/*
 Derived from source code of TrueCrypt 7.1a, which is
 Copyright (c) 2008-2012 TrueCrypt Developers Association and which is governed
 by the TrueCrypt License 3.0.

 Modifications and additions to the original source code (contained in this file)
 and all other portions of this file are Copyright (c) 2013-2016 IDRIX
 and are governed by the Apache License 2.0 the full text of which is
 contained in the file License.txt included in VeraCrypt binary and source
 code distribution packages.
*/

#include "EncryptionThreadPool.h"
#include "Pkcs5.h"
#ifdef DEVICE_DRIVER
#include "Driver/Ntdriver.h"
#endif

#define TC_ENC_THREAD_POOL_MAX_THREAD_COUNT 64
#define TC_ENC_THREAD_POOL_QUEUE_SIZE (TC_ENC_THREAD_POOL_MAX_THREAD_COUNT * 2)

#ifdef DEVICE_DRIVER

#define TC_THREAD_HANDLE PKTHREAD
#define TC_THREAD_PROC VOID

#define TC_SET_EVENT(EVENT) KeSetEvent (&EVENT, IO_DISK_INCREMENT, FALSE)
#define TC_CLEAR_EVENT(EVENT) KeClearEvent (&EVENT)

#define TC_MUTEX FAST_MUTEX
#define TC_ACQUIRE_MUTEX(MUTEX) ExAcquireFastMutex (MUTEX)
#define TC_RELEASE_MUTEX(MUTEX) ExReleaseFastMutex (MUTEX)

#else // !DEVICE_DRIVER

#define TC_THREAD_HANDLE HANDLE
#define TC_THREAD_PROC unsigned __stdcall

#define TC_SET_EVENT(EVENT) SetEvent (EVENT)
#define TC_CLEAR_EVENT(EVENT) ResetEvent (EVENT)

#define TC_MUTEX HANDLE
#define TC_ACQUIRE_MUTEX(MUTEX) WaitForSingleObject (*(MUTEX), INFINITE)
#define TC_RELEASE_MUTEX(MUTEX) ReleaseMutex (*(MUTEX))

#endif // !DEVICE_DRIVER


typedef enum
{
	WorkItemFree,
	WorkItemReady,
	WorkItemBusy
} WorkItemState;


typedef struct EncryptionThreadPoolWorkItemStruct
{
	WorkItemState State;
	EncryptionThreadPoolWorkType Type;

	TC_EVENT ItemCompletedEvent;

	struct EncryptionThreadPoolWorkItemStruct *FirstFragment;
	LONG OutstandingFragmentCount;

	union
	{
		struct
		{
			PCRYPTO_INFO CryptoInfo;
			byte *Data;
			UINT64_STRUCT StartUnitNo;
			uint32 UnitCount;

		} Encryption;

		struct
		{
			TC_EVENT *CompletionEvent;
			LONG *CompletionFlag;
			char *DerivedKey;
			int IterationCount;
			TC_EVENT *NoOutstandingWorkItemEvent;
			LONG *OutstandingWorkItemCount;
			char *Password;
			int PasswordLength;
			int Pkcs5Prf;
			char *Salt;

		} KeyDerivation;
	};

} EncryptionThreadPoolWorkItem;


static volatile BOOL ThreadPoolRunning = FALSE;
static volatile BOOL StopPending = FALSE;

static uint32 ThreadCount;
static TC_THREAD_HANDLE ThreadHandles[TC_ENC_THREAD_POOL_MAX_THREAD_COUNT];

static EncryptionThreadPoolWorkItem WorkItemQueue[TC_ENC_THREAD_POOL_QUEUE_SIZE];

static volatile int EnqueuePosition;
static volatile int DequeuePosition;

static TC_MUTEX EnqueueMutex;
static TC_MUTEX DequeueMutex;

static TC_EVENT WorkItemReadyEvent;
static TC_EVENT WorkItemCompletedEvent;


static WorkItemState GetWorkItemState (EncryptionThreadPoolWorkItem *workItem)
{
	return InterlockedExchangeAdd ((LONG *) &workItem->State, 0);
}


static void SetWorkItemState (EncryptionThreadPoolWorkItem *workItem, WorkItemState newState)
{
	InterlockedExchange ((LONG *) &workItem->State, (LONG) newState);
}


static TC_THREAD_PROC EncryptionThreadProc (void *threadArg)
{
	EncryptionThreadPoolWorkItem *workItem;

	while (!StopPending)
	{
		TC_ACQUIRE_MUTEX (&DequeueMutex);

		workItem = &WorkItemQueue[DequeuePosition++];

		if (DequeuePosition >= TC_ENC_THREAD_POOL_QUEUE_SIZE)
			DequeuePosition = 0;

		while (!StopPending && GetWorkItemState (workItem) != WorkItemReady)
		{
			TC_WAIT_EVENT (WorkItemReadyEvent);
		}

