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         logger(mesh, MESHLINK_WARNING, "Calling getifaddrs()");
 438         struct ifaddrs *ifa = NULL;
 439
 440         if(getifaddrs(&ifa) == -1) {
 441                 logger(mesh, MESHLINK_ERROR, "Could not get list of interface addresses: %s", strerror(errno));
 442                 return;
 443         }
 444
 445         // Check for interfaces being removed
 446         for(int i = 0; i < mesh->discovery.iface_count;) {
 447                 bool found = false;
 448
 449                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 450                         if(!ifap->ifa_name) {
 451                                 continue;
 452                         }
 453
 454                         int index = if_nametoindex(ifap->ifa_name);
 455
 456                         if(mesh->discovery.ifaces[i] == index) {
 457                                 found = true;
 458                                 break;
 459                         }
 460                 }
 461
 462                 if(!found) {
 463                         iface_down(mesh, mesh->discovery.ifaces[i]);
 464                 } else {
 465                         i++;
 466                 }
 467         }
 468
 469         // Check for addresses being removed
 470         for(int i = 0; i < mesh->discovery.address_count;) {
 471                 discovery_address_t *p = &mesh->discovery.addresses[i];
 472                 bool found = false;
 473
 474                 for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 475                         if(!ifap->ifa_name || !ifap->ifa_addr) {
 476                                 continue;
 477                         }
 478
 479                         int index = if_nametoindex(ifap->ifa_name);
 480
 481                         if(p->index == index && sockaddrcmp_noport(&p->address, (sockaddr_t *)ifap->ifa_addr) == 0) {
 482                                 found = true;
 483                                 break;
 484                         }
 485                 }
 486
 487                 if(!found) {
 488                         (void)addr_del;
 489                         memmove(p, p + 1, (mesh->discovery.addresses + --mesh->discovery.address_count - p) * sizeof(*p));
 490                 } else {
 491                         i++;
 492                 }
 493         }
 494
 495         // Check for interfaces state changes and addresses going up
 496         for(struct ifaddrs *ifap = ifa; ifap; ifap = ifap->ifa_next) {
 497                 if(!ifap->ifa_name) {
 498                         continue;
 499                 }
 500
 501                 int index = if_nametoindex(ifap->ifa_name);
 502
 503                 if(ifap->ifa_flags & IFF_UP && ifap->ifa_flags & IFF_MULTICAST && !(ifap->ifa_flags & IFF_LOOPBACK)) {
 504                         iface_up(mesh, index);
 505                 } else {
 506                         iface_down(mesh, index);
 507                 }
 508
 509                 if(!ifap->ifa_addr) {
 510                         continue;
 511                 }
 512
 513                 discovery_address_t addr  = {
 514                         .index = index,
 515                 };
 516
 517                 sockaddr_t *sa = (sockaddr_t *)ifap->ifa_addr;
 518
 519                 if(sa->sa.sa_family == AF_INET) {
 520                         memcpy(&addr.address.in, &sa->in, sizeof(sa->in));
 521                         addr.address.in.sin_port = ntohs(5353);
 522                 } else if(sa->sa.sa_family == AF_INET6) {
 523                         memcpy(&addr.address.in6, &sa->in6, sizeof(sa->in6));
 524                         addr.address.in6.sin6_port = ntohs(5353);
 525                 } else {
 526                         addr.address.sa.sa_family = AF_UNKNOWN;
 527                 }
 528
 529                 if(addr.address.sa.sa_family != AF_UNKNOWN) {
 530                         char *host = NULL;
 531                         sockaddr2str(sa, &host, NULL);
