Fix ra_management and ndproxy_routing config overwrite
[project/odhcpd.git] / src / dhcpv6.c
1 /**
2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
3  *
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.
7  *
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.
12  *
13  *
14  */
15
16 #include <errno.h>
17 #include <unistd.h>
18 #include <stddef.h>
19 #include <resolv.h>
20 #include <sys/timerfd.h>
21
22 #include "odhcpd.h"
23 #include "dhcpv6.h"
24
25
26 static void relay_client_request(struct sockaddr_in6 *source,
27                 const void *data, size_t len, struct interface *iface);
28 static void relay_server_response(uint8_t *data, size_t len);
29
30 static void handle_dhcpv6(void *addr, void *data, size_t len,
31                 struct interface *iface);
32 static void handle_client_request(void *addr, void *data, size_t len,
33                 struct interface *iface);
34
35
36
37 // Create socket and register events
38 int init_dhcpv6(void)
39 {
40         dhcpv6_ia_init();
41         return 0;
42 }
43
44
45 int setup_dhcpv6_interface(struct interface *iface, bool enable)
46 {
47         if (iface->dhcpv6_event.uloop.fd > 0) {
48                 uloop_fd_delete(&iface->dhcpv6_event.uloop);
49                 close(iface->dhcpv6_event.uloop.fd);
50                 iface->dhcpv6_event.uloop.fd = -1;
51         }
52
53         // Configure multicast settings
54         if (enable && iface->dhcpv6 && !iface->master) {
55                 int sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
56                 if (sock < 0) {
57                         syslog(LOG_ERR, "Failed to create DHCPv6 server socket: %s",
58                                         strerror(errno));
59                         return -1;
60                 }
61
62                 // Basic IPv6 configuration
63                 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, iface->ifname, strlen(iface->ifname));
64
65                 int val = 1;
66                 setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
67                 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
68                 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
69
70                 val = DHCPV6_HOP_COUNT_LIMIT;
71                 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
72
73                 val = 0;
74                 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
75
76                 struct sockaddr_in6 bind_addr = {AF_INET6, htons(DHCPV6_SERVER_PORT),
77                                         0, IN6ADDR_ANY_INIT, 0};
78
79                 if (bind(sock, (struct sockaddr*)&bind_addr, sizeof(bind_addr))) {
80                         syslog(LOG_ERR, "Failed to open DHCPv6 server socket: %s",
81                                         strerror(errno));
82                         return -1;
83                 }
84
85                 struct ipv6_mreq relay = {ALL_DHCPV6_RELAYS, iface->ifindex};
86                 struct ipv6_mreq server = {ALL_DHCPV6_SERVERS, iface->ifindex};
87                 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &relay, sizeof(relay));
88
89                 if (iface->dhcpv6 == RELAYD_SERVER)
90                         setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &server, sizeof(server));
91
92                 iface->dhcpv6_event.uloop.fd = sock;
93                 iface->dhcpv6_event.handle_dgram = handle_dhcpv6;
94                 odhcpd_register(&iface->dhcpv6_event);
95         }
96
97         return setup_dhcpv6_ia_interface(iface, enable);
98 }
99
100
101 static void handle_nested_message(uint8_t *data, size_t len,
102                 uint8_t **opts, uint8_t **end, struct iovec iov[6])
103 {
104         struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data;
105         if (iov[0].iov_base == NULL) {
106                 iov[0].iov_base = data;
107                 iov[0].iov_len = len;
108         }
109
110         if (len < sizeof(struct dhcpv6_client_header))
111                 return;
112
113         if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW) {
114                 iov[0].iov_len = data - (uint8_t*)iov[0].iov_base;
115                 struct dhcpv6_client_header *hdr = (void*)data;
116                 *opts = (uint8_t*)&hdr[1];
117                 *end = data + len;
118                 return;
119         }
120
121         uint16_t otype, olen;
122         uint8_t *odata;
123         dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) {
124                 if (otype == DHCPV6_OPT_RELAY_MSG) {
125                         iov[7].iov_base = odata + olen;
126                         iov[7].iov_len = (((uint8_t*)iov[0].iov_base) + iov[0].iov_len)
