// ---------------------------------------------------------------------------80
//                ICQ plugin for Miranda Instant Messenger
//                ________________________________________
// 
// Copyright © 2000-2001 Richard Hughes, Roland Rabien, Tristan Van de Vreede
// Copyright © 2001-2002 Jon Keating, Richard Hughes
// Copyright © 2002-2004 Martin Öberg, Sam Kothari, Robert Rainwater
// Copyright © 2004-2010 Joe Kucera
// Copyright © 2012-2018 Miranda NG team
// 
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
// -----------------------------------------------------------------------------

#include "stdafx.h"

struct directthreadstartinfo
{
	int type;           // Only valid for outgoing connections
	int incoming;       // 1=incoming, 0=outgoing
	HNETLIBCONN hConnection; // only valid for incoming connections, handle to the connection
	MCONTACT hContact;    // Only valid for outgoing connections
	void* pvExtra;      // Only valid for outgoing connections
};

static char client_check_data[] = {
	"As part of this software beta version Mirabilis is "
	"granting a limited access to the ICQ network, "
	"servers, directories, listings, information and databases (\""
	"ICQ Services and Information\"). The "
	"ICQ Service and Information may databases (\""
	"ICQ Services and Information\"). The "
	"ICQ Service and Information may\0"
};

void CIcqProto::CloseContactDirectConns(MCONTACT hContact)
{
	mir_cslock l(directConnListMutex);

	for (auto &it : directConns) {
		if (!hContact || it->hContact == hContact) {
			HNETLIBCONN hConnection = it->hConnection;

			it->hConnection = nullptr; // do not allow reuse
			NetLib_CloseConnection(&hConnection, FALSE);
		}
	}
}


directconnect* CIcqProto::FindFileTransferDC(filetransfer* ft)
{
	mir_cslock l(directConnListMutex);

	for (auto &it : directConns)
		if (it->ft == ft)
			return it;

	return nullptr;
}


filetransfer* CIcqProto::FindExpectedFileRecv(DWORD dwUin, DWORD dwTotalSize)
{
	mir_cslock l(expectedFileRecvMutex);

	for (auto &it : expectedFileRecvs)
		if (it->dwUin == dwUin && it->dwTotalSize == dwTotalSize)
			return expectedFileRecvs.removeItem(&it);

	return nullptr;
}


int CIcqProto::sendDirectPacket(directconnect* dc, icq_packet* pkt)
{
	int nResult = Netlib_Send(dc->hConnection, (const char*)pkt->pData, pkt->wLen + 2, 0);
	if (nResult == SOCKET_ERROR) {
		NetLog_Direct("Direct %p socket error: %d, closing", dc->hConnection, GetLastError());
		CloseDirectConnection(dc);
	}

	SAFE_FREE((void**)&pkt->pData);

	return nResult;
}

directthreadstartinfo* CreateDTSI(MCONTACT hContact, HNETLIBCONN hConnection, int type)
{
	directthreadstartinfo *dtsi = (directthreadstartinfo*)SAFE_MALLOC(sizeof(directthreadstartinfo));
	dtsi->hContact = hContact;
	dtsi->hConnection = hConnection;
	if (type == -1)
		dtsi->incoming = 1;
	else
		dtsi->type = type;

	return dtsi;
}

// Check if we have an open and initialized DC with type
// 'type' to the specified contact
BOOL CIcqProto::IsDirectConnectionOpen(MCONTACT hContact, int type, int bPassive)
{
	BOOL bIsOpen = FALSE, bIsCreated = FALSE;
	{
		mir_cslock l(directConnListMutex);

		for (auto &it : directConns) {
			if (it && it->type == type) {
				if (it->hContact == hContact) {
					if (it->initialised) {
						// Connection is OK
						bIsOpen = TRUE;
						// we are going to use the conn, so prevent timeout
						it->packetPending = 1;
						break;
					}
					else bIsCreated = TRUE; // we found pending connection
				}
			}
		}
	}

	if (!bPassive && !bIsCreated && !bIsOpen && type == DIRECTCONN_STANDARD && m_bDCMsgEnabled == 2) { // do not try to open DC to offline contact
		if (getContactStatus(hContact) == ID_STATUS_OFFLINE) return FALSE;
		// do not try to open DC if previous attempt was not successfull
		if (getByte(hContact, "DCStatus", 0)) return FALSE;

