router: use enum to specify order and index of iov struct
[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 #include <arpa/inet.h>
22
23 #include "odhcpd.h"
24 #include "dhcpv6.h"
25
26
27 static void relay_client_request(struct sockaddr_in6 *source,
28                 const void *data, size_t len, struct interface *iface);
29 static void relay_server_response(uint8_t *data, size_t len);
30
31 static void handle_dhcpv6(void *addr, void *data, size_t len,
32                 struct interface *iface, void *dest);
33 static void handle_client_request(void *addr, void *data, size_t len,
34                 struct interface *iface, void *dest_addr);
35
36
37
38 // Create socket and register events
39 int init_dhcpv6(void)
40 {
41         dhcpv6_ia_init();
42         return 0;
43 }
44
45
46 int setup_dhcpv6_interface(struct interface *iface, bool enable)
47 {
48         if (iface->dhcpv6_event.uloop.fd > 0) {
49                 uloop_fd_delete(&iface->dhcpv6_event.uloop);
50                 close(iface->dhcpv6_event.uloop.fd);
51                 iface->dhcpv6_event.uloop.fd = -1;
52         }
53
54         // Configure multicast settings
55         if (enable && iface->dhcpv6) {
56                 int sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
57                 if (sock < 0) {
58                         syslog(LOG_ERR, "Failed to create DHCPv6 server socket: %s",
59                                         strerror(errno));
60                         return -1;
61                 }
62
63                 // Basic IPv6 configuration
64                 setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, iface->ifname, strlen(iface->ifname));
65
66                 int val = 1;
67                 setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
68                 setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
69                 setsockopt(sock, IPPROTO_IPV6, IPV6_RECVPKTINFO, &val, sizeof(val));
70
71                 val = DHCPV6_HOP_COUNT_LIMIT;
72                 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &val, sizeof(val));
73
74                 val = 0;
75                 setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &val, sizeof(val));
76
77                 struct sockaddr_in6 bind_addr = {AF_INET6, htons(DHCPV6_SERVER_PORT),
78                                         0, IN6ADDR_ANY_INIT, 0};
79
80                 if (bind(sock, (struct sockaddr*)&bind_addr, sizeof(bind_addr))) {
81                         syslog(LOG_ERR, "Failed to open DHCPv6 server socket: %s",
82                                         strerror(errno));
83                         return -1;
84                 }
85
86                 struct ipv6_mreq relay = {ALL_DHCPV6_RELAYS, iface->ifindex};
87                 struct ipv6_mreq server = {ALL_DHCPV6_SERVERS, iface->ifindex};
88                 setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &relay, sizeof(relay));
89
90                 if (iface->dhcpv6 == RELAYD_SERVER)
91                         setsockopt(sock, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &server, sizeof(server));
92
93                 if (iface->dhcpv6 != RELAYD_RELAY || !iface->master)
94                         ndp_rqs_addr6_dump();
95
96                 iface->dhcpv6_event.uloop.fd = sock;
97                 iface->dhcpv6_event.handle_dgram = handle_dhcpv6;
98                 odhcpd_register(&iface->dhcpv6_event);
99         }
100
101         return setup_dhcpv6_ia_interface(iface, enable);
102 }
103
104 enum {
105         IOV_NESTED = 0,
106         IOV_DEST,
107         IOV_MAXRT,
108 #define IOV_STAT IOV_MAXRT
109         IOV_DNS,
110         IOV_DNS_ADDR,
111         IOV_SEARCH,
112         IOV_SEARCH_DOMAIN,
113         IOV_PDBUF,
114 #define IOV_REFRESH IOV_PDBUF
115         IOV_CERID,
116         IOV_DHCPV6_RAW,
117         IOV_RELAY_MSG,
118         IOV_TOTAL
119 };
120
121 static void handle_nested_message(uint8_t *data, size_t len,
122                 uint8_t **opts, uint8_t **end, struct iovec iov[IOV_TOTAL - 1])
123 {
124         struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data;
125         if (iov[IOV_NESTED].iov_base == NULL) {
126                 iov[IOV_NESTED].iov_base = data;
127                 iov[IOV_NESTED].iov_len = len;
128         }
129
130         if (len < sizeof(struct dhcpv6_client_header))
131                 return;
132
133         if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW) {
134                 iov[IOV_NESTED].iov_len = data - (uint8_t*)iov[IOV_NESTED].iov_base;
135                 struct dhcpv6_client_header *hdr = (void*)data;