127                                         - (odata + olen);
128                         handle_nested_message(odata, olen, opts, end, iov);
129                         return;
130                 }
131         }
132 }
133
134
135 static void update_nested_message(uint8_t *data, size_t len, ssize_t pdiff)
136 {
137         struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data;
138         if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW)
139                 return;
140
141         hdr->msg_type = DHCPV6_MSG_RELAY_REPL;
142
143         uint16_t otype, olen;
144         uint8_t *odata;
145         dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) {
146                 if (otype == DHCPV6_OPT_RELAY_MSG) {
147                         olen += pdiff;
148                         odata[-2] = (olen >> 8) & 0xff;
149                         odata[-1] = olen & 0xff;
150                         update_nested_message(odata, olen - pdiff, pdiff);
151                         return;
152                 }
153         }
154 }
155
156
157 // Simple DHCPv6-server for information requests
158 static void handle_client_request(void *addr, void *data, size_t len,
159                 struct interface *iface)
160 {
161         struct dhcpv6_client_header *hdr = data;
162         if (len < sizeof(*hdr))
163                 return;
164
165         syslog(LOG_NOTICE, "Got DHCPv6 request");
166
167         // Construct reply message
168         struct __attribute__((packed)) {
169                 uint8_t msg_type;
170                 uint8_t tr_id[3];
171                 uint16_t serverid_type;
172                 uint16_t serverid_length;
173                 uint16_t duid_type;
174                 uint16_t hardware_type;
175                 uint8_t mac[6];
176                 uint16_t clientid_type;
177                 uint16_t clientid_length;
178                 uint8_t clientid_buf[130];
179         } dest = {
180                 .msg_type = DHCPV6_MSG_REPLY,
181                 .serverid_type = htons(DHCPV6_OPT_SERVERID),
182                 .serverid_length = htons(10),
183                 .duid_type = htons(3),
184                 .hardware_type = htons(1),
185                 .clientid_type = htons(DHCPV6_OPT_CLIENTID),
186                 .clientid_buf = {0}
187         };
188         odhcpd_get_mac(iface, dest.mac);
189
190         struct __attribute__((packed)) {
191                 uint16_t type;
192                 uint16_t len;
193                 uint16_t value;
194         } stat = {htons(DHCPV6_OPT_STATUS), htons(sizeof(stat) - 4),
195                         htons(DHCPV6_STATUS_NOADDRSAVAIL)};
196
197         struct __attribute__((packed)) {
198                 uint16_t type;
199                 uint16_t len;
200                 uint32_t value;
201         } refresh = {htons(DHCPV6_OPT_INFO_REFRESH), htons(sizeof(uint32_t)),
202                         htonl(600)};
203
204         struct odhcpd_ipaddr ipaddr;
205         struct in6_addr *dns_addr = iface->dns;
206         size_t dns_cnt = iface->dns_cnt;
207
208         if (dns_cnt == 0 && odhcpd_get_interface_addresses(iface->ifindex, &ipaddr, 1) == 1) {
209                 dns_addr = &ipaddr.addr;
210                 dns_cnt = 1;
211         }
212
213         struct {
214                 uint16_t type;
215                 uint16_t len;
216         } dns = {htons(DHCPV6_OPT_DNS_SERVERS), htons(dns_cnt * sizeof(*dns_addr))};
217
218
219
220         // DNS Search options
221         uint8_t search_buf[256], *search_domain = iface->search;
222         size_t search_len = iface->search_len;
223
224         if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
225                 int len = dn_comp(_res.dnsrch[0], search_buf,
226                                 sizeof(search_buf), NULL, NULL);
227                 if (len > 0) {
228                         search_domain = search_buf;
229                         search_len = len;
230                 }
231         }
232
233         struct {
234                 uint16_t type;
235                 uint16_t len;
236         } search = {htons(DHCPV6_OPT_DNS_DOMAIN), htons(search_len)};
237
238
239
240         uint8_t pdbuf[512];
241         struct iovec iov[] = {{NULL, 0},
242                         {&dest, (uint8_t*)&dest.clientid_type - (uint8_t*)&dest},
243                         {&dns, (dns_cnt) ? sizeof(dns) : 0},
244                         {dns_addr, dns_cnt * sizeof(*dns_addr)},
245                         {&search, (search_len) ? sizeof(search) : 0},
246                         {search_domain, search_len},
247                         {pdbuf, 0},
248                         {NULL, 0}};
249
250         uint8_t *opts = (uint8_t*)&hdr[1], *opts_end = (uint8_t*)data + len;
