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

   1 #define __APPLE_USE_RFC_3542
   2 #include "system.h"
   3
   4 #if defined(__APPLE__)
   5 #include <CoreFoundation/CoreFoundation.h>
   6 #include <CoreFoundation/CFArray.h>
   7 #include <CoreFoundation/CFString.h>
   8 #include <SystemConfiguration/SystemConfiguration.h>
   9 #include <net/if.h>
  10 #include <netinet/in.h>
  11 #elif defined(__unix) && !defined(__linux)
  12 #include <net/if.h>
  13 #include <net/route.h>
  14 #include <netinet/in.h>
  15 #elif defined(__linux)
  16 #include <asm/types.h>
  17 #include <net/if.h>
  18 #include <linux/if_link.h>
  19 #include <linux/netlink.h>
  20 #include <linux/rtnetlink.h>
  21 #endif
  22
  23 #include "mdns.h"
  24 #include "meshlink_internal.h"
  25 #include "event.h"
  26 #include "discovery.h"
  27 #include "sockaddr.h"
  28 #include "logger.h"
  29 #include "netutl.h"
  30 #include "node.h"
  31 #include "connection.h"
  32 #include "utils.h"
  33 #include "xalloc.h"
  34
  35 #define MESHLINK_MDNS_SERVICE_TYPE "_%s._tcp"
  36 #define MESHLINK_MDNS_NAME_KEY "name"
  37 #define MESHLINK_MDNS_FINGERPRINT_KEY "fingerprint"
  38
  39 #ifndef MSG_NOSIGNAL
  40 #define MSG_NOSIGNAL 0
  41 #endif
  42
  43 #ifndef IPV6_ADD_MEMBERSHIP
  44 #define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
  45 #endif
  46
  47 #ifndef IPV6_DROP_MEMBERSHIP
  48 #define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
  49 #endif
  50
  51 static const sockaddr_t mdns_address_ipv4 = {
  52         .in.sin_family = AF_INET,
  53         .in.sin_addr.s_addr = 0xfb0000e0,
  54         .in.sin_port = 0xe914,
  55 };
  56
  57 static const sockaddr_t mdns_address_ipv6 = {
  58         .in6.sin6_family = AF_INET6,
  59         .in6.sin6_addr.s6_addr[0x0] = 0xfd,
  60         .in6.sin6_addr.s6_addr[0x1] = 0x02,
  61         .in6.sin6_addr.s6_addr[0xf] = 0xfb,
  62         .in6.sin6_port = 0xe914,
  63 };
  64
  65 typedef struct discovery_address {
  66         int index;
  67         bool up;
  68         sockaddr_t address;
  69 } discovery_address_t;
  70
  71 static int iface_compare(const void *va, const void *vb) {
  72         const int *a = va;
  73         const int *b = vb;
  74         return *a - *b;
  75 }
  76
  77 static int address_compare(const void *va, const void *vb) {
  78         const discovery_address_t *a = va;
  79         const discovery_address_t *b = vb;
  80
  81         if(a->index != b->index) {
  82                 return a->index - b->index;
  83         }
  84
  85         return sockaddrcmp_noport(&a->address, &b->address);
  86 }
  87
  88 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) {
  89 #ifdef IP_PKTINFO
  90         struct iovec iov  = {
  91                 .iov_base = data,
  92                 .iov_len = len,
  93         };
  94
  95         struct in_pktinfo pkti = {
  96                 .ipi_ifindex = index,
  97                 .ipi_addr = src->in.sin_addr,
  98         };
  99
 100         union {
 101                 char buf[CMSG_SPACE(sizeof(pkti))];
 102                 struct cmsghdr align;
 103         } u;
 104
 105         struct msghdr msg = {
 106                 .msg_name = (struct sockaddr *) &dest->sa,
 107                 .msg_namelen = SALEN(dest->sa),
 108                 .msg_iov = &iov,
 109                 .msg_iovlen = 1,
 110                 .msg_control = u.buf,
 111                 .msg_controllen = sizeof(u.buf),
 112         };
 113
 114
 115         struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
 116         cmsg->cmsg_level = IPPROTO_IP;
 117         cmsg->cmsg_type = IP_PKTINFO;
 118         cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
 119         memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
 120
 121         // Send the packet
 122         ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
 123 #else
 124         (void)index;
 125         (void)src;
 126
 127         // Send the packet
 128         ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
 129 #endif
 130
 131         if(result <= 0) {
 132                 logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
 133         }
 134 }
 135
 136 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) {
 137 #ifdef IPV6_PKTINFO
 138         struct iovec iov  = {
 139                 .iov_base = data,
 140                 .iov_len = len,
 141         };
 142
 143         struct in6_pktinfo pkti = {
 144                 .ipi6_ifindex = index,
 145                 .ipi6_addr = src->in6.sin6_addr,
 146         };
 147
 148         union {
 149                 char buf[CMSG_SPACE(sizeof(pkti))];
 150                 struct cmsghdr align;
 151         } u;
 152
 153         memset(&u, 0, sizeof u);
 154
 155         struct msghdr msg = {
 156                 .msg_name = (struct sockaddr *) &dest->sa,
 157                 .msg_namelen = SALEN(dest->sa),
 158                 .msg_iov = &iov,
 159                 .msg_iovlen = 1,
 160                 .msg_control = u.buf,
 161                 .msg_controllen = CMSG_LEN(sizeof(pkti)),
 162         };
 163
 164         struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg);
 165         cmsg->cmsg_level = IPPROTO_IPV6;
 166         cmsg->cmsg_type = IPV6_PKTINFO;