		// Set DC status as tried
		setByte(hContact, "DCStatus", 1);
		// Create a new connection
		OpenDirectConnection(hContact, DIRECTCONN_STANDARD, nullptr);
	}

	return bIsOpen;
}

// This function is called from the Netlib when someone is connecting to
// one of our incomming DC ports
void icq_newConnectionReceived(HNETLIBCONN hNewConnection, DWORD, void *pExtra)
{
	// Start a new thread for the incomming connection
	CIcqProto* ppro = (CIcqProto*)pExtra;
	ppro->ForkThread((CIcqProto::MyThreadFunc)&CIcqProto::icq_directThread, CreateDTSI(NULL, hNewConnection, -1));
}

// Opens direct connection of specified type to specified contact
void CIcqProto::OpenDirectConnection(MCONTACT hContact, int type, void* pvExtra)
{
	// Create a new connection
	directthreadstartinfo* dtsi = CreateDTSI(hContact, nullptr, type);
	dtsi->pvExtra = pvExtra;
	ForkThread((MyThreadFunc)&CIcqProto::icq_directThread, dtsi);
}

// Safely close NetLib connection - do not corrupt direct connection list
void CIcqProto::CloseDirectConnection(directconnect *dc)
{
	mir_cslock l(directConnListMutex);

	NetLib_CloseConnection(&dc->hConnection, FALSE);

	if (dc->hConnection)
		NetLog_Direct("Direct conn closed (%p)", dc->hConnection);
}

// Called from icq_newConnectionReceived when a new incomming dc is done
// Called from OpenDirectConnection when a new outgoing dc is done
// Called from SendDirectMessage when a new outgoing dc is done

void __cdecl CIcqProto::icq_directThread(directthreadstartinfo *dtsi)
{
	Thread_SetName("ICQ: directThread");

	NETLIBPACKETRECVER packetRecv = {};
	directconnect dc = { 0 };
	BOOL bFirstPacket = TRUE;
	size_t nSkipPacketBytes = 0;
	DWORD dwReqMsgID1 = 0, dwReqMsgID2 = 0;

	srand(time(0));
	{
		// add to DC connection list
		mir_cslock l(directConnListMutex);
		directConns.insert(&dc);
	}

	// Initialize DC struct
	dc.hContact = dtsi->hContact;
	dc.dwThreadId = GetCurrentThreadId();
	dc.incoming = dtsi->incoming;
	dc.hConnection = dtsi->hConnection;
	dc.ft = nullptr;

	if (!dc.incoming) {
		dc.type = dtsi->type;
		dc.dwRemoteExternalIP = getDword(dtsi->hContact, "IP", 0);
		dc.dwRemoteInternalIP = getDword(dtsi->hContact, "RealIP", 0);
		dc.dwRemotePort = getWord(dtsi->hContact, "UserPort", 0);
		dc.dwRemoteUin = getContactUin(dtsi->hContact);
		dc.dwConnectionCookie = getDword(dtsi->hContact, "DirectCookie", 0);
		dc.wVersion = getWord(dtsi->hContact, "Version", 0);

		if (!dc.dwRemoteExternalIP && !dc.dwRemoteInternalIP) { // we do not have any ip, do not try to connect
			SAFE_FREE((void**)&dtsi);
			goto LBL_Exit;
		}
		if (!dc.dwRemotePort) { // we do not have port, do not try to connect
			SAFE_FREE((void**)&dtsi);
			goto LBL_Exit;
		}

		if (dc.type == DIRECTCONN_STANDARD) {
			// do nothing - some specific init for msg sessions
		}
		else if (dc.type == DIRECTCONN_FILE) {
			dc.ft = (filetransfer*)dtsi->pvExtra;
			dc.dwRemotePort = dc.ft->dwRemotePort;
		}
		else if (dc.type == DIRECTCONN_REVERSE) {
			cookie_reverse_connect *pCookie = (cookie_reverse_connect*)dtsi->pvExtra;

			dwReqMsgID1 = pCookie->dwMsgID1;
			dwReqMsgID2 = pCookie->dwMsgID2;
			dc.dwReqId = (UINT_PTR)pCookie->ft;
			SAFE_FREE((void**)&pCookie);
		}
	}
	else dc.type = DIRECTCONN_STANDARD;

	SAFE_FREE((void**)&dtsi);

	// Load local IP information
	dc.dwLocalExternalIP = getDword("IP", 0);
	dc.dwLocalInternalIP = getDword("RealIP", 0);

