mirror of
https://github.com/didyouexpectthat/zerotierone.git
synced 2024-09-20 12:50:20 -07:00
127 lines
4.2 KiB
C++
127 lines
4.2 KiB
C++
/*
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* ZeroTier One - Network Virtualization Everywhere
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* Copyright (C) 2011-2016 ZeroTier, Inc. https://www.zerotier.com/
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include "Arp.hpp"
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#include "OSUtils.hpp"
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namespace ZeroTier {
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static const uint8_t ARP_REQUEST_HEADER[8] = { 0x00,0x01,0x08,0x00,0x06,0x04,0x00,0x01 };
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static const uint8_t ARP_RESPONSE_HEADER[8] = { 0x00,0x01,0x08,0x00,0x06,0x04,0x00,0x02 };
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Arp::Arp() :
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_cache(256),
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_lastCleaned(OSUtils::now())
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{
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}
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void Arp::addLocal(uint32_t ip,const MAC &mac)
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{
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_ArpEntry &e = _cache[ip];
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e.lastQuerySent = 0; // local IP
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e.lastResponseReceived = 0; // local IP
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e.mac = mac;
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e.local = true;
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}
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void Arp::remove(uint32_t ip)
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{
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_cache.erase(ip);
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}
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uint32_t Arp::processIncomingArp(const void *arp,unsigned int len,void *response,unsigned int &responseLen,MAC &responseDest)
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{
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const uint64_t now = OSUtils::now();
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uint32_t ip = 0;
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responseLen = 0;
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responseDest.zero();
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if (len >= 28) {
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if (!memcmp(arp,ARP_REQUEST_HEADER,8)) {
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// Respond to ARP requests for locally-known IPs
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_ArpEntry *targetEntry = _cache.get(reinterpret_cast<const uint32_t *>(arp)[6]);
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if ((targetEntry)&&(targetEntry->local)) {
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memcpy(response,ARP_RESPONSE_HEADER,8);
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targetEntry->mac.copyTo(reinterpret_cast<uint8_t *>(response) + 8,6);
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memcpy(reinterpret_cast<uint8_t *>(response) + 14,reinterpret_cast<const uint8_t *>(arp) + 24,4);
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memcpy(reinterpret_cast<uint8_t *>(response) + 18,reinterpret_cast<const uint8_t *>(arp) + 8,10);
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responseLen = 28;
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responseDest.setTo(reinterpret_cast<const uint8_t *>(arp) + 8,6);
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}
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} else if (!memcmp(arp,ARP_RESPONSE_HEADER,8)) {
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// Learn cache entries for remote IPs from relevant ARP replies
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uint32_t responseIp = 0;
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memcpy(&responseIp,reinterpret_cast<const uint8_t *>(arp) + 14,4);
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_ArpEntry *queryEntry = _cache.get(responseIp);
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if ((queryEntry)&&(!queryEntry->local)&&((now - queryEntry->lastQuerySent) <= ZT_ARP_QUERY_MAX_TTL)) {
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queryEntry->lastResponseReceived = now;
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queryEntry->mac.setTo(reinterpret_cast<const uint8_t *>(arp) + 8,6);
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ip = responseIp;
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}
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}
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}
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if ((now - _lastCleaned) >= ZT_ARP_EXPIRE) {
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_lastCleaned = now;
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Hashtable< uint32_t,_ArpEntry >::Iterator i(_cache);
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uint32_t *k = (uint32_t *)0;
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_ArpEntry *v = (_ArpEntry *)0;
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while (i.next(k,v)) {
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if ((!v->local)&&((now - v->lastResponseReceived) >= ZT_ARP_EXPIRE))
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_cache.erase(*k);
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}
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}
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return ip;
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}
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MAC Arp::query(const MAC &localMac,uint32_t localIp,uint32_t targetIp,void *query,unsigned int &queryLen,MAC &queryDest)
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{
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const uint64_t now = OSUtils::now();
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_ArpEntry &e = _cache[targetIp];
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if ( ((e.mac)&&((now - e.lastResponseReceived) >= (ZT_ARP_EXPIRE / 3))) ||
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((!e.mac)&&((now - e.lastQuerySent) >= ZT_ARP_QUERY_INTERVAL)) ) {
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e.lastQuerySent = now;
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uint8_t *q = reinterpret_cast<uint8_t *>(query);
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memcpy(q,ARP_REQUEST_HEADER,8); q += 8; // ARP request header information, always the same
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localMac.copyTo(q,6); q += 6; // sending host MAC address
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memcpy(q,&localIp,4); q += 4; // sending host IP (IP already in big-endian byte order)
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memset(q,0,6); q += 6; // sending zeros for target MAC address as thats what we want to find
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memcpy(q,&targetIp,4); // target IP address for resolution (IP already in big-endian byte order)
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queryLen = 28;
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if (e.mac)
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queryDest = e.mac; // confirmation query, send directly to address holder
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else queryDest = (uint64_t)0xffffffffffffULL; // broadcast query
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} else {
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queryLen = 0;
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queryDest.zero();
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}
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return e.mac;
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}
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} // namespace ZeroTier
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