src/dhcpv6.c

   1 /**
   2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
   3  * Copyright (C) 2018 Hans Dedecker <dedeckeh@gmail.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License v2 as published by
   7  * the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  *
  15  */
  16
  17 #include <errno.h>
  18 #include <unistd.h>
  19 #include <stddef.h>
  20 #include <resolv.h>
  21 #include <sys/timerfd.h>
  22 #include <arpa/inet.h>
  23
  24 #include <libubox/utils.h>
  25
  26 #include "odhcpd.h"
  27 #include "dhcpv6.h"
  28 #ifdef DHCPV4_SUPPORT
  29 #include "dhcpv4.h"
  30 #endif
  31
  32 static void relay_client_request(struct sockaddr_in6 *source,
  33                 const void *data, size_t len, struct interface *iface);
  34 static void relay_server_response(uint8_t *data, size_t len);
  35
  36 static void handle_dhcpv6(void *addr, void *data, size_t len,
  37                 struct interface *iface, void *dest);
  38 static void handle_client_request(void *addr, void *data, size_t len,
  39                 struct interface *iface, void *dest_addr);
  40
  41
  42 /* Create socket and register events */
  43 int dhcpv6_init(void)
  44 {
  45         return dhcpv6_ia_init();
  46 }
  47
  48 int dhcpv6_setup_interface(struct interface *iface, bool enable)
  49 {
  50         int ret = 0;
  51
  52         enable = enable && (iface->dhcpv6 != MODE_DISABLED);
  53
  54         if (iface->dhcpv6_event.uloop.fd >= 0) {
  55                 uloop_fd_delete(&iface->dhcpv6_event.uloop);
  56                 close(iface->dhcpv6_event.uloop.fd);
  57                 iface->dhcpv6_event.uloop.fd = -1;
  58         }
  59
  60         /* Configure multicast settings */
  61         if (enable) {
  62                 struct sockaddr_in6 bind_addr = {AF_INET6, htons(DHCPV6_SERVER_PORT),
  63                                         0, IN6ADDR_ANY_INIT, 0};
  64                 struct ipv6_mreq mreq;
  65                 int val = 1;
  66
  67                 iface->dhcpv6_event.uloop.fd = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  68                 if (iface->dhcpv6_event.uloop.fd < 0) {
  69                         syslog(LOG_ERR, "socket(AF_INET6): %m");
  70                         ret = -1;
  71                         goto out;
  72                 }
  73
  74                 /* Basic IPv6 configuration */
  75                 if (setsockopt(iface->dhcpv6_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE,
  76                                         iface->ifname, strlen(iface->ifname)) < 0) {
  77                         syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m");
  78                         ret = -1;
  79                         goto out;
  80                 }
  81
  82                 if (setsockopt(iface->dhcpv6_event.uloop.fd, IPPROTO_IPV6, IPV6_V6ONLY,
  83                                         &val, sizeof(val)) < 0) {
  84                         syslog(LOG_ERR, "setsockopt(IPV6_V6ONLY): %m");
  85                         ret = -1;
  86                         goto out;
  87                 }
  88
  89                 if (setsockopt(iface->dhcpv6_event.uloop.fd, SOL_SOCKET, SO_REUSEADDR,
  90                                         &val, sizeof(val)) < 0) {
  91                         syslog(LOG_ERR, "setsockopt(SO_REUSEADDR): %m");
  92                         ret = -1;
  93                         goto out;
  94                 }
  95
  96                 if (setsockopt(iface->dhcpv6_event.uloop.fd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
  97                                         &val, sizeof(val)) < 0) {
  98                         syslog(LOG_ERR, "setsockopt(IPV6_RECVPKTINFO): %m");
  99                         ret = -1;
 100                         goto out;
 101                 }
 102
 103                 val = DHCPV6_HOP_COUNT_LIMIT;
 104                 if (setsockopt(iface->dhcpv6_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
 105                                         &val, sizeof(val)) < 0) {
 106                         syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_HOPS): %m");
 107                         ret = -1;
 108                         goto out;
 109                 }
 110
 111                 val = 0;
 112                 if (setsockopt(iface->dhcpv6_event.uloop.fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP,
 113                                         &val, sizeof(val)) < 0) {
 114                         syslog(LOG_ERR, "setsockopt(IPV6_MULTICAST_LOOP): %m");
 115                         ret = -1;
 116                         goto out;
 117                 }
 118
 119                 if (bind(iface->dhcpv6_event.uloop.fd, (struct sockaddr*)&bind_addr,
 120                                         sizeof(bind_addr)) < 0) {