	// Create outgoing DC
	if (!dc.incoming) {
		NETLIBOPENCONNECTION nloc = { 0 };
		IN_ADDR addr = { 0 }, addr2 = { 0 };

		if (dc.dwRemoteExternalIP == dc.dwLocalExternalIP && dc.dwRemoteInternalIP)
			addr.S_un.S_addr = htonl(dc.dwRemoteInternalIP);
		else {
			addr.S_un.S_addr = htonl(dc.dwRemoteExternalIP);
			// for different internal, try it also (for LANs with multiple external IP, VPNs, etc.)
			if (dc.dwRemoteInternalIP != dc.dwRemoteExternalIP)
				addr2.S_un.S_addr = htonl(dc.dwRemoteInternalIP);
		}

		// IP to connect to is empty, go away
		if (!addr.S_un.S_addr)
			goto LBL_Exit;

		nloc.szHost = inet_ntoa(addr);
		nloc.wPort = (WORD)dc.dwRemotePort;
		nloc.timeout = 8; // 8 secs to connect
		dc.hConnection = NetLib_OpenConnection(m_hDirectNetlibUser, dc.type == DIRECTCONN_REVERSE ? "Reverse " : nullptr, &nloc);
		if (!dc.hConnection && addr2.S_un.S_addr) { // first address failed, try second one if available
			nloc.szHost = inet_ntoa(addr2);
			dc.hConnection = NetLib_OpenConnection(m_hDirectNetlibUser, dc.type == DIRECTCONN_REVERSE ? "Reverse " : nullptr, &nloc);
		}
		if (!dc.hConnection) {
			if (CheckContactCapabilities(dc.hContact, CAPF_ICQDIRECT)) { // only if the contact support ICQ DC connections
				if (dc.type != DIRECTCONN_REVERSE) { // try reverse connect
					cookie_reverse_connect *pCookie = (cookie_reverse_connect*)SAFE_MALLOC(sizeof(cookie_reverse_connect));
					DWORD dwCookie;

					NetLog_Direct("connect() failed (%d), trying reverse.", GetLastError());

					if (pCookie) { // init cookie
						InitMessageCookie(pCookie);
						pCookie->bMessageType = MTYPE_REVERSE_REQUEST;
						pCookie->hContact = dc.hContact;
						pCookie->dwUin = dc.dwRemoteUin;
						pCookie->type = dc.type;
						pCookie->ft = dc.ft;
						dwCookie = AllocateCookie(CKT_REVERSEDIRECT, 0, dc.hContact, pCookie);
						icq_sendReverseReq(&dc, dwCookie, (cookie_message_data*)pCookie);
						goto LBL_Exit;
					}

					NetLog_Direct("Reverse failed (%s)", "malloc failed");
				}
			}
			else // Set DC status to failed
				setByte(dc.hContact, "DCStatus", 2);

			if (dc.type == DIRECTCONN_REVERSE) // failed reverse connection
				icq_sendReverseFailed(&dc, dwReqMsgID1, dwReqMsgID2, dc.dwReqId);

			NetLog_Direct("connect() failed (%d)", GetLastError());
			if (dc.type == DIRECTCONN_FILE) {
				ProtoBroadcastAck(dc.ft->hContact, ACKTYPE_FILE, ACKRESULT_FAILED, dc.ft, 0);
				// Release transfer
				SafeReleaseFileTransfer((basic_filetransfer**)&dc.ft);
			}
			goto LBL_Exit;
		}

		if (dc.type == DIRECTCONN_FILE)
			dc.ft->hConnection = dc.hConnection;

		if (dc.wVersion > 6)
			sendPeerInit_v78(&dc);
		else {
			NetLog_Direct("Error: Unsupported direct protocol: %d, closing.", dc.wVersion);
			CloseDirectConnection(&dc);
			goto LBL_Exit;
		}
	}

	HANDLE hPacketRecver = Netlib_CreatePacketReceiver(dc.hConnection, 8192);

