/* (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.                */
#include <base/system.h>

#include "config.h"
#include "huffman.h"
#include "network.h"

const unsigned char SECURITY_TOKEN_MAGIC[4] = {'T', 'K', 'E', 'N'};

void CNetRecvUnpacker::Clear()
{
	m_Valid = false;
}

void CNetRecvUnpacker::Start(const NETADDR *pAddr, CNetConnection *pConnection, int ClientID)
{
	m_Addr = *pAddr;
	m_pConnection = pConnection;
	m_ClientID = ClientID;
	m_CurrentChunk = 0;
	m_Valid = true;
}

// TODO: rename this function
int CNetRecvUnpacker::FetchChunk(CNetChunk *pChunk)
{
	CNetChunkHeader Header;
	unsigned char *pEnd = m_Data.m_aChunkData + m_Data.m_DataSize;

	while(true)
	{
		unsigned char *pData = m_Data.m_aChunkData;

		// check for old data to unpack
		if(!m_Valid || m_CurrentChunk >= m_Data.m_NumChunks)
		{
			Clear();
			return 0;
		}

		// TODO: add checking here so we don't read too far
		for(int i = 0; i < m_CurrentChunk; i++)
		{
			pData = Header.Unpack(pData, (m_pConnection && m_pConnection->m_Sixup) ? 6 : 4);
			pData += Header.m_Size;
		}

		// unpack the header
		pData = Header.Unpack(pData, (m_pConnection && m_pConnection->m_Sixup) ? 6 : 4);
		m_CurrentChunk++;

		if(pData + Header.m_Size > pEnd)
		{
			Clear();
			return 0;
		}

		// handle sequence stuff
		if(m_pConnection && (Header.m_Flags & NET_CHUNKFLAG_VITAL))
		{
			// anti spoof: ignore unknown sequence
			if(Header.m_Sequence == (m_pConnection->m_Ack + 1) % NET_MAX_SEQUENCE || m_pConnection->m_UnknownSeq)
			{
				m_pConnection->m_UnknownSeq = false;

				// in sequence
				m_pConnection->m_Ack = Header.m_Sequence;
			}
			else
			{
				// old packet that we already got
				if(CNetBase::IsSeqInBackroom(Header.m_Sequence, m_pConnection->m_Ack))
					continue;

				// out of sequence, request resend
				if(g_Config.m_Debug)
					dbg_msg("conn", "asking for resend %d %d", Header.m_Sequence, (m_pConnection->m_Ack + 1) % NET_MAX_SEQUENCE);
				m_pConnection->SignalResend();
				continue; // take the next chunk in the packet
			}
		}

		// fill in the info
		pChunk->m_ClientID = m_ClientID;
		pChunk->m_Address = m_Addr;
		pChunk->m_Flags = Header.m_Flags;
		pChunk->m_DataSize = Header.m_Size;
		pChunk->m_pData = pData;
		return 1;
	}
}

static const unsigned char NET_HEADER_EXTENDED[] = {'x', 'e'};
// packs the data tight and sends it
void CNetBase::SendPacketConnless(NETSOCKET Socket, NETADDR *pAddr, const void *pData, int DataSize, bool Extended, unsigned char aExtra[4])
{
	unsigned char aBuffer[NET_MAX_PACKETSIZE];
	const int DATA_OFFSET = 6;
	if(!Extended)
	{
		for(int i = 0; i < DATA_OFFSET; i++)
			aBuffer[i] = 0xff;
	}
	else
	{
		mem_copy(aBuffer, NET_HEADER_EXTENDED, sizeof(NET_HEADER_EXTENDED));
		mem_copy(aBuffer + sizeof(NET_HEADER_EXTENDED), aExtra, 4);
	}
	mem_copy(aBuffer + DATA_OFFSET, pData, DataSize);
	net_udp_send(Socket, pAddr, aBuffer, DataSize + DATA_OFFSET);
}

void CNetBase::SendPacket(NETSOCKET Socket, NETADDR *pAddr, CNetPacketConstruct *pPacket, SECURITY_TOKEN SecurityToken, bool Sixup, bool NoCompress)
{
	unsigned char aBuffer[NET_MAX_PACKETSIZE];
	int CompressedSize = -1;
	int FinalSize = -1;

