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] = 0xff,
  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         time_t last_response_sent;
  89 } discovery_address_t;
  90
  91 static int iface_compare(const void *va, const void *vb) {
  92         const int *a = va;
  93         const int *b = vb;
  94         return *a - *b;
  95 }
  96
  97 static int address_compare(const void *va, const void *vb) {
  98         const discovery_address_t *a = va;
  99         const discovery_address_t *b = vb;
 100
 101         if(a->index != b->index) {
 102                 return a->index - b->index;
 103         }
 104
 105         return sockaddrcmp_noport(&a->address, &b->address);
 106 }
 107
 108 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) {
 109 #ifdef IP_MULTICAST_IF
 110         struct ip_mreqn mreq = {
 111                 .imr_address = src->in.sin_addr,
 112                 .imr_ifindex = index,
 113         };
 114
 115         if(setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &mreq, sizeof(mreq)) != 0) {
 116                 logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv4 socket");
 117                 return;
 118         }
 119
 120 #endif
 121
 122 #ifdef IP_PKTINFO
 123         struct iovec iov  = {
 124                 .iov_base = data,
 125                 .iov_len = len,
 126         };
 127
 128         struct in_pktinfo pkti = {
 129                 .ipi_ifindex = index,
 130                 .ipi_addr = src->in.sin_addr,
 131         };
 132
 133         union {
 134                 char buf[CMSG_SPACE(sizeof(pkti))];
 135                 struct cmsghdr align;
 136         } u;
 137
 138         memset(&u, 0, sizeof(u));
 139
 140         struct msghdr msg = {
 141                 .msg_name = (struct sockaddr *) &dest->sa,
 142                 .msg_namelen = SALEN(dest->sa),
 143                 .msg_iov = &iov,
 144                 .msg_iovlen = 1,
 145                 .msg_control = u.buf,
 146                 .msg_controllen = sizeof(u.buf),
 147         };
 148
 149         struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
 150         cmsg->cmsg_level = IPPROTO_IP;
 151         cmsg->cmsg_type = IP_PKTINFO;
 152         cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
 153         memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
 154
 155         // Send the packet
 156         ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
 157 #else
 158         (void)index;
 159         (void)src;
 160
 161         // Send the packet
 162         ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
 163 #endif
 164
 165         if(result <= 0) {
 166                 logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
 167         }
 168 }
 169
 170 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) {
 171 #ifdef IPV6_MULTICAST_IF
 172
 173         if(setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &index, sizeof(index)) != 0) {
 174                 logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv6 socket");
 175                 return;
 176         }
 177
 178 #endif
 179
 180 #ifdef IPV6_PKTINFO
 181         struct iovec iov  = {
 182                 .iov_base = data,
 183                 .iov_len = len,
 184         };
 185
 186         struct in6_pktinfo pkti = {
 187                 .ipi6_ifindex = index,
 188                 .ipi6_addr = src->in6.sin6_addr,
 189         };
 190
 191         union {
 192                 char buf[CMSG_SPACE(sizeof(pkti))];
 193                 struct cmsghdr align;
 194         } u;
 195
 196         memset(&u, 0, sizeof u);
 197
 198         struct msghdr msg = {
 199                 .msg_name = (struct sockaddr *) &dest->sa,
 200                 .msg_namelen = SALEN(dest->sa),
 201                 .msg_iov = &iov,
 202                 .msg_iovlen = 1,
 203                 .msg_control = u.buf,
 204                 .msg_controllen = CMSG_LEN(sizeof(pkti)),
 205         };
 206
 207         struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
 208         cmsg->cmsg_level = IPPROTO_IPV6;
 209         cmsg->cmsg_type = IPV6_PKTINFO;
 210         cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
 211         memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
 212
 213         // Send the packet
 214         ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
 215 #else
 216         (void)index;
 217         (void)src;
 218
 219         // Send the packet
 220         ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
 221 #endif
 222
 223         if(result <= 0) {
 224                 logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
 225         }
 226 }
 227
 228 static void send_mdns_packet(meshlink_handle_t *mesh, discovery_address_t *addr, bool response) {
 229         // Configure the socket to send the packet to the right interface
 230         uint8_t msg[1024];
 231         size_t msg_size;
 232
 233         if(response) {
 234                 char *fingerprint = meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self);
 235                 static const char *keys[] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
 236                 const char *values[] = {mesh->name, fingerprint};
