/*
 * 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: 2023-01-01
 *
 * 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_MULTICASTER_HPP
#define ZT_MULTICASTER_HPP

#include <stdint.h>
#include <string.h>

#include <map>
#include <vector>

#include "Constants.hpp"
#include "Hashtable.hpp"
#include "Address.hpp"
#include "MAC.hpp"
#include "MulticastGroup.hpp"
#include "Utils.hpp"
#include "Mutex.hpp"
#include "SharedPtr.hpp"
#include "Packet.hpp"

// Size in bits -- this is pretty close to the maximum allowed by the protocol
#define ZT_MULTICAST_BLOOM_FILTER_SIZE_BITS 16384

namespace ZeroTier {

class RuntimeEnvironment;
class CertificateOfMembership;
class Packet;
class Network;

/**
 * Multicast database and outbound multicast logic
 */
class Multicaster
{
public:
	Multicaster(const RuntimeEnvironment *renv);
	~Multicaster();

	/**
	 * Add or update a member in a multicast group
	 *
	 * @param now Current time
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param member New member address
	 */
	ZT_ALWAYS_INLINE void add(const int64_t now,const uint64_t nwid,const MulticastGroup &mg,const Address &member)
	{
		Mutex::Lock l(_groups_l);
		_groups[_K(nwid,mg)].set(member,now);
	}

	/**
	 * Add multiple addresses from a binary array of 5-byte address fields
	 *
	 * It's up to the caller to check bounds on the array before calling this.
	 *
	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
	 * @param now Current time
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param addresses Raw binary addresses in big-endian format, as a series of 5-byte fields
	 * @param count Number of addresses
	 * @param totalKnown Total number of known addresses as reported by peer
	 */
	ZT_ALWAYS_INLINE void addMultiple(const int64_t now,const uint64_t nwid,const MulticastGroup &mg,const void *addresses,unsigned int count,const unsigned int totalKnown)
	{
		Mutex::Lock l(_groups_l);
		const uint8_t *a = (const uint8_t *)addresses;
		Hashtable< Address,int64_t > &members = _groups[_K(nwid,mg)];
		while (count--) {
			members.set(Address(a,ZT_ADDRESS_LENGTH),now);
			a += ZT_ADDRESS_LENGTH;
		}
	}

	/**
	 * Remove a multicast group member (if present)
	 *
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param member Member to unsubscribe
	 */
	ZT_ALWAYS_INLINE void remove(const uint64_t nwid,const MulticastGroup &mg,const Address &member)
	{
		Mutex::Lock l(_groups_l);
		const _K gk(nwid,mg);
		Hashtable< Address,int64_t > *const members = _groups.get(gk);
		if (members) {
			members->erase(member);
			if (members->empty())
				_groups.erase(gk);
		}
	}

	/**
	 * Iterate over members of a multicast group until function returns false
	 *
	 * Iteration order is in inverse order of most recent receipt of a LIKE
	 * for a given membership.
	 *
	 * @param nwid Network ID
	 * @param mg Multicast group
	 * @param func f(Address)
	 * @return Total number of known members (regardless of when function aborted)
	 */
	template<typename F>
	ZT_ALWAYS_INLINE unsigned long eachMember(const uint64_t nwid,const MulticastGroup &mg,F func) const
	{
		std::vector< std::pair<int64_t,Address> > sortedByTime;
		Mutex::Lock l(_groups_l);
		_getMembersByTime(nwid,mg,sortedByTime);
		std::sort(sortedByTime.begin(),sortedByTime.end());
		for(std::vector< std::pair<int64_t,Address> >::const_reverse_iterator i(sortedByTime.begin());i!=sortedByTime.end();++i) {
			if (!func(i->second))
				break;
		}
		return sortedByTime.size();
	}

