git.meshlink.io Git - meshlink/blob - src/discovery.c

   1 /*
   2   discovery.c -- local network discovery
   3   Copyright (C) 2014-2021 Guus Sliepen <guus@meshlink.io>
   4
   5   This program is free software; you can redistribute it and/or modify
   6   it under the terms of the GNU General Public License as published by
   7   the Free Software Foundation; either version 2 of the License, or
   8   (at your option) any later version.
   9
  10   This program is distributed in the hope that it will be useful,
  11   but WITHOUT ANY WARRANTY; without even the implied warranty of
  12   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13   GNU General Public License for more details.
  14
  15   You should have received a copy of the GNU General Public License along
  16   with this program; if not, write to the Free Software Foundation, Inc.,
  17   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18 */
  19
  20 #define __APPLE_USE_RFC_3542
  21 #include "system.h"
  22
  23 #if defined(__APPLE__)
  24 #include <CoreFoundation/CoreFoundation.h>
  25 #include <CoreFoundation/CFArray.h>
  26 #include <CoreFoundation/CFString.h>
  27 #include <SystemConfiguration/SystemConfiguration.h>
  28 #include <net/if.h>
  29 #include <netinet/in.h>
  30 #elif defined(__unix) && !defined(__linux)
  31 #include <net/if.h>
  32 #include <net/route.h>
  33 #include <netinet/in.h>
  34 #elif defined(__linux)
  35 #include <asm/types.h>
  36 #include <net/if.h>
  37 #include <linux/if_link.h>
  38 #include <linux/netlink.h>
  39 #include <linux/rtnetlink.h>
  40 #endif
  41
  42 #include "mdns.h"
  43 #include "meshlink_internal.h"
  44 #include "event.h"
  45 #include "discovery.h"
  46 #include "sockaddr.h"
  47 #include "logger.h"
  48 #include "netutl.h"
  49 #include "node.h"
  50 #include "connection.h"
  51 #include "utils.h"
  52 #include "xalloc.h"
  53
  54 #define MESHLINK_MDNS_SERVICE_TYPE "_%s._tcp"
  55 #define MESHLINK_MDNS_NAME_KEY "name"
  56 #define MESHLINK_MDNS_FINGERPRINT_KEY "fingerprint"
  57
  58 #ifndef MSG_NOSIGNAL
  59 #define MSG_NOSIGNAL 0
  60 #endif
  61
  62 #ifndef IPV6_ADD_MEMBERSHIP
  63 #define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
  64 #endif
  65
  66 #ifndef IPV6_DROP_MEMBERSHIP
  67 #define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
  68 #endif
  69
  70 static const sockaddr_t mdns_address_ipv4 = {
  71         .in.sin_family = AF_INET,
  72         .in.sin_addr.s_addr = 0xfb0000e0,
  73         .in.sin_port = 0xe914,
  74 };
  75
  76 static const sockaddr_t mdns_address_ipv6 = {
  77         .in6.sin6_family = AF_INET6,
  78         .in6.sin6_addr.s6_addr[0x0] = 0xfd,
  79         .in6.sin6_addr.s6_addr[0x1] = 0x02,
  80         .in6.sin6_addr.s6_addr[0xf] = 0xfb,
  81         .in6.sin6_port = 0xe914,
  82 };
  83
  84 typedef struct discovery_address {
  85         int index;
  86         bool up;
  87         sockaddr_t address;
  88 } discovery_address_t;
  89
  90 static int iface_compare(const void *va, const void *vb) {
  91         const int *a = va;
  92         const int *b = vb;
  93         return *a - *b;
  94 }
  95
  96 static int address_compare(const void *va, const void *vb) {
  97         const discovery_address_t *a = va;
  98         const discovery_address_t *b = vb;
  99
 100         if(a->index != b->index) {
 101                 return a->index - b->index;
 102         }
 103
 104         return sockaddrcmp_noport(&a->address, &b->address);
 105 }
 106
 107 static void send_mdns_packet_ipv4(meshlink_handle_t *mesh, int fd, int index, const sockaddr_t *src, const sockaddr_t *dest, void *data, size_t len) {
 108 #ifdef IP_PKTINFO
 109         struct iovec iov  = {
 110                 .iov_base = data,
 111                 .iov_len = len,
 112         };
 113
 114         struct in_pktinfo pkti = {
 115                 .ipi_ifindex = index,
 116                 .ipi_addr = src->in.sin_addr,
 117         };
 118
 119         union {
 120                 char buf[CMSG_SPACE(sizeof(pkti))];
 121                 struct cmsghdr align;
 122         } u;
 123
 124         memset(&u, 0, sizeof(u));
 125
 126         struct msghdr msg = {
 127                 .msg_name = (struct sockaddr *) &dest->sa,
 128                 .msg_namelen = SALEN(dest->sa),
 129                 .msg_iov = &iov,
 130                 .msg_iovlen = 1,
 131                 .msg_control = u.buf,
 132                 .msg_controllen = sizeof(u.buf),
 133         };
 134
 135         struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
 136         cmsg->cmsg_level = IPPROTO_IP;
 137         cmsg->cmsg_type = IP_PKTINFO;
 138         cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
 139         memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
 140
 141         // Send the packet
 142         ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
 143 #else
 144         (void)index;
 145         (void)src;
 146
 147         // Send the packet
 148         ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