251         if (hdr->msg_type == DHCPV6_MSG_RELAY_FORW)
252                 handle_nested_message(data, len, &opts, &opts_end, iov);
253
254         memcpy(dest.tr_id, &opts[-3], sizeof(dest.tr_id));
255
256         if (opts[-4] == DHCPV6_MSG_ADVERTISE || opts[-4] == DHCPV6_MSG_REPLY || opts[-4] == DHCPV6_MSG_RELAY_REPL)
257                 return;
258
259         if (opts[-4] == DHCPV6_MSG_SOLICIT) {
260                 dest.msg_type = DHCPV6_MSG_ADVERTISE;
261         } else if (opts[-4] == DHCPV6_MSG_INFORMATION_REQUEST) {
262                 iov[6].iov_base = &refresh;
263                 iov[6].iov_len = sizeof(refresh);
264         }
265
266         // Go through options and find what we need
267         uint16_t otype, olen;
268         uint8_t *odata;
269         dhcpv6_for_each_option(opts, opts_end, otype, olen, odata) {
270                 if (otype == DHCPV6_OPT_CLIENTID && olen <= 130) {
271                         dest.clientid_length = htons(olen);
272                         memcpy(dest.clientid_buf, odata, olen);
273                         iov[1].iov_len += 4 + olen;
274                 } else if (otype == DHCPV6_OPT_SERVERID) {
275                         if (olen != ntohs(dest.serverid_length) ||
276                                         memcmp(odata, &dest.duid_type, olen))
277                                 return; // Not for us
278                 }
279         }
280
281         if (opts[-4] != DHCPV6_MSG_INFORMATION_REQUEST) {
282                 iov[6].iov_len = dhcpv6_handle_ia(pdbuf, sizeof(pdbuf), iface, addr, &opts[-4], opts_end);
283                 if (iov[6].iov_len == 0 && opts[-4] == DHCPV6_MSG_REBIND)
284                         return;
285         }
286
287         if (iov[0].iov_len > 0) // Update length
288                 update_nested_message(data, len, iov[1].iov_len + iov[2].iov_len +
289                                 iov[3].iov_len + iov[4].iov_len + iov[5].iov_len +
290                                 iov[6].iov_len - (4 + opts_end - opts));
291
292         odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface);
293 }
294
295
296 // Central DHCPv6-relay handler
297 static void handle_dhcpv6(void *addr, void *data, size_t len,
298                 struct interface *iface)
299 {
300         if (iface->dhcpv6 == RELAYD_SERVER) {
301                 handle_client_request(addr, data, len, iface);
302         } else if (iface->dhcpv6 == RELAYD_RELAY) {
303                 if (iface->master)
304                         relay_server_response(data, len);
305                 else
306                         relay_client_request(addr, data, len, iface);
307         }
308 }
309
310
311 // Relay server response (regular relay server handling)
312 static void relay_server_response(uint8_t *data, size_t len)
313 {
314         // Information we need to gather
315         uint8_t *payload_data = NULL;
316         size_t payload_len = 0;
317         int32_t ifaceidx = 0;
318         struct sockaddr_in6 target = {AF_INET6, htons(DHCPV6_CLIENT_PORT),
319                 0, IN6ADDR_ANY_INIT, 0};
320
321         syslog(LOG_NOTICE, "Got a DHCPv6-reply");
322
323         int otype, olen;
324         uint8_t *odata, *end = data + len;
325
326         // Relay DHCPv6 reply from server to client
327         struct dhcpv6_relay_header *h = (void*)data;
328         if (len < sizeof(*h) || h->msg_type != DHCPV6_MSG_RELAY_REPL)
329                 return;
330
331         memcpy(&target.sin6_addr, &h->peer_address,
332                         sizeof(struct in6_addr));
333
334         // Go through options and find what we need
335         dhcpv6_for_each_option(h->options, end, otype, olen, odata) {
336                 if (otype == DHCPV6_OPT_INTERFACE_ID
337                                 && olen == sizeof(ifaceidx)) {
338                         memcpy(&ifaceidx, odata, sizeof(ifaceidx));
339                 } else if (otype == DHCPV6_OPT_RELAY_MSG) {
340                         payload_data = odata;
341                         payload_len = olen;
342                 }
343         }
344
345         // Invalid interface-id or basic payload
346         struct interface *iface = odhcpd_get_interface_by_index(ifaceidx);
347         if (!iface || iface->master || !payload_data || payload_len < 4)
348                 return;
349
350         bool is_authenticated = false;
351         struct in6_addr *dns_ptr = NULL;
352         size_t dns_count = 0;
353
354         // If the payload is relay-reply we have to send to the server port
355         if (payload_data[0] == DHCPV6_MSG_RELAY_REPL) {
356                 target.sin6_port = htons(DHCPV6_SERVER_PORT);
357         } else { // Go through the payload data
358                 struct dhcpv6_client_header *h = (void*)payload_data;