 237                 msg_size = prepare_response(msg, sizeof msg, fingerprint, mesh->appname, "tcp", atoi(mesh->myport), 2, keys, values);
 238                 free(fingerprint);
 239                 addr->last_response_sent = mesh->loop.now.tv_sec;
 240         } else {
 241                 msg_size = prepare_request(msg, sizeof msg, mesh->appname, "tcp");
 242         }
 243
 244         switch(addr->address.sa.sa_family) {
 245         case AF_INET:
 246                 send_mdns_packet_ipv4(mesh, mesh->discovery.sockets[0].fd, addr->index, &addr->address, &mdns_address_ipv4, msg, msg_size);
 247                 break;
 248
 249         case AF_INET6:
 250                 send_mdns_packet_ipv6(mesh, mesh->discovery.sockets[1].fd, addr->index, &addr->address, &mdns_address_ipv6, msg, msg_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 #ifdef IP_PKTINFO
 267         struct iovec iov  = {
 268                 .iov_base = buf,
 269                 .iov_len = sizeof(buf),
 270         };
 271
 272         union {
 273                 char buf[1024];
 274                 struct cmsghdr align;
 275         } u;
 276
 277         struct msghdr msg = {
 278                 .msg_name = &sa,
 279                 .msg_namelen = sl,
 280                 .msg_iov = &iov,
 281                 .msg_iovlen = 1,
 282                 .msg_control = u.buf,
 283                 .msg_controllen = sizeof(u.buf),
 284         };
 285
 286         ssize_t len = recvmsg(io->fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
 287
 288         sl = msg.msg_namelen;
 289 #else
 290         ssize_t len = recvfrom(io->fd, buf, sizeof(buf), MSG_DONTWAIT, &sa.sa, &sl);
 291 #endif
 292
 293         if(len == -1) {
 294                 if(!sockwouldblock(errno)) {
 295                         logger(mesh, MESHLINK_ERROR, "Error reading from mDNS discovery socket: %s", strerror(errno));
 296                         io_set(loop, io, 0);
 297                 }
 298
 299                 return;
 300         }
 301
 302         char *name = NULL;
 303         uint16_t port = 0;
 304         const char *keys[2] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
 305         char *values[2] = {NULL, NULL};
 306
 307         if(parse_response(buf, len, &name, mesh->appname, "tcp", &port, 2, keys, values)) {
 308                 node_t *n = (node_t *)meshlink_get_node(mesh, values[0]);
 309
 310                 if(n) {
 311                         if(n != mesh->self) {
 312                                 logger(mesh, MESHLINK_INFO, "Node %s discovered on the local network.\n", n->name);
 313                         }
 314
 315                         switch(sa.sa.sa_family) {
 316                         case AF_INET:
 317                                 sa.in.sin_port = htons(port);
 318                                 break;
 319
 320                         case AF_INET6:
 321                                 sa.in6.sin6_port = htons(port);
 322                                 break;
 323
 324                         default:
 325                                 logger(mesh, MESHLINK_WARNING, "Could not resolve node %s to a known address family type.\n", n->name);
 326                                 sa.sa.sa_family = AF_UNKNOWN;
 327                                 break;
 328                         }
 329
 330                         if(sa.sa.sa_family != AF_UNKNOWN) {
 331                                 n->catta_address = sa;
 332                                 n->last_connect_try = 0;
 333                                 node_add_recent_address(mesh, n, &sa);
 334
 335                                 if(n->connection) {
 336                                         n->connection->last_ping_time = -3600;
 337                                 }
 338
 339                                 for list_each(outgoing_t, outgoing, mesh->outgoings) {
 340                                         if(outgoing->node != n) {
 341                                                 continue;
 342                                         }
 343
 344                                         outgoing->timeout = 0;
 345
 346                                         if(outgoing->ev.cb) {
 347                                                 timeout_set(&mesh->loop, &outgoing->ev, &(struct timespec) {
 348                                                         0, 0
 349                                                 });
 350                                         }
 351                                 }
 352                         }
 353                 }
 354         } else if(parse_request(buf, len, mesh->appname, "tcp")) {
 355                 char *fingerprint = meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self);
 356                 const char *response_values[] = {mesh->name, fingerprint};
 357                 size_t size = prepare_response(buf, sizeof(buf), fingerprint, mesh->appname, "tcp", atoi(mesh->myport), 2, keys, response_values);
 358
 359                 int index = -1;
 360                 int family = AF_UNSPEC;
 361
 362                 for(struct cmsghdr *cmptr = CMSG_FIRSTHDR(&msg); cmptr != NULL; cmptr = CMSG_NXTHDR(&msg, cmptr)) {
 363 #ifdef IP_PKTINFO
 364