	// Packet receiving loop

	while (dc.hConnection) {
		packetRecv.dwTimeout = dc.wantIdleTime ? 0 : 600000;

		int recvResult = Netlib_GetMorePackets(hPacketRecver, &packetRecv);
		if (recvResult == 0) {
			NetLog_Direct("Clean closure of direct socket (%p)", dc.hConnection);
			break;
		}

		if (recvResult == SOCKET_ERROR) {
			if (GetLastError() == ERROR_TIMEOUT) { // TODO: this will not work on some systems
				if (dc.wantIdleTime) {
					switch (dc.type) {
					case DIRECTCONN_FILE:
						handleFileTransferIdle(&dc);
						break;
					}
				}
				else if (dc.packetPending) { // do we expect packet soon?
					NetLog_Direct("Keeping connection, packet pending.");
				}
				else {
					NetLog_Direct("Connection inactive for 10 minutes, closing.");
					break;
				}
			}
			else {
				NetLog_Direct("Abortive closure of direct socket (%p) (%d)", dc.hConnection, GetLastError());
				break;
			}
		}

		if (dc.type == DIRECTCONN_CLOSING)
			packetRecv.bytesUsed = packetRecv.bytesAvailable;
		else if (packetRecv.bytesAvailable < (int)nSkipPacketBytes) { // the whole buffer needs to be skipped
			nSkipPacketBytes -= packetRecv.bytesAvailable;
			packetRecv.bytesUsed = packetRecv.bytesAvailable;
		}
		else {
			size_t i;
			for (i = nSkipPacketBytes, nSkipPacketBytes = 0; (int)i + 2 <= packetRecv.bytesAvailable;) {
				size_t wLen = *(WORD*)(packetRecv.buffer + i);

				if (bFirstPacket) {
					if (wLen > 64) { // roughly check first packet size
						NetLog_Direct("Error: Overflowed packet, closing connection.");
						CloseDirectConnection(&dc);
						break;
					}
					bFirstPacket = FALSE;
				}
				else if (packetRecv.bytesAvailable >= (int)i + 2 && wLen > 8190) { // check for too big packages
					NetLog_Direct("Error: Package too big: %d bytes, skipping.");
					nSkipPacketBytes = wLen;
					packetRecv.bytesUsed = int(i + 2);
					break;
				}

				if (wLen + 2 + i > (size_t)packetRecv.bytesAvailable)
					break;

				if (dc.type == DIRECTCONN_STANDARD && wLen && packetRecv.buffer[i + 2] == 2) {
					if (!DecryptDirectPacket(&dc, packetRecv.buffer + i + 3, wLen - 1)) {
						NetLog_Direct("Error: Corrupted packet encryption, ignoring packet");
						i += wLen + 2;
						continue;
					}
				}

				if (dc.type == DIRECTCONN_FILE && dc.initialised)
					handleFileTransferPacket(&dc, packetRecv.buffer + i + 2, wLen);
				else
					handleDirectPacket(&dc, packetRecv.buffer + i + 2, wLen);

				i += wLen + 2;
			}
			packetRecv.bytesUsed = (int)i;
		}
	}

	// End of packet receiving loop
	NetLib_SafeCloseHandle(&hPacketRecver);
	CloseDirectConnection(&dc);

	if (dc.ft) {
		if (dc.ft->fileId != -1) {
			_close(dc.ft->fileId);
			ProtoBroadcastAck(dc.ft->hContact, ACKTYPE_FILE, dc.ft->dwBytesDone == dc.ft->dwTotalSize ? ACKRESULT_SUCCESS : ACKRESULT_FAILED, dc.ft, 0);
		}
		else if (dc.ft->hConnection)
			ProtoBroadcastAck(dc.ft->hContact, ACKTYPE_FILE, ACKRESULT_FAILED, dc.ft, 0);

		SafeReleaseFileTransfer((basic_filetransfer**)&dc.ft);
		_chdir("\\");    /* so we don't leave a subdir handle open so it can't be deleted */
	}

LBL_Exit:
	// remove from DC connection list
	mir_cslock l(directConnListMutex);
	directConns.remove(&dc);
}

void CIcqProto::handleDirectPacket(directconnect* dc, PBYTE buf, size_t wLen)
{
	if (wLen < 1)
		return;

	switch (buf[0]) {
	case PEER_FILE_INIT: // first packet of a file transfer
		NetLog_Direct("Received PEER_FILE_INIT from %u", dc->dwRemoteUin);

		if (dc->handshake)
			handleFileTransferPacket(dc, buf, wLen);
		else
			NetLog_Direct("Received %s on uninitialised DC, ignoring.", "PEER_FILE_INIT");

		break;

	case PEER_INIT_ACK: // This is sent as a response to our PEER_INIT packet
		if (wLen != 4) {
			NetLog_Direct("Error: Received malformed PEER_INITACK from %u", dc->dwRemoteUin);
			break;
		}

