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