 149 #endif
 150
 151         if(result <= 0) {
 152                 logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
 153         }
 154 }
 155
 156 static void send_mdns_packet_ipv6(meshlink_handle_t *mesh, int fd, int index, const sockaddr_t *src, const sockaddr_t *dest, void *data, size_t len) {
 157 #ifdef IPV6_PKTINFO
 158         struct iovec iov  = {
 159                 .iov_base = data,
 160                 .iov_len = len,
 161         };
 162
 163         struct in6_pktinfo pkti = {
 164                 .ipi6_ifindex = index,
 165                 .ipi6_addr = src->in6.sin6_addr,
 166         };
 167
 168         union {
 169                 char buf[CMSG_SPACE(sizeof(pkti))];
 170                 struct cmsghdr align;
 171         } u;
 172
 173         memset(&u, 0, sizeof u);
 174
 175         struct msghdr msg = {
 176                 .msg_name = (struct sockaddr *) &dest->sa,
 177                 .msg_namelen = SALEN(dest->sa),
 178                 .msg_iov = &iov,
 179                 .msg_iovlen = 1,
 180                 .msg_control = u.buf,
 181                 .msg_controllen = CMSG_LEN(sizeof(pkti)),
 182         };
 183
 184         struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
 185         cmsg->cmsg_level = IPPROTO_IPV6;
 186         cmsg->cmsg_type = IPV6_PKTINFO;
 187         cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
 188         memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
 189
 190         // Send the packet
 191         ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
 192 #else
 193         (void)index;
 194         (void)src;
 195
 196         // Send the packet
 197         ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
 198 #endif
 199
 200         if(result <= 0) {
 201                 logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
 202         }
 203 }
 204
 205 static void send_mdns_packet(meshlink_handle_t *mesh, const discovery_address_t *addr) {
 206         // Configure the socket to send the packet to the right interface
 207         int fd;
 208         uint8_t request[1024], response[1024];
 209         char *fingerprint = meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self);
 210         const char *keys[] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
 211         const char *values[] = {mesh->name, fingerprint};
 212         size_t request_size = prepare_request(request, sizeof request, mesh->appname, "tcp");
 213         size_t response_size = prepare_response(response, sizeof response, fingerprint, mesh->appname, "tcp", atoi(mesh->myport), 2, keys, values);
 214         free(fingerprint);
 215
 216         switch(addr->address.sa.sa_family) {
 217         case AF_INET:
 218                 fd = mesh->discovery.sockets[0].fd;
 219 #ifdef IP_MULTICAST_IF
 220                 {
 221                         struct ip_mreqn mreq = {
 222                                 .imr_address = addr->address.in.sin_addr,
 223                                 .imr_ifindex = addr->index,
 224                         };
 225
 226                         if(setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &mreq, sizeof(mreq)) != 0) {
 227                                 logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv4 socket");
 228                                 return;
 229                         }
 230                 }
 231
 232 #endif
 233
 234                 send_mdns_packet_ipv4(mesh, fd, addr->index, &addr->address, &mdns_address_ipv4, request, request_size);
 235                 send_mdns_packet_ipv4(mesh, fd, addr->index, &addr->address, &mdns_address_ipv4, response, response_size);
 236                 break;
 237
 238         case AF_INET6:
 239                 fd = mesh->discovery.sockets[1].fd;
 240 #ifdef IPV6_MULTICAST_IF
 241
 242                 if(setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &addr->index, sizeof(addr->index)) != 0) {
 243                         logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv6 socket");
 244                         return;
 245                 }
 246
 247 #endif
 248
 249                 send_mdns_packet_ipv6(mesh, fd, addr->index, &addr->address, &mdns_address_ipv6, request, request_size);
 250                 send_mdns_packet_ipv6(mesh, fd, addr->index, &addr->address, &mdns_address_ipv6, response, response_size);
 251                 break;
 252
 253         default:
 254                 break;
 255         }
 256 }
 257
 258 static void mdns_io_handler(event_loop_t *loop, void *data, int flags) {
 259         (void)flags;
 260         meshlink_handle_t *mesh = loop->data;
 261         io_t *io = data;
 262         uint8_t buf[1024];
 263         sockaddr_t sa;
 264         socklen_t sl = sizeof(sa);
 265
 266         ssize_t len = recvfrom(io->fd, buf, sizeof(buf), MSG_DONTWAIT, &sa.sa, &sl);
 267
 268         if(len == -1) {
 269                 if(!sockwouldblock(errno)) {
 270                         logger(mesh, MESHLINK_ERROR, "Error reading from mDNS discovery socket: %s", strerror(errno));
