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_RELAY_MSG,
 180         IOV_DHCPV4O6_SERVER,
 181         IOV_TOTAL
 182 };
 183
 184 static void handle_nested_message(uint8_t *data, size_t len,
 185                                   struct dhcpv6_client_header **c_hdr, uint8_t **opts,
 186                                   uint8_t **end, struct iovec iov[IOV_TOTAL])
 187 {
 188         struct dhcpv6_relay_header *r_hdr = (struct dhcpv6_relay_header *)data;
 189         uint16_t otype, olen;
 190         uint8_t *odata;
 191
 192         if (iov[IOV_NESTED].iov_base == NULL) {
 193                 iov[IOV_NESTED].iov_base = data;
 194                 iov[IOV_NESTED].iov_len = len;
 195         }
 196
 197         if (len < sizeof(struct dhcpv6_client_header))
 198                 return;
 199
 200         if (r_hdr->msg_type != DHCPV6_MSG_RELAY_FORW) {
 201                 iov[IOV_NESTED].iov_len = data - (uint8_t *)iov[IOV_NESTED].iov_base;
 202                 *c_hdr = (void *)data;
 203                 *opts = (uint8_t *)&(*c_hdr)[1];
 204                 *end = data + len;
 205                 return;
 206         }
 207
 208         dhcpv6_for_each_option(r_hdr->options, data + len, otype, olen, odata) {
 209                 if (otype == DHCPV6_OPT_RELAY_MSG) {
 210                         iov[IOV_RELAY_MSG].iov_base = odata + olen;
 211                         iov[IOV_RELAY_MSG].iov_len = (((uint8_t *)iov[IOV_NESTED].iov_base) +
 212                                         iov[IOV_NESTED].iov_len) - (odata + olen);
 213                         handle_nested_message(odata, olen, c_hdr, opts, end, iov);
 214                         return;
 215                 }
 216         }
 217 }
 218
 219
 220 static void update_nested_message(uint8_t *data, size_t len, ssize_t pdiff)
 221 {
 222         struct dhcpv6_relay_header *hdr = (struct dhcpv6_relay_header*)data;
 223         if (hdr->msg_type != DHCPV6_MSG_RELAY_FORW)
 224                 return;
 225
 226         hdr->msg_type = DHCPV6_MSG_RELAY_REPL;
 227
 228         uint16_t otype, olen;
 229         uint8_t *odata;
 230         dhcpv6_for_each_option(hdr->options, data + len, otype, olen, odata) {
 231                 if (otype == DHCPV6_OPT_RELAY_MSG) {
 232                         olen += pdiff;
 233                         odata[-2] = (olen >> 8) & 0xff;
 234                         odata[-1] = olen & 0xff;
 235                         update_nested_message(odata, olen - pdiff, pdiff);
 236                         return;
 237                 }
 238         }
 239 }
 240
 241 #ifdef DHCPV4_SUPPORT
 242
 243 struct dhcpv4_msg_data {
 244         uint8_t *msg;
 245         size_t maxsize;
 246         ssize_t len;
 247 };
 248
 249 static int send_reply(_unused const void *buf, size_t len,
 250                       _unused const struct sockaddr *dest, _unused socklen_t dest_len,
 251                       _unused void *opaque)
 252 {
 253         struct dhcpv4_msg_data *reply = opaque;
 254
 255         if (len > reply->maxsize) {
 256                 syslog(LOG_ERR, "4o6: reply too large, %u > %u", len, reply->maxsize);
 257                 reply->len = -1;
 258         } else {
 259                 memcpy(reply->msg, buf, len);
 260                 reply->len = len;
 261         }
 262
 263         return reply->len;
 264 }
 265
 266 static ssize_t dhcpv6_4o6_query(uint8_t *buf, size_t buflen,
 267                                 struct interface *iface,
 268                                 const struct sockaddr_in6 *addr,
 269                                 const void *data, const uint8_t *end)
 270 {
 271         const struct dhcpv6_client_header *hdr = data;
 272         uint16_t otype, olen, msgv4_len = 0;
 273         uint8_t *msgv4_data = NULL;
 274         uint8_t *start = (uint8_t *)&hdr[1], *odata;
 275         struct sockaddr_in addrv4;
