src/dhcpv4.c

   1 /**
   2  * Copyright (C) 2012-2013 Steven Barth <steven@midlink.org>
   3  * Copyright (C) 2016 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 <time.h>
  18 #include <errno.h>
  19 #include <fcntl.h>
  20 #include <unistd.h>
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23 #include <resolv.h>
  24 #include <limits.h>
  25 #include <net/if.h>
  26 #include <net/if_arp.h>
  27 #include <netinet/ip.h>
  28 #include <sys/ioctl.h>
  29 #include <sys/timerfd.h>
  30 #include <arpa/inet.h>
  31
  32 #include <libubox/md5.h>
  33
  34 #include "odhcpd.h"
  35 #include "dhcpv4.h"
  36 #include "dhcpv6.h"
  37
  38 #define PACKET_SIZE(start, end) (((uint8_t *)end - (uint8_t *)start) < DHCPV4_MIN_PACKET_SIZE ? \
  39                                  DHCPV4_MIN_PACKET_SIZE : (uint8_t *)end - (uint8_t *)start)
  40 #define MAX_PREFIX_LEN 28
  41
  42 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info);
  43 static int setup_dhcpv4_addresses(struct interface *iface);
  44 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr);
  45 static void valid_until_cb(struct uloop_timeout *event);
  46 static void handle_addrlist_change(struct interface *iface);
  47 static void dhcpv4_fr_start(struct dhcp_assignment *a);
  48 static void dhcpv4_fr_rand_delay(struct dhcp_assignment *a);
  49 static void dhcpv4_fr_stop(struct dhcp_assignment *a);
  50 static void handle_dhcpv4(void *addr, void *data, size_t len,
  51                 struct interface *iface, void *dest_addr);
  52 static struct dhcp_assignment* dhcpv4_lease(struct interface *iface,
  53                 enum dhcpv4_msg msg, const uint8_t *mac, const uint32_t reqaddr,
  54                 uint32_t *leasetime, const char *hostname, const size_t hostname_len,
  55                 const bool accept_fr_nonce, bool *incl_fr_opt, uint32_t *fr_serverid,
  56                 const char *reqopts, const size_t reqopts_len);
  57
  58 static struct netevent_handler dhcpv4_netevent_handler = { .cb = dhcpv4_netevent_cb, };
  59 static struct uloop_timeout valid_until_timeout = {.cb = valid_until_cb};
  60 static uint32_t serial = 0;
  61
  62 struct odhcpd_ref_ip {
  63         struct list_head head;
  64         int ref_cnt;
  65         struct odhcpd_ipaddr addr;
  66 };
  67
  68 /* Create socket and register events */
  69 int dhcpv4_init(void)
  70 {
  71         uloop_timeout_set(&valid_until_timeout, 1000);
  72         netlink_add_netevent_handler(&dhcpv4_netevent_handler);
  73
  74         return 0;
  75 }
  76
  77 int dhcpv4_setup_interface(struct interface *iface, bool enable)
  78 {
  79         int ret = 0;
  80
  81         enable = enable && (iface->dhcpv4 != MODE_DISABLED);
  82
  83         if (iface->dhcpv4_event.uloop.fd >= 0) {
  84                 uloop_fd_delete(&iface->dhcpv4_event.uloop);
  85                 close(iface->dhcpv4_event.uloop.fd);
  86                 iface->dhcpv4_event.uloop.fd = -1;
  87         }
  88
  89         if (enable) {
  90                 struct sockaddr_in bind_addr = {AF_INET, htons(DHCPV4_SERVER_PORT),
  91                                         {INADDR_ANY}, {0}};
  92                 int val = 1;
  93
  94                 iface->dhcpv4_event.uloop.fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, IPPROTO_UDP);
  95                 if (iface->dhcpv4_event.uloop.fd < 0) {
  96                         syslog(LOG_ERR, "socket(AF_INET): %m");
  97                         ret = -1;
  98                         goto out;
  99                 }
 100
 101                 /* Basic IPv4 configuration */
 102                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_REUSEADDR,
 103                                         &val, sizeof(val)) < 0) {
 104                         syslog(LOG_ERR, "setsockopt(SO_REUSEADDR): %m");
 105                         ret = -1;
 106                         goto out;
 107                 }
 108
 109                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BROADCAST,
 110                                         &val, sizeof(val)) < 0) {
 111                         syslog(LOG_ERR, "setsockopt(SO_BROADCAST): %m");
 112                         ret = -1;
 113                         goto out;
 114                 }
 115
 116                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_PKTINFO,
 117                                         &val, sizeof(val)) < 0) {
 118                         syslog(LOG_ERR, "setsockopt(IP_PKTINFO): %m");
 119                         ret = -1;
 120                         goto out;
 121                 }
 122
 123                 val = IPTOS_PREC_INTERNETCONTROL;
 124                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_TOS,
 125                                         &val, sizeof(val)) < 0) {
 126                         syslog(LOG_ERR, "setsockopt(IP_TOS): %m");
 127                         ret = -1;
 128                         goto out;
 129                 }
 130
 131                 val = IP_PMTUDISC_DONT;
 132                 if (setsockopt(iface->dhcpv4_event.uloop.fd, IPPROTO_IP, IP_MTU_DISCOVER,
 133                                         &val, sizeof(val)) < 0) {
 134                         syslog(LOG_ERR, "setsockopt(IP_MTU_DISCOVER): %m");
 135                         ret = -1;
 136                         goto out;
 137                 }
 138
 139                 if (setsockopt(iface->dhcpv4_event.uloop.fd, SOL_SOCKET, SO_BINDTODEVICE,
 140                                         iface->ifname, strlen(iface->ifname)) < 0) {
 141                         syslog(LOG_ERR, "setsockopt(SO_BINDTODEVICE): %m");
 142                         ret = -1;
 143                         goto out;
 144                 }
 145
 146                 if (bind(iface->dhcpv4_event.uloop.fd, (struct sockaddr*)&bind_addr,
 147                                         sizeof(bind_addr)) < 0) {
 148                         syslog(LOG_ERR, "bind(): %m");
 149                         ret = -1;
 150                         goto out;
 151                 }
 152