 271                         io_set(loop, io, 0);
 272                 }
 273
 274                 return;
 275         }
 276
 277         char *name = NULL;
 278         uint16_t port = 0;
 279         const char *keys[2] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
 280         char *values[2] = {NULL, NULL};
 281
 282         if(parse_response(buf, len, &name, mesh->appname, "tcp", &port, 2, keys, values)) {
 283                 node_t *n = (node_t *)meshlink_get_node(mesh, values[0]);
 284
 285                 if(n) {
 286                         if(n != mesh->self) {
 287                                 logger(mesh, MESHLINK_INFO, "Node %s discovered on the local network.\n", n->name);
 288                         }
 289
 290                         switch(sa.sa.sa_family) {
 291                         case AF_INET:
 292                                 sa.in.sin_port = htons(port);
 293                                 break;
 294
 295                         case AF_INET6:
 296                                 sa.in6.sin6_port = htons(port);
 297                                 break;
 298
 299                         default:
 300                                 logger(mesh, MESHLINK_WARNING, "Could not resolve node %s to a known address family type.\n", n->name);
 301                                 sa.sa.sa_family = AF_UNKNOWN;
 302                                 break;
 303                         }
 304
 305                         if(sa.sa.sa_family != AF_UNKNOWN) {
 306                                 n->catta_address = sa;
 307                                 n->last_connect_try = 0;
 308                                 node_add_recent_address(mesh, n, &sa);
 309
 310                                 if(n->connection) {
 311                                         n->connection->last_ping_time = -3600;
 312                                 }
 313
 314                                 for list_each(outgoing_t, outgoing, mesh->outgoings) {
 315                                         if(outgoing->node != n) {
 316                                                 continue;
 317                                         }
 318
 319                                         outgoing->timeout = 0;
 320
 321                                         if(outgoing->ev.cb) {
 322                                                 timeout_set(&mesh->loop, &outgoing->ev, &(struct timespec) {
 323                                                         0, 0
 324                                                 });
 325                                         }
 326                                 }
 327                         }
 328                 }
 329         } else if(parse_request(buf, len, mesh->appname, "tcp")) {
 330                 // Send a unicast response back
 331                 char *fingerprint = meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self);
 332                 const char *response_values[] = {mesh->name, fingerprint};
 333                 size_t size = prepare_response(buf, sizeof(buf), fingerprint, mesh->appname, "tcp", atoi(mesh->myport), 2, keys, response_values);
 334                 sendto(io->fd, buf, size, MSG_DONTWAIT | MSG_NOSIGNAL, &sa.sa, sl);
 335                 free(fingerprint);
 336         }
 337
 338         free(name);
 339
 340         for(int i = 0; i < 2; i++) {
 341                 free(values[i]);
 342         }
 343 }
 344
 345 static void iface_up(meshlink_handle_t *mesh, int index) {
 346         int *p = bsearch(&index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 347
 348         if(p) {
 349                 return;
 350         }
 351
 352         mesh->discovery.ifaces = xrealloc(mesh->discovery.ifaces, ++mesh->discovery.iface_count * sizeof(*p));
 353         mesh->discovery.ifaces[mesh->discovery.iface_count - 1] = index;
 354         qsort(mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 355
 356         // Add multicast membership
 357         struct ip_mreqn mreq4 = {
 358                 .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
 359                 .imr_ifindex = index,
 360         };
 361         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
 362         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq4, sizeof(mreq4));
 363
 364         struct ipv6_mreq mreq6 = {
 365                 .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
 366                 .ipv6mr_interface = index,
 367         };
 368         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
 369         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6));
 370
 371         // Send an announcement for all addresses associated with this interface
 372         for(int i = 0; i < mesh->discovery.address_count; i++) {
 373                 if(mesh->discovery.addresses[i].index == index) {
 374                         send_mdns_packet(mesh, &mesh->discovery.addresses[i]);
 375                 }
 376         }
 377