 276         struct dhcpv4_msg_data reply = { .msg = buf, .maxsize = buflen, .len = -1 };
 277
 278         dhcpv6_for_each_option(start, end, otype, olen, odata) {
 279                 if (otype == DHCPV6_OPT_DHCPV4_MSG) {
 280                         msgv4_data = odata;
 281                         msgv4_len = olen;
 282                 }
 283         }
 284
 285         if (!msgv4_data || msgv4_len == 0) {
 286                 syslog(LOG_ERR, "4o6: missing DHCPv4 message option (%d)", DHCPV6_OPT_DHCPV4_MSG);
 287                 return -1;
 288         }
 289
 290         // Dummy IPv4 address
 291         memset(&addrv4, 0, sizeof(addrv4));
 292         addrv4.sin_family = AF_INET;
 293         addrv4.sin_addr.s_addr = INADDR_ANY;
 294         addrv4.sin_port = htons(DHCPV4_CLIENT_PORT);
 295
 296         dhcpv4_handle_msg(&addrv4, msgv4_data, msgv4_len,
 297                           iface, NULL, send_reply, &reply);
 298
 299         return reply.len;
 300 }
 301 #endif  /* DHCPV4_SUPPORT */
 302
 303 /* Simple DHCPv6-server for information requests */
 304 static void handle_client_request(void *addr, void *data, size_t len,
 305                 struct interface *iface, void *dest_addr)
 306 {
 307         struct dhcpv6_client_header *hdr = data;
 308         uint8_t *opts = (uint8_t *)&hdr[1], *opts_end = (uint8_t *)data + len;
 309         bool o_rapid_commit = false;
 310
 311         if (len < sizeof(*hdr))
 312                 return;
 313
 314         syslog(LOG_DEBUG, "Got a DHCPv6-request on %s", iface->name);
 315
 316         /* Construct reply message */
 317         struct __attribute__((packed)) {
 318                 uint8_t msg_type;
 319                 uint8_t tr_id[3];
 320                 uint16_t serverid_type;
 321                 uint16_t serverid_length;
 322                 uint16_t duid_type;
 323                 uint16_t hardware_type;
 324                 uint8_t mac[6];
 325                 uint16_t clientid_type;
 326                 uint16_t clientid_length;
 327                 uint8_t clientid_buf[130];
 328         } dest = {
 329                 .msg_type = DHCPV6_MSG_REPLY,
 330                 .serverid_type = htons(DHCPV6_OPT_SERVERID),
 331                 .serverid_length = htons(10),
 332                 .duid_type = htons(3),
 333                 .hardware_type = htons(1),
 334                 .clientid_type = htons(DHCPV6_OPT_CLIENTID),
 335                 .clientid_buf = {0}
 336         };
 337         odhcpd_get_mac(iface, dest.mac);
 338
 339         struct __attribute__((packed)) {
 340                 uint16_t type;
 341                 uint16_t len;
 342                 uint32_t value;
 343         } maxrt = {htons(DHCPV6_OPT_SOL_MAX_RT), htons(sizeof(maxrt) - 4),
 344                         htonl(60)};
 345
 346         struct __attribute__((packed)) {
 347                 uint16_t type;
 348                 uint16_t len;
 349         } rapid_commit = {htons(DHCPV6_OPT_RAPID_COMMIT), 0};
 350
 351         struct __attribute__((packed)) {
 352                 uint16_t type;
 353                 uint16_t len;
 354                 uint16_t value;
 355         } stat = {htons(DHCPV6_OPT_STATUS), htons(sizeof(stat) - 4),
 356                         htons(DHCPV6_STATUS_USEMULTICAST)};
 357
 358         struct __attribute__((packed)) {
 359                 uint16_t type;
 360                 uint16_t len;
 361                 uint32_t value;
 362         } refresh = {htons(DHCPV6_OPT_INFO_REFRESH), htons(sizeof(uint32_t)),
 363                         htonl(600)};
 364
 365         struct in6_addr dns_addr, *dns_addr_ptr = iface->dns;
 366         size_t dns_cnt = iface->dns_cnt;
 367
 368         if ((dns_cnt == 0) &&
 369                 !odhcpd_get_interface_dns_addr(iface, &dns_addr)) {
 370                 dns_addr_ptr = &dns_addr;
 371                 dns_cnt = 1;
 372         }
 373
 374         struct {
