www.pudn.com > truecrypt.zip > CACHE.C

/* Copyright (C) 2004 TrueCrypt Team, truecrypt.org 
   This product uses components written by Paul Le Roux  */ 
 
#include "tcdefs.h" 
 
#ifndef NT4_DRIVER 
#pragma VxD_LOCKED_CODE_SEG 
#pragma VxD_LOCKED_DATA_SEG 
#endif 
 
#include "crypto.h" 
#include "fat.h" 
#include "volumes.h" 
#include "apidrvr.h" 
 
#include "cache.h" 
 
#define CACHE_SIZE 4 
 
char szDriverPassword[CACHE_SIZE][MAX_PASSWORD + 1]; 
int nDriverPasswordLen[CACHE_SIZE]; 
int nPasswordIdx = 0; 
int cacheEmpty = 1; 
 
int 
VolumeReadHeaderCache (BOOL bCache, char *dev, char *lpszPassword, int nPasswordLen, 
		       PCRYPTO_INFO * retInfo) 
{ 
	int nReturnCode = ERR_PASSWORD_WRONG; 
	int i; 
 
	/* Attempt to recognize volume using mount password */ 
	if (nPasswordLen > 0) 
	{ 
		nReturnCode = VolumeReadHeader (dev, lpszPassword, retInfo); 
 
		/* Save mount passwords back into cache if asked to do so */ 
		if (bCache == TRUE && nReturnCode == 0) 
		{ 
			for (i = 0; i < CACHE_SIZE; i++) 
			{ 
				if (nDriverPasswordLen[i] > 0 && nDriverPasswordLen[i] == nPasswordLen && 
					memcmp (szDriverPassword[i], lpszPassword, nPasswordLen) == 0) 
					break; 
			} 
 
			if (i == CACHE_SIZE) 
			{ 
				/* Store the password */ 
				memcpy (szDriverPassword[nPasswordIdx], lpszPassword, nPasswordLen); 
 
				/* Add in the null as we made room for this */ 
				szDriverPassword[nPasswordIdx][nPasswordLen] = 0; 
 
				/* Save the length for later */ 
				nDriverPasswordLen[nPasswordIdx] = nPasswordLen; 
 
				/* Try another slot */ 
				nPasswordIdx = (nPasswordIdx + 1) % CACHE_SIZE; 
 
				cacheEmpty = 0; 
			} 
		} 
	} 
	else if (!cacheEmpty) 
	{ 
		/* Attempt to recognize volume using cached passwords */ 
		for (i = 0; i < CACHE_SIZE; i++) 
		{ 
			if (nDriverPasswordLen[i] > 0) 
			{ 
				nReturnCode = VolumeReadHeader (dev, szDriverPassword[i], retInfo); 
 
				if (nReturnCode != ERR_PASSWORD_WRONG) 
					break; 
			} 
 
		} 
	} 
 
	return nReturnCode; 
} 
 
void 
WipeCache () 
{ 
	burn (szDriverPassword, sizeof (szDriverPassword)); 
	burn (nDriverPasswordLen, sizeof (nDriverPasswordLen)); 
	nPasswordIdx = 0; 
	cacheEmpty = 1; 
}