 378         handle_network_change(mesh, true);
 379 }
 380
 381 static void iface_down(meshlink_handle_t *mesh, int index) {
 382         int *p = bsearch(&index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 383
 384         if(!p) {
 385                 return;
 386         }
 387
 388         // Drop multicast membership
 389         struct ip_mreqn mreq4 = {
 390                 .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
 391                 .imr_ifindex = index,
 392         };
 393         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
 394
 395         struct ipv6_mreq mreq6 = {
 396                 .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
 397                 .ipv6mr_interface = index,
 398         };
 399         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
 400
 401         memmove(p, p + 1, (mesh->discovery.ifaces + --mesh->discovery.iface_count - p) * sizeof(*p));
 402
 403         handle_network_change(mesh, mesh->discovery.iface_count);
 404 }
 405
 406 static void addr_add(meshlink_handle_t *mesh, const discovery_address_t *addr) {
 407         discovery_address_t *p = bsearch(addr, mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 408
 409         if(p) {
 410                 return;
 411         }
 412
 413         bool up = bsearch(&addr->index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(int), iface_compare);
 414
 415         mesh->discovery.addresses = xrealloc(mesh->discovery.addresses, ++mesh->discovery.address_count * sizeof(*p));
 416         mesh->discovery.addresses[mesh->discovery.address_count - 1] = *addr;
 417         mesh->discovery.addresses[mesh->discovery.address_count - 1].up = up;
 418
 419         if(up) {
 420                 send_mdns_packet(mesh, &mesh->discovery.addresses[mesh->discovery.address_count - 1]);
 421         }
 422
 423         qsort(mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 424 }
 425
 426 static void addr_del(meshlink_handle_t *mesh, const discovery_address_t *addr) {
 427         discovery_address_t *p = bsearch(addr, mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 428
 429         if(!p) {
 430                 return;
 431         }
 432
 433         memmove(p, p + 1, (mesh->discovery.addresses + --mesh->discovery.address_count - p) * sizeof(*p));
 434 }
 435
 436 void scan_ifaddrs(meshlink_handle_t *mesh) {
 437 #ifdef HAVE_GETIFADDRS
 438         struct ifaddrs *ifa = NULL;
 439
 440         if(getifaddrs(&ifa) == -1) {
 441                 logger(mesh, MESHLINK_ERROR, "Could not get list of interface addresses: %s", strerror(errno));
 442                 return;
 443         }
 444
 445         // Check for interfaces being removed
 446         for(int i = 0; i < mesh->discovery.iface_count;) {
 447                 bool found = false;
 448
 449                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 450                         if(!ifap->ifa_name) {
 451                                 continue;
 452                         }
 453
 454                         int index = if_nametoindex(ifap->ifa_name);
 455
 456                         if(mesh->discovery.ifaces[i] == index) {
 457                                 found = true;
 458                                 break;
 459                         }
 460                 }
 461
 462                 if(!found) {
 463                         iface_down(mesh, mesh->discovery.ifaces[i]);
 464                 } else {
 465                         i++;
 466                 }
 467         }
 468
 469         // Check for addresses being removed
 470         for(int i = 0; i < mesh->discovery.address_count;) {
 471                 discovery_address_t *p = &mesh->discovery.addresses[i];
 472                 bool found = false;
 473
 474                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 475                         if(!ifap->ifa_name || !ifap->ifa_addr) {
 476                                 continue;
 477                         }
 478
 479                         int index = if_nametoindex(ifap->ifa_name);
 480
 481                         if(p->index == index && sockaddrcmp_noport(&p->address, (sockaddr_t *)ifap->ifa_addr) == 0) {
 482                                 found = true;
 483                                 break;
 484                         }
 485                 }
 486
 487                 if(!found) {
 488                         (void)addr_del;
 489                         memmove(p, p + 1, (mesh->discovery.addresses + --mesh->discovery.address_count - p) * sizeof(*p));
 490                 } else {
 491                         i++;
 492                 }
 493         }
 494
 495         // Check for interfaces state changes and addresses going up
 496         for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 497                 if(!ifap->ifa_name) {
 498                         continue;
 499                 }
 500
 501                 int index = if_nametoindex(ifap->ifa_name);
 502