 121                         syslog(LOG_ERR, "bind(): %m");
 122                         ret = -1;
 123                         goto out;
 124                 }
 125
 126                 memset(&mreq, 0, sizeof(mreq));
 127                 inet_pton(AF_INET6, ALL_DHCPV6_RELAYS, &mreq.ipv6mr_multiaddr);
 128                 mreq.ipv6mr_interface = iface->ifindex;
 129
 130                 if (setsockopt(iface->dhcpv6_event.uloop.fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
 131                                         &mreq, sizeof(mreq)) < 0) {
 132                         syslog(LOG_ERR, "setsockopt(IPV6_ADD_MEMBERSHIP): %m");
 133                         ret = -1;
 134                         goto out;
 135                 }
 136
 137                 if (iface->dhcpv6 == MODE_SERVER) {
 138                         memset(&mreq, 0, sizeof(mreq));
 139                         inet_pton(AF_INET6, ALL_DHCPV6_SERVERS, &mreq.ipv6mr_multiaddr);
 140                         mreq.ipv6mr_interface = iface->ifindex;
 141
 142                         if (setsockopt(iface->dhcpv6_event.uloop.fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP,
 143                                                 &mreq, sizeof(mreq)) < 0) {
 144                                 syslog(LOG_ERR, "setsockopt(IPV6_ADD_MEMBERSHIP): %m");
 145                                 ret = -1;
 146                                 goto out;
 147                         }
 148                 }
 149
 150                 iface->dhcpv6_event.handle_dgram = handle_dhcpv6;
 151                 odhcpd_register(&iface->dhcpv6_event);
 152         }
 153
 154         ret = dhcpv6_ia_setup_interface(iface, enable);
 155
 156 out:
 157         if (ret < 0 && iface->dhcpv6_event.uloop.fd >= 0) {
 158                 close(iface->dhcpv6_event.uloop.fd);
 159                 iface->dhcpv6_event.uloop.fd = -1;
 160         }
 161
 162         return ret;
 163 }
 164
 165 enum {
 166         IOV_NESTED = 0,
 167         IOV_DEST,
 168         IOV_MAXRT,
 169 #define IOV_STAT IOV_MAXRT
 170         IOV_RAPID_COMMIT,
 171         IOV_DNS,
 172         IOV_DNS_ADDR,
 173         IOV_SEARCH,
 174         IOV_SEARCH_DOMAIN,
 175         IOV_PDBUF,
 176 #define IOV_REFRESH IOV_PDBUF
 177         IOV_CERID,
 178         IOV_DHCPV6_RAW,
 179         IOV_NTP,
 180         IOV_NTP_ADDR,
 181         IOV_SNTP,
 182         IOV_SNTP_ADDR,
 183         IOV_RELAY_MSG,
 184         IOV_DHCPV4O6_SERVER,
 185         IOV_TOTAL
 186 };
 187
 188 static void handle_nested_message(uint8_t *data, size_t len,
 189                                   struct dhcpv6_client_header **c_hdr, uint8_t **opts,
 190                                   uint8_t **end, struct iovec iov[IOV_TOTAL])
 191 {
 192         struct dhcpv6_relay_header *r_hdr = (struct dhcpv6_relay_header *)data;
 193         uint16_t otype, olen;
 194         uint8_t *odata;
 195
 196         if (iov[IOV_NESTED].iov_base == NULL) {
 197                 iov[IOV_NESTED].iov_base = data;
 198                 iov[IOV_NESTED].iov_len = len;
 199         }
 200
 201         if (len < sizeof(struct dhcpv6_client_header))
 202                 return;
 203
 204         if (r_hdr->msg_type != DHCPV6_MSG_RELAY_FORW) {
 205                 iov[IOV_NESTED].iov_len = data - (uint8_t *)iov[IOV_NESTED].iov_base;
 206                 *c_hdr = (void *)data;
 207                 *opts = (uint8_t *)&(*c_hdr)[1];
 208                 *end = data + len;
 209                 return;
 210         }
 211
 212         dhcpv6_for_each_option(r_hdr->options, data + len, otype, olen, odata) {
 213                 if (otype == DHCPV6_OPT_RELAY_MSG) {
 214                         iov[IOV_RELAY_MSG].iov_base = odata + olen;
 215                         iov[IOV_RELAY_MSG].iov_len = (((uint8_t *)iov[IOV_NESTED].iov_base) +
 216                                         iov[IOV_NESTED].iov_len) - (odata + olen);
 217                         handle_nested_message(odata, olen, c_hdr, opts, end, iov);
 218                         return;
 219                 }
 220         }
 221 }
 222
 223
 224 static void update_nested_message(uint8_t *data, size_t len, ssize_t pdiff)
 225 {
 226         struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data;
 227         if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW)
 228                 return;
 229
 230         hdr->msg_type = DHCPV6_MSG_RELAY_REPL;
 231
 232         uint16_t otype, olen;
 233         uint8_t *odata;
 234         dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) {
 235                 if (otype == DHCPV6_OPT_RELAY_MSG) {
 236                         olen += pdiff;
 237                         odata[-2] = (olen >> 8) & 0xff;
 238                         odata[-1] = olen & 0xff;
 239                         update_nested_message(odata, olen - pdiff, pdiff);
 240                         return;