 153                 if (setup_dhcpv4_addresses(iface) < 0) {
 154                         ret = -1;
 155                         goto out;
 156                 }
 157
 158                 iface->dhcpv4_event.handle_dgram = handle_dhcpv4;
 159                 odhcpd_register(&iface->dhcpv4_event);
 160         } else {
 161                 while (!list_empty(&iface->dhcpv4_assignments))
 162                         free_assignment(list_first_entry(&iface->dhcpv4_assignments,
 163                                                         struct dhcp_assignment, head));
 164         }
 165
 166 out:
 167         if (ret < 0 && iface->dhcpv4_event.uloop.fd >= 0) {
 168                 close(iface->dhcpv4_event.uloop.fd);
 169                 iface->dhcpv4_event.uloop.fd = -1;
 170         }
 171
 172         return ret;
 173 }
 174
 175
 176 static void dhcpv4_netevent_cb(unsigned long event, struct netevent_handler_info *info)
 177 {
 178         struct interface *iface = info->iface;
 179
 180         if (!iface || iface->dhcpv4 == MODE_DISABLED)
 181                 return;
 182
 183         switch (event) {
 184         case NETEV_IFINDEX_CHANGE:
 185                 dhcpv4_setup_interface(iface, true);
 186                 break;
 187         case NETEV_ADDRLIST_CHANGE:
 188                 handle_addrlist_change(iface);
 189                 break;
 190         default:
 191                 break;
 192         }
 193 }
 194
 195 static struct dhcp_assignment *find_assignment_by_hwaddr(struct interface *iface, const uint8_t *hwaddr)
 196 {
 197         struct dhcp_assignment *a;
 198
 199         list_for_each_entry(a, &iface->dhcpv4_assignments, head)
 200                 if (!memcmp(a->hwaddr, hwaddr, 6))
 201                         return a;
 202
 203         return NULL;
 204 }
 205
 206 static int setup_dhcpv4_addresses(struct interface *iface)
 207 {
 208         iface->dhcpv4_start_ip.s_addr = INADDR_ANY;
 209         iface->dhcpv4_end_ip.s_addr = INADDR_ANY;
 210         iface->dhcpv4_local.s_addr = INADDR_ANY;
 211         iface->dhcpv4_bcast.s_addr = INADDR_ANY;
 212         iface->dhcpv4_mask.s_addr = INADDR_ANY;
 213
 214         /* Sanity checks */
 215         if (iface->dhcpv4_start.s_addr & htonl(0xffff0000) ||
 216             iface->dhcpv4_end.s_addr & htonl(0xffff0000) ||
 217             ntohl(iface->dhcpv4_start.s_addr) > ntohl(iface->dhcpv4_end.s_addr)) {
 218                 syslog(LOG_WARNING, "Invalid DHCP range for %s", iface->name);
 219                 return -1;
 220         }
 221
 222         if (!iface->addr4_len) {
 223                 syslog(LOG_WARNING, "No network(s) available on %s", iface->name);
 224                 return -1;
 225         }
 226
 227         uint32_t start = ntohl(iface->dhcpv4_start.s_addr);
 228         uint32_t end = ntohl(iface->dhcpv4_end.s_addr);
 229
 230         for (size_t i = 0; i < iface->addr4_len && start && end; i++) {
 231                 struct in_addr *addr = &iface->addr4[i].addr.in;
 232                 struct in_addr mask;
 233
 234                 if (addr_is_fr_ip(iface, addr))
 235                         continue;
 236
 237                 odhcpd_bitlen2netmask(false, iface->addr4[i].prefix, &mask);
 238                 if ((start & ntohl(~mask.s_addr)) == start &&
 239                                 (end & ntohl(~mask.s_addr)) == end &&
 240                                 end < ntohl(~mask.s_addr)) {    /* Exclude broadcast address */
 241                         iface->dhcpv4_start_ip.s_addr = htonl(start) |
 242                                                         (addr->s_addr & mask.s_addr);
 243                         iface->dhcpv4_end_ip.s_addr = htonl(end) |
 244                                                         (addr->s_addr & mask.s_addr);
 245                         iface->dhcpv4_local = *addr;
 246                         iface->dhcpv4_bcast = iface->addr4[i].broadcast;
 247                         iface->dhcpv4_mask = mask;
 248                         return 0;
 249                 }
 250         }
 251
 252         /* Don't allocate IP range for subnets smaller than /28 */
 253         if (iface->addr4[0].prefix > MAX_PREFIX_LEN) {
 254                 syslog(LOG_WARNING, "Auto allocation of DHCP range fails on %s (prefix length must be < %d).", iface->name, MAX_PREFIX_LEN + 1);
 255                 return -1;
 256         }
 257
 258         iface->dhcpv4_local = iface->addr4[0].addr.in;
 259         iface->dhcpv4_bcast = iface->addr4[0].broadcast;
 260         odhcpd_bitlen2netmask(false, iface->addr4[0].prefix, &iface->dhcpv4_mask);
 261         end = start = iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr;
 262
 263         /* Auto allocate ranges */
 264         if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffff00) {           /* /24, 150 of 256, [100..249] */
 265                 iface->dhcpv4_start_ip.s_addr = start | htonl(100);
 266                 iface->dhcpv4_end_ip.s_addr = end | htonl(100 + 150 - 1);
 267         } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffff80) {    /* /25, 100 of 128, [20..119] */
 268                 iface->dhcpv4_start_ip.s_addr = start | htonl(20);
 269                 iface->dhcpv4_end_ip.s_addr = end | htonl(20 + 100 - 1);
 270         } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffc0) {    /* /26, 50 of 64, [10..59] */
 271                 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
 272                 iface->dhcpv4_end_ip.s_addr = end | htonl(10 + 50 - 1);
 273         } else if (ntohl(iface->dhcpv4_mask.s_addr) <= 0xffffffe0) {    /* /27, 20 of 32, [10..29] */
 274                 iface->dhcpv4_start_ip.s_addr = start | htonl(10);
 275                 iface->dhcpv4_end_ip.s_addr = end | htonl(10 + 20 - 1);
 276         } else {                                                        /* /28, 10 of 16, [3..12] */
 277                 iface->dhcpv4_start_ip.s_addr = start | htonl(3);
 278                 iface->dhcpv4_end_ip.s_addr = end | htonl(3 + 10 - 1);
 279         }
 280
 281         return 0;
 282 }
 283
