src/odhcpd.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 <errno.h>
  17 #include <fcntl.h>
  18 #include <stdio.h>
  19 #include <resolv.h>
  20 #include <getopt.h>
  21 #include <stddef.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <unistd.h>
  25 #include <signal.h>
  26 #include <stdbool.h>
  27 #include <syslog.h>
  28 #include <alloca.h>
  29
  30 #include <arpa/inet.h>
  31 #include <net/if.h>
  32 #include <netinet/ip6.h>
  33 #include <netpacket/packet.h>
  34 #include <linux/netlink.h>
  35 #include <linux/if_addr.h>
  36 #include <linux/neighbour.h>
  37 #include <linux/rtnetlink.h>
  38
  39 #include <sys/socket.h>
  40 #include <sys/ioctl.h>
  41 #include <sys/epoll.h>
  42 #include <sys/types.h>
  43 #include <sys/wait.h>
  44 #include <sys/syscall.h>
  45
  46 #include <netlink/msg.h>
  47 #include <netlink/socket.h>
  48 #include <netlink/attr.h>
  49 #include <libubox/uloop.h>
  50 #include "odhcpd.h"
  51
  52
  53
  54 static int ioctl_sock;
  55 static struct nl_sock *rtnl_socket = NULL;
  56 static int urandom_fd = -1;
  57
  58 static void sighandler(_unused int signal)
  59 {
  60         uloop_end();
  61 }
  62
  63 static void print_usage(const char *app)
  64 {
  65         printf(
  66         "== %s Usage ==\n\n"
  67         "  -h, --help   Print this help\n"
  68         "  -l level     Specify log level 0..7 (default %d)\n",
  69                 app, config.log_level
  70         );
  71 }
  72
  73 int main(int argc, char **argv)
  74 {
  75         openlog("odhcpd", LOG_PERROR | LOG_PID, LOG_DAEMON);
  76         int opt;
  77
  78         while ((opt = getopt(argc, argv, "hl:")) != -1) {
  79                 switch (opt) {
  80                 case 'h':
  81                         print_usage(argv[0]);
  82                         return 0;
  83                 case 'l':
  84                         config.log_level = (atoi(optarg) & LOG_PRIMASK);
  85                         fprintf(stderr, "Log level set to %d\n", config.log_level);
  86                         break;
  87                 }
  88         }
  89         setlogmask(LOG_UPTO(config.log_level));
  90         uloop_init();
  91
  92         if (getuid() != 0) {
  93                 syslog(LOG_ERR, "Must be run as root!");
  94                 return 2;
  95         }
  96
  97         ioctl_sock = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
  98
  99         if (!(rtnl_socket = odhcpd_create_nl_socket(NETLINK_ROUTE))) {
 100                 syslog(LOG_ERR, "Unable to open nl socket: %s", strerror(errno));
 101                 return 2;
 102         }
 103
 104         if ((urandom_fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC)) < 0)
 105                 return 4;
 106
 107         signal(SIGUSR1, SIG_IGN);
 108         signal(SIGINT, sighandler);
 109         signal(SIGTERM, sighandler);
 110
 111         if (init_router())
 112                 return 4;
 113
 114         if (init_dhcpv6())
 115                 return 4;
 116
 117         if (init_ndp())
 118                 return 4;
 119
 120         if (init_dhcpv4())
 121                 return 4;
 122
 123         odhcpd_run();
 124         return 0;
 125 }
 126
 127 struct nl_sock *odhcpd_create_nl_socket(int protocol)
 128 {
 129         struct nl_sock *nl_sock;
 130
 131         nl_sock = nl_socket_alloc();
 132         if (!nl_sock)
 133                 goto err;
 134
 135         if (nl_connect(nl_sock, protocol) < 0)
 136                 goto err;
 137
 138         return nl_sock;
 139
 140 err:
 141         if (nl_sock)
 142                 nl_socket_free(nl_sock);
 143
 144         return NULL;
 145 }
 146
 147
 148 // Read IPv6 MTU for interface
 149 int odhcpd_get_interface_config(const char *ifname, const char *what)
 150 {
 151         char buf[64];
 152         const char *sysctl_pattern = "/proc/sys/net/ipv6/conf/%s/%s";