		NetLog_Direct("Received PEER_INITACK from %u on %s DC", dc->dwRemoteUin, dc->incoming ? "incoming" : "outgoing");

		if (dc->incoming) dc->handshake = 1;

		if (dc->incoming && dc->type == DIRECTCONN_REVERSE) {
			dc->incoming = 0;

			cookie_reverse_connect *pCookie;
			if (FindCookie(dc->dwReqId, nullptr, (void**)&pCookie) && pCookie) { // valid reverse DC, check and init session
				FreeCookie(dc->dwReqId);
				if (pCookie->dwUin == dc->dwRemoteUin) { // valid connection
					dc->type = pCookie->type;
					dc->ft = (filetransfer*)pCookie->ft;
					dc->hContact = pCookie->hContact;
					if (dc->type == DIRECTCONN_STANDARD) { // init message session
						sendPeerMsgInit(dc, 0);
					}
					else if (dc->type == DIRECTCONN_FILE) { // init file session
						sendPeerFileInit(dc);
						dc->initialised = 1;
					}
					SAFE_FREE((void**)&pCookie);
					break;
				}
				else {
					SAFE_FREE((void**)&pCookie);
					NetLog_Direct("Error: Invalid connection (UINs does not match).");
					CloseDirectConnection(dc);
					return;
				}
			}
			else {
				NetLog_Direct("Error: Received unexpected reverse DC, closing.");
				CloseDirectConnection(dc);
				return;
			}
		}
		break;

	case PEER_INIT:       /* connect packet */
		NetLog_Direct("Received PEER_INIT");

		buf++;

		if (wLen < 3)
			return;

		unpackLEWord(&buf, &dc->wVersion);

		if (dc->wVersion > 6) { // we support only versions 7 and up
			DWORD dwUin;
			DWORD dwPort;
			DWORD dwCookie;
			MCONTACT hContact = 0;

			if (wLen != 0x30) {
				NetLog_Direct("Error: Received malformed PEER_INIT");
				return;
			}

			size_t wSecondLen;
			unpackLEWord(&buf, &wSecondLen);
			if (wSecondLen && wSecondLen != 0x2b) { // OMG? GnomeICU sets this to zero
				NetLog_Direct("Error: Received malformed PEER_INIT");
				return;
			}

			unpackLEDWord(&buf, &dwUin);
			if (dwUin != m_dwLocalUIN) {
				NetLog_Direct("Error: Received PEER_INIT targeted to %u", dwUin);
				CloseDirectConnection(dc);
				return;
			}

			buf += 2;   /* 00 00 */
			unpackLEDWord(&buf, &dc->dwRemotePort);
			unpackLEDWord(&buf, &dc->dwRemoteUin);
			unpackDWord(&buf, &dc->dwRemoteExternalIP);
			unpackDWord(&buf, &dc->dwRemoteInternalIP);
			buf++;     /* 04: accept direct connections */
			unpackLEDWord(&buf, &dwPort);
			if (dwPort != dc->dwRemotePort) {
				NetLog_Direct("Error: Received malformed PEER_INIT (invalid port)");
				return;
			}
			unpackLEDWord(&buf, &dwCookie);

			buf += 8; // Unknown stuff
			unpackLEDWord(&buf, &dc->dwReqId);

			if (dc->dwRemoteUin || !dc->dwReqId) { // OMG! Licq sends on reverse connection empty uin
				hContact = HContactFromUIN(dc->dwRemoteUin, nullptr);
				if (hContact == INVALID_CONTACT_ID) {
					NetLog_Direct("Error: Received PEER_INIT from %u not on my list", dwUin);
					CloseDirectConnection(dc);
					return;   /* don't allow direct connection with people not on my clist */
				}

				if (dc->incoming) { // this is the first PEER_INIT with our cookie
					if (dwCookie != getDword(hContact, "DirectCookie", 0)) {
						NetLog_Direct("Error: Received PEER_INIT with broken cookie");
						CloseDirectConnection(dc);
						return;
					}
				}
				else { // this is the second PEER_INIT with peer cookie
					if (dwCookie != dc->dwConnectionCookie) {
						NetLog_Direct("Error: Received PEER_INIT with broken cookie");
						CloseDirectConnection(dc);
						return;
					}
				}
			}

			if (dc->incoming && dc->dwReqId) { // this is reverse connection
				dc->type = DIRECTCONN_REVERSE;
				if (!dc->dwRemoteUin) { // we need to load cookie (licq)
					cookie_reverse_connect *pCookie;

