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 // Magic option for hnet internal (4B enterprise ID, 1B data-len, 1B subopt-code, 1B subopt-len)
42 static uint8_t hnet_internal_data[7] = {0x00, 0x00, 0x76, 0xfe, 2, 1, 0};
44 // Create socket and register events
51 int setup_dhcpv4_interface(struct interface *iface, bool enable)
53 if (iface->dhcpv4_event.uloop.fd > 0) {
54 uloop_fd_delete(&iface->dhcpv4_event.uloop);
55 close(iface->dhcpv4_event.uloop.fd);
56 iface->dhcpv4_event.uloop.fd = -1;
59 if (iface->dhcpv4 && enable) {
60 if (!iface->dhcpv4_assignments.next)
61 INIT_LIST_HEAD(&iface->dhcpv4_assignments);
63 int sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
65 // Basic IPv6 configuration
67 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
68 setsockopt(sock, SOL_SOCKET, SO_BROADCAST, &val, sizeof(val));
69 setsockopt(sock, IPPROTO_IP, IP_PKTINFO, &val, sizeof(val));
71 val = IPTOS_PREC_INTERNETCONTROL;
72 setsockopt(sock, IPPROTO_IP, IP_TOS, &val, sizeof(val));
74 val = IP_PMTUDISC_DONT;
75 setsockopt(sock, IPPROTO_IP, IP_MTU_DISCOVER, &val, sizeof(val));
77 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE,
78 iface->ifname, strlen(iface->ifname));
80 struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT),
83 if (bind(sock, (struct sockaddr*)&bind_addr, sizeof(bind_addr))) {
84 syslog(LOG_ERR, "Failed to open DHCPv4 server socket: %s",
90 if (ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) {
91 syslog(LOG_ERR, "Invalid DHCP range");
95 // Create a range if not specified
97 strncpy(ifreq.ifr_name, iface->ifname, sizeof(ifreq.ifr_name));
99 struct sockaddr_in *saddr = (struct sockaddr_in*)&ifreq.ifr_addr;
100 struct sockaddr_in *smask = (struct sockaddr_in*)&ifreq.ifr_netmask;
101 if (!(iface->dhcpv4_start.s_addr & htonl(0xffff0000)) &&
102 !(iface->dhcpv4_end.s_addr & htonl(0xffff0000)) &&
103 !ioctl(sock, SIOCGIFADDR, &ifreq)) {
104 struct in_addr addr = saddr->sin_addr;
106 ioctl(sock, SIOCGIFNETMASK, &ifreq);
107 struct in_addr mask = smask->sin_addr;
109 uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
110 uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
112 if (start && end && start < end &&
113 start > ntohl(addr.s_addr & ~mask.s_addr) &&
114 (start & ntohl(mask.s_addr)) == start &&
115 (end & ntohl(mask.s_addr)) == end) {
116 iface->dhcpv4_start.s_addr = htonl(start) |
117 (addr.s_addr & mask.s_addr);
118 iface->dhcpv4_end.s_addr = htonl(end) |
119 (addr.s_addr & mask.s_addr);
120 } else if (ntohl(mask.s_addr) <= 0xffffffc0) {
121 start = addr.s_addr & mask.s_addr;
122 end = addr.s_addr & mask.s_addr;
124 if (ntohl(mask.s_addr) <= 0xffffff00) {
125 iface->dhcpv4_start.s_addr = start | htonl(100);
126 iface->dhcpv4_end.s_addr = end | htonl(250);
128 iface->dhcpv4_start.s_addr = start | htonl(10);
129 iface->dhcpv4_end.s_addr = end | htonl(59);
136 // Parse static entries
138 list_for_each_entry(lease, &leases, head) {
140 size_t hostlen = strlen(lease->hostname) + 1;
141 struct dhcpv4_assignment *a = calloc(1, sizeof(*a) + hostlen);
143 a->addr = ntohl(lease->ipaddr.s_addr);
144 memcpy(a->hwaddr, lease->mac.ether_addr_octet, sizeof(a->hwaddr));
145 memcpy(a->hostname, lease->hostname, hostlen);
147 // Assign to all interfaces
148 struct dhcpv4_assignment *c;
149 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
150 if (c->addr > a->addr) {
151 list_add_tail(&a->head, &c->head);
152 } else if (c->addr == a->addr) {
153 // Already an assignment with that number
162 // Clean invalid assignments
163 struct dhcpv4_assignment *a, *n;
164 list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
165 if ((htonl(a->addr) & smask->sin_addr.s_addr) !=
166 (saddr->sin_addr.s_addr & smask->sin_addr.s_addr)) {
173 if (iface->dhcpv4_leasetime < 60)
174 iface->dhcpv4_leasetime = 43200;
176 iface->dhcpv4_event.uloop.fd = sock;
177 iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
178 odhcpd_register(&iface->dhcpv4_event);
179 } else if (iface->dhcpv4_assignments.next) {
180 while (!list_empty(&iface->dhcpv4_assignments)) {
181 struct dhcpv4_assignment *a = list_first_entry(&iface->dhcpv4_assignments,
182 struct dhcpv4_assignment, head);
193 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