136                 *opts = (uint8_t*)&hdr[1];
137                 *end = data + len;
138                 return;
139         }
140
141         uint16_t otype, olen;
142         uint8_t *odata;
143         dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) {
144                 if (otype == DHCPV6_OPT_RELAY_MSG) {
145                         iov[IOV_RELAY_MSG].iov_base = odata + olen;
146                         iov[IOV_RELAY_MSG].iov_len = (((uint8_t*)iov[IOV_NESTED].iov_base) + 
147                                         iov[IOV_NESTED].iov_len) - (odata + olen);
148                         handle_nested_message(odata, olen, opts, end, iov);
149                         return;
150                 }
151         }
152 }
153
154
155 static void update_nested_message(uint8_t *data, size_t len, ssize_t pdiff)
156 {
157         struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data;
158         if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW)
159                 return;
160
161         hdr->msg_type = DHCPV6_MSG_RELAY_REPL;
162
163         uint16_t otype, olen;
164         uint8_t *odata;
165         dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) {
166                 if (otype == DHCPV6_OPT_RELAY_MSG) {
167                         olen += pdiff;
168                         odata[-2] = (olen >> 8) & 0xff;
169                         odata[-1] = olen & 0xff;
170                         update_nested_message(odata, olen - pdiff, pdiff);
171                         return;
172                 }
173         }
174 }
175
176 // Simple DHCPv6-server for information requests
177 static void handle_client_request(void *addr, void *data, size_t len,
178                 struct interface *iface, void *dest_addr)
179 {
180         struct dhcpv6_client_header *hdr = data;
181
182         if (len < sizeof(*hdr))
183                 return;
184
185         syslog(LOG_NOTICE, "Got DHCPv6 request");
186
187         // Construct reply message
188         struct __attribute__((packed)) {
189                 uint8_t msg_type;
190                 uint8_t tr_id[3];
191                 uint16_t serverid_type;
192                 uint16_t serverid_length;
193                 uint16_t duid_type;
194                 uint16_t hardware_type;
195                 uint8_t mac[6];
196                 uint16_t clientid_type;
197                 uint16_t clientid_length;
198                 uint8_t clientid_buf[130];
199         } dest = {
200                 .msg_type = DHCPV6_MSG_REPLY,
201                 .serverid_type = htons(DHCPV6_OPT_SERVERID),
202                 .serverid_length = htons(10),
203                 .duid_type = htons(3),
204                 .hardware_type = htons(1),
205                 .clientid_type = htons(DHCPV6_OPT_CLIENTID),
206                 .clientid_buf = {0}
207         };
208         odhcpd_get_mac(iface, dest.mac);
209
210         struct __attribute__((packed)) {
211                 uint16_t type;
212                 uint16_t len;
213                 uint32_t value;
214         } maxrt = {htons(DHCPV6_OPT_SOL_MAX_RT), htons(sizeof(maxrt) - 4),
215                         htonl(60)};
216
217         struct __attribute__((packed)) {
218                 uint16_t type;
219                 uint16_t len;
220                 uint16_t value;
221         } stat = {htons(DHCPV6_OPT_STATUS), htons(sizeof(stat) - 4),
222                         htons(DHCPV6_STATUS_USEMULTICAST)};
223
224         struct __attribute__((packed)) {
225                 uint16_t type;
226                 uint16_t len;
227                 uint32_t value;
228         } refresh = {htons(DHCPV6_OPT_INFO_REFRESH), htons(sizeof(uint32_t)),
229                         htonl(600)};
230
231         struct in6_addr dns_addr, *dns_addr_ptr = iface->dns;
232         size_t dns_cnt = iface->dns_cnt;
233
234         if ((dns_cnt == 0) &&
235                 !odhcpd_get_interface_dns_addr(iface, &dns_addr)) {
236                 dns_addr_ptr = &dns_addr;
237                 dns_cnt = 1;
238         }
239
240         struct {
241                 uint16_t type;
242                 uint16_t len;
243         } dns = {htons(DHCPV6_OPT_DNS_SERVERS), htons(dns_cnt * sizeof(*dns_addr_ptr))};
244
245
246
247         // DNS Search options
248         uint8_t search_buf[256], *search_domain = iface->search;
249         size_t search_len = iface->search_len;
250
251         if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
252                 int len = dn_comp(_res.dnsrch[0], search_buf,
253                                 sizeof(search_buf), NULL, NULL);
