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121 lines
3.7 KiB
121 lines
3.7 KiB
/* This Source Code Form is subject to the terms of the Mozilla Public |
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* License, v. 2.0. If a copy of the MPL was not distributed with this |
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. |
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* |
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* (c) ZeroTier, Inc. |
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* https://www.zerotier.com/ |
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*/ |
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#include "Arp.hpp" |
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#include "OSUtils.hpp" |
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#include <stdio.h> |
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#include <stdlib.h> |
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#include <string.h> |
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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() : _cache(256), _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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} |
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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))) || ((! 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); |
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q += 8; // ARP request header information, always the same |
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localMac.copyTo(q, 6); |
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q += 6; // sending host MAC address |
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memcpy(q, &localIp, 4); |
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q += 4; // sending host IP (IP already in big-endian byte order) |
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memset(q, 0, 6); |
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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 |
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queryDest = (uint64_t)0xffffffffffffULL; // broadcast query |
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} |
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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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