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 #include <time.h>
  16 #include <fcntl.h>
  17 #include <errno.h>
  18 #include <stdlib.h>
  19 #include <signal.h>
  20 #include <limits.h>
  21 #include <resolv.h>
  22 #include <string.h>
  23 #include <unistd.h>
  24 #include <syslog.h>
  25 #include <stdbool.h>
  26 #include <sys/time.h>
  27 #include <sys/ioctl.h>
  28 #include <sys/socket.h>
  29 #include <netinet/in.h>
  30
  31 #include <net/if.h>
  32 #include <net/ethernet.h>
  33
  34 #include "odhcp6c.h"
  35 #include "md5.h"
  36
  37
  38 #define ALL_DHCPV6_RELAYS {{{0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,\
  39                 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02}}}
  40 #define DHCPV6_CLIENT_PORT 546
  41 #define DHCPV6_SERVER_PORT 547
  42 #define DHCPV6_DUID_LLADDR 3
  43 #define DHCPV6_REQ_DELAY 1
  44
  45
  46 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
  47                 const uint8_t transaction[3], enum dhcpv6_msg type);
  48
  49 static uint32_t dhcpv6_parse_ia(void *opt, void *end);
  50
  51 static reply_handler dhcpv6_handle_reply;
  52 static reply_handler dhcpv6_handle_advert;
  53 static reply_handler dhcpv6_handle_rebind_reply;
  54 static reply_handler dhcpv6_handle_reconfigure;
  55 static int dhcpv6_commit_advert(void);
  56
  57
  58
  59 // RFC 3315 - 5.5 Timeout and Delay values
  60 static struct dhcpv6_retx dhcpv6_retx[_DHCPV6_MSG_MAX] = {
  61         [DHCPV6_MSG_UNKNOWN] = {false, 1, 120, "<POLL>",
  62                         dhcpv6_handle_reconfigure, NULL},
  63         [DHCPV6_MSG_SOLICIT] = {true, 1, 3600, "SOLICIT",
  64                         dhcpv6_handle_advert, dhcpv6_commit_advert},
  65         [DHCPV6_MSG_REQUEST] = {true, 1, 30, "REQUEST",
  66                         dhcpv6_handle_reply, NULL},
  67         [DHCPV6_MSG_RENEW] = {false, 10, 600, "RENEW",
  68                         dhcpv6_handle_reply, NULL},
  69         [DHCPV6_MSG_REBIND] = {false, 10, 600, "REBIND",
  70                         dhcpv6_handle_rebind_reply, NULL},
  71         [DHCPV6_MSG_RELEASE] = {false, 1, 600, "RELEASE", NULL, NULL},
  72         [DHCPV6_MSG_DECLINE] = {false, 1, 3, "DECLINE", NULL, NULL},
  73         [DHCPV6_MSG_INFO_REQ] = {true, 1, 120, "INFOREQ",
  74                         dhcpv6_handle_reply, NULL},
  75 };
  76
  77
  78 // Sockets
  79 static int sock = -1;
  80 static int ifindex = -1;
  81 static int64_t t1 = 0, t2 = 0, t3 = 0;
  82
  83 // IA states
  84 static int request_prefix = -1;
  85 static enum odhcp6c_ia_mode na_mode = IA_MODE_NONE, pd_mode = IA_MODE_NONE;
  86 static bool accept_reconfig = false;
  87
  88 // Reconfigure key
  89 static uint8_t reconf_key[16];
  90
  91
  92
  93 int init_dhcpv6(const char *ifname, int request_pd)
  94 {
  95         request_prefix = request_pd;
  96
  97         sock = socket(AF_INET6, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  98
  99         // Detect interface
 100         struct ifreq ifr;
 101         strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
 102         if (ioctl(sock, SIOCGIFINDEX, &ifr))
 103                 return -1;
 104         ifindex = ifr.ifr_ifindex;
 105
 106         // Create client DUID
 107         size_t client_id_len;
 108         odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 109         if (client_id_len == 0) {
 110                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 111                 uint8_t duid[14] = {0, DHCPV6_OPT_CLIENTID, 0, 10, 0,
 112                                 DHCPV6_DUID_LLADDR, 0, 1};
 113                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data, ETHER_ADDR_LEN);
 114
 115                 uint8_t zero[ETHER_ADDR_LEN] = {0, 0, 0, 0, 0, 0};
 116                 struct ifreq ifs[100], *ifp, *ifend;
 117                 struct ifconf ifc;
 118                 ifc.ifc_req = ifs;
 119                 ifc.ifc_len = sizeof(ifs);
 120
 121                 if (!memcmp(&duid[8], zero, ETHER_ADDR_LEN) &&
 122                                 ioctl(sock, SIOCGIFCONF, &ifc) >= 0) {
 123                         // If our interface doesn't have an address...