 241                 }
 242         }
 243 }
 244
 245 #ifdef DHCPV4_SUPPORT
 246
 247 struct dhcpv4_msg_data {
 248         uint8_t *msg;
 249         size_t maxsize;
 250         ssize_t len;
 251 };
 252
 253 static int send_reply(_unused const void *buf, size_t len,
 254                       _unused const struct sockaddr *dest, _unused socklen_t dest_len,
 255                       _unused void *opaque)
 256 {
 257         struct dhcpv4_msg_data *reply = opaque;
 258
 259         if (len > reply->maxsize) {
 260                 syslog(LOG_ERR, "4o6: reply too large, %zu > %zu", len, reply->maxsize);
 261                 reply->len = -1;
 262         } else {
 263                 memcpy(reply->msg, buf, len);
 264                 reply->len = len;
 265         }
 266
 267         return reply->len;
 268 }
 269
 270 static ssize_t dhcpv6_4o6_query(uint8_t *buf, size_t buflen,
 271                                 struct interface *iface,
 272                                 const struct sockaddr_in6 *addr,
 273                                 const void *data, const uint8_t *end)
 274 {
 275         const struct dhcpv6_client_header *hdr = data;
 276         uint16_t otype, olen, msgv4_len = 0;
 277         uint8_t *msgv4_data = NULL;
 278         uint8_t *start = (uint8_t *)&hdr[1], *odata;
 279         struct sockaddr_in addrv4;
 280         struct dhcpv4_msg_data reply = { .msg = buf, .maxsize = buflen, .len = -1 };
 281
 282         dhcpv6_for_each_option(start, end, otype, olen, odata) {
 283                 if (otype == DHCPV6_OPT_DHCPV4_MSG) {
 284                         msgv4_data = odata;
 285                         msgv4_len = olen;
 286                 }
 287         }
 288
 289         if (!msgv4_data || msgv4_len == 0) {
 290                 syslog(LOG_ERR, "4o6: missing DHCPv4 message option (%d)", DHCPV6_OPT_DHCPV4_MSG);
 291                 return -1;
 292         }
 293
 294         // Dummy IPv4 address
 295         memset(&addrv4, 0, sizeof(addrv4));
 296         addrv4.sin_family = AF_INET;
 297         addrv4.sin_addr.s_addr = INADDR_ANY;
 298         addrv4.sin_port = htons(DHCPV4_CLIENT_PORT);
 299
 300         dhcpv4_handle_msg(&addrv4, msgv4_data, msgv4_len,
 301                           iface, NULL, send_reply, &reply);
 302
 303         return reply.len;
 304 }
 305 #endif  /* DHCPV4_SUPPORT */
 306
 307 /* Simple DHCPv6-server for information requests */
 308 static void handle_client_request(void *addr, void *data, size_t len,
 309                 struct interface *iface, void *dest_addr)
 310 {
 311         struct dhcpv6_client_header *hdr = data;
 312         uint8_t *opts = (uint8_t *)&hdr[1], *opts_end = (uint8_t *)data + len;
 313         bool o_rapid_commit = false;
 314
 315         if (len < sizeof(*hdr))
 316                 return;
 317
 318         syslog(LOG_DEBUG, "Got a DHCPv6-request on %s", iface->name);
 319
 320         /* Construct reply message */
 321         struct __attribute__((packed)) {
 322                 uint8_t msg_type;
 323                 uint8_t tr_id[3];
 324                 uint16_t serverid_type;
 325                 uint16_t serverid_length;
 326                 uint16_t duid_type;
 327                 uint16_t hardware_type;
 328                 uint8_t mac[6];
 329                 uint16_t clientid_type;
 330                 uint16_t clientid_length;
 331                 uint8_t clientid_buf[130];
 332         } dest = {
 333                 .msg_type = DHCPV6_MSG_REPLY,
 334                 .serverid_type = htons(DHCPV6_OPT_SERVERID),
 335                 .serverid_length = htons(10),
 336                 .duid_type = htons(3),
 337                 .hardware_type = htons(1),
 338                 .clientid_type = htons(DHCPV6_OPT_CLIENTID),
 339                 .clientid_buf = {0}
 340         };
 341         odhcpd_get_mac(iface, dest.mac);
 342
 343         struct __attribute__((packed)) {
 344                 uint16_t type;
 345                 uint16_t len;
 346                 uint32_t value;
 347         } maxrt = {htons(DHCPV6_OPT_SOL_MAX_RT), htons(sizeof(maxrt) - 4),
 348                         htonl(60)};
 349
 350         struct __attribute__((packed)) {
 351                 uint16_t type;
 352                 uint16_t len;
 353         } rapid_commit = {htons(DHCPV6_OPT_RAPID_COMMIT), 0};
 354
 355         struct __attribute__((packed)) {
 356                 uint16_t type;
 357                 uint16_t len;
 358                 uint16_t value;
 359         } stat = {htons(DHCPV6_OPT_STATUS), htons(sizeof(stat) - 4),
 360                         htons(DHCPV6_STATUS_USEMULTICAST)};
 361
 362         struct __attribute__((packed)) {
 363                 uint16_t type;
 364                 uint16_t len;
 365                 uint32_t value;
 366         } refresh = {htons(DHCPV6_OPT_INFO_REFRESH), htons(sizeof(uint32_t)),
