// Copyright (c) 2006-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "Eclipse Public License v1.0"

// which accompanies this distribution, and is available

// at the URL "http://www.eclipse.org/legal/epl-v10.html".

//

// Initial Contributors:

// Nokia Corporation - initial contribution.

//

// Contributors:

//

// Description:

//

/**

 @file

 @internalComponent

*/

#include <bluetooth/logger.h>

#include "L2CapFecNegotiator.h"

#include "L2CapPDU.h"

static TBool operator<=(TL2CapChannelMode aLeft, TL2CapChannelMode aRight);

template<typename T> static inline TBool IsWithinBounds(const T aValue, const T aLeftBound, const T aRightBound);

#ifdef __FLOG_ACTIVE

_LIT8(KLogComponent, LOG_COMPONENT_L2CAP);

#endif

//

// Mode-specific handlers

//

TBool TModeSpecificFecOptionHandlerBase::BuildPositiveResponse(TRetransmissionAndFlowControlOption& aPreferred,

															   const TRetransmissionAndFlowControlOption& aPeer) const

	{

	LOG_FUNC

	// As simple as that according to the general negotiation process, i.e. not when negotiating

	// the 2.1 Core Spec Addendum 1 - introduced modes.

	aPreferred = aPeer;

	// Don't include the exactly same FEC in response.

	return EFalse;

	}

void TModeSpecificFecOptionHandlerBase::BuildNegativeResponse(TRetransmissionAndFlowControlOption& /*aPreferred*/,

															  const TRetransmissionAndFlowControlOption& /*aPeer*/) const

	{

	LOG_FUNC

	// Just send what we've got in Preferred.

	}

void TModeSpecificFecOptionHandlerBase::BuildRequestBasedOnUnacceptableParamsResponse(

											TRetransmissionAndFlowControlOption& aPreferred,

											const TRetransmissionAndFlowControlOption& aPeer,

											const TL2CapFecNegotiator& aFecNegotiator) const

	{

	LOG_FUNC

	// In general the only negotiable parameter is channel mode - that's what we should

	// take from the suggested response passed here in aPeer. The rest of the parameters are

	// informative and we should use our own values, based on the mode - the remote can not

	// reject informative parameters.

	// Note on interop:

	// Unfortunately <= 9.4 Symbian code _WILL_ reject if e.g. we send a MaxTransmit value

	// which is greater than its own preference. To interoperate with those this method is

	// overridden in the Legacy handler.

	aPreferred = TRetransmissionAndFlowControlOption(aPeer.LinkMode(), ETrue);

	SetMaxTransmit(aPreferred, aFecNegotiator.MaxTransmit());

	ZeroUnspecifiedRequestFields(aPreferred);

	}

void TModeSpecificFecOptionHandlerBase::SetMaxTransmit(TRetransmissionAndFlowControlOption& aFecOption, TUint8 /*aMaxTransmit*/) const

	{

	LOG_FUNC

	aFecOption.SetMaxTransmit(0);

	}

void TModeSpecificFecOptionHandlerBase::PrepareImplicitPeerResponse(TRetransmissionAndFlowControlOption& aImplicitResponse,

																	const TRetransmissionAndFlowControlOption& aPreferred) const

	{

	LOG_FUNC

	aImplicitResponse = aPreferred;

	}

void TModeSpecificFecOptionHandlerBase::ZeroUnspecifiedRequestFields(TRetransmissionAndFlowControlOption& /*aFecOption*/) const

	{LOG_FUNC}

void TModeSpecificFecOptionHandlerBase::ZeroUnspecifiedResponseFields(TRetransmissionAndFlowControlOption& /*aFecOption*/) const

	{LOG_FUNC}

// Streaming Mode

TBool TStreamingFecHandler::IsOptionValid(const TRetransmissionAndFlowControlOption& aFecOption) const

	{

	LOG_FUNC

	return aFecOption.MaximumPDUSize() >= TRetransmissionAndFlowControlOption::KMinValidMaximumPDUSize;

