/*
 * Copyright (c)2013-2020 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: 2024-01-01
 *
 * 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_PATH_HPP
#define ZT_PATH_HPP

#include <cstdint>
#include <cstring>
#include <cstdlib>

#include <stdexcept>
#include <algorithm>

#include "Constants.hpp"
#include "InetAddress.hpp"
#include "SharedPtr.hpp"
#include "AtomicCounter.hpp"
#include "Utils.hpp"
#include "Mutex.hpp"

namespace ZeroTier {

class RuntimeEnvironment;

/**
 * A path across the physical network
 */
class Path
{
	friend class SharedPtr<Path>;

public:
	/**
	 * Efficient unique key for paths in a Hashtable
	 */
	class HashKey
	{
	public:
		ZT_ALWAYS_INLINE HashKey() {}
		ZT_ALWAYS_INLINE HashKey(const int64_t l,const InetAddress &r)
		{
			if (r.ss_family == AF_INET) {
				_k[0] = (uint64_t)reinterpret_cast<const struct sockaddr_in *>(&r)->sin_addr.s_addr;
				_k[1] = (uint64_t)reinterpret_cast<const struct sockaddr_in *>(&r)->sin_port;
				_k[2] = (uint64_t)l;
			} else if (r.ss_family == AF_INET6) {
				memcpy(_k,reinterpret_cast<const struct sockaddr_in6 *>(&r)->sin6_addr.s6_addr,16);
				_k[2] = ((uint64_t)reinterpret_cast<const struct sockaddr_in6 *>(&r)->sin6_port << 32) ^ (uint64_t)l;
			} else {
				memcpy(_k,&r,std::min(sizeof(_k),sizeof(InetAddress)));
				_k[2] += (uint64_t)l;
			}
		}

		ZT_ALWAYS_INLINE unsigned long hashCode() const { return (unsigned long)(_k[0] + _k[1] + _k[2]); }

		ZT_ALWAYS_INLINE bool operator==(const HashKey &k) const { return ( (_k[0] == k._k[0]) && (_k[1] == k._k[1]) && (_k[2] == k._k[2]) ); }
		ZT_ALWAYS_INLINE bool operator!=(const HashKey &k) const { return (!(*this == k)); }

	private:
		uint64_t _k[3];
	};

	ZT_ALWAYS_INLINE Path(const int64_t l,const InetAddress &r) :
		_localSocket(l),
		_lastIn(0),
		_lastOut(0),
		_addr(r),
		__refCount()
	{
	}

	/**
	 * Send a packet via this path (last out time is also updated)
	 *
	 * @param RR Runtime environment
	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
	 * @param data Packet data
	 * @param len Packet length
	 * @param now Current time
	 * @return True if transport reported success
	 */
	bool send(const RuntimeEnvironment *RR,void *tPtr,const void *data,unsigned int len,int64_t now);

	/**
	 * Explicitly update last sent time
	 *
	 * @param t Time of send
	 */
	ZT_ALWAYS_INLINE void sent(const int64_t t) { _lastOut = t; }

	/**
	 * Called when a packet is received from this remote path, regardless of content
	 *
	 * @param t Time of receive
	 */
	ZT_ALWAYS_INLINE void received(const int64_t t) { _lastIn = t; }

	/**
	 * Check path aliveness
	 *
	 * @param now Current time
	 */
	ZT_ALWAYS_INLINE bool alive(const int64_t now) const { return ((now - _lastIn) < ZT_PATH_ALIVE_TIMEOUT); }

	/**
	 * Check if path is considered active
	 *
	 * @param now Current time
	 */
	ZT_ALWAYS_INLINE bool active(const int64_t now) const { return ((now - _lastIn) < ZT_PATH_ACTIVITY_TIMEOUT); }

	/**
	 * @return Physical address
	 */
	ZT_ALWAYS_INLINE const InetAddress &address() const { return _addr; }

	/**
	 * @return Local socket as specified by external code
	 */
	ZT_ALWAYS_INLINE int64_t localSocket() const { return _localSocket; }

	/**
	 * @return Last time we received anything
	 */
	ZT_ALWAYS_INLINE int64_t lastIn() const { return _lastIn; }

	/**
	 * @return Last time we sent something
	 */
	ZT_ALWAYS_INLINE int64_t lastOut() const { return _lastOut; }

	/**
	 * Check whether this address is valid for a ZeroTier path
	 *
	 * This checks the address type and scope against address types and scopes
	 * that we currently support for ZeroTier communication.
	 *
	 * @param a Address to check
	 * @return True if address is good for ZeroTier path use
	 */
	static bool isAddressValidForPath(const InetAddress &a);

private:
	int64_t _localSocket;
	int64_t _lastIn;
	int64_t _lastOut;
	InetAddress _addr;
	AtomicCounter __refCount;
};

} // namespace ZeroTier

#endif