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"
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,
76 state_name(enum dhclient_state state)
79 #define DHCLIENT_STATE(NAME, VALUE) case S_##NAME: return #NAME;
88 struct netdev *netdev;
90 void (*modify_request)(struct dhcp_msg *, void *aux);
91 bool (*validate_offer)(const struct dhcp_msg *, void *aux);
95 enum dhclient_state state;
96 unsigned int state_entered; /* When we transitioned to this state. */
97 uint32_t xid; /* In host byte order. */
98 uint32_t ipaddr, netmask, router;
100 struct dhcp_msg *binding;
103 unsigned int retransmit, delay; /* Used by send_reliably(). */
105 unsigned int init_delay; /* Used by S_INIT. */
107 time_t lease_expiration;
108 unsigned int bound_timeout;
109 unsigned int renewing_timeout;
110 unsigned int rebinding_timeout;
112 /* Used by dhclient_run() and dhclient_wait() */
113 unsigned int min_timeout;
116 /* Set when we send out a DHCPDISCOVER message. */
122 /* Minimum acceptable lease time, in seconds. */
123 #define MIN_ACCEPTABLE_LEASE 15
125 static void state_transition(struct dhclient *, enum dhclient_state);
126 static unsigned int elapsed_in_this_state(const struct dhclient *cli);
127 static bool timeout(struct dhclient *, unsigned int secs);
129 static void dhclient_msg_init(struct dhclient *, enum dhcp_msg_type,
131 static void send_reliably(struct dhclient *cli,
132 void (*make_packet)(struct dhclient *,
134 static bool do_receive_msg(struct dhclient *, struct dhcp_msg *);
135 static void do_send_msg(struct dhclient *, const struct dhcp_msg *);
136 static bool receive_ack(struct dhclient *);
138 static unsigned int fuzz(unsigned int x, int max_fuzz);
139 static unsigned int calc_t2(unsigned int lease);
140 static unsigned int calc_t1(unsigned int lease, unsigned int t2);
142 static unsigned int clamp(unsigned int x, unsigned int min, unsigned int max);
143 static unsigned int sat_add(unsigned int x, unsigned int y);
144 static unsigned int sat_sub(unsigned int x, unsigned int y);
145 static unsigned int sat_mul(unsigned int x, unsigned int y);
147 /* Creates a new DHCP client to configure the network device 'netdev_name'
150 * If 'modify_request' is non-null, then each DHCP message to discover or
151 * request an address will be passed to it (along with auxiliary data 'aux').
152 * It may then add any desired options to the message for transmission.
154 * If 'validate_offer' is non-null, then each DHCP message that offers an
155 * address will be passed to it (along with auxiliary data 'aux') for
156 * validation: if it returns true, the address will accepted; otherwise, it
159 * The DHCP client will not start advertising for an IP address until
160 * dhclient_init() is called.
162 * If successful, returns 0 and sets '*cli' to the new DHCP client. Otherwise,
163 * returns a positive errno value and sets '*cli' to a null pointer. */
165 dhclient_create(const char *netdev_name,
166 void (*modify_request)(struct dhcp_msg *, void *aux),
167 bool (*validate_offer)(const struct dhcp_msg *, void *aux),
168 void *aux, struct dhclient **cli_)
170 struct dhclient *cli;
171 struct netdev *netdev;
176 error = netdev_open(netdev_name, ETH_TYPE_IP, &netdev);
177 /* XXX install socket filter to catch only DHCP packets. */
179 VLOG_ERR("could not open %s network device: %s",
180 netdev_name, strerror(error));
184 error = netdev_turn_flags_on(netdev, NETDEV_UP, false);
186 VLOG_ERR("could not bring %s device up: %s",
187 netdev_name, strerror(error));
188 netdev_close(netdev);
192 cli = xcalloc(1, sizeof *cli);
193 cli->modify_request = modify_request;
194 cli->validate_offer = validate_offer;
196 cli->netdev = netdev;
197 cli->state = S_RELEASED;
