mirror of
https://github.com/zerotier/ZeroTierOne.git
synced 2024-11-03 04:00:19 -08:00
144 lines
4.3 KiB
C++
144 lines
4.3 KiB
C++
/*
|
|
* Copyright (c)2019 ZeroTier, Inc.
|
|
*
|
|
* Use of this software is governed by the Business Source License included
|
|
* in the LICENSE.TXT file in the project's root directory.
|
|
*
|
|
* Change Date: 2026-01-01
|
|
*
|
|
* On the date above, in accordance with the Business Source License, use
|
|
* of this software will be governed by version 2.0 of the Apache License.
|
|
*/
|
|
/****/
|
|
|
|
#ifndef ZT_ARP_HPP
|
|
#define ZT_ARP_HPP
|
|
|
|
#include <stdint.h>
|
|
|
|
#include <utility>
|
|
|
|
#include "../node/Constants.hpp"
|
|
#include "../node/Hashtable.hpp"
|
|
#include "../node/MAC.hpp"
|
|
|
|
/**
|
|
* Maximum possible ARP length
|
|
*
|
|
* ARPs are 28 bytes in length, but specify a 128 byte buffer since
|
|
* some weird extensions we may support in the future can pad them
|
|
* out to as long as 72 bytes.
|
|
*/
|
|
#define ZT_ARP_BUF_LENGTH 128
|
|
|
|
/**
|
|
* Minimum permitted interval between sending ARP queries for a given IP
|
|
*/
|
|
#define ZT_ARP_QUERY_INTERVAL 2000
|
|
|
|
/**
|
|
* Maximum time between query and response, otherwise responses are discarded to prevent poisoning
|
|
*/
|
|
#define ZT_ARP_QUERY_MAX_TTL 5000
|
|
|
|
/**
|
|
* ARP expiration time
|
|
*/
|
|
#define ZT_ARP_EXPIRE 600000
|
|
|
|
namespace ZeroTier {
|
|
|
|
/**
|
|
* ARP cache and resolver
|
|
*
|
|
* To implement ARP:
|
|
*
|
|
* (1) Call processIncomingArp() on all ARP packets received and then always
|
|
* check responseLen after calling. If it is non-zero, send the contents
|
|
* of response to responseDest.
|
|
*
|
|
* (2) Call query() to look up IP addresses, and then check queryLen. If it
|
|
* is non-zero, send the contents of query to queryDest (usually broadcast).
|
|
*
|
|
* Note that either of these functions can technically generate a response or
|
|
* a query at any time, so their result parameters for sending ARPs should
|
|
* always be checked.
|
|
*
|
|
* This class is not thread-safe and must be guarded if used in multi-threaded
|
|
* code.
|
|
*/
|
|
class Arp
|
|
{
|
|
public:
|
|
Arp();
|
|
|
|
/**
|
|
* Set a local IP entry that we should respond to ARPs for
|
|
*
|
|
* @param mac Our local MAC address
|
|
* @param ip IP in big-endian byte order (sin_addr.s_addr)
|
|
*/
|
|
void addLocal(uint32_t ip,const MAC &mac);
|
|
|
|
/**
|
|
* Delete a local IP entry or a cached ARP entry
|
|
*
|
|
* @param ip IP in big-endian byte order (sin_addr.s_addr)
|
|
*/
|
|
void remove(uint32_t ip);
|
|
|
|
/**
|
|
* Process ARP packets
|
|
*
|
|
* For ARP queries, a response is generated and responseLen is set to its
|
|
* frame payload length in bytes.
|
|
*
|
|
* For ARP responses, the cache is populated and the IP address entry that
|
|
* was learned is returned.
|
|
*
|
|
* @param arp ARP frame data
|
|
* @param len Length of ARP frame (usually 28)
|
|
* @param response Response buffer -- MUST be a minimum of ZT_ARP_BUF_LENGTH in size
|
|
* @param responseLen Response length, or set to 0 if no response
|
|
* @param responseDest Destination of response, or set to null if no response
|
|
* @return IP address learned or 0 if no new IPs in cache
|
|
*/
|
|
uint32_t processIncomingArp(const void *arp,unsigned int len,void *response,unsigned int &responseLen,MAC &responseDest);
|
|
|
|
/**
|
|
* Get the MAC corresponding to an IP, generating a query if needed
|
|
*
|
|
* This returns a MAC for a remote IP. The local MAC is returned for local
|
|
* IPs as well. It may also generate a query if the IP is not known or the
|
|
* entry needs to be refreshed. In this case queryLen will be set to a
|
|
* non-zero value, so this should always be checked on return even if the
|
|
* MAC returned is non-null.
|
|
*
|
|
* @param localMac Local MAC address of host interface
|
|
* @param localIp Local IP address of host interface
|
|
* @param targetIp IP to look up
|
|
* @param query Buffer for generated query -- MUST be a minimum of ZT_ARP_BUF_LENGTH in size
|
|
* @param queryLen Length of generated query, or set to 0 if no query generated
|
|
* @param queryDest Destination of query, or set to null if no query generated
|
|
* @return MAC or 0 if no cached entry for this IP
|
|
*/
|
|
MAC query(const MAC &localMac,uint32_t localIp,uint32_t targetIp,void *query,unsigned int &queryLen,MAC &queryDest);
|
|
|
|
private:
|
|
struct _ArpEntry
|
|
{
|
|
_ArpEntry() : lastQuerySent(0),lastResponseReceived(0),mac(),local(false) {}
|
|
uint64_t lastQuerySent; // Time last query was sent or 0 for local IP
|
|
uint64_t lastResponseReceived; // Time of last ARP response or 0 for local IP
|
|
MAC mac; // MAC address of device responsible for IP or null if not known yet
|
|
bool local; // True if this is a local ARP entry
|
|
};
|
|
|
|
Hashtable< uint32_t,_ArpEntry > _cache;
|
|
uint64_t _lastCleaned;
|
|
};
|
|
|
|
} // namespace ZeroTier
|
|
|
|
#endif
|