2 * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License v2 as published by
6 * the Free Software Foundation.
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
24 #include <net/if_arp.h>
25 #include <netinet/ip.h>
26 #include <sys/ioctl.h>
27 #include <sys/timerfd.h>
28 #include <arpa/inet.h>
35 static void handle_dhcpv4(void *addr, void *data, size_t len,
36 struct interface *iface);
37 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
38 enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr,
39 const char *hostname);
42 // Create socket and register events
49 int setup_dhcpv4_interface(struct interface *iface, bool enable)
51 if (iface->dhcpv4_event.uloop.fd > 0) {
52 close(iface->dhcpv4_event.uloop.fd);
53 iface->dhcpv4_event.uloop.fd = -1;
56 if (iface->dhcpv4 && enable) {
57 if (!iface->dhcpv4_assignments.next)
58 INIT_LIST_HEAD(&iface->dhcpv4_assignments);
60 int sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
62 // Basic IPv6 configuration
64 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
65 setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &val, sizeof(val));
66 setsockopt(sock, IPPROTO_IP, IP_PKTINFO, &val, sizeof(val));
68 val = IPTOS_CLASS_CS6;
69 setsockopt(sock, IPPROTO_IP, IP_TOS, &val, sizeof(val));
71 val = IP_PMTUDISC_DONT;
72 setsockopt(sock, IPPROTO_IP, IP_MTU_DISCOVER, &val, sizeof(val));
74 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE,
75 iface->ifname, strlen(iface->ifname));
77 struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT),
80 if (bind(sock, (struct sockaddr*)&bind_addr, sizeof(bind_addr))) {
81 syslog(LOG_ERR, "Failed to open DHCPv4 server socket: %s",
87 if (ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) {
88 syslog(LOG_ERR, "Invalid DHCP range");
92 // Create a range if not specified
94 strncpy(ifreq.ifr_name, iface->ifname, sizeof(ifreq.ifr_name));
96 struct sockaddr_in *saddr = (struct sockaddr_in*)&ifreq.ifr_addr;
97 struct sockaddr_in *smask = (struct sockaddr_in*)&ifreq.ifr_netmask;
98 if (!(iface->dhcpv4_start.s_addr & htonl(0xffff0000)) &&
99 !(iface->dhcpv4_end.s_addr & htonl(0xffff0000)) &&
100 !ioctl(sock, SIOCGIFADDR, &ifreq)) {
101 struct in_addr addr = saddr->sin_addr;
103 ioctl(sock, SIOCGIFNETMASK, &ifreq);
104 struct in_addr mask = smask->sin_addr;
106 uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
107 uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
109 if (start && end && start < end &&
110 start > ntohl(addr.s_addr & ~mask.s_addr) &&
111 (start & ntohl(mask.s_addr)) == start &&
112 (end & ntohl(mask.s_addr)) == end) {
113 iface->dhcpv4_start.s_addr = htonl(start) |
114 (addr.s_addr & mask.s_addr);
115 iface->dhcpv4_end.s_addr = htonl(end) |
116 (addr.s_addr & mask.s_addr);
117 } else if (ntohl(mask.s_addr) <= 0xffffffc0) {
118 start = addr.s_addr & mask.s_addr;
119 end = addr.s_addr & mask.s_addr;
121 if (ntohl(mask.s_addr) <= 0xffffff00) {
122 iface->dhcpv4_start.s_addr = start | htonl(100);
123 iface->dhcpv4_end.s_addr = end | htonl(250);
125 iface->dhcpv4_start.s_addr = start | htonl(10);
126 iface->dhcpv4_end.s_addr = end | htonl(59);
133 // Parse static entries
135 list_for_each_entry(lease, &leases, head) {
137 size_t hostlen = strlen(lease->hostname) + 1;
138 struct dhcpv4_assignment *a = calloc(1, sizeof(*a) + hostlen);
140 a->addr = ntohl(lease->ipaddr.s_addr);
141 memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
142 memcpy(a->hostname, lease->hostname, hostlen);
144 // Assign to all interfaces
145 struct dhcpv4_assignment *c;
146 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
147 if (c->addr > a->addr) {
148 list_add_tail(&a->head, &c->head);
149 } else if (c->addr == a->addr) {
150 // Already an assignment with that number
159 // Clean invalid assignments
160 struct dhcpv4_assignment *a, *n;
161 list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
162 if ((htonl(a->addr) & smask->sin_addr.s_addr) !=
163 (saddr->sin_addr.s_addr & smask->sin_addr.s_addr)) {
170 if (iface->dhcpv4_leasetime < 60)
171 iface->dhcpv4_leasetime = 43200;
173 iface->dhcpv4_event.uloop.fd = sock;
174 iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
175 odhcpd_register(&iface->dhcpv4_event);