254                 if (len > 0) {
255                         search_domain = search_buf;
256                         search_len = len;
257                 }
258         }
259
260         struct {
261                 uint16_t type;
262                 uint16_t len;
263         } search = {htons(DHCPV6_OPT_DNS_DOMAIN), htons(search_len)};
264
265
266         struct dhcpv6_cer_id cerid = {
267 #ifdef EXT_CER_ID
268                 .type = htons(EXT_CER_ID),
269 #endif
270                 .len = htons(36),
271                 .addr = iface->dhcpv6_pd_cer,
272         };
273
274
275         uint8_t pdbuf[512];
276         struct iovec iov[IOV_TOTAL] = {
277                 [IOV_NESTED] = {NULL, 0},
278                 [IOV_DEST] = {&dest, (uint8_t*)&dest.clientid_type - (uint8_t*)&dest},
279                 [IOV_MAXRT] = {&maxrt, sizeof(maxrt)},
280                 [IOV_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
281                 [IOV_DNS_ADDR] = {dns_addr_ptr, dns_cnt * sizeof(*dns_addr_ptr)},
282                 [IOV_SEARCH] = {&search, (search_len) ? sizeof(search) : 0},
283                 [IOV_SEARCH_DOMAIN] = {search_domain, search_len},
284                 [IOV_PDBUF] = {pdbuf, 0},
285                 [IOV_CERID] = {&cerid, 0},
286                 [IOV_DHCPV6_RAW] = {iface->dhcpv6_raw, iface->dhcpv6_raw_len},
287                 [IOV_RELAY_MSG] = {NULL, 0}
288         };
289
290         uint8_t *opts = (uint8_t*)&hdr[1], *opts_end = (uint8_t*)data + len;
291         if (hdr->msg_type == DHCPV6_MSG_RELAY_FORW)
292                 handle_nested_message(data, len, &opts, &opts_end, iov);
293
294         memcpy(dest.tr_id, &opts[-3], sizeof(dest.tr_id));
295
296         if (opts[-4] == DHCPV6_MSG_ADVERTISE || opts[-4] == DHCPV6_MSG_REPLY || opts[-4] == DHCPV6_MSG_RELAY_REPL)
297                 return;
298
299         if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 &&
300                 (opts[-4] == DHCPV6_MSG_SOLICIT || opts[-4] == DHCPV6_MSG_CONFIRM ||
301                  opts[-4] == DHCPV6_MSG_REBIND || opts[-4] == DHCPV6_MSG_INFORMATION_REQUEST))
302                 return;
303
304         if (opts[-4] == DHCPV6_MSG_SOLICIT) {
305                 dest.msg_type = DHCPV6_MSG_ADVERTISE;
306         } else if (opts[-4] == DHCPV6_MSG_INFORMATION_REQUEST) {
307                 iov[IOV_REFRESH].iov_base = &refresh;
308                 iov[IOV_REFRESH].iov_len = sizeof(refresh);
309
310                 // Return inf max rt option in reply to information request
311                 maxrt.type = htons(DHCPV6_OPT_INF_MAX_RT);
312         }
313
314         // Go through options and find what we need
315         uint16_t otype, olen;
316         uint8_t *odata;
317         dhcpv6_for_each_option(opts, opts_end, otype, olen, odata) {
318                 if (otype == DHCPV6_OPT_CLIENTID && olen <= 130) {
319                         dest.clientid_length = htons(olen);
320                         memcpy(dest.clientid_buf, odata, olen);
321                         iov[IOV_DEST].iov_len += 4 + olen;
322                 } else if (otype == DHCPV6_OPT_SERVERID) {
323                         if (olen != ntohs(dest.serverid_length) ||
324                                         memcmp(odata, &dest.duid_type, olen))
325                                 return; // Not for us
326                 } else if (iface->filter_class && otype == DHCPV6_OPT_USER_CLASS) {
327                         uint8_t *c = odata, *cend = &odata[olen];
328                         for (; &c[2] <= cend && &c[2 + (c[0] << 8) + c[1]] <= cend; c = &c[2 + (c[0] << 8) + c[1]]) {
329                                 size_t elen = strlen(iface->filter_class);
330                                 if (((((size_t)c[0]) << 8) | c[1]) == elen && !memcmp(&c[2], iface->filter_class, elen))
331                                         return; // Ignore from homenet
332                         }
333                 } else if (otype == DHCPV6_OPT_IA_PD) {
334 #ifdef EXT_CER_ID
335                         iov[IOV_CERID].iov_len = sizeof(cerid);
336
337                         if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr)) {
338                                 struct odhcpd_ipaddr *addrs;
339                                 ssize_t len = odhcpd_get_interface_addresses(0, &addrs);
340
341                                 for (ssize_t i = 0; i < len; ++i)
342                                         if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr)
343                                                         || memcmp(&addrs[i].addr, &cerid.addr, sizeof(cerid.addr)) < 0)