					if (FindCookie(dc->dwReqId, nullptr, (void**)&pCookie) && pCookie) { // valid reverse DC, check and init session
						dc->dwRemoteUin = pCookie->dwUin;
						dc->hContact = pCookie->hContact;
					}
					else {
						NetLog_Direct("Error: Received unexpected reverse DC, closing.");
						CloseDirectConnection(dc);
						return;
					}
				}
			}

			sendPeerInitAck(dc); // ack good PEER_INIT packet

			if (dc->incoming) { // store good IP info
				dc->hContact = hContact;
				dc->dwConnectionCookie = dwCookie;
				setDword(dc->hContact, "IP", dc->dwRemoteExternalIP);
				setDword(dc->hContact, "RealIP", dc->dwRemoteInternalIP);
				sendPeerInit_v78(dc); // reply with our PEER_INIT
			}
			else { // outgoing
				dc->handshake = 1;

				if (dc->type == DIRECTCONN_REVERSE) {
					dc->incoming = 1; // this is incoming reverse connection
					dc->type = DIRECTCONN_STANDARD; // we still do not know type
				}
				else if (dc->type == DIRECTCONN_STANDARD) { // send PEER_MSGINIT
					sendPeerMsgInit(dc, 0);
				}
				else if (dc->type == DIRECTCONN_FILE) {
					sendPeerFileInit(dc);
					dc->initialised = 1;
				}
			}
			// Set DC Status to successful
			setByte(dc->hContact, "DCStatus", 0);
		}
		else {
			NetLog_Direct("Unsupported direct protocol: %d, closing connection", dc->wVersion);
			CloseDirectConnection(dc);
		}
		break;

	case PEER_MSG:        /* messaging packets */
		NetLog_Direct("Received PEER_MSG from %u", dc->dwRemoteUin);

		if (dc->initialised)
			handleDirectMessage(dc, buf+1, wLen-1);
		else
			NetLog_Direct("Received %s on uninitialised DC, ignoring.", "PEER_MSG");

		break;

	case PEER_MSG_INIT:   /* init message connection */
		// it is sent by both contains GUID of message channel
		if (!m_bDCMsgEnabled) { // DC messaging disabled, close connection
			NetLog_Direct("Messaging DC requested, denied");
			CloseDirectConnection(dc);
			break;
		}

		NetLog_Direct("Received PEER_MSG_INIT from %u", dc->dwRemoteUin);

		buf++;
		if (wLen != 0x21)
			break;

		if (!dc->handshake) {
			NetLog_Direct("Received %s on unitialised DC, ignoring.", "PEER_MSG_INIT");
			break;
		}
		{
			DWORD q1, q2, q3, q4;

			buf += 4;   /* always 10 */
			buf += 4;   /* some id */
			buf += 4;   /* sequence - always 0 on incoming */
			unpackDWord(&buf, &q1);   // session type GUID
			unpackDWord(&buf, &q2);
			if (!dc->incoming) // skip marker on sequence 1
				buf += 4;

			unpackDWord(&buf, &q3);
			unpackDWord(&buf, &q4);
			if (!CompareGUIDs(q1, q2, q3, q4, PSIG_MESSAGE)) { // This is not for normal messages, useless so kill.
				if (CompareGUIDs(q1, q2, q3, q4, PSIG_STATUS_PLUGIN))
					NetLog_Direct("Status Manager Plugin connections not supported, closing.");
				else if (CompareGUIDs(q1, q2, q3, q4, PSIG_INFO_PLUGIN))
					NetLog_Direct("Info Manager Plugin connection not supported, closing.");
				else
					NetLog_Direct("Unknown connection type init, closing.");

				CloseDirectConnection(dc);
				break;
			}
		}

		if (dc->incoming)  // reply with our PEER_MSG_INIT
			sendPeerMsgInit(dc, 1);

		NetLog_Direct("Direct message session ready.");
		dc->initialised = 1;
		break;

	default:
		NetLog_Direct("Unknown direct packet ignored.");
		break;
	}
}

void EncryptDirectPacket(directconnect* dc, icq_packet* p)
{
	unsigned long B1;
	unsigned long M1;
	unsigned long check;
	unsigned int i;
	unsigned char X1;
	unsigned char X2;
	unsigned char X3;
	unsigned char* buf = (unsigned char*)(p->pData + 3);
	unsigned char bak[6];
	unsigned long offset;
	unsigned long key;
	unsigned long hex;
	unsigned long size = p->wLen - 1;

	if (dc->wVersion < 4)
		return;  // no encryption necessary.

