genericservices/httputils/wspcodec/WSPDecoder.cpp
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     1 // Copyright (c) 2001-2009 Nokia Corporation and/or its subsidiary(-ies).
       
     2 // All rights reserved.
       
     3 // This component and the accompanying materials are made available
       
     4 // under the terms of "Eclipse Public License v1.0"
       
     5 // which accompanies this distribution, and is available
       
     6 // at the URL "http://www.eclipse.org/legal/epl-v10.html".
       
     7 //
       
     8 // Initial Contributors:
       
     9 // Nokia Corporation - initial contribution.
       
    10 //
       
    11 // Contributors:
       
    12 //
       
    13 // Description:
       
    14 //
       
    15 
       
    16 #include <e32base.h>
       
    17 #include <stringpool.h>
       
    18 #include <wspdecoder.h>
       
    19 
       
    20 // Constants
       
    21 const TUint8 KWapQuote = 0x7F;
       
    22 const TUint8 KCarryBitMask = 0x80;
       
    23 #define KTopBitMask KCarryBitMask
       
    24 const TUint8 KTop3BitSet = 0x70;
       
    25 const TUint8 KQuoteChar = '\"';
       
    26 
       
    27 // Panic category
       
    28 _LIT(KUriPanicCategory,"WSPDECODER");
       
    29 
       
    30 
       
    31 //***********************************************************************
       
    32 //	TWspHeaderSegmenter
       
    33 //**********************************************************************/
       
    34 
       
    35 
       
    36 /**
       
    37   NextL iterates through the buffer.  Each call returns a TWspField in the paramater.
       
    38 
       
    39   @param aHeader Out - a TWspField containing the header <name,value> pair.  
       
    40   @warning The TWspField::iHdrName will be opened internally.
       
    41 			It must be closed by the caller before this class is destroyed.
       
    42   @return	KErrNone if next field is returned
       
    43 			KErrNotFound at the end of the buffer - no TWspField param returned
       
    44 			KErrCorrupt if segmenting does not parse correctly
       
    45   @leave	RStringPool::OpenFStringL StringPool leave code if opening string fails.
       
    46 */
       
    47 EXPORT_C TInt TWspHeaderSegmenter::NextL(TWspField& aHeader)
       
    48 	{
       
    49 	// have we run out of buffer?
       
    50 	if (iOffset >= iBuffer.Length())
       
    51 		return KErrNotFound;
       
    52 
       
    53 	// Set decoder to current buffer
       
    54 	TWspPrimitiveDecoder decoder(iBuffer.Mid(iOffset));
       
    55 	TInt bufLen = 0;
       
    56 	
       
    57 
       
    58 	// Get the Field Name 
       
    59 	switch(decoder.VarType())
       
    60 		{
       
    61 		case TWspPrimitiveDecoder::EString:
       
    62 			{
       
    63 			TPtrC8 name;
       
    64 			bufLen = decoder.String(name);
       
    65 			if (bufLen < KErrNone) return bufLen;
       
    66 			aHeader.iHdrName = iPool.OpenFStringL(name);
       
    67 			}
       
    68 			break;
       
    69 
       
    70 		case TWspPrimitiveDecoder::E7BitVal:
       
    71 			{
       
    72 			TUint8 name;
       
    73 			bufLen = decoder.Val7Bit(name);
       
    74 			if (bufLen < KErrNone) return bufLen;
       
    75 			
       
    76 			aHeader.iHdrName = iPool.StringF(name, iStringTable);
       
    77 			}
       
    78 			break;
       
    79 
       
    80 		default:	// header name can't be anything else
       
    81 			return KErrCorrupt;
       
    82 		}
       
    83 	
       
    84 	// move our pointer past header name
       
    85 	iOffset += bufLen;
       
    86 
       
    87 	
       
    88 	// Get the value buffer by figuring out the type, then set the pointer to span the entire
       
    89 	// value.  Note - further parsing will happen later to pull out specific value data.
       
