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//
// System.Web.Mail.ToUUEncodingTransform.cs
//
// Author(s):
// Per Arneng <pt99par@student.bth.se>
//
//
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
using System;
using System.Security.Cryptography;
namespace System.Web.Mail {
// This class transforms blocks of plaintext to UU encoding
internal class ToUUEncodingTransform : ICryptoTransform {
public int InputBlockSize { get { return 45; } }
public int OutputBlockSize { get { return 61; } }
public bool CanTransformMultipleBlocks { get { return true; } }
public bool CanReuseTransform { get { return true; } }
// transforms a block of bytes to UU encoding
public int TransformBlock( byte[] inputBuffer,
int inputOffset,
int inputCount,
byte[] outputBuffer,
int outputOffset
) {
// write the line length length+0x20
outputBuffer[ 0 ] = (byte)'M';
// transform the block 3bytes at a time
for( int i=0;i<15;i++ ) {
TransformTriplet( inputBuffer , inputOffset + i * 3 , 3,
outputBuffer , outputOffset + i * 4 + 1);
}
return OutputBlockSize;
}
// make a final uu transformations
public byte[] TransformFinalBlock(byte[] inputBuffer,
int inputOffset,
int inputCount
) {
// calculate how many 4-byte blocks there are
int tripletBlocks = inputCount / 3 + 1;
// create a new buffer and copy the input data into that
byte[] buffer = new byte[ tripletBlocks * 3 ];
Buffer.BlockCopy( inputBuffer,inputOffset, buffer,0,inputCount);
// create the outpur buffer and set the first byte
// to the length+0x20
byte[] outputBuffer = new byte[ tripletBlocks * 4 + 1 ];
outputBuffer[ 0 ] = (byte)(inputCount+0x20);
// transform the block 3bytes at a time
for( int i =0 ; i < tripletBlocks ; i++ ) {
TransformTriplet( inputBuffer , inputOffset + i * 3 , 3,
outputBuffer , i * 4 + 1);
}
return outputBuffer;
}
// transforms a 3byte buffer to a 4byte uuencoded buffer
protected int TransformTriplet( byte[] inputBuffer,
int inputOffset,
int inputCount,
byte[] outputBuffer,
int outputOffset
) {
byte a = inputBuffer[ inputOffset + 0 ];
byte b = inputBuffer[ inputOffset + 1 ];
byte c = inputBuffer[ inputOffset + 2 ];
outputBuffer[ outputOffset + 0 ] =
(byte)(0x20 + (( a >> 2 ) & 0x3F));
outputBuffer[ outputOffset + 1 ] =
(byte)(0x20 + (((a << 4) | ((b >> 4) & 0xF)) & 0x3F));
outputBuffer[ outputOffset + 2 ] =
(byte)(0x20 + (((b << 2) | ((c >> 6) & 0x3)) & 0x3F));
outputBuffer[ outputOffset + 3 ] =
(byte)(0x20 + (( c ) & 0x3F));
// tanslate all 0x20 to 0x60 according to specs
for( int i = 0; i < 4; i++ ) {
if( outputBuffer[ outputOffset + i ] == 0x20 ) {
outputBuffer[ outputOffset + i ] = 0x60;
}
}
return 4;
}
public void Dispose() {}
}
}
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