344                                                 cerid.addr = addrs[i].addr;
345
346                                 free(addrs);
347                         }
348 #endif
349                 }
350         }
351
352         if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 &&
353                 (opts[-4] == DHCPV6_MSG_REQUEST || opts[-4] == DHCPV6_MSG_RENEW ||
354                  opts[-4] == DHCPV6_MSG_RELEASE || opts[-4] == DHCPV6_MSG_DECLINE)) {
355                 iov[IOV_STAT].iov_base = &stat;
356                 iov[IOV_STAT].iov_len = sizeof(stat);
357
358                 for (ssize_t i = IOV_STAT + 1; i < IOV_TOTAL; ++i)
359                         iov[i].iov_len = 0;
360
361                 odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface);
362                 return;
363         }
364
365         if (opts[-4] != DHCPV6_MSG_INFORMATION_REQUEST) {
366                 ssize_t ialen = dhcpv6_handle_ia(pdbuf, sizeof(pdbuf), iface, addr, &opts[-4], opts_end);
367                 iov[IOV_PDBUF].iov_len = ialen;
368                 if (ialen < 0 || (ialen == 0 && (opts[-4] == DHCPV6_MSG_REBIND || opts[-4] == DHCPV6_MSG_CONFIRM)))
369                         return;
370         }
371
372         if (iov[IOV_NESTED].iov_len > 0) // Update length
373                 update_nested_message(data, len, iov[IOV_DEST].iov_len + iov[IOV_MAXRT].iov_len +
374                                 iov[IOV_DNS].iov_len + iov[IOV_DNS_ADDR].iov_len +
375                                 iov[IOV_SEARCH].iov_len + iov[IOV_SEARCH_DOMAIN].iov_len +
376                                 iov[IOV_PDBUF].iov_len + iov[IOV_CERID].iov_len +
377                                 iov[IOV_DHCPV6_RAW].iov_len - (4 + opts_end - opts));
378
379         odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface);
380 }
381
382
383 // Central DHCPv6-relay handler
384 static void handle_dhcpv6(void *addr, void *data, size_t len,
385                 struct interface *iface, void *dest_addr)
386 {
387         if (iface->dhcpv6 == RELAYD_SERVER) {
388                 handle_client_request(addr, data, len, iface, dest_addr);
389         } else if (iface->dhcpv6 == RELAYD_RELAY) {
390                 if (iface->master)
391                         relay_server_response(data, len);
392                 else
393                         relay_client_request(addr, data, len, iface);
394         }
395 }
396
397
398 // Relay server response (regular relay server handling)
399 static void relay_server_response(uint8_t *data, size_t len)
400 {
401         // Information we need to gather
402         uint8_t *payload_data = NULL;
403         size_t payload_len = 0;
404         int32_t ifaceidx = 0;
405         struct sockaddr_in6 target = {AF_INET6, htons(DHCPV6_CLIENT_PORT),
406                 0, IN6ADDR_ANY_INIT, 0};
407
408         syslog(LOG_NOTICE, "Got a DHCPv6-reply");
409
410         int otype, olen;
411         uint8_t *odata, *end = data + len;
412
413         // Relay DHCPv6 reply from server to client
414         struct dhcpv6_relay_header *h = (void*)data;
415         if (len < sizeof(*h) || h->msg_type != DHCPV6_MSG_RELAY_REPL)
416                 return;
417
418         memcpy(&target.sin6_addr, &h->peer_address,
419                         sizeof(struct in6_addr));
420
421         // Go through options and find what we need
422         dhcpv6_for_each_option(h->options, end, otype, olen, odata) {
423                 if (otype == DHCPV6_OPT_INTERFACE_ID
424                                 && olen == sizeof(ifaceidx)) {
425                         memcpy(&ifaceidx, odata, sizeof(ifaceidx));
426                 } else if (otype == DHCPV6_OPT_RELAY_MSG) {
427                         payload_data = odata;
428                         payload_len = olen;
429                 }
430         }
431
432         // Invalid interface-id or basic payload
433         struct interface *iface = odhcpd_get_interface_by_index(ifaceidx);
434         if (!iface || iface->master || !payload_data || payload_len < 4)
435                 return;
436
437         bool is_authenticated = false;
438         struct in6_addr *dns_ptr = NULL;
439         size_t dns_count = 0;
440
441         // If the payload is relay-reply we have to send to the server port
442         if (payload_data[0] == DHCPV6_MSG_RELAY_REPL) {
443                 target.sin6_port = htons(DHCPV6_SERVER_PORT);
444         } else { // Go through the payload data
445                 struct dhcpv6_client_header *h = (void*)payload_data;
446                 end = payload_data + payload_len;
447