    90 	switch(decoder.VarType())
       
    91 		{
       
    92 		case TWspPrimitiveDecoder::ELengthVal:
       
    93 			{
       
    94 			TInt len;
       
    95 			bufLen = decoder.LengthVal(len);
       
    96 			bufLen += len;		
       
    97 			}
       
    98 			break;
       
    99 		case TWspPrimitiveDecoder::EQuotedString:
       
   100 		case TWspPrimitiveDecoder::EString:
       
   101 			{
       
   102 			TPtrC8 strBuf;
       
   103 			bufLen = decoder.String(strBuf);
       
   104 			}
       
   105 			break;
       
   106 		case TWspPrimitiveDecoder::E7BitVal:
       
   107 			bufLen = 1;
       
   108 			break;
       
   109 		default:
       
   110 			return KErrCorrupt;
       
   111 		}
       
   112 	
       
   113 	if (bufLen < 0) 
       
   114 		return bufLen;
       
   115 
       
   116 	if (iOffset + bufLen > iBuffer.Length())
       
   117           return KErrCorrupt;
       
   118 
       
   119 	aHeader.iValBuffer.Set(iBuffer.Mid(iOffset, bufLen));
       
   120 	iOffset += bufLen;
       
   121 	return KErrNone;
       
   122 	}
       
   123 
       
   124 
       
   125  //
       
   126  // WAP-WSP 8.4.1.2
       
   127  //
       
   128 
       
   129 /**
       
   130 	Looks at the byte currently pointed at in this buffer and returns the type.
       
   131 	
       
   132 	@return TWspHeaderType - the type of this data octet
       
   133 */
       
   134 EXPORT_C TWspPrimitiveDecoder::TWspHeaderType TWspPrimitiveDecoder::VarType() const
       
   135 	{
       
   136 	TWspHeaderType type = ENotSet;
       
   137 	
       
   138 	// Check that the offset has not overflowed the buffer
       
   139 	if( iOffset >= iBuffer.Length() )
       
   140 		return type;
       
   141 
       
   142 	TInt octet = iBuffer[iOffset];
       
   143 
       
   144 	if (octet >= 0 && octet <= 31)
       
   145 		type = ELengthVal;
       
   146 	else if (octet == 34)
       
   147 		type = EQuotedString;
       
   148 	else if (octet >= 32 && octet <= 127)
       
   149 		type = EString;
       
   150 	else if (octet >= 128 && octet <= 255)
       
   151 		type = E7BitVal;
       
   152 
       
   153 	return type;
       
   154 	}
       
   155 
       
   156 
       
   157 /**
       
   158 	Returns length of the data following this byte.  
       
   159 	
       
   160 	@pre iBuffer[iOffset] must be valid, VarType() == TWspHeaderType::ELengthVal
       
   161 	@post internal offset gets updated to move past this primitive 
       
   162 	@param aVal Out - the length encoded in this byte that indicates the size of the
       
   163 		  	     data that follows.
       
   164 	@return postive number indicating the number of bytes read from the buffer
       
   165 			KErrCorrupt if data is not formatted correctly.
       
   166 */
       
   167 EXPORT_C TInt TWspPrimitiveDecoder::LengthVal(TInt& aVal)
       
   168 	{
       
   169 	// have we run out of buffer?
       
   170 	if (iOffset >= iBuffer.Length())
       
   171 		return KErrCorrupt;
       
   172 
       
   173 	TInt bufLen = 0;
       
   174 	aVal = iBuffer[iOffset++];
       
   175 
       
   176 	if (aVal == 31)
       
   177 		{
       
   178 		TUint32 uintVarLen = 0;
       
   179 		bufLen = UintVar(uintVarLen);
       
   180 		if (bufLen < KErrNone) return bufLen;
       
   181 		aVal = (TInt)uintVarLen;
       
   182 		}
       
   183 
       
   184 	// add the 1 byte read at to get first aVal
       
   185 	++bufLen;
       
   186 	return bufLen;
       
   187 	}
       
   188 
       
   189 
       
   190 /**
       
   191    Returns a TPtrC holding the string the buffer currently points at without the NULL 
       
   192    termination. If the String type is a quoted string then the quotes are not included 
       
   193    in the returned buffer.
       