	// log the data
	if(ms_DataLogSent)
	{
		int Type = 1;
		io_write(ms_DataLogSent, &Type, sizeof(Type));
		io_write(ms_DataLogSent, &pPacket->m_DataSize, sizeof(pPacket->m_DataSize));
		io_write(ms_DataLogSent, &pPacket->m_aChunkData, pPacket->m_DataSize);
		io_flush(ms_DataLogSent);
	}

	int HeaderSize = NET_PACKETHEADERSIZE;
	if(Sixup)
	{
		HeaderSize += sizeof(SecurityToken);
		mem_copy(&aBuffer[3], &SecurityToken, sizeof(SecurityToken));
	}
	else if(SecurityToken != NET_SECURITY_TOKEN_UNSUPPORTED)
	{
		// append security token
		// if SecurityToken is NET_SECURITY_TOKEN_UNKNOWN we will still append it hoping to negotiate it
		mem_copy(&pPacket->m_aChunkData[pPacket->m_DataSize], &SecurityToken, sizeof(SecurityToken));
		pPacket->m_DataSize += sizeof(SecurityToken);
	}

	// compress
	if(!NoCompress)
		CompressedSize = ms_Huffman.Compress(pPacket->m_aChunkData, pPacket->m_DataSize, &aBuffer[HeaderSize], NET_MAX_PACKETSIZE - HeaderSize);

	// check if the compression was enabled, successful and good enough
	if(!NoCompress && CompressedSize > 0 && CompressedSize < pPacket->m_DataSize)
	{
		FinalSize = CompressedSize;
		pPacket->m_Flags |= NET_PACKETFLAG_COMPRESSION;
	}
	else
	{
		// use uncompressed data
		FinalSize = pPacket->m_DataSize;
		mem_copy(&aBuffer[HeaderSize], pPacket->m_aChunkData, pPacket->m_DataSize);
		pPacket->m_Flags &= ~NET_PACKETFLAG_COMPRESSION;
	}

	if(Sixup)
	{
		unsigned Flags = 0;
		if(pPacket->m_Flags & NET_PACKETFLAG_CONTROL)
			Flags |= 1;
		if(pPacket->m_Flags & NET_PACKETFLAG_RESEND)
			Flags |= 2;
		if(pPacket->m_Flags & NET_PACKETFLAG_COMPRESSION)
			Flags |= 4;
		pPacket->m_Flags = Flags;
	}

	// set header and send the packet if all things are good
	if(FinalSize >= 0)
	{
		FinalSize += HeaderSize;
		aBuffer[0] = ((pPacket->m_Flags << 2) & 0xfc) | ((pPacket->m_Ack >> 8) & 0x3);
		aBuffer[1] = pPacket->m_Ack & 0xff;
		aBuffer[2] = pPacket->m_NumChunks;
		net_udp_send(Socket, pAddr, aBuffer, FinalSize);

		// log raw socket data
		if(ms_DataLogSent)
		{
			int Type = 0;
			io_write(ms_DataLogSent, &Type, sizeof(Type));
			io_write(ms_DataLogSent, &FinalSize, sizeof(FinalSize));
			io_write(ms_DataLogSent, aBuffer, FinalSize);
			io_flush(ms_DataLogSent);
		}
	}
}

// TODO: rename this function
int CNetBase::UnpackPacket(unsigned char *pBuffer, int Size, CNetPacketConstruct *pPacket, bool &Sixup, SECURITY_TOKEN *pSecurityToken, SECURITY_TOKEN *pResponseToken)
{
	// check the size
	if(Size < NET_PACKETHEADERSIZE || Size > NET_MAX_PACKETSIZE)
		return -1;