 367                         htonl(600)};
 368
 369         struct in6_addr dns_addr, *dns_addr_ptr = iface->dns;
 370         size_t dns_cnt = iface->dns_cnt;
 371
 372         if ((dns_cnt == 0) &&
 373                 !odhcpd_get_interface_dns_addr(iface, &dns_addr)) {
 374                 dns_addr_ptr = &dns_addr;
 375                 dns_cnt = 1;
 376         }
 377
 378         struct {
 379                 uint16_t type;
 380                 uint16_t len;
 381         } dns = {htons(DHCPV6_OPT_DNS_SERVERS), htons(dns_cnt * sizeof(*dns_addr_ptr))};
 382
 383         /* SNTP */
 384         struct in6_addr *sntp_addr_ptr = iface->dhcpv6_sntp;
 385         size_t sntp_cnt = 0;
 386
 387         struct {
 388                 uint16_t type;
 389                 uint16_t len;
 390         } dhcpv6_sntp;
 391
 392         /* NTP */
 393         uint8_t *ntp_ptr = iface->dhcpv6_ntp;
 394         uint16_t ntp_len = iface->dhcpv6_ntp_len;
 395         size_t ntp_cnt = 0;
 396
 397         struct {
 398                 uint16_t type;
 399                 uint16_t len;
 400         } ntp;
 401
 402         uint16_t otype, olen;
 403         uint16_t *reqopts = NULL;
 404         uint8_t *odata;
 405         size_t reqopts_len = 0;
 406
 407         dhcpv6_for_each_option(opts, opts_end, otype, olen, odata) {
 408                 if (otype == DHCPV6_OPT_ORO) {
 409                         reqopts_len = olen;
 410                         reqopts = (uint16_t *)odata;
 411                 }
 412         }
 413
 414         for(size_t opt = 0; opt < reqopts_len/2; opt++) {
 415                 if (iface->dhcpv6_sntp_cnt != 0 &&
 416                         DHCPV6_OPT_SNTP_SERVERS == ntohs(reqopts[opt])) {
 417                         sntp_cnt = iface->dhcpv6_sntp_cnt;
 418                         dhcpv6_sntp.type = htons(DHCPV6_OPT_SNTP_SERVERS);
 419                         dhcpv6_sntp.len = htons(sntp_cnt * sizeof(*sntp_addr_ptr));
 420                 } else if (iface->dhcpv6_ntp_cnt != 0 &&
 421                         DHCPV6_OPT_NTP_SERVERS == ntohs(reqopts[opt])) {
 422                         ntp_cnt = iface->dhcpv6_ntp_cnt;
 423                         ntp.type = htons(DHCPV6_OPT_NTP_SERVERS);
 424                         ntp.len = htons(ntp_len);
 425                 }
 426         }
 427
 428         /* DNS Search options */
 429         uint8_t search_buf[256], *search_domain = iface->search;
 430         size_t search_len = iface->search_len;
 431
 432         if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 433                 int len = dn_comp(_res.dnsrch[0], search_buf,
 434                                 sizeof(search_buf), NULL, NULL);
 435                 if (len > 0) {
 436                         search_domain = search_buf;
 437                         search_len = len;
 438                 }
 439         }
 440
 441         struct {
 442                 uint16_t type;
 443                 uint16_t len;
 444         } search = {htons(DHCPV6_OPT_DNS_DOMAIN), htons(search_len)};
 445
 446
 447         struct __attribute__((packed)) dhcpv4o6_server {
 448                 uint16_t type;
 449                 uint16_t len;
 450                 struct in6_addr addr;
 451         } dhcpv4o6_server = {htons(DHCPV6_OPT_4O6_SERVER), htons(sizeof(struct in6_addr)),
 452                         IN6ADDR_ANY_INIT};
 453
 454         struct dhcpv6_cer_id cerid = {
 455 #ifdef EXT_CER_ID
 456                 .type = htons(EXT_CER_ID),
 457 #endif
 458                 .len = htons(36),
 459                 .addr = iface->dhcpv6_pd_cer,
 460         };
 461
 462
 463         uint8_t pdbuf[512];
 464         struct iovec iov[IOV_TOTAL] = {
 465                 [IOV_NESTED] = {NULL, 0},
 466                 [IOV_DEST] = {&dest, (uint8_t*)&dest.clientid_type - (uint8_t*)&dest},
 467                 [IOV_MAXRT] = {&maxrt, sizeof(maxrt)},
 468                 [IOV_RAPID_COMMIT] = {&rapid_commit, 0},
 469                 [IOV_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
 470                 [IOV_DNS_ADDR] = {dns_addr_ptr, dns_cnt * sizeof(*dns_addr_ptr)},
 471                 [IOV_SEARCH] = {&search, (search_len) ? sizeof(search) : 0},
 472                 [IOV_SEARCH_DOMAIN] = {search_domain, search_len},
 473                 [IOV_PDBUF] = {pdbuf, 0},
 474                 [IOV_CERID] = {&cerid, 0},
 475                 [IOV_DHCPV6_RAW] = {iface->dhcpv6_raw, iface->dhcpv6_raw_len},
 476                 [IOV_NTP] = {&ntp, (ntp_cnt) ? sizeof(ntp) : 0},
 477                 [IOV_NTP_ADDR] = {ntp_ptr, (ntp_cnt) ? ntp_len : 0},
 478                 [IOV_SNTP] = {&dhcpv6_sntp, (sntp_cnt) ? sizeof(dhcpv6_sntp) : 0},
 479                 [IOV_SNTP_ADDR] = {sntp_addr_ptr, sntp_cnt * sizeof(*sntp_addr_ptr)},
 480                 [IOV_RELAY_MSG] = {NULL, 0},
