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);
41 // Create socket and register events
48 int setup_dhcpv4_interface(struct interface *iface, bool enable)
50 if (iface->dhcpv4_event.uloop.fd > 0) {
51 uloop_fd_delete(&iface->dhcpv4_event.uloop);
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 syslog(LOG_ERR, "Failed to create DHCPv4 server socket: %s",
67 // Basic IPv6 configuration
69 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
70 setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &val, sizeof(val));
71 setsockopt(sock, IPPROTO_IP, IP_PKTINFO, &val, sizeof(val));
73 val = IPTOS_PREC_INTERNETCONTROL;
74 setsockopt(sock, IPPROTO_IP, IP_TOS, &val, sizeof(val));
76 val = IP_PMTUDISC_DONT;
77 setsockopt(sock, IPPROTO_IP, IP_MTU_DISCOVER, &val, sizeof(val));
79 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE,
80 iface->ifname, strlen(iface->ifname));
82 struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT),
85 if (bind(sock, (struct sockaddr*)&bind_addr, sizeof(bind_addr))) {
86 syslog(LOG_ERR, "Failed to open DHCPv4 server socket: %s",
92 if (ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) {
93 syslog(LOG_ERR, "Invalid DHCP range");
97 // Create a range if not specified
99 strncpy(ifreq.ifr_name, iface->ifname, sizeof(ifreq.ifr_name));
101 struct sockaddr_in *saddr = (struct sockaddr_in*)&ifreq.ifr_addr;
102 struct sockaddr_in *smask = (struct sockaddr_in*)&ifreq.ifr_netmask;
103 if (!(iface->dhcpv4_start.s_addr & htonl(0xffff0000)) &&
104 !(iface->dhcpv4_end.s_addr & htonl(0xffff0000)) &&
105 !ioctl(sock, SIOCGIFADDR, &ifreq)) {
106 struct in_addr addr = saddr->sin_addr;
108 ioctl(sock, SIOCGIFNETMASK, &ifreq);
109 struct in_addr mask = smask->sin_addr;
111 uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
112 uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
114 if (start && end && start < end &&
115 start > ntohl(addr.s_addr & ~mask.s_addr) &&
116 (start & ntohl(mask.s_addr)) == start &&
117 (end & ntohl(mask.s_addr)) == end) {
118 iface->dhcpv4_start.s_addr = htonl(start) |
119 (addr.s_addr & mask.s_addr);
120 iface->dhcpv4_end.s_addr = htonl(end) |
121 (addr.s_addr & mask.s_addr);
122 } else if (ntohl(mask.s_addr) <= 0xfffffff0) {
123 start = addr.s_addr & mask.s_addr;
124 end = addr.s_addr & mask.s_addr;
126 if (ntohl(mask.s_addr) <= 0xffffff00) {
127 iface->dhcpv4_start.s_addr = start | htonl(100);
128 iface->dhcpv4_end.s_addr = end | htonl(250);
129 } else if (ntohl(mask.s_addr) <= 0xffffffc0) {
130 iface->dhcpv4_start.s_addr = start | htonl(10);
131 iface->dhcpv4_end.s_addr = end | htonl(60);
133 iface->dhcpv4_start.s_addr = start | htonl(10);
134 iface->dhcpv4_end.s_addr = end | htonl(30);
141 // Parse static entries
143 list_for_each_entry(lease, &leases, head) {
145 size_t hostlen = strlen(lease->hostname) + 1;
146 struct dhcpv4_assignment *a = calloc(1, sizeof(*a) + hostlen);
148 syslog(LOG_ERR, "Calloc failed for static lease on interface %s",
152 a->addr = ntohl(lease->ipaddr.s_addr);
153 memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
154 memcpy(a->hostname, lease->hostname, hostlen);
156 // Assign to all interfaces
157 struct dhcpv4_assignment *c;
158 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
159 if (c->addr > a->addr) {
160 list_add_tail(&a->head, &c->head);
161 } else if (c->addr == a->addr) {
162 // Already an assignment with that number
171 // Clean invalid assignments
172 struct dhcpv4_assignment *a, *n;
173 list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
174 if ((htonl(a->addr) & smask->sin_addr.s_addr) !=
175 (saddr->sin_addr.s_addr & smask->sin_addr.s_addr)) {
182 if (iface->dhcpv4_leasetime < 60)
183 iface->dhcpv4_leasetime = 43200;
185 iface->dhcpv4_event.uloop.fd = sock;
186 iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
187 odhcpd_register(&iface->dhcpv4_event);
188 } else if (iface->dhcpv4_assignments.next) {
189 while (!list_empty(&iface->dhcpv4_assignments)) {
190 struct dhcpv4_assignment *a = list_first_entry(&iface->dhcpv4_assignments,
191 struct dhcpv4_assignment, head);
202 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
203 uint8_t type, uint8_t len, const void *data)
205 uint8_t *c = *cookie;
206 if (*cookie + 2 + len > (uint8_t*)&msg[1])
211 memcpy(c, data, len);
