/*
 Legal Notice: Some portions of the source code contained in this file were
 derived from the source code of TrueCrypt 7.1a, which is 
 Copyright (c) 2003-2012 TrueCrypt Developers Association and which is 
 governed by the TrueCrypt License 3.0, also from the source code of
 Encryption for the Masses 2.02a, which is Copyright (c) 1998-2000 Paul Le Roux
 and which is governed by the 'License Agreement for Encryption for the Masses' 
 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 <stdlib.h>
#include <string.h>
#include <time.h>

#include "Tcdefs.h"

#include "Crypto.h"
#include "Common/Endian.h"
#include "Format.h"
#include "Fat.h"
#include "Progress.h"
#include "Random.h"
#include "Volumes.h"

void
GetFatParams (fatparams * ft)
{
	uint64 volumeSize = (uint64) ft->num_sectors * ft->sector_size;
	unsigned int fatsecs;

	if(ft->cluster_size == 0)	// 'Default' cluster size
	{
		uint32 clusterSize;

		// Determine optimal cluster size to minimize FAT size (mounting delay), maximize number of files, keep 4 KB alignment, etc.
		if (volumeSize >= 2 * BYTES_PER_TB)
			clusterSize = 256 * BYTES_PER_KB;
		else if (volumeSize >= 512 * BYTES_PER_GB)
			clusterSize = 128 * BYTES_PER_KB;
		else if (volumeSize >= 128 * BYTES_PER_GB)
			clusterSize = 64 * BYTES_PER_KB;
		else if (volumeSize >= 64 * BYTES_PER_GB)
			clusterSize = 32 * BYTES_PER_KB;
		else if (volumeSize >= 32 * BYTES_PER_GB)
			clusterSize = 16 * BYTES_PER_KB;
		else if (volumeSize >= 16 * BYTES_PER_GB)
			clusterSize = 8 * BYTES_PER_KB;
		else if (volumeSize >= 512 * BYTES_PER_MB)
			clusterSize = 4 * BYTES_PER_KB;
		else if (volumeSize >= 256 * BYTES_PER_MB)
			clusterSize = 2 * BYTES_PER_KB;
		else if (volumeSize >= 1 * BYTES_PER_MB)
			clusterSize = 1 * BYTES_PER_KB;
		else
			clusterSize = 512;

		ft->cluster_size = clusterSize / ft->sector_size;
		
		if (ft->cluster_size == 0)
			ft->cluster_size = 1;

		if (((unsigned __int64) ft->cluster_size * ft->sector_size) > TC_MAX_FAT_CLUSTER_SIZE)
			ft->cluster_size = TC_MAX_FAT_CLUSTER_SIZE / ft->sector_size;

		if (ft->cluster_size > 128)
			ft->cluster_size = 128;
	}

	if (volumeSize <= TC_MAX_FAT_CLUSTER_SIZE * 4)
		ft->cluster_size = 1;

	// Geometry always set to SECTORS/1/1
	ft->secs_track = 1; 
	ft->heads = 1; 

	ft->dir_entries = 512;
	ft->fats = 2;
	ft->media = 0xf8;
	ft->hidden = 0;

	ft->size_root_dir = ft->dir_entries * 32;

	// FAT12
	ft->size_fat = 12;
	ft->reserved = 2;
	fatsecs = ft->num_sectors - (ft->size_root_dir + ft->sector_size - 1) / ft->sector_size - ft->reserved;
	ft->cluster_count = (int) (((unsigned __int64) fatsecs * ft->sector_size) / ((unsigned __int64) ft->cluster_size * ft->sector_size));
	ft->fat_length = (((ft->cluster_count * 3 + 1) >> 1) + ft->sector_size - 1) / ft->sector_size;

	if (ft->cluster_count >= 4085) // FAT16
	{
		ft->size_fat = 16;
		ft->reserved = 2;
		fatsecs = ft->num_sectors - (ft->size_root_dir + ft->sector_size - 1) / ft->sector_size - ft->reserved;
		ft->cluster_count = (int) (((__int64) fatsecs * ft->sector_size) / (ft->cluster_size * ft->sector_size));
		ft->fat_length = (ft->cluster_count * 2 + ft->sector_size - 1) / ft->sector_size;
	}
	