 532                         logger(mesh, MESHLINK_WARNING, "iface %d (%s) address %s", index, ifap->ifa_name, host);
 533                         free(host);
 534                 }
 535
 536                 if(addr.address.sa.sa_family != AF_UNKNOWN) {
 537                         addr_add(mesh, &addr);
 538                 }
 539         }
 540
 541         freeifaddrs(ifa);
 542 #else
 543         logger(mesh, MESHLINK_ERROR, "getifaddrs() not supported");
 544 #endif
 545 }
 546
 547 #if defined(__linux)
 548 static void netlink_getlink(int fd) {
 549         static const struct {
 550                 struct nlmsghdr nlm;
 551                 struct ifinfomsg ifi;
 552         } msg = {
 553                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifi)),
 554                 .nlm.nlmsg_type = RTM_GETLINK,
 555                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 556                 .nlm.nlmsg_seq = 1,
 557                 .ifi.ifi_family = AF_UNSPEC,
 558         };
 559         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 560 }
 561
 562 static void netlink_getaddr(int fd) {
 563         static const struct {
 564                 struct nlmsghdr nlm;
 565                 struct ifaddrmsg ifa;
 566         } msg = {
 567                 .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifa)),
 568                 .nlm.nlmsg_type = RTM_GETADDR,
 569                 .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
 570                 .nlm.nlmsg_seq = 2,
 571                 .ifa.ifa_family = AF_UNSPEC,
 572         };
 573         send(fd, &msg, msg.nlm.nlmsg_len, 0);
 574 }
 575
 576 static void netlink_parse_link(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 577         const struct ifinfomsg *ifi = (const struct ifinfomsg *)(nlm + 1);
 578
 579         if(ifi->ifi_flags & IFF_UP && ifi->ifi_flags & IFF_MULTICAST) {
 580                 iface_up(mesh, ifi->ifi_index);
 581         } else {
 582                 iface_down(mesh, ifi->ifi_index);
 583         }
 584 }
 585
 586 static void netlink_parse_addr(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
 587         const struct ifaddrmsg *ifa = (const struct ifaddrmsg *)(nlm + 1);
 588         const uint8_t *ptr = (const uint8_t *)(ifa + 1);
 589         size_t len = nlm->nlmsg_len - (ptr - (const uint8_t *)nlm);
 590
 591         while(len >= sizeof(struct rtattr)) {
 592                 const struct rtattr *rta = (const struct rtattr *)ptr;
 593
 594                 if(rta->rta_len <= 0 || rta->rta_len > len) {
 595                         break;
 596                 }
 597
 598                 if(rta->rta_type == IFA_ADDRESS) {
 599                         discovery_address_t addr  = {
 600                                 .index = ifa->ifa_index,
 601                         };
 602
 603                         if(rta->rta_len == 8) {
 604                                 addr.address.sa.sa_family = AF_INET;
 605                                 memcpy(&addr.address.in.sin_addr, ptr + 4, 4);
 606                                 addr.address.in.sin_port = ntohs(5353);
 607                         } else if(rta->rta_len == 20) {
 608                                 addr.address.sa.sa_family = AF_INET6;
 609                                 memcpy(&addr.address.in6.sin6_addr, ptr + 4, 16);
 610                                 addr.address.in6.sin6_port = ntohs(5353);
 611                                 addr.address.in6.sin6_scope_id = ifa->ifa_index;
 612                         } else {
 613                                 addr.address.sa.sa_family = AF_UNKNOWN;
 614                         }
 615
 616                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 617                                 if(nlm->nlmsg_type == RTM_NEWADDR) {
 618                                         addr_add(mesh, &addr);
 619                                 } else {
 620                                         addr_del(mesh, &addr);
 621                                 }
 622                         }
