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