 124                         ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
 125                         for (ifp = ifc.ifc_req; ifp < ifend &&
 126                                         !memcmp(&duid[8], zero, 6); ifp++) {
 127                                 memcpy(ifr.ifr_name, ifp->ifr_name,
 128                                                 sizeof(ifr.ifr_name));
 129                                 ioctl(sock, SIOCGIFHWADDR, &ifr);
 130                                 memcpy(&duid[8], ifr.ifr_hwaddr.sa_data,
 131                                                 ETHER_ADDR_LEN);
 132                         }
 133                 }
 134
 135                 odhcp6c_add_state(STATE_CLIENT_ID, duid, sizeof(duid));
 136         }
 137
 138         // Create ORO
 139         uint16_t oro[] = {
 140                         htons(DHCPV6_OPT_SIP_SERVER_D),
 141                         htons(DHCPV6_OPT_SIP_SERVER_A),
 142                         htons(DHCPV6_OPT_DNS_SERVERS),
 143                         htons(DHCPV6_OPT_DNS_DOMAIN),
 144                         htons(DHCPV6_OPT_NTP_SERVER),
 145                         htons(DHCPV6_OPT_SIP_SERVER_A),
 146                         htons(DHCPV6_OPT_AFTR_NAME),
 147                         htons(DHCPV6_OPT_PD_EXCLUDE),
 148 #ifdef EXT_PREFIX_CLASS
 149                         htons(DHCPV6_OPT_PREFIX_CLASS),
 150 #endif
 151         };
 152         odhcp6c_add_state(STATE_ORO, oro, sizeof(oro));
 153
 154
 155         // Configure IPv6-options
 156         int val = 1;
 157         setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, &val, sizeof(val));
 158         setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &val, sizeof(val));
 159         setsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, ifname, strlen(ifname));
 160
 161         struct sockaddr_in6 client_addr = { .sin6_family = AF_INET6,
 162                 .sin6_port = htons(DHCPV6_CLIENT_PORT), .sin6_flowinfo = 0 };
 163         if (bind(sock, (struct sockaddr*)&client_addr, sizeof(client_addr)))
 164                 return -1;
 165
 166         return 0;
 167 }
 168
 169
 170 void dhcpv6_set_ia_mode(enum odhcp6c_ia_mode na, enum odhcp6c_ia_mode pd)
 171 {
 172         na_mode = na;
 173         pd_mode = pd;
 174 }
 175
 176
 177 static void dhcpv6_send(enum dhcpv6_msg type, uint8_t trid[3], uint32_t ecs)
 178 {
 179         // Build FQDN
 180         char fqdn_buf[256];
 181         gethostname(fqdn_buf, sizeof(fqdn_buf));
 182         struct {
 183                 uint16_t type;
 184                 uint16_t len;
 185                 uint8_t flags;
 186                 uint8_t data[256];
 187         } fqdn;
 188         size_t fqdn_len = 5 + dn_comp(fqdn_buf, fqdn.data,
 189                         sizeof(fqdn.data), NULL, NULL);
 190         fqdn.type = htons(DHCPV6_OPT_FQDN);
 191         fqdn.len = htons(fqdn_len - 4);
 192         fqdn.flags = 0;
 193
 194
 195         // Build Client ID
 196         size_t cl_id_len;
 197         void *cl_id = odhcp6c_get_state(STATE_CLIENT_ID, &cl_id_len);
 198
 199         // Get Server ID
 200         size_t srv_id_len;
 201         void *srv_id = odhcp6c_get_state(STATE_SERVER_ID, &srv_id_len);
 202
 203         // Build IA_PDs
 204         size_t ia_pd_entries, ia_pd_len = 0;
 205         struct odhcp6c_entry *e = odhcp6c_get_state(STATE_IA_PD, &ia_pd_entries);
 206         ia_pd_entries /= sizeof(*e);
 207         struct dhcpv6_ia_hdr hdr_ia_pd = {
 208                 htons(DHCPV6_OPT_IA_PD),
 209                 htons(sizeof(hdr_ia_pd) - 4),
 210                 1, 0, 0
 211         };
 212
 213
 214         uint8_t *ia_pd = alloca(ia_pd_entries * (sizeof(struct dhcpv6_ia_prefix) + 10));
 215         for (size_t i = 0; i < ia_pd_entries; ++i) {
 216                 uint8_t ex_len = 0;
 217                 if (e[i].priority > 0)
 218                         ex_len = ((e[i].priority - e[i].length - 1) / 8) + 6;
 219
 220                 struct dhcpv6_ia_prefix p = {
 221                         .type = htons(DHCPV6_OPT_IA_PREFIX),
 222                         .len = htons(sizeof(p) - 4U + ex_len),
 223                         .prefix = e[i].length,
 224                         .addr = e[i].target
 225                 };
 226
 227                 memcpy(ia_pd + ia_pd_len, &p, sizeof(p));
 228                 ia_pd_len += sizeof(p);
 229
 230                 if (ex_len) {
 231                         ia_pd[ia_pd_len++] = 0;
 232                         ia_pd[ia_pd_len++] = DHCPV6_OPT_PD_EXCLUDE;
 233                         ia_pd[ia_pd_len++] = 0;
 234                         ia_pd[ia_pd_len++] = ex_len - 4;
 235                         ia_pd[ia_pd_len++] = e[i].priority;
 236
 237                         uint32_t excl = ntohl(e[i].router.s6_addr32[1]);
 238                         excl >>= (64 - e[i].priority);
 239                         excl <<= 8 - ((e[i].priority - e[i].length) % 8);
 240
 241                         for (size_t i = ex_len - 5; i > 0; --i, excl >>= 8)
 242                                 ia_pd[ia_pd_len + i] = excl & 0xff;
 243                         ia_pd_len += ex_len - 5;
 244                 }
 245         }
 246