 365                         if(cmptr->cmsg_level == IPPROTO_IP && cmptr->cmsg_type == IP_PKTINFO) {
 366                                 struct in_pktinfo *pktinfo = (struct in_pktinfo *) CMSG_DATA(cmptr);
 367                                 index = pktinfo->ipi_ifindex;
 368                                 family = AF_INET;
 369                                 break;
 370                         } else
 371 #endif
 372 #ifdef IPV6_PKTINFO
 373                                 if(cmptr->cmsg_level == IPPROTO_IPV6 && cmptr->cmsg_type == IPV6_PKTINFO) {
 374                                         struct in6_pktinfo *pktinfo = (struct in6_pktinfo *) CMSG_DATA(cmptr);
 375                                         index = pktinfo->ipi6_ifindex;
 376                                         family = AF_INET6;
 377                                         break;
 378                                 }
 379
 380 #endif
 381                 }
 382
 383                 if(index) {
 384                         // Send a multicast response back using all addresses matching the interface
 385                         for(int i = 0; i < mesh->discovery.address_count; i++) {
 386                                 discovery_address_t *p = &mesh->discovery.addresses[i];
 387
 388                                 if(p->index == index && p->address.sa.sa_family == family) {
 389                                         send_mdns_packet(mesh, p, true);
 390                                 }
 391                         }
 392                 } else {
 393                         // Send a unicast response back
 394                         sendto(io->fd, buf, size, MSG_DONTWAIT | MSG_NOSIGNAL, &sa.sa, sl);
 395                 }
 396
 397                 free(fingerprint);
 398         }
 399
 400         free(name);
 401
 402         for(int i = 0; i < 2; i++) {
 403                 free(values[i]);
 404         }
 405 }
 406
 407 static void iface_up(meshlink_handle_t *mesh, int index) {
 408         int *p = bsearch(&index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 409
 410         if(p) {
 411                 return;
 412         }
 413
 414         mesh->discovery.ifaces = xrealloc(mesh->discovery.ifaces, ++mesh->discovery.iface_count * sizeof(*p));
 415         mesh->discovery.ifaces[mesh->discovery.iface_count - 1] = index;
 416         qsort(mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 417
 418         // Add multicast membership
 419         struct ip_mreqn mreq4 = {
 420                 .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
 421                 .imr_ifindex = index,
 422         };
 423
 424         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
 425         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq4, sizeof(mreq4));
 426
 427         struct ipv6_mreq mreq6 = {
 428                 .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
 429                 .ipv6mr_interface = index,
 430         };
 431
 432         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
 433         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6));
 434
 435         // Send an announcement for all addresses associated with this interface
 436         for(int i = 0; i < mesh->discovery.address_count; i++) {
 437                 if(mesh->discovery.addresses[i].index == index) {
 438                         send_mdns_packet(mesh, &mesh->discovery.addresses[i], false);
 439                 }
 440         }
 441
 442         handle_network_change(mesh, true);
 443 }
 444
 445 static void iface_down(meshlink_handle_t *mesh, int index) {
 446         int *p = bsearch(&index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 447
 448         if(!p) {
 449                 return;
 450         }
 451
 452         // Drop multicast membership
 453         struct ip_mreqn mreq4 = {
 454                 .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
 455                 .imr_ifindex = index,
 456         };
 457         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
 458
 459         struct ipv6_mreq mreq6 = {
 460                 .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
 461                 .ipv6mr_interface = index,
 462         };
 463         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
 464
 465         memmove(p, p + 1, (mesh->discovery.ifaces + --mesh->discovery.iface_count - p) * sizeof(*p));
 466
 467         handle_network_change(mesh, mesh->discovery.iface_count);
 468 }
 469
 470 static void addr_add(meshlink_handle_t *mesh, const discovery_address_t *addr) {
 471         discovery_address_t *p = bsearch(addr, mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 472
 473         if(p) {
 474                 return;
 475         }
 476
 477         bool up = bsearch(&addr->index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(int), iface_compare);
 478
 479         mesh->discovery.addresses = xrealloc(mesh->discovery.addresses, ++mesh->discovery.address_count * sizeof(*p));
 480         mesh->discovery.addresses[mesh->discovery.address_count - 1] = *addr;
 481         mesh->discovery.addresses[mesh->discovery.address_count - 1].up = up;
 482
 483         if(up) {
 484                 send_mdns_packet(mesh, &mesh->discovery.addresses[mesh->discovery.address_count - 1], false);