 153         snprintf(buf, sizeof(buf), sysctl_pattern, ifname, what);
 154
 155         int fd = open(buf, O_RDONLY);
 156         ssize_t len = read(fd, buf, sizeof(buf) - 1);
 157         close(fd);
 158
 159         if (len < 0)
 160                 return -1;
 161
 162         buf[len] = 0;
 163         return atoi(buf);
 164 }
 165
 166
 167 // Read IPv6 MAC for interface
 168 int odhcpd_get_mac(const struct interface *iface, uint8_t mac[6])
 169 {
 170         struct ifreq ifr;
 171         memset(&ifr, 0, sizeof(ifr));
 172         strncpy(ifr.ifr_name, iface->ifname, sizeof(ifr.ifr_name));
 173         if (ioctl(ioctl_sock, SIOCGIFHWADDR, &ifr) < 0)
 174                 return -1;
 175         memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
 176         return 0;
 177 }
 178
 179
 180 // Forwards a packet on a specific interface
 181 ssize_t odhcpd_send(int socket, struct sockaddr_in6 *dest,
 182                 struct iovec *iov, size_t iov_len,
 183                 const struct interface *iface)
 184 {
 185         // Construct headers
 186         uint8_t cmsg_buf[CMSG_SPACE(sizeof(struct in6_pktinfo))] = {0};
 187         struct msghdr msg = {
 188                 .msg_name = (void *) dest,
 189                 .msg_namelen = sizeof(*dest),
 190                 .msg_iov = iov,
 191                 .msg_iovlen = iov_len,
 192                 .msg_control = cmsg_buf,
 193                 .msg_controllen = sizeof(cmsg_buf),
 194                 .msg_flags = 0
 195         };
 196
 197         // Set control data (define destination interface)
 198         struct cmsghdr *chdr = CMSG_FIRSTHDR(&msg);
 199         chdr->cmsg_level = IPPROTO_IPV6;
 200         chdr->cmsg_type = IPV6_PKTINFO;
 201         chdr->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
 202         struct in6_pktinfo *pktinfo = (struct in6_pktinfo*)CMSG_DATA(chdr);
 203         pktinfo->ipi6_ifindex = iface->ifindex;
 204
 205         // Also set scope ID if link-local
 206         if (IN6_IS_ADDR_LINKLOCAL(&dest->sin6_addr)
 207                         || IN6_IS_ADDR_MC_LINKLOCAL(&dest->sin6_addr))
 208                 dest->sin6_scope_id = iface->ifindex;
 209
 210         char ipbuf[INET6_ADDRSTRLEN];
 211         inet_ntop(AF_INET6, &dest->sin6_addr, ipbuf, sizeof(ipbuf));
 212
 213         ssize_t sent = sendmsg(socket, &msg, MSG_DONTWAIT);
 214         if (sent < 0)
 215                 syslog(LOG_NOTICE, "Failed to send to %s%%%s (%s)",
 216                                 ipbuf, iface->ifname, strerror(errno));
 217         else
 218                 syslog(LOG_DEBUG, "Sent %li bytes to %s%%%s",
 219                                 (long)sent, ipbuf, iface->ifname);
 220         return sent;
 221 }
 222
 223 struct addr_info {
 224         int ifindex;
 225         int af;
 226         struct odhcpd_ipaddr **addrs;
 227         int pending;
 228         ssize_t ret;
 229 };
 230
 231 static int cb_valid_handler(struct nl_msg *msg, void *arg)
 232 {
 233         struct addr_info *ctxt = (struct addr_info *)arg;
 234         struct odhcpd_ipaddr *addrs = *(ctxt->addrs);
 235         struct nlmsghdr *hdr = nlmsg_hdr(msg);
 236         struct ifaddrmsg *ifa;
 237         struct nlattr *nla[__IFA_MAX], *nla_addr = NULL;
 238
 239         if (hdr->nlmsg_type != RTM_NEWADDR)
 240                 return NL_SKIP;
 241
 242         ifa = NLMSG_DATA(hdr);
 243         if (ifa->ifa_scope != RT_SCOPE_UNIVERSE ||
 244                         (ctxt->af != ifa->ifa_family) ||
 245                         (ctxt->ifindex && ifa->ifa_index != (unsigned)ctxt->ifindex))
 246                 return NL_SKIP;
 247
 248         nlmsg_parse(hdr, sizeof(*ifa), nla, __IFA_MAX - 1, NULL);
 249
 250         switch (ifa->ifa_family) {
 251         case AF_INET6:
 252                 if (nla[IFA_ADDRESS])
 253                         nla_addr = nla[IFA_ADDRESS];
