/* (c) Magnus Auvinen. See licence.txt in the root of the distribution for more information. */
/* If you are missing that file, acquire a complete release at teeworlds.com.                */
#ifndef ENGINE_SHARED_NETWORK_H
#define ENGINE_SHARED_NETWORK_H

#include "ringbuffer.h"
#include "huffman.h"

#include <base/math.h>

#include <engine/message.h>

/*

CURRENT:
	packet header: 3 bytes
		unsigned char flags_ack; // 4bit flags, 4bit ack
		unsigned char ack; // 8 bit ack
		unsigned char num_chunks; // 8 bit chunks

		(unsigned char padding[3])	// 24 bit extra in case it's a connection less packet
									// this is to make sure that it's compatible with the
									// old protocol

	chunk header: 2-3 bytes
		unsigned char flags_size; // 2bit flags, 6 bit size
		unsigned char size_seq; // 4bit size, 4bit seq
		(unsigned char seq;) // 8bit seq, if vital flag is set
*/

enum
{
	NETFLAG_ALLOWSTATELESS=1,
	NETSENDFLAG_VITAL=1,
	NETSENDFLAG_CONNLESS=2,
	NETSENDFLAG_FLUSH=4,
	NETSENDFLAG_EXTENDED=8,

	NETSTATE_OFFLINE=0,
	NETSTATE_CONNECTING,
	NETSTATE_ONLINE,

	NETBANTYPE_SOFT=1,
	NETBANTYPE_DROP=2
};


enum
{
	NET_VERSION = 2,

	NET_MAX_PACKETSIZE = 1400,
	NET_MAX_PAYLOAD = NET_MAX_PACKETSIZE-6,
	NET_MAX_CHUNKHEADERSIZE = 5,
	NET_PACKETHEADERSIZE = 3,
	NET_MAX_CLIENTS = 64,
	NET_MAX_CONSOLE_CLIENTS = 4,
	NET_MAX_SEQUENCE = 1<<10,
	NET_SEQUENCE_MASK = NET_MAX_SEQUENCE-1,

	NET_CONNSTATE_OFFLINE=0,
	NET_CONNSTATE_CONNECT=1,
	NET_CONNSTATE_PENDING=2,
	NET_CONNSTATE_ONLINE=3,
	NET_CONNSTATE_ERROR=4,

	NET_PACKETFLAG_CONTROL=1,
	NET_PACKETFLAG_CONNLESS=2,
	NET_PACKETFLAG_RESEND=4,
	NET_PACKETFLAG_COMPRESSION=8,
	// NOT SENT VIA THE NETWORK DIRECTLY:
	NET_PACKETFLAG_EXTENDED=16,

	NET_CHUNKFLAG_VITAL=1,
	NET_CHUNKFLAG_RESEND=2,

	NET_CTRLMSG_KEEPALIVE=0,
	NET_CTRLMSG_CONNECT=1,
	NET_CTRLMSG_CONNECTACCEPT=2,
	NET_CTRLMSG_ACCEPT=3,
	NET_CTRLMSG_CLOSE=4,

	NET_CONN_BUFFERSIZE=1024*32,

	NET_CONNLIMIT_IPS=16,

	NET_ENUM_TERMINATOR
};

typedef int SECURITY_TOKEN;

SECURITY_TOKEN ToSecurityToken(unsigned char *pData);

static const unsigned char SECURITY_TOKEN_MAGIC[] = {'T', 'K', 'E', 'N'};

enum
{
	NET_SECURITY_TOKEN_UNKNOWN = -1,
	NET_SECURITY_TOKEN_UNSUPPORTED = 0,
};

typedef int (*NETFUNC_DELCLIENT)(int ClientID, const char *pReason, void *pUser);
typedef int (*NETFUNC_NEWCLIENT)(int ClientID, void *pUser);
typedef int (*NETFUNC_NEWCLIENT_NOAUTH)(int ClientID, void *pUser);
typedef int (*NETFUNC_CLIENTREJOIN)(int ClientID, void *pUser);

struct CNetChunk
{
	// -1 means that it's a stateless packet
	// 0 on the client means the server
	int m_ClientID;
	NETADDR m_Address; // only used when client_id == -1
	int m_Flags;
	int m_DataSize;
	const void *m_pData;
	// only used if the flags contain NETSENDFLAG_EXTENDED and NETSENDFLAG_CONNLESS
	unsigned char m_aExtraData[4];
};

