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/// <summary>
/// This stream performs in-place decoding of quoted-printable
/// encoded streams used in headers. Encoding requires copying into a separate
/// buffer as the data being encoded will most likely grow.
/// Encoding and decoding is done transparently to the caller.
/// this class is meant to be used when RFC 2047 quoted stream encoding
///is needed. This is for headers such as subject and should NOT be
///used for email body
/// </summary>
//-----------------------------------------------------------------------------
// <copyright file="HeaderQuotedPrintableStream.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//-----------------------------------------------------------------------------
namespace System.Net.Mime
{
using System;
using System.IO;
using System.Text;
/// <summary>
/// This stream performs in-place decoding of quoted-printable
/// encoded streams. Encoding requires copying into a separate
/// buffer as the data being encoded will most likely grow.
/// Encoding and decoding is done transparently to the caller.
/// </summary>
internal class QEncodedStream : DelegatedStream, IEncodableStream
{
//folding takes up 3 characters "\r\n "
const int sizeOfFoldingCRLF = 3;
static byte[] hexDecodeMap = new byte[] {// 0 1 2 3 4 5 6 7 8 9 A B C D E F
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // 0
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // 1
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // 2
0, 1, 2, 3, 4, 5, 6, 7, 8, 9,255,255,255,255,255,255, // 3
255, 10, 11, 12, 13, 14, 15,255,255,255,255,255,255,255,255,255, // 4
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // 5
255, 10, 11, 12, 13, 14, 15,255,255,255,255,255,255,255,255,255, // 6
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // 7
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // 8
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // 9
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // A
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // B
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // C
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // D
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // E
255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255, // F
};
//bytes that correspond to the hex char representations in ASCII (0-9, A-F)
static byte[] hexEncodeMap = new byte[] { 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 65, 66, 67, 68, 69, 70 };
ReadStateInfo readState;
WriteStateInfoBase writeState;
internal QEncodedStream(WriteStateInfoBase wsi)
{
this.writeState = wsi;
}
ReadStateInfo ReadState
{
get
{
if (this.readState == null)
this.readState = new ReadStateInfo();
return this.readState;
}
}
internal WriteStateInfoBase WriteState
{
get
{
return this.writeState;
}
}
public override IAsyncResult BeginWrite(byte[] buffer, int offset, int count, AsyncCallback callback, object state)
{
if (buffer == null)
throw new ArgumentNullException("buffer");
if (offset < 0 || offset > buffer.Length)
throw new ArgumentOutOfRangeException("offset");
if (offset + count > buffer.Length)
throw new ArgumentOutOfRangeException("count");
WriteAsyncResult result = new WriteAsyncResult(this, buffer, offset, count, callback, state);
result.Write();
return result;
}
public override void Close()
{
FlushInternal();
base.Close();
}
public int DecodeBytes(byte[] buffer, int offset, int count)
{
unsafe
{
fixed (byte* pBuffer = buffer)
{
byte* start = pBuffer + offset;
byte* source = start;
byte* dest = start;
byte* end = start + count;
// if the last read ended in a partially decoded
// sequence, pick up where we left off.
if (ReadState.IsEscaped)
{
// this will be -1 if the previous read ended
// with an escape character.
if (ReadState.Byte == -1)
{
// if we only read one byte from the underlying
// stream, we'll need to save the byte and
// ask for more.
if (count == 1)
{
ReadState.Byte = *source;
return 0;
}
// '=\r\n' means a soft (aka. invisible) CRLF sequence...
if (source[0] != '\r' || source[1] != '\n')
{
byte b1 = hexDecodeMap[source[0]];
byte b2 = hexDecodeMap[source[1]];
if (b1 == 255)
throw new FormatException(SR.GetString(SR.InvalidHexDigit, b1));
if (b2 == 255)
throw new FormatException(SR.GetString(SR.InvalidHexDigit, b2));
*dest++ = (byte)((b1 << 4) + b2);
}
source += 2;
}
else
{
// '=\r\n' means a soft (aka. invisible) CRLF sequence...
if (ReadState.Byte != '\r' || *source != '\n')
{
byte b1 = hexDecodeMap[ReadState.Byte];
byte b2 = hexDecodeMap[*source];
if (b1 == 255)
throw new FormatException(SR.GetString(SR.InvalidHexDigit, b1));
if (b2 == 255)
throw new FormatException(SR.GetString(SR.InvalidHexDigit, b2));
*dest++ = (byte)((b1 << 4) + b2);
}
source++;
}
// reset state for next read.
ReadState.IsEscaped = false;
ReadState.Byte = -1;
}
// Here's where most of the decoding takes place.
// We'll loop around until we've inspected all the
// bytes read.
while (source < end)
{
// if the source is not an escape character, then
// just copy as-is.
if (*source != '=')
{
if (*source == '_')
{
*dest++ = (byte)' ';
source++;
}
else
{
*dest++ = *source++;
}
}
else
{
// determine where we are relative to the end
// of the data. If we don't have enough data to
// decode the escape sequence, save off what we
// have and continue the decoding in the next
// read. Otherwise, decode the data and copy
// into dest.
