2 * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
3 * Copyright (C) 2016 Hans Dedecker <dedeckeh@gmail.com>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License v2 as published by
7 * the Free Software Foundation.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
26 #include <net/if_arp.h>
27 #include <netinet/ip.h>
28 #include <sys/ioctl.h>
29 #include <sys/timerfd.h>
30 #include <arpa/inet.h>
32 #include <libubox/md5.h>
38 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info);
39 static int setup_dhcpv4_addresses(struct interface *iface);
40 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr);
41 static void valid_until_cb(struct uloop_timeout *event);
42 static void handle_addrlist_change(struct interface *iface);
43 static void dhcpv4_fr_start(struct dhcp_assignment *a);
44 static void dhcpv4_fr_rand_delay(struct dhcp_assignment *a);
45 static void dhcpv4_fr_stop(struct dhcp_assignment *a);
46 static void handle_dhcpv4(void *addr, void *data, size_t len,
47 struct interface *iface, void *dest_addr);
48 static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
49 enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr,
50 uint32_t *leasetime, const char *hostname, const size_t hostname_len,
51 const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid);
53 static struct netevent_handler dhcpv4_netevent_handler = { .cb = dhcpv4_netevent_cb, };
54 static struct uloop_timeout valid_until_timeout = {.cb = valid_until_cb};
55 static uint32_t serial = 0;
57 struct odhcpd_ref_ip {
58 struct list_head head;
60 struct odhcpd_ipaddr addr;
63 /* Create socket and register events */
66 uloop_timeout_set(&valid_until_timeout, 1000);
67 netlink_add_netevent_handler(&dhcpv4_netevent_handler);
72 int dhcpv4_setup_interface(struct interface *iface, bool enable)
76 if (iface->dhcpv4_event.uloop.fd > 0) {
77 uloop_fd_delete(&iface->dhcpv4_event.uloop);
78 close(iface->dhcpv4_event.uloop.fd);
79 iface->dhcpv4_event.uloop.fd = -1;
82 if (iface->dhcpv4 && enable) {
83 struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT),
87 if (!iface->dhcpv4_assignments.next)
88 INIT_LIST_HEAD(&iface->dhcpv4_assignments);
90 if (!iface->dhcpv4_fr_ips.next)
91 INIT_LIST_HEAD(&iface->dhcpv4_fr_ips);
93 iface->dhcpv4_event.uloop.fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
94 if (iface->dhcpv4_event.uloop.fd < 0) {
95 syslog(LOG_ERR, "socket(AF_INET): %m");
100 /* Basic IPv4 configuration */
101 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_REUSEADDR,
102 &val, sizeof(val)) < 0) {
103 syslog(LOG_ERR, "setsockopt(SO_REUSEADDR): %m");
108 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BROADCAST,
109 &val, sizeof(val)) < 0) {
110 syslog(LOG_ERR, "setsockopt(SO_BROADCAST): %m");
115 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_PKTINFO,
116 &val, sizeof(val)) < 0) {
117 syslog(LOG_ERR, "setsockopt(IP_PKTINFO): %m");
122 val = IPTOS_PREC_INTERNETCONTROL;
123 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_TOS,
124 &val, sizeof(val)) < 0) {
125 syslog(LOG_ERR, "setsockopt(IP_TOS): %m");
130 val = IP_PMTUDISC_DONT;
131 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_MTU_DISCOVER,
132 &val, sizeof(val)) < 0) {
133 syslog(LOG_ERR, "setsockopt(IP_MTU_DISCOVER): %m");
138 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE,
139 iface->ifname, strlen(iface->ifname)) < 0) {
140 syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m");
145 if (bind(iface->dhcpv4_event.uloop.fd, (struct sockaddr*)&bind_addr,