 167         cmsg->cmsg_len = CMSG_LEN(sizeof(pkti));
 168         memcpy(CMSG_DATA(cmsg), &pkti, sizeof(pkti));
 169
 170         // Send the packet
 171         ssize_t result = sendmsg(fd, &msg, MSG_DONTWAIT | MSG_NOSIGNAL);
 172 #else
 173         (void)index;
 174         (void)src;
 175
 176         // Send the packet
 177         ssize_t result = sendto(fd, data, len, MSG_DONTWAIT | MSG_NOSIGNAL, &dest->sa, SALEN(dest->sa));
 178 #endif
 179
 180         if(result <= 0) {
 181                 logger(mesh, MESHLINK_ERROR, "Error sending multicast packet: %s", strerror(errno));
 182         }
 183 }
 184
 185 static void send_mdns_packet(meshlink_handle_t *mesh, const discovery_address_t *addr) {
 186         // Configure the socket to send the packet to the right interface
 187         int fd;
 188         uint8_t request[1024], response[1024];
 189         char *fingerprint = meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self);
 190         const char *keys[] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
 191         const char *values[] = {mesh->name, fingerprint};
 192         size_t request_size = prepare_request(request, sizeof request, mesh->appname, "tcp");
 193         size_t response_size = prepare_response(response, sizeof response, fingerprint, mesh->appname, "tcp", atoi(mesh->myport), 2, keys, values);
 194         free(fingerprint);
 195
 196         switch(addr->address.sa.sa_family) {
 197         case AF_INET:
 198                 fd = mesh->discovery.sockets[0].fd;
 199 #ifdef IP_MULTICAST_IF
 200                 {
 201                         struct ip_mreqn mreq = {
 202                                 .imr_address = addr->address.in.sin_addr,
 203                                 .imr_ifindex = addr->index,
 204                         };
 205
 206                         if(setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &mreq, sizeof(mreq)) != 0) {
 207                                 logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv4 socket");
 208                                 return;
 209                         }
 210                 }
 211
 212 #endif
 213
 214                 send_mdns_packet_ipv4(mesh, fd, addr->index, &addr->address, &mdns_address_ipv4, request, request_size);
 215                 send_mdns_packet_ipv4(mesh, fd, addr->index, &addr->address, &mdns_address_ipv4, response, response_size);
 216                 break;
 217
 218         case AF_INET6:
 219                 fd = mesh->discovery.sockets[1].fd;
 220 #ifdef IPV6_MULTICAST_IF
 221
 222                 if(setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &addr->index, sizeof(addr->index)) != 0) {
 223                         logger(mesh, MESHLINK_ERROR, "Could not set outgoing multicast interface on IPv6 socket");
 224                         return;
 225                 }
 226
 227 #endif
 228
 229                 send_mdns_packet_ipv6(mesh, fd, addr->index, &addr->address, &mdns_address_ipv6, request, request_size);
 230                 send_mdns_packet_ipv6(mesh, fd, addr->index, &addr->address, &mdns_address_ipv6, response, response_size);
 231                 break;
 232
 233         default:
 234                 break;
 235         }
 236 }
 237
 238 static void mdns_io_handler(event_loop_t *loop, void *data, int flags) {
 239         (void)flags;
 240         meshlink_handle_t *mesh = loop->data;
 241         io_t *io = data;
 242         uint8_t buf[1024];
 243         sockaddr_t sa;
 244         socklen_t sl = sizeof(sa);
 245
 246         ssize_t len = recvfrom(io->fd, buf, sizeof(buf), MSG_DONTWAIT, &sa.sa, &sl);
 247
 248         if(len == -1) {
 249                 if(!sockwouldblock(errno)) {
 250                         logger(mesh, MESHLINK_ERROR, "Error reading from mDNS discovery socket: %s", strerror(errno));
 251                         io_set(loop, io, 0);
 252                 }
 253
 254                 return;
 255         }
 256
 257         char *name = NULL;
 258         uint16_t port = 0;
 259         const char *keys[2] = {MESHLINK_MDNS_NAME_KEY, MESHLINK_MDNS_FINGERPRINT_KEY};
 260         char *values[2] = {NULL, NULL};
 261
 262         if(parse_response(buf, len, &name, mesh->appname, "tcp", &port, 2, keys, values)) {
 263                 node_t *n = (node_t *)meshlink_get_node(mesh, values[0]);
 264
 265                 if(n) {
 266                         if(n != mesh->self) {
 267                                 logger(mesh, MESHLINK_INFO, "Node %s discovered on the local network.\n", n->name);
 268                         }
 269
 270                         switch(sa.sa.sa_family) {
 271                         case AF_INET:
 272                                 sa.in.sin_port = htons(port);
 273                                 break;
 274
 275                         case AF_INET6:
 276                                 sa.in6.sin6_port = htons(port);
 277                                 break;
 278
 279                         default:
 280                                 logger(mesh, MESHLINK_WARNING, "Could not resolve node %s to a known address family type.\n", n->name);
 281                                 sa.sa.sa_family = AF_UNKNOWN;
 282                                 break;
 283                         }
 284