 375                 uint16_t type;
 376                 uint16_t len;
 377         } dns = {htons(DHCPV6_OPT_DNS_SERVERS), htons(dns_cnt * sizeof(*dns_addr_ptr))};
 378
 379
 380
 381         /* DNS Search options */
 382         uint8_t search_buf[256], *search_domain = iface->search;
 383         size_t search_len = iface->search_len;
 384
 385         if (!search_domain && !res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 386                 int len = dn_comp(_res.dnsrch[0], search_buf,
 387                                 sizeof(search_buf), NULL, NULL);
 388                 if (len > 0) {
 389                         search_domain = search_buf;
 390                         search_len = len;
 391                 }
 392         }
 393
 394         struct {
 395                 uint16_t type;
 396                 uint16_t len;
 397         } search = {htons(DHCPV6_OPT_DNS_DOMAIN), htons(search_len)};
 398
 399
 400         struct __attribute__((packed)) {
 401                 uint16_t type;
 402                 uint16_t len;
 403         } dhcpv4o6_server = {htons(DHCPV6_OPT_4O6_SERVER), 0};
 404
 405         struct dhcpv6_cer_id cerid = {
 406 #ifdef EXT_CER_ID
 407                 .type = htons(EXT_CER_ID),
 408 #endif
 409                 .len = htons(36),
 410                 .addr = iface->dhcpv6_pd_cer,
 411         };
 412
 413
 414         uint8_t pdbuf[512];
 415         struct iovec iov[IOV_TOTAL] = {
 416                 [IOV_NESTED] = {NULL, 0},
 417                 [IOV_DEST] = {&dest, (uint8_t*)&dest.clientid_type - (uint8_t*)&dest},
 418                 [IOV_MAXRT] = {&maxrt, sizeof(maxrt)},
 419                 [IOV_RAPID_COMMIT] = {&rapid_commit, 0},
 420                 [IOV_DNS] = {&dns, (dns_cnt) ? sizeof(dns) : 0},
 421                 [IOV_DNS_ADDR] = {dns_addr_ptr, dns_cnt * sizeof(*dns_addr_ptr)},
 422                 [IOV_SEARCH] = {&search, (search_len) ? sizeof(search) : 0},
 423                 [IOV_SEARCH_DOMAIN] = {search_domain, search_len},
 424                 [IOV_PDBUF] = {pdbuf, 0},
 425                 [IOV_CERID] = {&cerid, 0},
 426                 [IOV_DHCPV6_RAW] = {iface->dhcpv6_raw, iface->dhcpv6_raw_len},
 427                 [IOV_RELAY_MSG] = {NULL, 0},
 428                 [IOV_DHCPV4O6_SERVER] = {&dhcpv4o6_server, 0},
 429         };
 430
 431         if (hdr->msg_type == DHCPV6_MSG_RELAY_FORW)
 432                 handle_nested_message(data, len, &hdr, &opts, &opts_end, iov);
 433
 434         switch (hdr->msg_type) {
 435         case DHCPV6_MSG_SOLICIT:
 436         case DHCPV6_MSG_REQUEST:
 437         case DHCPV6_MSG_CONFIRM:
 438         case DHCPV6_MSG_RENEW:
 439         case DHCPV6_MSG_REBIND:
 440         case DHCPV6_MSG_RELEASE:
 441         case DHCPV6_MSG_DECLINE:
 442         case DHCPV6_MSG_INFORMATION_REQUEST:
 443         case DHCPV6_MSG_RELAY_FORW:
 444 #ifdef DHCPV4_SUPPORT
 445         case DHCPV6_MSG_DHCPV4_QUERY:
 446 #endif
 447                 break; /* Valid message types for clients */
 448         case DHCPV6_MSG_ADVERTISE:
 449         case DHCPV6_MSG_REPLY:
 450         case DHCPV6_MSG_RECONFIGURE:
 451         case DHCPV6_MSG_RELAY_REPL:
 452         case DHCPV6_MSG_DHCPV4_RESPONSE:
 453 #ifndef DHCPV4_SUPPORT
 454         case DHCPV6_MSG_DHCPV4_QUERY:
 455 #endif
 456         default:
 457                 return; /* Invalid message types for clients */
 458         }
 459
 460         if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 &&
 461             (hdr->msg_type == DHCPV6_MSG_SOLICIT || hdr->msg_type == DHCPV6_MSG_CONFIRM ||
 462              hdr->msg_type == DHCPV6_MSG_REBIND || hdr->msg_type == DHCPV6_MSG_INFORMATION_REQUEST))
 463                 return;
 464
 465         memcpy(dest.tr_id, hdr->transaction_id, sizeof(dest.tr_id));
 466
 467         /* Go through options and find what we need */
 468         uint16_t otype, olen;
 469         uint8_t *odata;