146 sizeof(bind_addr)) < 0) {
147 syslog(LOG_ERR, "bind(): %m");
152 if (setup_dhcpv4_addresses(iface) < 0) {
157 iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
158 odhcpd_register(&iface->dhcpv4_event);
159 } else if (iface->dhcpv4_assignments.next) {
160 while (!list_empty(&iface->dhcpv4_assignments))
161 free_assignment(list_first_entry(&iface->dhcpv4_assignments,
162 struct dhcp_assignment, head));
166 if (ret < 0 && iface->dhcpv4_event.uloop.fd > 0) {
167 close(iface->dhcpv4_event.uloop.fd);
168 iface->dhcpv4_event.uloop.fd = -1;
175 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info)
177 struct interface *iface = info->iface;
179 if (!iface || iface->dhcpv4 == MODE_DISABLED)
183 case NETEV_IFINDEX_CHANGE:
184 dhcpv4_setup_interface(iface, true);
186 case NETEV_ADDRLIST_CHANGE:
187 handle_addrlist_change(iface);
194 static struct dhcp_assignment *find_assignment_by_hwaddr(struct interface *iface, const uint8_t *hwaddr)
196 struct dhcp_assignment *a;
198 list_for_each_entry(a, &iface->dhcpv4_assignments, head)
199 if (!memcmp(a->hwaddr, hwaddr, 6))
205 static int setup_dhcpv4_addresses(struct interface *iface)
207 iface->dhcpv4_start_ip.s_addr = INADDR_ANY;
208 iface->dhcpv4_end_ip.s_addr = INADDR_ANY;
209 iface->dhcpv4_local.s_addr = INADDR_ANY;
210 iface->dhcpv4_bcast.s_addr = INADDR_ANY;
211 iface->dhcpv4_mask.s_addr = INADDR_ANY;
214 if (iface->dhcpv4_start.s_addr & htonl(0xffff0000) ||
215 iface->dhcpv4_end.s_addr & htonl(0xffff0000) ||
216 ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) {
217 syslog(LOG_ERR, "Invalid DHCP range for %s", iface->name);
221 if (!iface->addr4_len) {
222 syslog(LOG_WARNING, "No network(s) available on %s", iface->name);
226 uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
227 uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
229 for (size_t i = 0; i < iface->addr4_len && start && end; i++) {
230 struct in_addr *addr = &iface->addr4[i].addr.in;
233 if (addr_is_fr_ip(iface, addr))
236 odhcpd_bitlen2netmask(false, iface->addr4[i].prefix, &mask);
237 if ((start & ntohl(~mask.s_addr)) == start &&
238 (end & ntohl(~mask.s_addr)) == end) {
239 iface->dhcpv4_start_ip.s_addr = htonl(start) |
240 (addr->s_addr & mask.s_addr);
241 iface->dhcpv4_end_ip.s_addr = htonl(end) |
242 (addr->s_addr & mask.s_addr);
243 iface->dhcpv4_local = *addr;
244 iface->dhcpv4_bcast = iface->addr4[i].broadcast;
245 iface->dhcpv4_mask = mask;
250 /* Don't allocate IP range for subnets bigger than 28 */
251 if (iface->addr4[0].prefix > 28) {
252 syslog(LOG_WARNING, "Auto allocation of DHCP range fails on %s", iface->name);
256 iface->dhcpv4_local = iface->addr4[0].addr.in;
257 iface->dhcpv4_bcast = iface->addr4[0].broadcast;
258 odhcpd_bitlen2netmask(false, iface->addr4[0].prefix, &iface->dhcpv4_mask);
259 end = start = iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr;
261 /* Auto allocate ranges */
262 if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffff00) {
263 iface->dhcpv4_start_ip.s_addr = start | htonl(100);
264 iface->dhcpv4_end_ip.s_addr = end | htonl(250);
265 } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffc0) {
266 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
267 iface->dhcpv4_end_ip.s_addr = end | htonl(60);
268 } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffe0) {
269 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
270 iface->dhcpv4_end_ip.s_addr = end | htonl(30);
272 iface->dhcpv4_start_ip.s_addr = start | htonl(3);