	switch (dc->wVersion) {
	case 4:
	case 5:
		offset = 6;
		break;

	default:
		offset = 0;
	}

	// calculate verification data
	M1 = (rand() % ((size < 255 ? size : 255) - 10)) + 10;
	X1 = buf[M1] ^ 0xFF;
	X2 = rand() % 220;
	X3 = client_check_data[X2] ^ 0xFF;
	if (offset) {
		memcpy(bak, buf, sizeof(bak));
		B1 = (buf[offset + 4] << 24) | (buf[offset + 6] << 16) | (buf[2] << 8) | buf[0];
	}
	else B1 = (buf[4] << 24) | (buf[6] << 16) | (buf[4] << 8) | (buf[6]);

	// calculate checkcode
	check = (M1 << 24) | (X1 << 16) | (X2 << 8) | X3;
	check ^= B1;

	// main XOR key
	key = 0x67657268 * size + check;

	// XORing the actual data
	for (i = 0; i < (size + 3) / 4; i += 4) {
		hex = key + client_check_data[i & 0xFF];
		*(PDWORD)(buf + i) ^= hex;
	}

	// in TCPv4 are the first 6 bytes unencrypted
	// so restore them
	if (offset)
		memcpy(buf, bak, sizeof(bak));

	// storing the checkcode
	*(PDWORD)(buf + offset) = check;
}

int DecryptDirectPacket(directconnect* dc, PBYTE buf, size_t wLen)
{
	unsigned long hex;
	unsigned long B1;
	unsigned long M1;
	unsigned int i;
	unsigned char X1;
	unsigned char X2;
	unsigned char X3;
	unsigned char bak[6];
	unsigned long size = (unsigned long)wLen;

	if (dc->wVersion < 4)
		return 1;  // no decryption necessary.

	if (size < 4)
		return 1;

	// backup the first 6 bytes
	unsigned long offset = (dc->wVersion == 4 || dc->wVersion == 5) ? 6 : 0;
	if (offset)
		memcpy(bak, buf, sizeof(bak));

	// retrieve checkcode
	unsigned long check = *(PDWORD)(buf + offset);

	// main XOR key
	unsigned long key = 0x67657268 * size + check;

	for (i = 4; i < (size + 3) / 4; i += 4) {
		hex = key + client_check_data[i & 0xFF];
		*(PDWORD)(buf + i) ^= hex;
	}

	// retrive validate data
	if (offset) {
		// in TCPv4 are the first 6 bytes unencrypted
		// so restore them
		memcpy(buf, bak, sizeof(bak));
		B1 = (buf[offset + 4] << 24) | (buf[offset + 6] << 16) | (buf[2] << 8) | buf[0];
	}
	else B1 = (buf[4] << 24) | (buf[6] << 16) | (buf[4] << 8) | (buf[6] << 0);

	// special decryption
	B1 ^= check;

	// validate packet
	M1 = (B1 >> 24) & 0xFF;
	if (M1 < 10 || M1 >= size)
		return 0;

	X1 = buf[M1] ^ 0xFF;
	if (((B1 >> 16) & 0xFF) != X1)
		return 0;

	X2 = (BYTE)((B1 >> 8) & 0xFF);
	if (X2 < 220) {
		X3 = client_check_data[X2] ^ 0xFF;
		if ((B1 & 0xFF) != X3)
			return 0;
	}

	return 1;
}

// This should be called only if connection already exists
int CIcqProto::SendDirectMessage(MCONTACT hContact, icq_packet *pkt)
{
	mir_cslock l(directConnListMutex);

	for (auto &it : directConns) {
		if (it == nullptr)
			continue;

		if (it->hContact == hContact) {
			if (it->initialised) {
				// This connection can be reused, send packet and exit
				NetLog_Direct("Sending direct message");

				if (pkt->pData[2] == 2)
					EncryptDirectPacket(it, pkt);

				sendDirectPacket(it, pkt);
				it->packetPending = 0; // packet done

				return TRUE; // Success
			}
			break; // connection not ready, use server instead
		}
	}

	return FALSE; // connection pending, we failed, use server instead
}

// Sends a PEER_INIT packet through a DC
// -----------------------------------------------------------------------
// This packet is sent during direct connection initialization between two
// ICQ clients. It is sent by the originator of the connection to start
// the handshake and by the receiver directly after it has sent the
// PEER_ACK packet as a reply to the originator's PEER_INIT. The values
// after the COOKIE field have been added for v7.