 285                         if(sa.sa.sa_family != AF_UNKNOWN) {
 286                                 n->catta_address = sa;
 287                                 n->last_connect_try = 0;
 288                                 node_add_recent_address(mesh, n, &sa);
 289
 290                                 if(n->connection) {
 291                                         n->connection->last_ping_time = -3600;
 292                                 }
 293
 294                                 for list_each(outgoing_t, outgoing, mesh->outgoings) {
 295                                         if(outgoing->node != n) {
 296                                                 continue;
 297                                         }
 298
 299                                         outgoing->timeout = 0;
 300
 301                                         if(outgoing->ev.cb) {
 302                                                 timeout_set(&mesh->loop, &outgoing->ev, &(struct timespec) {
 303                                                         0, 0
 304                                                 });
 305                                         }
 306                                 }
 307                         }
 308                 }
 309         } else if(parse_request(buf, len, mesh->appname, "tcp")) {
 310                 // Send a unicast response back
 311                 char *fingerprint = meshlink_get_fingerprint(mesh, (meshlink_node_t *)mesh->self);
 312                 const char *response_values[] = {mesh->name, fingerprint};
 313                 size_t size = prepare_response(buf, sizeof(buf), fingerprint, mesh->appname, "tcp", atoi(mesh->myport), 2, keys, response_values);
 314                 sendto(io->fd, buf, size, MSG_DONTWAIT | MSG_NOSIGNAL, &sa.sa, sl);
 315                 free(fingerprint);
 316         }
 317
 318         free(name);
 319
 320         for(int i = 0; i < 2; i++) {
 321                 free(values[i]);
 322         }
 323 }
 324
 325 static void iface_up(meshlink_handle_t *mesh, int index) {
 326         int *p = bsearch(&index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 327
 328         if(p) {
 329                 return;
 330         }
 331
 332         mesh->discovery.ifaces = xrealloc(mesh->discovery.ifaces, ++mesh->discovery.iface_count * sizeof(*p));
 333         mesh->discovery.ifaces[mesh->discovery.iface_count - 1] = index;
 334         qsort(mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 335
 336         // Add multicast membership
 337         struct ip_mreqn mreq4 = {
 338                 .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
 339                 .imr_ifindex = index,
 340         };
 341         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
 342         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq4, sizeof(mreq4));
 343
 344         struct ipv6_mreq mreq6 = {
 345                 .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
 346                 .ipv6mr_interface = index,
 347         };
 348         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
 349         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP, &mreq6, sizeof(mreq6));
 350
 351         // Send an announcement for all addresses associated with this interface
 352         for(int i = 0; i < mesh->discovery.address_count; i++) {
 353                 if(mesh->discovery.addresses[i].index == index) {
 354                         send_mdns_packet(mesh, &mesh->discovery.addresses[i]);
 355                 }
 356         }
 357
 358         handle_network_change(mesh, true);
 359 }
 360
 361 static void iface_down(meshlink_handle_t *mesh, int index) {
 362         int *p = bsearch(&index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(*p), iface_compare);
 363
 364         if(!p) {
 365                 return;
 366         }
 367
 368         // Drop multicast membership
 369         struct ip_mreqn mreq4 = {
 370                 .imr_multiaddr = mdns_address_ipv4.in.sin_addr,
 371                 .imr_ifindex = index,
 372         };
 373         setsockopt(mesh->discovery.sockets[0].fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq4, sizeof(mreq4));
 374
 375         struct ipv6_mreq mreq6 = {
 376                 .ipv6mr_multiaddr = mdns_address_ipv6.in6.sin6_addr,
 377                 .ipv6mr_interface = index,
 378         };
 379         setsockopt(mesh->discovery.sockets[1].fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6));
 380
 381         memmove(p, p + 1, (mesh->discovery.ifaces + --mesh->discovery.iface_count - p) * sizeof(*p));
 382
 383         handle_network_change(mesh, mesh->discovery.iface_count);
 384 }
 385
 386 static void addr_add(meshlink_handle_t *mesh, const discovery_address_t *addr) {
 387         discovery_address_t *p = bsearch(addr, mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 388
 389         if(p) {
 390                 return;
 391         }
 392
 393         bool up = bsearch(&addr->index, mesh->discovery.ifaces, mesh->discovery.iface_count, sizeof(int), iface_compare);
 394
 395         mesh->discovery.addresses = xrealloc(mesh->discovery.addresses, ++mesh->discovery.address_count * sizeof(*p));
 396         mesh->discovery.addresses[mesh->discovery.address_count - 1] = *addr;