359                 end = payload_data + payload_len;
360
361                 dhcpv6_for_each_option(&h[1], end, otype, olen, odata) {
362                         if (otype == DHCPV6_OPT_DNS_SERVERS && olen >= 16) {
363                                 dns_ptr = (struct in6_addr*)odata;
364                                 dns_count = olen / 16;
365                         } else if (otype == DHCPV6_OPT_AUTH) {
366                                 is_authenticated = true;
367                         }
368                 }
369         }
370
371         // Rewrite DNS servers if requested
372         if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
373                 if (is_authenticated)
374                         return; // Impossible to rewrite
375
376                 struct odhcpd_ipaddr ip;
377                 const struct in6_addr *rewrite = iface->dns;
378                 size_t rewrite_cnt = iface->dns_cnt;
379
380                 if (rewrite_cnt == 0) {
381                         if (odhcpd_get_interface_addresses(iface->ifindex, &ip, 1) < 1)
382                                 return; // Unable to get interface address
383
384                         rewrite = &ip.addr;
385                         rewrite_cnt = 1;
386                 }
387
388                 // Copy over any other addresses
389                 for (size_t i = 0; i < dns_count; ++i) {
390                         size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
391                         memcpy(&dns_ptr[i], &rewrite[j], sizeof(*rewrite));
392                 }
393         }
394
395         struct iovec iov = {payload_data, payload_len};
396         odhcpd_send(iface->dhcpv6_event.uloop.fd, &target, &iov, 1, iface);
397 }
398
399
400 // Relay client request (regular DHCPv6-relay)
401 static void relay_client_request(struct sockaddr_in6 *source,
402                 const void *data, size_t len, struct interface *iface)
403 {
404         struct interface *master = odhcpd_get_master_interface();
405         const struct dhcpv6_relay_header *h = data;
406         if (!master || master->dhcpv6 != RELAYD_RELAY ||
407                         h->msg_type == DHCPV6_MSG_RELAY_REPL ||
408                         h->msg_type == DHCPV6_MSG_RECONFIGURE ||
409                         h->msg_type == DHCPV6_MSG_REPLY ||
410                         h->msg_type == DHCPV6_MSG_ADVERTISE)
411                 return; // Invalid message types for client
412
413         syslog(LOG_NOTICE, "Got a DHCPv6-request");
414
415         // Construct our forwarding envelope
416         struct dhcpv6_relay_forward_envelope hdr = {
417                 .msg_type = DHCPV6_MSG_RELAY_FORW,
418                 .hop_count = 0,
419                 .interface_id_type = htons(DHCPV6_OPT_INTERFACE_ID),
420                 .interface_id_len = htons(sizeof(uint32_t)),
421                 .relay_message_type = htons(DHCPV6_OPT_RELAY_MSG),
422                 .relay_message_len = htons(len),
423         };
424
425         if (h->msg_type == DHCPV6_MSG_RELAY_FORW) { // handle relay-forward
426                 if (h->hop_count >= DHCPV6_HOP_COUNT_LIMIT)
427                         return; // Invalid hop count
428                 else
429                         hdr.hop_count = h->hop_count + 1;
430         }
431
432         // use memcpy here as the destination fields are unaligned
433         uint32_t ifindex = iface->ifindex;
434         memcpy(&hdr.peer_address, &source->sin6_addr, sizeof(struct in6_addr));
435         memcpy(&hdr.interface_id_data, &ifindex, sizeof(ifindex));
436
437         // Detect public IP of slave interface to use as link-address
438         struct odhcpd_ipaddr ip;
439         if (odhcpd_get_interface_addresses(iface->ifindex, &ip, 1) < 1) {
440                 // No suitable address! Is the slave not configured yet?
441                 // Detect public IP of master interface and use it instead
442                 // This is WRONG and probably violates the RFC. However
443                 // otherwise we have a hen and egg problem because the
444                 // slave-interface cannot be auto-configured.
445                 if (odhcpd_get_interface_addresses(master->ifindex, &ip, 1) < 1)
446                         return; // Could not obtain a suitable address
447         }
448         memcpy(&hdr.link_address, &ip.addr, sizeof(hdr.link_address));
449
450         struct sockaddr_in6 dhcpv6_servers = {AF_INET6,
451                         htons(DHCPV6_SERVER_PORT), 0, ALL_DHCPV6_SERVERS, 0};
452         struct iovec iov[2] = {{&hdr, sizeof(hdr)}, {(void*)data, len}};
453         odhcpd_send(iface->dhcpv6_event.uloop.fd, &dhcpv6_servers, iov, 2, master);
454 }