 254                 break;
 255
 256         case AF_INET:
 257                 if (nla[IFA_LOCAL])
 258                         nla_addr = nla[IFA_LOCAL];
 259                 break;
 260
 261         default:
 262                 break;
 263         }
 264         if (!nla_addr)
 265                 return NL_SKIP;
 266
 267         addrs = realloc(addrs, sizeof(*addrs)*(ctxt->ret + 1));
 268         if (!addrs)
 269                 return NL_SKIP;
 270
 271         memset(&addrs[ctxt->ret], 0, sizeof(addrs[ctxt->ret]));
 272         addrs[ctxt->ret].prefix = ifa->ifa_prefixlen;
 273
 274         nla_memcpy(&addrs[ctxt->ret].addr, nla_addr,
 275                         sizeof(addrs[ctxt->ret].addr));
 276
 277         if (nla[IFA_BROADCAST])
 278                 nla_memcpy(&addrs[ctxt->ret].broadcast, nla[IFA_BROADCAST],
 279                                 sizeof(addrs[ctxt->ret].broadcast));
 280
 281         if (nla[IFA_CACHEINFO]) {
 282                 struct ifa_cacheinfo *ifc = nla_data(nla[IFA_CACHEINFO]);
 283
 284                 addrs[ctxt->ret].preferred = ifc->ifa_prefered;
 285                 addrs[ctxt->ret].valid = ifc->ifa_valid;
 286         }
 287
 288         if (ifa->ifa_flags & IFA_F_DEPRECATED)
 289                 addrs[ctxt->ret].preferred = 0;
 290
 291         ctxt->ret++;
 292         *(ctxt->addrs) = addrs;
 293
 294         return NL_OK;
 295 }
 296
 297 static int cb_finish_handler(_unused struct nl_msg *msg, void *arg)
 298 {
 299         struct addr_info *ctxt = (struct addr_info *)arg;
 300
 301         ctxt->pending = 0;
 302
 303         return NL_STOP;
 304 }
 305
 306 static int cb_error_handler(_unused struct sockaddr_nl *nla, struct nlmsgerr *err,
 307                 void *arg)
 308 {
 309         struct addr_info *ctxt = (struct addr_info *)arg;
 310
 311         ctxt->pending = 0;
 312         ctxt->ret = err->error;
 313
 314         return NL_STOP;
 315 }
 316
 317 static int prefix_cmp(const void *va, const void *vb)
 318 {
 319         const struct odhcpd_ipaddr *a = va, *b = vb;
 320         int ret = 0;
 321
 322         if (a->prefix == b->prefix) {
 323                 ret = (ntohl(a->addr.in.s_addr) < ntohl(b->addr.in.s_addr)) ? 1 :
 324                         (ntohl(a->addr.in.s_addr) > ntohl(b->addr.in.s_addr)) ? -1 : 0;
 325         } else
 326                 ret = a->prefix < b->prefix ? 1 : -1;
 327
 328         return ret;
 329 }
 330
 331 // compare IPv6 prefixes
 332 static int prefix6_cmp(const void *va, const void *vb)
 333 {
 334         const struct odhcpd_ipaddr *a = va, *b = vb;
 335         uint32_t a_pref = IN6_IS_ADDR_ULA(&a->addr.in6) ? 1 : a->preferred;
 336         uint32_t b_pref = IN6_IS_ADDR_ULA(&b->addr.in6) ? 1 : b->preferred;
 337         return (a_pref < b_pref) ? 1 : (a_pref > b_pref) ? -1 : 0;
 338 }
 339
 340 // Detect an IPV6-address currently assigned to the given interface
 341 ssize_t odhcpd_get_interface_addresses(int ifindex, bool v6, struct odhcpd_ipaddr **addrs)
 342 {
 343         struct nl_msg *msg;
 344         struct ifaddrmsg ifa = {
 345                 .ifa_family = v6? AF_INET6: AF_INET,
 346                 .ifa_prefixlen = 0,
 347                 .ifa_flags = 0,
 348                 .ifa_scope = 0,
 349                 .ifa_index = ifindex, };
 350         struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
 351         struct addr_info ctxt = {
 352                 .ifindex = ifindex,
 353                 .af = v6? AF_INET6: AF_INET,
 354                 .addrs = addrs,
 355                 .ret = 0,
 356                 .pending = 1,
 357         };
 358
 359         if (!cb) {
 360                 ctxt.ret = -1;
 361                 goto out;
 362         }
 363
 364         msg = nlmsg_alloc_simple(RTM_GETADDR, NLM_F_REQUEST | NLM_F_DUMP);
 365
 366         if (!msg) {