	}

TBool TStreamingFecHandler::IsPeerResponseAcceptable(const TRetransmissionAndFlowControlOption& aPreferred,

													 const TRetransmissionAndFlowControlOption& aPeer) const

	{

	LOG_FUNC

	return aPeer.MaximumPDUSize() <= aPreferred.MaximumPDUSize();

	}

TBool TStreamingFecHandler::BuildPositiveResponse(TRetransmissionAndFlowControlOption& aPreferred,

												  const TRetransmissionAndFlowControlOption& aPeer) const

	{

	LOG_FUNC

	TRetransmissionAndFlowControlOption response = aPeer;

	// Trim MPS to our desired value.

	response.SetMaximumPDUSize(Min(TRetransmissionAndFlowControlOption::KDefaultMaximumPDUSize,

								   response.MaximumPDUSize()));

	// Zero the ignored fields no matter what peer sent us in them.

	ZeroUnspecifiedResponseFields(response);

	aPreferred = response;

	// Include the FEC in ConfigRsp.

	return ETrue;

	}

void TStreamingFecHandler::BuildNegativeResponse(TRetransmissionAndFlowControlOption& aPreferred,

                                                 const TRetransmissionAndFlowControlOption& /*aPeer*/) const

    {

    LOG_FUNC

    // Channel Mode has been already set and that's the parameter that what we're actually

    // rejecting. The rest is informational and should be set by the remote to its own

    // liking based on the mode proposed, so we _could_ set them to 0, but just in case

    // we're talking to a dumb peer - or a bit older version of my own code that wouldn't

    // accept 0s, for that matter - set them to sensible defaults.

    aPreferred = TRetransmissionAndFlowControlOption(aPreferred.LinkMode(), ETrue);

    ZeroUnspecifiedRequestFields(aPreferred);

    }

void TStreamingFecHandler::ZeroUnspecifiedRequestFields(TRetransmissionAndFlowControlOption& aFecOption) const

	{

	LOG_FUNC

	aFecOption.SetTxWindowSize(0);

	aFecOption.SetMaxTransmit(0);

	aFecOption.SetRetransmissionTimeout(0);

	aFecOption.SetMonitorTimeout(0);

	}

void TStreamingFecHandler::ZeroUnspecifiedResponseFields(TRetransmissionAndFlowControlOption& aFecOption) const

	{

	LOG_FUNC

	aFecOption.SetTxWindowSize(0);

	aFecOption.SetMaxTransmit(0);

	aFecOption.SetRetransmissionTimeout(0);

	aFecOption.SetMonitorTimeout(0);

	}

// Enhanced Retransmission Mode

TBool TErtmFecHandler::IsOptionValid(const TRetransmissionAndFlowControlOption& aFecOption) const

	{

	LOG_FUNC

	return aFecOption.MaximumPDUSize() >= TRetransmissionAndFlowControlOption::KMinValidMaximumPDUSize &&

		   aFecOption.TxWindowSize() >= TRetransmissionAndFlowControlOption::KMinValidTxWindowSize &&

		   aFecOption.TxWindowSize() <= TRetransmissionAndFlowControlOption::KMaxValidEnhancedTxWindowSize;

	}

TBool TErtmFecHandler::IsPeerResponseAcceptable(const TRetransmissionAndFlowControlOption& aPreferred,

												const TRetransmissionAndFlowControlOption& aPeer) const

	{

	LOG_FUNC

	return // MaxTransmit in response doesn't matter.

		   IsWithinBounds(aPeer.RetransmissionTimeout(),

				   		  TRetransmissionAndFlowControlOption::KMinAcceptableRetransmissionTimeout,

				   		  TRetransmissionAndFlowControlOption::KMaxAcceptableRetransmissionTimeout) &&

		   IsWithinBounds(aPeer.MonitorTimeout(),

				   		  TRetransmissionAndFlowControlOption::KMinAcceptableMonitorTimeout,

				   		  TRetransmissionAndFlowControlOption::KMaxAcceptableMonitorTimeout) &&

		   aPeer.TxWindowSize() <= aPreferred.TxWindowSize() &&

		   aPeer.MaximumPDUSize() <= aPreferred.MaximumPDUSize();

