/* LAN_discovery.c * * LAN discovery implementation. * * Copyright (C) 2013 Tox project All Rights Reserved. * * This file is part of Tox. * * Tox is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * Tox is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with Tox. If not, see . * */ #ifdef HAVE_CONFIG_H #include "config.h" #endif #include "LAN_discovery.h" #include "util.h" #define MAX_INTERFACES 16 #ifdef __linux static int broadcast_count = -1; static IP_Port broadcast_ip_port[MAX_INTERFACES]; static void fetch_broadcast_info(uint16_t port) { /* Not sure how many platforms this will run on, * so it's wrapped in __linux for now. * Definitely won't work like this on Windows... */ broadcast_count = 0; sock_t sock = 0; if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) return; /* Configure ifconf for the ioctl call. */ struct ifreq i_faces[MAX_INTERFACES]; memset(i_faces, 0, sizeof(struct ifreq) * MAX_INTERFACES); struct ifconf ifconf; ifconf.ifc_buf = (char *)i_faces; ifconf.ifc_len = sizeof(i_faces); if (ioctl(sock, SIOCGIFCONF, &ifconf) < 0) { close(sock); return; } /* ifconf.ifc_len is set by the ioctl() to the actual length used; * on usage of the complete array the call should be repeated with * a larger array, not done (640kB and 16 interfaces shall be * enough, for everybody!) */ int i, count = ifconf.ifc_len / sizeof(struct ifreq); for (i = 0; i < count; i++) { /* there are interfaces with are incapable of broadcast */ if (ioctl(sock, SIOCGIFBRDADDR, &i_faces[i]) < 0) continue; /* moot check: only AF_INET returned (backwards compat.) */ if (i_faces[i].ifr_broadaddr.sa_family != AF_INET) continue; struct sockaddr_in *sock4 = (struct sockaddr_in *)&i_faces[i].ifr_broadaddr; if (broadcast_count >= MAX_INTERFACES) return; IP_Port *ip_port = &broadcast_ip_port[broadcast_count]; ip_port->ip.family = AF_INET; ip_port->ip.ip4.in_addr = sock4->sin_addr; ip_port->port = port; broadcast_count++; } close(sock); } /* Send packet to all IPv4 broadcast addresses * * return 1 if sent to at least one broadcast target. * return 0 on failure to find any valid broadcast target. */ static uint32_t send_broadcasts(Networking_Core *net, uint16_t port, uint8_t *data, uint16_t length) { /* fetch only once? on every packet? every X seconds? * old: every packet, new: once */ if (broadcast_count < 0) fetch_broadcast_info(port); if (!broadcast_count) return 0; int i; for (i = 0; i < broadcast_count; i++) sendpacket(net, broadcast_ip_port[i], data, length); return 1; } #endif /* __linux */ /* Return the broadcast ip. */ static IP broadcast_ip(sa_family_t family_socket, sa_family_t family_broadcast) { IP ip; ip_reset(&ip); if (family_socket == AF_INET6) { if (family_broadcast == AF_INET6) { ip.family = AF_INET6; /* FF02::1 is - according to RFC 4291 - multicast all-nodes link-local */ /* FE80::*: MUST be exact, for that we would need to look over all * interfaces and check in which status they are */ ip.ip6.uint8[ 0] = 0xFF; ip.ip6.uint8[ 1] = 0x02; ip.ip6.uint8[15] = 0x01; } else if (family_broadcast == AF_INET) { ip.family = AF_INET6; ip.ip6.uint32[0] = 0; ip.ip6.uint32[1] = 0; ip.ip6.uint32[2] = htonl(0xFFFF); ip.ip6.uint32[3] = INADDR_BROADCAST; } } else if (family_socket == AF_INET) { if (family_broadcast == AF_INET) { ip.family = AF_INET; ip.ip4.uint32 = INADDR_BROADCAST; } } return ip; } /* return 0 if ip is a LAN ip. * return -1 if it is not. */ int LAN_ip(IP ip) { if (ip.family == AF_INET) { IP4 ip4 = ip.ip4; /* Loopback. */ if (ip4.uint8[0] == 127) return 0; /* 10.0.0.0 to 10.255.255.255 range. */ if (ip4.uint8[0] == 10) return 0; /* 172.16.0.0 to 172.31.255.255 range. */ if (ip4.uint8[0] == 172 && ip4.uint8[1] >= 16 && ip4.uint8[1] <= 31) return 0; /* 192.168.0.0 to 192.168.255.255 range. */ if (ip4.uint8[0] == 192 && ip4.uint8[1] == 168) return 0; /* 169.254.1.0 to 169.254.254.255 range. */ if (ip4.uint8[0] == 169 && ip4.uint8[1] == 254 && ip4.uint8[2] != 0 && ip4.uint8[2] != 255) return 0; } else if (ip.family == AF_INET6) { /* autogenerated for each interface: FE80::* (up to FEBF::*) FF02::1 is - according to RFC 4291 - multicast all-nodes link-local */ if (((ip.ip6.uint8[0] == 0xFF) && (ip.ip6.uint8[1] < 3) && (ip.ip6.uint8[15] == 1)) || ((ip.ip6.uint8[0] == 0xFE) && ((ip.ip6.uint8[1] & 0xC0) == 0x80))) return 0; /* embedded IPv4-in-IPv6 */ if (IN6_IS_ADDR_V4MAPPED(&ip.ip6.in6_addr)) { IP ip4; ip4.family = AF_INET; ip4.ip4.uint32 = ip.ip6.uint32[3]; return LAN_ip(ip4); } /* localhost in IPv6 (::1) */ if (IN6_IS_ADDR_LOOPBACK(&ip.ip6.in6_addr)) return 0; } return -1; } static int handle_LANdiscovery(void *object, IP_Port source, uint8_t *packet, uint32_t length) { DHT *dht = object; if (LAN_ip(source.ip) == -1) return 1; if (length != crypto_box_PUBLICKEYBYTES + 1) return 1; DHT_bootstrap(dht, source, packet + 1); return 0; } int send_LANdiscovery(uint16_t port, Net_Crypto *c) { uint8_t data[crypto_box_PUBLICKEYBYTES + 1]; data[0] = NET_PACKET_LAN_DISCOVERY; id_copy(data + 1, c->self_public_key); #ifdef __linux send_broadcasts(c->lossless_udp->net, port, data, 1 + crypto_box_PUBLICKEYBYTES); #endif int res = -1; IP_Port ip_port; ip_port.port = port; /* IPv6 multicast */ if (c->lossless_udp->net->family == AF_INET6) { ip_port.ip = broadcast_ip(AF_INET6, AF_INET6); if (ip_isset(&ip_port.ip)) if (sendpacket(c->lossless_udp->net, ip_port, data, 1 + crypto_box_PUBLICKEYBYTES) > 0) res = 1; } /* IPv4 broadcast (has to be IPv4-in-IPv6 mapping if socket is AF_INET6 */ ip_port.ip = broadcast_ip(c->lossless_udp->net->family, AF_INET); if (ip_isset(&ip_port.ip)) if (sendpacket(c->lossless_udp->net, ip_port, data, 1 + crypto_box_PUBLICKEYBYTES)) res = 1; return res; } void LANdiscovery_init(DHT *dht) { networking_registerhandler(dht->c->lossless_udp->net, NET_PACKET_LAN_DISCOVERY, &handle_LANdiscovery, dht); }