273 iface->dhcpv4_end_ip.s_addr = end | htonl(12);
279 static void inc_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct odhcpd_ref_ip *ip)
285 static void decr_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct interface *iface)
287 struct odhcpd_ref_ip *ip = *ptr;
289 if (--ip->ref_cnt == 0) {
290 netlink_setup_addr(&ip->addr, iface->ifindex, false, false);
299 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr)
301 struct odhcpd_ref_ip *p;
303 list_for_each_entry(p, &iface->dhcpv4_fr_ips, head) {
304 if (addr->s_addr == p->addr.addr.in.s_addr)
311 static bool leases_require_fr(struct interface *iface, struct odhcpd_ipaddr *addr,
314 struct dhcp_assignment *a = NULL;
315 struct odhcpd_ref_ip *fr_ip = NULL;
317 list_for_each_entry(a, &iface->dhcpv4_assignments, head) {
318 if ((a->accept_fr_nonce || iface->dhcpv4_forcereconf) &&
320 ((a->addr & mask) == (addr->addr.in.s_addr & mask))) {
322 fr_ip = calloc(1, sizeof(*fr_ip));
326 list_add(&fr_ip->head, &iface->dhcpv4_fr_ips);
329 inc_ref_cnt_ip(&a->fr_ip, fr_ip);
333 return fr_ip ? true : false;
336 static void valid_until_cb(struct uloop_timeout *event)
338 struct interface *iface;
339 time_t now = odhcpd_time();
341 avl_for_each_element(&interfaces, iface, avl) {
342 if (iface->dhcpv4 != MODE_SERVER || iface->dhcpv4_assignments.next == NULL)
345 struct dhcp_assignment *a, *n;
346 list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
347 if (!INFINITE_VALID(a->valid_until) && a->valid_until < now)
351 uloop_timeout_set(event, 1000);
354 static void handle_addrlist_change(struct interface *iface)
356 struct odhcpd_ipaddr ip;
357 struct odhcpd_ref_ip *a;
358 struct dhcp_assignment *c;
359 uint32_t mask = iface->dhcpv4_mask.s_addr;
361 memset(&ip, 0, sizeof(ip));
362 ip.addr.in = iface->dhcpv4_local;
363 ip.prefix = odhcpd_netmask2bitlen(false, &iface->dhcpv4_mask);
364 ip.broadcast = iface->dhcpv4_bcast;
366 setup_dhcpv4_addresses(iface);
368 if ((ip.addr.in.s_addr & mask) ==
369 (iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr))
372 if (ip.addr.in.s_addr && !leases_require_fr(iface, &ip, mask))
375 if (iface->dhcpv4_local.s_addr == INADDR_ANY || list_empty(&iface->dhcpv4_fr_ips))
378 a = list_first_entry(&iface->dhcpv4_fr_ips, struct odhcpd_ref_ip, head);
380 if (netlink_setup_addr(&a->addr, iface->ifindex, false, true)) {
381 syslog(LOG_ERR, "Failed to add ip address on %s", iface->name);
385 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
386 if ((c->flags & OAF_BOUND) && c->fr_ip && !c->fr_cnt) {
387 if (c->accept_fr_nonce || iface->dhcpv4_forcereconf)
388 dhcpv4_fr_rand_delay(c);
395 static char *dhcpv4_msg_to_string(uint8_t reqmsg)
398 case (DHCPV4_MSG_DISCOVER):
399 return "DHCPV4_MSG_DISCOVER";
400 case (DHCPV4_MSG_OFFER):
401 return "DHCPV4_MSG_OFFER";
402 case (DHCPV4_MSG_REQUEST):
403 return "DHCPV4_MSG_REQUEST";
404 case (DHCPV4_MSG_DECLINE):
405 return "DHCPV4_MSG_DECLINE";
406 case (DHCPV4_MSG_ACK):
407 return "DHCPV4_MSG_ACK";
408 case (DHCPV4_MSG_NAK):
409 return "DHCPV4_MSG_NAK";
410 case (DHCPV4_MSG_RELEASE):
411 return "DHCPV4_MSG_RELEASE";
412 case (DHCPV4_MSG_INFORM):
413 return "DHCPV4_MSG_INFORM";
414 case (DHCPV4_MSG_FORCERENEW):
415 return "DHCPV4_MSG_FORCERENEW";
421 static void dhcpv4_free_assignment(struct dhcp_assignment *a)
427 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
428 uint8_t type, uint8_t len, const void *data)
430 uint8_t *c = *cookie;
431 uint8_t *end = (uint8_t *)msg + sizeof(*msg);
433 if (*cookie + 2 + len > end)
