interface.c

   1 /*
   2  * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
   3  * Copyright (C) 2014 Felix Fietkau <nbd@openwrt.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License version 2.1
   7  * as published by 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 #define _GNU_SOURCE
  16 #include <sys/socket.h>
  17 #include <sys/ioctl.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <sys/utsname.h>
  21 #include <net/if.h>
  22 #include <netinet/in.h>
  23 #include <arpa/inet.h>
  24 #include <sys/types.h>
  25
  26 #include <ifaddrs.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30 #include <stdio.h>
  31 #include <errno.h>
  32
  33 #include <libubox/usock.h>
  34 #include <libubox/uloop.h>
  35 #include <libubox/avl-cmp.h>
  36 #include <libubox/utils.h>
  37 #include "interface.h"
  38 #include "util.h"
  39 #include "dns.h"
  40 #include "announce.h"
  41
  42 static int
  43 interface_send_packet4(struct interface *iface, struct iovec *iov, int iov_len)
  44 {
  45         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
  46         static struct sockaddr_in a;
  47         static struct msghdr m = {
  48                 .msg_name = (struct sockaddr *) &a,
  49                 .msg_namelen = sizeof(a),
  50                 .msg_control = cmsg_data,
  51                 .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
  52         };
  53         struct in_pktinfo *pkti;
  54         struct cmsghdr *cmsg;
  55         int fd = iface->fd.fd;
  56
  57         a.sin_family = AF_INET;
  58         a.sin_port = htons(MCAST_PORT);
  59         m.msg_iov = iov;
  60         m.msg_iovlen = iov_len;
  61
  62         memset(cmsg_data, 0, sizeof(cmsg_data));
  63         cmsg = CMSG_FIRSTHDR(&m);
  64         cmsg->cmsg_len = m.msg_controllen;
  65         cmsg->cmsg_level = IPPROTO_IP;
  66         cmsg->cmsg_type = IP_PKTINFO;
  67
  68         pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
  69         pkti->ipi_ifindex = iface->ifindex;
  70
  71         a.sin_addr.s_addr = inet_addr(MCAST_ADDR);
  72
  73         return sendmsg(fd, &m, 0);
  74 }
  75
  76 static int
  77 interface_send_packet6(struct interface *iface, struct iovec *iov, int iov_len)
  78 {
  79         static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in6_pktinfo)) / sizeof(size_t)) + 1];
  80         static struct sockaddr_in6 a;
  81         static struct msghdr m = {
  82                 .msg_name = (struct sockaddr *) &a,
  83                 .msg_namelen = sizeof(a),
  84                 .msg_control = cmsg_data,
  85                 .msg_controllen = CMSG_LEN(sizeof(struct in6_pktinfo)),
  86         };
  87         struct in6_pktinfo *pkti;
  88         struct cmsghdr *cmsg;
  89         int fd = iface->fd.fd;
  90
  91         a.sin6_family = AF_INET6;
  92         a.sin6_port = htons(MCAST_PORT);
  93         m.msg_iov = iov;
  94         m.msg_iovlen = iov_len;
  95
  96         memset(cmsg_data, 0, sizeof(cmsg_data));
  97         cmsg = CMSG_FIRSTHDR(&m);
  98         cmsg->cmsg_len = m.msg_controllen;
  99         cmsg->cmsg_level = IPPROTO_IPV6;
 100         cmsg->cmsg_type = IPV6_PKTINFO;
 101
 102         pkti = (struct in6_pktinfo*) CMSG_DATA(cmsg);
 103         pkti->ipi6_ifindex = iface->ifindex;
 104
 105         inet_pton(AF_INET6, MCAST_ADDR6, &a.sin6_addr);
 106
 107         return sendmsg(fd, &m, 0);
 108 }
 109
 110 int
 111 interface_send_packet(struct interface *iface, struct iovec *iov, int iov_len)
 112 {
 113         if (iface->v6)
 114                 return interface_send_packet6(iface, iov, iov_len);
 115
 116         return interface_send_packet4(iface, iov, iov_len);
 117 }
 118
 119 static void interface_close(struct interface *iface)
 120 {
 121         if (iface->fd.fd < 0)
 122                 return;
 123
 124         announce_free(iface);
 125         uloop_fd_delete(&iface->fd);
 126         close(iface->fd.fd);
 127         iface->fd.fd = -1;
 128 }
 129
 130 static void interface_free(struct interface *iface)
 131 {
 132         interface_close(iface);
 133         free(iface);
 134 }
 135
 136 static void
 137 read_socket4(struct uloop_fd *u, unsigned int events)
 138 {
 139         struct interface *iface = container_of(u, struct interface, fd);