198 cli->state_entered = time_now();
199 cli->xid = random_uint32();
202 cli->retransmit = cli->delay = 0;
203 cli->min_timeout = 1;
210 /* Forces 'cli' into a (re)initialization state, in which no address is bound
211 * but the client is advertising to obtain one. If 'requested_ip' is nonzero,
212 * then the client will attempt to re-bind to that IP address; otherwise, it
213 * will not ask for any particular address. */
215 dhclient_init(struct dhclient *cli, uint32_t requested_ip)
217 state_transition(cli, requested_ip ? S_INIT_REBOOT : S_INIT);
218 cli->ipaddr = requested_ip;
219 cli->min_timeout = 0;
223 /* Forces 'cli' to release its bound IP address (if any). The client will not
224 * advertise for a new address until dhclient_init() is called again. */
226 dhclient_release(struct dhclient *cli)
228 if (dhclient_is_bound(cli)) {
230 dhclient_msg_init(cli, DHCPRELEASE, &msg);
231 msg.ciaddr = cli->ipaddr;
232 do_send_msg(cli, &msg);
233 dhcp_msg_uninit(&msg);
235 state_transition(cli, S_RELEASED);
236 cli->min_timeout = UINT_MAX;
240 do_force_renew(struct dhclient *cli, int deadline)
242 time_t now = time_now();
243 unsigned int lease_left = sat_sub(cli->lease_expiration, now);
244 if (lease_left <= deadline) {
245 if (cli->state & (S_RENEWING | S_REBINDING)) {
248 deadline = lease_left;
250 if (cli->state & (S_BOUND | S_RENEWING)) {
251 state_transition(cli, S_RENEWING);
252 cli->renewing_timeout = deadline * 3 / 4;
253 cli->rebinding_timeout = deadline * 1 / 4;
255 state_transition(cli, S_REBINDING);
256 cli->rebinding_timeout = deadline;
258 cli->min_timeout = 0;
261 /* Forces 'cli' to attempt to renew the lease its current IP address (if any)
262 * within 'deadline' seconds. If the deadline is not met, then the client
263 * gives up its IP address binding and re-starts the DHCP process. */
265 dhclient_force_renew(struct dhclient *cli, int deadline)
267 /* Drain the receive queue so that we know that any DHCPACK we process is
268 * freshly received. */
269 netdev_drain(cli->netdev);
271 switch (cli->state) {
282 do_force_renew(cli, deadline);
286 dhclient_init(cli, 0);
291 /* Returns true if 'cli' is bound to an IP address, false otherwise. */
293 dhclient_is_bound(const struct dhclient *cli)
295 return cli->state & (S_BOUND | S_RENEWING | S_REBINDING);
298 /* Returns true if 'cli' has changed from bound to unbound, or vice versa, at
299 * least once since the last time this function was called. */
301 dhclient_changed(struct dhclient *cli)
303 bool changed = cli->changed;
308 /* If 'cli' is bound to an IP address, returns that IP address; otherwise,
311 dhclient_get_ip(const struct dhclient *cli)
313 return dhclient_is_bound(cli) ? cli->ipaddr : 0;
316 /* If 'cli' is bound to an IP address, returns the netmask for that IP address;
317 * otherwise, returns 0. */
319 dhclient_get_netmask(const struct dhclient *cli)
321 return dhclient_is_bound(cli) ? cli->netmask : 0;
324 /* If 'cli' is bound to an IP address and 'cli' has a default gateway, returns
325 * that default gateway; otherwise, returns 0. */
327 dhclient_get_router(const struct dhclient *cli)
329 return dhclient_is_bound(cli) ? cli->router : 0;
332 /* If 'cli' is bound to an IP address, returns the DHCP message that was
333 * received to obtain that IP address (so that the caller can obtain additional
334 * options from it). Otherwise, returns a null pointer. */
335 const struct dhcp_msg *
336 dhclient_get_config(const struct dhclient *cli)
338 return dhclient_is_bound(cli) ? cli->binding : NULL;
341 /* Configures the network device backing 'cli' to the network address and other
342 * parameters obtained via DHCP. If no address is bound on 'cli', removes any
343 * configured address from 'cli'.