438 memcpy(c, data, len);
443 static void dhcpv4_fr_send(struct dhcp_assignment *a)
445 struct dhcpv4_message fr_msg = {
446 .op = DHCPV4_BOOTREPLY,
452 .ciaddr = {INADDR_ANY},
453 .yiaddr = {INADDR_ANY},
454 .siaddr = {INADDR_ANY},
455 .giaddr = {INADDR_ANY},
460 struct dhcpv4_auth_forcerenew *auth_o, auth = {
464 .replay = {htonl(time(NULL)), htonl(++serial)},
468 struct interface *iface = a->iface;
470 odhcpd_urandom(&fr_msg.xid, sizeof(fr_msg.xid));
471 memcpy(fr_msg.chaddr, a->hwaddr, fr_msg.hlen);
473 fr_msg.options[0] = 0x63;
474 fr_msg.options[1] = 0x82;
475 fr_msg.options[2] = 0x53;
476 fr_msg.options[3] = 0x63;
478 uint8_t *cookie = &fr_msg.options[4];
479 uint8_t msg = DHCPV4_MSG_FORCERENEW;
481 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
482 if (a->accept_fr_nonce) {
483 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
484 auth_o = (struct dhcpv4_auth_forcerenew *)(cookie - sizeof(auth));
485 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
488 uint8_t secretbytes[64];
489 memset(secretbytes, 0, sizeof(secretbytes));
490 memcpy(secretbytes, a->key, sizeof(a->key));
492 for (size_t i = 0; i < sizeof(secretbytes); ++i)
493 secretbytes[i] ^= 0x36;
496 md5_hash(secretbytes, sizeof(secretbytes), &md5);
497 md5_hash(&fr_msg, sizeof(fr_msg), &md5);
498 md5_end(auth_o->key, &md5);
500 for (size_t i = 0; i < sizeof(secretbytes); ++i) {
501 secretbytes[i] ^= 0x36;
502 secretbytes[i] ^= 0x5c;
506 md5_hash(secretbytes, sizeof(secretbytes), &md5);
507 md5_hash(auth_o->key, sizeof(auth_o->key), &md5);
508 md5_end(auth_o->key, &md5);
510 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_SERVERID, 4,
511 &a->fr_ip->addr.addr.in.s_addr);
512 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
515 struct sockaddr_in dest;
516 memset(&dest, 0, sizeof(dest));
517 dest.sin_family = AF_INET;
518 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
519 dest.sin_addr.s_addr = a->addr;
521 if (sendto(iface->dhcpv4_event.uloop.fd, &fr_msg, sizeof(fr_msg),
522 MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest)) < 0)
523 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m", dhcpv4_msg_to_string(msg),
524 odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
526 syslog(LOG_WARNING, "Sent %s to %s - %s", dhcpv4_msg_to_string(msg),
527 odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
530 static void dhcpv4_fr_timer(struct uloop_timeout *event)
532 struct dhcp_assignment *a = container_of(event, struct dhcp_assignment, fr_timer);
534 if (a->fr_cnt > 0 && a->fr_cnt < 8) {
536 uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
542 static void dhcpv4_fr_start(struct dhcp_assignment *a)
544 uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
545 a->fr_timer.cb = dhcpv4_fr_timer;
551 static void dhcpv4_fr_delay_timer(struct uloop_timeout *event)
553 struct dhcp_assignment *a = container_of(event, struct dhcp_assignment, fr_timer);
554 struct interface *iface = a->iface;
556 (iface->dhcpv4_event.uloop.fd == -1 ? dhcpv4_fr_rand_delay(a) : dhcpv4_fr_start(a));
559 static void dhcpv4_fr_rand_delay(struct dhcp_assignment *a)
561 #define MIN_DELAY 500
565 odhcpd_urandom(&msecs, sizeof(msecs));
567 msecs = labs(msecs)%MAX_FUZZ + MIN_DELAY;
569 uloop_timeout_set(&a->fr_timer, msecs);
570 a->fr_timer.cb = dhcpv4_fr_delay_timer;
573 static void dhcpv4_fr_stop(struct dhcp_assignment *a)
575 uloop_timeout_cancel(&a->fr_timer);
576 decr_ref_cnt_ip(&a->fr_ip, a->iface);
578 a->fr_timer.cb = NULL;
