//this file is part of eMule
//Copyright (C)2002-2008 Merkur ( strEmail.Format("%s@%s", "devteam", "emule-project.net") / http://www.emule-project.net )
//
//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., 675 Mass Ave, Cambridge, MA 02139, USA.

#include "stdafx.h"
#include "UDPFirewallTester.h"
#include "./Kademlia.h"
#include "./prefs.h"
#include "./SearchManager.h"
#include "../../Log.h"
#include "../../emule.h"
#include "../../emuledlg.h"
#include "../../opcodes.h"
#include "../../clientlist.h"
#include "../routing/RoutingZone.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

using namespace Kademlia;

#define UDP_FIREWALLTEST_CLIENTSTOASK	2	// more clients increase the chance of a false positiv, while less the chance of a false negative 

bool CUDPFirewallTester::m_bFirewalledUDP = false;
bool CUDPFirewallTester::m_bFirewalledLastStateUDP = false;
bool CUDPFirewallTester::m_bIsFWVerifiedUDP = false;
bool CUDPFirewallTester::m_bNodeSearchStarted = false;
bool CUDPFirewallTester::m_bTimedOut = false;
uint8 CUDPFirewallTester::m_byFWChecksRunningUDP = 0;
uint8 CUDPFirewallTester::m_byFWChecksFinishedUDP = 0;
uint32 CUDPFirewallTester::m_dwTestStart = 0;
uint32 CUDPFirewallTester::m_dwLastSucceededTime = 0;
CList<CContact> CUDPFirewallTester::m_liPossibleTestClients;
CList<UsedClient_Struct, UsedClient_Struct&> CUDPFirewallTester::m_liUsedTestClients;

bool CUDPFirewallTester::IsFirewalledUDP(bool bLastStateIfTesting)
{ 
	if (!m_bTimedOut && IsFWCheckUDPRunning())
	{
		if (!m_bFirewalledUDP && CKademlia::IsFirewalled() && m_dwTestStart != 0 && ::GetTickCount() - m_dwTestStart > MIN2MS(6)
			&& !m_bIsFWVerifiedUDP /*For now we don't allow to get firewalled by timeouts if we have succeded a test before, might be changed later*/)
		{
			DebugLogWarning(_T("Firewall UDP Tester: Timeout: Setting UDP status to firewalled after beeing unable to get results for 6 minutes"));
			m_bTimedOut = true;
			theApp.emuledlg->ShowConnectionState();
		}
	}
	else if (m_bTimedOut && IsFWCheckUDPRunning()){
		return true; // firewallstate by timeout
	}
	else if (m_bTimedOut)
		ASSERT( false );

	if (bLastStateIfTesting && IsFWCheckUDPRunning())
		return m_bFirewalledLastStateUDP;
	else
		return m_bFirewalledUDP;
}
bool CUDPFirewallTester::GetUDPCheckClientsNeeded()
{ // are we in search for testclients
	return (m_byFWChecksRunningUDP + m_byFWChecksFinishedUDP) < UDP_FIREWALLTEST_CLIENTSTOASK;
}

void CUDPFirewallTester::SetUDPFWCheckResult(bool bSucceeded, bool bTestCancelled, uint32 uFromIP, uint16 nIncomingPort){
	// check if we actually requested a firewallcheck from this cleint
	bool bRequested = false;
	for (POSITION pos = m_liUsedTestClients.GetHeadPosition(); pos != NULL; m_liUsedTestClients.GetNext(pos)){
		if (m_liUsedTestClients.GetAt(pos).contact.GetIPAddress() == uFromIP){
			