 247         struct dhcpv6_ia_prefix pref = {
 248                 .type = htons(DHCPV6_OPT_IA_PREFIX),
 249                 .len = htons(25), .prefix = request_prefix
 250         };
 251         if (request_prefix > 0 && ia_pd_len == 0 && type == DHCPV6_MSG_SOLICIT) {
 252                 ia_pd = (uint8_t*)&pref;
 253                 ia_pd_len = sizeof(pref);
 254         }
 255         hdr_ia_pd.len = htons(ntohs(hdr_ia_pd.len) + ia_pd_len);
 256
 257         // Build IA_NAs
 258         size_t ia_na_entries, ia_na_len = 0;
 259         void *ia_na = NULL;
 260         e = odhcp6c_get_state(STATE_IA_NA, &ia_na_entries);
 261         ia_na_entries /= sizeof(*e);
 262
 263         struct dhcpv6_ia_hdr hdr_ia_na = {
 264                 htons(DHCPV6_OPT_IA_NA),
 265                 htons(sizeof(hdr_ia_na) - 4),
 266                 1, 0, 0
 267         };
 268
 269         struct dhcpv6_ia_addr pa[ia_na_entries];
 270         for (size_t i = 0; i < ia_na_entries; ++i) {
 271                 pa[i].type = htons(DHCPV6_OPT_IA_ADDR);
 272                 pa[i].len = htons(sizeof(pa[i]) - 4U);
 273                 pa[i].addr = e[i].target;
 274                 pa[i].preferred = 0;
 275                 pa[i].valid = 0;
 276         }
 277
 278         ia_na = pa;
 279         ia_na_len = sizeof(pa);
 280         hdr_ia_na.len = htons(ntohs(hdr_ia_na.len) + ia_na_len);
 281
 282         // Reconfigure Accept
 283         struct {
 284                 uint16_t type;
 285                 uint16_t length;
 286         } reconf_accept = {htons(DHCPV6_OPT_RECONF_ACCEPT), 0};
 287
 288         // Request Information Refresh
 289         uint16_t oro_refresh = htons(DHCPV6_OPT_INFO_REFRESH);
 290
 291         // Prepare Header
 292         size_t oro_len;
 293         void *oro = odhcp6c_get_state(STATE_ORO, &oro_len);
 294         struct {
 295                 uint8_t type;
 296                 uint8_t trid[3];
 297                 uint16_t elapsed_type;
 298                 uint16_t elapsed_len;
 299                 uint16_t elapsed_value;
 300                 uint16_t oro_type;
 301                 uint16_t oro_len;
 302         } hdr = {
 303                 type, {trid[0], trid[1], trid[2]},
 304                 htons(DHCPV6_OPT_ELAPSED), htons(2),
 305                         htons((ecs > 0xffff) ? 0xffff : ecs),
 306                 htons(DHCPV6_OPT_ORO), htons(oro_len),
 307         };
 308
 309         struct iovec iov[] = {
 310                 {&hdr, sizeof(hdr)},
 311                 {oro, oro_len},
 312                 {&oro_refresh, 0},
 313                 {cl_id, cl_id_len},
 314                 {srv_id, srv_id_len},
 315                 {&reconf_accept, sizeof(reconf_accept)},
 316                 {&fqdn, fqdn_len},
 317                 {&hdr_ia_na, sizeof(hdr_ia_na)},
 318                 {ia_na, ia_na_len},
 319                 {&hdr_ia_pd, sizeof(hdr_ia_pd)},
 320                 {ia_pd, ia_pd_len},
 321         };
 322
 323         size_t cnt = ARRAY_SIZE(iov);
 324         if (type == DHCPV6_MSG_INFO_REQ) {
 325                 cnt = 5;
 326                 iov[2].iov_len = sizeof(oro_refresh);
 327                 hdr.oro_len = htons(oro_len + sizeof(oro_refresh));
 328         } else if (!request_prefix) {
 329                 cnt = 9;
 330         }
 331
 332         // Disable IAs if not used
 333         if (type != DHCPV6_MSG_SOLICIT) {
 334                 iov[5].iov_len = 0;
 335                 if (ia_na_len == 0)
 336                         iov[7].iov_len = 0;
 337                 if (ia_pd_len == 0)
 338                         iov[9].iov_len = 0;
 339         }
 340
 341         if (na_mode == IA_MODE_NONE)
 342                 iov[7].iov_len = 0;
 343
 344         struct sockaddr_in6 srv = {AF_INET6, htons(DHCPV6_SERVER_PORT),
 345                 0, ALL_DHCPV6_RELAYS, ifindex};
 346         struct msghdr msg = {&srv, sizeof(srv), iov, cnt, NULL, 0, 0};
 347
 348         sendmsg(sock, &msg, 0);
 349 }
 350
 351
 352 static int64_t dhcpv6_rand_delay(int64_t time)
 353 {
 354         int random;
 355         odhcp6c_random(&random, sizeof(random));
 356         return (time * ((int64_t)random % 1000LL)) / 10000LL;
 357 }
 358
 359
 360 int dhcpv6_request(enum dhcpv6_msg type)
 361 {
 362         uint8_t buf[1536];
 363         uint64_t timeout = UINT32_MAX;
 364         struct dhcpv6_retx *retx = &dhcpv6_retx[type];
 365
 366         if (retx->delay) {
 367                 struct timespec ts = {0, 0};
 368                 ts.tv_nsec = dhcpv6_rand_delay(10 * DHCPV6_REQ_DELAY);
 369                 nanosleep(&ts, NULL);
 370         }
 371
 372         if (type == DHCPV6_MSG_REQUEST)
 373                 timeout = 60;
 374         else if (type == DHCPV6_MSG_RELEASE || type == DHCPV6_MSG_DECLINE)
 375                 timeout = 3;
 376         else if (type == DHCPV6_MSG_UNKNOWN)
 377                 timeout = t1;
 378         else if (type == DHCPV6_MSG_RENEW)
 379                 timeout = (t2 > t1) ? t2 - t1 : 0;
 380         else if (type == DHCPV6_MSG_REBIND)
 381                 timeout = (t3 > t2) ? t3 - t2 : 0;
 382
 383         if (timeout == 0)
 384                 return -1;
 385