345 * To use a dhclient as a regular DHCP client that binds and unbinds from IP
346 * addresses in the usual fashion, call this function after dhclient_run() if
347 * anything has changed, like so:
350 * if (dhclient_changed(cli)) {
351 * dhclient_configure_netdev(cli);
356 dhclient_configure_netdev(struct dhclient *cli)
358 struct in_addr addr = { dhclient_get_ip(cli) };
359 struct in_addr mask = { dhclient_get_netmask(cli) };
360 struct in_addr router = { dhclient_get_router(cli) };
363 error = netdev_set_in4(cli->netdev, addr, mask);
365 VLOG_ERR("could not set %s address "IP_FMT"/"IP_FMT": %s",
366 netdev_get_name(cli->netdev),
367 IP_ARGS(&addr.s_addr), IP_ARGS(&mask.s_addr),
371 if (!error && router.s_addr) {
372 error = netdev_add_router(cli->netdev, router);
374 VLOG_ERR("failed to add default route to "IP_FMT" on %s: %s",
375 IP_ARGS(&router), netdev_get_name(cli->netdev),
383 /* If 'cli' is bound and the binding includes DNS domain parameters, updates
384 * /etc/resolv.conf will be updated to match the received parameters. Returns
385 * 0 if successful, otherwise a positive errno value. */
387 dhclient_update_resolv_conf(struct dhclient *cli)
391 bool has_domain_name;
396 if (!dhclient_is_bound(cli)) {
399 if (!dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER, 0, &dns_server)) {
400 VLOG_DBG("binding does not include any DNS servers");
404 sprintf(new_name, "/etc/resolv.conf.tmp%ld", (long int) getpid());
405 new = fopen(new_name, "w");
407 VLOG_WARN("%s: create: %s", new_name, strerror(errno));
411 domain_name = dhcp_msg_get_string(cli->binding, DHCP_CODE_DOMAIN_NAME);
412 has_domain_name = domain_name != NULL;
414 if (strspn(domain_name, "-_.0123456789abcdefghijklmnopqrstuvwxyz"
415 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == strlen(domain_name)) {
416 fprintf(new, "domain %s\n", domain_name);
418 VLOG_WARN("ignoring invalid domain name %s", domain_name);
419 has_domain_name = false;
422 VLOG_DBG("binding does not include domain name");
426 for (i = 0; dhcp_msg_get_ip(cli->binding, DHCP_CODE_DNS_SERVER,
427 i, &dns_server); i++) {
428 fprintf(new, "nameserver "IP_FMT"\n", IP_ARGS(&dns_server));
431 old = fopen("/etc/resolv.conf", "r");
435 while (fgets(line, sizeof line, old)) {
436 char *kw = xmemdup0(line, strcspn(line, " \t\r\n"));
437 if (strcmp(kw, "nameserver")
439 || (strcmp(kw, "domain") && strcmp(kw, "search")))) {
446 VLOG_DBG("/etc/resolv.conf: open: %s", strerror(errno));
449 if (fclose(new) < 0) {
450 VLOG_WARN("%s: close: %s", new_name, strerror(errno));
454 if (rename(new_name, "/etc/resolv.conf") < 0) {
455 VLOG_WARN("failed to rename %s to /etc/resolv.conf: %s",
456 new_name, strerror(errno));
466 make_dhcpdiscover(struct dhclient *cli, struct dhcp_msg *msg)
468 cli->secs = elapsed_in_this_state(cli);
469 dhclient_msg_init(cli, DHCPDISCOVER, msg);
471 dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr);
476 make_dhcprequest(struct dhclient *cli, struct dhcp_msg *msg)
478 dhclient_msg_init(cli, DHCPREQUEST, msg);
479 msg->ciaddr = dhclient_get_ip(cli);
480 if (cli->state == S_REQUESTING) {
481 dhcp_msg_put_ip(msg, DHCP_CODE_SERVER_IDENTIFIER, cli->server_ip);
483 dhcp_msg_put_ip(msg, DHCP_CODE_REQUESTED_IP, cli->ipaddr);
487 do_init(struct dhclient *cli, enum dhclient_state next_state)
489 if (!cli->init_delay) {
490 cli->init_delay = clamp(fuzz(2, 8), 1, 10);
492 if (timeout(cli, cli->init_delay)) {