 503                 if(ifap->ifa_flags & IFF_UP && ifap->ifa_flags & IFF_MULTICAST && !(ifap->ifa_flags & IFF_LOOPBACK)) {
 504                         iface_up(mesh, index);
 505                 } else {
 506                         iface_down(mesh, index);
 507                 }
 508
 509                 if(!ifap->ifa_addr) {
 510                         continue;
 511                 }
 512
 513                 discovery_address_t addr  = {
 514                         .index = index,
 515                 };
 516
 517                 sockaddr_t *sa = (sockaddr_t *)ifap->ifa_addr;
 518
 519                 if(sa->sa.sa_family == AF_INET) {
 520                         memcpy(&addr.address.in, &sa->in, sizeof(sa->in));
 521                         addr.address.in.sin_port = ntohs(5353);
 522                 } else if(sa->sa.sa_family == AF_INET6) {
 523                         memcpy(&addr.address.in6, &sa->in6, sizeof(sa->in6));
 524                         addr.address.in6.sin6_port = ntohs(5353);
 525                 } else {
 526                         addr.address.sa.sa_family = AF_UNKNOWN;
 527                 }
 528
 529                 if(addr.address.sa.sa_family != AF_UNKNOWN) {
 530                         addr_add(mesh, &addr);
 531                 }
 532         }
 533
 534         freeifaddrs(ifa);
 535 #else
 536         (void)mesh;
 537 #endif
 538 }
 539
 540 #if defined(__linux)
 541 static void netlink_getlink(int fd) {
 542         static const struct {
 543                 struct nlmsghdr nlm;
 544                 struct ifinfomsg ifi;
 545         } msg = {
 546                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifi)),
 547                 .nlm.nlmsg_type = RTM_GETLINK,
 548                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 549                 .nlm.nlmsg_seq = 1,
 550                 .ifi.ifi_family = AF_UNSPEC,
 551         };
 552         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 553 }
 554
 555 static void netlink_getaddr(int fd) {
 556         static const struct {
 557                 struct nlmsghdr nlm;
 558                 struct ifaddrmsg ifa;
 559         } msg = {
 560                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifa)),
 561                 .nlm.nlmsg_type = RTM_GETADDR,
 562                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 563                 .nlm.nlmsg_seq = 2,
 564                 .ifa.ifa_family = AF_UNSPEC,
 565         };
 566         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 567 }
 568
 569 static void netlink_parse_link(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 570         const struct ifinfomsg *ifi = (const struct ifinfomsg *)(nlm + 1);
 571
 572         if(ifi->ifi_flags & IFF_UP && ifi->ifi_flags & IFF_MULTICAST) {
 573                 iface_up(mesh, ifi->ifi_index);
 574         } else {
 575                 iface_down(mesh, ifi->ifi_index);
 576         }
 577 }
 578
 579 static void netlink_parse_addr(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 580         const struct ifaddrmsg *ifa = (const struct ifaddrmsg *)(nlm + 1);
 581         const uint8_t *ptr = (const uint8_t *)(ifa + 1);
 582         size_t len = nlm->nlmsg_len - (ptr - (const uint8_t *)nlm);
 583
 584         while(len >= sizeof(struct rtattr)) {
 585                 const struct rtattr *rta = (const struct rtattr *)ptr;
 586
 587                 if(rta->rta_len <= 0 || rta->rta_len > len) {
 588                         break;
 589                 }
 590
 591                 if(rta->rta_type == IFA_ADDRESS) {
 592                         discovery_address_t addr  = {
 593                                 .index = ifa->ifa_index,
 594                         };
 595
 596                         if(rta->rta_len == 8) {
 597                                 addr.address.sa.sa_family = AF_INET;
 598                                 memcpy(&addr.address.in.sin_addr, ptr + 4, 4);
 599                                 addr.address.in.sin_port = ntohs(5353);
 600                         } else if(rta->rta_len == 20) {
 601                                 addr.address.sa.sa_family = AF_INET6;
 602                                 memcpy(&addr.address.in6.sin6_addr, ptr + 4, 16);
 603                                 addr.address.in6.sin6_port = ntohs(5353);
 604                                 addr.address.in6.sin6_scope_id = ifa->ifa_index;
 605                         } else {
 606                                 addr.address.sa.sa_family = AF_UNKNOWN;
 607                         }
 608
 609                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 610                                 if(nlm->nlmsg_type == RTM_NEWADDR) {
 611                                         addr_add(mesh, &addr);
 612                                 } else {
 613                                         addr_del(mesh, &addr);
 614                                 }
 615                         }
 616                 }
 617
 618                 unsigned short rta_len = (rta->rta_len + 3) & ~3;
