1 /*

     2 * Copyright (c) 2002-2009 Nokia Corporation and/or its subsidiary(-ies).

     3 * All rights reserved.

     4 * This component and the accompanying materials are made available

     5 * under the terms of the License "Eclipse Public License v1.0"

     6 * which accompanies this distribution, and is available

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

     8 *

     9 * Initial Contributors:

    10 * Nokia Corporation - initial contribution.

    11 *

    12 * Contributors:

    13 *

    14 * Description: 

    15 * This file contains the implementation for class encoding bit strings in ASN1 DER.

    16 *

    17 */

    18 

    19 

    20 

    21 

    22 /**

    23  @file

    24 */

    25 

    26 #include <asn1enc.h>

    27 

    28 EXPORT_C CASN1EncBitString* CASN1EncBitString::NewLC(const TDesC8& aBitStr)

    29 	{

    30 	CASN1EncBitString* self = new (ELeave) CASN1EncBitString();

    31 	CleanupStack::PushL(self);

    32 	self->ConstructL(aBitStr);

    33 	return self;

    34 	}

    35 

    36 EXPORT_C CASN1EncBitString* CASN1EncBitString::NewL(const TDesC8& aBitStr)

    37 	{

    38 	CASN1EncBitString* self = NewLC(aBitStr);

    39 	CleanupStack::Pop(self);

    40 	return self;

    41 	}

    42 

    43 EXPORT_C CASN1EncBitString* CASN1EncBitString::NewLC(const TDesC8& aBitStr, 

    44 													 TUint aLengthBits)

    45 	{

    46 	CASN1EncBitString* self = new (ELeave) CASN1EncBitString();

    47 	CleanupStack::PushL(self);

    48 	self->ConstructL(aBitStr, aLengthBits);

    49 	return self;

    50 	}

    51 

    52 EXPORT_C CASN1EncBitString* CASN1EncBitString::NewL(const TDesC8& aBitStr, 

    53 													TUint aLengthBits)

    54 	{

    55 	CASN1EncBitString* self = NewLC(aBitStr, aLengthBits);

    56 	CleanupStack::Pop(self);

    57 	return self;

    58 	}

    59 

    60 EXPORT_C CASN1EncBitString* CASN1EncBitString::NewL(const CASN1EncBase& aEncObj)

    61 	{

    62 	CASN1EncBitString* self = NewLC(aEncObj);

    63 	CleanupStack::Pop(self);

    64 	return self;

    65 	}

    66 

    67 EXPORT_C CASN1EncBitString* CASN1EncBitString::NewLC(const CASN1EncBase& aEncObj)

    68 	{

    69 	CASN1EncBitString* self = new (ELeave) CASN1EncBitString();

    70 	CleanupStack::PushL(self);

    71 	self->ConstructL(aEncObj);

    72 	return self;

    73 	}

    74 

    75 EXPORT_C CASN1EncBitString::~CASN1EncBitString()

    76 	{

    77 	delete iContents;

    78 	}

    79 

    80 CASN1EncBitString::CASN1EncBitString()

    81 : CASN1EncPrimitive(EASN1BitString),

    82   iPadding(0)

    83 	{

    84 	}

    85 

    86 void CASN1EncBitString::ConstructL(const TDesC8& aBitStr)

    87 	{

    88 	iContents = aBitStr.AllocL();

    89 	CASN1EncPrimitive::ConstructL();

    90 	}

    91 

    92 void CASN1EncBitString::ConstructL(const TDesC8& aBitStr, TUint aLengthBits)

    93 	{

    94 	iContents = aBitStr.AllocL();

    95 	CASN1EncPrimitive::ConstructL();

    96 	TUint totalBits = aBitStr.Length() * 8;

    97 	__ASSERT_ALWAYS(aLengthBits <= totalBits, User::Leave(KErrArgument));

    98 	iPadding = (TUint8)(totalBits - aLengthBits);

    99 	if(iPadding > 7)

   100 		User::Leave(KErrArgument);

   101 	}

   102 

   103 /**

   104  * @internalTechnology

   105  * Constructs bit string from ASN.1 encoding object.

   106  * @param aEncObj ASN.1 encoding object to wrap in bit string.

   107  * @note First produces raw DER encoding from the object, then creates 

   108  *     a bit string using other construct function.

   109  */

   110 void CASN1EncBitString::ConstructL(const CASN1EncBase& aEncObj)

   111 	{

   112 	// produce raw DER encoding from the created ASN.1 encoding

   113 	TUint len = aEncObj.LengthDER();

   114 	HBufC8* intDer = HBufC8::NewMaxLC(len);

   115 	TPtr8 ptrDer = intDer->Des();

   116 	TUint pos = 0;

   117 	aEncObj.WriteDERL(ptrDer, pos);

   118 	// wrap the produced DER encoding into a bit string

   119 	ConstructL(*intDer);

   120 	// cleanup

   121 	CleanupStack::PopAndDestroy(intDer);

   122 	}

   123 

   124 /** 

   125  * @internalTechnology 

   126  * Calculates length of DER-encoded bit string contents. For non empty

   127  * bit strings this differs from octet string in the extra leading byte 

   128  * containing the number of unused bits in the last octet.

   129  */

   130 void CASN1EncBitString::CalculateContentsLengthDER()

   131 	{

   132 	iContentsLengthDER = iContents->Length();

   133 	if (iContentsLengthDER > 0)

   134 		{

   135 		iContentsLengthDER++;

   136 		}

   137 	}

   138 

   139 /**

   140  * @internalTechnology 

   141  * Writes DER-encoded bit string contents to aBuf. Prepends 

   142  * the actual bit string octets with extra octet containing 

   143  * number of unused bits in the last octet. Before writing, 

   144  * converts contents of the bit string to big-endian form.

   145  * @param aBuf Buffer to write to; must be long enough; 

   146  *     see #CalculateContentsLengthDER method.

   147  */

   148 void CASN1EncBitString::WriteContentsDERL(TDes8& aBuf) const

   149 	{

   150 	if (iContents->Length() > 0)

   151 		{

   152 		aBuf[0] = iPadding;

   153 		TUint len = iContents->Length();

   154 		// We do not need to swap bits, as it is already done.

   155 		aBuf.Replace(1, len, *iContents);		

   156 		}

   157 	else

   158 		{

   159 		// no padding octet for the empty bit string

   160 		aBuf.SetLength(0);

   161 		}

   162 	}