 623                 }
 624
 625                 unsigned short rta_len = (rta->rta_len + 3) & ~3;
 626                 ptr += rta_len;
 627                 len -= rta_len;
 628         }
 629 }
 630
 631 static void netlink_parse(meshlink_handle_t *mesh, const void *data, size_t len) {
 632         const uint8_t *ptr = data;
 633
 634         while(len >= sizeof(struct nlmsghdr)) {
 635                 const struct nlmsghdr *nlm = (const struct nlmsghdr *)ptr;
 636
 637                 if(nlm->nlmsg_len > len) {
 638                         break;
 639                 }
 640
 641                 switch(nlm->nlmsg_type) {
 642                 case RTM_NEWLINK:
 643                 case RTM_DELLINK:
 644                         netlink_parse_link(mesh, nlm);
 645                         break;
 646
 647                 case RTM_NEWADDR:
 648                 case RTM_DELADDR:
 649                         netlink_parse_addr(mesh, nlm);
 650                 }
 651
 652                 ptr += nlm->nlmsg_len;
 653                 len -= nlm->nlmsg_len;
 654         }
 655 }
 656
 657 static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
 658         (void)flags;
 659         (void)data;
 660         meshlink_handle_t *mesh = loop->data;
 661
 662         struct {
 663                 struct nlmsghdr nlm;
 664                 char data[16384];
 665         } msg;
 666
 667         while(true) {
 668                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 669
 670                 if(result <= 0) {
 671                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 672                                 break;
 673                         }
 674
 675                         logger(mesh, MESHLINK_ERROR, "Reading from Netlink socket failed: %s\n", strerror(errno));
 676                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 677                 }
 678
 679                 if((size_t)result < sizeof(msg.nlm)) {
 680                         logger(mesh, MESHLINK_ERROR, "Invalid Netlink message\n");
 681                         break;
 682                 }
 683
 684                 if(msg.nlm.nlmsg_type == NLMSG_DONE) {
 685                         if(msg.nlm.nlmsg_seq == 1) {
 686                                 // We just got the result of GETLINK, now send GETADDR.
 687                                 netlink_getaddr(mesh->discovery.pfroute_io.fd);
 688                         }
 689                 } else {
 690                         netlink_parse(mesh, &msg, result);
 691
 692                         if(loop->now.tv_sec > mesh->discovery.last_update + 5) {
 693                                 mesh->discovery.last_update = loop->now.tv_sec;
 694                                 handle_network_change(mesh, 1);
 695                         }
 696                 }
 697         }
 698 }
 699 #elif defined(__APPLE__)
 700 static void network_change_callback(SCDynamicStoreRef store, CFArrayRef keys, void *info) {
 701         (void)store;
 702         (void)keys;
 703
 704         meshlink_handle_t *mesh = info;
 705
 706         pthread_mutex_lock(&mesh->mutex);
 707
 708         logger(mesh, MESHLINK_ERROR, "Network change detected!");
 709         scan_ifaddrs(mesh);
 710
 711         if(mesh->loop.now.tv_sec > mesh->discovery.last_update + 5) {
 712                 mesh->discovery.last_update = mesh->loop.now.tv_sec;
 713                 handle_network_change(mesh, 1);
 714         }
 715
 716         pthread_mutex_unlock(&mesh->mutex);
 717 }
 718
 719 static void *network_change_handler(void *arg) {
 720         meshlink_handle_t *mesh = arg;
 721
 722         mesh->discovery.runloop = CFRunLoopGetCurrent();
 723
 724         SCDynamicStoreContext context = {0, mesh, NULL, NULL, NULL};
 725         SCDynamicStoreRef store = SCDynamicStoreCreate(NULL, CFSTR("network_change_handler"), network_change_callback, &context);
 726         CFStringRef interfaces = SCDynamicStoreKeyCreate(NULL, CFSTR("State:/Network/Interface"), kCFStringEncodingUTF8);