 367                 ctxt.ret = - 1;
 368                 goto out;
 369         }
 370
 371         nlmsg_append(msg, &ifa, sizeof(ifa), 0);
 372
 373         nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_valid_handler, &ctxt);
 374         nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_finish_handler, &ctxt);
 375         nl_cb_err(cb, NL_CB_CUSTOM, cb_error_handler, &ctxt);
 376
 377         nl_send_auto_complete(rtnl_socket, msg);
 378         while (ctxt.pending > 0)
 379                 nl_recvmsgs(rtnl_socket, cb);
 380
 381         nlmsg_free(msg);
 382
 383         if (ctxt.ret <= 0)
 384                 goto out;
 385
 386         time_t now = odhcpd_time();
 387         struct odhcpd_ipaddr *addr = *addrs;
 388
 389         qsort(addr, ctxt.ret, sizeof(*addr), v6 ? prefix6_cmp : prefix_cmp);
 390
 391         for (ssize_t i = 0; i < ctxt.ret; ++i) {
 392                 if (addr[i].preferred < UINT32_MAX - now)
 393                         addr[i].preferred += now;
 394
 395                 if (addr[i].valid < UINT32_MAX - now)
 396                         addr[i].valid += now;
 397         }
 398
 399 out:
 400         nl_cb_put(cb);
 401
 402         return ctxt.ret;
 403 }
 404
 405 static int odhcpd_get_linklocal_interface_address(int ifindex, struct in6_addr *lladdr)
 406 {
 407         int status = -1;
 408         struct sockaddr_in6 addr = {AF_INET6, 0, 0, ALL_IPV6_ROUTERS, ifindex};
 409         socklen_t alen = sizeof(addr);
 410         int sock = socket(AF_INET6, SOCK_RAW, IPPROTO_ICMPV6);
 411
 412         if (!connect(sock, (struct sockaddr*)&addr, sizeof(addr)) &&
 413                         !getsockname(sock, (struct sockaddr*)&addr, &alen)) {
 414                 *lladdr = addr.sin6_addr;
 415                 status = 0;
 416         }
 417
 418         close(sock);
 419
 420         return status;
 421 }
 422
 423 /*
 424  * DNS address selection criteria order :
 425  * - use IPv6 address with valid lifetime if none is yet selected
 426  * - use IPv6 address with a preferred lifetime if the already selected IPv6 address is deprecated
 427  * - use an IPv6 ULA address if the already selected IPv6 address is not an ULA address
 428  * - use the IPv6 address with the longest preferred lifetime
 429  */
 430 int odhcpd_get_interface_dns_addr(const struct interface *iface, struct in6_addr *addr)
 431 {
 432         time_t now = odhcpd_time();
 433         ssize_t m = -1;
 434
 435         for (size_t i = 0; i < iface->ia_addr_len; ++i) {
 436                 if (iface->ia_addr[i].valid <= (uint32_t)now)
 437                         continue;
 438
 439                 if (m < 0) {
 440                         m = i;
 441                         continue;
 442                 }
 443
 444                 if (iface->ia_addr[m].preferred >= (uint32_t)now &&
 445                                 iface->ia_addr[i].preferred < (uint32_t)now)
 446                         continue;
 447
 448                 if (IN6_IS_ADDR_ULA(&iface->ia_addr[i].addr.in6)) {
 449                         if (!IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6)) {
 450                                 m = i;
 451                                 continue;
 452                         }
 453                 } else if (IN6_IS_ADDR_ULA(&iface->ia_addr[m].addr.in6))
 454                         continue;
 455
 456                 if (iface->ia_addr[i].preferred > iface->ia_addr[m].preferred)
 457                         m = i;
 458         }
 459
 460         if (m >= 0) {
 461                 *addr = iface->ia_addr[m].addr.in6;
 462                 return 0;
 463         }
 464
 465         return odhcpd_get_linklocal_interface_address(iface->ifindex, addr);
 466 }
 467
 468 int odhcpd_setup_route(const struct in6_addr *addr, const int prefixlen,
 469                 const struct interface *iface, const struct in6_addr *gw,
