/* 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 . * */ #include "LAN_discovery.h" #define MAX_INTERFACES 16 #ifdef __linux /* Get the first working broadcast address that's not from "lo". * * return higher than 0 on success. * return 0 on error. */ static uint32_t get_broadcast(void) { /* Not sure how many platforms this will run on, * so it's wrapped in __linux for now. */ struct sockaddr_in *sock_holder = NULL; struct ifreq i_faces[MAX_INTERFACES]; struct ifconf ifconf; int count = 0; int sock = 0; int i = 0; /* Configure ifconf for the ioctl call. */ if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) { return 0; } memset(i_faces, 0, sizeof(struct ifreq) * MAX_INTERFACES); ifconf.ifc_buf = (char *)i_faces; ifconf.ifc_len = sizeof(i_faces); count = ifconf.ifc_len / sizeof(struct ifreq); if (ioctl(sock, SIOCGIFCONF, &ifconf) < 0) { return 0; } for (i = 0; i < count; i++) { /* Skip the loopback interface, as it's useless. */ if (strcmp(i_faces[i].ifr_name, "lo") != 0) { if (ioctl(sock, SIOCGIFBRDADDR, &i_faces[i]) < 0) { return 0; } /* Just to clarify where we're getting the values from. */ sock_holder = (struct sockaddr_in *)&i_faces[i].ifr_broadaddr; break; } } close(sock); if (sock_holder == NULL) { return 0; } return sock_holder->sin_addr.s_addr; } #endif /* Return the broadcast ip. */ static IP broadcast_ip(void) { IP ip; #ifdef __linux ip.uint32 = get_broadcast(); if (ip.uint32 == 0) ip.uint32 = ~0; /* Error occured, but try anyway? */ #else ip.uint32 = ~0; #endif return ip; } /* return 0 if ip is a LAN ip. * return -1 if it is not. */ static int LAN_ip(IP ip) { if (ip.uint8[0] == 127) /* Loopback. */ return 0; if (ip.uint8[0] == 10) /* 10.0.0.0 to 10.255.255.255 range. */ return 0; if (ip.uint8[0] == 172 && ip.uint8[1] >= 16 && ip.uint8[1] <= 31) /* 172.16.0.0 to 172.31.255.255 range. */ return 0; if (ip.uint8[0] == 192 && ip.uint8[1] == 168) /* 192.168.0.0 to 192.168.255.255 range. */ return 0; if (ip.uint8[0] == 169 && ip.uint8[1] == 254 && ip.uint8[2] != 0 && ip.uint8[2] != 255)/* 169.254.1.0 to 169.254.254.255 range. */ 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; memcpy(data + 1, c->self_public_key, crypto_box_PUBLICKEYBYTES); IP_Port ip_port = {{broadcast_ip(), port, 0}}; return sendpacket(c->lossless_udp->net->sock, ip_port, data, 1 + crypto_box_PUBLICKEYBYTES); } void LANdiscovery_init(DHT *dht) { networking_registerhandler(dht->c->lossless_udp->net, NET_PACKET_LAN_DISCOVERY, &handle_LANdiscovery, dht); }