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121 lines
3.8 KiB
121 lines
3.8 KiB
/* |
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* Copyright (c)2019 ZeroTier, Inc. |
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* |
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* Use of this software is governed by the Business Source License included |
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* in the LICENSE.TXT file in the project's root directory. |
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* |
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* Change Date: 2025-01-01 |
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* |
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* On the date above, in accordance with the Business Source License, use |
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* of this software will be governed by version 2.0 of the Apache License. |
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*/ |
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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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