class CNetChunkHeader
{
public:
	int m_Flags;
	int m_Size;
	int m_Sequence;

	unsigned char *Pack(unsigned char *pData);
	unsigned char *Unpack(unsigned char *pData);
};

class CNetChunkResend
{
public:
	int m_Flags;
	int m_DataSize;
	unsigned char *m_pData;

	int m_Sequence;
	int64 m_LastSendTime;
	int64 m_FirstSendTime;
};

class CNetPacketConstruct
{
public:
	int m_Flags;
	int m_Ack;
	int m_NumChunks;
	int m_DataSize;
	unsigned char m_aChunkData[NET_MAX_PAYLOAD];
	unsigned char m_aExtraData[4];
};


class CNetConnection
{
	// TODO: is this needed because this needs to be aware of
	// the ack sequencing number and is also responible for updating
	// that. this should be fixed.
	friend class CNetRecvUnpacker;
private:
	unsigned short m_Sequence;
	unsigned short m_Ack;
	unsigned short m_PeerAck;
	unsigned m_State;

	int m_Token;
	SECURITY_TOKEN m_SecurityToken;
	int m_RemoteClosed;
	bool m_BlockCloseMsg;
	bool m_UnknownSeq;

	TStaticRingBuffer<CNetChunkResend, NET_CONN_BUFFERSIZE> m_Buffer;

	int64 m_LastUpdateTime;
	int64 m_LastRecvTime;
	int64 m_LastSendTime;

	char m_ErrorString[256];

	CNetPacketConstruct m_Construct;

	NETADDR m_PeerAddr;
	NETSOCKET m_Socket;
	NETSTATS m_Stats;

	//
	void ResetStats();
	void SetError(const char *pString);
	void AckChunks(int Ack);

	int QueueChunkEx(int Flags, int DataSize, const void *pData, int Sequence);
	void SendControl(int ControlMsg, const void *pExtra, int ExtraSize);
	void ResendChunk(CNetChunkResend *pResend);
	void Resend();

	bool HasSecurityToken;

public:
	bool m_TimeoutProtected;
	bool m_TimeoutSituation;

	void Reset(bool Rejoin=false);
	void Init(NETSOCKET Socket, bool BlockCloseMsg);
	int Connect(NETADDR *pAddr);
	void Disconnect(const char *pReason);

	int Update();
	int Flush();

	int Feed(CNetPacketConstruct *pPacket, NETADDR *pAddr, SECURITY_TOKEN SecurityToken = NET_SECURITY_TOKEN_UNSUPPORTED);
	int QueueChunk(int Flags, int DataSize, const void *pData);

	const char *ErrorString();
	void SignalResend();
	int State() const { return m_State; }
	const NETADDR *PeerAddress() const { return &m_PeerAddr; }

	void ResetErrorString() { m_ErrorString[0] = 0; }
	const char *ErrorString() const { return m_ErrorString; }

	// Needed for GotProblems in NetClient
	int64 LastRecvTime() const { return m_LastRecvTime; }
	int64 ConnectTime() const { return m_LastUpdateTime; }

	int AckSequence() const { return m_Ack; }
	int SeqSequence() const { return m_Sequence; }
	int SecurityToken() const { return m_SecurityToken; }
	TStaticRingBuffer<CNetChunkResend, NET_CONN_BUFFERSIZE> *ResendBuffer() { return &m_Buffer; };

	void SetTimedOut(const NETADDR *pAddr, int Sequence, int Ack, SECURITY_TOKEN SecurityToken, TStaticRingBuffer<CNetChunkResend, NET_CONN_BUFFERSIZE> *pResendBuffer);

	// anti spoof
	void DirectInit(NETADDR &Addr, SECURITY_TOKEN SecurityToken);
	void SetUnknownSeq() { m_UnknownSeq = true; }
	void SetSequence(int Sequence) { m_Sequence = Sequence; }
};

class CConsoleNetConnection
{
private:
	int m_State;