   194    
       
   195    @pre iBuffer[iOffset] must be valid, VarType() == TWspType::EString
       
   196    @post internal offset gets updated to move past this primitive 
       
   197    @param aString Out - the string
       
   198    @return postive number indicating the number of bytes read from the buffer
       
   199    		  KErrCorrupt if data is not formatted correctly.
       
   200 */
       
   201 EXPORT_C TInt TWspPrimitiveDecoder::String(TPtrC8& aString)
       
   202 	{
       
   203 	TWspHeaderType type = VarType();
       
   204 	if( type != EString && type != EQuotedString)
       
   205 		return KErrCorrupt;
       
   206 
       
   207 	TInt nullIndex = iBuffer.Mid(iOffset).Locate('\0');
       
   208 	if( nullIndex == KErrNotFound )
       
   209 		return KErrCorrupt;
       
   210 
       
   211 	// Set buffer to data not including the NULL terminator
       
   212 	TPtrC8 buf = iBuffer.Mid(iOffset, nullIndex);
       
   213 
       
   214 	// is there a WAP Quote (0x7F) or a " at the start - step over it
       
   215 	TInt bufferOffset = 0;
       
   216 	const TUint8 firstByte = iBuffer[iOffset];
       
   217 	if( firstByte == KQuoteChar || firstByte == KWapQuote )
       
   218 		++bufferOffset;
       
   219 
       
   220 	// Set the descriptor with the correct buffer segment
       
   221 	aString.Set(buf.Mid(bufferOffset));
       
   222 
       
   223 	// Step over the NULL
       
   224 	++nullIndex;
       
   225 
       
   226 	// update the offset
       
   227 	iOffset += nullIndex;
       
   228 
       
   229 	return nullIndex;
       
   230 	} 
       
   231 
       
   232 /**
       
   233 	Returns a token, a short int or an octet value with the top bit cleared
       
   234 	
       
   235 	@pre iBuffer[iOffset] must be valid, VarType() == TWspHeaderType::E7BitVal
       
   236 	@post internal offset gets updated to move past this primitive 
       
   237 	@param aVal Out - the 7 bit value with top bit cleared
       
   238 	@return postive number indicating the number of bytes read from the buffer
       
   239 		    KErrCorrupt if data is not formatted correctly.
       
   240 */
       
   241 EXPORT_C TInt TWspPrimitiveDecoder::Val7Bit(TUint8& aVal)
       
   242 	{
       
   243 	// have we run out of buffer?
       
   244 	if (iOffset >= iBuffer.Length())
       
   245 		return KErrCorrupt;
       
   246 
       
   247 	aVal = (TUint8)(iBuffer[iOffset] & KWapQuote);
       
   248 	++iOffset;
       
   249 
       
   250 	// 1 byte read
       
   251 	return 1;
       
   252 	}
       
   253 
       
   254 
       
   255 /**
       
   256 	Returns an Integer - could be short or long.
       
   257 	
       
   258 	@pre iBuffer[iOffset] must be valid, VarType() == TWspHeaderType::ELengthVal or
       
   259 		   VarType() == TWspHeaderType::E7BitVal
       
   260 	@post internal offset gets updated to move past this primitive 
       
   261 	@param aVal Out - the long int
       
   262 	@return postive number indicating the number of bytes read from the buffer
       
   263 			  KErrCorrupt if data is not formatted correctly.
       
   264 */
       
   265 EXPORT_C TInt TWspPrimitiveDecoder::Integer(TUint32& aVal)
       
   266 	{
       
   267 	// have we run out of buffer?
       
   268 	if (iOffset >= iBuffer.Length())
       
   269 		return KErrCorrupt;
       
   270 
       
   271 	TInt bufLen = 0;
       
   272 
       
   273 	// read the first byte
       
   274 	aVal = iBuffer[iOffset];
       
   275 	
       
   276 	// short integers have the top bit set
       
   277 	if (aVal & KTopBitMask)
       
   278 		{
       
   279 		aVal &= KWapQuote;
       
   280 		++iOffset;
       
   281 		++bufLen;
       
   282 		}
       
   283 	else
       
   284 		{
       
   285 		bufLen = LongInt(aVal);
       
   286 		}
       
   287 
       
   288 	return bufLen;
       
   289 	}
       
   290 
       
   291 /**
       
   292 	Returns a long int the buffer is currently pointing at. 
       
   293 	
       
   294 	@pre iBuffer[iOffset] must be valid, VarType() == TWspHeaderType::ELengthVal  
       
   295 	@post internal offset gets updated to move past this primitive 
       
   296 	@param aVal Out - the long int
       
   297 	@return postive number indicating the number of bytes read from the buffer
       
   298 		  KErrCorrupt if data is not formatted correctly.
       
   299 */
       
   300 EXPORT_C TInt TWspPrimitiveDecoder::LongInt(TUint32& aVal)
       
   301 	{
       
   302 	// have we run out of buffer?
       