 386         syslog(LOG_NOTICE, "Sending %s (timeout %us)", retx->name, (unsigned)timeout);
 387
 388         uint64_t start = odhcp6c_get_milli_time(), round_start = start, elapsed;
 389
 390         // Generate transaction ID
 391         uint8_t trid[3] = {0, 0, 0};
 392         if (type != DHCPV6_MSG_UNKNOWN)
 393                 odhcp6c_random(trid, sizeof(trid));
 394         ssize_t len = -1;
 395         int64_t rto = 0;
 396
 397         do {
 398                 rto = (rto == 0) ? (retx->init_timeo * 1000 +
 399                                 dhcpv6_rand_delay(retx->init_timeo * 1000)) :
 400                                 (2 * rto + dhcpv6_rand_delay(rto));
 401
 402                 if (rto >= retx->max_timeo * 1000)
 403                         rto = retx->max_timeo * 1000 +
 404                                 dhcpv6_rand_delay(retx->max_timeo * 1000);
 405
 406                 // Calculate end for this round and elapsed time
 407                 uint64_t round_end = round_start + rto;
 408                 elapsed = round_start - start;
 409
 410                 // Don't wait too long
 411                 if (round_end - start > timeout * 1000)
 412                         round_end = timeout * 1000 + start;
 413
 414                 // Built and send package
 415                 if (type != DHCPV6_MSG_UNKNOWN)
 416                         dhcpv6_send(type, trid, elapsed / 10);
 417
 418                 // Receive rounds
 419                 for (; len < 0 && round_start < round_end;
 420                                 round_start = odhcp6c_get_milli_time()) {
 421                         // Check for pending signal
 422                         if (odhcp6c_signal_process())
 423                                 return -1;
 424
 425                         // Set timeout for receiving
 426                         uint64_t t = round_end - round_start;
 427                         struct timeval timeout = {t / 1000, (t % 1000) * 1000};
 428                         setsockopt(sock, SOL_SOCKET, SO_RCVTIMEO,
 429                                         &timeout, sizeof(timeout));
 430
 431                         // Receive cycle
 432                         len = recv(sock, buf, sizeof(buf), 0);
 433
 434                         if (!dhcpv6_response_is_valid(buf, len, trid, type))
 435                                 len = -1;
 436
 437                         if (len > 0) {
 438                                 uint8_t *opt = &buf[4];
 439                                 uint8_t *opt_end = opt + len - 4;
 440
 441                                 round_start = odhcp6c_get_milli_time();
 442                                 elapsed = round_start - start;
 443                                 syslog(LOG_NOTICE, "Got a valid reply after "
 444                                                 "%ums", (unsigned)elapsed);
 445
 446                                 if (retx->handler_reply)
 447                                         len = retx->handler_reply(
 448                                                         type, opt, opt_end);
 449
 450                                 if (len > 0 && round_end - round_start > 1000)
 451                                         round_end = 1000 + round_start;
 452                         }
 453                 }
 454
 455                 // Allow
 456                 if (retx->handler_finish)
 457                         len = retx->handler_finish();
 458         } while (len < 0 && elapsed / 1000 < timeout);
 459
 460         return len;
 461 }
 462
 463
 464 static bool dhcpv6_response_is_valid(const void *buf, ssize_t len,
 465                 const uint8_t transaction[3], enum dhcpv6_msg type)
 466 {
 467         const struct dhcpv6_header *rep = buf;
 468         if (len < (ssize_t)sizeof(*rep) || memcmp(rep->tr_id,
 469                         transaction, sizeof(rep->tr_id)))
 470                 return false; // Invalid reply
 471
 472         if (type == DHCPV6_MSG_SOLICIT) {
 473                 if (rep->msg_type != DHCPV6_MSG_ADVERT &&
 474                                 rep->msg_type != DHCPV6_MSG_REPLY)
 475                         return false;
 476         } else if (type == DHCPV6_MSG_UNKNOWN) {
 477                 if (!accept_reconfig || rep->msg_type != DHCPV6_MSG_RECONF)
 478                         return false;
 479         } else if (rep->msg_type != DHCPV6_MSG_REPLY) {
 480                 return false;
 481         }
 482
 483         uint8_t *end = ((uint8_t*)buf) + len, *odata;
 484         uint16_t otype, olen;
 485         bool clientid_ok = false, serverid_ok = false, rcauth_ok = false;
 486
 487         size_t client_id_len, server_id_len;
 488         void *client_id = odhcp6c_get_state(STATE_CLIENT_ID, &client_id_len);
 489         void *server_id = odhcp6c_get_state(STATE_SERVER_ID, &server_id_len);
 490
 491         dhcpv6_for_each_option(&rep[1], end, otype, olen, odata) {
 492                 if (otype == DHCPV6_OPT_CLIENTID) {
 493                         clientid_ok = (olen + 4U == client_id_len) && !memcmp(
 494                                         &odata[-4], client_id, client_id_len);
 495                 } else if (otype == DHCPV6_OPT_SERVERID) {