	NETADDR m_PeerAddr;
	NETSOCKET m_Socket;

	char m_aBuffer[NET_MAX_PACKETSIZE];
	int m_BufferOffset;

	char m_aErrorString[256];

	bool m_LineEndingDetected;
	char m_aLineEnding[3];

public:
	void Init(NETSOCKET Socket, const NETADDR *pAddr);
	void Disconnect(const char *pReason);

	int State() const { return m_State; }
	const NETADDR *PeerAddress() const { return &m_PeerAddr; }
	const char *ErrorString() const { return m_aErrorString; }

	void Reset();
	int Update();
	int Send(const char *pLine);
	int Recv(char *pLine, int MaxLength);
};

class CNetRecvUnpacker
{
public:
	bool m_Valid;

	NETADDR m_Addr;
	CNetConnection *m_pConnection;
	int m_CurrentChunk;
	int m_ClientID;
	CNetPacketConstruct m_Data;
	unsigned char m_aBuffer[NET_MAX_PACKETSIZE];

	CNetRecvUnpacker() { Clear(); }
	void Clear();
	void Start(const NETADDR *pAddr, CNetConnection *pConnection, int ClientID);
	int FetchChunk(CNetChunk *pChunk);
};

// server side
class CNetServer
{
	struct CSlot
	{
	public:
		CNetConnection m_Connection;
	};

	struct CSpamConn
	{
		NETADDR m_Addr;
		int64 m_Time;
		int m_Conns;
	};

	NETSOCKET m_Socket;
	class CNetBan *m_pNetBan;
	CSlot m_aSlots[NET_MAX_CLIENTS];
	int m_MaxClients;
	int m_MaxClientsPerIP;

	NETFUNC_NEWCLIENT m_pfnNewClient;
	NETFUNC_NEWCLIENT_NOAUTH m_pfnNewClientNoAuth;
	NETFUNC_DELCLIENT m_pfnDelClient;
	NETFUNC_CLIENTREJOIN m_pfnClientRejoin;
	void *m_UserPtr;


	int m_NumConAttempts; // log flooding attacks
	int64 m_TimeNumConAttempts;
	unsigned char m_SecurityTokenSeed[16];

	// vanilla connect flood detection
	bool m_VConnHighLoad;
	int64 m_VConnFirst;
	int m_VConnNum;

	CSpamConn m_aSpamConns[NET_CONNLIMIT_IPS];

	CNetRecvUnpacker m_RecvUnpacker;

	void OnTokenCtrlMsg(NETADDR &Addr, int ControlMsg, const CNetPacketConstruct &Packet);
	void OnPreConnMsg(NETADDR &Addr, CNetPacketConstruct &Packet);
	void OnConnCtrlMsg(NETADDR &Addr, int ClientID, int ControlMsg, const CNetPacketConstruct &Packet);
	bool ClientExists(const NETADDR &Addr) { return GetClientSlot(Addr) != -1; };
	int GetClientSlot(const NETADDR &Addr);
	void SendControl(NETADDR &Addr, int ControlMsg, const void *pExtra, int ExtraSize, SECURITY_TOKEN SecurityToken);

	int TryAcceptClient(NETADDR &Addr, SECURITY_TOKEN SecurityToken, bool VanillaAuth=false);
	int NumClientsWithAddr(NETADDR Addr);
	bool Connlimit(NETADDR Addr);
	void SendMsgs(NETADDR &Addr, const CMsgPacker *Msgs[], int num);

public:
	int SetCallbacks(NETFUNC_NEWCLIENT pfnNewClient, NETFUNC_DELCLIENT pfnDelClient, void *pUser);
	int SetCallbacks(NETFUNC_NEWCLIENT pfnNewClient, NETFUNC_NEWCLIENT_NOAUTH pfnNewClientNoAuth, NETFUNC_CLIENTREJOIN pfnClientRejoin, NETFUNC_DELCLIENT pfnDelClient, void *pUser);

	//
	bool Open(NETADDR BindAddr, class CNetBan *pNetBan, int MaxClients, int MaxClientsPerIP, int Flags);
	int Close();

	//
	int Recv(CNetChunk *pChunk);
	int Send(CNetChunk *pChunk);
	int Update();

	//
	int Drop(int ClientID, const char *pReason);

	// status requests
	const NETADDR *ClientAddr(int ClientID) const { return m_aSlots[ClientID].m_Connection.PeerAddress(); }
	bool HasSecurityToken(int ClientID) const { return m_aSlots[ClientID].m_Connection.SecurityToken() != NET_SECURITY_TOKEN_UNSUPPORTED; }
	NETSOCKET Socket() const { return m_Socket; }
	class CNetBan *NetBan() const { return m_pNetBan; }
	int NetType() const { return m_Socket.type; }
	int MaxClients() const { return m_MaxClients; }