   303 	if (iOffset >= iBuffer.Length())
       
   304 		return KErrCorrupt;
       
   305 
       
   306 	__ASSERT_DEBUG(aVal <= KMaxTUint, User::Panic(KUriPanicCategory, EWspDecoderLongIntOverflow));
       
   307 	// initialize
       
   308 	aVal = 0;
       
   309 
       
   310 	// Get num bytes encoding [len] [byte1] ... [byten]
       
   311 	// we are positioned at that location in the source descriptor
       
   312 	TUint8 numBytes = 0;
       
   313 	TInt bufLen = Val7Bit(numBytes);
       
   314 	if (bufLen < KErrNone) return bufLen;
       
   315 
       
   316 	// len can be up to 30 and verify we have enough buffer
       
   317 	if (numBytes > 30 || numBytes > iBuffer.Mid(iOffset).Length())
       
   318 		return KErrCorrupt;
       
   319 	
       
   320 	// Loop over the buffer, taking each byte and shifting it in count times.  
       
   321 	for (TInt count = 0; count < numBytes ; ++count)
       
   322 		aVal = (aVal << 8) + iBuffer[iOffset++];
       
   323 	
       
   324 	return (bufLen + numBytes);
       
   325 	}
       
   326 
       
   327 /**
       
   328 	Returns a TUint32 
       
   329 	
       
   330 	@pre iBuffer[iOffset] must be valid, VarType() == TWspHeaderType::ELengthVal or
       
   331 		   VarType() == TWspHeaderType::E7BitVal 
       
   332 	@post internal offset gets updated to move past this primitive 
       
   333 	@param aVal Out - the TUint32 decoded 
       
   334 	@return postive number indicating the number of bytes read from the buffer
       
   335 		    KErrCorrupt if data is not formatted correctly.
       
   336 */
       
   337 EXPORT_C TInt TWspPrimitiveDecoder::UintVar(TUint32& aVal)
       
   338 	{
       
   339 	// have we run out of buffer?
       
   340 	if (iOffset >= iBuffer.Length())
       
   341 		return KErrCorrupt;
       
   342 
       
   343 	// initialize return val
       
   344 	aVal = 0;
       
   345 
       
   346 	// maximum length for a uintvar is 5
       
   347 	TInt lenLeft = Min(iBuffer.Mid(iOffset).Length(), 5);
       
   348 
       
   349 	// get the first octet
       
   350 	TUint8 byte = iBuffer[iOffset++];
       
   351 	TInt numBytes = 1;
       
   352 
       
   353 	--lenLeft;	
       
   354 
       
   355 	// Check if any of the top 3 bits, ignoring the very top 'continue' bit, are set.  
       
   356 	// Later if we see that this is a 5 byte number - we'll know it is corrupt.  
       
   357 	// Encoding uses 7 bits/number 7x5=35 and we only support a maxiumum number 
       
   358 	// of 32 bits.
       
   359 	TBool topThreeBitsSet = byte & KTop3BitSet; 
       
   360 	
       
   361 	// copy over data from the byte into our return value (the top bit is a carry bit)
       
   362 	aVal = byte & KWapQuote;
       
   363 
       
   364 	// while the 'continue' bit is set and we have more data
       
   365 	while ((byte & KCarryBitMask) && (lenLeft > 0))
       
   366 		{
       
   367 		// shift our last value up
       
   368 		aVal <<= 7;
       
   369 		// get the next byte
       
   370 		byte = iBuffer[iOffset++];
       
   371 		// copy it over to the lowest byte
       
   372 		aVal |= byte & KWapQuote;
       
   373 		--lenLeft;
       
   374 		++numBytes;
       
   375 		} 
       
   376 
       
   377 	// last octet has continue bit set ... NOT allowed Or
       
   378 	// this was encoded wrong - can't have a number bigger than 32 bits
       
   379 	if ((byte & KCarryBitMask) || (numBytes == 5 && topThreeBitsSet))
       
