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