 481                 [IOV_DHCPV4O6_SERVER] = {&dhcpv4o6_server, 0},
 482         };
 483
 484         if (hdr->msg_type == DHCPV6_MSG_RELAY_FORW)
 485                 handle_nested_message(data, len, &hdr, &opts, &opts_end, iov);
 486
 487         switch (hdr->msg_type) {
 488         case DHCPV6_MSG_SOLICIT:
 489         case DHCPV6_MSG_REQUEST:
 490         case DHCPV6_MSG_CONFIRM:
 491         case DHCPV6_MSG_RENEW:
 492         case DHCPV6_MSG_REBIND:
 493         case DHCPV6_MSG_RELEASE:
 494         case DHCPV6_MSG_DECLINE:
 495         case DHCPV6_MSG_INFORMATION_REQUEST:
 496         case DHCPV6_MSG_RELAY_FORW:
 497 #ifdef DHCPV4_SUPPORT
 498         case DHCPV6_MSG_DHCPV4_QUERY:
 499 #endif
 500                 break; /* Valid message types for clients */
 501         case DHCPV6_MSG_ADVERTISE:
 502         case DHCPV6_MSG_REPLY:
 503         case DHCPV6_MSG_RECONFIGURE:
 504         case DHCPV6_MSG_RELAY_REPL:
 505         case DHCPV6_MSG_DHCPV4_RESPONSE:
 506 #ifndef DHCPV4_SUPPORT
 507         case DHCPV6_MSG_DHCPV4_QUERY:
 508 #endif
 509         default:
 510                 return; /* Invalid message types for clients */
 511         }
 512
 513         if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 &&
 514             (hdr->msg_type == DHCPV6_MSG_SOLICIT || hdr->msg_type == DHCPV6_MSG_CONFIRM ||
 515              hdr->msg_type == DHCPV6_MSG_REBIND || hdr->msg_type == DHCPV6_MSG_INFORMATION_REQUEST))
 516                 return;
 517
 518         memcpy(dest.tr_id, hdr->transaction_id, sizeof(dest.tr_id));
 519
 520         /* Go through options and find what we need */
 521         dhcpv6_for_each_option(opts, opts_end, otype, olen, odata) {
 522                 if (otype == DHCPV6_OPT_CLIENTID && olen <= 130) {
 523                         dest.clientid_length = htons(olen);
 524                         memcpy(dest.clientid_buf, odata, olen);
 525                         iov[IOV_DEST].iov_len += 4 + olen;
 526                 } else if (otype == DHCPV6_OPT_SERVERID) {
 527                         if (olen != ntohs(dest.serverid_length) ||
 528                                         memcmp(odata, &dest.duid_type, olen))
 529                                 return; /* Not for us */
 530                 } else if (iface->filter_class && otype == DHCPV6_OPT_USER_CLASS) {
 531                         uint8_t *c = odata, *cend = &odata[olen];
 532                         for (; &c[2] <= cend && &c[2 + (c[0] << 8) + c[1]] <= cend; c = &c[2 + (c[0] << 8) + c[1]]) {
 533                                 size_t elen = strlen(iface->filter_class);
 534                                 if (((((size_t)c[0]) << 8) | c[1]) == elen && !memcmp(&c[2], iface->filter_class, elen))
 535                                         return; /* Ignore from homenet */
 536                         }
 537                 } else if (otype == DHCPV6_OPT_IA_PD) {
 538 #ifdef EXT_CER_ID
 539                         iov[IOV_CERID].iov_len = sizeof(cerid);
 540
 541                         if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr)) {
 542                                 struct odhcpd_ipaddr *addrs;
 543                                 ssize_t len = netlink_get_interface_addrs(0, true, &addrs);
 544
 545                                 for (ssize_t i = 0; i < len; ++i)
 546                                         if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr)
 547                                                         || memcmp(&addrs[i].addr, &cerid.addr, sizeof(cerid.addr)) < 0)
 548                                                 cerid.addr = addrs[i].addr.in6;
 549
 550                                 free(addrs);
 551                         }
 552 #endif
 553                 } else if (otype == DHCPV6_OPT_RAPID_COMMIT && hdr->msg_type == DHCPV6_MSG_SOLICIT) {
 554                         iov[IOV_RAPID_COMMIT].iov_len = sizeof(rapid_commit);
 555                         o_rapid_commit = true;
 556                 } else if (otype == DHCPV6_OPT_ORO) {
 557                         for (int i=0; i < olen/2; i++) {
 558                                 uint16_t option = ntohs(((uint16_t *)odata)[i]);
 559
 560                                 switch (option) {
 561 #ifdef DHCPV4_SUPPORT
 562                                 case DHCPV6_OPT_4O6_SERVER:
 563                                         if (iface->dhcpv4) {
 564                                                 /* According to RFC 7341, 7.2. DHCP 4o6 Server Address Option Format:
 565                                                  * This option may also carry no IPv6 addresses, which instructs the
 566                                                  * client to use the All_DHCP_Relay_Agents_and_Servers multicast address
 567                                                  * as the destination address.