 485         }
 486
 487         qsort(mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 488 }
 489
 490 static void addr_del(meshlink_handle_t *mesh, const discovery_address_t *addr) {
 491         discovery_address_t *p = bsearch(addr, mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 492
 493         if(!p) {
 494                 return;
 495         }
 496
 497         memmove(p, p + 1, (mesh->discovery.addresses + --mesh->discovery.address_count - p) * sizeof(*p));
 498 }
 499
 500 void scan_ifaddrs(meshlink_handle_t *mesh) {
 501 #ifdef HAVE_GETIFADDRS
 502         struct ifaddrs *ifa = NULL;
 503
 504         if(getifaddrs(&ifa) == -1) {
 505                 logger(mesh, MESHLINK_ERROR, "Could not get list of interface addresses: %s", strerror(errno));
 506                 return;
 507         }
 508
 509         // Check for interfaces being removed
 510         for(int i = 0; i < mesh->discovery.iface_count;) {
 511                 bool found = false;
 512
 513                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 514                         if(!ifap->ifa_name) {
 515                                 continue;
 516                         }
 517
 518                         int index = if_nametoindex(ifap->ifa_name);
 519
 520                         if(mesh->discovery.ifaces[i] == index) {
 521                                 found = true;
 522                                 break;
 523                         }
 524                 }
 525
 526                 if(!found) {
 527                         iface_down(mesh, mesh->discovery.ifaces[i]);
 528                 } else {
 529                         i++;
 530                 }
 531         }
 532
 533         // Check for addresses being removed
 534         for(int i = 0; i < mesh->discovery.address_count;) {
 535                 discovery_address_t *p = &mesh->discovery.addresses[i];
 536                 bool found = false;
 537
 538                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 539                         if(!ifap->ifa_name || !ifap->ifa_addr) {
 540                                 continue;
 541                         }
 542
 543                         int index = if_nametoindex(ifap->ifa_name);
 544
 545                         if(p->index == index && sockaddrcmp_noport(&p->address, (sockaddr_t *)ifap->ifa_addr) == 0) {
 546                                 found = true;
 547                                 break;
 548                         }
 549                 }
 550
 551                 if(!found) {
 552                         (void)addr_del;
 553                         memmove(p, p + 1, (mesh->discovery.addresses + --mesh->discovery.address_count - p) * sizeof(*p));
 554                 } else {
 555                         i++;
 556                 }
 557         }
 558
 559         // Check for interfaces state changes and addresses going up
 560         for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 561                 if(!ifap->ifa_name) {
 562                         continue;
 563                 }
 564
 565                 int index = if_nametoindex(ifap->ifa_name);
 566
 567                 if(ifap->ifa_flags & IFF_UP && ifap->ifa_flags & IFF_MULTICAST && !(ifap->ifa_flags & IFF_LOOPBACK)) {
 568                         iface_up(mesh, index);
 569                 } else {
 570                         iface_down(mesh, index);
 571                 }
 572
 573                 if(!ifap->ifa_addr) {
 574                         continue;
 575                 }
 576
 577                 discovery_address_t addr  = {
 578                         .index = index,
 579                 };
 580
 581                 sockaddr_t *sa = (sockaddr_t *)ifap->ifa_addr;
 582
 583                 if(sa->sa.sa_family == AF_INET) {
 584                         memcpy(&addr.address.in, &sa->in, sizeof(sa->in));
 585                         addr.address.in.sin_port = ntohs(5353);
 586                 } else if(sa->sa.sa_family == AF_INET6) {
 587                         memcpy(&addr.address.in6, &sa->in6, sizeof(sa->in6));
 588                         addr.address.in6.sin6_port = ntohs(5353);
 589                 } else {
 590                         addr.address.sa.sa_family = AF_UNKNOWN;
 591                 }
 592
 593                 if(addr.address.sa.sa_family != AF_UNKNOWN) {
 594                         addr_add(mesh, &addr);
 595                 }
 596         }
 597
 598         freeifaddrs(ifa);
 599 #else
 600         (void)mesh;
 601 #endif
 602 }
 603
 604 #if defined(__linux)
 605 static void netlink_getlink(int fd) {
 606         static const struct {
 607                 struct nlmsghdr nlm;
 608                 struct ifinfomsg ifi;
 609         } msg = {
 610                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifi)),
 611                 .nlm.nlmsg_type = RTM_GETLINK,
 612                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 613                 .nlm.nlmsg_seq = 1,
 614                 .ifi.ifi_family = AF_UNSPEC,
 615         };
 616         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 617 }
 618
 619 static void netlink_getaddr(int fd) {