   380 		return KErrCorrupt;
       
   381 
       
   382 	// number of bytes read
       
   383 	return numBytes;
       
   384 	}
       
   385 
       
   386 
       
   387 /**
       
   388 	Returns a formatted version string 
       
   389 	
       
   390 	@pre iBuffer[iOffset] must be valid, VarType() == TWspHeaderType::ELengthVal  
       
   391 	@post internal offset gets updated to move past this primitive 
       
   392 	@param aPool In - an opened string pool
       
   393 	@param aVer Out - a formatted version string.  Caller must close this string.
       
   394 	@return postive number indicating the number of bytes read from the buffer
       
   395 		    KErrCorrupt if data is not formatted correctly.
       
   396 */
       
   397 EXPORT_C TInt TWspPrimitiveDecoder::VersionL(RStringPool aPool, RStringF& aVer)
       
   398 	{
       
   399 	const TInt KMaxBufLength=5;
       
   400 	TInt bufLen = 0;
       
   401 	TInt byte = iBuffer[iOffset];
       
   402 	if (!(byte & KTopBitMask))
       
   403 		{
       
   404 		TPtrC8 str;
       
   405 		bufLen = String(str);
       
   406 		if (bufLen < KErrNone) return KErrCorrupt;
       
   407 		aVer = aPool.OpenFStringL(str);
       
   408 		}
       
   409 	else
       
   410 		{
       
   411 		// Major 0-7 , Minor 0-15 [xxx][yyyy]
       
   412 		TUint8 val;
       
   413 		bufLen = Val7Bit(val);
       
   414 		if (bufLen < KErrNone) return KErrCorrupt;
       
   415 
       
   416 
       
   417 		TInt minVer =  val & 0x0F;
       
   418 		TInt majVer =  val & 0xF0;
       
   419 		majVer >>= 4;
       
   420 
       
   421 		if (majVer < 0 || majVer > 7)
       
   422 			return KErrCorrupt;
       
   423 
       
   424 		TBuf8<KMaxBufLength> buf;
       
   425 		if (minVer == 0x0F)
       
   426 			{
       
   427 			_LIT8(KVersionFormat, "%D");
       
   428 			buf.Format(KVersionFormat, majVer);
       
   429 			}
       
   430 		else
       
   431 			{
       
   432 			_LIT8(KVersionFormat, "%D.%D");
       
   433 			buf.Format(KVersionFormat, majVer, minVer);
       
   434 			}
       
   435 			aVer = aPool.OpenFStringL(buf);
       
   436 		}
       
   437 
       
   438 	return bufLen;
       
   439 	}
       
   440 
       
   441 /**
       
   442 	Returns a TDateTime offset from January 1, 1970 - WAP WSP Section 8.4.2.3 Panics if 
       
   443 	the time val is greater then the maximum allowable integer size (32 bits).
       
   444 	
       
   445 	@pre iBuffer[iOffset] must be valid, VarType() == TWspHeaderType::ELengthVal  
       
   446 	@post internal offset gets updated to move past this primitive 
       
   447 	@param aDateTime Out - a WAP Date
       
   448 	@return postive number indicating the number of bytes read from the buffer
       
   449 			  KErrCorrupt if data is not formatted correctly.
       
   450 */
       
   451 EXPORT_C TInt TWspPrimitiveDecoder::Date(TDateTime& aDateTime)
       
   452 	{
       
   453 	TUint32 secVal;
       
   454 	TInt bufLen = LongInt(secVal);
       
   455 	__ASSERT_ALWAYS(bufLen <= KMaxTInt, User::Panic(KUriPanicCategory, EWspDecoderDateOverflow));
       
   456 	if (bufLen < KErrNone) return bufLen;
       
   457 
       
   458 	TDateTime dt(1970,EJanuary,0,0,0,0,0);
       
   459 	TTime time(dt);
       
   460 
       
   461 	TInt sec = STATIC_CAST(TInt, secVal);
       
   462 	time += TTimeIntervalSeconds(sec);
       
   463 	aDateTime = time.DateTime();
       
   464 
       
   465 	return bufLen;
       
   466 	}