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.
25 #include <net/if_arp.h>
26 #include <netinet/ip.h>
27 #include <sys/ioctl.h>
28 #include <sys/timerfd.h>
29 #include <arpa/inet.h>
36 static void handle_dhcpv4(void *addr
, void *data
, size_t len
,
37 struct interface
*iface
, void *dest_addr
);
38 static struct dhcpv4_assignment
* dhcpv4_lease(struct interface
*iface
,
39 enum dhcpv4_msg msg
, const uint8_t *mac
, struct in_addr reqaddr
,
40 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 uloop_fd_delete(&iface
->dhcpv4_event
.uloop
);
53 close(iface
->dhcpv4_event
.uloop
.fd
);
54 iface
->dhcpv4_event
.uloop
.fd
= -1;
57 if (iface
->dhcpv4
&& enable
) {
58 if (!iface
->dhcpv4_assignments
.next
)
59 INIT_LIST_HEAD(&iface
->dhcpv4_assignments
);
61 int sock
= socket(AF_INET
, SOCK_DGRAM
| SOCK_CLOEXEC
, IPPROTO_UDP
);
63 syslog(LOG_ERR
, "Failed to create DHCPv4 server socket: %s",
68 // Basic IPv6 configuration
70 setsockopt(sock
, SOL_SOCKET
, SO_REUSEADDR
, &val
, sizeof(val
));
71 setsockopt(sock
, SOL_SOCKET
, SO_BROADCAST
, &val
, sizeof(val
));
72 setsockopt(sock
, IPPROTO_IP
, IP_PKTINFO
, &val
, sizeof(val
));
74 val
= IPTOS_PREC_INTERNETCONTROL
;
75 setsockopt(sock
, IPPROTO_IP
, IP_TOS
, &val
, sizeof(val
));
77 val
= IP_PMTUDISC_DONT
;
78 setsockopt(sock
, IPPROTO_IP
, IP_MTU_DISCOVER
, &val
, sizeof(val
));
80 setsockopt(sock
, SOL_SOCKET
, SO_BINDTODEVICE
,
81 iface
->ifname
, strlen(iface
->ifname
));
83 struct sockaddr_in bind_addr
= {AF_INET
, htons(DHCPV4_SERVER_PORT
),
86 if (bind(sock
, (struct sockaddr
*)&bind_addr
, sizeof(bind_addr
))) {
87 syslog(LOG_ERR
, "Failed to open DHCPv4 server socket: %s",
93 if (ntohl(iface
->dhcpv4_start
.s_addr
) > ntohl(iface
->dhcpv4_end
.s_addr
)) {
94 syslog(LOG_ERR
, "Invalid DHCP range");
98 // Create a range if not specified
100 strncpy(ifreq
.ifr_name
, iface
->ifname
, sizeof(ifreq
.ifr_name
));
102 struct sockaddr_in
*saddr
= (struct sockaddr_in
*)&ifreq
.ifr_addr
;
103 struct sockaddr_in
*smask
= (struct sockaddr_in
*)&ifreq
.ifr_netmask
;
104 if (!(iface
->dhcpv4_start
.s_addr
& htonl(0xffff0000)) &&
105 !(iface
->dhcpv4_end
.s_addr
& htonl(0xffff0000)) &&
106 !ioctl(sock
, SIOCGIFADDR
, &ifreq
)) {
107 struct in_addr addr
= saddr
->sin_addr
;
109 ioctl(sock
, SIOCGIFNETMASK
, &ifreq
);
110 struct in_addr mask
= smask
->sin_addr
;
112 uint32_t start
= ntohl(iface
->dhcpv4_start
.s_addr
);
113 uint32_t end
= ntohl(iface
->dhcpv4_end
.s_addr
);
115 if (start
&& end
&& start
< end
&&
116 start
> ntohl(addr
.s_addr
& ~mask
.s_addr
) &&
117 (start
& ntohl(mask
.s_addr
)) == start
&&
118 (end
& ntohl(mask
.s_addr
)) == end
) {
119 iface
->dhcpv4_start
.s_addr
= htonl(start
) |
120 (addr
.s_addr
& mask
.s_addr
);
121 iface
->dhcpv4_end
.s_addr
= htonl(end
) |
122 (addr
.s_addr
& mask
.s_addr
);
123 } else if (ntohl(mask
.s_addr
) <= 0xfffffff0) {
124 start
= addr
.s_addr
& mask
.s_addr
;
125 end
= addr
.s_addr
& mask
.s_addr
;
127 if (ntohl(mask
.s_addr
) <= 0xffffff00) {
128 iface