 620         static const struct {
 621                 struct nlmsghdr nlm;
 622                 struct ifaddrmsg ifa;
 623         } msg = {
 624                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifa)),
 625                 .nlm.nlmsg_type = RTM_GETADDR,
 626                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 627                 .nlm.nlmsg_seq = 2,
 628                 .ifa.ifa_family = AF_UNSPEC,
 629         };
 630         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 631 }
 632
 633 static void netlink_parse_link(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 634         const struct ifinfomsg *ifi = (const struct ifinfomsg *)(nlm + 1);
 635
 636         if(ifi->ifi_flags & IFF_UP && ifi->ifi_flags & IFF_MULTICAST) {
 637                 iface_up(mesh, ifi->ifi_index);
 638         } else {
 639                 iface_down(mesh, ifi->ifi_index);
 640         }
 641 }
 642
 643 static void netlink_parse_addr(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 644         const struct ifaddrmsg *ifa = (const struct ifaddrmsg *)(nlm + 1);
 645         const uint8_t *ptr = (const uint8_t *)(ifa + 1);
 646         size_t len = nlm->nlmsg_len - (ptr - (const uint8_t *)nlm);
 647
 648         while(len >= sizeof(struct rtattr)) {
 649                 const struct rtattr *rta = (const struct rtattr *)ptr;
 650
 651                 if(rta->rta_len <= 0 || rta->rta_len > len) {
 652                         break;
 653                 }
 654
 655                 if(rta->rta_type == IFA_ADDRESS) {
 656                         discovery_address_t addr  = {
 657                                 .index = ifa->ifa_index,
 658                         };
 659
 660                         if(rta->rta_len == 8) {
 661                                 addr.address.sa.sa_family = AF_INET;
 662                                 memcpy(&addr.address.in.sin_addr, ptr + 4, 4);
 663                                 addr.address.in.sin_port = ntohs(5353);
 664                         } else if(rta->rta_len == 20) {
 665                                 addr.address.sa.sa_family = AF_INET6;
 666                                 memcpy(&addr.address.in6.sin6_addr, ptr + 4, 16);
 667                                 addr.address.in6.sin6_port = ntohs(5353);
 668                                 addr.address.in6.sin6_scope_id = ifa->ifa_index;
 669                         } else {
 670                                 addr.address.sa.sa_family = AF_UNKNOWN;
 671                         }
 672
 673                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 674                                 if(nlm->nlmsg_type == RTM_NEWADDR) {
 675                                         addr_add(mesh, &addr);
 676                                 } else {
 677                                         addr_del(mesh, &addr);
 678                                 }
 679                         }
 680                 }
 681
 682                 unsigned short rta_len = (rta->rta_len + 3) & ~3;
 683                 ptr += rta_len;
 684                 len -= rta_len;
 685         }
 686 }
 687
 688 static void netlink_parse(meshlink_handle_t *mesh, const void *data, size_t len) {
 689         const uint8_t *ptr = data;
 690
 691         while(len >= sizeof(struct nlmsghdr)) {
 692                 const struct nlmsghdr *nlm = (const struct nlmsghdr *)ptr;
 693
 694                 if(nlm->nlmsg_len > len) {
 695                         break;
 696                 }
 697
 698                 switch(nlm->nlmsg_type) {
 699                 case RTM_NEWLINK:
 700                 case RTM_DELLINK:
 701                         netlink_parse_link(mesh, nlm);
 702                         break;
 703
 704                 case RTM_NEWADDR:
 705                 case RTM_DELADDR:
 706                         netlink_parse_addr(mesh, nlm);
 707                 }
 708
 709                 ptr += nlm->nlmsg_len;
 710                 len -= nlm->nlmsg_len;
 711         }
 712 }
 713
 714 static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
 715         (void)flags;
 716         (void)data;
 717         meshlink_handle_t *mesh = loop->data;
 718
 719         struct {
 720                 struct nlmsghdr nlm;
 721                 char data[16384];
 722         } msg;
 723
 724         while(true) {
 725                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 726
 727                 if(result <= 0) {
 728                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 729                                 break;
 730                         }
 731
 732                         logger(mesh, MESHLINK_ERROR, "Reading from Netlink socket failed: %s\n", strerror(errno));
 733                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 734                 }
 735
 736                 if((size_t)result < sizeof(msg.nlm)) {
 737                         logger(mesh, MESHLINK_ERROR, "Invalid Netlink message\n");
 738                         break;
 739                 }
 740
 741                 if(msg.nlm.nlmsg_type == NLMSG_DONE) {
 742                         if(msg.nlm.nlmsg_seq == 1) {
 743                                 // We just got the result of GETLINK, now send GETADDR.