 727         CFStringRef ipv4 = SCDynamicStoreKeyCreateNetworkInterfaceEntity(NULL, kSCDynamicStoreDomainState, kSCCompAnyRegex, kSCEntNetIPv4);
 728         CFStringRef ipv6 = SCDynamicStoreKeyCreateNetworkInterfaceEntity(NULL, kSCDynamicStoreDomainState, kSCCompAnyRegex, kSCEntNetIPv6);
 729         CFMutableArrayRef keys = CFArrayCreateMutable(NULL, 0, &kCFTypeArrayCallBacks);
 730         CFMutableArrayRef patterns = CFArrayCreateMutable(NULL, 0, &kCFTypeArrayCallBacks);
 731         CFRunLoopSourceRef runloop_source = NULL;
 732
 733         if(!store) {
 734                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 735                 goto exit;
 736         }
 737
 738         if(!interfaces || !ipv4 || !ipv6 || !keys || !patterns) {
 739                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 740                 goto exit;
 741         }
 742
 743         CFArrayAppendValue(keys, interfaces);
 744         CFArrayAppendValue(patterns, ipv4);
 745         CFArrayAppendValue(patterns, ipv6);
 746
 747         if(!SCDynamicStoreSetNotificationKeys(store, keys, patterns)) {
 748                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 749                 goto exit;
 750         }
 751
 752         runloop_source = SCDynamicStoreCreateRunLoopSource(NULL, store, 0);
 753
 754         if(!runloop_source) {
 755                 logger(mesh, MESHLINK_ERROR, "Error setting up network change handler: %s\n", SCErrorString(SCError()));
 756                 goto exit;
 757         }
 758
 759         CFRunLoopAddSource(CFRunLoopGetCurrent(), runloop_source, kCFRunLoopDefaultMode);
 760         CFRunLoopRun();
 761
 762 exit:
 763
 764         if(runloop_source) {
 765                 CFRelease(runloop_source);
 766         }
 767
 768         if(interfaces) {
 769                 CFRelease(interfaces);
 770         }
 771
 772         if(ipv4) {
 773                 CFRelease(ipv4);
 774         }
 775
 776         if(ipv6) {
 777                 CFRelease(ipv6);
 778         }
 779
 780         if(keys) {
 781                 CFRelease(keys);
 782         }
 783
 784         if(patterns) {
 785                 CFRelease(patterns);
 786         }
 787
 788         if(store) {
 789                 CFRelease(store);
 790         }
 791
 792         mesh->discovery.runloop = NULL;
 793
 794         return NULL;
 795
 796 }
 797 #elif defined(RTM_NEWADDR)
 798 static void pfroute_parse_iface(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 799         const struct if_msghdr *ifm = (const struct if_msghdr *)rtm;
 800
 801         if(ifm->ifm_flags & IFF_UP && ifm->ifm_flags & IFF_MULTICAST && !(ifm->ifm_flags & IFF_LOOPBACK)) {
 802                 iface_up(mesh, ifm->ifm_index);
 803         } else {
 804                 iface_down(mesh, ifm->ifm_index);
 805         }
 806 }
 807
 808 static void pfroute_parse_addr(meshlink_handle_t *mesh, const struct rt_msghdr *rtm) {
 809         const struct ifa_msghdr *ifam = (const struct ifa_msghdr *)rtm;
 810         const char *p = (const char *)(ifam + 1);
 811
 812         for(unsigned int i = 1; i; i <<= 1) {
 813                 if(!(ifam->ifam_addrs & i)) {
 814                         continue;
 815                 }
 816
 817                 const sockaddr_t *sa = (const sockaddr_t *)p;
 818
 819                 if(i == RTA_IFA) {
 820                         discovery_address_t addr = {
 821                                 .index = ifam->ifam_index,
 822                         };
 823
 824                         if(sa->sa.sa_family == AF_INET) {
 825                                 addr.address.in = sa->in;
 826                                 addr.address.in.sin_port = ntohs(5353);
 827                         } else if(sa->sa.sa_family == AF_INET6) {
 828                                 addr.address.in6 = sa->in6;
 829                                 addr.address.in6.sin6_port = ntohs(5353);
 830                         } else {
 831                                 addr.address.sa.sa_family = AF_UNKNOWN;