	// log the data
	if(ms_DataLogRecv)
	{
		int Type = 0;
		io_write(ms_DataLogRecv, &Type, sizeof(Type));
		io_write(ms_DataLogRecv, &Size, sizeof(Size));
		io_write(ms_DataLogRecv, pBuffer, Size);
		io_flush(ms_DataLogRecv);
	}

	// read the packet
	pPacket->m_Flags = pBuffer[0] >> 2;

	if(pPacket->m_Flags & NET_PACKETFLAG_CONNLESS)
	{
		Sixup = (pBuffer[0] & 0x3) == 1;
		if(Sixup && (pSecurityToken == nullptr || pResponseToken == nullptr))
			return -1;
		int Offset = Sixup ? 9 : 6;
		if(Size < Offset)
			return -1;

		if(Sixup)
		{
			mem_copy(pSecurityToken, &pBuffer[1], sizeof(*pSecurityToken));
			mem_copy(pResponseToken, &pBuffer[5], sizeof(*pResponseToken));
		}

		pPacket->m_Flags = NET_PACKETFLAG_CONNLESS;
		pPacket->m_Ack = 0;
		pPacket->m_NumChunks = 0;
		pPacket->m_DataSize = Size - Offset;
		mem_copy(pPacket->m_aChunkData, pBuffer + Offset, pPacket->m_DataSize);

		if(!Sixup && mem_comp(pBuffer, NET_HEADER_EXTENDED, sizeof(NET_HEADER_EXTENDED)) == 0)
		{
			pPacket->m_Flags |= NET_PACKETFLAG_EXTENDED;
			mem_copy(pPacket->m_aExtraData, pBuffer + sizeof(NET_HEADER_EXTENDED), sizeof(pPacket->m_aExtraData));
		}
	}
	else
	{
		if(pPacket->m_Flags & NET_PACKETFLAG_UNUSED)
			Sixup = true;
		if(Sixup && pSecurityToken == nullptr)
			return -1;
		int DataStart = Sixup ? 7 : NET_PACKETHEADERSIZE;
		if(Size < DataStart)
			return -1;

		pPacket->m_Ack = ((pBuffer[0] & 0x3) << 8) | pBuffer[1];
		pPacket->m_NumChunks = pBuffer[2];
		pPacket->m_DataSize = Size - DataStart;

		if(Sixup)
		{
			unsigned Flags = 0;
			if(pPacket->m_Flags & 1)
				Flags |= NET_PACKETFLAG_CONTROL;
			if(pPacket->m_Flags & 2)
				Flags |= NET_PACKETFLAG_RESEND;
			if(pPacket->m_Flags & 4)
				Flags |= NET_PACKETFLAG_COMPRESSION;
			pPacket->m_Flags = Flags;

			mem_copy(pSecurityToken, &pBuffer[3], sizeof(*pSecurityToken));
		}

		if(pPacket->m_Flags & NET_PACKETFLAG_COMPRESSION)
		{
			// Don't allow compressed control packets.
			if(pPacket->m_Flags & NET_PACKETFLAG_CONTROL)
			{
				return -1;
			}
			pPacket->m_DataSize = ms_Huffman.Decompress(&pBuffer[DataStart], pPacket->m_DataSize, pPacket->m_aChunkData, sizeof(pPacket->m_aChunkData));
		}
		else
			mem_copy(pPacket->m_aChunkData, &pBuffer[DataStart], pPacket->m_DataSize);
	}

	// check for errors
	if(pPacket->m_DataSize < 0)
	{
		if(g_Config.m_Debug)
			dbg_msg("network", "error during packet decoding");
		return -1;
	}

	// log the data
	if(ms_DataLogRecv)
	{
		int Type = 1;
		io_write(ms_DataLogRecv, &Type, sizeof(Type));
		io_write(ms_DataLogRecv, &pPacket->m_DataSize, sizeof(pPacket->m_DataSize));
		io_write(ms_DataLogRecv, pPacket->m_aChunkData, pPacket->m_DataSize);
		io_flush(ms_DataLogRecv);
	}