	}

TBool TErtmFecHandler::BuildPositiveResponse(TRetransmissionAndFlowControlOption& aPreferred,

											 const TRetransmissionAndFlowControlOption& aPeer) const

	{

	LOG_FUNC

	TRetransmissionAndFlowControlOption response = aPeer;

	// Peer sends us 0s in Retransmission and Monitor time-outs in Request and expects us

	// to send values for the timers we're going to use in the response.

	response.SetRetransmissionTimeout(TRetransmissionAndFlowControlOption::KDefaultRetransmissionTimeout);

	response.SetMonitorTimeout(TRetransmissionAndFlowControlOption::KDefaultMonitorTimeout);

	ZeroUnspecifiedResponseFields(response);

	// Trim TxWindow and MPS to our preferred values.

	response.SetTxWindowSize(Min(TRetransmissionAndFlowControlOption::KDefaultEnhancedTxWindowSize,

								 response.TxWindowSize()));

	response.SetMaximumPDUSize(Min(TRetransmissionAndFlowControlOption::KDefaultMaximumPDUSize,

								   response.MaximumPDUSize()));

	aPreferred = response;

	// Include the FEC in ConfigRsp.

	return ETrue;

	}

void TErtmFecHandler::BuildNegativeResponse(TRetransmissionAndFlowControlOption& aPreferred,

                                            const TRetransmissionAndFlowControlOption& /*aPeer*/) const

    {

    LOG_FUNC

    // Channel Mode has been already set and that's the parameter that what we're actually

    // rejecting. The rest is informational and should be set by the remote to its own

    // liking based on the mode proposed, so we _could_ set them to 0, but just in case

    // we're talking to a dumb peer - or a bit older version of my own code that wouldn't

    // accept 0s, for that matter - set them to sensible defaults.

    aPreferred = TRetransmissionAndFlowControlOption(aPreferred.LinkMode(), ETrue);

    ZeroUnspecifiedRequestFields(aPreferred);

    }

void TErtmFecHandler::SetMaxTransmit(TRetransmissionAndFlowControlOption& aFecOption, TUint8 aMaxTransmit) const

	{

	aFecOption.SetMaxTransmit(aMaxTransmit);

	}

void TErtmFecHandler::PrepareImplicitPeerResponse(TRetransmissionAndFlowControlOption& aImplicitResponse,

												  const TRetransmissionAndFlowControlOption& aPreferred) const

	{

	LOG_FUNC

	TModeSpecificFecOptionHandlerBase::PrepareImplicitPeerResponse(aImplicitResponse, aPreferred);

	// Peer is supposed to send us time-out values that it will use. It should always send

	// a response FEC if we're negotiating enhanced modes, so eventually we will get the real

	// values (unless the peer is broken).

	aImplicitResponse.SetRetransmissionTimeout(TRetransmissionAndFlowControlOption::KDefaultRetransmissionTimeout);

	aImplicitResponse.SetMonitorTimeout(TRetransmissionAndFlowControlOption::KDefaultMonitorTimeout);

	}

void TErtmFecHandler::ZeroUnspecifiedRequestFields(TRetransmissionAndFlowControlOption& aFecOption) const

	{

	aFecOption.SetRetransmissionTimeout(0);

	aFecOption.SetMonitorTimeout(0);

	}

void TErtmFecHandler::ZeroUnspecifiedResponseFields(TRetransmissionAndFlowControlOption& aFecOption) const

	{

	aFecOption.SetMaxTransmit(0);

	}

// Flow Control Mode and Retransmission Mode

TBool TLegacyFecHandler::IsOptionValid(const TRetransmissionAndFlowControlOption& aFecOption) const

	{

	LOG_FUNC

	return aFecOption.MaximumPDUSize() >= TRetransmissionAndFlowControlOption::KMinValidMaximumPDUSize &&

		   aFecOption.TxWindowSize() >= TRetransmissionAndFlowControlOption::KMinValidTxWindowSize &&

		   aFecOption.TxWindowSize() <= TRetransmissionAndFlowControlOption::KMaxValidLegacyTxWindowSize &&

		   aFecOption.MaxTransmit() >= TRetransmissionAndFlowControlOption::KMinValidNumberTransmit &&

		   aFecOption.MaxTransmit() <= TRetransmissionAndFlowControlOption::KMaxValidLegacyNumberTransmit;