->dhcpv4_start
.s_addr
= start
| htonl(100);
129 iface
->dhcpv4_end
.s_addr
= end
| htonl(250);
130 } else if (ntohl(mask
.s_addr
) <= 0xffffffc0) {
131 iface
->dhcpv4_start
.s_addr
= start
| htonl(10);
132 iface
->dhcpv4_end
.s_addr
= end
| htonl(60);
133 } else if (ntohl(mask
.s_addr
) <= 0xffffffe0) {
134 iface
->dhcpv4_start
.s_addr
= start
| htonl(10);
135 iface
->dhcpv4_end
.s_addr
= end
| htonl(30);
137 iface
->dhcpv4_start
.s_addr
= start
| htonl(3);
138 iface
->dhcpv4_end
.s_addr
= end
| htonl(12);
145 // Parse static entries
147 list_for_each_entry(lease
, &leases
, head
) {
149 size_t hostlen
= strlen(lease
->hostname
) + 1;
150 struct dhcpv4_assignment
*a
= calloc(1, sizeof(*a
) + hostlen
);
152 syslog(LOG_ERR
, "Calloc failed for static lease on interface %s",
156 a
->addr
= ntohl(lease
->ipaddr
.s_addr
);
157 memcpy(a
->hwaddr
, lease
->mac
.ether_addr_octet
, sizeof(a
->hwaddr
));
158 memcpy(a
->hostname
, lease
->hostname
, hostlen
);
159 a
->valid_until
= LONG_MAX
;
161 // Assign to all interfaces
162 struct dhcpv4_assignment
*c
;
163 list_for_each_entry(c
, &iface
->dhcpv4_assignments
, head
) {
164 if (c
->addr
> a
->addr
) {
165 list_add_tail(&a
->head
, &c
->head
);
167 } else if (c
->addr
== a
->addr
) {
168 // Already an assignment with that number
172 if (&c
->head
== &iface
->dhcpv4_assignments
) {
173 list_add(&a
->head
, &iface
->dhcpv4_assignments
);
180 // Clean invalid assignments
181 struct dhcpv4_assignment
*a
, *n
;
182 list_for_each_entry_safe(a
, n
, &iface
->dhcpv4_assignments
, head
) {
183 if ((htonl(a
->addr
) & smask
->sin_addr
.s_addr
) !=
184 (iface
->dhcpv4_start
.s_addr
& smask
->sin_addr
.s_addr
)) {
191 if (iface
->dhcpv4_leasetime
< 60)
192 iface
->dhcpv4_leasetime
= 43200;
194 iface
->dhcpv4_event
.uloop
.fd
= sock
;
195 iface
->dhcpv4_event
.handle_dgram
= handle_dhcpv4
;
196 odhcpd_register(&iface
->dhcpv4_event
);
197 } else if (iface
->dhcpv4_assignments
.next
) {
198 while (!list_empty(&iface
->dhcpv4_assignments
)) {
199 struct dhcpv4_assignment
*a
= list_first_entry(&iface
->dhcpv4_assignments
,
200 struct dhcpv4_assignment
, head
);
211 static void dhcpv4_put(struct dhcpv4_message
*msg
, uint8_t **cookie
,
212 uint8_t type
, uint8_t len
, const void *data
)
214 uint8_t *c
= *cookie
;
215 if (*cookie
+ 2 + len
> (uint8_t*)&msg
[1])
220 memcpy(c
, data
, len
);
226 // Simple DHCPv6-server for information requests
227 static void handle_dhcpv4(void *addr
, void *data
, size_t len
,
228 struct interface
*iface
, _unused
void *dest_addr
)
233 struct dhcpv4_message
*req
= data
;
234 if (len
< offsetof(struct dhcpv4_message
, options
) + 4 ||
235 req
->op
!= DHCPV4_BOOTREQUEST
|| req
->hlen
!= 6)
238 int sock
= iface
->dhcpv4_event
.uloop
.fd
;
239 struct sockaddr_in ifaddr
;
240 struct sockaddr_in ifnetmask
;
242 syslog(LOG_NOTICE
, "Got DHCPv4 request");
245 memcpy(ifreq
.ifr_name
, iface
->ifname
, sizeof(ifreq
.ifr_name
));
246 if (ioctl(sock
, SIOCGIFADDR
, &ifreq
)) {
247 syslog(LOG_WARNING