	if(ft->cluster_count >= 65525) // FAT32
	{
		ft->size_fat = 32;
		ft->reserved = 32 - 1;

		do
		{
			ft->reserved++;

			fatsecs = ft->num_sectors - ft->reserved;
			ft->size_root_dir = ft->cluster_size * ft->sector_size;
			ft->cluster_count = (int) (((unsigned __int64) fatsecs * ft->sector_size) / (ft->cluster_size * ft->sector_size));
			ft->fat_length = (ft->cluster_count * 4 + ft->sector_size - 1) / ft->sector_size;

		// Align data area on TC_MAX_VOLUME_SECTOR_SIZE

		} while (ft->sector_size == TC_SECTOR_SIZE_LEGACY
				&& (ft->reserved * ft->sector_size + ft->fat_length * ft->fats * ft->sector_size) % TC_MAX_VOLUME_SECTOR_SIZE != 0);
	}

	ft->cluster_count -= ft->fat_length * ft->fats / ft->cluster_size;

	if (ft->num_sectors >= 65536 || ft->size_fat == 32)
	{
		ft->sectors = 0;
		ft->total_sect = ft->num_sectors;
	}
	else
	{
		ft->sectors = (uint16) ft->num_sectors;
		ft->total_sect = 0;
	}
}

void
PutBoot (fatparams * ft, unsigned char *boot)
{
	int cnt = 0;

	boot[cnt++] = 0xeb;	/* boot jump */
	boot[cnt++] = 0x3c;
	boot[cnt++] = 0x90;
	memcpy (boot + cnt, "MSDOS5.0", 8); /* system id */
	cnt += 8;
	*(__int16 *)(boot + cnt) = LE16(ft->sector_size);	/* bytes per sector */
	cnt += 2;
	boot[cnt++] = (__int8) ft->cluster_size;			/* sectors per cluster */
	*(__int16 *)(boot + cnt) = LE16(ft->reserved);		/* reserved sectors */
	cnt += 2;
	boot[cnt++] = (__int8) ft->fats;					/* 2 fats */

	if(ft->size_fat == 32)
	{
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
	}
	else
	{
		*(__int16 *)(boot + cnt) = LE16(ft->dir_entries);	/* 512 root entries */
		cnt += 2;
	}

	*(__int16 *)(boot + cnt) = LE16(ft->sectors);		/* # sectors */
	cnt += 2;
	boot[cnt++] = (__int8) ft->media;					/* media byte */

	if(ft->size_fat == 32)	
	{
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
	}
	else 
	{ 
		*(__int16 *)(boot + cnt) = LE16((uint16) ft->fat_length);	/* fat size */
		cnt += 2;
	}

	*(__int16 *)(boot + cnt) = LE16(ft->secs_track);	/* # sectors per track */
	cnt += 2;
	*(__int16 *)(boot + cnt) = LE16(ft->heads);			/* # heads */
	cnt += 2;
	*(__int32 *)(boot + cnt) = LE32(ft->hidden);		/* # hidden sectors */
	cnt += 4;
	*(__int32 *)(boot + cnt) = LE32(ft->total_sect);	/* # huge sectors */
	cnt += 4;

	if(ft->size_fat == 32)
	{
		*(__int32 *)(boot + cnt) = LE32(ft->fat_length); cnt += 4;	/* fat size 32 */
		boot[cnt++] = 0x00;	/* ExtFlags */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;	/* FSVer */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x02;	/* RootClus */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x01;	/* FSInfo */
		boot[cnt++] = 0x00;
		boot[cnt++] = 0x06;	/* BkBootSec */
		boot[cnt++] = 0x00;
		memset(boot+cnt, 0, 12); cnt+=12;	/* Reserved */
	}

	boot[cnt++] = 0x00;	/* drive number */   // FIXED 80 > 00
	boot[cnt++] = 0x00;	/* reserved */
	boot[cnt++] = 0x29;	/* boot sig */