 284 static void inc_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct odhcpd_ref_ip *ip)
 285 {
 286         *ptr = ip;
 287         ip->ref_cnt++;
 288 }
 289
 290 static void decr_ref_cnt_ip(struct odhcpd_ref_ip **ptr, struct interface *iface)
 291 {
 292         struct odhcpd_ref_ip *ip = *ptr;
 293
 294         if (--ip->ref_cnt == 0) {
 295                 netlink_setup_addr(&ip->addr, iface->ifindex, false, false);
 296
 297                 list_del(&ip->head);
 298                 free(ip);
 299         }
 300
 301         *ptr = NULL;
 302 }
 303
 304 static bool addr_is_fr_ip(struct interface *iface, struct in_addr *addr)
 305 {
 306         struct odhcpd_ref_ip *p;
 307
 308         list_for_each_entry(p, &iface->dhcpv4_fr_ips, head) {
 309                 if (addr->s_addr == p->addr.addr.in.s_addr)
 310                         return true;
 311         }
 312
 313         return false;
 314 }
 315
 316 static bool leases_require_fr(struct interface *iface, struct odhcpd_ipaddr *addr,
 317                                 uint32_t mask)
 318 {
 319         struct dhcp_assignment *a = NULL;
 320         struct odhcpd_ref_ip *fr_ip = NULL;
 321
 322         list_for_each_entry(a, &iface->dhcpv4_assignments, head) {
 323                 if ((a->accept_fr_nonce || iface->dhcpv4_forcereconf) &&
 324                     !a->fr_ip &&
 325                     ((a->addr & mask) == (addr->addr.in.s_addr & mask))) {
 326                         if (!fr_ip) {
 327                                 fr_ip = calloc(1, sizeof(*fr_ip));
 328                                 if (!fr_ip)
 329                                         break;
 330
 331                                 list_add(&fr_ip->head, &iface->dhcpv4_fr_ips);
 332                                 fr_ip->addr = *addr;
 333                         }
 334                         inc_ref_cnt_ip(&a->fr_ip, fr_ip);
 335                 }
 336         }
 337
 338         return fr_ip ? true : false;
 339 }
 340
 341 static void valid_until_cb(struct uloop_timeout *event)
 342 {
 343         struct interface *iface;
 344         time_t now = odhcpd_time();
 345
 346         avl_for_each_element(&interfaces, iface, avl) {
 347                 struct dhcp_assignment *a, *n;
 348
 349                 if (iface->dhcpv4 != MODE_SERVER)
 350                         continue;
 351
 352                 list_for_each_entry_safe(a, n, &iface->dhcpv4_assignments, head) {
 353                         if (!INFINITE_VALID(a->valid_until) && a->valid_until < now)
 354                                 free_assignment(a);
 355                 }
 356         }
 357         uloop_timeout_set(event, 1000);
 358 }
 359
 360 static void handle_addrlist_change(struct interface *iface)
 361 {
 362         struct odhcpd_ipaddr ip;
 363         struct odhcpd_ref_ip *a;
 364         struct dhcp_assignment *c;
 365         uint32_t mask = iface->dhcpv4_mask.s_addr;
 366
 367         memset(&ip, 0, sizeof(ip));
 368         ip.addr.in = iface->dhcpv4_local;
 369         ip.prefix = odhcpd_netmask2bitlen(false, &iface->dhcpv4_mask);
 370         ip.broadcast = iface->dhcpv4_bcast;
 371
 372         setup_dhcpv4_addresses(iface);
 373
 374         if ((ip.addr.in.s_addr & mask) ==
 375             (iface->dhcpv4_local.s_addr & iface->dhcpv4_mask.s_addr))
 376                 return;
 377
 378         if (ip.addr.in.s_addr && !leases_require_fr(iface, &ip, mask))
 379                 return;
 380
 381         if (iface->dhcpv4_local.s_addr == INADDR_ANY || list_empty(&iface->dhcpv4_fr_ips))
 382                 return;
 383
 384         a = list_first_entry(&iface->dhcpv4_fr_ips, struct odhcpd_ref_ip, head);
 385
 386         if (netlink_setup_addr(&a->addr, iface->ifindex, false, true)) {
 387                 syslog(LOG_WARNING, "Failed to add ip address on %s", iface->name);
 388                 return;
 389         }
 390
 391         list_for_each_entry(c, &iface->dhcpv4_assignments, head) {
 392                 if ((c->flags & OAF_BOUND) && c->fr_ip && !c->fr_cnt) {
 393                         if (c->accept_fr_nonce || iface->dhcpv4_forcereconf)
 394                                 dhcpv4_fr_rand_delay(c);
 395                         else
 396                                 dhcpv4_fr_stop(c);
 397                 }
 398         }
 399 }
 400
 401 static char *dhcpv4_msg_to_string(uint8_t reqmsg)
 402 {
 403         switch (reqmsg) {
 404         case (DHCPV4_MSG_DISCOVER):
 405                 return "DHCPV4_MSG_DISCOVER";
 406         case (DHCPV4_MSG_OFFER):
 407                 return "DHCPV4_MSG_OFFER";
 408         case (DHCPV4_MSG_REQUEST):
 409                 return "DHCPV4_MSG_REQUEST";
 410         case (DHCPV4_MSG_DECLINE):
 411                 return "DHCPV4_MSG_DECLINE";
 412         case (DHCPV4_MSG_ACK):
 413                 return "DHCPV4_MSG_ACK";
 414         case (DHCPV4_MSG_NAK):
 415                 return "DHCPV4_MSG_NAK";
 416         case (DHCPV4_MSG_RELEASE):
 417                 return "DHCPV4_MSG_RELEASE";
 418         case (DHCPV4_MSG_INFORM):
 419                 return "DHCPV4_MSG_INFORM";
 420         case (DHCPV4_MSG_FORCERENEW):
 421                 return "DHCPV4_MSG_FORCERENEW";
 422         default:
 423                 return "UNKNOWN";
 424         }
 425 }
 426
 427 static void dhcpv4_free_assignment(struct dhcp_assignment *a)
 428 {
 429         if (a->fr_ip)
 430                 dhcpv4_fr_stop(a);
 431 }
 432
 433 static void dhcpv4_put(struct dhcpv4_message *msg, uint8_t **cookie,
 434                 uint8_t type, uint8_t len, const void *data)
 435 {
 436         uint8_t *c = *cookie;
 437         uint8_t *end = (uint8_t *)msg + sizeof(*msg);
 438         bool tag_only = type == DHCPV4_OPT_PAD || type == DHCPV4_OPT_END;
 439         int total_len = tag_only ? 1 : 2 + len;
 440
 441         if (*cookie + total_len > end)
 442                 return;
 443
 444         *cookie += total_len;
 445         *c++ = type;
 446
 447         if (tag_only)
 448                 return;
 449
 450         *c++ = len;
 451         memcpy(c, data, len);
 452 }
 453