void CIcqProto::sendPeerInit_v78(directconnect* dc)
{
	icq_packet packet;
	directPacketInit(&packet, 48);

	packByte(&packet, PEER_INIT);              // Command
	packLEWord(&packet, dc->wVersion);         // Version
	packLEWord(&packet, 43);                   // Data length
	packLEDWord(&packet, dc->dwRemoteUin);     // UIN of remote user
	packWord(&packet, 0);                      // Unknown
	packLEDWord(&packet, wListenPort);         // Our port
	packLEDWord(&packet, m_dwLocalUIN);          // Our UIN
	packDWord(&packet, dc->dwLocalExternalIP); // Our external IP
	packDWord(&packet, dc->dwLocalInternalIP); // Our internal IP
	packByte(&packet, DC_TYPE);                // TCP connection flags
	packLEDWord(&packet, wListenPort);         // Our port
	packLEDWord(&packet, dc->dwConnectionCookie); // DC cookie
	packLEDWord(&packet, WEBFRONTPORT);        // Unknown
	packLEDWord(&packet, CLIENTFEATURES);      // Unknown
	if (dc->type == DIRECTCONN_REVERSE)
		packLEDWord(&packet, dc->dwReqId);       // Reverse Request Cookie
	else
		packDWord(&packet, 0);                   // Unknown

	sendDirectPacket(dc, &packet);

	NetLog_Direct("Sent PEER_INIT to %u on %s DC", dc->dwRemoteUin, dc->incoming ? "incoming" : "outgoing");
}

// Sends a PEER_INIT packet through a DC
// -----------------------------------------------------------------------
// This is sent to acknowledge a PEER_INIT packet.

void CIcqProto::sendPeerInitAck(directconnect* dc)
{
	icq_packet packet;
	directPacketInit(&packet, 4);              // Packet length
	packLEDWord(&packet, PEER_INIT_ACK);       // 

	sendDirectPacket(dc, &packet);

	NetLog_Direct("Sent PEER_INIT_ACK to %u on %s DC", dc->dwRemoteUin, dc->incoming ? "incoming" : "outgoing");
}

// Sends a PEER_MSG_INIT packet through a DC
// -----------------------------------------------------------------------
// This packet starts message session.

void CIcqProto::sendPeerMsgInit(directconnect* dc, DWORD dwSeq)
{
	icq_packet packet;
	directPacketInit(&packet, 33);

	packByte(&packet, PEER_MSG_INIT);
	packLEDWord(&packet, 10);           // unknown
	packLEDWord(&packet, 1);            // message connection
	packLEDWord(&packet, dwSeq);        // sequence is 0,1
	if (!dwSeq) {
		packGUID(&packet, PSIG_MESSAGE);  // message type GUID
		packLEWord(&packet, 1);           // delimiter
		packLEWord(&packet, 4);
	}
	else {
		packDWord(&packet, 0);            // first part of Message GUID
		packDWord(&packet, 0);
		packLEWord(&packet, 1);           // delimiter
		packLEWord(&packet, 4);
		packDWord(&packet, 0);            // second part of Message GUID
		packDWord(&packet, 0);
	}
	sendDirectPacket(dc, &packet);

	NetLog_Direct("Sent PEER_MSG_INIT to %u on %s DC", dc->dwRemoteUin, dc->incoming ? "incoming" : "outgoing");
}

// Sends a PEER_FILE_INIT packet through a DC
// -----------------------------------------------------------------------
// This packet configures file-transfer session.

void CIcqProto::sendPeerFileInit(directconnect* dc)
{
	ptrA tmp(getStringA("Nick"));
	char *szNick = NEWSTR_ALLOCA((tmp == NULL) ? "" : tmp);
	size_t nNickLen = mir_strlen(szNick);

	icq_packet packet;
	directPacketInit(&packet, 20 + nNickLen);

	packByte(&packet, PEER_FILE_INIT);  /* packet type */
	packLEDWord(&packet, 0);            /* unknown */
	packLEDWord(&packet, dc->ft->dwFileCount);
	packLEDWord(&packet, dc->ft->dwTotalSize);
	packLEDWord(&packet, dc->ft->dwTransferSpeed);
	packLEWord(&packet, WORD(nNickLen + 1));
	packBuffer(&packet, (LPBYTE)szNick, nNickLen + 1);
	sendDirectPacket(dc, &packet);

	NetLog_Direct("Sent PEER_FILE_INIT to %u on %s DC", dc->dwRemoteUin, dc->incoming ? "incoming" : "outgoing");
}