 140         static uint8_t buffer[8 * 1024];
 141         struct iovec iov[1];
 142         char cmsg[CMSG_SPACE(sizeof(struct in_pktinfo)) + CMSG_SPACE(sizeof(int)) + 1];
 143         struct cmsghdr *cmsgptr;
 144         struct msghdr msg;
 145         socklen_t len;
 146         struct sockaddr_in from;
 147         int flags = 0, ifindex = -1;
 148         uint8_t ttl = 0;
 149         struct in_pktinfo *inp = NULL;
 150
 151         if (u->eof) {
 152                 interface_close(iface);
 153                 uloop_timeout_set(&iface->reconnect, 1000);
 154                 return;
 155         }
 156
 157         iov[0].iov_base = buffer;
 158         iov[0].iov_len = sizeof(buffer);
 159
 160         memset(&msg, 0, sizeof(msg));
 161         msg.msg_name = (struct sockaddr *) &from;
 162         msg.msg_namelen = sizeof(struct sockaddr_in);
 163         msg.msg_iov = iov;
 164         msg.msg_iovlen = 1;
 165         msg.msg_control = &cmsg;
 166         msg.msg_controllen = sizeof(cmsg);
 167
 168         len = recvmsg(u->fd, &msg, flags);
 169         if (len == -1) {
 170                 perror("read failed");
 171                 return;
 172         }
 173         for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL; cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)) {
 174                 void *c = CMSG_DATA(cmsgptr);
 175
 176                 switch (cmsgptr->cmsg_type) {
 177                 case IP_PKTINFO:
 178                         inp = ((struct in_pktinfo *) c);
 179                         break;
 180
 181                 case IP_TTL:
 182                         ttl = (uint8_t) *((int *) c);
 183                         break;
 184
 185                 default:
 186                         fprintf(stderr, "unknown cmsg %x\n", cmsgptr->cmsg_type);
 187                         return;
 188                 }
 189         }
 190
 191         if (ttl != 255)
 192                 return;
 193
 194         if (debug > 1) {
 195                 char buf[256];
 196
 197                 fprintf(stderr, "iface: %s\n", iface->name);
 198                 fprintf(stderr, "  v6: %d\n", iface->v6);
 199                 fprintf(stderr, "  multicast: %d\n", iface->multicast);
 200                 inet_ntop(AF_INET, &from.sin_addr, buf, 256);
 201                 fprintf(stderr, "  src %s:%d\n", buf, from.sin_port);
 202                 inet_ntop(AF_INET, &inp->ipi_spec_dst, buf, 256);
 203                 fprintf(stderr, "  dst %s\n", buf);
 204                 inet_ntop(AF_INET, &inp->ipi_addr, buf, 256);
 205                 fprintf(stderr, "  real %s\n", buf);
 206         }
 207
 208         if (inp->ipi_ifindex != iface->ifindex)
 209                 fprintf(stderr, "invalid iface index %d != %d\n", ifindex, iface->ifindex);
 210         else
 211                 dns_handle_packet(iface, buffer, len, 0);
 212 }
 213
 214 static void
 215 read_socket6(struct uloop_fd *u, unsigned int events)
 216 {
 217         struct interface *iface = container_of(u, struct interface, fd);
 218         static uint8_t buffer[8 * 1024];
 219         struct iovec iov[1];
 220         char cmsg6[CMSG_SPACE(sizeof(struct in6_pktinfo)) + CMSG_SPACE(sizeof(int)) + 1];
 221         struct cmsghdr *cmsgptr;
 222         struct msghdr msg;
 223         socklen_t len;
 224         struct sockaddr_in6 from;
 225         int flags = 0, ifindex = -1;
 226         int ttl = 0;
 227         struct in6_pktinfo *inp = NULL;
 228
 229         if (u->eof) {
 230                 interface_close(iface);
 231                 uloop_timeout_set(&iface->reconnect, 1000);
 232                 return;
 233         }
 234
 235         iov[0].iov_base = buffer;
 236         iov[0].iov_len = sizeof(buffer);
 237
 238         memset(&msg, 0, sizeof(msg));
 239         msg.msg_name = (struct sockaddr *) &from;
 240         msg.msg_namelen = sizeof(struct sockaddr_in6);
 241         msg.msg_iov = iov;
 242         msg.msg_iovlen = 1;
 243         msg.msg_control = &cmsg6;
 244         msg.msg_controllen = sizeof(cmsg6);
 245
 246         len = recvmsg(u->fd, &msg, flags);
 247         if (len == -1) {
 248                 perror("read failed");
 249                 return;
 250         }