 619                 ptr += rta_len;
 620                 len -= rta_len;
 621         }
 622 }
 623
 624 static void netlink_parse(meshlink_handle_t *mesh, const void *data, size_t len) {
 625         const uint8_t *ptr = data;
 626
 627         while(len >= sizeof(struct nlmsghdr)) {
 628                 const struct nlmsghdr *nlm = (const struct nlmsghdr *)ptr;
 629
 630                 if(nlm->nlmsg_len > len) {
 631                         break;
 632                 }
 633
 634                 switch(nlm->nlmsg_type) {
 635                 case RTM_NEWLINK:
 636                 case RTM_DELLINK:
 637                         netlink_parse_link(mesh, nlm);
 638                         break;
 639
 640                 case RTM_NEWADDR:
 641                 case RTM_DELADDR:
 642                         netlink_parse_addr(mesh, nlm);
 643                 }
 644
 645                 ptr += nlm->nlmsg_len;
 646                 len -= nlm->nlmsg_len;
 647         }
 648 }
 649
 650 static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
 651         (void)flags;
 652         (void)data;
 653         meshlink_handle_t *mesh = loop->data;
 654
 655         struct {
 656                 struct nlmsghdr nlm;
 657                 char data[16384];
 658         } msg;
 659
 660         while(true) {
 661                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 662
 663                 if(result <= 0) {
 664                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 665                                 break;
 666                         }
 667
 668                         logger(mesh, MESHLINK_ERROR, "Reading from Netlink socket failed: %s\n", strerror(errno));
 669                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 670                 }
 671
 672                 if((size_t)result < sizeof(msg.nlm)) {
 673                         logger(mesh, MESHLINK_ERROR, "Invalid Netlink message\n");
 674                         break;
 675                 }
 676
 677                 if(msg.nlm.nlmsg_type == NLMSG_DONE) {
 678                         if(msg.nlm.nlmsg_seq == 1) {
 679                                 // We just got the result of GETLINK, now send GETADDR.
 680                                 netlink_getaddr(mesh->discovery.pfroute_io.fd);
 681                         }
 682                 } else {
 683                         netlink_parse(mesh, &msg, result);
 684
 685                         if(loop->now.tv_sec > mesh->discovery.last_update + 5) {
 686                                 mesh->discovery.last_update = loop->now.tv_sec;
 687                                 handle_network_change(mesh, true);
 688                         }
 689                 }
 690         }
 691 }
 692 #elif defined(__APPLE__)
 693 static void reachability_change_callback(SCNetworkReachabilityRef reachability, SCNetworkReachabilityFlags flags, void *info) {
 694         (void)reachability;
 695         (void)flags;
 696
 697         meshlink_handle_t *mesh = info;
 698
 699         pthread_mutex_lock(&mesh->mutex);
 700
 701         scan_ifaddrs(mesh);
 702
 703         if(mesh->loop.now.tv_sec > mesh->discovery.last_update + 5) {
 704                 logger(mesh, MESHLINK_INFO, "Network change detected");
 705                 mesh->discovery.last_update = mesh->loop.now.tv_sec;
 706                 handle_network_change(mesh, true);
 707         }
 708
 709         pthread_mutex_unlock(&mesh->mutex);
 710 }
 711
 712 static void *network_change_handler(void *arg) {
 713         meshlink_handle_t *mesh = arg;
 714
 715         mesh->discovery.runloop = CFRunLoopGetCurrent();
 716
 717         SCNetworkReachabilityRef reach_v4 = SCNetworkReachabilityCreateWithName(NULL, "93.184.216.34");
 718         SCNetworkReachabilityRef reach_v6 = SCNetworkReachabilityCreateWithName(NULL, "2606:2800:220:1:248:1893:25c8:1946");
 719
 720         SCNetworkReachabilityContext context;
 721         memset(&context, 0, sizeof(context));
 722         context.info = mesh;
 723
 724         if(reach_v4) {
 725                 SCNetworkReachabilitySetCallback(reach_v4, reachability_change_callback, &context);
 726                 SCNetworkReachabilityScheduleWithRunLoop(reach_v4, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 727         } else {
 728                 logger(mesh, MESHLINK_ERROR, "Could not create IPv4 network reachability watcher");
 729         }
 730
 731         if(reach_v6) {
 732                 SCNetworkReachabilitySetCallback(reach_v6, reachability_change_callback, &context);
 733                 SCNetworkReachabilityScheduleWithRunLoop(reach_v6, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 734         } else {
 735                 logger(mesh, MESHLINK_ERROR, "Could not create IPv6 network reachability watcher");
 736         }
 737
 738         CFRunLoopRun();
 739
 740         mesh->discovery.runloop = NULL;
 741
 742         if(reach_v4) {
 743                 SCNetworkReachabilityUnscheduleFromRunLoop(reach_v4, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 744                 CFRelease(reach_v4);