 470                 const uint32_t metric, const bool add)
 471 {
 472         struct nl_msg *msg;
 473         struct rtmsg rtm = {
 474                 .rtm_family = AF_INET6,
 475                 .rtm_dst_len = prefixlen,
 476                 .rtm_src_len = 0,
 477                 .rtm_table = RT_TABLE_MAIN,
 478                 .rtm_protocol = (add ? RTPROT_STATIC : RTPROT_UNSPEC),
 479                 .rtm_scope = (add ? (gw ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK) : RT_SCOPE_NOWHERE),
 480                 .rtm_type = (add ? RTN_UNICAST : RTN_UNSPEC),
 481         };
 482         int ret = 0;
 483
 484         msg = nlmsg_alloc_simple(add ? RTM_NEWROUTE : RTM_DELROUTE,
 485                                         add ? NLM_F_CREATE | NLM_F_REPLACE : 0);
 486         if (!msg)
 487                 return -1;
 488
 489         nlmsg_append(msg, &rtm, sizeof(rtm), 0);
 490
 491         nla_put(msg, RTA_DST, sizeof(*addr), addr);
 492         nla_put_u32(msg, RTA_OIF, iface->ifindex);
 493         nla_put_u32(msg, RTA_PRIORITY, metric);
 494
 495         if (gw)
 496                 nla_put(msg, RTA_GATEWAY, sizeof(*gw), gw);
 497
 498         ret = nl_send_auto_complete(rtnl_socket, msg);
 499         nlmsg_free(msg);
 500
 501         if (ret < 0)
 502                 return ret;
 503
 504         return nl_wait_for_ack(rtnl_socket);
 505 }
 506
 507 int odhcpd_setup_proxy_neigh(const struct in6_addr *addr,
 508                 const struct interface *iface, const bool add)
 509 {
 510         struct nl_msg *msg;
 511         struct ndmsg ndm = {
 512                 .ndm_family = AF_INET6,
 513                 .ndm_flags = NTF_PROXY,
 514                 .ndm_ifindex = iface->ifindex,
 515         };
 516         int ret = 0, flags = NLM_F_REQUEST;
 517
 518         if (add)
 519                 flags |= NLM_F_REPLACE | NLM_F_CREATE;
 520
 521         msg = nlmsg_alloc_simple(add ? RTM_NEWNEIGH : RTM_DELNEIGH, flags);
 522         if (!msg)
 523                 return -1;
 524
 525         nlmsg_append(msg, &ndm, sizeof(ndm), 0);
 526
 527         nla_put(msg, NDA_DST, sizeof(*addr), addr);
 528
 529         ret = nl_send_auto_complete(rtnl_socket, msg);
 530         nlmsg_free(msg);
 531
 532         if (ret < 0)
 533                 return ret;
 534
 535         return nl_wait_for_ack(rtnl_socket);
 536 }
 537
 538 int odhcpd_setup_addr(struct odhcpd_ipaddr *addr,
 539                 const struct interface *iface, const bool v6,
 540                 const bool add)
 541 {
 542         struct nl_msg *msg;
 543         struct ifaddrmsg ifa = {
 544                 .ifa_family = v6 ? AF_INET6 : AF_INET,
 545                 .ifa_prefixlen = addr->prefix,
 546                 .ifa_flags = 0,
 547                 .ifa_scope = 0,
 548                 .ifa_index = iface->ifindex, };
 549         int ret = 0, flags = NLM_F_REQUEST;
 550
 551         if (add)
 552                 flags |= NLM_F_REPLACE | NLM_F_CREATE;
 553
 554         msg = nlmsg_alloc_simple(add ? RTM_NEWADDR : RTM_DELADDR, 0);
 555         if (!msg)
 556                 return -1;
 557
 558         nlmsg_append(msg, &ifa, sizeof(ifa), flags);
 559         nla_put(msg, IFA_LOCAL, v6 ? 16 : 4, &addr->addr);
 560         if (v6) {
 561                 struct ifa_cacheinfo cinfo = {  .ifa_prefered = 0xffffffffU,
 562                                                 .ifa_valid = 0xffffffffU,
 563                                                 .cstamp = 0,
 564                                                 .tstamp = 0 };
 565                 time_t now = odhcpd_time();
 566
 567                 if (addr->preferred) {
 568                         int64_t preferred = addr->preferred - now;
 569                         if (preferred < 0)
 570                                 preferred = 0;
 571                         else if (preferred > UINT32_MAX)