 251         for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL; cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)) {
 252                 void *c = CMSG_DATA(cmsgptr);
 253
 254                 switch (cmsgptr->cmsg_type) {
 255                 case IPV6_PKTINFO:
 256                         inp = ((struct in6_pktinfo *) c);
 257                         break;
 258
 259                 case IPV6_HOPLIMIT:
 260                         ttl = (uint8_t) *((int *) c);
 261                         break;
 262
 263                 default:
 264                         fprintf(stderr, "unknown cmsg %x\n", cmsgptr->cmsg_type);
 265                         return;
 266                 }
 267         }
 268
 269         if (ttl != 255)
 270                 return;
 271
 272         if (debug > 1) {
 273                 char buf[256];
 274
 275                 fprintf(stderr, "iface: %s\n", iface->name);
 276                 fprintf(stderr, "  v6: %d\n", iface->v6);
 277                 fprintf(stderr, "  multicast: %d\n", iface->multicast);
 278                 inet_ntop(AF_INET6, &from.sin6_addr, buf, 256);
 279                 fprintf(stderr, "  src %s:%d\n", buf, from.sin6_port);
 280                 inet_ntop(AF_INET6, &inp->ipi6_addr, buf, 256);
 281                 fprintf(stderr, "  dst %s\n", buf);
 282         }
 283
 284         if (inp->ipi6_ifindex != iface->ifindex)
 285                 fprintf(stderr, "invalid iface index %d != %d\n", ifindex, iface->ifindex);
 286         else
 287                 dns_handle_packet(iface, buffer, len, 0);
 288 }
 289
 290 static int
 291 interface_mcast_setup4(struct interface *iface)
 292 {
 293         struct ip_mreqn mreq;
 294         uint8_t ttl = 255;
 295         int no = 0;
 296         struct sockaddr_in sa = { 0 };
 297         int fd = iface->fd.fd;
 298
 299         sa.sin_family = AF_INET;
 300         sa.sin_port = htons(MCAST_PORT);
 301         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 302
 303         memset(&mreq, 0, sizeof(mreq));
 304         mreq.imr_address.s_addr = iface->v4_addr.s_addr;
 305         mreq.imr_multiaddr = sa.sin_addr;
 306         mreq.imr_ifindex = iface->ifindex;
 307
 308         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 309                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 310
 311         /* Some network drivers have issues with dropping membership of
 312          * mcast groups when the iface is down, but don't allow rejoining
 313          * when it comes back up. This is an ugly workaround
 314          * -- this was copied from avahi --
 315          */
 316         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 317
 318         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 319                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 320                 close(fd);
 321                 fd = -1;
 322                 return -1;
 323         }
 324
 325         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 326                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 327
 328         return 0;
 329 }
 330
 331 static int
 332 interface_socket_setup6(struct interface *iface)
 333 {
 334         struct ipv6_mreq mreq;
 335         int ttl = 255;
 336         int no = 0;
 337         struct sockaddr_in6 sa = { 0 };
 338         int fd = iface->fd.fd;
 339
 340         sa.sin6_family = AF_INET6;
 341         sa.sin6_port = htons(MCAST_PORT);
 342         inet_pton(AF_INET6, MCAST_ADDR6, &sa.sin6_addr);
 343
 344         memset(&mreq, 0, sizeof(mreq));
 345         mreq.ipv6mr_multiaddr = sa.sin6_addr;
 346         mreq.ipv6mr_interface = iface->ifindex;
 347
 348         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 349                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_HOPS\n");
 350
 351         setsockopt(fd, IPPROTO_IPV6, IPV6_LEAVE_GROUP, &mreq, sizeof(mreq));
 352         if (setsockopt(fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 353                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 354                 close(fd);
 355                 fd = -1;
 356                 return -1;
 357         }
 358
 359         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 360                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_LOOP\n");