		SetWorkItemState (workItem, WorkItemBusy);

		TC_RELEASE_MUTEX (&DequeueMutex);

		if (StopPending)
			break;

		switch (workItem->Type)
		{
		case DecryptDataUnitsWork:
			DecryptDataUnitsCurrentThread (workItem->Encryption.Data, &workItem->Encryption.StartUnitNo, workItem->Encryption.UnitCount, workItem->Encryption.CryptoInfo);
			break;

		case EncryptDataUnitsWork:
			EncryptDataUnitsCurrentThread (workItem->Encryption.Data, &workItem->Encryption.StartUnitNo, workItem->Encryption.UnitCount, workItem->Encryption.CryptoInfo);
			break;

		case DeriveKeyWork:
			switch (workItem->KeyDerivation.Pkcs5Prf)
			{
			case RIPEMD160:
				derive_key_ripemd160 (workItem->KeyDerivation.Password, workItem->KeyDerivation.PasswordLength, workItem->KeyDerivation.Salt, PKCS5_SALT_SIZE,
					workItem->KeyDerivation.IterationCount, workItem->KeyDerivation.DerivedKey, GetMaxPkcs5OutSize());
				break;

			case SHA512:
				derive_key_sha512 (workItem->KeyDerivation.Password, workItem->KeyDerivation.PasswordLength, workItem->KeyDerivation.Salt, PKCS5_SALT_SIZE,
					workItem->KeyDerivation.IterationCount, workItem->KeyDerivation.DerivedKey, GetMaxPkcs5OutSize());
				break;

			case WHIRLPOOL:
				derive_key_whirlpool (workItem->KeyDerivation.Password, workItem->KeyDerivation.PasswordLength, workItem->KeyDerivation.Salt, PKCS5_SALT_SIZE,
					workItem->KeyDerivation.IterationCount, workItem->KeyDerivation.DerivedKey, GetMaxPkcs5OutSize());
				break;

			case SHA256:
				derive_key_sha256 (workItem->KeyDerivation.Password, workItem->KeyDerivation.PasswordLength, workItem->KeyDerivation.Salt, PKCS5_SALT_SIZE,
					workItem->KeyDerivation.IterationCount, workItem->KeyDerivation.DerivedKey, GetMaxPkcs5OutSize());
				break;

			default:
				TC_THROW_FATAL_EXCEPTION;
			}

			InterlockedExchange (workItem->KeyDerivation.CompletionFlag, TRUE);
			TC_SET_EVENT (*workItem->KeyDerivation.CompletionEvent);

			if (InterlockedDecrement (workItem->KeyDerivation.OutstandingWorkItemCount) == 0)
				TC_SET_EVENT (*workItem->KeyDerivation.NoOutstandingWorkItemEvent);

			SetWorkItemState (workItem, WorkItemFree);
			TC_SET_EVENT (WorkItemCompletedEvent);
			continue;

		default:
			TC_THROW_FATAL_EXCEPTION;
		}

		if (workItem != workItem->FirstFragment)
		{
			SetWorkItemState (workItem, WorkItemFree);
			TC_SET_EVENT (WorkItemCompletedEvent);
		}

		if (InterlockedDecrement (&workItem->FirstFragment->OutstandingFragmentCount) == 0)
			TC_SET_EVENT (workItem->FirstFragment->ItemCompletedEvent);
	}

#ifdef DEVICE_DRIVER
	PsTerminateSystemThread (STATUS_SUCCESS);
#else
	_endthreadex (0);
    return 0;
#endif
}


BOOL EncryptionThreadPoolStart (size_t encryptionFreeCpuCount)
{
	size_t cpuCount, i;

	if (ThreadPoolRunning)
		return TRUE;

#ifdef DEVICE_DRIVER
	cpuCount = GetCpuCount();
#else
	{
		SYSTEM_INFO sysInfo;
		GetSystemInfo (&sysInfo);
		cpuCount = sysInfo.dwNumberOfProcessors;
	}
#endif

	if (cpuCount > encryptionFreeCpuCount)
		cpuCount -= encryptionFreeCpuCount;

	if (cpuCount < 2)
		return TRUE;

	if (cpuCount > TC_ENC_THREAD_POOL_MAX_THREAD_COUNT)
		cpuCount = TC_ENC_THREAD_POOL_MAX_THREAD_COUNT;

	StopPending = FALSE;
	DequeuePosition = 0;
	EnqueuePosition = 0;