 470         dhcpv6_for_each_option(opts, opts_end, otype, olen, odata) {
 471                 if (otype == DHCPV6_OPT_CLIENTID && olen <= 130) {
 472                         dest.clientid_length = htons(olen);
 473                         memcpy(dest.clientid_buf, odata, olen);
 474                         iov[IOV_DEST].iov_len += 4 + olen;
 475                 } else if (otype == DHCPV6_OPT_SERVERID) {
 476                         if (olen != ntohs(dest.serverid_length) ||
 477                                         memcmp(odata, &dest.duid_type, olen))
 478                                 return; /* Not for us */
 479                 } else if (iface->filter_class && otype == DHCPV6_OPT_USER_CLASS) {
 480                         uint8_t *c = odata, *cend = &odata[olen];
 481                         for (; &c[2] <= cend && &c[2 + (c[0] << 8) + c[1]] <= cend; c = &c[2 + (c[0] << 8) + c[1]]) {
 482                                 size_t elen = strlen(iface->filter_class);
 483                                 if (((((size_t)c[0]) << 8) | c[1]) == elen && !memcmp(&c[2], iface->filter_class, elen))
 484                                         return; /* Ignore from homenet */
 485                         }
 486                 } else if (otype == DHCPV6_OPT_IA_PD) {
 487 #ifdef EXT_CER_ID
 488                         iov[IOV_CERID].iov_len = sizeof(cerid);
 489
 490                         if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr)) {
 491                                 struct odhcpd_ipaddr *addrs;
 492                                 ssize_t len = netlink_get_interface_addrs(0, true, &addrs);
 493
 494                                 for (ssize_t i = 0; i < len; ++i)
 495                                         if (IN6_IS_ADDR_UNSPECIFIED(&cerid.addr)
 496                                                         || memcmp(&addrs[i].addr, &cerid.addr, sizeof(cerid.addr)) < 0)
 497                                                 cerid.addr = addrs[i].addr.in6;
 498
 499                                 free(addrs);
 500                         }
 501 #endif
 502                 } else if (otype == DHCPV6_OPT_RAPID_COMMIT && hdr->msg_type == DHCPV6_MSG_SOLICIT) {
 503                         iov[IOV_RAPID_COMMIT].iov_len = sizeof(rapid_commit);
 504                         o_rapid_commit = true;
 505                 } else if (otype == DHCPV6_OPT_ORO) {
 506                         for (int i=0; i < olen/2; i++) {
 507                                 uint16_t option = ntohs(((uint16_t *)odata)[i]);
 508                                 switch (option) {
 509 #ifdef DHCPV4_SUPPORT
 510                                 case DHCPV6_OPT_4O6_SERVER:
 511                                         if (iface->dhcpv4)
 512                                                 iov[IOV_DHCPV4O6_SERVER].iov_len = sizeof(dhcpv4o6_server);
 513                                         break;
 514 #endif /* DHCPV4_SUPPORT */
 515                                 default:
 516                                         break;
 517                                 }
 518                         }
 519                 }
 520         }
 521
 522         if (!IN6_IS_ADDR_MULTICAST((struct in6_addr *)dest_addr) && iov[IOV_NESTED].iov_len == 0 &&
 523             (hdr->msg_type == DHCPV6_MSG_REQUEST || hdr->msg_type == DHCPV6_MSG_RENEW ||
 524              hdr->msg_type == DHCPV6_MSG_RELEASE || hdr->msg_type == DHCPV6_MSG_DECLINE)) {
 525                 iov[IOV_STAT].iov_base = &stat;
 526                 iov[IOV_STAT].iov_len = sizeof(stat);
 527
 528                 for (ssize_t i = IOV_STAT + 1; i < IOV_TOTAL; ++i)
 529                         iov[i].iov_len = 0;
 530
 531                 odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface);
 532                 return;
 533         }
 534
 535         if (hdr->msg_type == DHCPV6_MSG_SOLICIT && !o_rapid_commit) {