 454 static void dhcpv4_fr_send(struct dhcp_assignment *a)
 455 {
 456         struct dhcpv4_message fr_msg = {
 457                 .op = DHCPV4_BOOTREPLY,
 458                 .htype = 1,
 459                 .hlen = 6,
 460                 .hops = 0,
 461                 .secs = 0,
 462                 .flags = 0,
 463                 .ciaddr = {INADDR_ANY},
 464                 .yiaddr = {INADDR_ANY},
 465                 .siaddr = {INADDR_ANY},
 466                 .giaddr = {INADDR_ANY},
 467                 .chaddr = {0},
 468                 .sname = {0},
 469                 .file = {0},
 470         };
 471         struct dhcpv4_auth_forcerenew *auth_o, auth = {
 472                 .protocol = 3,
 473                 .algorithm = 1,
 474                 .rdm = 0,
 475                 .replay = {htonl(time(NULL)), htonl(++serial)},
 476                 .type = 2,
 477                 .key = {0},
 478         };
 479         struct interface *iface = a->iface;
 480
 481         odhcpd_urandom(&fr_msg.xid, sizeof(fr_msg.xid));
 482         memcpy(fr_msg.chaddr, a->hwaddr, fr_msg.hlen);
 483
 484         fr_msg.options[0] = 0x63;
 485         fr_msg.options[1] = 0x82;
 486         fr_msg.options[2] = 0x53;
 487         fr_msg.options[3] = 0x63;
 488
 489         uint8_t *cookie = &fr_msg.options[4];
 490         uint8_t msg = DHCPV4_MSG_FORCERENEW;
 491
 492         dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
 493         if (a->accept_fr_nonce) {
 494                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
 495                 auth_o = (struct dhcpv4_auth_forcerenew *)(cookie - sizeof(auth));
 496                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
 497
 498                 md5_ctx_t md5;
 499                 uint8_t secretbytes[64];
 500                 memset(secretbytes, 0, sizeof(secretbytes));
 501                 memcpy(secretbytes, a->key, sizeof(a->key));
 502
 503                 for (size_t i = 0; i < sizeof(secretbytes); ++i)
 504                         secretbytes[i] ^= 0x36;
 505
 506                 md5_begin(&md5);
 507                 md5_hash(secretbytes, sizeof(secretbytes), &md5);
 508                 md5_hash(&fr_msg, sizeof(fr_msg), &md5);
 509                 md5_end(auth_o->key, &md5);
 510
 511                 for (size_t i = 0; i < sizeof(secretbytes); ++i) {
 512                         secretbytes[i] ^= 0x36;
 513                         secretbytes[i] ^= 0x5c;
 514                 }
 515
 516                 md5_begin(&md5);
 517                 md5_hash(secretbytes, sizeof(secretbytes), &md5);
 518                 md5_hash(auth_o->key, sizeof(auth_o->key), &md5);
 519                 md5_end(auth_o->key, &md5);
 520         } else {
 521                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_SERVERID, 4,
 522                                 &a->fr_ip->addr.addr.in.s_addr);
 523                 dhcpv4_put(&fr_msg, &cookie, DHCPV4_OPT_END, 0, NULL);
 524         }
 525
 526         struct sockaddr_in dest;
 527         memset(&dest, 0, sizeof(dest));
 528         dest.sin_family = AF_INET;
 529         dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 530         dest.sin_addr.s_addr = a->addr;
 531
 532         if (sendto(iface->dhcpv4_event.uloop.fd, &fr_msg, PACKET_SIZE(&fr_msg, cookie),
 533                         MSG_DONTWAIT, (struct sockaddr*)&dest, sizeof(dest)) < 0)
 534                 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m", dhcpv4_msg_to_string(msg),
 535                         odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
 536         else
 537                 syslog(LOG_DEBUG, "Sent %s to %s - %s", dhcpv4_msg_to_string(msg),
 538                         odhcpd_print_mac(a->hwaddr, sizeof(a->hwaddr)), inet_ntoa(dest.sin_addr));
 539 }
 540
 541 static void dhcpv4_fr_timer(struct uloop_timeout *event)
 542 {
 543         struct dhcp_assignment *a = container_of(event, struct dhcp_assignment, fr_timer);
 544
 545         if (a->fr_cnt > 0 && a->fr_cnt < 8) {
 546                 dhcpv4_fr_send(a);
 547                 uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
 548                 a->fr_cnt++;
 549         } else
 550                 dhcpv4_fr_stop(a);
 551 }
 552
 553 static void dhcpv4_fr_start(struct dhcp_assignment *a)
 554 {
 555         uloop_timeout_set(&a->fr_timer, 1000 << a->fr_cnt);
 556         a->fr_timer.cb = dhcpv4_fr_timer;
 557         a->fr_cnt++;
 558
 559         dhcpv4_fr_send(a);
 560 }
 561
 562 static void dhcpv4_fr_delay_timer(struct uloop_timeout *event)
 563 {
 564         struct dhcp_assignment *a = container_of(event, struct dhcp_assignment, fr_timer);
 565         struct interface *iface = a->iface;
 566
 567         (iface->dhcpv4_event.uloop.fd == -1 ? dhcpv4_fr_rand_delay(a) : dhcpv4_fr_start(a));
 568 }
 569
 570 static void dhcpv4_fr_rand_delay(struct dhcp_assignment *a)
 571 {
 572 #define MIN_DELAY   500
 573 #define MAX_FUZZ    500
 574         int msecs;
 575
 576         odhcpd_urandom(&msecs, sizeof(msecs));
 577
 578         msecs = labs(msecs)%MAX_FUZZ + MIN_DELAY;
 579
 580         uloop_timeout_set(&a->fr_timer, msecs);
 581         a->fr_timer.cb = dhcpv4_fr_delay_timer;
 582 }
 583
 584 static void dhcpv4_fr_stop(struct dhcp_assignment *a)
 585 {
 586         uloop_timeout_cancel(&a->fr_timer);
 587         decr_ref_cnt_ip(&a->fr_ip, a->iface);
 588         a->fr_cnt = 0;
 589         a->fr_timer.cb = NULL;
 590 }
 591
 592 static int dhcpv4_send_reply(const void *buf, size_t len,
 593                              const struct sockaddr *dest, socklen_t dest_len,
 594                              void *opaque)
 595 {
 596         int *sock = opaque;
 597
 598         return sendto(*sock, buf, len, MSG_DONTWAIT, dest, dest_len);
 599 }
 600
 601 /* Handler for DHCPv4 messages */
 602 static void handle_dhcpv4(void *addr, void *data, size_t len,
 603                 struct interface *iface, _unused void *dest_addr)
 604 {
 605         int sock = iface->dhcpv4_event.uloop.fd;
 606