	}

TBool TLegacyFecHandler::IsPeerResponseAcceptable(const TRetransmissionAndFlowControlOption& aPreferred,

												  const TRetransmissionAndFlowControlOption& aPeer) const

	{

	LOG_FUNC

	return aPeer == aPreferred;

	}

void TLegacyFecHandler::SetMaxTransmit(TRetransmissionAndFlowControlOption& aFecOption, TUint8 aMaxTransmit) const

	{

	aFecOption.SetMaxTransmit(aMaxTransmit == TRetransmissionAndFlowControlOption::KMaxValidEnhancedNumberTransmit ?

							  TRetransmissionAndFlowControlOption::KMaxValidLegacyNumberTransmit :

							  aMaxTransmit);

	}

void TLegacyFecHandler::BuildRequestBasedOnUnacceptableParamsResponse(

		TRetransmissionAndFlowControlOption& aPreferred,

		const TRetransmissionAndFlowControlOption& aPeer,

		const TL2CapFecNegotiator& aFecNegotiator) const

    {

    LOG_FUNC

	// In general the only negotiable parameter is channel mode - that's what we should

	// take from the suggested response passed here in aPeer. The rest of the parameters are

	// informative and we should use our own values, based on the mode - the remote can not

	// reject informative parameters.

	//

	// HOWEVER:

	//

	// Unfortunately <= 9.4 Symbian code _WILL_ reject if e.g. we send a MaxTransmit value

	// which is greater than its own preference. To interoperate with those we take

	// the whole FEC option suggested by the remote, including the informational parameters.

	// <= 9.4 Symbian devices implement RTM and FC modes (and not ERTM and Streaming).

	// Additionally, pretty much noone else in the market does - most people jumped from

	// Basic straight to ERTM & Streaming. So it can be assumed that:

	// Legacy (RTM & FC) ~= pre-ERTM Symbian. 

	typedef TRetransmissionAndFlowControlOption TFec;	// just 'coz I'm lazy

	// Use the remote's whole suggestion if all informational parameters look edible ...

	if (aPeer.TxWindowSize()          >= TFec::KMinValidTxWindowSize &&

		aPeer.MaxTransmit()           >= TFec::KMinValidNumberTransmit &&

		aPeer.RetransmissionTimeout() >= TFec::KMinAcceptableRetransmissionTimeout &&

		aPeer.MonitorTimeout()        >= TFec::KMinAcceptableMonitorTimeout &&

		aPeer.MaximumPDUSize()        >= TFec::KMinValidMaximumPDUSize)

		{

		aPreferred = aPeer;

		}

	else // ... otherwise only use channel mode to prevent DoS attacks.

		{

		aPreferred = TRetransmissionAndFlowControlOption(aPeer.LinkMode(), ETrue);

		SetMaxTransmit(aPreferred, aFecNegotiator.MaxTransmit());

		ZeroUnspecifiedRequestFields(aPreferred);

		}

	}

// Basic mode

TBool TBasicFecHandler::IsOptionValid(const TRetransmissionAndFlowControlOption& /*aFecOption*/) const

	{

	LOG_FUNC

	// Only the mode field is specified for Basic, and we know the mode is Basic already...

	return ETrue;

	}

TBool TBasicFecHandler::IsPeerResponseAcceptable(const TRetransmissionAndFlowControlOption& /*aPreferred*/,

												 const TRetransmissionAndFlowControlOption& /*aPeer*/) const

	{

	LOG_FUNC

	// Only the mode field is specified for Basic, and we know the mode is Basic already...

	return ETrue;

	}

// TFecOptionHandlerDelegator

TModeSpecificFecOptionHandlerBase& TFecOptionHandlerDelegator::Handler(const TRetransmissionAndFlowControlOption& aFecOption)

