/* * ZeroTier One - Network Virtualization Everywhere * Copyright (C) 2011-2016 ZeroTier, Inc. https://www.zerotier.com/ * * This program 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. * * This program 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 this program. If not, see . */ #include "NeighborDiscovery.hpp" #include "OSUtils.hpp" #include "../include/ZeroTierOne.h" #include namespace ZeroTier { uint16_t calc_checksum (uint16_t *addr, int len) { int count = len; register uint32_t sum = 0; uint16_t answer = 0; // Sum up 2-byte values until none or only one byte left. while (count > 1) { sum += *(addr++); count -= 2; } // Add left-over byte, if any. if (count > 0) { sum += *(uint8_t *) addr; } // Fold 32-bit sum into 16 bits; we lose information by doing this, // increasing the chances of a collision. // sum = (lower 16 bits) + (upper 16 bits shifted right 16 bits) while (sum >> 16) { sum = (sum & 0xffff) + (sum >> 16); } // Checksum is one's compliment of sum. answer = ~sum; return (answer); } struct _pseudo_header { uint8_t sourceAddr[16]; uint8_t targetAddr[16]; uint32_t length; uint8_t zeros[3]; uint8_t next; // 58 }; struct _option { _option(int optionType) : type(optionType) , length(8) { memset(mac, 0, sizeof(mac)); } uint8_t type; uint8_t length; uint8_t mac[6]; }; struct _neighbor_solicitation { _neighbor_solicitation() : type(135) , code(0) , checksum(0) , option(1) { memset(&reserved, 0, sizeof(reserved)); memset(target, 0, sizeof(target)); } void calculateChecksum(const sockaddr_storage &sourceIp, const sockaddr_storage &destIp) { _pseudo_header ph; memset(&ph, 0, sizeof(_pseudo_header)); const sockaddr_in6 *src = (const sockaddr_in6*)&sourceIp; const sockaddr_in6 *dest = (const sockaddr_in6*)&destIp; memcpy(ph.sourceAddr, &src->sin6_addr, sizeof(struct in6_addr)); memcpy(ph.targetAddr, &dest->sin6_addr, sizeof(struct in6_addr)); ph.next = 58; ph.length = htonl(sizeof(_neighbor_solicitation)); size_t len = sizeof(_pseudo_header) + sizeof(_neighbor_solicitation); uint8_t *tmp = (uint8_t*)malloc(len); memcpy(tmp, &ph, sizeof(_pseudo_header)); memcpy(tmp+sizeof(_pseudo_header), this, sizeof(_neighbor_solicitation)); checksum = calc_checksum((uint16_t*)tmp, len); free(tmp); tmp = NULL; } uint8_t type; // 135 uint8_t code; // 0 uint16_t checksum; uint32_t reserved; uint8_t target[16]; _option option; }; struct _neighbor_advertisement { _neighbor_advertisement() : type(136) , code(0) , checksum(0) , rso(0x40) , option(2) { memset(padding, 0, sizeof(padding)); memset(target, 0, sizeof(target)); } void calculateChecksum(const sockaddr_storage &sourceIp, const sockaddr_storage &destIp) { _pseudo_header ph; memset(&ph, 0, sizeof(_pseudo_header)); const sockaddr_in6 *src = (const sockaddr_in6*)&sourceIp; const sockaddr_in6 *dest = (const sockaddr_in6*)&destIp; memcpy(ph.sourceAddr, &src->sin6_addr, sizeof(struct in6_addr)); memcpy(ph.targetAddr, &dest->sin6_addr, sizeof(struct in6_addr)); ph.next = 58; ph.length = htonl(sizeof(_neighbor_advertisement)); size_t len = sizeof(_pseudo_header) + sizeof(_neighbor_advertisement); uint8_t *tmp = (uint8_t*)malloc(len); memcpy(tmp, &ph, sizeof(_pseudo_header)); memcpy(tmp+sizeof(_pseudo_header), this, sizeof(_neighbor_advertisement)); checksum = calc_checksum((uint16_t*)tmp, len); free(tmp); tmp = NULL; } uint8_t type; // 136 uint8_t code; // 0 uint16_t checksum; uint8_t rso; uint8_t padding[3]; uint8_t target[16]; _option option; }; NeighborDiscovery::NeighborDiscovery() : _cache(256) , _lastCleaned(OSUtils::now()) {} void NeighborDiscovery::addLocal(const sockaddr_storage &address, const MAC &mac) { _NDEntry &e = _cache[InetAddress(address)]; e.lastQuerySent = 0; e.lastResponseReceived = 0; e.mac = mac; e.local = true; } void NeighborDiscovery::remove(const sockaddr_storage &address) { _cache.erase(InetAddress(address)); } sockaddr_storage NeighborDiscovery::processIncomingND(const uint8_t *nd, unsigned int len, const sockaddr_storage &localIp, uint8_t *response, unsigned int &responseLen, MAC &responseDest) { assert(sizeof(_neighbor_solicitation) == 28); assert(sizeof(_neighbor_advertisement) == 32); const uint64_t now = OSUtils::now(); sockaddr_storage ip = ZT_SOCKADDR_NULL; if (len >= sizeof(_neighbor_solicitation) && nd[0] == 0x87) { // respond to Neighbor Solicitation request for local address _neighbor_solicitation solicitation; memcpy(&solicitation, nd, len); InetAddress targetAddress(solicitation.target, 16, 0); _NDEntry *targetEntry = _cache.get(targetAddress); if (targetEntry && targetEntry->local) { _neighbor_advertisement adv; targetEntry->mac.copyTo(adv.option.mac, 6); memcpy(adv.target, solicitation.target, 16); adv.calculateChecksum(localIp, targetAddress); memcpy(response, &adv, sizeof(_neighbor_advertisement)); responseLen = sizeof(_neighbor_advertisement); responseDest.setTo(solicitation.option.mac, 6); } } else if (len >= sizeof(_neighbor_advertisement) && nd[0] == 0x88) { _neighbor_advertisement adv; memcpy(&adv, nd, len); InetAddress responseAddress(adv.target, 16, 0); _NDEntry *queryEntry = _cache.get(responseAddress); if(queryEntry && !queryEntry->local && (now - queryEntry->lastQuerySent <= ZT_ND_QUERY_MAX_TTL)) { queryEntry->lastResponseReceived = now; queryEntry->mac.setTo(adv.option.mac, 6); ip = responseAddress; } } if ((now - _lastCleaned) >= ZT_ND_EXPIRE) { _lastCleaned = now; Hashtable::Iterator i(_cache); InetAddress *k = NULL; _NDEntry *v = NULL; while (i.next(k, v)) { if(!v->local && (now - v->lastResponseReceived) >= ZT_ND_EXPIRE) { _cache.erase(*k); } } } return ip; } MAC NeighborDiscovery::query(const MAC &localMac, const sockaddr_storage &localIp, const sockaddr_storage &targetIp, uint8_t *query, unsigned int &queryLen, MAC &queryDest) { const uint64_t now = OSUtils::now(); InetAddress localAddress(localIp); localAddress.setPort(0); InetAddress targetAddress(targetIp); targetAddress.setPort(0); _NDEntry &e = _cache[targetAddress]; if ( (e.mac && ((now - e.lastResponseReceived) >= (ZT_ND_EXPIRE / 3))) || (!e.mac && ((now - e.lastQuerySent) >= ZT_ND_QUERY_INTERVAL))) { e.lastQuerySent = now; _neighbor_solicitation ns; memcpy(ns.target, targetAddress.rawIpData(), 16); localMac.copyTo(ns.option.mac, 6); ns.calculateChecksum(localIp, targetIp); if (e.mac) { queryDest = e.mac; } else { queryDest = (uint64_t)0xffffffffffffULL; } } else { queryLen = 0; queryDest.zero(); } return e.mac; } }