	memcpy (boot + cnt, ft->volume_id, 4);		/* vol id */
	cnt += 4;

	memcpy (boot + cnt, ft->volume_name, 11);	/* vol title */
	cnt += 11;

	switch(ft->size_fat) /* filesystem type */
	{
		case 12: memcpy (boot + cnt, "FAT12   ", 8); break;
		case 16: memcpy (boot + cnt, "FAT16   ", 8); break;
		case 32: memcpy (boot + cnt, "FAT32   ", 8); break;
	}
	cnt += 8;

	memset (boot + cnt, 0, ft->size_fat==32 ? 420:448);	/* boot code */
	cnt += ft->size_fat==32 ? 420:448;
	boot[cnt++] = 0x55;
	boot[cnt++] = 0xaa;	/* boot sig */
}


/* FAT32 FSInfo */
static void PutFSInfo (unsigned char *sector, fatparams *ft)
{
	memset (sector, 0, ft->sector_size);
	sector[3]=0x41; /* LeadSig */
	sector[2]=0x61; 
	sector[1]=0x52; 
	sector[0]=0x52; 
	sector[484+3]=0x61; /* StrucSig */
	sector[484+2]=0x41; 
	sector[484+1]=0x72; 
	sector[484+0]=0x72; 

	// Free cluster count
	*(uint32 *)(sector + 488) = LE32 (ft->cluster_count - ft->size_root_dir / ft->sector_size / ft->cluster_size);

	// Next free cluster
	*(uint32 *)(sector + 492) = LE32 (2);

	sector[508+3]=0xaa; /* TrailSig */
	sector[508+2]=0x55;
	sector[508+1]=0x00;
	sector[508+0]=0x00;
}


int
FormatFat (void* hwndDlgPtr, unsigned __int64 startSector, fatparams * ft, void * dev, PCRYPTO_INFO cryptoInfo, BOOL quickFormat)
{
	int write_buf_cnt = 0;
	char sector[TC_MAX_VOLUME_SECTOR_SIZE], *write_buf;
	unsigned __int64 nSecNo = startSector;
	int x, n;
	int retVal;
	char temporaryKey[MASTER_KEYDATA_SIZE];
	HWND hwndDlg = (HWND) hwndDlgPtr;

	LARGE_INTEGER startOffset;
	LARGE_INTEGER newOffset;

	// Seek to start sector
	startOffset.QuadPart = startSector * ft->sector_size;
	if (!SetFilePointerEx ((HANDLE) dev, startOffset, &newOffset, FILE_BEGIN)
		|| newOffset.QuadPart != startOffset.QuadPart)
	{
		return ERR_VOL_SEEKING;
	}

	/* Write the data area */

	write_buf = (char *)TCalloc (FormatWriteBufferSize);
	if (!write_buf)
		return ERR_OUTOFMEMORY;

	memset (sector, 0, ft->sector_size);

	if (!RandgetBytes (hwndDlg, ft->volume_id, sizeof (ft->volume_id), FALSE))
		goto fail;

	PutBoot (ft, (unsigned char *) sector);
	if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
		cryptoInfo) == FALSE)
		goto fail;

	/* fat32 boot area */
	if (ft->size_fat == 32)				
	{
		/* fsinfo */
		PutFSInfo((unsigned char *) sector, ft);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
			cryptoInfo) == FALSE)
			goto fail;

		/* reserved */
		while (nSecNo - startSector < 6)
		{
			memset (sector, 0, ft->sector_size);
			sector[508+3]=0xaa; /* TrailSig */
			sector[508+2]=0x55;
			if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				cryptoInfo) == FALSE)
				goto fail;
		}
		
		/* bootsector backup */
		memset (sector, 0, ft->sector_size);
		PutBoot (ft, (unsigned char *) sector);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				 cryptoInfo) == FALSE)
			goto fail;

		PutFSInfo((unsigned char *) sector, ft);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
			cryptoInfo) == FALSE)
			goto fail;
	}