 361
 362         return 0;
 363 }
 364
 365 static void
 366 reconnect_socket4(struct uloop_timeout *timeout)
 367 {
 368         struct interface *iface = container_of(timeout, struct interface, reconnect);
 369         int yes = 1;
 370
 371         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK | USOCK_IPV4ONLY,
 372                 (iface->multicast) ? (iface->mcast_addr) : (iface->v4_addrs), "5353");
 373         if (iface->fd.fd < 0) {
 374                 fprintf(stderr, "failed to add listener %s: %s\n", iface->mcast_addr, strerror(errno));
 375                 goto retry;
 376         }
 377
 378         if (setsockopt(iface->fd.fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 379                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 380
 381         if (setsockopt(iface->fd.fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 382                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 383
 384         if (setsockopt(iface->fd.fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 385                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 386
 387         if (iface->multicast && interface_mcast_setup4(iface)) {
 388                 iface->fd.fd = -1;
 389                 goto retry;
 390         }
 391
 392         uloop_fd_add(&iface->fd, ULOOP_READ);
 393         if (iface->multicast) {
 394                 dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR, 1);
 395                 announce_init(iface);
 396         }
 397
 398         return;
 399
 400 retry:
 401         uloop_timeout_set(timeout, 1000);
 402 }
 403
 404 static void
 405 reconnect_socket6(struct uloop_timeout *timeout)
 406 {
 407         struct interface *iface = container_of(timeout, struct interface, reconnect);
 408         char mcast_addr[128];
 409         int ttl = 255;
 410         int yes = 1;
 411
 412         snprintf(mcast_addr, sizeof(mcast_addr), "%s%%%s", (iface->multicast) ? (iface->mcast_addr) : (iface->v6_addrs), iface->name);
 413         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK | USOCK_IPV6ONLY, mcast_addr, "5353");
 414         if (iface->fd.fd < 0) {
 415                 fprintf(stderr, "failed to add listener %s: %s\n", mcast_addr, strerror(errno));
 416                 goto retry;
 417         }
 418
 419         if (setsockopt(iface->fd.fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 420                 fprintf(stderr, "ioctl failed: IPV6_UNICAST_HOPS\n");
 421
 422         if (setsockopt(iface->fd.fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &yes, sizeof(yes)) < 0)
 423                 fprintf(stderr, "ioctl failed: IPV6_RECVPKTINFO\n");
 424
 425         if (setsockopt(iface->fd.fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &yes, sizeof(yes)) < 0)
 426                 fprintf(stderr, "ioctl failed: IPV6_RECVHOPLIMIT\n");
 427
 428         if (setsockopt(iface->fd.fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 429                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 430
 431         if (iface->multicast && interface_socket_setup6(iface)) {
 432                 iface->fd.fd = -1;
 433                 goto retry;
 434         }
 435
 436         uloop_fd_add(&iface->fd, ULOOP_READ);
 437
 438         if (iface->multicast) {
 439                 dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR, 1);
 440                 announce_init(iface);
 441         }
 442
 443         return;
 444
 445 retry:
 446         uloop_timeout_set(timeout, 1000);
 447 }
 448
 449
 450 static void interface_start(struct interface *iface)
 451 {
 452         if (iface->v6) {
 453                 iface->fd.cb = read_socket6;
 454                 iface->reconnect.cb = reconnect_socket6;
 455         } else {
 456                 iface->fd.cb = read_socket4;
 457                 iface->reconnect.cb = reconnect_socket4;
 458         }
 459         uloop_timeout_set(&iface->reconnect, 100);
 460 }
 461
 462 static void
 463 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 464                 struct vlist_node *node_old)
 465 {
 466         struct interface *iface;
 467
 468         if (node_old) {
 469                 iface = container_of(node_old, struct interface, node);