 397         mesh->discovery.addresses[mesh->discovery.address_count - 1].up = up;
 398
 399         if(up) {
 400                 send_mdns_packet(mesh, &mesh->discovery.addresses[mesh->discovery.address_count - 1]);
 401         }
 402
 403         qsort(mesh->discovery.addresses, mesh->discovery.address_count, sizeof(*p), address_compare);
 404 }
 405
 406 static void addr_del(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         memmove(p, p + 1, (mesh->discovery.addresses + --mesh->discovery.address_count - p) * sizeof(*p));
 414 }
 415
 416 #if !defined(__linux) && (defined(RTM_NEWADDR) || defined(__APPLE__))
 417 static void scan_ifaddrs(meshlink_handle_t *mesh) {
 418         struct ifaddrs *ifa = NULL;
 419
 420         if(getifaddrs(&ifa) == -1) {
 421                 logger(mesh, MESHLINK_ERROR, "Could not get list of interface addresses: %s", strerror(errno));
 422                 return;
 423         }
 424
 425         // Check for interfaces being removed
 426         for(int i = 0; i < mesh->discovery.iface_count;) {
 427                 bool found = false;
 428
 429                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 430                         if(!ifap->ifa_name) {
 431                                 continue;
 432                         }
 433
 434                         int index = if_nametoindex(ifap->ifa_name);
 435
 436                         if(mesh->discovery.ifaces[i] == index) {
 437                                 found = true;
 438                                 break;
 439                         }
 440                 }
 441
 442                 if(!found) {
 443                         iface_down(mesh, mesh->discovery.ifaces[i]);
 444                 } else {
 445                         i++;
 446                 }
 447         }
 448
 449         // Check for addresses being removed
 450         for(int i = 0; i < mesh->discovery.address_count;) {
 451                 discovery_address_t *p = &mesh->discovery.addresses[i];
 452                 bool found = false;
 453
 454                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 455                         if(!ifap->ifa_name || !ifap->ifa_addr) {
 456                                 continue;
 457                         }
 458
 459                         int index = if_nametoindex(ifap->ifa_name);
 460
 461                         if(p->index == index && sockaddrcmp_noport(&p->address, (sockaddr_t *)ifap->ifa_addr) == 0) {
 462                                 found = true;
 463                                 break;
 464                         }
 465                 }
 466
 467                 if(!found) {
 468                         (void)addr_del;
 469                         memmove(p, p + 1, (mesh->discovery.addresses + --mesh->discovery.address_count - p) * sizeof(*p));
 470                 } else {
 471                         i++;
 472                 }
 473         }
 474
 475         // Check for interfaces state changes and addresses going up
 476         for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 477                 if(!ifap->ifa_name) {
 478                         continue;
 479                 }
 480
 481                 int index = if_nametoindex(ifap->ifa_name);
 482
 483                 if(ifap->ifa_flags & IFF_UP && ifap->ifa_flags & IFF_MULTICAST && !(ifap->ifa_flags & IFF_LOOPBACK)) {
 484                         iface_up(mesh, index);
 485                 } else {
 486                         iface_down(mesh, index);
 487                 }
 488
 489                 if(!ifap->ifa_addr) {
 490                         continue;
 491                 }
 492
 493                 discovery_address_t addr  = {
 494                         .index = index,
 495                 };
 496
 497                 sockaddr_t *sa = (sockaddr_t *)ifap->ifa_addr;
 498
 499                 if(sa->sa.sa_family == AF_INET) {
 500                         memcpy(&addr.address.in, &sa->in, sizeof(sa->in));
 501                         addr.address.in.sin_port = ntohs(5353);
 502                 } else if(sa->sa.sa_family == AF_INET6) {
 503                         memcpy(&addr.address.in6, &sa->in6, sizeof(sa->in6));
 504                         addr.address.in6.sin6_port = ntohs(5353);
 505                 } else {
 506                         addr.address.sa.sa_family = AF_UNKNOWN;
 507                 }
 508
 509                 if(addr.address.sa.sa_family != AF_UNKNOWN) {
 510                         addr_add(mesh, &addr);
 511                 }
 512         }
 513
 514         freeifaddrs(ifa);
 515 }
 516 #endif
 517
 518 #if defined(__linux)
 519 static void netlink_getlink(int fd) {
 520         static const struct {
 521                 struct nlmsghdr nlm;
 522                 struct ifinfomsg ifi;
 523         } msg = {
 524                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifi)),
 525                 .nlm.nlmsg_type = RTM_GETLINK,
 526                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 527                 .nlm.nlmsg_seq = 1,
 528                 .ifi.ifi_family = AF_UNSPEC,
 529         };
 530         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 531 }
 532
 533 static void netlink_getaddr(int fd) {