#ifdef DEVICE_DRIVER
	KeInitializeEvent (&WorkItemReadyEvent, SynchronizationEvent, FALSE);
	KeInitializeEvent (&WorkItemCompletedEvent, SynchronizationEvent, FALSE);
#else
	WorkItemReadyEvent = CreateEvent (NULL, FALSE, FALSE, NULL);
	if (!WorkItemReadyEvent)
		return FALSE;

	WorkItemCompletedEvent = CreateEvent (NULL, FALSE, FALSE, NULL);
	if (!WorkItemCompletedEvent)
		return FALSE;
#endif

#ifdef DEVICE_DRIVER
	ExInitializeFastMutex (&DequeueMutex);
	ExInitializeFastMutex (&EnqueueMutex);
#else
	DequeueMutex = CreateMutex (NULL, FALSE, NULL);
	if (!DequeueMutex)
		return FALSE;

	EnqueueMutex = CreateMutex (NULL, FALSE, NULL);
	if (!EnqueueMutex)
		return FALSE;
#endif

	memset (WorkItemQueue, 0, sizeof (WorkItemQueue));

	for (i = 0; i < sizeof (WorkItemQueue) / sizeof (WorkItemQueue[0]); ++i)
	{
		WorkItemQueue[i].State = WorkItemFree;

#ifdef DEVICE_DRIVER
		KeInitializeEvent (&WorkItemQueue[i].ItemCompletedEvent, SynchronizationEvent, FALSE);
#else
		WorkItemQueue[i].ItemCompletedEvent = CreateEvent (NULL, FALSE, FALSE, NULL);
		if (!WorkItemQueue[i].ItemCompletedEvent)
		{
			EncryptionThreadPoolStop();
			return FALSE;
		}
#endif
	}

	for (ThreadCount = 0; ThreadCount < cpuCount; ++ThreadCount)
	{
#ifdef DEVICE_DRIVER
		if (!NT_SUCCESS (TCStartThread (EncryptionThreadProc, NULL, &ThreadHandles[ThreadCount])))
#else
		if (!(ThreadHandles[ThreadCount] = (HANDLE) _beginthreadex (NULL, 0, EncryptionThreadProc, NULL, 0, NULL)))
#endif
		{
			EncryptionThreadPoolStop();
			return FALSE;
		}
	}

	ThreadPoolRunning = TRUE;
	return TRUE;
}


void EncryptionThreadPoolStop ()
{
	size_t i;

	if (!ThreadPoolRunning)
		return;

	StopPending = TRUE;
	TC_SET_EVENT (WorkItemReadyEvent);

	for (i = 0; i < ThreadCount; ++i)
	{
#ifdef DEVICE_DRIVER
		TCStopThread (ThreadHandles[i], &WorkItemReadyEvent);
#else
		TC_WAIT_EVENT (ThreadHandles[i]);
#endif
	}

	ThreadCount = 0;

#ifndef DEVICE_DRIVER
	CloseHandle (DequeueMutex);
	CloseHandle (EnqueueMutex);

	CloseHandle (WorkItemReadyEvent);
	CloseHandle (WorkItemCompletedEvent);

	for (i = 0; i < sizeof (WorkItemQueue) / sizeof (WorkItemQueue[0]); ++i)
	{
		if (WorkItemQueue[i].ItemCompletedEvent)
			CloseHandle (WorkItemQueue[i].ItemCompletedEvent);
	}
#endif

	ThreadPoolRunning = FALSE;
}


void EncryptionThreadPoolBeginKeyDerivation (TC_EVENT *completionEvent, TC_EVENT *noOutstandingWorkItemEvent, LONG *completionFlag, LONG *outstandingWorkItemCount, int pkcs5Prf, char *password, int passwordLength, char *salt, int iterationCount, char *derivedKey)
{
	EncryptionThreadPoolWorkItem *workItem;

	if (!ThreadPoolRunning)
		TC_THROW_FATAL_EXCEPTION;

	TC_ACQUIRE_MUTEX (&EnqueueMutex);

	workItem = &WorkItemQueue[EnqueuePosition++];
	if (EnqueuePosition >= TC_ENC_THREAD_POOL_QUEUE_SIZE)
		EnqueuePosition = 0;

	while (GetWorkItemState (workItem) != WorkItemFree)
	{
		TC_WAIT_EVENT (WorkItemCompletedEvent);
	}

	workItem->Type = DeriveKeyWork;
	workItem->KeyDerivation.CompletionEvent = completionEvent;
	workItem->KeyDerivation.CompletionFlag = completionFlag;
	workItem->KeyDerivation.DerivedKey = derivedKey;
	workItem->KeyDerivation.IterationCount = iterationCount;
	workItem->KeyDerivation.NoOutstandingWorkItemEvent = noOutstandingWorkItemEvent;
	workItem->KeyDerivation.OutstandingWorkItemCount = outstandingWorkItemCount;
	workItem->KeyDerivation.Password = password;
	workItem->KeyDerivation.PasswordLength = passwordLength;
	workItem->KeyDerivation.Pkcs5Prf = pkcs5Prf;
	workItem->KeyDerivation.Salt = salt;