 607         dhcpv4_handle_msg(addr, data, len, iface, dest_addr, dhcpv4_send_reply, &sock);
 608 }
 609
 610 void dhcpv4_handle_msg(void *addr, void *data, size_t len,
 611                 struct interface *iface, _unused void *dest_addr,
 612                 send_reply_cb_t send_reply, void *opaque)
 613 {
 614         struct dhcpv4_message *req = data;
 615
 616         if (iface->dhcpv4 == MODE_DISABLED)
 617                 return;
 618
 619         if (len < offsetof(struct dhcpv4_message, options) + 4 ||
 620                         req->op != DHCPV4_BOOTREQUEST || req->hlen != 6)
 621                 return;
 622
 623         syslog(LOG_DEBUG, "Got DHCPv4 request on %s", iface->name);
 624
 625         if (!iface->dhcpv4_start_ip.s_addr && !iface->dhcpv4_end_ip.s_addr) {
 626                 syslog(LOG_WARNING, "No DHCP range available on %s", iface->name);
 627                 return;
 628         }
 629
 630         int sock = iface->dhcpv4_event.uloop.fd;
 631
 632         struct dhcpv4_message reply = {
 633                 .op = DHCPV4_BOOTREPLY,
 634                 .htype = req->htype,
 635                 .hlen = req->hlen,
 636                 .hops = 0,
 637                 .xid = req->xid,
 638                 .secs = 0,
 639                 .flags = req->flags,
 640                 .ciaddr = {INADDR_ANY},
 641                 .giaddr = req->giaddr,
 642                 .siaddr = iface->dhcpv4_local,
 643         };
 644         memcpy(reply.chaddr, req->chaddr, sizeof(reply.chaddr));
 645
 646         reply.options[0] = 0x63;
 647         reply.options[1] = 0x82;
 648         reply.options[2] = 0x53;
 649         reply.options[3] = 0x63;
 650
 651         uint8_t *cookie = &reply.options[4];
 652         uint8_t reqmsg = DHCPV4_MSG_REQUEST;
 653         uint8_t msg = DHCPV4_MSG_ACK;
 654
 655         uint32_t reqaddr = INADDR_ANY;
 656         uint32_t leasetime = 0;
 657         size_t hostname_len = 0;
 658         size_t reqopts_len = 0;
 659         char hostname[256];
 660         char reqopts[256];
 661         bool accept_fr_nonce = false;
 662         bool incl_fr_opt = false;
 663
 664         uint8_t *start = &req->options[4];
 665         uint8_t *end = ((uint8_t*)data) + len;
 666         struct dhcpv4_option *opt;
 667         dhcpv4_for_each_option(start, end, opt) {
 668                 if (opt->type == DHCPV4_OPT_MESSAGE && opt->len == 1)
 669                         reqmsg = opt->data[0];
 670                 else if (opt->type == DHCPV4_OPT_REQOPTS && opt->len > 0) {
 671                         reqopts_len = opt->len;
 672                         memcpy(reqopts, opt->data, reqopts_len);
 673                         reqopts[reqopts_len] = 0;
 674                 } else if (opt->type == DHCPV4_OPT_HOSTNAME && opt->len > 0) {
 675                         hostname_len = opt->len;
 676                         memcpy(hostname, opt->data, hostname_len);
 677                         hostname[hostname_len] = 0;
 678                 } else if (opt->type == DHCPV4_OPT_IPADDRESS && opt->len == 4)
 679                         memcpy(&reqaddr, opt->data, 4);
 680                 else if (opt->type == DHCPV4_OPT_SERVERID && opt->len == 4) {
 681                         if (memcmp(opt->data, &iface->dhcpv4_local, 4))
 682                                 return;
 683                 } else if (iface->filter_class && opt->type == DHCPV4_OPT_USER_CLASS) {
 684                         uint8_t *c = opt->data, *cend = &opt->data[opt->len];
 685                         for (; c < cend && &c[*c] < cend; c = &c[1 + *c]) {
 686                                 size_t elen = strlen(iface->filter_class);
 687                                 if (*c == elen && !memcmp(&c[1], iface->filter_class, elen))
 688                                         return; // Ignore from homenet
 689                         }
 690                 } else if (opt->type == DHCPV4_OPT_LEASETIME && opt->len == 4)
 691                         memcpy(&leasetime, opt->data, 4);
 692                 else if (opt->type == DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE && opt->len > 0) {
 693                         for (uint8_t i = 0; i < opt->len; i++) {
 694                                 if (opt->data[i] == 1) {
 695                                         accept_fr_nonce = true;
 696                                         break;
 697                                 }
 698                         }
 699
 700                 }
 701         }
 702
 703         if (reqmsg != DHCPV4_MSG_DISCOVER && reqmsg != DHCPV4_MSG_REQUEST &&
 704             reqmsg != DHCPV4_MSG_INFORM && reqmsg != DHCPV4_MSG_DECLINE &&
 705             reqmsg != DHCPV4_MSG_RELEASE)
 706                 return;
 707
 708         struct dhcp_assignment *a = NULL;
 709         uint32_t serverid = iface->dhcpv4_local.s_addr;
 710         uint32_t fr_serverid = INADDR_ANY;
 711
 712         if (reqmsg != DHCPV4_MSG_INFORM)
 713                 a = dhcpv4_lease(iface, reqmsg, req->chaddr, reqaddr,
 714                                  &leasetime, hostname, hostname_len,
 715                                  accept_fr_nonce, &incl_fr_opt, &fr_serverid,
 716                                  reqopts, reqopts_len);
 717
 718         if (!a) {
 719                 if (reqmsg == DHCPV4_MSG_REQUEST)
 720                         msg = DHCPV4_MSG_NAK;
 721                 else if (reqmsg == DHCPV4_MSG_DISCOVER)
 722                         return;
 723         } else if (reqmsg == DHCPV4_MSG_DISCOVER)
 724                 msg = DHCPV4_MSG_OFFER;
 725         else if (reqmsg == DHCPV4_MSG_REQUEST &&
 726                         ((reqaddr && reqaddr != a->addr) ||
 727                          (req->ciaddr.s_addr && req->ciaddr.s_addr != a->addr))) {
 728                 msg = DHCPV4_MSG_NAK;
 729                 /*
 730                  * DHCP client requested an IP which we can't offer to him. Probably the
 731                  * client changed the network or the network has been changed. The reply
 732                  * type is set to DHCPV4_MSG_NAK, because the client should not use that IP.