581 /* Handler for DHCPv4 messages */
582 static void handle_dhcpv4(void *addr, void *data, size_t len,
583 struct interface *iface, _unused void *dest_addr)
585 struct dhcpv4_message *req = data;
590 if (len < offsetof(struct dhcpv4_message, options) + 4 ||
591 req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
594 syslog(LOG_NOTICE, "Got DHCPv4 request on %s", iface->name);
596 if (!iface->dhcpv4_start_ip.s_addr && !iface->dhcpv4_end_ip.s_addr) {
597 syslog(LOG_WARNING, "No DHCP range available on %s", iface->name);
601 int sock = iface->dhcpv4_event.uloop.fd;
603 struct dhcpv4_message reply = {
604 .op = DHCPV4_BOOTREPLY,
611 .ciaddr = {INADDR_ANY},
612 .giaddr = req->giaddr,
613 .siaddr = iface->dhcpv4_local,
615 memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr));
617 reply.options[0] = 0x63;
618 reply.options[1] = 0x82;
619 reply.options[2] = 0x53;
620 reply.options[3] = 0x63;
622 uint8_t *cookie = &reply.options[4];
623 uint8_t reqmsg = DHCPV4_MSG_REQUEST;
624 uint8_t msg = DHCPV4_MSG_ACK;
626 uint32_t reqaddr = INADDR_ANY;
627 uint32_t leasetime = 0;
628 size_t hostname_len = 0;
630 bool accept_fr_nonce = false;
631 bool incl_fr_opt = false;
633 uint8_t *start = &req->options[4];
634 uint8_t *end = ((uint8_t*)data) + len;
635 struct dhcpv4_option *opt;
636 dhcpv4_for_each_option(start, end, opt) {
637 if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1)
638 reqmsg = opt->data[0];
639 else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
640 hostname_len = opt->len;
641 memcpy(hostname, opt->data, hostname_len);
642 hostname[hostname_len] = 0;
643 } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4)
644 memcpy(&reqaddr, opt->data, 4);
645 else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
646 if (memcmp(opt->data, &iface->dhcpv4_local, 4))
648 } else if (iface->filter_class && opt->type == DHCPV4_OPT_USER_CLASS) {
649 uint8_t *c = opt->data, *cend = &opt->data[opt->len];
650 for (; c < cend && &c[*c] < cend; c = &c[1 + *c]) {
651 size_t elen = strlen(iface->filter_class);
652 if (*c == elen && !memcmp(&c[1], iface->filter_class, elen))
653 return; // Ignore from homenet
655 } else if (opt->type == DHCPV4_OPT_LEASETIME && opt->len == 4)
656 memcpy(&leasetime, opt->data, 4);
657 else if (opt->type == DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE && opt->len > 0) {
658 for (uint8_t i = 0; i < opt->len; i++) {
659 if (opt->data[i] == 1) {
660 accept_fr_nonce = true;
668 if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
669 reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
670 reqmsg != DHCPV4_MSG_RELEASE)
673 struct dhcp_assignment *a = NULL;
674 uint32_t serverid = iface->dhcpv4_local.s_addr;
675 uint32_t fr_serverid = INADDR_ANY;
677 if (reqmsg != DHCPV4_MSG_INFORM)
678 a = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr,
679 &leasetime, hostname, hostname_len,
680 accept_fr_nonce, &incl_fr_opt, &fr_serverid);
683 if (reqmsg == DHCPV4_MSG_REQUEST)
684 msg = DHCPV4_MSG_NAK;
685 else if (reqmsg == DHCPV4_MSG_DISCOVER)
687 } else if (reqmsg == DHCPV4_MSG_DISCOVER)
688 msg = DHCPV4_MSG_OFFER;
689 else if (reqmsg == DHCPV4_MSG_REQUEST &&
690 ((reqaddr && reqaddr != a->addr) ||
691 (req->ciaddr.s_addr && req->ciaddr.s_addr != a->addr))) {
692 msg = DHCPV4_MSG_NAK;
694 * DHCP client requested an IP which we can't offer to him. Probably the
695 * client changed the network or the network has been changed. The reply
696 * type is set to DHCPV4_MSG_NAK, because the client should not use that IP.