	//
	void SetMaxClientsPerIP(int Max);
	bool SetTimedOut(int ClientID, int OrigID);
	void SetTimeoutProtected(int ClientID);

	int ResetErrorString(int ClientID);
	const char *ErrorString(int ClientID);

	// anti spoof
	SECURITY_TOKEN GetToken(const NETADDR &Addr);
	// vanilla token/gametick shouldn't be negative
	SECURITY_TOKEN GetVanillaToken(const NETADDR &Addr) { return absolute(GetToken(Addr)); }
};

class CNetConsole
{
	struct CSlot
	{
		CConsoleNetConnection m_Connection;
	};

	NETSOCKET m_Socket;
	class CNetBan *m_pNetBan;
	CSlot m_aSlots[NET_MAX_CONSOLE_CLIENTS];

	NETFUNC_NEWCLIENT m_pfnNewClient;
	NETFUNC_DELCLIENT m_pfnDelClient;
	void *m_UserPtr;

	CNetRecvUnpacker m_RecvUnpacker;

public:
	void SetCallbacks(NETFUNC_NEWCLIENT pfnNewClient, NETFUNC_DELCLIENT pfnDelClient, void *pUser);

	//
	bool Open(NETADDR BindAddr, class CNetBan *pNetBan, int Flags);
	int Close();

	//
	int Recv(char *pLine, int MaxLength, int *pClientID = 0);
	int Send(int ClientID, const char *pLine);
	int Update();

	//
	int AcceptClient(NETSOCKET Socket, const NETADDR *pAddr);
	int Drop(int ClientID, const char *pReason);

	// status requests
	const NETADDR *ClientAddr(int ClientID) const { return m_aSlots[ClientID].m_Connection.PeerAddress(); }
	class CNetBan *NetBan() const { return m_pNetBan; }
};



// client side
class CNetClient
{
	CNetConnection m_Connection;
	CNetRecvUnpacker m_RecvUnpacker;
public:
	NETSOCKET m_Socket;
	// openness
	bool Open(NETADDR BindAddr, int Flags);
	int Close();

	// connection state
	int Disconnect(const char *Reason);
	int Connect(NETADDR *Addr);

	// communication
	int Recv(CNetChunk *Chunk);
	int Send(CNetChunk *Chunk);

	// pumping
	int Update();
	int Flush();

	int ResetErrorString();

	// error and state
	int NetType() const { return m_Socket.type; }
	int State();
	int GotProblems();
	const char *ErrorString();

	bool SecurityTokenUnknown() { return m_Connection.SecurityToken() == NET_SECURITY_TOKEN_UNKNOWN; }
};



// TODO: both, fix these. This feels like a junk class for stuff that doesn't fit anywere
class CNetBase
{
	static IOHANDLE ms_DataLogSent;
	static IOHANDLE ms_DataLogRecv;
	static CHuffman ms_Huffman;
public:
	static void OpenLog(IOHANDLE DataLogSent, IOHANDLE DataLogRecv);
	static void CloseLog();
	static void Init();
	static int Compress(const void *pData, int DataSize, void *pOutput, int OutputSize);
	static int Decompress(const void *pData, int DataSize, void *pOutput, int OutputSize);

	static void SendControlMsg(NETSOCKET Socket, NETADDR *pAddr, int Ack, int ControlMsg, const void *pExtra, int ExtraSize, SECURITY_TOKEN SecurityToken);
	static void SendPacketConnless(NETSOCKET Socket, NETADDR *pAddr, const void *pData, int DataSize, bool Extended, unsigned char aExtra[4]);
	static void SendPacket(NETSOCKET Socket, NETADDR *pAddr, CNetPacketConstruct *pPacket, SECURITY_TOKEN SecurityToken);

	static int UnpackPacket(unsigned char *pBuffer, int Size, CNetPacketConstruct *pPacket);

	// The backroom is ack-NET_MAX_SEQUENCE/2. Used for knowing if we acked a packet or not
	static int IsSeqInBackroom(int Seq, int Ack);
};


#endif