 733                  *
 734                  * For modern devices we build an answer that includes a valid IP, like
 735                  * a DHCPV4_MSG_ACK. The client will use that IP and doesn't need to
 736                  * perform additional DHCP round trips.
 737                  *
 738                  */
 739
 740                 /*
 741                  *
 742                  * Buggy clients do serverid checking in nack messages; therefore set the
 743                  * serverid in nack messages triggered by a previous force renew equal to
 744                  * the server id in use at that time by the server
 745                  *
 746                  */
 747                 if (fr_serverid)
 748                         serverid = fr_serverid;
 749
 750                 if (req->ciaddr.s_addr &&
 751                                 ((iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr) !=
 752                                  (req->ciaddr.s_addr & iface->dhcpv4_mask.s_addr)))
 753                         req->ciaddr.s_addr = INADDR_ANY;
 754         }
 755
 756         syslog(LOG_INFO, "Received %s from %s on %s", dhcpv4_msg_to_string(reqmsg),
 757                         odhcpd_print_mac(req->chaddr, req->hlen), iface->name);
 758
 759 #ifdef WITH_UBUS
 760         if (reqmsg == DHCPV4_MSG_RELEASE)
 761                 ubus_bcast_dhcp_event("dhcp.release", req->chaddr, req->hlen,
 762                                         &req->ciaddr, a ? a->hostname : NULL, iface->ifname);
 763 #endif
 764         if (reqmsg == DHCPV4_MSG_DECLINE || reqmsg == DHCPV4_MSG_RELEASE)
 765                 return;
 766
 767         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MESSAGE, 1, &msg);
 768         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SERVERID, 4, &serverid);
 769
 770         if (a) {
 771                 uint32_t val;
 772
 773                 reply.yiaddr.s_addr = a->addr;
 774
 775                 val = htonl(leasetime);
 776                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_LEASETIME, 4, &val);
 777
 778                 if (leasetime != UINT32_MAX) {
 779                         val = htonl(500 * leasetime / 1000);
 780                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_RENEW, 4, &val);
 781
 782                         val = htonl(875 * leasetime / 1000);
 783                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_REBIND, 4, &val);
 784                 }
 785
 786                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NETMASK, 4,
 787                                 &iface->dhcpv4_mask.s_addr);
 788
 789                 if (a->hostname)
 790                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_HOSTNAME,
 791                                         strlen(a->hostname), a->hostname);
 792
 793                 if (iface->dhcpv4_bcast.s_addr != INADDR_ANY)
 794                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_BROADCAST, 4, &iface->dhcpv4_bcast);
 795
 796                 if (incl_fr_opt) {
 797                         if (reqmsg == DHCPV4_MSG_REQUEST) {
 798                                 struct dhcpv4_auth_forcerenew auth = {
 799                                         .protocol = 3,
 800                                         .algorithm = 1,
 801                                         .rdm = 0,
 802                                         .replay = {htonl(time(NULL)), htonl(++serial)},
 803                                         .type = 1,
 804                                         .key = {0},
 805                                 };
 806
 807                                 memcpy(auth.key, a->key, sizeof(auth.key));
 808                                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_AUTHENTICATION, sizeof(auth), &auth);
 809                         } else {
 810                                 uint8_t one = 1;
 811                                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_FORCERENEW_NONCE_CAPABLE,
 812                                         sizeof(one), &one);
 813                         }
 814                 }
 815         }
 816
 817         struct ifreq ifr;
 818
 819         memset(&ifr, 0, sizeof(ifr));
 820         strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name) - 1);
 821
 822         if (!ioctl(sock, SIOCGIFMTU, &ifr)) {
 823                 uint16_t mtu = htons(ifr.ifr_mtu);
 824                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_MTU, 2, &mtu);
 825         }
 826
 827         if (iface->search && iface->search_len <= 255)
 828                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
 829                                 iface->search_len, iface->search);
 830         else if (!res_init() && _res.dnsrch[0] && _res.dnsrch[0][0]) {
 831                 uint8_t search_buf[256];
 832                 int len = dn_comp(_res.dnsrch[0], search_buf,
 833                                                 sizeof(search_buf), NULL, NULL);
 834                 if (len > 0)
 835                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_SEARCH_DOMAIN,
 836                                         len, search_buf);
 837         }
 838
 839         if (iface->dhcpv4_router_cnt == 0)
 840                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER, 4, &iface->dhcpv4_local);
 841         else
 842                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_ROUTER,
 843                                 4 * iface->dhcpv4_router_cnt, iface->dhcpv4_router);
 844
 845
 846         if (iface->dhcpv4_dns_cnt == 0) {
 847                 if (iface->dns_service)
 848                         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER, 4, &iface->dhcpv4_local);
 849         } else
 850                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_DNSSERVER,
 851                                 4 * iface->dhcpv4_dns_cnt, iface->dhcpv4_dns);
 852
 853         if (a && a->reqopts && iface->dhcpv4_ntp_cnt != 0) {
 854                 for(size_t opts = 0; a->reqopts[opts]; opts++) {
 855                         if (a->reqopts[opts] == DHCPV4_OPT_NTPSERVER) {
 856                                 dhcpv4_put(&reply, &cookie, DHCPV4_OPT_NTPSERVER,
 857                                                 4 * iface->dhcpv4_ntp_cnt, iface->dhcpv4_ntp);
 858                         }
 859                 }
 860         }
 861
 862         dhcpv4_put(&reply, &cookie, DHCPV4_OPT_END, 0, NULL);
 863
 864         struct sockaddr_in dest = *((struct sockaddr_in*)addr);
 865         if (req->giaddr.s_addr) {
 866                 /*
 867                  * relay agent is configured, send reply to the agent
 868                  */
 869                 dest.sin_addr = req->giaddr;
 870                 dest.sin_port = htons(DHCPV4_SERVER_PORT);