 744                                 netlink_getaddr(mesh->discovery.pfroute_io.fd);
 745                         }
 746                 } else {
 747                         netlink_parse(mesh, &msg, result);
 748
 749                         if(loop->now.tv_sec > mesh->discovery.last_update + 5) {
 750                                 mesh->discovery.last_update = loop->now.tv_sec;
 751                                 handle_network_change(mesh, true);
 752                         }
 753                 }
 754         }
 755 }
 756 #elif defined(__APPLE__)
 757 static void reachability_change_callback(SCNetworkReachabilityRef reachability, SCNetworkReachabilityFlags flags, void *info) {
 758         (void)reachability;
 759         (void)flags;
 760
 761         meshlink_handle_t *mesh = info;
 762
 763         pthread_mutex_lock(&mesh->mutex);
 764
 765         scan_ifaddrs(mesh);
 766
 767         if(mesh->loop.now.tv_sec > mesh->discovery.last_update + 5) {
 768                 logger(mesh, MESHLINK_INFO, "Network change detected");
 769                 mesh->discovery.last_update = mesh->loop.now.tv_sec;
 770                 handle_network_change(mesh, true);
 771         }
 772
 773         pthread_mutex_unlock(&mesh->mutex);
 774 }
 775
 776 static void *network_change_handler(void *arg) {
 777         meshlink_handle_t *mesh = arg;
 778
 779         mesh->discovery.runloop = CFRunLoopGetCurrent();
 780
 781         SCNetworkReachabilityRef reach_v4 = SCNetworkReachabilityCreateWithName(NULL, "93.184.216.34");
 782         SCNetworkReachabilityRef reach_v6 = SCNetworkReachabilityCreateWithName(NULL, "2606:2800:220:1:248:1893:25c8:1946");
 783
 784         SCNetworkReachabilityContext context;
 785         memset(&context, 0, sizeof(context));
 786         context.info = mesh;
 787
 788         if(reach_v4) {
 789                 SCNetworkReachabilitySetCallback(reach_v4, reachability_change_callback, &context);
 790                 SCNetworkReachabilityScheduleWithRunLoop(reach_v4, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 791         } else {
 792                 logger(mesh, MESHLINK_ERROR, "Could not create IPv4 network reachability watcher");
 793         }
 794
 795         if(reach_v6) {
 796                 SCNetworkReachabilitySetCallback(reach_v6, reachability_change_callback, &context);
 797                 SCNetworkReachabilityScheduleWithRunLoop(reach_v6, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 798         } else {
 799                 logger(mesh, MESHLINK_ERROR, "Could not create IPv6 network reachability watcher");
 800         }
 801
 802         CFRunLoopRun();
 803
 804         mesh->discovery.runloop = NULL;
 805
 806         if(reach_v4) {
 807                 SCNetworkReachabilityUnscheduleFromRunLoop(reach_v4, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 808                 CFRelease(reach_v4);
 809         }
 810
 811         if(reach_v6) {
 812                 SCNetworkReachabilityUnscheduleFromRunLoop(reach_v6, mesh->discovery.runloop, kCFRunLoopDefaultMode);
 813                 CFRelease(reach_v6);
 814         }
 815
 816         return NULL;
 817 }
 818 #elif defined(RTM_NEWADDR)
 819 static void pfroute_parse_iface(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 820         const struct if_msghdr *ifm = (const struct if_msghdr *)rtm;
 821
 822         if(ifm->ifm_flags & IFF_UP && ifm->ifm_flags & IFF_MULTICAST && !(ifm->ifm_flags & IFF_LOOPBACK)) {
 823                 iface_up(mesh, ifm->ifm_index);
 824         } else {
 825                 iface_down(mesh, ifm->ifm_index);
 826         }
 827 }
 828
 829 static void pfroute_parse_addr(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 830         const struct ifa_msghdr *ifam = (const struct ifa_msghdr *)rtm;
 831         const char *p = (const char *)(ifam + 1);
 832
 833         for(unsigned int i = 1; i; i <<= 1) {
 834                 if(!(ifam->ifam_addrs & i)) {
 835                         continue;
 836                 }
 837
 838                 const sockaddr_t *sa = (const sockaddr_t *)p;
 839
 840                 if(i == RTA_IFA) {
 841                         discovery_address_t addr = {
 842                                 .index = ifam->ifam_index,
 843                         };
 844
 845                         if(sa->sa.sa_family == AF_INET) {
 846                                 addr.address.in = sa->in;
 847                                 addr.address.in.sin_port = ntohs(5353);