, "DHCPv4 failed to detect address: %s", strerror(errno
));
251 memcpy(&ifaddr
, &ifreq
.ifr_addr
, sizeof(ifaddr
));
252 if (ioctl(sock
, SIOCGIFNETMASK
, &ifreq
))
255 memcpy(&ifnetmask
, &ifreq
.ifr_netmask
, sizeof(ifnetmask
));
256 uint32_t network
= ifaddr
.sin_addr
.s_addr
& ifnetmask
.sin_addr
.s_addr
;
258 if ((iface
->dhcpv4_start
.s_addr
& ifnetmask
.sin_addr
.s_addr
) != network
||
259 (iface
->dhcpv4_end
.s_addr
& ifnetmask
.sin_addr
.s_addr
) != network
) {
260 syslog(LOG_WARNING
, "DHCPv4 range out of assigned network");
264 struct ifreq ifr
= {.ifr_name
= ""};
265 strncpy(ifr
.ifr_name
, iface
->ifname
, sizeof(ifr
.ifr_name
));
267 struct dhcpv4_message reply
= {
268 .op
= DHCPV4_BOOTREPLY
,
275 .ciaddr
= {INADDR_ANY
},
276 .giaddr
= req
->giaddr
,
277 .siaddr
= ifaddr
.sin_addr
,
279 memcpy(reply
.chaddr
, req
->chaddr
, sizeof(reply
.chaddr
));
281 reply
.options
[0] = 0x63;
282 reply
.options
[1] = 0x82;
283 reply
.options
[2] = 0x53;
284 reply
.options
[3] = 0x63;
286 uint8_t *cookie
= &reply
.options
[4];
287 uint8_t reqmsg
= DHCPV4_MSG_REQUEST
;
288 uint8_t msg
= DHCPV4_MSG_ACK
;
290 struct in_addr reqaddr
= {INADDR_ANY
};
294 uint8_t *start
= &req
->options
[4];
295 uint8_t *end
= ((uint8_t*)data
) + len
;
296 struct dhcpv4_option
*opt
;
297 dhcpv4_for_each_option(start
, end
, opt
) {
298 if (opt
->type
== DHCPV4_OPT_MESSAGE
&& opt
->len
== 1) {
299 reqmsg
= opt
->data
[0];
300 } else if (opt
->type
== DHCPV4_OPT_HOSTNAME
&& opt
->len
> 0) {
301 memcpy(hostname
, opt
->data
, opt
->len
);
302 hostname
[opt
->len
] = 0;
303 } else if (opt
->type
== DHCPV4_OPT_IPADDRESS
&& opt
->len
== 4) {
304 memcpy(&reqaddr
, opt
->data
, 4);
305 } else if (opt
->type
== DHCPV4_OPT_SERVERID
&& opt
->len
== 4) {
306 if (memcmp(opt
->data
, &ifaddr
.sin_addr
, 4))
308 } else if (iface
->filter_class
&& opt
->type
== DHCPV4_OPT_USER_CLASS
) {
309 uint8_t *c
= opt
->data
, *cend
= &opt
->data
[opt
->len
];
310 for (; c
< cend
&& &c
[*c
] < cend
; c
= &c
[1 + *c
]) {
311 size_t elen
= strlen(iface
->filter_class
);
312 if (*c
== elen
&& !memcmp(&c
[1], iface
->filter_class
, elen
))
313 return; // Ignore from homenet
318 if (reqmsg
!= DHCPV4_MSG_DISCOVER
&& reqmsg
!= DHCPV4_MSG_REQUEST
&&
319 reqmsg
!= DHCPV4_MSG_INFORM
&& reqmsg
!= DHCPV4_MSG_DECLINE
&&
320 reqmsg
!= DHCPV4_MSG_RELEASE
)
323 struct dhcpv4_assignment
*lease
= NULL
;
324 if (reqmsg
!= DHCPV4_MSG_INFORM
)
325 lease
= dhcpv4_lease(iface
, reqmsg
, req
->chaddr
, reqaddr
, hostname
);
328 if (reqmsg
== DHCPV4_MSG_REQUEST
)
329 msg
= DHCPV4_MSG_NAK
;
330 else if (reqmsg
== DHCPV4_MSG_DISCOVER
)
332 } else if (reqmsg
== DHCPV4_MSG_DISCOVER
) {
333 msg
= DHCPV4_MSG_OFFER
;
334 } else if (reqmsg
== DHCPV4_MSG_REQUEST
&& reqaddr
.s_addr
&&
335 reqaddr
.s_addr
!= htonl(lease
->addr
)) {
336 msg
= DHCPV4_MSG_NAK
;
338 * DHCP client requested an IP which we can't offer to him. Probably the
339 * client changed the network. The reply type is set to DHCPV4_MSG_NAK,
340 * because the client should not use that IP.