698 * For modern devices we build an answer that includes a valid IP, like
699 * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to
700 * perform additional DHCP round trips.
706 * Buggy clients do serverid checking in nack messages; therefore set the
707 * serverid in nack messages triggered by a previous force renew equal to
708 * the server id in use at that time by the server
712 serverid = fr_serverid;
714 if (req->ciaddr.s_addr &&
715 ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) !=
716 (req->ciaddr.s_addr & iface->dhcpv4_mask.s_addr)))
717 req->ciaddr.s_addr = INADDR_ANY;
720 syslog(LOG_WARNING, "Received %s from %s on %s", dhcpv4_msg_to_string(reqmsg),
721 odhcpd_print_mac(req->chaddr, req->hlen), iface->name);
724 if (reqmsg == DHCPV4_MSG_RELEASE)
725 ubus_bcast_dhcp_event("dhcp.release", req->chaddr, req->hlen,
726 &req->ciaddr, hostname, iface->ifname);
728 if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
731 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
732 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &serverid);
737 reply.yiaddr.s_addr = a->addr;
739 val = htonl(leasetime);
740 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
742 if (leasetime != UINT32_MAX) {
743 val = htonl(500 * leasetime / 1000);
744 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
746 val = htonl(875 * leasetime / 1000);
747 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
750 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4,
751 &iface->dhcpv4_mask.s_addr);
754 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
755 strlen(a->hostname), a->hostname);
757 if (iface->dhcpv4_bcast.s_addr != INADDR_ANY)
758 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &iface->dhcpv4_bcast);
761 if (reqmsg == DHCPV4_MSG_REQUEST) {
762 struct dhcpv4_auth_forcerenew auth = {
766 .replay = {htonl(time(NULL)), htonl(++serial)},
771 memcpy(auth.key, a->key, sizeof(auth.key));
772 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
775 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE,
783 memset(&ifr, 0, sizeof(ifr));
784 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1);
786 if (!ioctl(sock, SIOCGIFMTU, &ifr)) {
787 uint16_t mtu = htons(ifr.ifr_mtu);
788 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu);
791 if (iface->search && iface->search_len <= 255)
792 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
793 iface->search_len, iface->search);
794 else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
795 uint8_t search_buf[256];
796 int len = dn_comp(_res.dnsrch[0], search_buf,
797 sizeof(search_buf), NULL, NULL);
799 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
803 if (iface->dhcpv4_router_cnt == 0)
804 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &iface->dhcpv4_local);
806 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER,
807 4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router);
810 if (iface->dhcpv4_dns_cnt == 0)
811 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &iface->dhcpv4_local);
813 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER,
814 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns);
817 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL);
819 struct sockaddr_in dest = *((struct sockaddr_in*)addr);
820 if (req->giaddr.s_addr) {
822 * relay agent is configured, send reply to the agent
824 dest.sin_addr = req->giaddr;
825 dest.sin_port = htons(DHCPV4_SERVER_PORT);
826 } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
828 * client has existing configuration (ciaddr is set) AND this address is
829 * not the address it used for the dhcp message
831 dest.sin_addr = req->ciaddr;
832 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
833 } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
834 req->hlen != reply.hlen || !reply.yiaddr.s_addr) {
836 * client requests a broadcast reply OR we can't offer an IP
838 dest.sin_addr.s_addr = INADDR_BROADCAST;
839 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
840 } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) {
842 * client has no previous configuration -> no IP, so we need to reply
843 * with a broadcast packet
845 dest.sin_addr.s_addr = INADDR_BROADCAST;
846 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
848 struct arpreq arp = {.arp_flags = ATF_COM};
851 * send reply to the newly (in this proccess) allocated IP
853 dest.sin_addr = reply.yiaddr;
854 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
856 memcpy(arp.arp_ha.sa_data, req->chaddr, 6);
857 memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa));
858 memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev));
860 if (ioctl(sock, SIOCSARP, &arp) < 0)
861 syslog(LOG_ERR, "ioctl(SIOCSARP): %m");
864 if (sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
865 (struct sockaddr*)&dest, sizeof(dest)) < 0)
866 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m",
867 dhcpv4_msg_to_string(msg),
868 dest.sin_addr.s_addr == INADDR_BROADCAST ?