176 } else if (iface->dhcpv4_assignments.next) {
177 while (!list_empty(&iface->dhcpv4_assignments)) {
178 struct dhcpv4_assignment *a = list_first_entry(&iface->dhcpv4_assignments,
179 struct dhcpv4_assignment, head);
190 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
191 uint8_t type, uint8_t len, const void *data)
193 uint8_t *c = *cookie;
194 if (*cookie + 2 + len > (uint8_t*)&msg[1])
199 memcpy(c, data, len);
205 // Simple DHCPv6-server for information requests
206 static void handle_dhcpv4(void *addr, void *data, size_t len,
207 struct interface *iface)
212 struct dhcpv4_message *req = data;
213 if (len < offsetof(struct dhcpv4_message, options) + 4 ||
214 req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
217 int sock = iface->dhcpv4_event.uloop.fd;
218 struct sockaddr_in ifaddr;
219 struct sockaddr_in ifnetmask;
221 syslog(LOG_NOTICE, "Got DHCPv4 request");
224 memcpy(ifreq.ifr_name, iface->ifname, sizeof(ifreq.ifr_name));
225 if (ioctl(sock, SIOCGIFADDR, &ifreq)) {
226 syslog(LOG_WARNING, "DHCPv4 failed to detect address: %s", strerror(errno));
230 memcpy(&ifaddr, &ifreq.ifr_addr, sizeof(ifaddr));
231 if (ioctl(sock, SIOCGIFNETMASK, &ifreq))
234 memcpy(&ifnetmask, &ifreq.ifr_netmask, sizeof(ifnetmask));
235 uint32_t network = ifaddr.sin_addr.s_addr & ifnetmask.sin_addr.s_addr;
237 if ((iface->dhcpv4_start.s_addr & ifnetmask.sin_addr.s_addr) != network ||
238 (iface->dhcpv4_end.s_addr & ifnetmask.sin_addr.s_addr) != network) {
239 syslog(LOG_WARNING, "DHCPv4 range out of assigned network");
243 struct ifreq ifr = {.ifr_name = ""};
244 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
246 struct dhcpv4_message reply = {
247 .op = DHCPV4_BOOTREPLY,
254 .ciaddr = {INADDR_ANY},
255 .giaddr = req->giaddr,
256 .siaddr = ifaddr.sin_addr,
258 memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr));
260 reply.options[0] = 0x63;
261 reply.options[1] = 0x82;
262 reply.options[2] = 0x53;
263 reply.options[3] = 0x63;
265 uint8_t *cookie = &reply.options[4];
266 uint8_t reqmsg = DHCPV4_MSG_REQUEST;
267 uint8_t msg = DHCPV4_MSG_ACK;
269 struct in_addr reqaddr = {INADDR_ANY};
273 uint8_t *start = &req->options[4];
274 uint8_t *end = ((uint8_t*)data) + len;
275 struct dhcpv4_option *opt;
276 dhcpv4_for_each_option(start, end, opt) {
277 if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1) {
278 reqmsg = opt->data[0];
279 } else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
280 memcpy(hostname, opt->data, opt->len);
281 hostname[opt->len] = 0;
282 } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4) {
283 memcpy(&reqaddr, opt->data, 4);
284 } else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
285 if (memcmp(opt->data, &ifaddr.sin_addr, 4))
290 if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
291 reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
292 reqmsg != DHCPV4_MSG_RELEASE)
295 struct dhcpv4_assignment *lease = NULL;
296 if (reqmsg != DHCPV4_MSG_INFORM)
297 lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, hostname);
300 if (reqmsg == DHCPV4_MSG_REQUEST)
301 msg = DHCPV4_MSG_NAK;
302 else if (reqmsg == DHCPV4_MSG_DISCOVER)
304 } else if (reqmsg == DHCPV4_MSG_DISCOVER) {
305 msg = DHCPV4_MSG_OFFER;
308 if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
311 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
312 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &ifaddr.sin_addr);
315 reply.yiaddr.s_addr = htonl(lease->addr);
317 uint32_t val = htonl(iface->dhcpv4_leasetime);
318 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
320 val = htonl(500 * iface->dhcpv4_leasetime / 1000);
321 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
323 val = htonl(875 * iface->dhcpv4_leasetime / 1000);
324 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
326 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4, &ifnetmask.sin_addr);
328 if (lease->hostname[0])
329 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
330 strlen(lease->hostname), lease->hostname);
332 if (!ioctl(sock, SIOCGIFBRDADDR, &ifr)) {
333 struct sockaddr_in *ina = (struct sockaddr_in*)&ifr.ifr_broadaddr;
334 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &ina->sin_addr);
338 if (!ioctl(sock, SIOCGIFMTU, &ifr)) {