493 state_transition(cli, next_state);
498 dhclient_run_INIT(struct dhclient *cli)
500 do_init(cli, S_SELECTING);
504 dhclient_run_INIT_REBOOT(struct dhclient *cli)
506 do_init(cli, S_REBOOTING);
510 dhclient_run_REBOOTING(struct dhclient *cli)
512 send_reliably(cli, make_dhcprequest);
513 if (!receive_ack(cli) && timeout(cli, 60)) {
514 state_transition(cli, S_INIT);
519 dhcp_receive(struct dhclient *cli, unsigned int msgs, struct dhcp_msg *msg)
521 while (do_receive_msg(cli, msg)) {
522 if (msg->type < 0 || msg->type > 31 || !((1u << msg->type) & msgs)) {
523 VLOG_DBG("received unexpected %s in %s state: %s",
524 dhcp_type_name(msg->type), state_name(cli->state),
525 dhcp_msg_to_string(msg, false, &cli->s));
526 } else if (msg->xid != cli->xid) {
527 VLOG_DBG("ignoring %s with xid != %08"PRIx32" in %s state: %s",
528 dhcp_type_name(msg->type), msg->xid,
529 state_name(cli->state),
530 dhcp_msg_to_string(msg, false, &cli->s));
534 dhcp_msg_uninit(msg);
540 validate_offered_options(struct dhclient *cli, const struct dhcp_msg *msg)
542 uint32_t lease, netmask;
543 if (!dhcp_msg_get_secs(msg, DHCP_CODE_LEASE_TIME, 0, &lease)) {
544 VLOG_WARN("%s lacks lease time: %s", dhcp_type_name(msg->type),
545 dhcp_msg_to_string(msg, false, &cli->s));
546 } else if (!dhcp_msg_get_ip(msg, DHCP_CODE_SUBNET_MASK, 0, &netmask)) {
547 VLOG_WARN("%s lacks netmask: %s", dhcp_type_name(msg->type),
548 dhcp_msg_to_string(msg, false, &cli->s));
549 } else if (lease < MIN_ACCEPTABLE_LEASE) {
550 VLOG_WARN("Ignoring %s with %"PRIu32"-second lease time: %s",
551 dhcp_type_name(msg->type), lease,
552 dhcp_msg_to_string(msg, false, &cli->s));
553 } else if (cli->validate_offer && !cli->validate_offer(msg, cli->aux)) {
554 VLOG_DBG("client validation hook refused offer: %s",
555 dhcp_msg_to_string(msg, false, &cli->s));
563 dhclient_run_SELECTING(struct dhclient *cli)
567 send_reliably(cli, make_dhcpdiscover);
568 if (cli->server_ip && timeout(cli, 60)) {
570 state_transition(cli, S_INIT);
572 for (; dhcp_receive(cli, 1u << DHCPOFFER, &msg); dhcp_msg_uninit(&msg)) {
573 if (!validate_offered_options(cli, &msg)) {
576 if (!dhcp_msg_get_ip(&msg, DHCP_CODE_SERVER_IDENTIFIER,
577 0, &cli->server_ip)) {
578 VLOG_WARN("DHCPOFFER lacks server identifier: %s",
579 dhcp_msg_to_string(&msg, false, &cli->s));
583 VLOG_DBG("accepting DHCPOFFER: %s",
584 dhcp_msg_to_string(&msg, false, &cli->s));
585 cli->ipaddr = msg.yiaddr;
586 state_transition(cli, S_REQUESTING);
592 same_binding(const struct dhcp_msg *old, const struct dhcp_msg *new)
594 static const int codes[] = {
595 DHCP_CODE_SUBNET_MASK,
597 DHCP_CODE_DNS_SERVER,
599 DHCP_CODE_DOMAIN_NAME,
602 DHCP_CODE_BROADCAST_ADDRESS,
603 DHCP_CODE_STATIC_ROUTE,
604 DHCP_CODE_ARP_CACHE_TIMEOUT,
605 DHCP_CODE_ETHERNET_ENCAPSULATION,
607 DHCP_CODE_SERVER_IDENTIFIER,
608 DHCP_CODE_OFP_CONTROLLER_VCONN,
609 DHCP_CODE_OFP_PKI_URI,
614 if (old->yiaddr != new->yiaddr) {
615 VLOG_WARN("DHCP binding changed IP address from "IP_FMT" to "IP_FMT,
616 IP_ARGS(&old->yiaddr), IP_ARGS(&new->yiaddr));
619 for (i = 0; i < ARRAY_SIZE(codes); i++) {
621 const struct dhcp_option *old_opt = &old->options[code];
622 const struct dhcp_option *new_opt = &new->options[code];
623 if (!dhcp_option_equals(old_opt, new_opt)) {
624 struct ds old_string = DS_EMPTY_INITIALIZER;
625 struct ds new_string = DS_EMPTY_INITIALIZER;
626 VLOG_WARN("DHCP binding changed option from %s to %s",
627 dhcp_option_to_string(old_opt, code, &old_string),