869 "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
870 inet_ntoa(dest.sin_addr));
872 syslog(LOG_ERR, "Sent %s to %s - %s",
873 dhcpv4_msg_to_string(msg),
874 dest.sin_addr.s_addr == INADDR_BROADCAST ?
875 "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
876 inet_ntoa(dest.sin_addr));
880 if (msg == DHCPV4_MSG_ACK)
881 ubus_bcast_dhcp_event("dhcp.ack", req->chaddr, req->hlen, &reply.yiaddr,
882 hostname, iface->ifname);
886 static bool dhcpv4_assign(struct interface *iface, struct dhcp_assignment *a,
889 struct dhcp_assignment *c;
890 uint32_t start = ntohl(iface->dhcpv4_start_ip.s_addr);
891 uint32_t end = ntohl(iface->dhcpv4_end_ip.s_addr);
892 uint32_t count = end - start + 1;
895 /* Preconfigured IP address by static lease */
897 if (list_empty(&iface->dhcpv4_assignments)) {
898 list_add(&a->head, &iface->dhcpv4_assignments);
902 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
903 if (ntohl(c->addr) > ntohl(a->addr)) {
904 list_add_tail(&a->head, &c->head);
906 } else if (ntohl(a->addr) == ntohl(c->addr))
911 /* try to assign the IP the client asked for */
912 if (start <= ntohl(raddr) && ntohl(raddr) <= end &&
913 !config_find_lease_by_ipaddr(raddr)) {
914 if (list_empty(&iface->dhcpv4_assignments)) {
915 list_add(&a->head, &iface->dhcpv4_assignments);
919 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
920 if (ntohl(c->addr) > ntohl(raddr)) {
921 list_add_tail(&a->head, &c->head);
925 syslog(LOG_INFO, "Assigning the IP the client asked for: %u.%u.%u.%u",
926 ((uint8_t *)&a->addr)[0], ((uint8_t *)&a->addr)[1],
927 ((uint8_t *)&a->addr)[2], ((uint8_t *)&a->addr)[3]);
930 } else if (ntohl(raddr) == ntohl(c->addr))
935 /* Seed RNG with checksum of hwaddress */
936 for (size_t i = 0; i < sizeof(a->hwaddr); ++i) {
937 /* Knuth's multiplicative method */
938 uint8_t o = a->hwaddr[i];
939 seed += (o*2654435761) % UINT32_MAX;
944 for (uint32_t i = 0, try = (((uint32_t)rand()) % count) + start; i < count;
945 ++i, try = (((try - start) + 1) % count) + start) {
947 if (config_find_lease_by_ipaddr(htonl(try)))
950 if (list_empty(&iface->dhcpv4_assignments)) {
951 list_add(&a->head, &iface->dhcpv4_assignments);
952 a->addr = htonl(try);
954 syslog(LOG_INFO, "Assigning mapped IP (empty list): %u.%u.%u.%u",
955 ((uint8_t *)&a->addr)[0], ((uint8_t *)&a->addr)[1],
956 ((uint8_t *)&a->addr)[2], ((uint8_t *)&a->addr)[3]);
961 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
962 if (ntohl(c->addr) > try) {
963 list_add_tail(&a->head, &c->head);
964 a->addr = htonl(try);
966 syslog(LOG_DEBUG, "Assigning mapped IP: %u.%u.%u.%u (try %u of %u)",
967 ((uint8_t *)&a->addr)[0], ((uint8_t *)&a->addr)[1],
968 ((uint8_t *)&a->addr)[2], ((uint8_t *)&a->addr)[3],
972 } else if (try == ntohl(c->addr))
977 syslog(LOG_WARNING, "Can't assign any IP address -> address space is full");
982 static struct dhcp_assignment*
983 dhcpv4_lease(struct interface *iface, enum dhcpv4_msg msg, const uint8_t *mac,