 572                                 preferred = UINT32_MAX;
 573
 574                         cinfo.ifa_prefered = preferred;
 575                 }
 576
 577                 if (addr->valid) {
 578                         int64_t valid = addr->valid - now;
 579                         if (valid <= 0) {
 580                                 nlmsg_free(msg);
 581                                 return -1;
 582                         }
 583                         else if (valid > UINT32_MAX)
 584                                 valid = UINT32_MAX;
 585
 586                         cinfo.ifa_valid = valid;
 587                 }
 588
 589                 nla_put(msg, IFA_CACHEINFO, sizeof(cinfo), &cinfo);
 590
 591                 nla_put_u32(msg, IFA_FLAGS, IFA_F_NOPREFIXROUTE);
 592         } else {
 593                 if (addr->broadcast.s_addr)
 594                         nla_put_u32(msg, IFA_BROADCAST, addr->broadcast.s_addr);
 595         }
 596
 597         ret = nl_send_auto_complete(rtnl_socket, msg);
 598         nlmsg_free(msg);
 599
 600         if (ret < 0)
 601                 return ret;
 602
 603         return nl_wait_for_ack(rtnl_socket);
 604 }
 605
 606 struct interface* odhcpd_get_interface_by_index(int ifindex)
 607 {
 608         struct interface *iface;
 609         list_for_each_entry(iface, &interfaces, head)
 610                 if (iface->ifindex == ifindex)
 611                         return iface;
 612
 613         return NULL;
 614 }
 615
 616
 617 struct interface* odhcpd_get_interface_by_name(const char *name)
 618 {
 619         struct interface *iface;
 620         list_for_each_entry(iface, &interfaces, head)
 621                 if (!strcmp(iface->ifname, name))
 622                         return iface;
 623
 624         return NULL;
 625 }
 626
 627
 628 struct interface* odhcpd_get_master_interface(void)
 629 {
 630         struct interface *iface;
 631         list_for_each_entry(iface, &interfaces, head)
 632                 if (iface->master)
 633                         return iface;
 634
 635         return NULL;
 636 }
 637
 638
 639 // Convenience function to receive and do basic validation of packets
 640 static void odhcpd_receive_packets(struct uloop_fd *u, _unused unsigned int events)
 641 {
 642         struct odhcpd_event *e = container_of(u, struct odhcpd_event, uloop);
 643
 644         uint8_t data_buf[8192], cmsg_buf[128];
 645         union {
 646                 struct sockaddr_in6 in6;
 647                 struct sockaddr_in in;
 648                 struct sockaddr_ll ll;
 649                 struct sockaddr_nl nl;
 650         } addr;
 651
 652         if (u->error) {
 653                 int ret = -1;
 654                 socklen_t ret_len = sizeof(ret);
 655                 getsockopt(u->fd, SOL_SOCKET, SO_ERROR, &ret, &ret_len);
 656                 u->error = false;
 657                 if (e->handle_error)
 658                         e->handle_error(e, ret);
 659         }
 660
 661         if (e->recv_msgs) {
 662                 e->recv_msgs(e);
 663                 return;
 664         }
 665
 666         while (true) {
 667                 struct iovec iov = {data_buf, sizeof(data_buf)};
 668                 struct msghdr msg = {
 669                         .msg_name = (void *) &addr,
 670                         .msg_namelen = sizeof(addr),
 671                         .msg_iov = &iov,
 672                         .msg_iovlen = 1,
 673                         .msg_control = cmsg_buf,
 674                         .msg_controllen = sizeof(cmsg_buf),
 675                         .msg_flags = 0
 676                 };
 677
 678                 ssize_t len = recvmsg(u->fd, &msg, MSG_DONTWAIT);
 679                 if (len < 0) {
 680                         if (errno == EAGAIN)
 681                                 break;