194 uint8_t type, uint8_t len, const void *data)
196 uint8_t *c = *cookie;
197 if (*cookie + 2 + len > (uint8_t*)&msg[1])
202 memcpy(c, data, len);
208 // Simple DHCPv6-server for information requests
209 static void handle_dhcpv4(void *addr, void *data, size_t len,
210 struct interface *iface)
215 struct dhcpv4_message *req = data;
216 if (len < offsetof(struct dhcpv4_message, options) + 4 ||
217 req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
220 int sock = iface->dhcpv4_event.uloop.fd;
221 struct sockaddr_in ifaddr;
222 struct sockaddr_in ifnetmask;
224 syslog(LOG_NOTICE, "Got DHCPv4 request");
227 memcpy(ifreq.ifr_name, iface->ifname, sizeof(ifreq.ifr_name));
228 if (ioctl(sock, SIOCGIFADDR, &ifreq)) {
229 syslog(LOG_WARNING, "DHCPv4 failed to detect address: %s", strerror(errno));
233 memcpy(&ifaddr, &ifreq.ifr_addr, sizeof(ifaddr));
234 if (ioctl(sock, SIOCGIFNETMASK, &ifreq))
237 memcpy(&ifnetmask, &ifreq.ifr_netmask, sizeof(ifnetmask));
238 uint32_t network = ifaddr.sin_addr.s_addr & ifnetmask.sin_addr.s_addr;
240 if ((iface->dhcpv4_start.s_addr & ifnetmask.sin_addr.s_addr) != network ||
241 (iface->dhcpv4_end.s_addr & ifnetmask.sin_addr.s_addr) != network) {
242 syslog(LOG_WARNING, "DHCPv4 range out of assigned network");
246 struct ifreq ifr = {.ifr_name = ""};
247 strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
249 struct dhcpv4_message reply = {
250 .op = DHCPV4_BOOTREPLY,
257 .ciaddr = {INADDR_ANY},
258 .giaddr = req->giaddr,
259 .siaddr = ifaddr.sin_addr,
261 memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr));
263 reply.options[0] = 0x63;
264 reply.options[1] = 0x82;
265 reply.options[2] = 0x53;
266 reply.options[3] = 0x63;
268 uint8_t *cookie = &reply.options[4];
269 uint8_t reqmsg = DHCPV4_MSG_REQUEST;
270 uint8_t msg = DHCPV4_MSG_ACK;
272 struct in_addr reqaddr = {INADDR_ANY};
276 uint8_t *start = &req->options[4];
277 uint8_t *end = ((uint8_t*)data) + len;
278 struct dhcpv4_option *opt;
279 dhcpv4_for_each_option(start, end, opt) {
280 if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1) {
281 reqmsg = opt->data[0];
282 } else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
283 memcpy(hostname, opt->data, opt->len);
284 hostname[opt->len] = 0;
285 } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4) {
286 memcpy(&reqaddr, opt->data, 4);
287 } else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
288 if (memcmp(opt->data, &ifaddr.sin_addr, 4))
290 } else if (opt->type == DHCPV4_OPT_VENDOR_SPECIFIC_INFORMATION &&
291 opt->len == sizeof(hnet_internal_data)) {
292 if (!memcmp(opt->data, hnet_internal_data, sizeof(hnet_internal_data)))
293 return; // Ignoring hnet internal routers
297 if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
298 reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
299 reqmsg != DHCPV4_MSG_RELEASE)
302 struct dhcpv4_assignment *lease = NULL;
303 if (reqmsg != DHCPV4_MSG_INFORM)
304 lease = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr, hostname);
307 if (reqmsg == DHCPV4_MSG_REQUEST)
308 msg = DHCPV4_MSG_NAK;
309 else if (reqmsg == DHCPV4_MSG_DISCOVER)
311 } else if (reqmsg == DHCPV4_MSG_DISCOVER) {
312 msg = DHCPV4_MSG_OFFER;
315 if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
318 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
319 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &ifaddr.sin_addr);
322 reply.yiaddr.s_addr = htonl(lease->addr);
324 uint32_t val = htonl(iface->dhcpv4_leasetime);
325 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
327 val = htonl(500 * iface->dhcpv4_leasetime / 1000);
328 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
330 val = htonl(875 * iface->dhcpv4_leasetime / 1000);
331 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
333 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4, &ifnetmask.sin_addr);
335 if (lease->hostname[0])
336 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
337 strlen(lease->hostname), lease->hostname);
339 if (!ioctl(sock, SIOCGIFBRDADDR, &ifr)) {
340 struct sockaddr_in *ina = (struct sockaddr_in*)&ifr.ifr_broadaddr;
341 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &ina->sin_addr);
345 if (!ioctl(sock, SIOCGIFMTU, &ifr)) {
346 uint16_t mtu = htons(ifr.ifr_mtu);