 536                 dest.msg_type = DHCPV6_MSG_ADVERTISE;
 537         } else if (hdr->msg_type == DHCPV6_MSG_INFORMATION_REQUEST) {
 538                 iov[IOV_REFRESH].iov_base = &refresh;
 539                 iov[IOV_REFRESH].iov_len = sizeof(refresh);
 540
 541                 /* Return inf max rt option in reply to information request */
 542                 maxrt.type = htons(DHCPV6_OPT_INF_MAX_RT);
 543         }
 544
 545 #ifdef DHCPV4_SUPPORT
 546         if (hdr->msg_type == DHCPV6_MSG_DHCPV4_QUERY) {
 547                 struct _packed dhcpv4_msg_data {
 548                         uint16_t type;
 549                         uint16_t len;
 550                         uint8_t msg[1];
 551                 } *msg_opt = (struct dhcpv4_msg_data*)pdbuf;
 552                 ssize_t msglen;
 553
 554                 memset(pdbuf, 0, sizeof(pdbuf));
 555
 556                 msglen = dhcpv6_4o6_query(msg_opt->msg, sizeof(pdbuf) - sizeof(*msg_opt) + 1,
 557                                                 iface, addr, (const void *)hdr, opts_end);
 558                 if (msglen <= 0) {
 559                         syslog(LOG_ERR, "4o6: query failed");
 560                         return;
 561                 }
 562
 563                 msg_opt->type = htons(DHCPV6_OPT_DHCPV4_MSG);
 564                 msg_opt->len = htons(msglen);
 565                 iov[IOV_PDBUF].iov_len = sizeof(*msg_opt) - 1 + msglen;
 566                 dest.msg_type = DHCPV6_MSG_DHCPV4_RESPONSE;
 567         } else
 568 #endif  /* DHCPV4_SUPPORT */
 569         if (hdr->msg_type != DHCPV6_MSG_INFORMATION_REQUEST) {
 570                 ssize_t ialen = dhcpv6_ia_handle_IAs(pdbuf, sizeof(pdbuf), iface, addr, (const void *)hdr, opts_end);
 571
 572                 iov[IOV_PDBUF].iov_len = ialen;
 573                 if (ialen < 0 ||
 574                     (ialen == 0 && (hdr->msg_type == DHCPV6_MSG_REBIND || hdr->msg_type == DHCPV6_MSG_CONFIRM)))
 575                         return;
 576         }
 577
 578         if (iov[IOV_NESTED].iov_len > 0) /* Update length */
 579                 update_nested_message(data, len, iov[IOV_DEST].iov_len + iov[IOV_MAXRT].iov_len +
 580                                       iov[IOV_RAPID_COMMIT].iov_len + iov[IOV_DNS].iov_len +
 581                                       iov[IOV_DNS_ADDR].iov_len + iov[IOV_SEARCH].iov_len +
 582                                       iov[IOV_SEARCH_DOMAIN].iov_len + iov[IOV_PDBUF].iov_len +
 583                                       iov[IOV_DHCPV4O6_SERVER].iov_len +
 584                                       iov[IOV_CERID].iov_len + iov[IOV_DHCPV6_RAW].iov_len -
 585                                       (4 + opts_end - opts));
 586
 587         syslog(LOG_DEBUG, "Sending a DHCPv6-%s on %s", iov[IOV_NESTED].iov_len ? "relay-reply" : "reply", iface->name);
 588
 589         odhcpd_send(iface->dhcpv6_event.uloop.fd, addr, iov, ARRAY_SIZE(iov), iface);
 590 }
 591
 592
 593 /* Central DHCPv6-relay handler */
 594 static void handle_dhcpv6(void *addr, void *data, size_t len,
 595                 struct interface *iface, void *dest_addr)
 596 {
 597         if (iface->dhcpv6 == MODE_SERVER) {
 598                 handle_client_request(addr, data, len, iface, dest_addr);
 599         } else if (iface->dhcpv6 == MODE_RELAY) {
 600                 if (iface->master)
 601                         relay_server_response(data, len);
 602                 else
 603                         relay_client_request(addr, data, len, iface);
 604         }
 605 }
 606
 607
 608 /* Relay server response (regular relay server handling) */
 609 static void relay_server_response(uint8_t *data, size_t len)
 610 {
 611         /* Information we need to gather */
 612         uint8_t *payload_data = NULL;
 613         size_t payload_len = 0;
 614         int32_t ifaceidx = 0;
 615         struct sockaddr_in6 target = {AF_INET6, htons(DHCPV6_CLIENT_PORT),