628 dhcp_option_to_string(new_opt, code, &new_string));
629 ds_destroy(&old_string);
630 ds_destroy(&new_string);
638 receive_ack(struct dhclient *cli)
642 if (!dhcp_receive(cli, (1u << DHCPACK) | (1u << DHCPNAK), &msg)) {
644 } else if (msg.type == DHCPNAK) {
645 dhcp_msg_uninit(&msg);
646 state_transition(cli, S_INIT);
648 } else if (!validate_offered_options(cli, &msg)) {
649 dhcp_msg_uninit(&msg);
652 uint32_t lease = 0, t1 = 0, t2 = 0;
655 if (!same_binding(cli->binding, &msg)) {
658 dhcp_msg_uninit(cli->binding);
660 cli->binding = xmalloc(sizeof *cli->binding);
662 dhcp_msg_copy(cli->binding, &msg);
664 dhcp_msg_get_secs(&msg, DHCP_CODE_LEASE_TIME, 0, &lease);
665 dhcp_msg_get_secs(&msg, DHCP_CODE_T1, 0, &t1);
666 dhcp_msg_get_secs(&msg, DHCP_CODE_T2, 0, &t2);
667 assert(lease >= MIN_ACCEPTABLE_LEASE);
669 if (!t2 || t2 >= lease) {
672 if (!t1 || t1 >= t2) {
673 t1 = calc_t1(lease, t2);
676 cli->lease_expiration = sat_add(time_now(), lease);
677 cli->bound_timeout = t1;
678 cli->renewing_timeout = t2 - t1;
679 cli->rebinding_timeout = lease - t2;
681 cli->ipaddr = msg.yiaddr;
682 dhcp_msg_get_ip(&msg, DHCP_CODE_SUBNET_MASK, 0, &cli->netmask);
683 if (!dhcp_msg_get_ip(&msg, DHCP_CODE_ROUTER, 0, &cli->router)) {
684 cli->router = INADDR_ANY;
686 state_transition(cli, S_BOUND);
687 VLOG_DBG("Bound: %s", dhcp_msg_to_string(&msg, false, &cli->s));
693 dhclient_run_REQUESTING(struct dhclient *cli)
695 send_reliably(cli, make_dhcprequest);
696 if (!receive_ack(cli) && timeout(cli, 60)) {
697 state_transition(cli, S_INIT);
702 dhclient_run_BOUND(struct dhclient *cli)
704 if (timeout(cli, cli->bound_timeout)) {
705 state_transition(cli, S_RENEWING);
710 dhclient_run_RENEWING(struct dhclient *cli)
712 send_reliably(cli, make_dhcprequest);
713 if (!receive_ack(cli) && timeout(cli, cli->renewing_timeout)) {
714 state_transition(cli, S_REBINDING);
719 dhclient_run_REBINDING(struct dhclient *cli)
721 send_reliably(cli, make_dhcprequest);
722 if (!receive_ack(cli) && timeout(cli, cli->rebinding_timeout)) {
723 state_transition(cli, S_INIT);
728 dhclient_run_RELEASED(struct dhclient *cli UNUSED)
733 /* Processes the DHCP protocol for 'cli'. */
735 dhclient_run(struct dhclient *cli)
739 old_state = cli->state;
740 cli->min_timeout = UINT_MAX;
742 switch (cli->state) {
743 #define DHCLIENT_STATE(NAME, VALUE) \
744 case S_##NAME: dhclient_run_##NAME(cli); break;
746 #undef DHCLIENT_STATE
750 } while (cli->state != old_state);
753 /* Sets up poll timeouts to wake up the poll loop when 'cli' needs to do some
756 dhclient_wait(struct dhclient *cli)
758 if (cli->min_timeout != UINT_MAX) {
759 poll_timer_wait(sat_mul(cli->min_timeout, 1000));
761 /* Reset timeout to 1 second. This will have no effect ordinarily, because
762 * dhclient_run() will typically set it back to a higher value. If,
763 * however, the caller fails to call dhclient_run() before its next call to
764 * dhclient_wait() we won't potentially block forever. */
765 cli->min_timeout = 1;
767 if (cli->state & (S_SELECTING | S_REQUESTING | S_RENEWING | S_REBINDING)) {
768 netdev_recv_wait(cli->netdev);
773 state_transition(struct dhclient *cli, enum dhclient_state state)
775 bool was_bound = dhclient_is_bound(cli);
777 if (cli->state != state) {
778 VLOG_DBG("entering %s", state_name(state));
781 cli->state_entered = time_now();
782 cli->retransmit = cli->delay = 0;
783 am_bound = dhclient_is_bound(cli);