 470                 interface_free(iface);
 471         }
 472
 473         if (node_new) {
 474                 iface = container_of(node_new, struct interface, node);
 475                 interface_start(iface);
 476         }
 477 }
 478
 479 static struct interface* _interface_add(const char *name, int multicast, int v6)
 480 {
 481         struct interface *iface;
 482         char *name_buf;
 483         char *id_buf;
 484
 485         iface = calloc_a(sizeof(*iface),
 486                 &name_buf, strlen(name) + 1,
 487                 &id_buf, strlen(name) + 5);
 488
 489         sprintf(id_buf, "%d_%d_%s", multicast, v6, name);
 490         iface->name = strcpy(name_buf, name);
 491         iface->id = id_buf;
 492         iface->ifindex = if_nametoindex(name);
 493         iface->fd.fd = -1;
 494         iface->multicast = multicast;
 495         iface->v6 = v6;
 496         if (v6)
 497                 iface->mcast_addr = MCAST_ADDR6;
 498         else
 499                 iface->mcast_addr = MCAST_ADDR;
 500
 501         if (iface->ifindex <= 0)
 502                 goto error;
 503
 504         vlist_add(&interfaces, &iface->node, iface->id);
 505         return iface;
 506
 507 error:
 508         free(iface);
 509         return NULL;
 510 }
 511
 512 int interface_add(const char *name)
 513 {
 514         struct interface *v4 = NULL, *v6 = NULL, *unicast;
 515         struct ifaddrs *ifap, *ifa;
 516
 517         getifaddrs(&ifap);
 518
 519         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 520                 if (strcmp(ifa->ifa_name, name))
 521                         continue;
 522                 if (ifa->ifa_addr->sa_family == AF_INET && !v4) {
 523                         struct sockaddr_in *sa;
 524
 525                         if (cfg_proto && (cfg_proto != 4))
 526                                 continue;
 527
 528                         unicast = _interface_add(name, 0, 0);
 529                         if (!unicast)
 530                                 continue;
 531                         sa = (struct sockaddr_in *) ifa->ifa_addr;
 532                         memcpy(&unicast->v4_addr, &sa->sin_addr, sizeof(unicast->v4_addr));
 533                         inet_ntop(AF_INET, &sa->sin_addr, unicast->v4_addrs, sizeof(unicast->v4_addrs));
 534
 535                         v4 = _interface_add(name, 1, 0);
 536                         if (!v4)
 537                                 continue;
 538                         memcpy(&v4->v4_addr, &sa->sin_addr, sizeof(v4->v4_addr));
 539                         inet_ntop(AF_INET, &sa->sin_addr, v4->v4_addrs, sizeof(v4->v4_addrs));
 540
 541                         v4->peer = unicast;
 542                         unicast->peer = v4;
 543                 }
 544
 545                 if (ifa->ifa_addr->sa_family == AF_INET6 && !v6) {
 546                         uint8_t ll_prefix[] = {0xfe, 0x80 };
 547                         struct sockaddr_in6 *sa6;
 548
 549                         if (cfg_proto && (cfg_proto != 6))
 550                                 continue;
 551
 552                         sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
 553                         if (memcmp(&sa6->sin6_addr, &ll_prefix, 2))
 554                                 continue;
 555
 556                         unicast = _interface_add(name, 0, 1);
 557                         if (!unicast)
 558                                 continue;
 559                         memcpy(&unicast->v6_addr, &sa6->sin6_addr, sizeof(unicast->v6_addr));
 560                         inet_ntop(AF_INET6, &sa6->sin6_addr, unicast->v6_addrs, sizeof(unicast->v6_addrs));
 561
 562                         v6 = _interface_add(name, 1, 1);
 563                         if (!v6)
 564                                 continue;
 565                         memcpy(&v6->v6_addr, &sa6->sin6_addr, sizeof(v6->v6_addr));
 566                         inet_ntop(AF_INET6, &sa6->sin6_addr, v6->v6_addrs, sizeof(v6->v6_addrs));
 567
 568                         v6->peer = unicast;
 569                         unicast->peer = v6;
 570                 }
 571         }
 572
 573         freeifaddrs(ifap);
 574
 575         return !v4 && !v6;
 576 }
 577
 578 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);