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                         break;
 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)) + 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
 227         if (u->eof) {
 228                 interface_close(iface);
 229                 uloop_timeout_set(&iface->reconnect, 1000);
 230                 return;
 231         }
 232
 233         iov[0].iov_base = buffer;
 234         iov[0].iov_len = sizeof(buffer);
 235
 236         memset(&msg, 0, sizeof(msg));
 237         msg.msg_name = (struct sockaddr *) &from;
 238         msg.msg_namelen = (iface->v6) ? (sizeof(struct sockaddr_in6)) : (sizeof(struct sockaddr_in));
 239         msg.msg_iov = iov;
 240         msg.msg_iovlen = 1;
 241         msg.msg_control = &cmsg6;
 242         msg.msg_controllen = sizeof(cmsg6);
 243
 244         len = recvmsg(u->fd, &msg, flags);
 245         if (len == -1) {
 246                 perror("read failed");
 247                 return;
 248         }
 249         for (cmsgptr = CMSG_FIRSTHDR(&msg); cmsgptr != NULL; cmsgptr = CMSG_NXTHDR(&msg, cmsgptr)) {
 250                 void *c = CMSG_DATA(cmsgptr);
 251
 252                 if (cmsgptr->cmsg_level == IPPROTO_IP && cmsgptr->cmsg_type == IP_PKTINFO)
 253                         ifindex = ((struct in_pktinfo *) c)->ipi_ifindex;
 254                 else if (cmsgptr->cmsg_level == IPPROTO_IPV6 && cmsgptr->cmsg_type == IPV6_PKTINFO)
 255                         ifindex = ((struct in6_pktinfo *) c)->ipi6_ifindex;
 256         }
 257         if (ifindex != iface->ifindex)
 258                 fprintf(stderr, "invalid iface index %d != %d\n", ifindex, iface->ifindex);
 259         else
 260                 dns_handle_packet(iface, buffer, len, 0);
 261 }
 262
 263 static int
 264 interface_mcast_setup4(struct interface *iface)
 265 {
 266         struct ip_mreqn mreq;
 267         uint8_t ttl = 255;
 268         int no = 0;
 269         struct sockaddr_in sa = { 0 };
 270         int fd = iface->fd.fd;
 271
 272         sa.sin_family = AF_INET;
 273         sa.sin_port = htons(MCAST_PORT);
 274         inet_pton(AF_INET, MCAST_ADDR, &sa.sin_addr);
 275
 276         memset(&mreq, 0, sizeof(mreq));
 277         mreq.imr_address.s_addr = iface->v4_addr.s_addr;
 278         mreq.imr_multiaddr = sa.sin_addr;
 279         mreq.imr_ifindex = iface->ifindex;
 280
 281         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0)
 282                 fprintf(stderr, "ioctl failed: IP_MULTICAST_TTL\n");
 283
 284         /* Some network drivers have issues with dropping membership of
 285          * mcast groups when the iface is down, but don't allow rejoining
 286          * when it comes back up. This is an ugly workaround
 287          * -- this was copied from avahi --
 288          */
 289         setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 290
 291         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 292                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 293                 close(fd);
 294                 fd = -1;
 295                 return -1;
 296         }
 297
 298         if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 299                 fprintf(stderr, "ioctl failed: IP_MULTICAST_LOOP\n");
 300
 301         return 0;
 302 }
 303
 304 static int
 305 interface_socket_setup6(struct interface *iface)
 306 {
 307         struct ipv6_mreq mreq;
 308         int ttl = 255;
 309         int no = 0;
 310         struct sockaddr_in6 sa = { 0 };
 311         int fd = iface->fd.fd;
 312
 313         sa.sin6_family = AF_INET6;
 314         sa.sin6_port = htons(MCAST_PORT);
 315         inet_pton(AF_INET6, MCAST_ADDR6, &sa.sin6_addr);
 316
 317         memset(&mreq, 0, sizeof(mreq));
 318         mreq.ipv6mr_multiaddr = sa.sin6_addr;
 319         mreq.ipv6mr_interface = iface->ifindex;
 320
 321         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 322                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_HOPS\n");
 323
 324         setsockopt(fd, IPPROTO_IPV6, IPV6_LEAVE_GROUP, &mreq, sizeof(mreq));
 325         if (setsockopt(fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
 326                 fprintf(stderr, "failed to join multicast group: %s\n", strerror(errno));