 745         }
 746
 747         if(reach_v6) {
 748                 SCNetworkReachabilityUnscheduleFromRunLoop(reach_v6, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 749                 CFRelease(reach_v6);
 750         }
 751
 752         return NULL;
 753 }
 754 #elif defined(RTM_NEWADDR)
 755 static void pfroute_parse_iface(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 756         const struct if_msghdr *ifm = (const struct if_msghdr *)rtm;
 757
 758         if(ifm->ifm_flags & IFF_UP && ifm->ifm_flags & IFF_MULTICAST && !(ifm->ifm_flags & IFF_LOOPBACK)) {
 759                 iface_up(mesh, ifm->ifm_index);
 760         } else {
 761                 iface_down(mesh, ifm->ifm_index);
 762         }
 763 }
 764
 765 static void pfroute_parse_addr(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 766         const struct ifa_msghdr *ifam = (const struct ifa_msghdr *)rtm;
 767         const char *p = (const char *)(ifam + 1);
 768
 769         for(unsigned int i = 1; i; i <<= 1) {
 770                 if(!(ifam->ifam_addrs & i)) {
 771                         continue;
 772                 }
 773
 774                 const sockaddr_t *sa = (const sockaddr_t *)p;
 775
 776                 if(i == RTA_IFA) {
 777                         discovery_address_t addr = {
 778                                 .index = ifam->ifam_index,
 779                         };
 780
 781                         if(sa->sa.sa_family == AF_INET) {
 782                                 addr.address.in = sa->in;
 783                                 addr.address.in.sin_port = ntohs(5353);
 784                         } else if(sa->sa.sa_family == AF_INET6) {
 785                                 addr.address.in6 = sa->in6;
 786                                 addr.address.in6.sin6_port = ntohs(5353);
 787                         } else {
 788                                 addr.address.sa.sa_family = AF_UNKNOWN;
 789                         }
 790
 791                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 792                                 if(ifam->ifam_type == RTM_NEWADDR) {
 793                                         addr_add(mesh, &addr);
 794                                 } else {
 795                                         addr_del(mesh, &addr);
 796                                 }
 797                         }
 798
 799                         break;
 800                 }
 801
 802                 size_t len = (sa->sa.sa_len + 3) & ~3;
 803                 p += len;
 804         }
 805 }
 806
 807 static void pfroute_io_handler(event_loop_t *loop, void *data, int flags) {
 808         (void)flags;
 809         (void)data;
 810         meshlink_handle_t *mesh = loop->data;
 811
 812         struct {
 813                 struct rt_msghdr rtm;
 814                 char data[2048];
 815         } msg;
 816
 817         while(true) {
 818                 msg.rtm.rtm_version = 0;
 819                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 820
 821                 if(result <= 0) {
 822                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 823                                 break;
 824                         }
 825
 826                         logger(mesh, MESHLINK_ERROR, "Reading from PFROUTE socket failed: %s\n", strerror(errno));
 827                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 828                 }
 829
 830                 if(msg.rtm.rtm_version != RTM_VERSION) {
 831                         logger(mesh, MESHLINK_ERROR, "Invalid PFROUTE message version\n");
 832                         break;
 833                 }
 834
 835                 switch(msg.rtm.rtm_type) {
 836                 case RTM_IFINFO:
 837                         pfroute_parse_iface(mesh, &msg.rtm);
 838                         break;
 839
 840                 case RTM_NEWADDR:
 841                 case RTM_DELADDR:
 842                         pfroute_parse_addr(mesh, &msg.rtm);
 843                         break;
 844
 845                 default:
 846                         break;
 847                 }
 848         }
 849 }
 850 #endif
 851
 852 bool discovery_start(meshlink_handle_t *mesh) {
 853         logger(mesh, MESHLINK_DEBUG, "discovery_start called\n");
 854
 855         assert(mesh);
 856
 857         // Set up multicast sockets for mDNS
 858         static const int one = 1;
 859         static const int ttl = 255;
 860         static const uint8_t one8 = 1;
 861         static const uint8_t ttl8 = 255;
 862
 863         int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 864
 865         if(fd == -1) {
 866                 logger(mesh, MESHLINK_ERROR, "Error creating IPv4 socket: %s", strerror(errno));
 867         }
 868
 869         sockaddr_t sa4 = {
 870                 .in.sin_family = AF_INET,
 871                 .in.sin_port = ntohs(5353),
 872         };
 873         setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 874 #ifdef SO_REUSEPORT