 616                 0, IN6ADDR_ANY_INIT, 0};
 617         int otype, olen;
 618         uint8_t *odata, *end = data + len;
 619         /* Relay DHCPv6 reply from server to client */
 620         struct dhcpv6_relay_header *h = (void*)data;
 621
 622         syslog(LOG_DEBUG, "Got a DHCPv6-relay-reply");
 623
 624         if (len < sizeof(*h) || h->msg_type != DHCPV6_MSG_RELAY_REPL)
 625                 return;
 626
 627         memcpy(&target.sin6_addr, &h->peer_address, sizeof(struct in6_addr));
 628
 629         /* Go through options and find what we need */
 630         dhcpv6_for_each_option(h->options, end, otype, olen, odata) {
 631                 if (otype == DHCPV6_OPT_INTERFACE_ID
 632                                 && olen == sizeof(ifaceidx)) {
 633                         memcpy(&ifaceidx, odata, sizeof(ifaceidx));
 634                 } else if (otype == DHCPV6_OPT_RELAY_MSG) {
 635                         payload_data = odata;
 636                         payload_len = olen;
 637                 }
 638         }
 639
 640         /* Invalid interface-id or basic payload */
 641         struct interface *iface = odhcpd_get_interface_by_index(ifaceidx);
 642         if (!iface || iface->master || !payload_data || payload_len < 4)
 643                 return;
 644
 645         bool is_authenticated = false;
 646         struct in6_addr *dns_ptr = NULL;
 647         size_t dns_count = 0;
 648
 649         /* If the payload is relay-reply we have to send to the server port */
 650         if (payload_data[0] == DHCPV6_MSG_RELAY_REPL) {
 651                 target.sin6_port = htons(DHCPV6_SERVER_PORT);
 652         } else { /* Go through the payload data */
 653                 struct dhcpv6_client_header *h = (void*)payload_data;
 654                 end = payload_data + payload_len;
 655
 656                 dhcpv6_for_each_option(&h[1], end, otype, olen, odata) {
 657                         if (otype == DHCPV6_OPT_DNS_SERVERS && olen >= 16) {
 658                                 dns_ptr = (struct in6_addr*)odata;
 659                                 dns_count = olen / 16;
 660                         } else if (otype == DHCPV6_OPT_AUTH) {
 661                                 is_authenticated = true;
 662                         }
 663                 }
 664         }
 665
 666         /* Rewrite DNS servers if requested */
 667         if (iface->always_rewrite_dns && dns_ptr && dns_count > 0) {
 668                 if (is_authenticated)
 669                         return; /* Impossible to rewrite */
 670
 671                 const struct in6_addr *rewrite = iface->dns;
 672                 struct in6_addr addr;
 673                 size_t rewrite_cnt = iface->dns_cnt;
 674
 675                 if (rewrite_cnt == 0) {
 676                         if (odhcpd_get_interface_dns_addr(iface, &addr))
 677                                 return; /* Unable to get interface address */
 678
 679                         rewrite = &addr;
 680                         rewrite_cnt = 1;
 681                 }
 682
 683                 /* Copy over any other addresses */
 684                 for (size_t i = 0; i < dns_count; ++i) {
 685                         size_t j = (i < rewrite_cnt) ? i : rewrite_cnt - 1;
 686                         memcpy(&dns_ptr[i], &rewrite[j], sizeof(*rewrite));
 687                 }
 688         }
 689
 690         struct iovec iov = {payload_data, payload_len};
 691
 692         syslog(LOG_DEBUG, "Sending a DHCPv6-reply on %s", iface->name);
 693
 694         odhcpd_send(iface->dhcpv6_event.uloop.fd, &target, &iov, 1, iface);
 695 }
 696
 697 static struct odhcpd_ipaddr *relay_link_address(struct interface *iface)
 698 {
 699         struct odhcpd_ipaddr *addr = NULL;
 700         time_t now = odhcpd_time();
 701
 702         for (size_t i = 0; i < iface->addr6_len; i++) {