 496                         serverid_ok = (olen + 4U == server_id_len) && !memcmp(
 497                                         &odata[-4], server_id, server_id_len);
 498                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 499                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 500                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 501                         if (r->protocol != 3 || r->algorithm != 1 || r->reconf_type != 2)
 502                                 continue;
 503
 504                         md5_state_t md5;
 505                         uint8_t serverhash[16], secretbytes[16], hash[16];
 506                         memcpy(serverhash, r->key, sizeof(serverhash));
 507                         memset(r->key, 0, sizeof(r->key));
 508                         memcpy(secretbytes, reconf_key, sizeof(secretbytes));
 509
 510                         for (size_t i = 0; i < sizeof(secretbytes); ++i)
 511                                 secretbytes[i] ^= 0x36;
 512
 513                         md5_init(&md5);
 514                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 515                         md5_append(&md5, buf, len);
 516                         md5_finish(&md5, hash);
 517
 518                         for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 519                                 secretbytes[i] ^= 0x36;
 520                                 secretbytes[i] ^= 0x5c;
 521                         }
 522
 523                         md5_init(&md5);
 524                         md5_append(&md5, secretbytes, sizeof(secretbytes));
 525                         md5_append(&md5, hash, 16);
 526                         md5_finish(&md5, hash);
 527
 528                         rcauth_ok = !memcmp(hash, serverhash, sizeof(hash));
 529                 }
 530         }
 531
 532         if (rep->msg_type == DHCPV6_MSG_RECONF && !rcauth_ok)
 533                 return false;
 534
 535         return clientid_ok && (serverid_ok || server_id_len == 0);
 536 }
 537
 538
 539 int dhcpv6_poll_reconfigure(void)
 540 {
 541         int ret = dhcpv6_request(DHCPV6_MSG_UNKNOWN);
 542         if (ret != -1)
 543                 ret = dhcpv6_request(ret);
 544
 545         return ret;
 546 }
 547
 548
 549 static int dhcpv6_handle_reconfigure(_unused enum dhcpv6_msg orig,
 550                 const void *opt, const void *end)
 551 {
 552         // TODO: should verify the reconfigure message
 553         uint16_t otype, olen;
 554         uint8_t *odata, msg = DHCPV6_MSG_RENEW;
 555         dhcpv6_for_each_option(opt, end, otype, olen, odata)
 556                 if (otype == DHCPV6_OPT_RECONF_MESSAGE && olen == 1 && (
 557                                 odata[0] == DHCPV6_MSG_RENEW ||
 558                                 odata[0] == DHCPV6_MSG_INFO_REQ))
 559                         msg = odata[0];
 560
 561         dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 562         return msg;
 563 }
 564
 565
 566 // Collect all advertised servers
 567 static int dhcpv6_handle_advert(enum dhcpv6_msg orig,
 568                 const void *opt, const void *end)
 569 {
 570         uint16_t olen, otype;
 571         uint8_t *odata;
 572         struct dhcpv6_server_cand cand = {false, false, 0, 0, {0}, NULL, NULL, 0, 0};
 573         bool have_na = false, have_pd = false;
 574
 575         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 576                 if (orig == DHCPV6_MSG_SOLICIT &&
 577                                 (otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA) &&
 578                                 olen > sizeof(struct dhcpv6_ia_hdr)) {
 579                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 580                         dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 581                 }
 582
 583                 if (otype == DHCPV6_OPT_SERVERID && olen <= 130) {
 584                         memcpy(cand.duid, odata, olen);
 585                         cand.duid_len = olen;
 586                 } else if (otype == DHCPV6_OPT_STATUS && olen >= 2 && !odata[0]
 587                                 && odata[1] == DHCPV6_NoPrefixAvail) {
 588                         cand.preference -= 2000;
 589                 } else if (otype == DHCPV6_OPT_PREF && olen >= 1 &&
 590                                 cand.preference >= 0) {
 591                         cand.preference = odata[0];
 592                 } else if (otype == DHCPV6_OPT_RECONF_ACCEPT) {
 593                         cand.wants_reconfigure = true;
 594                 } else if (otype == DHCPV6_OPT_IA_PD && request_prefix) {
 595                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 596                         uint8_t *oend = odata + olen, *d;
 597                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d)
 598                                 if (otype == DHCPV6_OPT_IA_PREFIX)
 599                                         have_pd = true;
 600                 } else if (otype == DHCPV6_OPT_IA_NA) {
 601                         struct dhcpv6_ia_hdr *h = (struct dhcpv6_ia_hdr*)&odata[-4];
 602                         uint8_t *oend = odata + olen, *d;