	/**
	 * Send a multicast
	 *
	 * @param tPtr Thread pointer to be handed through to any callbacks called as a result of this call
	 * @param now Current time
	 * @param network Network
	 * @param mg Multicast group
	 * @param src Source Ethernet MAC address or NULL to skip in packet and compute from ZT address (non-bridged mode)
	 * @param etherType Ethernet frame type
	 * @param existingBloomMultiplier Existing bloom filter multiplier or 0 if none
	 * @param existingBloom Existing bloom filter or NULL if none
	 * @param data Packet data
	 * @param len Length of packet data
	 */
	void send(
		void *tPtr,
		int64_t now,
		const SharedPtr<Network> &network,
		const MulticastGroup &mg,
		const MAC &src,
		unsigned int etherType,
		const unsigned int existingBloomMultiplier,
		const uint8_t existingBloom[ZT_MULTICAST_BLOOM_FILTER_SIZE_BITS / 8],
		const void *const data,
		unsigned int len);

	/**
	 * Clean up database
	 *
	 * @param RR Runtime environment
	 * @param now Current time
	 */
	void clean(int64_t now);

private:
	ZT_ALWAYS_INLINE void _getMembersByTime(const uint64_t nwid,const MulticastGroup &mg,std::vector< std::pair<int64_t,Address> > &byTime)
	{
		// assumes _groups_l is locked
		const _K gk(nwid,mg);
		const Hashtable< Address,int64_t > *const members = _groups.get(gk);
		if (members) {
			byTime.reserve(members->size());
			{
				Hashtable< Address,int64_t >::Iterator mi(*const_cast<Hashtable< Address,int64_t > *>(members));
				Address *mik = nullptr;
				int64_t *miv = nullptr;
				while (mi.next(mik,miv))
					byTime.push_back(std::pair<int64_t,Address>(*miv,*mik));
			}
		}
	}

	struct _K
	{
		uint64_t nwid;
		MulticastGroup mg;

		ZT_ALWAYS_INLINE _K() : nwid(0),mg() {}
		ZT_ALWAYS_INLINE _K(const uint64_t n,const MulticastGroup &g) : nwid(n),mg(g) {}
		ZT_ALWAYS_INLINE bool operator==(const _K &k) const { return ((nwid == k.nwid)&&(mg == k.mg)); }
		ZT_ALWAYS_INLINE bool operator!=(const _K &k) const { return ((nwid != k.nwid)||(mg != k.mg)); }
		ZT_ALWAYS_INLINE unsigned long hashCode() const { return (mg.hashCode() ^ (unsigned long)(nwid ^ (nwid >> 32))); }
	};

	/*
		 * Multicast frame:
		 *   <[8] 64-bit network ID>
		 *   <[1] flags>
		 *  [<[...] network certificate of membership (DEPRECATED)>]
		 *  [<[4] 32-bit implicit gather limit (DEPRECATED)>]
		 *  [<[5] ZeroTier address of originating sender (including w/0x08)>]
		 *  [<[2] 16-bit bloom filter multiplier>]
		 *  [<[2] 16-bit length of propagation bloom filter in bytes]
		 *  [<[...] propagation bloom filter>]
		 *  [<[6] source MAC>]
		 *   <[6] destination MAC (multicast address)>
		 *   <[4] 32-bit multicast ADI (multicast address extension)>
		 *   <[2] 16-bit ethertype>
		 *   <[...] ethernet payload>
		 *  [<[2] 16-bit length of signature>]
		 *  [<[...] signature (algorithm depends on sender identity)>]
	 */

	struct _OM
	{
		uint64_t nwid;
		MAC src;
		MulticastGroup mg;
		unsigned int etherType;
		unsigned int dataSize;
		unsigned int bloomFilterMultiplier;
		uint8_t bloomFilter[ZT_MULTICAST_BLOOM_FILTER_SIZE_BITS / 8];
		uint8_t data[ZT_MAX_MTU];
		Mutex lock;
	};

	const RuntimeEnvironment *const RR;

	_OM _txQueue[ZT_TX_QUEUE_SIZE];
	unsigned int _txQueuePtr;
	Mutex _txQueue_l;

	Hashtable< _K,Hashtable< Address,int64_t > > _groups;
	Mutex _groups_l;
};

} // namespace ZeroTier

#endif