 871         } else if (req->ciaddr.s_addr && req->ciaddr.s_addr != dest.sin_addr.s_addr) {
 872                 /*
 873                  * client has existing configuration (ciaddr is set) AND this address is
 874                  * not the address it used for the dhcp message
 875                  */
 876                 dest.sin_addr = req->ciaddr;
 877                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 878         } else if ((ntohs(req->flags) & DHCPV4_FLAG_BROADCAST) ||
 879                         req->hlen != reply.hlen || !reply.yiaddr.s_addr) {
 880                 /*
 881                  * client requests a broadcast reply OR we can't offer an IP
 882                  */
 883                 dest.sin_addr.s_addr = INADDR_BROADCAST;
 884                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 885         } else if (!req->ciaddr.s_addr && msg == DHCPV4_MSG_NAK) {
 886                 /*
 887                  * client has no previous configuration -> no IP, so we need to reply
 888                  * with a broadcast packet
 889                  */
 890                 dest.sin_addr.s_addr = INADDR_BROADCAST;
 891                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 892         } else {
 893                 struct arpreq arp = {.arp_flags = ATF_COM};
 894
 895                 /*
 896                  * send reply to the newly (in this process) allocated IP
 897                  */
 898                 dest.sin_addr = reply.yiaddr;
 899                 dest.sin_port = htons(DHCPV4_CLIENT_PORT);
 900
 901                 if (!(iface->ifflags & IFF_NOARP)) {
 902                         memcpy(arp.arp_ha.sa_data, req->chaddr, 6);
 903                         memcpy(&arp.arp_pa, &dest, sizeof(arp.arp_pa));
 904                         memcpy(arp.arp_dev, iface->ifname, sizeof(arp.arp_dev));
 905
 906                         if (ioctl(sock, SIOCSARP, &arp) < 0)
 907                                 syslog(LOG_ERR, "ioctl(SIOCSARP): %m");
 908                 }
 909         }
 910
 911         if (send_reply(&reply, PACKET_SIZE(&reply, cookie),
 912                        (struct sockaddr*)&dest, sizeof(dest), opaque) < 0)
 913                 syslog(LOG_ERR, "Failed to send %s to %s - %s: %m",
 914                         dhcpv4_msg_to_string(msg),
 915                         dest.sin_addr.s_addr == INADDR_BROADCAST ?
 916                         "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
 917                         inet_ntoa(dest.sin_addr));
 918         else
 919                 syslog(LOG_DEBUG, "Sent %s to %s - %s",
 920                         dhcpv4_msg_to_string(msg),
 921                         dest.sin_addr.s_addr == INADDR_BROADCAST ?
 922                         "ff:ff:ff:ff:ff:ff": odhcpd_print_mac(req->chaddr, req->hlen),
 923                         inet_ntoa(dest.sin_addr));
 924
 925
 926 #ifdef WITH_UBUS
 927         if (msg == DHCPV4_MSG_ACK)
 928                 ubus_bcast_dhcp_event("dhcp.ack", req->chaddr, req->hlen, &reply.yiaddr,
 929                                         a ? a->hostname : NULL, iface->ifname);
 930 #endif
 931 }
 932
 933 static bool dhcpv4_insert_assignment(struct list_head *list, struct dhcp_assignment *a,
 934                                      uint32_t addr)
 935 {
 936         uint32_t h_addr = ntohl(addr);
 937         struct dhcp_assignment *c;
 938
 939         list_for_each_entry(c, list, head) {
 940                 uint32_t c_addr = ntohl(c->addr);
 941
 942                 if (c_addr == h_addr)
 943                         return false;
 944
 945                 if (c_addr > h_addr)
 946                         break;
 947         }
 948
 949         /* Insert new node before c (might match list head) */
 950         a->addr = addr;
 951         list_add_tail(&a->head, &c->head);
 952
 953         return true;
 954 }
 955
 956 static char* ip4toa(uint32_t addr)
 957 {
 958         static char buf[16];
 959
 960         snprintf(buf, sizeof(buf), "%u.%u.%u.%u",
 961                 ((uint8_t *)&addr)[0], ((uint8_t *)&addr)[1],
 962                 ((uint8_t *)&addr)[2], ((uint8_t *)&addr)[3]);
 963
 964         return buf;
 965 }
 966
 967 static bool dhcpv4_assign(struct interface *iface, struct dhcp_assignment *a,
 968                           uint32_t raddr)
 969 {
 970         uint32_t start = ntohl(iface->dhcpv4_start_ip.s_addr);
 971         uint32_t end = ntohl(iface->dhcpv4_end_ip.s_addr);
 972         uint32_t count = end - start + 1;
 973         uint32_t seed = 0;
 974         bool assigned;
 975
 976         /* Preconfigured IP address by static lease */
 977         if (a->addr) {
 978                 assigned = dhcpv4_insert_assignment(&iface->dhcpv4_assignments,
 979                                                     a, a->addr);
 980
 981                 if (assigned)
 982                         syslog(LOG_DEBUG, "Assigning static IP: %s", ip4toa(a->addr));
 983
 984                 return assigned;
 985         }
 986
 987         /* try to assign the IP the client asked for */
 988         if (start <= ntohl(raddr) && ntohl(raddr) <= end &&
 989             !config_find_lease_by_ipaddr(raddr)) {
 990                 assigned = dhcpv4_insert_assignment(&iface->dhcpv4_assignments,
 991                                                     a, raddr);
 992
 993                 if (assigned) {
 994                         syslog(LOG_DEBUG, "Assigning the IP the client asked for: %s",
 995                                ip4toa(a->addr));
 996
 997                         return true;
 998                 }
 999         }
1000
1001         /* Seed RNG with checksum of hwaddress */
1002         for (size_t i = 0; i < sizeof(a->hwaddr); ++i) {
1003                 /* Knuth's multiplicative method */
1004                 uint8_t o = a->hwaddr[i];
1005                 seed += (o*2654435761) % UINT32_MAX;
1006         }
1007
1008         srand(seed);
1009
1010         for (uint32_t i = 0, try = (((uint32_t)rand()) % count) + start; i < count;
1011              ++i, try = (((try - start) + 1) % count) + start) {
1012                 uint32_t n_try = htonl(try);
1013
1014                 if (config_find_lease_by_ipaddr(n_try))
1015                         continue;
1016
1017                 assigned = dhcpv4_insert_assignment(&iface->dhcpv4_assignments,
1018                                                     a, n_try);
1019
1020                 if (assigned) {
1021                         syslog(LOG_DEBUG, "Assigning mapped IP: %s (try %u of %u)",
1022                                ip4toa(a->addr), i + 1, count);
1023
1024                         return true;
1025                 }
1026         }
1027
1028         syslog(LOG_NOTICE, "Can't assign any IP address -> address space is full");
1029
1030         return false;
1031 }
1032
1033
1034 static struct dhcp_assignment*
1035 dhcpv4_lease(struct interface *iface, enum dhcpv4_msg msg, const uint8_t *mac,