984 const uint32_t reqaddr, uint32_t *leasetime, const char *hostname,
985 const size_t hostname_len, const bool accept_fr_nonce, bool *incl_fr_opt,
986 uint32_t *fr_serverid)
988 struct dhcp_assignment *a = find_assignment_by_hwaddr(iface, mac);
989 struct lease *l = config_find_lease_by_mac(mac);
990 time_t now = odhcpd_time();
992 if (l && a && a->lease != l) {
997 if (a && (a->flags & OAF_BOUND) && a->fr_ip) {
998 *fr_serverid = a->fr_ip->addr.addr.in.s_addr;
1002 if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
1003 bool assigned = !!a;
1006 if (!iface->no_dynamic_dhcp || l) {
1007 /* Create new binding */
1008 a = calloc(1, sizeof(*a));
1010 syslog(LOG_ERR, "Failed to calloc binding on interface %s",
1014 memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
1015 /* Set valid time to 0 for static lease indicating */
1016 /* infinite lifetime otherwise current time */
1017 a->valid_until = l ? 0 : now;
1018 a->dhcp_free_cb = dhcpv4_free_assignment;
1020 a->flags = OAF_DHCPV4;
1021 a->addr = l ? l->ipaddr : INADDR_ANY;
1023 assigned = dhcpv4_assign(iface, a, reqaddr);
1026 a->flags |= OAF_STATIC;
1029 a->hostname = strdup(l->hostname);
1032 a->leasetime = l->leasetime;
1034 list_add(&a->lease_list, &l->assignments);
1038 } else if (((a->addr & iface->dhcpv4_mask.s_addr) !=
1039 (iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) &&
1040 !(a->flags & OAF_STATIC)) {
1042 a->addr = INADDR_ANY;
1044 assigned = dhcpv4_assign(iface, a, reqaddr);
1048 uint32_t my_leasetime;
1051 my_leasetime = a->leasetime;
1053 my_leasetime = iface->dhcpv4_leasetime;
1055 if ((*leasetime == 0) || (my_leasetime < *leasetime))
1056 *leasetime = my_leasetime;
1058 if (msg == DHCPV4_MSG_DISCOVER) {
1059 a->flags &= ~OAF_BOUND;
1061 *incl_fr_opt = accept_fr_nonce;
1062 if (!(a->flags & OAF_STATIC))
1063 a->valid_until = now;
1065 if ((!(a->flags & OAF_STATIC) || !a->hostname) && hostname_len > 0) {
1066 a->hostname = realloc(a->hostname, hostname_len + 1);
1068 memcpy(a->hostname, hostname, hostname_len);
1069 a->hostname[hostname_len] = 0;
1071 if (odhcpd_valid_hostname(a->hostname))
1072 a->flags &= ~OAF_BROKEN_HOSTNAME;
1074 a->flags |= OAF_BROKEN_HOSTNAME;
1078 if (!(a->flags & OAF_BOUND)) {
1079 a->accept_fr_nonce = accept_fr_nonce;
1080 *incl_fr_opt = accept_fr_nonce;
1081 odhcpd_urandom(a->key, sizeof(a->key));
1082 a->flags |= OAF_BOUND;
1084 *incl_fr_opt = false;
1086 if (!(a->flags & OAF_STATIC))
1087 a->valid_until = ((*leasetime == UINT32_MAX) ? 0 : (time_t)(now + *leasetime));
1089 } else if (!assigned && a) {
1090 /* Cleanup failed assignment */
1095 } else if (msg == DHCPV4_MSG_RELEASE && a) {
1096 a->flags &= ~OAF_BOUND;
1098 if (!(a->flags & OAF_STATIC))
1099 a->valid_until = now - 1;
1101 } else if (msg == DHCPV4_MSG_DECLINE && a) {
1102 a->flags &= ~OAF_BOUND;
1104 if (!(a->flags & OAF_STATIC)) {
1105 memset(a->hwaddr, 0, sizeof(a->hwaddr));
1106 a->valid_until = now + 3600; /* Block address for 1h */
1110 dhcpv6_ia_write_statefile();