	{

	TModeSpecificFecOptionHandlerBase* handler = ModeToHandler(aFecOption.LinkMode());

	__ASSERT_ALWAYS(handler != NULL, Panic(EL2CAPUnknownChannelMode));

	return *handler;

	}

const TModeSpecificFecOptionHandlerBase& TFecOptionHandlerDelegator::Handler(const TRetransmissionAndFlowControlOption &aFecOption) const

	{

	const TModeSpecificFecOptionHandlerBase* handler = ModeToHandler(aFecOption.LinkMode());

	__ASSERT_ALWAYS(handler != NULL, Panic(EL2CAPUnknownChannelMode));

	return *handler;

	}

TModeSpecificFecOptionHandlerBase* TFecOptionHandlerDelegator::ModeToHandler(TL2CapChannelMode aMode)

	{

	TModeSpecificFecOptionHandlerBase* processor = 0;

	switch (aMode)

		{

		case EL2CAPStreamingMode:

			processor = &iStreamingFecHandler;

			break;

		case EL2CAPEnhancedRetransmissionMode:

			processor = &iErtmFecHandler;

			break;

		case EL2CAPRetransmissionMode:

		case EL2CAPFlowControlMode:

			processor = &iLegacyFecHandler;

			break;

		case EL2CAPBasicMode:

			processor = &iBasicFecHandler;

			break;

		default:

			break;

			// yes, return NULL.

		}

	return processor;

	}

const TModeSpecificFecOptionHandlerBase* TFecOptionHandlerDelegator::ModeToHandler(TL2CapChannelMode aMode) const

	{

	return const_cast<TFecOptionHandlerDelegator&>(*this).ModeToHandler(aMode);

	}

#ifdef __FLOG_ACTIVE

void TFecOptionHandlerDelegator::LogCurrentValues(const TRetransmissionAndFlowControlOption& aPreferred,

												  const TRetransmissionAndFlowControlOption& aPeer) const

	{

	TBuf<TRetransmissionAndFlowControlOption::KReadableDesSpaceRequired> buf;

	aPeer.GetReadable(buf);

	LOG1(_L("\tCurrent Peer: %S"), &buf)

	buf.Zero();

	aPreferred.GetReadable(buf);

	LOG1(_L("\tCurrent Preferred: %S"), &buf)

	}

#endif

//

// TL2CapSingleDirectionFecNegotiatorBase

//

void TL2CapSingleDirectionFecNegotiatorBase::SetupForRenegotiation()

	{

	LOG_FUNC

	if (iFecNegotiator.DesiredMode() == EL2CAPBasicMode &&

		// Only skip negotiating Basic if it still is the last accepted value.

		iPeer.LinkMode() == EL2CAPBasicMode)

		{

		// See comment in Setup().

		iConfigStatus = EOptionConfigComplete;

		}

#ifdef __FLOG_ACTIVE

	LogState();

#endif

	}

TBool TL2CapSingleDirectionFecNegotiatorBase::IsPeerModeAcceptable(TL2CapChannelMode aPeerMode,

																   TBool& aDisconnect) const

	{

	LOG_FUNC

	TBool acceptable = ETrue;

	aDisconnect = EFalse;

	LOG3(_L("\tNegotiation Behavior = %d, Desired Mode = %d, Peer Mode = %d"),

		 iFecNegotiator.NegotiationBehavior(), iFecNegotiator.DesiredMode(), aPeerMode)

	if (iFecNegotiator.NegotiationBehavior() == TL2CapFecNegotiator::EState2)

		{

		if (iFecNegotiator.DesiredMode() != aPeerMode)

			{

			// Game over.

			acceptable = EFalse;

			aDisconnect = ETrue;

			}

		}

	else // some sort of State 1

		{

		// A safety net - check that it's legal for our peer to propose this mode.

		if (!iFecNegotiator.IsModeLegal(aPeerMode))

			{

			// Remote is behaving out of spec.

			acceptable = EFalse;

			LOG1(_L("Peer proposed an illegal mode = %d"), aPeerMode);

			}

		else

			{

			// Check that the mode is within our limits according to the spec-defined precedence