 682                         else
 683                                 continue;
 684                 }
 685
 686
 687                 // Extract destination interface
 688                 int destiface = 0;
 689                 int *hlim = NULL;
 690                 void *dest = NULL;
 691                 struct in6_pktinfo *pktinfo;
 692                 struct in_pktinfo *pkt4info;
 693                 for (struct cmsghdr *ch = CMSG_FIRSTHDR(&msg); ch != NULL; ch = CMSG_NXTHDR(&msg, ch)) {
 694                         if (ch->cmsg_level == IPPROTO_IPV6 &&
 695                                         ch->cmsg_type == IPV6_PKTINFO) {
 696                                 pktinfo = (struct in6_pktinfo*)CMSG_DATA(ch);
 697                                 destiface = pktinfo->ipi6_ifindex;
 698                                 dest = &pktinfo->ipi6_addr;
 699                         } else if (ch->cmsg_level == IPPROTO_IP &&
 700                                         ch->cmsg_type == IP_PKTINFO) {
 701                                 pkt4info = (struct in_pktinfo*)CMSG_DATA(ch);
 702                                 destiface = pkt4info->ipi_ifindex;
 703                                 dest = &pkt4info->ipi_addr;
 704                         } else if (ch->cmsg_level == IPPROTO_IPV6 &&
 705                                         ch->cmsg_type == IPV6_HOPLIMIT) {
 706                                 hlim = (int*)CMSG_DATA(ch);
 707                         }
 708                 }
 709
 710                 // Check hoplimit if received
 711                 if (hlim && *hlim != 255)
 712                         continue;
 713
 714                 // Detect interface for packet sockets
 715                 if (addr.ll.sll_family == AF_PACKET)
 716                         destiface = addr.ll.sll_ifindex;
 717
 718                 struct interface *iface =
 719                                 odhcpd_get_interface_by_index(destiface);
 720
 721                 if (!iface && addr.nl.nl_family != AF_NETLINK)
 722                         continue;
 723
 724                 char ipbuf[INET6_ADDRSTRLEN] = "kernel";
 725                 if (addr.ll.sll_family == AF_PACKET &&
 726                                 len >= (ssize_t)sizeof(struct ip6_hdr))
 727                         inet_ntop(AF_INET6, &data_buf[8], ipbuf, sizeof(ipbuf));
 728                 else if (addr.in6.sin6_family == AF_INET6)
 729                         inet_ntop(AF_INET6, &addr.in6.sin6_addr, ipbuf, sizeof(ipbuf));
 730                 else if (addr.in.sin_family == AF_INET)
 731                         inet_ntop(AF_INET, &addr.in.sin_addr, ipbuf, sizeof(ipbuf));
 732
 733                 syslog(LOG_DEBUG, "Received %li Bytes from %s%%%s", (long)len,
 734                                 ipbuf, (iface) ? iface->ifname : "netlink");
 735
 736                 e->handle_dgram(&addr, data_buf, len, iface, dest);
 737         }
 738 }
 739
 740 // Register events for the multiplexer
 741 int odhcpd_register(struct odhcpd_event *event)
 742 {
 743         event->uloop.cb = odhcpd_receive_packets;
 744         return uloop_fd_add(&event->uloop, ULOOP_READ |
 745                         ((event->handle_error) ? ULOOP_ERROR_CB : 0));
 746 }
 747
 748 int odhcpd_deregister(struct odhcpd_event *event)
 749 {
 750         event->uloop.cb = NULL;
 751         return uloop_fd_delete(&event->uloop);
 752 }
 753
 754 void odhcpd_process(struct odhcpd_event *event)
 755 {
 756         odhcpd_receive_packets(&event->uloop, 0);
 757 }
 758
 759 int odhcpd_urandom(void *data, size_t len)
 760 {
 761         return read(urandom_fd, data, len);
 762 }
 763
 764
 765 time_t odhcpd_time(void)
 766 {
 767         struct timespec ts;
 768         syscall(SYS_clock_gettime, CLOCK_MONOTONIC, &ts);
 769         return ts.tv_sec;
 770 }
 771
 772
 773 static const char hexdigits[] = "0123456789abcdef";