	InterlockedIncrement (outstandingWorkItemCount);
	TC_CLEAR_EVENT (*noOutstandingWorkItemEvent);

	SetWorkItemState (workItem, WorkItemReady);
	TC_SET_EVENT (WorkItemReadyEvent);
	TC_RELEASE_MUTEX (&EnqueueMutex);
}


void EncryptionThreadPoolDoWork (EncryptionThreadPoolWorkType type, byte *data, const UINT64_STRUCT *startUnitNo, uint32 unitCount, PCRYPTO_INFO cryptoInfo)
{
	uint32 fragmentCount;
	uint32 unitsPerFragment;
	uint32 remainder;

	byte *fragmentData;
	uint64 fragmentStartUnitNo;

	EncryptionThreadPoolWorkItem *workItem;
	EncryptionThreadPoolWorkItem *firstFragmentWorkItem;

	if (unitCount == 0)
		return;

	if (!ThreadPoolRunning || unitCount == 1)
	{
		switch (type)
		{
		case DecryptDataUnitsWork:
			DecryptDataUnitsCurrentThread (data, startUnitNo, unitCount, cryptoInfo);
			break;

		case EncryptDataUnitsWork:
			EncryptDataUnitsCurrentThread (data, startUnitNo, unitCount, cryptoInfo);
			break;

		default:
			TC_THROW_FATAL_EXCEPTION;
		}

		return;
	}

	if (unitCount <= ThreadCount)
	{
		fragmentCount = unitCount;
		unitsPerFragment = 1;
		remainder = 0;
	}
	else
	{
		/* Note that it is not efficient to divide the data into fragments smaller than a few hundred bytes.
		The reason is that the overhead associated with thread handling would in most cases make a multi-threaded
		process actually slower than a single-threaded process. */

		fragmentCount = ThreadCount;
		unitsPerFragment = unitCount / ThreadCount;
		remainder = unitCount % ThreadCount;

		if (remainder > 0)
			++unitsPerFragment;
	}

	fragmentData = data;
	fragmentStartUnitNo = startUnitNo->Value;

	TC_ACQUIRE_MUTEX (&EnqueueMutex);
	firstFragmentWorkItem = &WorkItemQueue[EnqueuePosition];

	while (GetWorkItemState (firstFragmentWorkItem) != WorkItemFree)
	{
		TC_WAIT_EVENT (WorkItemCompletedEvent);
	}

	firstFragmentWorkItem->OutstandingFragmentCount = fragmentCount;

	while (fragmentCount-- > 0)
	{
		workItem = &WorkItemQueue[EnqueuePosition++];
		if (EnqueuePosition >= TC_ENC_THREAD_POOL_QUEUE_SIZE)
			EnqueuePosition = 0;

		while (GetWorkItemState (workItem) != WorkItemFree)
		{
			TC_WAIT_EVENT (WorkItemCompletedEvent);
		}

		workItem->Type = type;
		workItem->FirstFragment = firstFragmentWorkItem;

		workItem->Encryption.CryptoInfo = cryptoInfo;
		workItem->Encryption.Data = fragmentData;
		workItem->Encryption.UnitCount = unitsPerFragment;
		workItem->Encryption.StartUnitNo.Value = fragmentStartUnitNo;

 		fragmentData += unitsPerFragment * ENCRYPTION_DATA_UNIT_SIZE;
		fragmentStartUnitNo += unitsPerFragment;

		if (remainder > 0 && --remainder == 0)
			--unitsPerFragment;

		SetWorkItemState (workItem, WorkItemReady);
		TC_SET_EVENT (WorkItemReadyEvent);
	}

	TC_RELEASE_MUTEX (&EnqueueMutex);

	TC_WAIT_EVENT (firstFragmentWorkItem->ItemCompletedEvent);
	SetWorkItemState (firstFragmentWorkItem, WorkItemFree);
	TC_SET_EVENT (WorkItemCompletedEvent);
}


size_t GetEncryptionThreadCount ()
{
	return ThreadPoolRunning ? ThreadCount : 0;
}


size_t GetMaxEncryptionThreadCount ()
{
	return TC_ENC_THREAD_POOL_MAX_THREAD_COUNT;
}


BOOL IsEncryptionThreadPoolRunning ()
{
	return ThreadPoolRunning;
}