 832                         }
 833
 834                         if(addr.address.sa.sa_family != AF_UNKNOWN) {
 835                                 if(ifam->ifam_type == RTM_NEWADDR) {
 836                                         addr_add(mesh, &addr);
 837                                 } else {
 838                                         addr_del(mesh, &addr);
 839                                 }
 840                         }
 841
 842                         break;
 843                 }
 844
 845                 size_t len = (sa->sa.sa_len + 3) & ~3;
 846                 p += len;
 847         }
 848 }
 849
 850 static void pfroute_io_handler(event_loop_t *loop, void *data, int flags) {
 851         (void)flags;
 852         (void)data;
 853         meshlink_handle_t *mesh = loop->data;
 854
 855         struct {
 856                 struct rt_msghdr rtm;
 857                 char data[2048];
 858         } msg;
 859
 860         while(true) {
 861                 msg.rtm.rtm_version = 0;
 862                 ssize_t result = recv(mesh->discovery.pfroute_io.fd, &msg, sizeof(msg), MSG_DONTWAIT);
 863
 864                 if(result <= 0) {
 865                         if(result == 0 || errno == EAGAIN || errno == EINTR) {
 866                                 break;
 867                         }
 868
 869                         logger(mesh, MESHLINK_ERROR, "Reading from PFROUTE socket failed: %s\n", strerror(errno));
 870                         io_set(loop, &mesh->discovery.pfroute_io, 0);
 871                 }
 872
 873                 if(msg.rtm.rtm_version != RTM_VERSION) {
 874                         logger(mesh, MESHLINK_ERROR, "Invalid PFROUTE message version\n");
 875                         break;
 876                 }
 877
 878                 switch(msg.rtm.rtm_type) {
 879                 case RTM_IFINFO:
 880                         pfroute_parse_iface(mesh, &msg.rtm);
 881                         break;
 882
 883                 case RTM_NEWADDR:
 884                 case RTM_DELADDR:
 885                         pfroute_parse_addr(mesh, &msg.rtm);
 886                         break;
 887
 888                 default:
 889                         break;
 890                 }
 891         }
 892 }
 893 #endif
 894
 895 bool discovery_start(meshlink_handle_t *mesh) {
 896         logger(mesh, MESHLINK_DEBUG, "discovery_start called\n");
 897
 898         assert(mesh);
 899
 900         // Set up multicast sockets for mDNS
 901         static const int one = 1;
 902         static const int ttl = 255;
 903         static const uint8_t one8 = 1;
 904         static const uint8_t ttl8 = 255;
 905
 906         int fd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 907
 908         if(fd == -1) {
 909                 logger(mesh, MESHLINK_ERROR, "Error creating IPv4 socket: %s", strerror(errno));
 910         }
 911
 912         sockaddr_t sa4 = {
 913                 .in.sin_family = AF_INET,
 914                 .in.sin_port = ntohs(5353),
 915         };
 916         setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 917         setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 918         setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one8, sizeof(one8));
 919         setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl8, sizeof(ttl8));
 920
 921         if(bind(fd, &sa4.sa, SALEN(sa4.sa)) == -1) {
 922                 logger(mesh, MESHLINK_ERROR, "Error binding to IPv4 multicast socket: %s", strerror(errno));
 923         } else {
 924                 io_add(&mesh->loop, &mesh->discovery.sockets[0], mdns_io_handler, &mesh->discovery.sockets[0], fd, IO_READ);
 925         }
 926
 927         sockaddr_t sa6 = {
 928                 .in6.sin6_family = AF_INET6,
 929                 .in6.sin6_port = ntohs(5353),
 930         };
 931         fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
 932
 933         if(fd == -1) {
 934                 logger(mesh, MESHLINK_ERROR, "Error creating IPv6 socket: %s", strerror(errno));