			// hierarchy. Note that the spec only defines the precedence and State 1/2 algorithm

			// for the new modes + Basic, but we try and apply it to the legacy modes as well for

			// predictable & consistent behavior.

			acceptable = aPeerMode <= iFecNegotiator.DesiredMode();

			// Now, the State 1 algorithm gives us two choices in case peer proposes a mode

			// that's higher precedence than our desired mode (aPeerMode < iDesiredMode) -

			// - we can either accept it or close the connection - we cannot propose a different

			// one. EState1NoUnreliableToReliable means we do not want to allow fallback from an

			// unreliable mode to a reliable one, i.e. when we propose an unreliable mode,

			// but the remote proposes a reliable one (ERTM is higher prec. than Streaming,

			// ditto RTM vs FC).

			if (acceptable && iFecNegotiator.NegotiationBehavior() == TL2CapFecNegotiator::EState1NoUnreliableToReliable &&

				(iFecNegotiator.DesiredMode() == EL2CAPStreamingMode || iFecNegotiator.DesiredMode() == EL2CAPFlowControlMode) &&

				(aPeerMode == EL2CAPEnhancedRetransmissionMode || aPeerMode == EL2CAPRetransmissionMode))

				{

				acceptable = EFalse;

				if (!(iFecNegotiator.DesiredMode() == EL2CAPFlowControlMode && aPeerMode == EL2CAPRetransmissionMode))

					{

					// Only disconnect immediately if the peer seems to be implementing enhanced

					// modes - mostly to be interoperable with pre-2.1 Core Spec Addendum 1 Symbian

					// code, which doesn't handle disconnects well when there're still unresponded

					// request commands.

					// If we don't disconnect, a FEC for our desired mode will be sent, and we'll

					// see what happens - free style negotiation is allowed with legacy remotes.

					aDisconnect = ETrue;

					}

				LOG(_L("\tRefusing to fall back from Unreliable to Reliable"));

				}

			}

		} // State 1

	LOG2(_L("\tPeer channel mode acceptable = %d, disconnect required = %d"), acceptable, aDisconnect);

	return acceptable;

	}

#ifdef __FLOG_ACTIVE

void TL2CapSingleDirectionFecNegotiatorBase::LogState() const

	{

	LOG3(_L("\tdesired channel mode = %d, mode negotiation behavior = %d, config status = %d"),

			iFecNegotiator.DesiredMode(), iFecNegotiator.NegotiationBehavior(), iConfigStatus)

	TBuf<TRetransmissionAndFlowControlOption::KReadableDesSpaceRequired> readable;

	iPreferred.GetReadable(readable);

	LOG1(_L("\tpreferred FEC = %S"), &readable);

	readable.Zero();

	iPeer.GetReadable(readable);

	LOG1(_L("\tpeer FEC = %S"), &readable);

	}

#endif

//

// TL2CapIncomingFecNegotiator

//

void TL2CapIncomingFecNegotiator::Setup()

    {

    LOG_FUNC

    // Set up spec default as initial peer value.

    iPeer = TRetransmissionAndFlowControlOption();

    // Set up our initial request.

    BuildRequest(iFecNegotiator.DesiredMode(), iPreferred);

    if (iFecNegotiator.DesiredMode() == EL2CAPBasicMode)

        {

        // Basic mode is the implicit default, so it's complete unless peer says otherwise.

        // Besides, the fact that Basic is our desired mode normally means that the peer doesn't

        // support anything else, so it would not be able to parse a TRetransmissionAndFlowControl

        // option if we sent it.

        iConfigStatus = EOptionConfigComplete;

        }

#ifdef __FLOG_ACTIVE

    LogState();

#endif

    }

void TL2CapIncomingFecNegotiator::ProcessPeerValue(const TRetransmissionAndFlowControlOption& aFecOption,

												   TBool aIsUnacceptableParameters)

	{

	LOG_FUNC

	iPeer = aFecOption;

	// 'return' parameter from IsPeerModeAcceptable() - we'll ignore it because in

	// incoming direction we disconnect if response config status is failed anyway.

	TBool disconnect;