 703                 if (iface->addr6[i].valid <= (uint32_t)now)
 704                         continue;
 705
 706                 if (iface->addr6[i].preferred > (uint32_t)now) {
 707                         addr = &iface->addr6[i];
 708                         break;
 709                 }
 710
 711                 if (!addr || (iface->addr6[i].valid > addr->valid))
 712                         addr = &iface->addr6[i];
 713         }
 714
 715         return addr;
 716 }
 717
 718 /* Relay client request (regular DHCPv6-relay) */
 719 static void relay_client_request(struct sockaddr_in6 *source,
 720                 const void *data, size_t len, struct interface *iface)
 721 {
 722         const struct dhcpv6_relay_header *h = data;
 723         /* Construct our forwarding envelope */
 724         struct dhcpv6_relay_forward_envelope hdr = {
 725                 .msg_type = DHCPV6_MSG_RELAY_FORW,
 726                 .hop_count = 0,
 727                 .interface_id_type = htons(DHCPV6_OPT_INTERFACE_ID),
 728                 .interface_id_len = htons(sizeof(uint32_t)),
 729                 .relay_message_type = htons(DHCPV6_OPT_RELAY_MSG),
 730                 .relay_message_len = htons(len),
 731         };
 732         struct iovec iov[2] = {{&hdr, sizeof(hdr)}, {(void *)data, len}};
 733         struct interface *c;
 734         struct odhcpd_ipaddr *ip;
 735         struct sockaddr_in6 s;
 736
 737         if (h->msg_type == DHCPV6_MSG_RELAY_REPL ||
 738             h->msg_type == DHCPV6_MSG_RECONFIGURE ||
 739             h->msg_type == DHCPV6_MSG_REPLY ||
 740             h->msg_type == DHCPV6_MSG_ADVERTISE)
 741                 return; /* Invalid message types for client */
 742
 743         syslog(LOG_DEBUG, "Got a DHCPv6-request on %s", iface->name);
 744
 745         if (h->msg_type == DHCPV6_MSG_RELAY_FORW) { /* handle relay-forward */
 746                 if (h->hop_count >= DHCPV6_HOP_COUNT_LIMIT)
 747                         return; /* Invalid hop count */
 748
 749                 hdr.hop_count = h->hop_count + 1;
 750         }
 751
 752         /* use memcpy here as the destination fields are unaligned */
 753         memcpy(&hdr.peer_address, &source->sin6_addr, sizeof(struct in6_addr));
 754         memcpy(&hdr.interface_id_data, &iface->ifindex, sizeof(iface->ifindex));
 755
 756         /* Detect public IP of slave interface to use as link-address */
 757         ip = relay_link_address(iface);
 758         if (ip)
 759                 memcpy(&hdr.link_address, &ip->addr.in6, sizeof(hdr.link_address));
 760
 761         memset(&s, 0, sizeof(s));
 762         s.sin6_family = AF_INET6;
 763         s.sin6_port = htons(DHCPV6_SERVER_PORT);
 764         inet_pton(AF_INET6, ALL_DHCPV6_SERVERS, &s.sin6_addr);
 765
 766         avl_for_each_element(&interfaces, c, avl) {
 767                 if (!c->master || c->dhcpv6 != MODE_RELAY)
 768                         continue;
 769
 770                 if (!ip) {
 771                         /* No suitable address! Is the slave not configured yet?
 772                          * Detect public IP of master interface and use it instead
 773                          * This is WRONG and probably violates the RFC. However
 774                          * otherwise we have a hen and egg problem because the
 775                          * slave-interface cannot be auto-configured. */
 776                         ip = relay_link_address(c);
 777                         if (!ip)
 778                                 continue; /* Could not obtain a suitable address */
 779
 780                         memcpy(&hdr.link_address, &ip->addr.in6, sizeof(hdr.link_address));
 781                         ip = NULL;
 782                 }
 783
 784                 syslog(LOG_DEBUG, "Sending a DHCPv6-relay-forward on %s", c->name);
 785
 786                 odhcpd_send(c->dhcpv6_event.uloop.fd, &s, iov, 2, c);
 787         }
 788 }