/*
 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) 2013-2015 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 "Tcdefs.h"
#include "Crypto.h"
#include "Fat.h"
#include "Volumes.h"
#include "Apidrvr.h"
#include "Common.h"
#include "Cache.h"

Password CachedPasswords[CACHE_SIZE];
int	 CachedPim[CACHE_SIZE];
int cacheEmpty = 1;
static int nPasswordIdx = 0;

int ReadVolumeHeaderWCache (BOOL bBoot, BOOL bCache, BOOL bCachePim, char *header, Password *password, int pkcs5_prf, int pim, BOOL truecryptMode, PCRYPTO_INFO *retInfo)
{
	int nReturnCode = ERR_PASSWORD_WRONG;
	int i, effectivePim;

	/* Attempt to recognize volume using mount password */
	if (password->Length > 0)
	{
		nReturnCode = ReadVolumeHeader (bBoot, header, password, pkcs5_prf, pim, truecryptMode, retInfo, NULL);

		/* Save mount passwords back into cache if asked to do so */
		if (bCache && (nReturnCode == 0 || nReturnCode == ERR_CIPHER_INIT_WEAK_KEY))
		{
			for (i = 0; i < CACHE_SIZE; i++)
			{
				if (memcmp (&CachedPasswords[i], password, sizeof (Password)) == 0)
					break;
			}

			if (i == CACHE_SIZE)
			{
				/* Store the password */
				CachedPasswords[nPasswordIdx] = *password;

				/* Store also PIM if requested, otherwise set to default */
				if (bCachePim && (pim > 0))
					CachedPim[nPasswordIdx] = pim;
				else
					CachedPim[nPasswordIdx] = 0;

				/* Try another slot */
				nPasswordIdx = (nPasswordIdx + 1) % CACHE_SIZE;

				cacheEmpty = 0;
			}
			else if (bCachePim)
			{
				CachedPim[i] = pim > 0? pim : 0;
			}
		}
	}
	else if (!cacheEmpty)
	{
		/* Attempt to recognize volume using cached passwords */
		for (i = 0; i < CACHE_SIZE; i++)
		{
			if (CachedPasswords[i].Length > 0)
			{
				if (truecryptMode)
					effectivePim = 0;
				else if (pim == -1)
					effectivePim = CachedPim[i];
				else
					effectivePim = pim;
				nReturnCode = ReadVolumeHeader (bBoot, header, &CachedPasswords[i], pkcs5_prf, effectivePim, truecryptMode, retInfo, NULL);

				if (nReturnCode != ERR_PASSWORD_WRONG)
					break;
			}
		}
	}

	return nReturnCode;
}


void AddPasswordToCache (Password *password, int pim)
{
	int i;
	for (i = 0; i < CACHE_SIZE; i++)
	{
		if (memcmp (&CachedPasswords[i], password, sizeof (Password)) == 0)
			return;
	}

	CachedPasswords[nPasswordIdx] = *password;
	CachedPim[nPasswordIdx] = pim > 0? pim : 0;
	nPasswordIdx = (nPasswordIdx + 1) % CACHE_SIZE;
	cacheEmpty = 0;
}


void WipeCache ()
{
	burn (CachedPasswords, sizeof (CachedPasswords));
	burn (CachedPim, sizeof (CachedPim));
	nPasswordIdx = 0;
	cacheEmpty = 1;
}