342 * For modern devices we build an answer that includes a valid IP, like
343 * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to
344 * perform additional DHCP round trips.
349 if (reqmsg
== DHCPV4_MSG_DECLINE
|| reqmsg
== DHCPV4_MSG_RELEASE
)
352 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_MESSAGE
, 1, &msg
);
353 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_SERVERID
, 4, &ifaddr
.sin_addr
);
356 reply
.yiaddr
.s_addr
= htonl(lease
->addr
);
358 uint32_t val
= htonl(iface
->dhcpv4_leasetime
);
359 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_LEASETIME
, 4, &val
);
361 val
= htonl(500 * iface
->dhcpv4_leasetime
/ 1000);
362 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_RENEW
, 4, &val
);
364 val
= htonl(875 * iface
->dhcpv4_leasetime
/ 1000);
365 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_REBIND
, 4, &val
);
367 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_NETMASK
, 4, &ifnetmask
.sin_addr
);
369 if (lease
->hostname
[0])
370 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_HOSTNAME
,
371 strlen(lease
->hostname
), lease
->hostname
);
373 if (!ioctl(sock
, SIOCGIFBRDADDR
, &ifr
)) {
374 struct sockaddr_in
*ina
= (struct sockaddr_in
*)&ifr
.ifr_broadaddr
;
375 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_BROADCAST
, 4, &ina
->sin_addr
);
379 if (!ioctl(sock
, SIOCGIFMTU
, &ifr
)) {
380 uint16_t mtu
= htons(ifr
.ifr_mtu
);
381 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_MTU
, 2, &mtu
);
384 if (iface
->search
&& iface
->search_len
<= 255) {
385 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_SEARCH_DOMAIN
,
386 iface
->search_len
, iface
->search
);
387 } else if (!res_init() && _res
.dnsrch
[0] && _res
.dnsrch
[0][0]) {
388 uint8_t search_buf
[256];
389 int len
= dn_comp(_res
.dnsrch
[0], search_buf
,
390 sizeof(search_buf
), NULL
, NULL
);
392 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_SEARCH_DOMAIN
,
396 if (iface
->dhcpv4_router_cnt
== 0)
397 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_ROUTER
, 4, &ifaddr
.sin_addr
);
399 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_ROUTER
,
400 4 * iface
->dhcpv4_router_cnt
, iface
->dhcpv4_router
);
403 if (iface
->dhcpv4_dns_cnt
== 0)
404 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_DNSSERVER
, 4, &ifaddr
.sin_addr
);
406 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_DNSSERVER
,
407 4 * iface
->dhcpv4_dns_cnt
, iface
->dhcpv4_dns
);
410 dhcpv4_put(&reply
, &cookie
, DHCPV4_OPT_END
, 0, NULL
);
412 struct sockaddr_in dest
= *((struct sockaddr_in
*)addr
);
413 if (req
->giaddr
.s_addr
) {
414 dest
.sin_addr
= req
->giaddr
;
415 dest
.sin_port
= htons(DHCPV4_SERVER_PORT
);
416 } else if (req
->ciaddr
.s_addr
&& req
->ciaddr
.s_addr
!= dest
.sin_addr
.s_addr
) {
417 dest
.sin_addr
= req
->ciaddr
;
418 dest
.sin_port
= htons(DHCPV4_CLIENT_PORT
);
419 } else if ((ntohs(req
->flags
) & DHCPV4_FLAG_BROADCAST
) ||
420 req
->hlen
!= reply
.hlen
|| !reply
.yiaddr
.s_addr
) {
421 dest
.sin_addr
.s_addr
= INADDR_BROADCAST
;
422 dest
.sin_port
= htons(DHCPV4_CLIENT_PORT
);
424 dest
.sin_addr
= reply
.yiaddr
;
425 dest