			if (!IsFWCheckUDPRunning() && !m_bFirewalledUDP && m_bIsFWVerifiedUDP && m_dwLastSucceededTime + SEC2MS(10) > ::GetTickCount()
				&& nIncomingPort == CKademlia::GetPrefs()->GetInternKadPort() && CKademlia::GetPrefs()->GetUseExternKadPort())
			{
				// our test finished already in the last 10 seconds with being open because we received a proper result packet before
				// however we now receive another answer packet on our incoming port (which is not unusal as both resultpackets are sent
				// nearly at the same time and UDP doesn't cares if the order stays), while the one before was received on our extern port
				// Because a proper forwarded intern port is more reliable to stay open, than a extern port set by the NAT, we prefer
				// intern ports and change the setting.
				CKademlia::GetPrefs()->SetUseExternKadPort(false);
				DebugLog(_T("Corrected UDP firewall result: Using open internal (%u) instead open external port"), nIncomingPort);
				theApp.emuledlg->ShowConnectionState();
				return;
			}
			else if (m_liUsedTestClients.GetAt(pos).bAnswered){
				// we already received an answer. This may happen since all tests contain of two answer pakcets
				// , but the answer could also be too late and we already counted it as failure.
				return;
			}
			else
				m_liUsedTestClients.GetAt(pos).bAnswered = true;
			bRequested = true;
			break;
		}
	}
	if (!bRequested){
		DebugLogWarning(_T("Unrequested UDPFWCheckResult from %s"), ipstr(ntohl(uFromIP)));
		return;
	}

	if (!IsFWCheckUDPRunning()) // its all over already
		return;

	if (m_byFWChecksRunningUDP == 0)
		ASSERT( false );
	else
		m_byFWChecksRunningUDP--;

	if (!bTestCancelled){
		m_byFWChecksFinishedUDP++;
		if (bSucceeded){	//one positive result is enough
			m_dwTestStart = 0;
			m_bFirewalledUDP = false;
			m_bIsFWVerifiedUDP = true;
			m_bTimedOut = false;
			m_byFWChecksFinishedUDP = UDP_FIREWALLTEST_CLIENTSTOASK; // dont do any more tests			
			m_byFWChecksRunningUDP = 0; // all other tests are cancelled
			m_liPossibleTestClients.RemoveAll(); // clear list, keep used clients list through
			m_dwLastSucceededTime = ::GetTickCount(); // for delayed results, see above
			CSearchManager::CancelNodeFWCheckUDPSearch(); // cancel firewallnode searches if any are still active
			// if this packet came to our internal port, explict set the interal port as used port from now on
			if (nIncomingPort == CKademlia::GetPrefs()->GetInternKadPort()){
				CKademlia::GetPrefs()->SetUseExternKadPort(false);
				DebugLog(_T("New KAD Firewallstate (UDP): Open, using intern port"));
			}
			else if (nIncomingPort == CKademlia::GetPrefs()->GetExternalKadPort()){
				CKademlia::GetPrefs()->SetUseExternKadPort(true);
				DebugLog(_T("New KAD Firewallstate (UDP): Open, using extern port"));
			}
			theApp.emuledlg->ShowConnectionState();
			
			return;
		}
		else if (m_byFWChecksFinishedUDP >= UDP_FIREWALLTEST_CLIENTSTOASK) {
			// seems we are firewalled
			m_dwTestStart = 0;
			DebugLog(_T("New KAD Firewallstate (UDP): Firewalled"));
			m_bFirewalledUDP = true;
			m_bIsFWVerifiedUDP = true;
			m_bTimedOut = false;
			theApp.emuledlg->ShowConnectionState();
			m_liPossibleTestClients.RemoveAll(); // clear list, keep used clients list through
			CSearchManager::CancelNodeFWCheckUDPSearch(); // cancel firewallnode searches if any are still active
			return;
		}
		else
			DebugLogWarning(_T("Kad UDP firewalltest from %s result: Firewalled, continue testing"), ipstr(ntohl(uFromIP)));
	}
	else
		DebugLogWarning(_T("Kad UDP firewalltest from %s cancelled"), ipstr(ntohl(uFromIP)));
	QueryNextClient();
}
void CUDPFirewallTester::ReCheckFirewallUDP(bool bSetUnverified){
	ASSERT( m_byFWChecksRunningUDP == 0 );
	m_byFWChecksRunningUDP = 0;
	m_byFWChecksFinishedUDP = 0;
	m_dwLastSucceededTime = 0;
	m_dwTestStart = ::GetTickCount();
	m_bTimedOut = false;
	m_bFirewalledLastStateUDP = m_bFirewalledUDP;
	m_bIsFWVerifiedUDP = (m_bIsFWVerifiedUDP && !bSetUnverified);
	CSearchManager::FindNodeFWCheckUDP(); // start a lookup for a random node to find suitable IPs
	m_bNodeSearchStarted = true;
	CKademlia::GetPrefs()->SetExternKadPort(0);
}

