("%s: network address unbound",
822 netdev_get_name(cli->netdev));
825 if (cli->state & (S_SELECTING | S_REQUESTING | S_REBOOTING)) {
826 netdev_drain(cli->netdev);
831 send_reliably(struct dhclient *cli,
832 void (*make_packet)(struct dhclient *, struct dhcp_msg *))
834 if (timeout(cli, cli->retransmit)) {
836 make_packet(cli, &msg);
837 if (cli->modify_request) {
838 cli->modify_request(&msg, cli->aux);
840 do_send_msg(cli, &msg);
841 cli->delay = MIN(64, MAX(4, cli->delay * 2));
842 cli->retransmit += fuzz(cli->delay, 1);
843 timeout(cli, cli->retransmit);
844 dhcp_msg_uninit(&msg);
849 dhclient_msg_init(struct dhclient *cli, enum dhcp_msg_type type,
850 struct dhcp_msg *msg)
853 msg->op = DHCP_BOOTREQUEST;
855 msg->secs = cli->secs;
857 memcpy(msg->chaddr, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN);
861 elapsed_in_this_state(const struct dhclient *cli)
863 return time_now() - cli->state_entered;
867 timeout(struct dhclient *cli, unsigned int secs)
869 cli->min_timeout = MIN(cli->min_timeout, secs);
870 return time_now() >= sat_add(cli->state_entered, secs);
874 do_receive_msg(struct dhclient *cli, struct dhcp_msg *msg)
878 buffer_init(&b, netdev_get_mtu(cli->netdev) + VLAN_ETH_HEADER_LEN);
879 for (; cli->received < 50; cli->received++) {
880 const struct ip_header *ip;
881 const struct dhcp_header *dhcp;
886 error = netdev_recv(cli->netdev, &b);
891 flow_extract(&b, 0, &flow);
892 if (flow.dl_type != htons(ETH_TYPE_IP)
893 || flow.nw_proto != IP_TYPE_UDP
894 || flow.tp_dst != htons(68)
895 || !(eth_addr_is_broadcast(flow.dl_dst)
896 || eth_addr_equals(flow.dl_dst,
897 netdev_get_etheraddr(cli->netdev)))) {
902 if (IP_IS_FRAGMENT(ip->ip_frag_off)) {
903 /* We don't do reassembly. */
904 VLOG_WARN("ignoring fragmented DHCP datagram");
910 VLOG_WARN("ignoring DHCP datagram with missing payload");
914 buffer_pull(&b, b.l7 - b.data);
915 error = dhcp_parse(msg, &b);
917 VLOG_DBG("received %s", dhcp_msg_to_string(msg, false, &cli->s));
922 netdev_drain(cli->netdev);
929 do_send_msg(struct dhclient *cli, const struct dhcp_msg *msg)
932 struct eth_header eh;
934 struct udp_header th;
938 buffer_init(&b, ETH_TOTAL_MAX);
939 buffer_reserve(&b, ETH_HEADER_LEN + IP_HEADER_LEN + UDP_HEADER_LEN);
941 dhcp_assemble(msg, &b);
943 memcpy(eh.eth_src, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN);
944 memcpy(eh.eth_dst, eth_addr_broadcast, ETH_ADDR_LEN);
945 eh.eth_type = htons(ETH_TYPE_IP);
947 nh.ip_ihl_ver = IP_IHL_VER(5, IP_VERSION);
949 nh.ip_tot_len = htons(IP_HEADER_LEN + UDP_HEADER_LEN + b.size);
950 /* We can't guarantee uniqueness of ip_id versus the host's, screwing up
951 * fragment reassembly, so prevent fragmentation and use an all-zeros
952 * ip_id. RFC 791 doesn't say we can do this, but Linux does the same
953 * thing for DF packets, so it must not screw anything up. */
955 nh.ip_frag_off = htons(IP_DONT_FRAGMENT);
957 nh.ip_proto = IP_TYPE_UDP;
959 nh.ip_src = dhclient_get_ip(cli);
960 /* XXX need to use UDP socket for nonzero server IPs so that we can get
961 * routing table support.
963 * if (...have server IP and in appropriate state...) {
964 * nh.ip_dst = cli->server_ip;
966 * nh.ip_dst = INADDR_BROADCAST;
969 nh.ip_dst = INADDR_BROADCAST;
970 nh.ip_csum = csum(&nh, sizeof nh);
972 th.udp_src = htons(66);
973 th.udp_dst = htons(67);
974 th.udp_len = htons(UDP_HEADER_LEN + b.size);
976 udp_csum = csum_add32(0, nh.ip_src);
977 udp_csum = csum_add32(udp_csum, nh.ip_dst);
978 udp_csum = csum_add16(udp_csum, IP_TYPE_UDP << 8);
979 udp_csum = csum_add16(udp_csum, th.udp_len);
980 udp_csum = csum_continue(udp_csum, &th, sizeof th);
981 th.udp_csum = csum_finish(csum_continue(udp_csum, b.data, b.size));
983 buffer_push(&b, &th, sizeof th);
984 buffer_push(&b, &nh, sizeof nh);
985 buffer_push(&b, &eh, sizeof eh);
987 /* Don't try to send the frame if it's too long for an Ethernet frame. We
988 * disregard the network device's actual MTU because we don't want the
989 * frame to have to be discarded or fragmented if it travels over a regular
990 * Ethernet at some point. 1500 bytes should be enough for anyone. */
991 if (b.size <= ETH_TOTAL_MAX) {
992 VLOG_DBG("sending %s", dhcp_msg_to_string(msg, false, &cli->s));
993 error = netdev_send(cli->netdev, &b);
995 VLOG_ERR("send failed on %s: %s",
996 netdev_get_name(cli->netdev), strerror(error));
999 VLOG_ERR("cannot send %zu-byte Ethernet frame", b.size);
1006 fuzz(unsigned int x, int max_fuzz)
1008 /* Generate number in range [-max_fuzz, +max_fuzz]. */
1009 int fuzz = random_range(max_fuzz * 2 + 1) - max_fuzz;
1010 unsigned int y = x + fuzz;
1011 return fuzz >= 0 ? (y >= x ? y : UINT_MAX) : (y <= x ? y : 0);
1015 clamp(unsigned int x, unsigned int min, unsigned int max)
1017 return x < min ? min : x > max ? max : x;
1021 calc_t2(unsigned int lease)
1023 unsigned int base = lease * 0.875;
1024 return lease >= 60 ? clamp(fuzz(base, 10), 0, lease - 1) : base;
1028 calc_t1(unsigned int lease, unsigned int t2)
1030 unsigned int base = lease / 2;
1031 return lease >= 60 ? clamp(fuzz(base, 10), 0, t2 - 1) : base;