 327                 close(fd);
 328                 fd = -1;
 329                 return -1;
 330         }
 331
 332         if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &no, sizeof(no)) < 0)
 333                 fprintf(stderr, "ioctl failed: IPV6_MULTICAST_LOOP\n");
 334
 335         return 0;
 336 }
 337
 338 static void
 339 reconnect_socket4(struct uloop_timeout *timeout)
 340 {
 341         struct interface *iface = container_of(timeout, struct interface, reconnect);
 342         int yes = 1;
 343
 344         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK | USOCK_IPV4ONLY,
 345                 (iface->multicast) ? (iface->mcast_addr) : (iface->v4_addrs), "5353");
 346         if (iface->fd.fd < 0) {
 347                 fprintf(stderr, "failed to add listener %s: %s\n", iface->mcast_addr, strerror(errno));
 348                 goto retry;
 349         }
 350
 351         if (setsockopt(iface->fd.fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 352                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 353
 354         if (setsockopt(iface->fd.fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0)
 355                 fprintf(stderr, "ioctl failed: IP_RECVTTL\n");
 356
 357         if (setsockopt(iface->fd.fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0)
 358                 fprintf(stderr, "ioctl failed: IP_PKTINFO\n");
 359
 360         if (iface->multicast && interface_mcast_setup4(iface)) {
 361                 iface->fd.fd = -1;
 362                 goto retry;
 363         }
 364
 365         uloop_fd_add(&iface->fd, ULOOP_READ);
 366         dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR);
 367         announce_init(iface);
 368
 369         return;
 370
 371 retry:
 372         uloop_timeout_set(timeout, 1000);
 373 }
 374
 375 static void
 376 reconnect_socket6(struct uloop_timeout *timeout)
 377 {
 378         struct interface *iface = container_of(timeout, struct interface, reconnect);
 379         char mcast_addr[128];
 380         int ttl = 255;
 381         int yes = 1;
 382
 383         snprintf(mcast_addr, sizeof(mcast_addr), "%s%%%s", iface->mcast_addr, iface->name);
 384         iface->fd.fd = usock(USOCK_UDP | USOCK_SERVER | USOCK_NONBLOCK | USOCK_IPV6ONLY, mcast_addr, "5353");
 385         if (iface->fd.fd < 0) {
 386                 fprintf(stderr, "failed to add listener %s: %s\n", mcast_addr, strerror(errno));
 387                 goto retry;
 388         }
 389
 390         if (setsockopt(iface->fd.fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)) < 0)
 391                 fprintf(stderr, "ioctl failed: IPV6_UNICAST_HOPS\n");
 392
 393         if (setsockopt(iface->fd.fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &yes, sizeof(yes)) < 0)
 394                 fprintf(stderr, "ioctl failed: IPV6_RECVPKTINFO\n");
 395
 396         if (setsockopt(iface->fd.fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &yes, sizeof(yes)) < 0)
 397                 fprintf(stderr, "ioctl failed: IPV6_RECVHOPLIMIT\n");
 398
 399         if (setsockopt(iface->fd.fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0)
 400                 fprintf(stderr, "ioctl failed: SO_REUSEADDR\n");
 401
 402         if (iface->multicast && interface_socket_setup6(iface)) {
 403                 iface->fd.fd = -1;
 404                 goto retry;
 405         }
 406
 407         uloop_fd_add(&iface->fd, ULOOP_READ);
 408         dns_send_question(iface, "_services._dns-sd._udp.local", TYPE_PTR);
 409         announce_init(iface);
 410         return;
 411
 412 retry:
 413         uloop_timeout_set(timeout, 1000);
 414 }
 415
 416
 417 static void interface_start(struct interface *iface)
 418 {
 419         if (iface->v6) {
 420                 iface->fd.cb = read_socket6;
 421                 iface->reconnect.cb = reconnect_socket6;
 422         } else {
 423                 iface->fd.cb = read_socket4;
 424                 iface->reconnect.cb = reconnect_socket4;
 425         }
 426         uloop_timeout_set(&iface->reconnect, 100);
 427 }
 428
 429 static void
 430 iface_update_cb(struct vlist_tree *tree, struct vlist_node *node_new,
 431                 struct vlist_node *node_old)
 432 {