void CUDPFirewallTester::Connected(){
	if (!m_bNodeSearchStarted && IsFWCheckUDPRunning()){
		CSearchManager::FindNodeFWCheckUDP(); // start a lookup for a random node to find suitable IPs
		m_bNodeSearchStarted = true;
		m_dwTestStart = ::GetTickCount();
		m_bTimedOut = false;
	}
}

bool CUDPFirewallTester::IsFWCheckUDPRunning()
{
	return m_byFWChecksFinishedUDP < UDP_FIREWALLTEST_CLIENTSTOASK;
}

void CUDPFirewallTester::Reset(){
	m_bFirewalledUDP = false;
	m_bFirewalledLastStateUDP = false;
	m_bIsFWVerifiedUDP = false;
	m_bNodeSearchStarted = false;
	m_bTimedOut = false;
	m_byFWChecksRunningUDP = 0;
	m_byFWChecksFinishedUDP = 0;
	m_dwTestStart = 0;
	m_dwLastSucceededTime = 0;
	CSearchManager::CancelNodeFWCheckUDPSearch(); // cancel firewallnode searches if any are stilla ctive
	m_liPossibleTestClients.RemoveAll();
	CKademlia::GetPrefs()->SetUseExternKadPort(true);
	// keep the list of used clients
}

void CUDPFirewallTester::AddPossibleTestContact(const CUInt128 &uClientID, uint32 uIp, uint16 uUdpPort, uint16 uTcpPort, const CUInt128 &uTarget, uint8 uVersion, CKadUDPKey cUDPKey, bool bIPVerified){
	if (!IsFWCheckUDPRunning())
		return;
	// add the possible contact to our list - no checks in advance
	m_liPossibleTestClients.AddHead(CContact(uClientID, uIp, uUdpPort, uTcpPort, uTarget, uVersion, cUDPKey, bIPVerified));
	QueryNextClient();
}

void CUDPFirewallTester::QueryNextClient(){ // try the next available client for the firewallcheck
	
	if (!IsFWCheckUDPRunning() || !GetUDPCheckClientsNeeded() || CKademlia::GetPrefs()->GetExternalKadPort() == 0)
		return; // check if more tests are needed and wait till we know our extern port

	if (!CKademlia::IsRunning() || CKademlia::GetRoutingZone() == NULL){
		ASSERT( false );
		return;
	}

	while (!m_liPossibleTestClients.IsEmpty()){
		CContact curContact = m_liPossibleTestClients.RemoveHead();
		// udp firewallchecks are not supported by clients with kadversion < 6
		if (curContact.GetVersion() <= KADEMLIA_VERSION5_48a)
			continue;

		// sanitize - do not test ourself
		if (ntohl(curContact.GetIPAddress()) == theApp.GetPublicIP() || curContact.GetClientID().CompareTo(CKademlia::GetPrefs()->GetKadID()) == 0)
			continue;

		// check if we actually requested a firewallcheck from this client at some point
		bool bAlreadyRequested = false;
		for (POSITION pos = m_liUsedTestClients.GetHeadPosition(); pos != NULL;){
			if (m_liUsedTestClients.GetNext(pos).contact.GetIPAddress() == curContact.GetIPAddress()){
				bAlreadyRequested = true;
				break;
			}
		}
		// check if we know itsIP already from kademlia - we need an IP which was never used for UDP yet
		if (!bAlreadyRequested && CKademlia::GetRoutingZone()->GetContact(curContact.GetIPAddress(), 0, false) == NULL){
			// ok, tell the clientlist to do the same search and start the check if ok
			if (theApp.clientlist->DoRequestFirewallCheckUDP(curContact)){
				UsedClient_Struct sAdd = { curContact, false };
				m_liUsedTestClients.AddHead(sAdd);
				m_byFWChecksRunningUDP++;
				break;
			}
		}
	}
}