 848                         } else if(sa->sa.sa_family == AF_INET6) {
 849                                 addr.address.in6 = sa->in6;
 850                                 addr.address.in6.sin6_port = ntohs(5353);
 851                         } else {
 852                                 addr.address.sa.sa_family = AF_UNKNOWN;
 853                         }
 854
 855                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 856                                 if(ifam->ifam_type == RTM_NEWADDR) {
 857                                         addr_add(mesh, &addr);
 858                                 } else {
 859                                         addr_del(mesh, &addr);
 860                                 }
 861                         }
 862
 863                         break;
 864                 }
 865
 866                 size_t len = (sa->sa.sa_len + 3) & ~3;
 867                 p += len;
 868         }
 869 }
 870
 871 static void pfroute_io_handler(event_loop_t *loop, void *data, int flags) {
 872         (void)flags;
 873         (void)data;
 874         meshlink_handle_t *mesh = loop->data;
 875
 876         struct {
 877                 struct rt_msghdr rtm;
 878                 char data[2048];
 879         } msg;
 880
 881         while(true) {
 882                 msg.rtm.rtm_version = 0;
 883                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 884
 885                 if(result <= 0) {
 886                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 887                                 break;
 888                         }
 889
 890                         logger(mesh, MESHLINK_ERROR, "Reading from PFROUTE socket failed: %s\n", strerror(errno));
 891                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 892                 }
 893
 894                 if(msg.rtm.rtm_version != RTM_VERSION) {
 895                         logger(mesh, MESHLINK_ERROR, "Invalid PFROUTE message version\n");
 896                         break;
 897                 }
 898
 899                 switch(msg.rtm.rtm_type) {
 900                 case RTM_IFINFO:
 901                         pfroute_parse_iface(mesh, &msg.rtm);
 902                         break;
 903
 904                 case RTM_NEWADDR:
 905                 case RTM_DELADDR:
 906                         pfroute_parse_addr(mesh, &msg.rtm);
 907                         break;
 908
 909                 default:
 910                         break;
 911                 }
 912         }
 913 }
 914 #endif
 915
 916 bool discovery_start(meshlink_handle_t *mesh) {
 917         logger(mesh, MESHLINK_DEBUG, "discovery_start called\n");
 918
 919         assert(mesh);
 920
 921         // Set up multicast sockets for mDNS
 922         static const int one = 1;
 923         static const int ttl = 255;
 924         static const uint8_t one8 = 1;
 925         static const uint8_t ttl8 = 255;
 926
 927         int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 928
 929         if(fd == -1) {
 930                 logger(mesh, MESHLINK_ERROR, "Error creating IPv4 socket: %s", strerror(errno));
 931         } else {
 932
 933                 sockaddr_t sa4 = {
 934                         .in.sin_family = AF_INET,
 935                         .in.sin_port = ntohs(5353),
 936                 };
 937                 setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 938 #ifdef SO_REUSEPORT
 939                 setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 940 #endif
 941 #ifdef IP_PKTINFO
 942                 setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
 943 #endif
 944                 setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one8, sizeof(one8));
 945                 setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl8, sizeof(ttl8));
 946
 947                 if(bind(fd, &sa4.sa, SALEN(sa4.sa)) == -1) {
 948                         logger(mesh, MESHLINK_ERROR, "Error binding to IPv4 multicast socket: %s", strerror(errno));
 949                 } else {
 950                         io_add(&mesh->loop, &mesh->discovery.sockets[0], mdns_io_handler, &mesh->discovery.sockets[0], fd, IO_READ);
 951                 }
 952         }
 953
 954         fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
 955
 956         if(fd == -1) {
 957                 logger(mesh, MESHLINK_ERROR, "Error creating IPv6 socket: %s", strerror(errno));
