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os/security/cryptoservices/certificateandkeymgmt/asn1/bitstrenc.cpp
author sl
Tue, 10 Jun 2014 14:32:02 +0200 (2014-06-10)
changeset 1 260cb5ec6c19
permissions -rw-r--r--
Update contrib. 
     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  @file

    22 */

    23 

    24 #include <asn1enc.h>

    25 

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

    27 	{

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

    29 	CleanupStack::PushL(self);

    30 	self->ConstructL(aBitStr);

    31 	return self;

    32 	}

    33 

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

    35 	{

    36 	CASN1EncBitString* self = NewLC(aBitStr);

    37 	CleanupStack::Pop(self);

    38 	return self;

    39 	}

    40 

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

    42 													 TUint aLengthBits)

    43 	{

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

    45 	CleanupStack::PushL(self);

    46 	self->ConstructL(aBitStr, aLengthBits);

    47 	return self;

    48 	}

    49 

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

    51 													TUint aLengthBits)

    52 	{

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

    54 	CleanupStack::Pop(self);

    55 	return self;

    56 	}

    57 

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

    59 	{

    60 	CASN1EncBitString* self = NewLC(aEncObj);

    61 	CleanupStack::Pop(self);

    62 	return self;

    63 	}

    64 

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

    66 	{

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

    68 	CleanupStack::PushL(self);

    69 	self->ConstructL(aEncObj);

    70 	return self;

    71 	}

    72 

    73 EXPORT_C CASN1EncBitString::~CASN1EncBitString()

    74 	{

    75 	delete iContents;

    76 	}

    77 

    78 CASN1EncBitString::CASN1EncBitString()

    79 : CASN1EncPrimitive(EASN1BitString),

    80   iPadding(0)

    81 	{

    82 	}

    83 

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

    85 	{

    86 	iContents = aBitStr.AllocL();

    87 	CASN1EncPrimitive::ConstructL();

    88 	}

    89 

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

    91 	{

    92 	iContents = aBitStr.AllocL();

    93 	CASN1EncPrimitive::ConstructL();

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

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

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

    97 	if(iPadding > 7)

    98 		User::Leave(KErrArgument);

    99 	}

   100 

   101 /**

   102  * @internalTechnology

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

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

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

   106  *     a bit string using other construct function.

   107  */

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

   109 	{

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

   111 	TUint len = aEncObj.LengthDER();

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

   113 	TPtr8 ptrDer = intDer->Des();

   114 	TUint pos = 0;

   115 	aEncObj.WriteDERL(ptrDer, pos);

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

   117 	ConstructL(*intDer);

   118 	// cleanup

   119 	CleanupStack::PopAndDestroy(intDer);

   120 	}

   121 

   122 /** 

   123  * @internalTechnology 

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

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

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

   127  */

   128 void CASN1EncBitString::CalculateContentsLengthDER()

   129 	{

   130 	iContentsLengthDER = iContents->Length();

   131 	if (iContentsLengthDER > 0)

   132 		{

   133 		iContentsLengthDER++;

   134 		}

   135 	}

   136 

   137 /**

   138  * @internalTechnology 

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

   140  * the actual bit string octets with extra octet containing 

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

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

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

   144  *     see #CalculateContentsLengthDER method.

   145  */

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

   147 	{

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

   149 		{

   150 		aBuf[0] = iPadding;

   151 		TUint len = iContents->Length();

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

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

   154 		}

   155 	else

   156 		{

   157 		// no padding octet for the empty bit string

   158 		aBuf.SetLength(0);

   159 		}

   160 	}
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