217 // Simple DHCPv6-server for information requests
218 static void handle_dhcpv4(void *addr, void *data, size_t len,
219 struct interface *iface)
224 struct dhcpv4_message *req = data;
225 if (len < offsetof(struct dhcpv4_message, options) + 4 ||
226 req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
229 int sock = iface->dhcpv4_event.uloop.fd;
230 struct sockaddr_in ifaddr;
231 struct sockaddr_in ifnetmask;
233 syslog(LOG_NOTICE, "Got DHCPv4 request");
236 memcpy(ifreq.ifr_name, iface->ifname, sizeof(ifreq.ifr_name));
237 if (ioctl(sock, SIOCGIFADDR, &ifreq)) {
238 syslog(LOG_WARNING, "DHCPv4 failed to detect address: %s", strerror(errno));
242 memcpy(&ifaddr, &ifreq.ifr_addr, sizeof(ifaddr));
243 if (ioctl(sock, SIOCGIFNETMASK, &ifreq))
246 memcpy(&ifnetmask, &ifreq.ifr_netmask, sizeof(ifnetmask));
247 uint32_t network = ifaddr.sin_addr.s_addr & ifnetmask.sin_addr.s_addr;
249 if ((iface->dhcpv4_start.s_addr & ifnetmask.sin_addr.s_addr) != network ||
250 (iface->dhcpv4_end.s_addr & ifnetmask.sin_addr.s_addr) != network) {
251 syslog(LOG_WARNING, "DHCPv4 range out of assigned network");
255 struct ifreq ifr = {.ifr_name = ""};
256 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
258 struct dhcpv4_message reply = {
259 .op = DHCPV4_BOOTREPLY,
266 .ciaddr = {INADDR_ANY},
267 .giaddr = req->giaddr,
268 .siaddr = ifaddr.sin_addr,
270 memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr));
272 reply.options[0] = 0x63;
273 reply.options[1] = 0x82;
274 reply.options[2] = 0x53;
275 reply.options[3] = 0x63;
277 uint8_t *cookie = &reply.options[4];
278 uint8_t reqmsg = DHCPV4_MSG_REQUEST;
279 uint8_t msg = DHCPV4_MSG_ACK;
281 struct in_addr reqaddr = {INADDR_ANY};
285 uint8_t *start = &req->options[4];
286 uint8_t *end = ((uint8_t*)data) + len;
287 struct dhcpv4_option *opt;
288 dhcpv4_for_each_option(start, end, opt) {
289 if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1) {
290 reqmsg = opt->data[0];
291 } else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
292 memcpy(hostname, opt->data, opt->len);
293 hostname[opt->len] = 0;
294 } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4) {
295 memcpy(&reqaddr, opt->data, 4);
296 } else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
297 if (memcmp(opt->data, &ifaddr.sin_addr, 4))
299 } else if (iface->filter_class && opt->type == DHCPV4_OPT_USER_CLASS) {
300 uint8_t *c = opt->data, *cend = &opt->data[opt->len];
301 for (; c < cend && &c[*c] < cend; c = &c[1 + *c]) {
302 size_t elen = strlen(iface->filter_class);
303 if (*c == elen && !memcmp(&c[1], iface->filter_class, elen))
304 return; // Ignore from homenet
309 if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
310 reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
311 reqmsg != DHCPV4_MSG_RELEASE)
314 struct dhcpv4_assignment *lease = NULL;
315 if (reqmsg != DHCPV4_MSG_INFORM)
316 lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, hostname);
319 if (reqmsg == DHCPV4_MSG_REQUEST)
320 msg = DHCPV4_MSG_NAK;
321 else if (reqmsg == DHCPV4_MSG_DISCOVER)
323 } else if (reqmsg == DHCPV4_MSG_DISCOVER) {
324 msg = DHCPV4_MSG_OFFER;
327 if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
330 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
331 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &ifaddr.sin_addr);
334 reply.yiaddr.s_addr = htonl(lease->addr);
336 uint32_t val = htonl(iface->dhcpv4_leasetime);
337 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
339 val = htonl(500 * iface->dhcpv4_leasetime / 1000);
340 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
342 val = htonl(875 * iface->dhcpv4_leasetime / 1000);
343 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
345 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4, &ifnetmask.sin_addr);
347 if (lease->hostname[0])
348 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
349 strlen(lease->hostname), lease->hostname);
351 if (!ioctl(sock, SIOCGIFBRDADDR, &ifr)) {
352 struct sockaddr_in *ina = (struct sockaddr_in*)&ifr.ifr_broadaddr;
353 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &ina->sin_addr);
357 if (!ioctl(sock, SIOCGIFMTU, &ifr)) {
358 uint16_t mtu = htons(ifr.ifr_mtu);
359 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu);