 958         } else {
 959                 sockaddr_t sa6 = {
 960                         .in6.sin6_family = AF_INET6,
 961                         .in6.sin6_port = ntohs(5353),
 962                 };
 963
 964                 setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 965 #ifdef SO_REUSEPORT
 966                 setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 967 #endif
 968 #ifdef IPV6_RECVPKTINFO
 969                 setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
 970 #endif
 971                 setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
 972                 setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
 973                 setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
 974                 setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
 975
 976                 if(bind(fd, &sa6.sa, SALEN(sa6.sa)) == -1) {
 977                         logger(mesh, MESHLINK_ERROR, "Error binding to IPv6 multicast socket: %s", strerror(errno));
 978                 } else {
 979                         io_add(&mesh->loop, &mesh->discovery.sockets[1], mdns_io_handler, &mesh->discovery.sockets[1], fd, IO_READ);
 980                 }
 981         }
 982
 983 #if defined(__linux)
 984         int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
 985
 986         if(sock != -1) {
 987                 struct sockaddr_nl sa;
 988                 memset(&sa, 0, sizeof(sa));
 989                 sa.nl_family = AF_NETLINK;
 990                 sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;
 991
 992                 if(bind(sock, (struct sockaddr *)&sa, sizeof(sa)) != -1) {
 993                         io_add(&mesh->loop, &mesh->discovery.pfroute_io, netlink_io_handler, NULL, sock, IO_READ);
 994                         netlink_getlink(sock);
 995                 } else {
 996                         logger(mesh, MESHLINK_WARNING, "Could not bind AF_NETLINK socket: %s", strerror(errno));
 997                         scan_ifaddrs(mesh);
 998                 }
 999         } else {
1000                 logger(mesh, MESHLINK_WARNING, "Could not open AF_NETLINK socket: %s", strerror(errno));
1001                 scan_ifaddrs(mesh);
1002         }
1003
1004 #elif defined(__APPLE__)
1005         pthread_create(&mesh->discovery.thread, NULL, network_change_handler, mesh);
1006         // TODO: Do we need to wait for the thread to start succesfully?
1007         scan_ifaddrs(mesh);
1008 #elif defined(RTM_NEWADDR)
1009         int sock = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC);
1010
1011         if(sock != -1) {
1012                 io_add(&mesh->loop, &mesh->discovery.pfroute_io, pfroute_io_handler, NULL, sock, IO_READ);
1013         } else {
1014                 logger(mesh, MESHLINK_WARNING, "Could not open PF_ROUTE socket: %s", strerror(errno));
1015         }
1016
1017         scan_ifaddrs(mesh);
1018 #endif
1019
1020         return true;
1021 }
1022
1023 void discovery_stop(meshlink_handle_t *mesh) {
1024         logger(mesh, MESHLINK_DEBUG, "discovery_stop called\n");
1025
1026         assert(mesh);
1027
1028         free(mesh->discovery.ifaces);
1029         free(mesh->discovery.addresses);
1030         mesh->discovery.ifaces = NULL;
1031         mesh->discovery.addresses = NULL;
1032         mesh->discovery.iface_count = 0;
1033         mesh->discovery.address_count = 0;
1034
1035 #if defined(__APPLE__)
1036
1037         if(mesh->discovery.runloop) {
1038                 CFRunLoopStop(mesh->discovery.runloop);
1039                 pthread_join(mesh->discovery.thread, NULL);
1040         }
1041
1042 #endif
1043
1044         if(mesh->discovery.pfroute_io.cb) {
1045                 close(mesh->discovery.pfroute_io.fd);
1046                 io_del(&mesh->loop, &mesh->discovery.pfroute_io);
1047         }
1048
1049         for(int i = 0; i < 2; i++) {
1050                 if(mesh->discovery.sockets[i].cb) {
1051                         close(mesh->discovery.sockets[i].fd);
1052                         io_del(&mesh->loop, &mesh->discovery.sockets[i]);
1053                 }
1054         }
1055 }
1056
1057 void discovery_refresh(meshlink_handle_t *mesh) {
1058         for(int i = 0; i < mesh->discovery.address_count; i++) {
1059                 if(mesh->discovery.addresses[i].up) {
1060                         send_mdns_packet(mesh, &mesh->discovery.addresses[i], false);
1061                 }
1062         }
1063 }