	/* reserved */
	while (nSecNo - startSector < (unsigned int)ft->reserved)
	{
		memset (sector, 0, ft->sector_size);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
			cryptoInfo) == FALSE)
			goto fail;
	}

	/* write fat */
	for (x = 1; x <= ft->fats; x++)
	{
		for (n = 0; n < ft->fat_length; n++)
		{
			memset (sector, 0, ft->sector_size);

			if (n == 0)
			{
				unsigned char fat_sig[12];
				if (ft->size_fat == 32)
				{
					fat_sig[0] = (unsigned char) ft->media;
					fat_sig[1] = fat_sig[2] = 0xff;
					fat_sig[3] = 0x0f;
					fat_sig[4] = fat_sig[5] = fat_sig[6] = 0xff;
					fat_sig[7] = 0x0f;
					fat_sig[8] = fat_sig[9] = fat_sig[10] = 0xff;
					fat_sig[11] = 0x0f;
					memcpy (sector, fat_sig, 12);
				}				
				else if (ft->size_fat == 16)
				{
					fat_sig[0] = (unsigned char) ft->media;
					fat_sig[1] = 0xff;
					fat_sig[2] = 0xff;
					fat_sig[3] = 0xff;
					memcpy (sector, fat_sig, 4);
				}
				else if (ft->size_fat == 12)
				{
					fat_sig[0] = (unsigned char) ft->media;
					fat_sig[1] = 0xff;
					fat_sig[2] = 0xff;
					fat_sig[3] = 0x00;
					memcpy (sector, fat_sig, 4);
				}
			}

			if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				    cryptoInfo) == FALSE)
				goto fail;
		}
	}


	/* write rootdir */
	for (x = 0; x < ft->size_root_dir / ft->sector_size; x++)
	{
		memset (sector, 0, ft->sector_size);
		if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				 cryptoInfo) == FALSE)
			goto fail;

	}

	/* Fill the rest of the data area with random data */

	if(!quickFormat)
	{
		if (!FlushFormatWriteBuffer (dev, write_buf, &write_buf_cnt, &nSecNo, cryptoInfo))
			goto fail;

		/* Generate a random temporary key set to be used for "dummy" encryption that will fill
		the free disk space (data area) with random data.  This is necessary for plausible
		deniability of hidden volumes (and also reduces the amount of predictable plaintext
		within the volume). */

		// Temporary master key
		if (!RandgetBytes (hwndDlg, temporaryKey, EAGetKeySize (cryptoInfo->ea), FALSE))
			goto fail;

		// Temporary secondary key (XTS mode)
		if (!RandgetBytes (hwndDlg, cryptoInfo->k2, sizeof cryptoInfo->k2, FALSE))		
			goto fail;

		retVal = EAInit (cryptoInfo->ea, temporaryKey, cryptoInfo->ks);
		if (retVal != ERR_SUCCESS)
		{
			burn (temporaryKey, sizeof(temporaryKey));
			return retVal;
		}
		if (!EAInitMode (cryptoInfo))
		{
			burn (temporaryKey, sizeof(temporaryKey));
			return ERR_MODE_INIT_FAILED;
		}

		x = ft->num_sectors - ft->reserved - ft->size_root_dir / ft->sector_size - ft->fat_length * 2;
		while (x--)
		{
			if (WriteSector (dev, sector, write_buf, &write_buf_cnt, &nSecNo,
				cryptoInfo) == FALSE)
				goto fail;
		}
		UpdateProgressBar (nSecNo * ft->sector_size);
	}
	else
		UpdateProgressBar ((uint64) ft->num_sectors * ft->sector_size);

	if (!FlushFormatWriteBuffer (dev, write_buf, &write_buf_cnt, &nSecNo, cryptoInfo))
		goto fail;

	TCfree (write_buf);
	burn (temporaryKey, sizeof(temporaryKey));
	return 0;

fail:

	TCfree (write_buf);
	burn (temporaryKey, sizeof(temporaryKey));
	return ERR_OS_ERROR;
}