364 if (dn_expand(iface->search, iface->search + iface->search_len,
365 iface->search, b, sizeof(b)) > 0)
366 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DOMAIN, strlen(b), b);
367 } else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
368 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DOMAIN,
369 strlen(_res.dnsrch[0]), _res.dnsrch[0]);
372 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr);
376 if (iface->dhcpv4_dns_cnt == 0)
377 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &ifaddr.sin_addr);
379 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER,
380 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns);
383 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL);
385 struct sockaddr_in dest = *((struct sockaddr_in*)addr);
386 if (req->giaddr.s_addr) {
387 dest.sin_addr = req->giaddr;
388 dest.sin_port = htons(DHCPV4_SERVER_PORT);
389 } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
390 dest.sin_addr = req->ciaddr;
391 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
392 } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
393 req->hlen != reply.hlen) {
394 dest.sin_addr.s_addr = INADDR_BROADCAST;
395 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
397 dest.sin_addr = reply.yiaddr;
398 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
400 struct arpreq arp = {.arp_flags = ATF_COM};
401 memcpy(arp.arp_ha.sa_data, req->chaddr, 6);
402 memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa));
403 memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev));
404 ioctl(sock, SIOCSARP, &arp);
407 sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
408 (struct sockaddr*)&dest, sizeof(dest));
412 static bool dhcpv4_assign(struct interface *iface,
413 struct dhcpv4_assignment *assign, uint32_t raddr)
415 const unsigned tries = 10;
416 uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
417 uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
418 uint32_t count = end - start + 1;
420 // Seed RNG with checksum of DUID
422 for (size_t i = 0; i < sizeof(assign->hwaddr); ++i)
423 seed += assign->hwaddr[i];
426 // Try to assign up to 100x
427 for (unsigned i = 0; i < tries; ++i) {
428 uint32_t try = (((uint32_t)rand()) % count) + start;
429 if (i == 0 && raddr >= start && raddr <= end)
431 else if (i == tries - 1)
434 if (list_empty(&iface->dhcpv4_assignments)) {
436 list_add(&assign->head, &iface->dhcpv4_assignments);
440 struct dhcpv4_assignment *c;
441 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
444 list_add_tail(&assign->head, &c->head);
446 } else if (c->addr == try) {
459 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
460 enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr,
461 const char *hostname)
463 struct dhcpv4_assignment *lease = NULL;
464 uint32_t raddr = ntohl(reqaddr.s_addr);
465 time_t now = odhcpd_time();
467 struct dhcpv4_assignment *c, *n, *a = NULL;
468 list_for_each_entry_safe(c, n, &iface->dhcpv4_assignments, head) {
469 if (c->addr == raddr && !memcmp(c->hwaddr, mac, 6)) {
472 } else if (c->valid_until < now) {
478 bool update_state = false;
479 if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
481 size_t hostlen = strlen(hostname) + 1;
483 if (!a && !iface->no_dynamic_dhcp) { // Create new binding
484 a = calloc(1, sizeof(*a) + hostlen);
486 syslog(LOG_ERR, "Failed to calloc binding on interface %s", iface->ifname);
489 memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
490 memcpy(a->hostname, hostname, hostlen);
492 assigned = dhcpv4_assign(iface, a, raddr);
495 if (assigned && !a->hostname[0] && hostname) {
496 a = realloc(a, sizeof(*a) + hostlen);
498 syslog(LOG_ERR, "Failed to realloc binding on interface %s", iface->ifname);
501 memcpy(a->hostname, hostname, hostlen);
504 a->head.next->prev = &a->head;
505 a->head.prev->next = &a->head;
508 // Was only a solicitation: mark binding for removal
509 if (assigned && a->valid_until < now) {
510 a->valid_until = (msg == DHCPV4_MSG_DISCOVER) ? 0 :
511 (now + iface->dhcpv4_leasetime);
512 } else if (!assigned && a) { // Cleanup failed assignment
519 } else if (msg == DHCPV4_MSG_RELEASE) {
524 } else if (msg == DHCPV4_MSG_DECLINE) {
525 memset(a->hwaddr, 0, sizeof(a->hwaddr));
526 a->valid_until = now + 3600; // Block address for 1h
531 dhcpv6_write_statefile();