 603                         dhcpv6_for_each_option(&h[1], oend, otype, olen, d)
 604                                 if (otype == DHCPV6_OPT_IA_ADDR)
 605                                         have_na = true;
 606                 }
 607         }
 608
 609         if ((!have_na && na_mode == IA_MODE_FORCE) ||
 610                         (!have_pd && pd_mode == IA_MODE_FORCE))
 611                 return -1;
 612
 613         if (na_mode != IA_MODE_NONE && !have_na) {
 614                 cand.has_noaddravail = true;
 615                 cand.preference -= 1000;
 616         }
 617
 618         if (pd_mode != IA_MODE_NONE) {
 619                 if (have_pd)
 620                         cand.preference += 2000;
 621                 else
 622                         cand.preference -= 2000;
 623         }
 624
 625         if (cand.duid_len > 0) {
 626                 cand.ia_na = odhcp6c_move_state(STATE_IA_NA, &cand.ia_na_len);
 627                 cand.ia_pd = odhcp6c_move_state(STATE_IA_PD, &cand.ia_pd_len);
 628                 odhcp6c_add_state(STATE_SERVER_CAND, &cand, sizeof(cand));
 629         }
 630
 631         if (orig == DHCPV6_MSG_SOLICIT) {
 632                 odhcp6c_clear_state(STATE_IA_NA);
 633                 odhcp6c_clear_state(STATE_IA_PD);
 634         }
 635
 636         return -1;
 637 }
 638
 639
 640 static int dhcpv6_commit_advert(void)
 641 {
 642         size_t cand_len;
 643         struct dhcpv6_server_cand *c = NULL, *cand =
 644                         odhcp6c_get_state(STATE_SERVER_CAND, &cand_len);
 645
 646         bool retry = false;
 647         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 648                 if (cand[i].has_noaddravail)
 649                         retry = true; // We want to try again
 650
 651                 if (!c || c->preference < cand[i].preference)
 652                         c = &cand[i];
 653         }
 654
 655         if (retry && na_mode == IA_MODE_TRY) {
 656                 // We give it a second try without the IA_NA
 657                 na_mode = IA_MODE_NONE;
 658                 return dhcpv6_request(DHCPV6_MSG_SOLICIT);
 659         }
 660
 661         if (c) {
 662                 uint16_t hdr[2] = {htons(DHCPV6_OPT_SERVERID),
 663                                 htons(c->duid_len)};
 664                 odhcp6c_add_state(STATE_SERVER_ID, hdr, sizeof(hdr));
 665                 odhcp6c_add_state(STATE_SERVER_ID, c->duid, c->duid_len);
 666                 accept_reconfig = c->wants_reconfigure;
 667                 odhcp6c_add_state(STATE_IA_NA, c->ia_na, c->ia_na_len);
 668                 odhcp6c_add_state(STATE_IA_PD, c->ia_pd, c->ia_pd_len);
 669         }
 670
 671         for (size_t i = 0; i < cand_len / sizeof(*c); ++i) {
 672                 free(cand[i].ia_na);
 673                 free(cand[i].ia_pd);
 674         }
 675         odhcp6c_clear_state(STATE_SERVER_CAND);
 676
 677         if (!c)
 678                 return -1;
 679         else if (request_prefix || na_mode != IA_MODE_NONE)
 680                 return DHCPV6_STATEFUL;
 681         else
 682                 return DHCPV6_STATELESS;
 683 }
 684
 685
 686 static int dhcpv6_handle_rebind_reply(enum dhcpv6_msg orig,
 687                 const void *opt, const void *end)
 688 {
 689         dhcpv6_handle_advert(orig, opt, end);
 690         if (dhcpv6_commit_advert() < 0) {
 691                 dhcpv6_handle_reply(DHCPV6_MSG_UNKNOWN, NULL, NULL);
 692                 return -1;
 693         }
 694
 695         return dhcpv6_handle_reply(orig, opt, end);
 696 }
 697
 698
 699 static int dhcpv6_handle_reply(enum dhcpv6_msg orig,
 700                 const void *opt, const void *end)
 701 {
 702         uint8_t *odata;
 703         uint16_t otype, olen;
 704
 705         odhcp6c_expire();
 706
 707         if (orig == DHCPV6_MSG_UNKNOWN) {
 708                 static time_t last_update = 0;
 709                 time_t now = odhcp6c_get_milli_time() / 1000;
 710
 711                 uint32_t elapsed = (last_update > 0) ? now - last_update : 0;
 712                 last_update = now;
 713
 714                 t1 -= elapsed;
 715                 t2 -= elapsed;
 716                 t3 -= elapsed;
 717
 718                 if (t1 < 0)
 719                         t1 = 0;
 720
 721                 if (t2 < 0)
 722                         t2 = 0;
 723
 724                 if (t3 < 0)
 725                         t3 = 0;
 726         } else {
 727                 t1 = t2 = t3 = UINT32_MAX;
 728         }
 729
 730         if (orig == DHCPV6_MSG_REQUEST) {
 731                 // Delete NA and PD we have in the state from the Advert
 732                 odhcp6c_clear_state(STATE_IA_NA);
 733                 odhcp6c_clear_state(STATE_IA_PD);
 734         }
 735
 736         if (opt) {
 737                 odhcp6c_clear_state(STATE_DNS);
 738                 odhcp6c_clear_state(STATE_SEARCH);
 739                 odhcp6c_clear_state(STATE_SNTP_IP);
 740                 odhcp6c_clear_state(STATE_SNTP_FQDN);
 741                 odhcp6c_clear_state(STATE_SIP_IP);
 742                 odhcp6c_clear_state(STATE_SIP_FQDN);
 743                 odhcp6c_clear_state(STATE_AFTR_NAME);
 744         }
 745