.sin_port
= htons(DHCPV4_CLIENT_PORT
);
427 struct arpreq arp
= {.arp_flags
= ATF_COM
};
428 memcpy(arp
.arp_ha
.sa_data
, req
->chaddr
, 6);
429 memcpy(&arp
.arp_pa
, &dest
, sizeof(arp
.arp_pa
));
430 memcpy(arp
.arp_dev
, iface
->ifname
, sizeof(arp
.arp_dev
));
431 ioctl(sock
, SIOCSARP
, &arp
);
434 sendto(sock
, &reply
, sizeof(reply
), MSG_DONTWAIT
,
435 (struct sockaddr
*)&dest
, sizeof(dest
));
439 static bool dhcpv4_assign(struct interface
*iface
,
440 struct dhcpv4_assignment
*assign
, uint32_t raddr
)
442 const unsigned tries
= 10;
443 uint32_t start
= ntohl(iface
->dhcpv4_start
.s_addr
);
444 uint32_t end
= ntohl(iface
->dhcpv4_end
.s_addr
);
445 uint32_t count
= end
- start
+ 1;
447 // Seed RNG with checksum of DUID
449 for (size_t i
= 0; i
< sizeof(assign
->hwaddr
); ++i
)
450 seed
+= assign
->hwaddr
[i
];
453 // Try to assign up to 100x
454 for (unsigned i
= 0; i
< tries
; ++i
) {
455 uint32_t try = (((uint32_t)rand()) % count
) + start
;
456 if (i
== 0 && raddr
>= start
&& raddr
<= end
)
458 else if (i
== tries
- 1)
461 if (list_empty(&iface
->dhcpv4_assignments
)) {
463 list_add(&assign
->head
, &iface
->dhcpv4_assignments
);
467 struct dhcpv4_assignment
*c
;
468 list_for_each_entry(c
, &iface
->dhcpv4_assignments
, head
) {
471 list_add_tail(&assign
->head
, &c
->head
);
473 } else if (c
->addr
== try) {
486 static struct dhcpv4_assignment
* dhcpv4_lease(struct interface
*iface
,
487 enum dhcpv4_msg msg
, const uint8_t *mac
, struct in_addr reqaddr
,
488 const char *hostname
)
490 struct dhcpv4_assignment
*lease
= NULL
;
491 uint32_t raddr
= ntohl(reqaddr
.s_addr
);
492 time_t now
= odhcpd_time();
494 struct dhcpv4_assignment
*c
, *n
, *a
= NULL
;
495 list_for_each_entry_safe(c
, n
, &iface
->dhcpv4_assignments
, head
) {
496 if (!memcmp(c
->hwaddr
, mac
, 6)) {
498 if (c
->addr
== raddr
)
500 } else if (c
->valid_until
< now
) {
506 if (msg
== DHCPV4_MSG_DISCOVER
|| msg
== DHCPV4_MSG_REQUEST
) {
508 size_t hostlen
= strlen(hostname
) + 1;
510 if (!a
&& !iface
->no_dynamic_dhcp
) { // Create new binding
511 a
= calloc(1, sizeof(*a
) + hostlen
);
513 syslog(LOG_ERR
, "Failed to calloc binding on interface %s", iface
->ifname
);
516 memcpy(a
->hwaddr
, mac
, sizeof(a
->hwaddr
));
517 memcpy(a
->hostname
, hostname
, hostlen
);
519 assigned
= dhcpv4_assign(iface
, a
, raddr
);
522 if (assigned
&& !a
->hostname
[0] && hostname
) {
523 a
= realloc(a
, sizeof(*a
) + hostlen
);
525 syslog(LOG_ERR
, "Failed to realloc binding on interface %s", iface
->ifname
);
528 memcpy(a
->hostname
, hostname
, hostlen
);
531 a
->head
.next
->prev
= &a
->head
;
532 a
->head
.prev
->next
= &a
->head
;
535 // Was only a solicitation: mark binding for removal
536 if (assigned
&& a
->valid_until
< now
) {
537 a
->valid_until
= (msg
== DHCPV4_MSG_DISCOVER
) ? 0 :
538 (now
+ iface
->dhcpv4_leasetime
);
539 } else if (!assigned
&& a
) { // Cleanup failed assignment
546 } else if (msg
== DHCPV4_MSG_RELEASE
) {
550 } else if (msg
== DHCPV4_MSG_DECLINE
) {
551 memset(a
->hwaddr
, 0, sizeof(a
->hwaddr
));
552 a
->valid_until
= now
+ 3600; // Block address for 1h
555 dhcpv6_write_statefile();