 875         setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 876 #endif
 877         setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one8, sizeof(one8));
 878         setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl8, sizeof(ttl8));
 879
 880         if(bind(fd, &sa4.sa, SALEN(sa4.sa)) == -1) {
 881                 logger(mesh, MESHLINK_ERROR, "Error binding to IPv4 multicast socket: %s", strerror(errno));
 882         } else {
 883                 io_add(&mesh->loop, &mesh->discovery.sockets[0], mdns_io_handler, &mesh->discovery.sockets[0], fd, IO_READ);
 884         }
 885
 886         sockaddr_t sa6 = {
 887                 .in6.sin6_family = AF_INET6,
 888                 .in6.sin6_port = ntohs(5353),
 889         };
 890         fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
 891
 892         if(fd == -1) {
 893                 logger(mesh, MESHLINK_ERROR, "Error creating IPv6 socket: %s", strerror(errno));
 894         }
 895
 896         setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 897 #ifdef SO_REUSEPORT
 898         setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 899 #endif
 900         setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
 901         setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
 902         setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
 903         setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
 904
 905         if(bind(fd, &sa6.sa, SALEN(sa6.sa)) == -1) {
 906                 logger(mesh, MESHLINK_ERROR, "Error binding to IPv4 multicast socket: %s", strerror(errno));
 907         } else {
 908                 io_add(&mesh->loop, &mesh->discovery.sockets[1], mdns_io_handler, &mesh->discovery.sockets[1], fd, IO_READ);
 909         }
 910
 911 #if defined(__linux)
 912         int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
 913
 914         if(sock != -1) {
 915                 struct sockaddr_nl sa;
 916                 memset(&sa, 0, sizeof(sa));
 917                 sa.nl_family = AF_NETLINK;
 918                 sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;
 919
 920                 if(bind(sock, (struct sockaddr *)&sa, sizeof(sa)) != -1) {
 921                         io_add(&mesh->loop, &mesh->discovery.pfroute_io, netlink_io_handler, NULL, sock, IO_READ);
 922                         netlink_getlink(sock);
 923                 } else {
 924                         logger(mesh, MESHLINK_WARNING, "Could not bind AF_NETLINK socket: %s", strerror(errno));
 925                         scan_ifaddrs(mesh);
 926                 }
 927         } else {
 928                 logger(mesh, MESHLINK_WARNING, "Could not open AF_NETLINK socket: %s", strerror(errno));
 929                 scan_ifaddrs(mesh);
 930         }
 931
 932 #elif defined(__APPLE__)
 933         pthread_create(&mesh->discovery.thread, NULL, network_change_handler, mesh);
 934         // TODO: Do we need to wait for the thread to start succesfully?
 935         scan_ifaddrs(mesh);
 936 #elif defined(RTM_NEWADDR)
 937         int sock = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC);
 938
 939         if(sock != -1) {
 940                 io_add(&mesh->loop, &mesh->discovery.pfroute_io, pfroute_io_handler, NULL, sock, IO_READ);
 941         } else {
 942                 logger(mesh, MESHLINK_WARNING, "Could not open PF_ROUTE socket: %s", strerror(errno));
 943         }
 944
 945         scan_ifaddrs(mesh);
 946 #endif
 947
 948         return true;
 949 }
 950
 951 void discovery_stop(meshlink_handle_t *mesh) {
 952         logger(mesh, MESHLINK_DEBUG, "discovery_stop called\n");
 953
 954         assert(mesh);
 955
 956         free(mesh->discovery.ifaces);
 957         free(mesh->discovery.addresses);
 958         mesh->discovery.ifaces = NULL;
 959         mesh->discovery.addresses = NULL;
 960         mesh->discovery.iface_count = 0;
 961         mesh->discovery.address_count = 0;
 962
 963 #if defined(__APPLE__)
 964
 965         if(mesh->discovery.runloop) {
 966                 CFRunLoopStop(mesh->discovery.runloop);
 967                 pthread_join(mesh->discovery.thread, NULL);
 968         }
 969
 970 #endif
 971
 972         if(mesh->discovery.pfroute_io.cb) {
 973                 close(mesh->discovery.pfroute_io.fd);
 974                 io_del(&mesh->loop, &mesh->discovery.pfroute_io);
 975         }
 976
 977         for(int i = 0; i < 2; i++) {
 978                 if(mesh->discovery.sockets[i].cb) {
 979                         close(mesh->discovery.sockets[i].fd);
 980                         io_del(&mesh->loop, &mesh->discovery.sockets[i]);
 981                 }
 982         }
 983 }
 984
 985 void discovery_refresh(meshlink_handle_t *mesh) {
 986         for(int i = 0; i < mesh->discovery.address_count; i++) {
 987                 if(mesh->discovery.addresses[i].up) {
 988                         send_mdns_packet(mesh, &mesh->discovery.addresses[i]);
 989                 }
 990         }
 991 }