	// return success
	return 0;
}

void CNetBase::SendControlMsg(NETSOCKET Socket, NETADDR *pAddr, int Ack, int ControlMsg, const void *pExtra, int ExtraSize, SECURITY_TOKEN SecurityToken, bool Sixup)
{
	CNetPacketConstruct Construct;
	Construct.m_Flags = NET_PACKETFLAG_CONTROL;
	Construct.m_Ack = Ack;
	Construct.m_NumChunks = 0;
	Construct.m_DataSize = 1 + ExtraSize;
	Construct.m_aChunkData[0] = ControlMsg;
	if(pExtra)
		mem_copy(&Construct.m_aChunkData[1], pExtra, ExtraSize);

	// send the control message
	CNetBase::SendPacket(Socket, pAddr, &Construct, SecurityToken, Sixup, true);
}

unsigned char *CNetChunkHeader::Pack(unsigned char *pData, int Split)
{
	pData[0] = ((m_Flags & 3) << 6) | ((m_Size >> Split) & 0x3f);
	pData[1] = (m_Size & ((1 << Split) - 1));
	if(m_Flags & NET_CHUNKFLAG_VITAL)
	{
		pData[1] |= (m_Sequence >> 2) & (~((1 << Split) - 1));
		pData[2] = m_Sequence & 0xff;
		return pData + 3;
	}
	return pData + 2;
}

unsigned char *CNetChunkHeader::Unpack(unsigned char *pData, int Split)
{
	m_Flags = (pData[0] >> 6) & 3;
	m_Size = ((pData[0] & 0x3f) << Split) | (pData[1] & ((1 << Split) - 1));
	m_Sequence = -1;
	if(m_Flags & NET_CHUNKFLAG_VITAL)
	{
		m_Sequence = ((pData[1] & (~((1 << Split) - 1))) << 2) | pData[2];
		return pData + 3;
	}
	return pData + 2;
}

bool CNetBase::IsSeqInBackroom(int Seq, int Ack)
{
	int Bottom = (Ack - NET_MAX_SEQUENCE / 2);
	if(Bottom < 0)
	{
		if(Seq <= Ack)
			return true;
		if(Seq >= (Bottom + NET_MAX_SEQUENCE))
			return true;
	}
	else
	{
		if(Seq <= Ack && Seq >= Bottom)
			return true;
	}

	return false;
}

IOHANDLE CNetBase::ms_DataLogSent = 0;
IOHANDLE CNetBase::ms_DataLogRecv = 0;
CHuffman CNetBase::ms_Huffman;

void CNetBase::OpenLog(IOHANDLE DataLogSent, IOHANDLE DataLogRecv)
{
	if(DataLogSent)
	{
		ms_DataLogSent = DataLogSent;
		dbg_msg("network", "logging sent packages");
	}
	else
		dbg_msg("network", "failed to start logging sent packages");

	if(DataLogRecv)
	{
		ms_DataLogRecv = DataLogRecv;
		dbg_msg("network", "logging recv packages");
	}
	else
		dbg_msg("network", "failed to start logging recv packages");
}

void CNetBase::CloseLog()
{
	if(ms_DataLogSent)
	{
		dbg_msg("network", "stopped logging sent packages");
		io_close(ms_DataLogSent);
		ms_DataLogSent = 0;
	}

	if(ms_DataLogRecv)
	{
		dbg_msg("network", "stopped logging recv packages");
		io_close(ms_DataLogRecv);
		ms_DataLogRecv = 0;
	}
}

int CNetBase::Compress(const void *pData, int DataSize, void *pOutput, int OutputSize)
{
	return ms_Huffman.Compress(pData, DataSize, pOutput, OutputSize);
}

int CNetBase::Decompress(const void *pData, int DataSize, void *pOutput, int OutputSize)
{
	return ms_Huffman.Decompress(pData, DataSize, pOutput, OutputSize);
}

void CNetBase::Init()
{
	ms_Huffman.Init();
}