 774 static const int8_t hexvals[] = {
 775     -1, -1, -1, -1, -1, -1, -1, -1, -1, -2, -2, -1, -1, -2, -1, -1,
 776     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 777     -2, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 778      0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1,
 779     -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 780     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 781     -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 782     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 783 };
 784
 785 ssize_t odhcpd_unhexlify(uint8_t *dst, size_t len, const char *src)
 786 {
 787         size_t c;
 788         for (c = 0; c < len && src[0] && src[1]; ++c) {
 789                 int8_t x = (int8_t)*src++;
 790                 int8_t y = (int8_t)*src++;
 791                 if (x < 0 || (x = hexvals[x]) < 0
 792                                 || y < 0 || (y = hexvals[y]) < 0)
 793                         return -1;
 794                 dst[c] = x << 4 | y;
 795                 while (((int8_t)*src) < 0 ||
 796                                 (*src && hexvals[(uint8_t)*src] < 0))
 797                         src++;
 798         }
 799
 800         return c;
 801 }
 802
 803
 804 void odhcpd_hexlify(char *dst, const uint8_t *src, size_t len)
 805 {
 806         for (size_t i = 0; i < len; ++i) {
 807                 *dst++ = hexdigits[src[i] >> 4];
 808                 *dst++ = hexdigits[src[i] & 0x0f];
 809         }
 810         *dst = 0;
 811 }
 812
 813
 814 int odhcpd_bmemcmp(const void *av, const void *bv, size_t bits)
 815 {
 816         const uint8_t *a = av, *b = bv;
 817         size_t bytes = bits / 8;
 818         bits %= 8;
 819
 820         int res = memcmp(a, b, bytes);
 821         if (res == 0 && bits > 0)
 822                 res = (a[bytes] >> (8 - bits)) - (b[bytes] >> (8 - bits));
 823
 824         return res;
 825 }
 826
 827
 828 void odhcpd_bmemcpy(void *av, const void *bv, size_t bits)
 829 {
 830         uint8_t *a = av;
 831         const uint8_t *b = bv;
 832
 833         size_t bytes = bits / 8;
 834         bits %= 8;
 835         memcpy(a, b, bytes);
 836
 837         if (bits > 0) {
 838                 uint8_t mask = (1 << (8 - bits)) - 1;
 839                 a[bytes] = (a[bytes] & mask) | ((~mask) & b[bytes]);
 840         }
 841 }
 842
 843
 844 int odhcpd_netmask2bitlen(bool inet6, void *mask)
 845 {
 846         int bits;
 847         struct in_addr *v4;
 848         struct in6_addr *v6;
 849
 850         if (inet6)
 851                 for (bits = 0, v6 = mask;
 852                      bits < 128 && (v6->s6_addr[bits / 8] << (bits % 8)) & 128;
 853                      bits++);
 854         else
 855                 for (bits = 0, v4 = mask;
 856                      bits < 32 && (ntohl(v4->s_addr) << bits) & 0x80000000;
 857                      bits++);
 858
 859         return bits;
 860 }
 861
 862 bool odhcpd_bitlen2netmask(bool inet6, unsigned int bits, void *mask)
 863 {
 864         uint8_t b;
 865         struct in_addr *v4;
 866         struct in6_addr *v6;
 867
 868         if (inet6)
 869         {
 870                 if (bits > 128)
 871                         return false;
 872
 873                 v6 = mask;
 874
 875                 for (unsigned int i = 0; i < sizeof(v6->s6_addr); i++)
 876                 {
 877                         b = (bits > 8) ? 8 : bits;
 878                         v6->s6_addr[i] = (uint8_t)(0xFF << (8 - b));
 879                         bits -= b;
 880                 }
 881         }
 882         else
 883         {
 884                 if (bits > 32)
 885                         return false;
 886
 887                 v4 = mask;
 888                 v4->s_addr = bits ? htonl(~((1 << (32 - bits)) - 1)) : 0;
 889         }
 890
 891         return true;
 892 }