 534         static const struct {
 535                 struct nlmsghdr nlm;
 536                 struct ifaddrmsg ifa;
 537         } msg = {
 538                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifa)),
 539                 .nlm.nlmsg_type = RTM_GETADDR,
 540                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 541                 .nlm.nlmsg_seq = 2,
 542                 .ifa.ifa_family = AF_UNSPEC,
 543         };
 544         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 545 }
 546
 547 static void netlink_parse_link(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 548         const struct ifinfomsg *ifi = (const struct ifinfomsg *)(nlm + 1);
 549
 550         if(ifi->ifi_flags & IFF_UP && ifi->ifi_flags & IFF_MULTICAST) {
 551                 iface_up(mesh, ifi->ifi_index);
 552         } else {
 553                 iface_down(mesh, ifi->ifi_index);
 554         }
 555 }
 556
 557 static void netlink_parse_addr(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 558         const struct ifaddrmsg *ifa = (const struct ifaddrmsg *)(nlm + 1);
 559         const uint8_t *ptr = (const uint8_t *)(ifa + 1);
 560         size_t len = nlm->nlmsg_len - (ptr - (const uint8_t *)nlm);
 561
 562         while(len >= sizeof(struct rtattr)) {
 563                 const struct rtattr *rta = (const struct rtattr *)ptr;
 564
 565                 if(rta->rta_len <= 0 || rta->rta_len > len) {
 566                         break;
 567                 }
 568
 569                 if(rta->rta_type == IFA_ADDRESS) {
 570                         discovery_address_t addr  = {
 571                                 .index = ifa->ifa_index,
 572                         };
 573
 574                         if(rta->rta_len == 8) {
 575                                 addr.address.sa.sa_family = AF_INET;
 576                                 memcpy(&addr.address.in.sin_addr, ptr + 4, 4);
 577                                 addr.address.in.sin_port = ntohs(5353);
 578                         } else if(rta->rta_len == 20) {
 579                                 addr.address.sa.sa_family = AF_INET6;
 580                                 memcpy(&addr.address.in6.sin6_addr, ptr + 4, 16);
 581                                 addr.address.in6.sin6_port = ntohs(5353);
 582                                 addr.address.in6.sin6_scope_id = ifa->ifa_index;
 583                         } else {
 584                                 addr.address.sa.sa_family = AF_UNKNOWN;
 585                         }
 586
 587                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 588                                 if(nlm->nlmsg_type == RTM_NEWADDR) {
 589                                         addr_add(mesh, &addr);
 590                                 } else {
 591                                         addr_del(mesh, &addr);
 592                                 }
 593                         }
 594                 }
 595
 596                 unsigned short rta_len = (rta->rta_len + 3) & ~3;
 597                 ptr += rta_len;
 598                 len -= rta_len;
 599         }
 600 }
 601
 602 static void netlink_parse(meshlink_handle_t *mesh, const void *data, size_t len) {
 603         const uint8_t *ptr = data;
 604
 605         while(len >= sizeof(struct nlmsghdr)) {
 606                 const struct nlmsghdr *nlm = (const struct nlmsghdr *)ptr;
 607
 608                 if(nlm->nlmsg_len > len) {
 609                         break;
 610                 }
 611
 612                 switch(nlm->nlmsg_type) {
 613                 case RTM_NEWLINK:
 614                 case RTM_DELLINK:
 615                         netlink_parse_link(mesh, nlm);
 616                         break;
 617
 618                 case RTM_NEWADDR:
 619                 case RTM_DELADDR:
 620                         netlink_parse_addr(mesh, nlm);
 621                 }
 622
 623                 ptr += nlm->nlmsg_len;
 624                 len -= nlm->nlmsg_len;
 625         }
 626 }
 627
 628 static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
 629         (void)flags;
 630         (void)data;
 631         meshlink_handle_t *mesh = loop->data;
 632
 633         struct {
 634                 struct nlmsghdr nlm;
 635                 char data[16384];
 636         } msg;
 637
 638         while(true) {
 639                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 640
 641                 if(result <= 0) {
 642                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 643                                 break;
 644                         }
 645
 646                         logger(mesh, MESHLINK_ERROR, "Reading from Netlink socket failed: %s\n", strerror(errno));
 647                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 648                 }
 649
 650                 if((size_t)result < sizeof(msg.nlm)) {
 651                         logger(mesh, MESHLINK_ERROR, "Invalid Netlink message\n");
 652                         break;
 653                 }
 654
 655                 if(msg.nlm.nlmsg_type == NLMSG_DONE) {
 656                         if(msg.nlm.nlmsg_seq == 1) {
 657                                 // We just got the result of GETLINK, now send GETADDR.