784 if (was_bound != am_bound) {
787 assert(cli->binding != NULL);
788 VLOG_WARN("%s: obtained address "IP_FMT", netmask "IP_FMT,
789 netdev_get_name(cli->netdev),
790 IP_ARGS(&cli->ipaddr), IP_ARGS(&cli->netmask));
792 VLOG_WARN("%s: obtained default gateway "IP_FMT,
793 netdev_get_name(cli->netdev), IP_ARGS(&cli->router));
796 dhcp_msg_uninit(cli->binding);
800 VLOG_WARN("%s: network address unbound",
801 netdev_get_name(cli->netdev));
804 if (cli->state & (S_SELECTING | S_REQUESTING | S_REBOOTING)) {
805 netdev_drain(cli->netdev);
810 send_reliably(struct dhclient *cli,
811 void (*make_packet)(struct dhclient *, struct dhcp_msg *))
813 if (timeout(cli, cli->retransmit)) {
815 make_packet(cli, &msg);
816 if (cli->modify_request) {
817 cli->modify_request(&msg, cli->aux);
819 do_send_msg(cli, &msg);
820 cli->delay = MIN(64, MAX(4, cli->delay * 2));
821 cli->retransmit += fuzz(cli->delay, 1);
822 timeout(cli, cli->retransmit);
823 dhcp_msg_uninit(&msg);
828 dhclient_msg_init(struct dhclient *cli, enum dhcp_msg_type type,
829 struct dhcp_msg *msg)
832 msg->op = DHCP_BOOTREQUEST;
834 msg->secs = cli->secs;
836 memcpy(msg->chaddr, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN);
840 elapsed_in_this_state(const struct dhclient *cli)
842 return time_now() - cli->state_entered;
846 timeout(struct dhclient *cli, unsigned int secs)
848 cli->min_timeout = MIN(cli->min_timeout, secs);
849 return time_now() >= sat_add(cli->state_entered, secs);
853 do_receive_msg(struct dhclient *cli, struct dhcp_msg *msg)
857 buffer_init(&b, netdev_get_mtu(cli->netdev) + VLAN_ETH_HEADER_LEN);
858 for (; cli->received < 50; cli->received++) {
859 const struct ip_header *ip;
860 const struct dhcp_header *dhcp;
865 error = netdev_recv(cli->netdev, &b);
870 flow_extract(&b, 0, &flow);
871 if (flow.dl_type != htons(ETH_TYPE_IP)
872 || flow.nw_proto != IP_TYPE_UDP
873 || flow.tp_dst != htons(68)
874 || !(eth_addr_is_broadcast(flow.dl_dst)
875 || eth_addr_equals(flow.dl_dst,
876 netdev_get_etheraddr(cli->netdev)))) {
881 if (IP_IS_FRAGMENT(ip->ip_frag_off)) {
882 /* We don't do reassembly. */
883 VLOG_WARN("ignoring fragmented DHCP datagram");
889 VLOG_WARN("ignoring DHCP datagram with missing payload");
893 buffer_pull(&b, b.l7 - b.data);
894 error = dhcp_parse(msg, &b);
896 VLOG_DBG("received %s", dhcp_msg_to_string(msg, false, &cli->s));
901 netdev_drain(cli->netdev);
908 do_send_msg(struct dhclient *cli, const struct dhcp_msg *msg)
911 struct eth_header eh;
913 struct udp_header th;
917 buffer_init(&b, ETH_TOTAL_MAX);
918 buffer_reserve(&b, ETH_HEADER_LEN + IP_HEADER_LEN + UDP_HEADER_LEN);
920 dhcp_assemble(msg, &b);
922 memcpy(eh.eth_src, netdev_get_etheraddr(cli->netdev), ETH_ADDR_LEN);
923 memcpy(eh.eth_dst, eth_addr_broadcast, ETH_ADDR_LEN);
924 eh.eth_type = htons(ETH_TYPE_IP);
926 nh.ip_ihl_ver = IP_IHL_VER(5, IP_VERSION);
928 nh.ip_tot_len = htons(IP_HEADER_LEN + UDP_HEADER_LEN + b.size);
929 /* We can't guarantee uniqueness of ip_id versus the host's, screwing up
930 * fragment reassembly, so prevent fragmentation and use an all-zeros
931 * ip_id. RFC 791 doesn't say we can do this, but Linux does the same
932 * thing for DF packets, so it must not screw anything up. */
934 nh.ip_frag_off = htons(IP_DONT_FRAGMENT);
936 nh.ip_proto = IP_TYPE_UDP;
938 nh.ip_src = dhclient_get_ip(cli);
939 /* XXX need to use UDP socket for nonzero server IPs so that we can get
940 * routing table support.