 568                                                  *
 569                                                  * The ISC dhclient logs a missing IPv6 address as an error but seems to
 570                                                  * work anyway:
 571                                                  * dhcp4-o-dhcp6-server: expecting at least 16 bytes; got 0
 572                                                  *
 573                                                  * Include the All_DHCP_Relay_Agents_and_Servers multicast address
 574                                                  * to make it explicit which address to use. */
 575                                                 struct dhcpv4o6_server *server = iov[IOV_DHCPV4O6_SERVER].iov_base;
 576
 577                                                 inet_pton(AF_INET6, ALL_DHCPV6_RELAYS, &server->addr);
 578
 579                                                 iov[IOV_DHCPV4O6_SERVER].iov_len = sizeof(dhcpv4o6_server);
 580                                         }
 581                                         break;
 582 #endif /* DHCPV4_SUPPORT */
 583                                 default:
 584                                         break;
 585                                 }
 586                         }
 587                 }
 588         }
 589
 590         if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 &&
 591             (hdr->msg_type == DHCPV6_MSG_REQUEST || hdr->msg_type == DHCPV6_MSG_RENEW ||
 592              hdr->msg_type == DHCPV6_MSG_RELEASE || hdr->msg_type == DHCPV6_MSG_DECLINE)) {
 593                 iov[IOV_STAT].iov_base = &stat;
 594                 iov[IOV_STAT].iov_len = sizeof(stat);
 595
 596                 for (ssize_t i = IOV_STAT + 1; i < IOV_TOTAL; ++i)
 597                         iov[i].iov_len = 0;
 598
 599                 odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface);
 600                 return;
 601         }
 602
 603         if (hdr->msg_type == DHCPV6_MSG_SOLICIT && !o_rapid_commit) {
 604                 dest.msg_type = DHCPV6_MSG_ADVERTISE;
 605         } else if (hdr->msg_type == DHCPV6_MSG_INFORMATION_REQUEST) {
 606                 iov[IOV_REFRESH].iov_base = &refresh;
 607                 iov[IOV_REFRESH].iov_len = sizeof(refresh);
 608
 609                 /* Return inf max rt option in reply to information request */
 610                 maxrt.type = htons(DHCPV6_OPT_INF_MAX_RT);
 611         }
 612
 613 #ifdef DHCPV4_SUPPORT
 614         if (hdr->msg_type == DHCPV6_MSG_DHCPV4_QUERY) {
 615                 struct _packed dhcpv4_msg_data {
 616                         uint16_t type;
 617                         uint16_t len;
 618                         uint8_t msg[1];
 619                 } *msg_opt = (struct dhcpv4_msg_data*)pdbuf;
 620                 ssize_t msglen;
 621
 622                 memset(pdbuf, 0, sizeof(pdbuf));
 623
 624                 msglen = dhcpv6_4o6_query(msg_opt->msg, sizeof(pdbuf) - sizeof(*msg_opt) + 1,
 625                                                 iface, addr, (const void *)hdr, opts_end);
 626                 if (msglen <= 0) {
 627                         syslog(LOG_ERR, "4o6: query failed");
 628                         return;
 629                 }
 630
 631                 msg_opt->type = htons(DHCPV6_OPT_DHCPV4_MSG);
 632                 msg_opt->len = htons(msglen);
 633                 iov[IOV_PDBUF].iov_len = sizeof(*msg_opt) - 1 + msglen;
 634                 dest.msg_type = DHCPV6_MSG_DHCPV4_RESPONSE;
 635         } else
 636 #endif  /* DHCPV4_SUPPORT */
 637         if (hdr->msg_type != DHCPV6_MSG_INFORMATION_REQUEST) {
 638                 ssize_t ialen = dhcpv6_ia_handle_IAs(pdbuf, sizeof(pdbuf), iface, addr, (const void *)hdr, opts_end);
 639
 640                 iov[IOV_PDBUF].iov_len = ialen;
 641                 if (ialen < 0 ||
 642                     (ialen == 0 && (hdr->msg_type == DHCPV6_MSG_REBIND || hdr->msg_type == DHCPV6_MSG_CONFIRM)))
 643                         return;
 644         }
 645
 646         if (iov[IOV_NESTED].iov_len > 0) /* Update length */
 647                 update_nested_message(data, len, iov[IOV_DEST].iov_len + iov[IOV_MAXRT].iov_len +
 648                                       iov[IOV_RAPID_COMMIT].iov_len + iov[IOV_DNS].iov_len +
 649                                       iov[IOV_DNS_ADDR].iov_len + iov[IOV_SEARCH].iov_len +
 650                                       iov[IOV_SEARCH_DOMAIN].iov_len + iov[IOV_PDBUF].iov_len +
 651                                       iov[IOV_DHCPV4O6_SERVER].iov_len +
 652                                       iov[IOV_CERID].iov_len + iov[IOV_DHCPV6_RAW].iov_len +