 658                                 netlink_getaddr(mesh->discovery.pfroute_io.fd);
 659                         }
 660                 } else {
 661                         netlink_parse(mesh, &msg, result);
 662
 663                         if(loop->now.tv_sec > mesh->discovery.last_update + 5) {
 664                                 mesh->discovery.last_update = loop->now.tv_sec;
 665                                 handle_network_change(mesh, 1);
 666                         }
 667                 }
 668         }
 669 }
 670 #elif defined(__APPLE__)
 671 static void network_change_callback(SCDynamicStoreRef store, CFArrayRef keys, void *info) {
 672         (void)store;
 673         (void)keys;
 674
 675         meshlink_handle_t *mesh = info;
 676
 677         pthread_mutex_lock(&mesh->mutex);
 678
 679         logger(mesh, MESHLINK_ERROR, "Network change detected!");
 680         scan_ifaddrs(mesh);
 681
 682         if(mesh->loop.now.tv_sec > mesh->discovery.last_update + 5) {
 683                 mesh->discovery.last_update = mesh->loop.now.tv_sec;
 684                 handle_network_change(mesh, 1);
 685         }
 686
 687         pthread_mutex_unlock(&mesh->mutex);
 688 }
 689
 690 static void *network_change_handler(void *arg) {
 691         meshlink_handle_t *mesh = arg;
 692
 693         mesh->discovery.runloop = CFRunLoopGetCurrent();
 694
 695         SCDynamicStoreContext context = {0, mesh, NULL, NULL, NULL};
 696         SCDynamicStoreRef store = SCDynamicStoreCreate(NULL, CFSTR("network_change_handler"), network_change_callback, &context);
 697         CFStringRef interfaces = SCDynamicStoreKeyCreate(NULL, CFSTR("State:/Network/Interface"), kCFStringEncodingUTF8);
 698         CFStringRef ipv4 = SCDynamicStoreKeyCreateNetworkInterfaceEntity(NULL, kSCDynamicStoreDomainState, kSCCompAnyRegex, kSCEntNetIPv4);
 699         CFStringRef ipv6 = SCDynamicStoreKeyCreateNetworkInterfaceEntity(NULL, kSCDynamicStoreDomainState, kSCCompAnyRegex, kSCEntNetIPv6);
 700         CFMutableArrayRef keys = CFArrayCreateMutable(NULL, 0, &kCFTypeArrayCallBacks);
 701         CFMutableArrayRef patterns = CFArrayCreateMutable(NULL, 0, &kCFTypeArrayCallBacks);
 702         CFRunLoopSourceRef runloop_source = NULL;
 703
 704         if(!store) {
 705                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 706                 goto exit;
 707         }
 708
 709         if(!interfaces || !ipv4 || !ipv6 || !keys || !patterns) {
 710                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 711                 goto exit;
 712         }
 713
 714         CFArrayAppendValue(keys, interfaces);
 715         CFArrayAppendValue(patterns, ipv4);
 716         CFArrayAppendValue(patterns, ipv6);
 717
 718         if(!SCDynamicStoreSetNotificationKeys(store, keys, patterns)) {
 719                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 720                 goto exit;
 721         }
 722
 723         runloop_source = SCDynamicStoreCreateRunLoopSource(NULL, store, 0);
 724
 725         if(!runloop_source) {
 726                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 727                 goto exit;
 728         }
 729
 730         CFRunLoopAddSource(CFRunLoopGetCurrent(), runloop_source, kCFRunLoopDefaultMode);
 731         CFRunLoopRun();
 732
 733 exit:
 734
 735         if(runloop_source) {
 736                 CFRelease(runloop_source);
 737         }
 738
 739         if(interfaces) {
 740                 CFRelease(interfaces);
 741         }
 742
 743         if(ipv4) {
 744                 CFRelease(ipv4);
 745         }
 746
 747         if(ipv6) {
 748                 CFRelease(ipv6);
 749         }
 750
 751         if(keys) {
 752                 CFRelease(keys);
 753         }
 754
 755         if(patterns) {
 756                 CFRelease(patterns);
 757         }
 758
 759         if(store) {
 760                 CFRelease(store);
 761         }
 762
 763         mesh->discovery.runloop = NULL;
 764
 765         return NULL;
 766
 767 }
 768 #elif defined(RTM_NEWADDR)
 769 static void pfroute_parse_iface(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 770         const struct if_msghdr *ifm = (const struct if_msghdr *)rtm;
 771
 772         if(ifm->ifm_flags & IFF_UP && ifm->ifm_flags & IFF_MULTICAST && !(ifm->ifm_flags & IFF_LOOPBACK)) {
 773                 iface_up(mesh, ifm->ifm_index);
 774         } else {
 775                 iface_down(mesh, ifm->ifm_index);
 776         }
 777 }
 778