 935         }
 936
 937         setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 938         setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &one, sizeof(one));
 939         setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
 940         setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
 941         setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
 942         setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
 943
 944         if(bind(fd, &sa6.sa, SALEN(sa6.sa)) == -1) {
 945                 logger(mesh, MESHLINK_ERROR, "Error binding to IPv4 multicast socket: %s", strerror(errno));
 946         } else {
 947                 io_add(&mesh->loop, &mesh->discovery.sockets[1], mdns_io_handler, &mesh->discovery.sockets[1], fd, IO_READ);
 948         }
 949
 950 #if defined(__linux)
 951         int sock = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
 952
 953         if(sock != -1) {
 954                 struct sockaddr_nl sa;
 955                 memset(&sa, 0, sizeof(sa));
 956                 sa.nl_family = AF_NETLINK;
 957                 sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV6_IFADDR;
 958
 959                 if(bind(sock, (struct sockaddr *)&sa, sizeof(sa)) != -1) {
 960                         io_add(&mesh->loop, &mesh->discovery.pfroute_io, netlink_io_handler, NULL, sock, IO_READ);
 961                         netlink_getlink(sock);
 962                 } else {
 963                         logger(mesh, MESHLINK_WARNING, "Could not bind AF_NETLINK socket: %s", strerror(errno));
 964                         scan_ifaddrs(mesh);
 965                 }
 966         } else {
 967                 logger(mesh, MESHLINK_WARNING, "Could not open AF_NETLINK socket: %s", strerror(errno));
 968                 scan_ifaddrs(mesh);
 969         }
 970
 971 #elif defined(__APPLE__)
 972         pthread_create(&mesh->discovery.thread, NULL, network_change_handler, mesh);
 973         // TODO: Do we need to wait for the thread to start succesfully?
 974         scan_ifaddrs(mesh);
 975 #elif defined(RTM_NEWADDR)
 976         int sock = socket(PF_ROUTE, SOCK_RAW, AF_UNSPEC);
 977
 978         if(sock != -1) {
 979                 io_add(&mesh->loop, &mesh->discovery.pfroute_io, pfroute_io_handler, NULL, sock, IO_READ);
 980         } else {
 981                 logger(mesh, MESHLINK_WARNING, "Could not open PF_ROUTE socket: %s", strerror(errno));
 982         }
 983
 984         scan_ifaddrs(mesh);
 985 #endif
 986
 987         return true;
 988 }
 989
 990 void discovery_stop(meshlink_handle_t *mesh) {
 991         logger(mesh, MESHLINK_DEBUG, "discovery_stop called\n");
 992
 993         assert(mesh);
 994
 995         free(mesh->discovery.ifaces);
 996         free(mesh->discovery.addresses);
 997         mesh->discovery.ifaces = NULL;
 998         mesh->discovery.addresses = NULL;
 999         mesh->discovery.iface_count = 0;
1000         mesh->discovery.address_count = 0;
1001
1002 #if defined(__APPLE__)
1003
1004         if(mesh->discovery.runloop) {
1005                 CFRunLoopStop(mesh->discovery.runloop);
1006                 pthread_join(mesh->discovery.thread, NULL);
1007         }
1008
1009 #endif
1010
1011         if(mesh->discovery.pfroute_io.cb) {
1012                 close(mesh->discovery.pfroute_io.fd);
1013                 io_del(&mesh->loop, &mesh->discovery.pfroute_io);
1014         }
1015
1016         for(int i = 0; i < 2; i++) {
1017                 if(mesh->discovery.sockets[i].cb) {
1018                         close(mesh->discovery.sockets[i].fd);
1019                         io_del(&mesh->loop, &mesh->discovery.sockets[i]);
1020                 }
1021         }
1022 }
1023
1024 void discovery_refresh(meshlink_handle_t *mesh) {
1025         for(int i = 0; i < mesh->discovery.address_count; i++) {
1026                 if(mesh->discovery.addresses[i].up) {
1027                         send_mdns_packet(mesh, &mesh->discovery.addresses[i]);
1028                 }
1029         }
1030 }