 653                                       iov[IOV_NTP].iov_len + iov[IOV_NTP_ADDR].iov_len +
 654                                       iov[IOV_SNTP].iov_len + iov[IOV_SNTP_ADDR].iov_len -
 655                                       (4 + opts_end - opts));
 656
 657         syslog(LOG_DEBUG, "Sending a DHCPv6-%s on %s", iov[IOV_NESTED].iov_len ? "relay-reply" : "reply", iface->name);
 658
 659         odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface);
 660 }
 661
 662
 663 /* Central DHCPv6-relay handler */
 664 static void handle_dhcpv6(void *addr, void *data, size_t len,
 665                 struct interface *iface, void *dest_addr)
 666 {
 667         if (iface->dhcpv6 == MODE_SERVER) {
 668                 handle_client_request(addr, data, len, iface, dest_addr);
 669         } else if (iface->dhcpv6 == MODE_RELAY) {
 670                 if (iface->master)
 671                         relay_server_response(data, len);
 672                 else
 673                         relay_client_request(addr, data, len, iface);
 674         }
 675 }
 676
 677
 678 /* Relay server response (regular relay server handling) */
 679 static void relay_server_response(uint8_t *data, size_t len)
 680 {
 681         /* Information we need to gather */
 682         uint8_t *payload_data = NULL;
 683         size_t payload_len = 0;
 684         int32_t ifaceidx = 0;
 685         struct sockaddr_in6 target = {AF_INET6, htons(DHCPV6_CLIENT_PORT),
 686                 0, IN6ADDR_ANY_INIT, 0};
 687         int otype, olen;
 688         uint8_t *odata, *end = data + len;
 689         /* Relay DHCPv6 reply from server to client */
 690         struct dhcpv6_relay_header *h = (void*)data;
 691
 692         syslog(LOG_DEBUG, "Got a DHCPv6-relay-reply");
 693
 694         if (len < sizeof(*h) || h->msg_type != DHCPV6_MSG_RELAY_REPL)
 695                 return;
 696
 697         memcpy(&target.sin6_addr, &h->peer_address, sizeof(struct in6_addr));
 698
 699         /* Go through options and find what we need */
 700         dhcpv6_for_each_option(h->options, end, otype, olen, odata) {
 701                 if (otype == DHCPV6_OPT_INTERFACE_ID
 702                                 && olen == sizeof(ifaceidx)) {
 703                         memcpy(&ifaceidx, odata, sizeof(ifaceidx));
 704                 } else if (otype == DHCPV6_OPT_RELAY_MSG) {
 705                         payload_data = odata;
 706                         payload_len = olen;
 707                 }
 708         }
 709
 710         /* Invalid interface-id or basic payload */
 711         struct interface *iface = odhcpd_get_interface_by_index(ifaceidx);
 712         if (!iface || iface->master || !payload_data || payload_len < 4)
 713                 return;
 714
 715         bool is_authenticated = false;
 716         struct in6_addr *dns_ptr = NULL;
 717         size_t dns_count = 0;
 718
 719         /* If the payload is relay-reply we have to send to the server port */
 720         if (payload_data[0] == DHCPV6_MSG_RELAY_REPL) {
 721                 target.sin6_port = htons(DHCPV6_SERVER_PORT);
 722         } else { /* Go through the payload data */
 723                 struct dhcpv6_client_header *h = (void*)payload_data;
 724                 end = payload_data + payload_len;
 725
 726                 dhcpv6_for_each_option(&h[1], end, otype, olen, odata) {
 727                         if (otype == DHCPV6_OPT_DNS_SERVERS && olen >= 16) {
 728                                 dns_ptr = (struct in6_addr*)odata;
 729                                 dns_count = olen / 16;
 730                         } else if (otype == DHCPV6_OPT_AUTH) {
 731                                 is_authenticated = true;
 732                         }
 733                 }
 734         }
 735
 736         /* Rewrite DNS servers if requested */
 737         if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
 738                 if (is_authenticated)
 739                         return; /* Impossible to rewrite */
 740
 741                 const struct in6_addr *rewrite = iface->dns;
 742                 struct in6_addr addr;
 743                 size_t rewrite_cnt = iface->dns_cnt;
 744
 745                 if (rewrite_cnt == 0) {
 746                         if (odhcpd_get_interface_dns_addr(iface, &addr))
 747                                 return; /* Unable to get interface address */
 748
 749                         rewrite = &addr;
 750                         rewrite_cnt = 1;
 751                 }
 752
 753                 /* Copy over any other addresses */
 754                 for (size_t i = 0; i < dns_count; ++i) {