448                 dhcpv6_for_each_option(&h[1], end, otype, olen, odata) {
449                         if (otype == DHCPV6_OPT_DNS_SERVERS && olen >= 16) {
450                                 dns_ptr = (struct in6_addr*)odata;
451                                 dns_count = olen / 16;
452                         } else if (otype == DHCPV6_OPT_AUTH) {
453                                 is_authenticated = true;
454                         }
455                 }
456         }
457
458         // Rewrite DNS servers if requested
459         if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
460                 if (is_authenticated)
461                         return; // Impossible to rewrite
462
463                 const struct in6_addr *rewrite = iface->dns;
464                 struct in6_addr addr;
465                 size_t rewrite_cnt = iface->dns_cnt;
466
467                 if (rewrite_cnt == 0) {
468                         if (odhcpd_get_interface_dns_addr(iface, &addr))
469                                 return; // Unable to get interface address
470
471                         rewrite = &addr;
472                         rewrite_cnt = 1;
473                 }
474
475                 // Copy over any other addresses
476                 for (size_t i = 0; i < dns_count; ++i) {
477                         size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
478                         memcpy(&dns_ptr[i], &rewrite[j], sizeof(*rewrite));
479                 }
480         }
481
482         struct iovec iov = {payload_data, payload_len};
483         odhcpd_send(iface->dhcpv6_event.uloop.fd, &target, &iov, 1, iface);
484 }
485
486
487 // Relay client request (regular DHCPv6-relay)
488 static void relay_client_request(struct sockaddr_in6 *source,
489                 const void *data, size_t len, struct interface *iface)
490 {
491         struct interface *master = odhcpd_get_master_interface();
492         const struct dhcpv6_relay_header *h = data;
493         if (!master || master->dhcpv6 != RELAYD_RELAY ||
494                         h->msg_type == DHCPV6_MSG_RELAY_REPL ||
495                         h->msg_type == DHCPV6_MSG_RECONFIGURE ||
496                         h->msg_type == DHCPV6_MSG_REPLY ||
497                         h->msg_type == DHCPV6_MSG_ADVERTISE)
498                 return; // Invalid message types for client
499
500         syslog(LOG_NOTICE, "Got a DHCPv6-request");
501
502         // Construct our forwarding envelope
503         struct dhcpv6_relay_forward_envelope hdr = {
504                 .msg_type = DHCPV6_MSG_RELAY_FORW,
505                 .hop_count = 0,
506                 .interface_id_type = htons(DHCPV6_OPT_INTERFACE_ID),
507                 .interface_id_len = htons(sizeof(uint32_t)),
508                 .relay_message_type = htons(DHCPV6_OPT_RELAY_MSG),
509                 .relay_message_len = htons(len),
510         };
511
512         if (h->msg_type == DHCPV6_MSG_RELAY_FORW) { // handle relay-forward
513                 if (h->hop_count >= DHCPV6_HOP_COUNT_LIMIT)
514                         return; // Invalid hop count
515                 else
516                         hdr.hop_count = h->hop_count + 1;
517         }
518
519         // use memcpy here as the destination fields are unaligned
520         uint32_t ifindex = iface->ifindex;
521         memcpy(&hdr.peer_address, &source->sin6_addr, sizeof(struct in6_addr));
522         memcpy(&hdr.interface_id_data, &ifindex, sizeof(ifindex));
523
524         // Detect public IP of slave interface to use as link-address
525         struct odhcpd_ipaddr *ip = NULL;
526         if (odhcpd_get_interface_addresses(iface->ifindex, &ip) < 1) {
527                 // No suitable address! Is the slave not configured yet?
528                 // Detect public IP of master interface and use it instead
529                 // This is WRONG and probably violates the RFC. However
530                 // otherwise we have a hen and egg problem because the
531                 // slave-interface cannot be auto-configured.
532                 if (odhcpd_get_interface_addresses(master->ifindex, &ip) < 1)
533                         return; // Could not obtain a suitable address
534         }
535         memcpy(&hdr.link_address, &ip[0].addr, sizeof(hdr.link_address));
536         free(ip);
537
538         struct sockaddr_in6 dhcpv6_servers = {AF_INET6,
539                         htons(DHCPV6_SERVER_PORT), 0, ALL_DHCPV6_SERVERS, 0};
540         struct iovec iov[2] = {{&hdr, sizeof(hdr)}, {(void*)data, len}};
541         odhcpd_send(master->dhcpv6_event.uloop.fd, &dhcpv6_servers, iov, 2, master);
542 }