339 uint16_t mtu = htons(ifr.ifr_mtu);
340 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu);
345 if (dn_expand(iface->search, iface->search + iface->search_len,
346 iface->search, b, sizeof(b)) > 0)
347 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DOMAIN, strlen(b), b);
348 } else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
349 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DOMAIN,
350 strlen(_res.dnsrch[0]), _res.dnsrch[0]);
353 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr);
357 if (iface->dhcpv4_dns_cnt == 0)
358 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &ifaddr.sin_addr);
360 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER,
361 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns);
364 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL);
366 struct sockaddr_in dest = *((struct sockaddr_in*)addr);
367 if (req->giaddr.s_addr) {
368 dest.sin_addr = req->giaddr;
369 dest.sin_port = htons(DHCPV4_SERVER_PORT);
370 } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
371 dest.sin_addr = req->ciaddr;
372 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
373 } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
374 req->hlen != reply.hlen) {
375 dest.sin_addr.s_addr = INADDR_BROADCAST;
376 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
378 dest.sin_addr = reply.yiaddr;
379 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
381 struct arpreq arp = {.arp_flags = ATF_COM};
382 memcpy(arp.arp_ha.sa_data, req->chaddr, 6);
383 memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa));
384 memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev));
385 ioctl(sock, SIOCSARP, &arp);
388 sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
389 (struct sockaddr*)&dest, sizeof(dest));
393 static bool dhcpv4_assign(struct interface *iface,
394 struct dhcpv4_assignment *assign, uint32_t raddr)
396 const unsigned tries = 10;
397 uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
398 uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
399 uint32_t count = end - start + 1;
401 // Seed RNG with checksum of DUID
403 for (size_t i = 0; i < sizeof(assign->hwaddr); ++i)
404 seed += assign->hwaddr[i];
407 // Try to assign up to 100x
408 for (unsigned i = 0; i < tries; ++i) {
409 uint32_t try = (((uint32_t)rand()) % count) + start;
410 if (i == 0 && raddr >= start && raddr <= end)
412 else if (i == tries - 1)
415 if (list_empty(&iface->dhcpv4_assignments)) {
417 list_add(&assign->head, &iface->dhcpv4_assignments);
421 struct dhcpv4_assignment *c;
422 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
425 list_add_tail(&assign->head, &c->head);
427 } else if (c->addr == try) {
440 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
441 enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr,
442 const char *hostname)
444 struct dhcpv4_assignment *lease = NULL;
445 uint32_t raddr = ntohl(reqaddr.s_addr);
446 time_t now = odhcpd_time();
448 struct dhcpv4_assignment *c, *n, *a = NULL;
449 list_for_each_entry_safe(c, n, &iface->dhcpv4_assignments, head) {
450 if (c->addr == raddr && !memcmp(c->hwaddr, mac, 6)) {
453 } else if (c->valid_until < now) {
459 bool update_state = false;
460 if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
462 size_t hostlen = strlen(hostname) + 1;
464 if (!a && !iface->no_dynamic_dhcp) { // Create new binding
465 a = calloc(1, sizeof(*a) + hostlen);
466 memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
467 memcpy(a->hostname, hostname, hostlen);
469 assigned = dhcpv4_assign(iface, a, raddr);
472 if (assigned && !a->hostname[0] && hostname) {
473 a = realloc(a, sizeof(*a) + hostlen);
474 memcpy(a->hostname, hostname, hostlen);
477 a->head.next->prev = &a->head;
478 a->head.prev->next = &a->head;
481 // Was only a solicitation: mark binding for removal
482 if (assigned && a->valid_until < now) {
483 a->valid_until = (msg == DHCPV4_MSG_DISCOVER) ? 0 :
484 (now + iface->dhcpv4_leasetime);
485 } else if (!assigned && a) { // Cleanup failed assignment
492 } else if (msg == DHCPV4_MSG_RELEASE) {
497 } else if (msg == DHCPV4_MSG_DECLINE) {
498 memset(a->hwaddr, 0, sizeof(a->hwaddr));
499 a->valid_until = now + 3600; // Block address for 1h
504 dhcpv6_write_statefile();