 755                         size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 756                         memcpy(&dns_ptr[i], &rewrite[j], sizeof(*rewrite));
 757                 }
 758         }
 759
 760         struct iovec iov = {payload_data, payload_len};
 761
 762         syslog(LOG_DEBUG, "Sending a DHCPv6-reply on %s", iface->name);
 763
 764         odhcpd_send(iface->dhcpv6_event.uloop.fd, &target, &iov, 1, iface);
 765 }
 766
 767 static struct odhcpd_ipaddr *relay_link_address(struct interface *iface)
 768 {
 769         struct odhcpd_ipaddr *addr = NULL;
 770         time_t now = odhcpd_time();
 771
 772         for (size_t i = 0; i < iface->addr6_len; i++) {
 773                 if (iface->addr6[i].valid <= (uint32_t)now)
 774                         continue;
 775
 776                 if (iface->addr6[i].preferred > (uint32_t)now) {
 777                         addr = &iface->addr6[i];
 778                         break;
 779                 }
 780
 781                 if (!addr || (iface->addr6[i].valid > addr->valid))
 782                         addr = &iface->addr6[i];
 783         }
 784
 785         return addr;
 786 }
 787
 788 /* Relay client request (regular DHCPv6-relay) */
 789 static void relay_client_request(struct sockaddr_in6 *source,
 790                 const void *data, size_t len, struct interface *iface)
 791 {
 792         const struct dhcpv6_relay_header *h = data;
 793         /* Construct our forwarding envelope */
 794         struct dhcpv6_relay_forward_envelope hdr = {
 795                 .msg_type = DHCPV6_MSG_RELAY_FORW,
 796                 .hop_count = 0,
 797                 .interface_id_type = htons(DHCPV6_OPT_INTERFACE_ID),
 798                 .interface_id_len = htons(sizeof(uint32_t)),
 799                 .relay_message_type = htons(DHCPV6_OPT_RELAY_MSG),
 800                 .relay_message_len = htons(len),
 801         };
 802         struct iovec iov[2] = {{&hdr, sizeof(hdr)}, {(void *)data, len}};
 803         struct interface *c;
 804         struct odhcpd_ipaddr *ip;
 805         struct sockaddr_in6 s;
 806
 807         if (h->msg_type == DHCPV6_MSG_RELAY_REPL ||
 808             h->msg_type == DHCPV6_MSG_RECONFIGURE ||
 809             h->msg_type == DHCPV6_MSG_REPLY ||
 810             h->msg_type == DHCPV6_MSG_ADVERTISE)
 811                 return; /* Invalid message types for client */
 812
 813         syslog(LOG_DEBUG, "Got a DHCPv6-request on %s", iface->name);
 814
 815         if (h->msg_type == DHCPV6_MSG_RELAY_FORW) { /* handle relay-forward */
 816                 if (h->hop_count >= DHCPV6_HOP_COUNT_LIMIT)
 817                         return; /* Invalid hop count */
 818
 819                 hdr.hop_count = h->hop_count + 1;
 820         }
 821
 822         /* use memcpy here as the destination fields are unaligned */
 823         memcpy(&hdr.peer_address, &source->sin6_addr, sizeof(struct in6_addr));
 824         memcpy(&hdr.interface_id_data, &iface->ifindex, sizeof(iface->ifindex));
 825
 826         /* Detect public IP of slave interface to use as link-address */
 827         ip = relay_link_address(iface);
 828         if (ip)
 829                 memcpy(&hdr.link_address, &ip->addr.in6, sizeof(hdr.link_address));
 830
 831         memset(&s, 0, sizeof(s));
 832         s.sin6_family = AF_INET6;
 833         s.sin6_port = htons(DHCPV6_SERVER_PORT);
 834         inet_pton(AF_INET6, ALL_DHCPV6_SERVERS, &s.sin6_addr);
 835
 836         avl_for_each_element(&interfaces, c, avl) {
 837                 if (!c->master || c->dhcpv6 != MODE_RELAY)
 838                         continue;
 839
 840                 if (!ip) {
 841                         /* No suitable address! Is the slave not configured yet?
 842                          * Detect public IP of master interface and use it instead
 843                          * This is WRONG and probably violates the RFC. However
 844                          * otherwise we have a hen and egg problem because the
 845                          * slave-interface cannot be auto-configured. */
 846                         ip = relay_link_address(c);
 847                         if (!ip)
 848                                 continue; /* Could not obtain a suitable address */
 849
 850                         memcpy(&hdr.link_address, &ip->addr.in6, sizeof(hdr.link_address));
 851                         ip = NULL;
 852                 }
 853
 854                 syslog(LOG_DEBUG, "Sending a DHCPv6-relay-forward on %s", c->name);
 855
 856                 odhcpd_send(c->dhcpv6_event.uloop.fd, &s, iov, 2, c);
 857         }
 858 }