 746         // Parse and find all matching IAs
 747         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 748                 if ((otype == DHCPV6_OPT_IA_PD || otype == DHCPV6_OPT_IA_NA)
 749                                 && olen > sizeof(struct dhcpv6_ia_hdr)) {
 750                         struct dhcpv6_ia_hdr *ia_hdr = (void*)(&odata[-4]);
 751                         uint32_t l_t1 = ntohl(ia_hdr->t1);
 752                         uint32_t l_t2 = ntohl(ia_hdr->t2);
 753
 754                         // Test ID and T1-T2 validity
 755                         if (ia_hdr->iaid != 1 || l_t2 < l_t1)
 756                                 continue;
 757
 758                         int error = 0;
 759                         uint16_t stype, slen;
 760                         uint8_t *sdata;
 761                         // Test status and bail if error
 762                         dhcpv6_for_each_option(&ia_hdr[1], odata + olen,
 763                                         stype, slen, sdata)
 764                                 if (stype == DHCPV6_OPT_STATUS && slen >= 2)
 765                                         error = ((int)sdata[0]) << 8 | ((int)sdata[1]);
 766
 767                         if (error) {
 768                                 syslog(LOG_WARNING, "Server returned IAID status %i!", error);
 769                                 if (error != 2)
 770                                         raise(SIGUSR2);
 771                                 break;
 772                         }
 773
 774                         uint32_t n = dhcpv6_parse_ia(&ia_hdr[1], odata + olen);
 775
 776                         if (!l_t1)
 777                                 l_t1 = 300;
 778
 779                         if (!l_t2)
 780                                 l_t2 = 600;
 781
 782                         if (n < t3)
 783                                 t3 = n;
 784
 785                         // Update times
 786                         if (l_t1 > 0 && t1 > l_t1)
 787                                 t1 = l_t1;
 788
 789                         if (l_t2 > 0 && t2 > l_t2)
 790                                 t2 = l_t2;
 791
 792                 } else if (otype == DHCPV6_OPT_DNS_SERVERS) {
 793                         if (olen % 16 == 0)
 794                                 odhcp6c_add_state(STATE_DNS, odata, olen);
 795                 } else if (otype == DHCPV6_OPT_DNS_DOMAIN) {
 796                         odhcp6c_add_state(STATE_SEARCH, odata, olen);
 797                 } else if (otype == DHCPV6_OPT_NTP_SERVER) {
 798                         uint16_t stype, slen;
 799                         uint8_t *sdata;
 800                         // Test status and bail if error
 801                         dhcpv6_for_each_option(odata, odata + olen,
 802                                         stype, slen, sdata) {
 803                                 if (slen == 16 && (stype == NTP_MC_ADDR ||
 804                                                 stype == NTP_SRV_ADDR))
 805                                         odhcp6c_add_state(STATE_SNTP_IP,
 806                                                         sdata, slen);
 807                                 else if (slen > 0 && stype == NTP_SRV_FQDN)
 808                                         odhcp6c_add_state(STATE_SNTP_FQDN,
 809                                                         sdata, slen);
 810                         }
 811                 } else if (otype == DHCPV6_OPT_SIP_SERVER_A) {
 812                         if (olen == 16)
 813                                 odhcp6c_add_state(STATE_SIP_IP, odata, olen);
 814                 } else if (otype == DHCPV6_OPT_SIP_SERVER_D) {
 815                         odhcp6c_add_state(STATE_SIP_FQDN, odata, olen);
 816                 } else if (otype == DHCPV6_OPT_INFO_REFRESH && olen >= 4) {
 817                         uint32_t refresh = ntohl(*((uint32_t*)odata));
 818                         if (refresh < (uint32_t)t1)
 819                                 t1 = refresh;
 820                 } else if (otype == DHCPV6_OPT_AUTH && olen == -4 +
 821                                 sizeof(struct dhcpv6_auth_reconfigure)) {
 822                         struct dhcpv6_auth_reconfigure *r = (void*)&odata[-4];
 823                         if (r->protocol == 3 && r->algorithm == 1 &&
 824                                         r->reconf_type == 1)
 825                                 memcpy(reconf_key, r->key, sizeof(r->key));
 826                 } else if (otype == DHCPV6_OPT_AFTR_NAME && olen > 3) {
 827                         size_t cur_len;
 828                         odhcp6c_get_state(STATE_AFTR_NAME, &cur_len);
 829                         if (cur_len == 0)
 830                                 odhcp6c_add_state(STATE_AFTR_NAME, odata, olen);
 831                 } else if (otype != DHCPV6_OPT_CLIENTID &&
 832                                 otype != DHCPV6_OPT_SERVERID) {
 833                         odhcp6c_add_state(STATE_CUSTOM_OPTS,
 834                                         &odata[-4], olen + 4);
 835                 }
 836         }
 837
 838         if (t1 == UINT32_MAX)
 839                 t1 = 300;
 840
 841         if (t2 == UINT32_MAX)