 433         struct interface *iface;
 434
 435         if (node_old) {
 436                 iface = container_of(node_old, struct interface, node);
 437                 interface_free(iface);
 438         }
 439
 440         if (node_new) {
 441                 iface = container_of(node_new, struct interface, node);
 442                 interface_start(iface);
 443         }
 444 }
 445
 446 static struct interface* _interface_add(const char *name, int multicast, int v6)
 447 {
 448         struct interface *iface;
 449         char *name_buf;
 450         char *id_buf;
 451
 452         iface = calloc_a(sizeof(*iface),
 453                 &name_buf, strlen(name) + 1,
 454                 &id_buf, strlen(name) + 3);
 455
 456         sprintf(id_buf, "%d_%s", v6, name);
 457         iface->name = strcpy(name_buf, name);
 458         iface->id = id_buf;
 459         iface->ifindex = if_nametoindex(name);
 460         iface->fd.fd = -1;
 461         iface->multicast = multicast;
 462         iface->v6 = v6;
 463         if (v6)
 464                 iface->mcast_addr = MCAST_ADDR6;
 465         else
 466                 iface->mcast_addr = MCAST_ADDR;
 467
 468         if (iface->ifindex <= 0)
 469                 goto error;
 470
 471         vlist_add(&interfaces, &iface->node, iface->id);
 472         return iface;
 473
 474 error:
 475         free(iface);
 476         return NULL;
 477 }
 478
 479 int interface_add(const char *name)
 480 {
 481         struct interface *v4 = NULL, *v6 = NULL, *unicast;
 482         struct ifaddrs *ifap, *ifa;
 483
 484         getifaddrs(&ifap);
 485
 486         for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
 487                 if (strcmp(ifa->ifa_name, name))
 488                         continue;
 489                 if (ifa->ifa_addr->sa_family == AF_INET && !v4) {
 490                         struct sockaddr_in *sa;
 491
 492                         if (cfg_proto && (cfg_proto != 4))
 493                                 continue;
 494
 495                         v4 = _interface_add(name, 1, 0);
 496                         if (!v4)
 497                                 continue;
 498
 499                         sa = (struct sockaddr_in *) ifa->ifa_addr;
 500                         memcpy(&v4->v4_addr, &sa->sin_addr, sizeof(v4->v4_addr));
 501                         inet_ntop(AF_INET, &sa->sin_addr, v4->v4_addrs, sizeof(v4->v4_addrs));
 502
 503                         unicast = _interface_add(name, 0, 0);
 504                         if (!unicast)
 505                                 continue;
 506
 507                         memcpy(&unicast->v4_addr, &sa->sin_addr, sizeof(unicast->v4_addr));
 508                         inet_ntop(AF_INET, &sa->sin_addr, unicast->v4_addrs, sizeof(unicast->v4_addrs));
 509                 }
 510
 511                 if (ifa->ifa_addr->sa_family == AF_INET6 && !v6) {
 512                         uint8_t ll_prefix[] = {0xfe, 0x80 };
 513                         struct sockaddr_in6 *sa6;
 514
 515                         if (cfg_proto && (cfg_proto != 6))
 516                                 continue;
 517
 518                         sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
 519                         if (memcmp(&sa6->sin6_addr, &ll_prefix, 2))
 520                                 continue;
 521
 522                         v6 = _interface_add(name, 1, 1);
 523                         if (!v6)
 524                                 continue;
 525                         memcpy(&v6->v6_addr, &sa6->sin6_addr, sizeof(v6->v6_addr));
 526                         inet_ntop(AF_INET6, &sa6->sin6_addr, v6->v6_addrs, sizeof(v6->v6_addrs));
 527
 528                         unicast = _interface_add(name, 0, 1);
 529                         if (!unicast)
 530                                 continue;
 531
 532                         memcpy(&unicast->v6_addr, &sa6->sin6_addr, sizeof(unicast->v6_addr));
 533                         inet_ntop(AF_INET6, &sa6->sin6_addr, unicast->v6_addrs, sizeof(unicast->v6_addrs));
 534                 }
 535         }
 536
 537         freeifaddrs(ifap);
 538
 539         return !v4 && !v6;
 540 }
 541
 542 VLIST_TREE(interfaces, avl_strcmp, iface_update_cb, false, false);