 779 static void pfroute_parse_addr(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 780         const struct ifa_msghdr *ifam = (const struct ifa_msghdr *)rtm;
 781         const char *p = (const char *)(ifam + 1);
 782
 783         for(unsigned int i = 1; i; i <<= 1) {
 784                 if(!(ifam->ifam_addrs & i)) {
 785                         continue;
 786                 }
 787
 788                 const sockaddr_t *sa = (const sockaddr_t *)p;
 789
 790                 if(i == RTA_IFA) {
 791                         discovery_address_t addr = {
 792                                 .index = ifam->ifam_index,
 793                         };
 794
 795                         if(sa->sa.sa_family == AF_INET) {
 796                                 addr.address.in = sa->in;
 797                                 addr.address.in.sin_port = ntohs(5353);
 798                         } else if(sa->sa.sa_family == AF_INET6) {
 799                                 addr.address.in6 = sa->in6;
 800                                 addr.address.in6.sin6_port = ntohs(5353);
 801                         } else {
 802                                 addr.address.sa.sa_family = AF_UNKNOWN;
 803                         }
 804
 805                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 806                                 if(ifam->ifam_type == RTM_NEWADDR) {
 807                                         addr_add(mesh, &addr);
 808                                 } else {
 809                                         addr_del(mesh, &addr);
 810                                 }
 811                         }
 812
 813                         break;
 814                 }
 815
 816                 size_t len = (sa->sa.sa_len + 3) & ~3;
 817                 p += len;
 818         }
 819 }
 820
 821 static void pfroute_io_handler(event_loop_t *loop, void *data, int flags) {
 822         (void)flags;
 823         (void)data;
 824         meshlink_handle_t *mesh = loop->data;
 825
 826         struct {
 827                 struct rt_msghdr rtm;
 828                 char data[2048];
 829         } msg;
 830
 831         while(true) {
 832                 msg.rtm.rtm_version = 0;
 833                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 834
 835                 if(result <= 0) {
 836                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 837                                 break;
 838                         }
 839
 840                         logger(mesh, MESHLINK_ERROR, "Reading from PFROUTE socket failed: %s\n", strerror(errno));
 841                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 842                 }
 843
 844                 if(msg.rtm.rtm_version != RTM_VERSION) {
 845                         logger(mesh, MESHLINK_ERROR, "Invalid PFROUTE message version\n");
 846                         break;
 847                 }
 848
 849                 switch(msg.rtm.rtm_type) {
 850                 case RTM_IFINFO:
 851                         pfroute_parse_iface(mesh, &msg.rtm);
 852                         break;
 853
 854                 case RTM_NEWADDR:
 855                 case RTM_DELADDR:
 856                         pfroute_parse_addr(mesh, &msg.rtm);
 857                         break;
 858
 859                 default:
 860                         break;
 861                 }
 862         }
 863 }
 864 #endif
 865
 866 bool discovery_start(meshlink_handle_t *mesh) {
 867         logger(mesh, MESHLINK_DEBUG, "discovery_start called\n");
 868
 869         assert(mesh);
 870
 871         // Set up multicast sockets for mDNS
 872         static const int one = 1;
 873         static const int ttl = 255;
 874         static const uint8_t one8 = 1;
 875         static const uint8_t ttl8 = 255;
 876
 877         int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 878
 879         if(fd == -1) {
 880                 logger(mesh, MESHLINK_ERROR, "Error creating IPv4 socket: %s", strerror(errno));
 881         }
 882
 883         sockaddr_t sa4 = {
 884                 .in.sin_family = AF_INET,
 885                 .in.sin_port = ntohs(5353),
 886         };
 887         setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 888         setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 889         setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one8, sizeof(one8));
 890         setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl8, sizeof(ttl8));
 891
 892         if(bind(fd, &sa4.sa, SALEN(sa4.sa)) == -1) {