1036              const uint32_t reqaddr, uint32_t *leasetime, const char *hostname,
1037              const size_t hostname_len, const bool accept_fr_nonce, bool *incl_fr_opt,
1038              uint32_t *fr_serverid, const char* reqopts, const size_t reqopts_len)
1039 {
1040         struct dhcp_assignment *a = find_assignment_by_hwaddr(iface, mac);
1041         struct lease *l = config_find_lease_by_mac(mac);
1042         time_t now = odhcpd_time();
1043
1044         if (l && a && a->lease != l) {
1045                 free_assignment(a);
1046                 a = NULL;
1047         }
1048
1049         if (a && (a->flags & OAF_BOUND) && a->fr_ip) {
1050                 *fr_serverid = a->fr_ip->addr.addr.in.s_addr;
1051                 dhcpv4_fr_stop(a);
1052         }
1053
1054         if (msg == DHCPV4_MSG_DISCOVER || msg == DHCPV4_MSG_REQUEST) {
1055                 bool assigned = !!a;
1056
1057                 if (!a) {
1058                         if (!iface->no_dynamic_dhcp || l) {
1059                                 /* Create new binding */
1060                                 a = alloc_assignment(0);
1061                                 if (!a) {
1062                                         syslog(LOG_WARNING, "Failed to alloc assignment on interface %s",
1063                                                             iface->ifname);
1064                                         return NULL;
1065                                 }
1066                                 memcpy(a->hwaddr, mac, sizeof(a->hwaddr));
1067                                 /* Set valid time to 0 for static lease indicating */
1068                                 /* infinite lifetime otherwise current time        */
1069                                 a->valid_until = l ? 0 : now;
1070                                 a->dhcp_free_cb = dhcpv4_free_assignment;
1071                                 a->iface = iface;
1072                                 a->flags = OAF_DHCPV4;
1073                                 a->addr = l ? l->ipaddr : INADDR_ANY;
1074
1075                                 assigned = dhcpv4_assign(iface, a, reqaddr);
1076
1077                                 if (l) {
1078                                         a->flags |= OAF_STATIC;
1079
1080                                         if (l->hostname)
1081                                                 a->hostname = strdup(l->hostname);
1082
1083                                         if (l->leasetime)
1084                                                 a->leasetime = l->leasetime;
1085
1086                                         list_add(&a->lease_list, &l->assignments);
1087                                         a->lease = l;
1088                                 }
1089                         }
1090                 } else if (((a->addr & iface->dhcpv4_mask.s_addr) !=
1091                             (iface->dhcpv4_start_ip.s_addr & iface->dhcpv4_mask.s_addr)) &&
1092                             !(a->flags & OAF_STATIC)) {
1093                         list_del_init(&a->head);
1094                         a->addr = INADDR_ANY;
1095
1096                         assigned = dhcpv4_assign(iface, a, reqaddr);
1097                 }
1098
1099                 if (assigned) {
1100                         uint32_t my_leasetime;
1101
1102                         if (a->leasetime)
1103                                 my_leasetime = a->leasetime;
1104                         else
1105                                 my_leasetime = iface->dhcp_leasetime;
1106
1107                         if ((*leasetime == 0) || (my_leasetime < *leasetime))
1108                                 *leasetime = my_leasetime;
1109
1110                         if (msg == DHCPV4_MSG_DISCOVER) {
1111                                 a->flags &= ~OAF_BOUND;
1112
1113                                 *incl_fr_opt = accept_fr_nonce;
1114                                 a->valid_until = now;
1115                         } else {
1116                                 if ((!(a->flags & OAF_STATIC) || !a->hostname) && hostname_len > 0) {
1117                                         a->hostname = realloc(a->hostname, hostname_len + 1);
1118                                         if (a->hostname) {
1119                                                 memcpy(a->hostname, hostname, hostname_len);
1120                                                 a->hostname[hostname_len] = 0;
1121
1122                                                 if (odhcpd_valid_hostname(a->hostname))
1123                                                         a->flags &= ~OAF_BROKEN_HOSTNAME;
1124                                                 else
1125                                                         a->flags |= OAF_BROKEN_HOSTNAME;
1126                                         }
1127                                 }
1128
1129                                 if (reqopts_len > 0) {
1130                                         a->reqopts = realloc(a->reqopts, reqopts_len + 1);
1131                                         if (a->reqopts) {
1132                                                 memcpy(a->reqopts, reqopts, reqopts_len);
1133                                                 a->reqopts[reqopts_len] = 0;
1134                                         }
1135                                 }
1136
1137                                 if (!(a->flags & OAF_BOUND)) {
1138                                         a->accept_fr_nonce = accept_fr_nonce;
1139                                         *incl_fr_opt = accept_fr_nonce;
1140                                         odhcpd_urandom(a->key, sizeof(a->key));
1141                                         a->flags |= OAF_BOUND;
1142                                 } else
1143                                         *incl_fr_opt = false;
1144
1145                                 a->valid_until = ((*leasetime == UINT32_MAX) ? 0 : (time_t)(now + *leasetime));
1146                         }
1147                 } else if (!assigned && a) {
1148                         /* Cleanup failed assignment */
1149                         free_assignment(a);
1150                         a = NULL;
1151                 }
1152
1153         } else if (msg == DHCPV4_MSG_RELEASE && a) {
1154                 a->flags &= ~OAF_BOUND;
1155                 a->valid_until = now - 1;
1156
1157         } else if (msg == DHCPV4_MSG_DECLINE && a) {
1158                 a->flags &= ~OAF_BOUND;
1159
1160                 if (!(a->flags & OAF_STATIC) || a->lease->ipaddr != a->addr) {
1161                         memset(a->hwaddr, 0, sizeof(a->hwaddr));
1162                         a->valid_until = now + 3600; /* Block address for 1h */
1163                 } else
1164                         a->valid_until = now - 1;
1165         }
1166
1167         dhcpv6_ia_write_statefile();
1168
1169         return a;
1170 }