942 * if (...have server IP and in appropriate state...) {
943 * nh.ip_dst = cli->server_ip;
945 * nh.ip_dst = INADDR_BROADCAST;
948 nh.ip_dst = INADDR_BROADCAST;
949 nh.ip_csum = csum(&nh, sizeof nh);
951 th.udp_src = htons(66);
952 th.udp_dst = htons(67);
953 th.udp_len = htons(UDP_HEADER_LEN + b.size);
955 udp_csum = csum_add32(0, nh.ip_src);
956 udp_csum = csum_add32(udp_csum, nh.ip_dst);
957 udp_csum = csum_add16(udp_csum, IP_TYPE_UDP << 8);
958 udp_csum = csum_add16(udp_csum, th.udp_len);
959 udp_csum = csum_continue(udp_csum, &th, sizeof th);
960 th.udp_csum = csum_finish(csum_continue(udp_csum, b.data, b.size));
962 buffer_push(&b, &th, sizeof th);
963 buffer_push(&b, &nh, sizeof nh);
964 buffer_push(&b, &eh, sizeof eh);
966 /* Don't try to send the frame if it's too long for an Ethernet frame. We
967 * disregard the network device's actual MTU because we don't want the
968 * frame to have to be discarded or fragmented if it travels over a regular
969 * Ethernet at some point. 1500 bytes should be enough for anyone. */
970 if (b.size <= ETH_TOTAL_MAX) {
971 VLOG_DBG("sending %s", dhcp_msg_to_string(msg, false, &cli->s));
972 error = netdev_send(cli->netdev, &b);
974 VLOG_ERR("send failed on %s: %s",
975 netdev_get_name(cli->netdev), strerror(error));
978 VLOG_ERR("cannot send %zu-byte Ethernet frame", b.size);
985 fuzz(unsigned int x, int max_fuzz)
987 /* Generate number in range [-max_fuzz, +max_fuzz]. */
988 int fuzz = random_range(max_fuzz * 2 + 1) - max_fuzz;
989 unsigned int y = x + fuzz;
990 return fuzz >= 0 ? (y >= x ? y : UINT_MAX) : (y <= x ? y : 0);
994 sat_add(unsigned int x, unsigned int y)
996 return x + y >= x ? x + y : UINT_MAX;
1000 sat_sub(unsigned int x, unsigned int y)
1002 return x >= y ? x - y : 0;
1006 sat_mul(unsigned int x, unsigned int y)
1009 return x <= UINT_MAX / y ? x * y : UINT_MAX;
1013 clamp(unsigned int x, unsigned int min, unsigned int max)
1015 return x < min ? min : x > max ? max : x;
1019 calc_t2(unsigned int lease)
1021 unsigned int base = lease * 0.875;
1022 return lease >= 60 ? clamp(fuzz(base, 10), 0, lease - 1) : base;
1026 calc_t1(unsigned int lease, unsigned int t2)
1028 unsigned int base = lease / 2;
1029 return lease >= 60 ? clamp(fuzz(base, 10), 0, t2 - 1) : base;