 893                 logger(mesh, MESHLINK_ERROR, "Error binding to IPv4 multicast socket: %s", strerror(errno));
 894         } else {
 895                 io_add(&mesh->loop, &mesh->discovery.sockets[0], mdns_io_handler, &mesh->discovery.sockets[0], fd, IO_READ);
 896         }
 897
 898         sockaddr_t sa6 = {
 899                 .in6.sin6_family = AF_INET6,
 900                 .in6.sin6_port = ntohs(5353),
 901         };
 902         fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
 903
 904         if(fd == -1) {
 905                 logger(mesh, MESHLINK_ERROR, "Error creating IPv6 socket: %s", strerror(errno));
 906         }
 907
 908         setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 909         setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 910         setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
 911         setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
 912         setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
 913         setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
 914
 915         if(bind(fd, &sa6.sa, SALEN(sa6.sa)) == -1) {
 916                 logger(mesh, MESHLINK_ERROR, "Error binding to IPv4 multicast socket: %s", strerror(errno));
 917         } else {
 918                 io_add(&mesh->loop, &mesh->discovery.sockets[1], mdns_io_handler, &mesh->discovery.sockets[1], fd, IO_READ);
 919         }
 920
 921 #if defined(__linux)
 922         int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
 923
 924         if(sock != -1) {
 925                 struct sockaddr_nl sa;
 926                 memset(&sa, 0, sizeof(sa));
 927                 sa.nl_family = AF_NETLINK;
 928                 sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;
 929
 930                 if(bind(sock, (struct sockaddr *)&sa, sizeof(sa)) != -1) {
 931                         io_add(&mesh->loop, &mesh->discovery.pfroute_io, netlink_io_handler, NULL, sock, IO_READ);
 932                         netlink_getlink(sock);
 933                 } else {
 934                         logger(mesh, MESHLINK_WARNING, "Could not bind AF_NETLINK socket: %s", strerror(errno));
 935                 }
 936         } else {
 937                 logger(mesh, MESHLINK_WARNING, "Could not open AF_NETLINK socket: %s", strerror(errno));
 938         }
 939
 940 #elif defined(__APPLE__)
 941         pthread_create(&mesh->discovery.thread, NULL, network_change_handler, mesh);
 942         // TODO: Do we need to wait for the thread to start succesfully?
 943         scan_ifaddrs(mesh);
 944 #elif defined(RTM_NEWADDR)
 945         int sock = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC);
 946
 947         if(sock != -1) {
 948                 io_add(&mesh->loop, &mesh->discovery.pfroute_io, pfroute_io_handler, NULL, sock, IO_READ);
 949         } else {
 950                 logger(mesh, MESHLINK_WARNING, "Could not open PF_ROUTE socket: %s", strerror(errno));
 951         }
 952
 953         scan_ifaddrs(mesh);
 954 #endif
 955
 956         return true;
 957 }
 958
 959 void discovery_stop(meshlink_handle_t *mesh) {
 960         logger(mesh, MESHLINK_DEBUG, "discovery_stop called\n");
 961
 962         assert(mesh);
 963
 964         free(mesh->discovery.ifaces);
 965         free(mesh->discovery.addresses);
 966         mesh->discovery.ifaces = NULL;
 967         mesh->discovery.addresses = NULL;
 968         mesh->discovery.iface_count = 0;
 969         mesh->discovery.address_count = 0;
 970
 971 #if defined(__APPLE__)
 972
 973         if(mesh->discovery.runloop) {
 974                 CFRunLoopStop(mesh->discovery.runloop);
 975                 pthread_join(mesh->discovery.thread, NULL);
 976         }
 977
 978 #endif
 979
 980         if(mesh->discovery.pfroute_io.cb) {
 981                 close(mesh->discovery.pfroute_io.fd);
 982                 io_del(&mesh->loop, &mesh->discovery.pfroute_io);
 983         }
 984
 985         for(int i = 0; i < 2; i++) {
 986                 if(mesh->discovery.sockets[i].cb) {
 987                         close(mesh->discovery.sockets[i].fd);
 988                         io_del(&mesh->loop, &mesh->discovery.sockets[i]);
 989                 }
 990         }
 991 }
 992
 993 void discovery_refresh(meshlink_handle_t *mesh) {
 994         for(int i = 0; i < mesh->discovery.address_count; i++) {
 995                 if(mesh->discovery.addresses[i].up) {
 996                         send_mdns_packet(mesh, &mesh->discovery.addresses[i]);
 997                 }
 998         }
 999 }