347 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu);
352 if (dn_expand(iface->search, iface->search + iface->search_len,
353 iface->search, b, sizeof(b)) > 0)
354 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DOMAIN, strlen(b), b);
355 } else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
356 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DOMAIN,
357 strlen(_res.dnsrch[0]), _res.dnsrch[0]);
360 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &ifaddr.sin_addr);
364 if (iface->dhcpv4_dns_cnt == 0)
365 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &ifaddr.sin_addr);
367 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER,
368 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns);
371 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL);
373 struct sockaddr_in dest = *((struct sockaddr_in*)addr);
374 if (req->giaddr.s_addr) {
375 dest.sin_addr = req->giaddr;
376 dest.sin_port = htons(DHCPV4_SERVER_PORT);
377 } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
378 dest.sin_addr = req->ciaddr;
379 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
380 } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
381 req->hlen != reply.hlen) {
382 dest.sin_addr.s_addr = INADDR_BROADCAST;
383 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
385 dest.sin_addr = reply.yiaddr;
386 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
388 struct arpreq arp = {.arp_flags = ATF_COM};
389 memcpy(arp.arp_ha.sa_data, req->chaddr, 6);
390 memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa));
391 memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev));
392 ioctl(sock, SIOCSARP, &arp);
395 sendto(sock, &reply, sizeof(reply), MSG_DONTWAIT,
396 (struct sockaddr*)&dest, sizeof(dest));
400 static bool dhcpv4_assign(struct interface *iface,
401 struct dhcpv4_assignment *assign, uint32_t raddr)
403 const unsigned tries = 10;
404 uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
405 uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
406 uint32_t count = end - start + 1;
408 // Seed RNG with checksum of DUID
410 for (size_t i = 0; i < sizeof(assign->hwaddr); ++i)
411 seed += assign->hwaddr[i];
414 // Try to assign up to 100x
415 for (unsigned i = 0; i < tries; ++i) {
416 uint32_t try = (((uint32_t)rand()) % count) + start;
417 if (i == 0 && raddr >= start && raddr <= end)
419 else if (i == tries - 1)
422 if (list_empty(&iface->dhcpv4_assignments)) {
424 list_add(&assign->head, &iface->dhcpv4_assignments);
428 struct dhcpv4_assignment *c;
429 list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
432 list_add_tail(&assign->head, &c->head);
434 } else if (c->addr == try) {
447 static struct dhcpv4_assignment* dhcpv4_lease(struct interface *iface,
448 enum dhcpv4_msg msg, const uint8_t *mac, struct in_addr reqaddr,
449 const char *hostname)
451 struct dhcpv4_assignment *lease = NULL;
452 uint32_t raddr = ntohl(reqaddr.s_addr);
453 time_t now = odhcpd_time();
455 struct dhcpv4_assignment *c, *n, *a = NULL;
456 list_for_each_entry_safe(c, n, &iface->dhcpv4_assignments, head) {
457 if (c->addr == raddr && !memcmp(c->hwaddr, mac, 6)) {
460 } else if (c->valid_until < now) {
466 bool update_state = false;
467 if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
469 size_t hostlen = strlen(hostname) + 1;
471 if (!a && !iface->no_dynamic_dhcp) { // Create new binding
472 a = calloc(1, sizeof(*a) + hostlen);
473 memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
474 memcpy(a->hostname, hostname, hostlen);
476 assigned = dhcpv4_assign(iface, a, raddr);
479 if (assigned && !a->hostname[0] && hostname) {
480 a = realloc(a, sizeof(*a) + hostlen);
481 memcpy(a->hostname, hostname, hostlen);
484 a->head.next->prev = &a->head;
485 a->head.prev->next = &a->head;
488 // Was only a solicitation: mark binding for removal
489 if (assigned && a->valid_until < now) {
490 a->valid_until = (msg == DHCPV4_MSG_DISCOVER) ? 0 :
491 (now + iface->dhcpv4_leasetime);
492 } else if (!assigned && a) { // Cleanup failed assignment
499 } else if (msg == DHCPV4_MSG_RELEASE) {
504 } else if (msg == DHCPV4_MSG_DECLINE) {
505 memset(a->hwaddr, 0, sizeof(a->hwaddr));
506 a->valid_until = now + 3600; // Block address for 1h
511 dhcpv6_write_statefile();