 842                 t2 = 600;
 843
 844         if (t3 == UINT32_MAX)
 845                 t3 = 3600;
 846
 847         return true;
 848 }
 849
 850
 851 static uint32_t dhcpv6_parse_ia(void *opt, void *end)
 852 {
 853         uint32_t timeout = UINT32_MAX; // Minimum timeout
 854         uint16_t otype, olen;
 855         uint8_t *odata;
 856
 857         // Update address IA
 858         dhcpv6_for_each_option(opt, end, otype, olen, odata) {
 859                 struct odhcp6c_entry entry = {IN6ADDR_ANY_INIT, 0, 0,
 860                                 IN6ADDR_ANY_INIT, 0, 0, 0};
 861
 862                 if (otype == DHCPV6_OPT_IA_PREFIX) {
 863                         struct dhcpv6_ia_prefix *prefix = (void*)&odata[-4];
 864                         if (olen + 4U < sizeof(*prefix))
 865                                 continue;
 866
 867                         entry.valid = ntohl(prefix->valid);
 868                         entry.preferred = ntohl(prefix->preferred);
 869
 870                         if (entry.preferred > entry.valid)
 871                                 continue;
 872
 873                         entry.length = prefix->prefix;
 874                         entry.target = prefix->addr;
 875                         uint16_t stype, slen;
 876                         uint8_t *sdata;
 877
 878 #ifdef EXT_PREFIX_CLASS
 879                         // Find prefix class, if any
 880                         dhcpv6_for_each_option(&prefix[1], odata + olen,
 881                                         stype, slen, sdata)
 882                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 883                                         entry.class = sdata[0] << 8 | sdata[1];
 884 #endif
 885
 886                         // Parse PD-exclude
 887                         bool ok = true;
 888                         dhcpv6_for_each_option(odata + sizeof(*prefix) - 4U,
 889                                         odata + olen, stype, slen, sdata) {
 890                                 if (stype != DHCPV6_OPT_PD_EXCLUDE || slen < 2)
 891                                         continue;
 892
 893                                 uint8_t elen = sdata[0];
 894                                 if (elen > 64)
 895                                         elen = 64;
 896
 897                                 if (elen <= 32 || elen <= entry.length) {
 898                                         ok = false;
 899                                         continue;
 900                                 }
 901
 902
 903                                 uint8_t bytes = ((elen - entry.length - 1) / 8) + 1;
 904                                 if (slen <= bytes) {
 905                                         ok = false;
 906                                         continue;
 907                                 }
 908
 909                                 uint32_t exclude = 0;
 910                                 do {
 911                                         exclude = exclude << 8 | sdata[bytes];
 912                                 } while (--bytes);
 913
 914                                 exclude >>= 8 - ((elen - entry.length) % 8);
 915                                 exclude <<= 64 - elen;
 916
 917                                 // Abusing router & priority fields for exclusion
 918                                 entry.router = entry.target;
 919                                 entry.router.s6_addr32[1] |= htonl(exclude);
 920                                 entry.priority = elen;
 921                         }
 922
 923                         if (ok)
 924                                 odhcp6c_update_entry(STATE_IA_PD, &entry);
 925
 926                         entry.priority = 0;
 927                         memset(&entry.router, 0, sizeof(entry.router));
 928                 } else if (otype == DHCPV6_OPT_IA_ADDR) {
 929                         struct dhcpv6_ia_addr *addr = (void*)&odata[-4];
 930                         if (olen + 4U < sizeof(*addr))
 931                                 continue;
 932
 933                         entry.preferred = ntohl(addr->preferred);
 934                         entry.valid = ntohl(addr->valid);
 935
 936                         if (entry.preferred > entry.valid)
 937                                 continue;
 938
 939                         entry.length = 128;
 940                         entry.target = addr->addr;
 941
 942 #ifdef EXT_PREFIX_CLASS
 943                         uint16_t stype, slen;
 944                         uint8_t *sdata;
 945                         // Find prefix class, if any
 946                         dhcpv6_for_each_option(&addr[1], odata + olen,
 947                                         stype, slen, sdata)
 948                                 if (stype == DHCPV6_OPT_PREFIX_CLASS && slen == 2)
 949                                         entry.class = sdata[0] << 8 | sdata[1];
 950 #endif
 951
 952                         odhcp6c_update_entry(STATE_IA_NA, &entry);
 953                 }
 954                 if (entry.valid > 0 && timeout > entry.valid)
 955                         timeout = entry.valid;
 956         }
 957
 958         return timeout;
 959 }