switch (end - source)
{
case 2:
ReadState.Byte = source[1];
goto case 1;
case 1:
ReadState.IsEscaped = true;
goto EndWhile;
default:
if (source[1] != '\r' || source[2] != '\n')
{
byte b1 = hexDecodeMap[source[1]];
byte b2 = hexDecodeMap[source[2]];
if (b1 == 255)
throw new FormatException(SR.GetString(SR.InvalidHexDigit, b1));
if (b2 == 255)
throw new FormatException(SR.GetString(SR.InvalidHexDigit, b2));
*dest++ = (byte)((b1 << 4) + b2);
}
source += 3;
break;
}
}
}
EndWhile:
count = (int)(dest - start);
}
}
return count;
}
public int EncodeBytes(byte[] buffer, int offset, int count)
{
// Add Encoding header, if any. e.g. =?encoding?b?
writeState.AppendHeader();
// Scan one character at a time looking for chars that need to be encoded.
int cur = offset;
for (; cur < count + offset; cur++)
{
if ( // Fold if we're before a whitespace and encoding another character would be too long
((WriteState.CurrentLineLength + sizeOfFoldingCRLF + WriteState.FooterLength >= WriteState.MaxLineLength)
&& (buffer[cur] == ' ' || buffer[cur] == '\t' || buffer[cur] == '\r' || buffer[cur] == '\n'))
// Or just adding the footer would be too long.
|| (WriteState.CurrentLineLength + writeState.FooterLength >= WriteState.MaxLineLength)
)
{
WriteState.AppendCRLF(true);
}
// We don't need to worry about RFC 2821 4.5.2 (encoding first dot on a line),
// it is done by the underlying 7BitStream
//always encode CRLF
if (buffer[cur] == '\r' && cur + 1 < count + offset && buffer[cur + 1] == '\n')
{
cur++;
//the encoding for CRLF is =0D=0A
WriteState.Append((byte)'=', (byte)'0', (byte)'D', (byte)'=', (byte)'0', (byte)'A');
}
else if (buffer[cur] == ' ')
{
//spaces should be escaped as either '_' or '=20' and
//we have chosen '_' for parity with other email client
//behavior
WriteState.Append((byte)'_');
}
// RFC 2047 Section 5 part 3 also allows for !*+-/ but these arn't required in headers.
// Conservatively encode anything but letters or digits.
else if (Uri.IsAsciiLetterOrDigit((char)buffer[cur]))
{
// Just a regular printable ascii char.
WriteState.Append(buffer[cur]);
}
else
{
//append an = to indicate an encoded character
WriteState.Append((byte)'=');
//shift 4 to get the first four bytes only and look up the hex digit
WriteState.Append(hexEncodeMap[buffer[cur] >> 4]);
//clear the first four bytes to get the last four and look up the hex digit
WriteState.Append(hexEncodeMap[buffer[cur] & 0xF]);
}
}
WriteState.AppendFooter();
return cur - offset;
}
public Stream GetStream()
{
return this;
}
public string GetEncodedString()
{
return ASCIIEncoding.ASCII.GetString(this.WriteState.Buffer, 0, this.WriteState.Length);
}
public override void EndWrite(IAsyncResult asyncResult)
{
WriteAsyncResult.End(asyncResult);
}
public override void Flush()
{
FlushInternal();
base.Flush();
}
void FlushInternal()
{
if (this.writeState != null && this.writeState.Length > 0)
{
base.Write(WriteState.Buffer, 0, WriteState.Length);
WriteState.Reset();
}
}
public override void Write(byte[] buffer, int offset, int count)
{
if (buffer == null)
throw new ArgumentNullException("buffer");
if (offset < 0 || offset > buffer.Length)
throw new ArgumentOutOfRangeException("offset");
if (offset + count > buffer.Length)
throw new ArgumentOutOfRangeException("count");
int written = 0;
for (; ; )
{
written += EncodeBytes(buffer, offset + written, count - written);
if (written < count)
FlushInternal();
else
break;
}
}
class ReadStateInfo
{
bool isEscaped = false;
short b1 = -1;
internal bool IsEscaped
{
get { return this.isEscaped; }
set { this.isEscaped = value; }
}
internal short Byte
{
get { return this.b1; }
set { this.b1 = value; }
}
}
class WriteAsyncResult : LazyAsyncResult
{
QEncodedStream parent;
byte[] buffer;
int offset;
int count;
static AsyncCallback onWrite = new AsyncCallback(OnWrite);
int written;
internal WriteAsyncResult(QEncodedStream parent, byte[] buffer, int offset, int count, AsyncCallback callback, object state)
: base(null, state, callback)
{
this.parent = parent;
this.buffer = buffer;
this.offset = offset;
this.count = count;
}
void CompleteWrite(IAsyncResult result)
{
this.parent.BaseStream.EndWrite(result);
this.parent.WriteState.Reset();
}
internal static void End(IAsyncResult result)
{
WriteAsyncResult thisPtr = (WriteAsyncResult)result;
thisPtr.InternalWaitForCompletion();
System.Diagnostics.Debug.Assert(thisPtr.written == thisPtr.count);
}
static void OnWrite(IAsyncResult result)
{
if (!result.CompletedSynchronously)
{
WriteAsyncResult thisPtr = (WriteAsyncResult)result.AsyncState;
try
{
thisPtr.CompleteWrite(result);
thisPtr.Write();
}
catch (Exception e)
{
thisPtr.InvokeCallback(e);
}
}
}
internal void Write()
{
for (; ; )
{
this.written += this.parent.EncodeBytes(this.buffer, this.offset + this.written, this.count - this.written);
if (this.written < this.count)
{
IAsyncResult result = this.parent.BaseStream.BeginWrite(this.parent.WriteState.Buffer, 0, this.parent.WriteState.Length, onWrite, this);
if (!result.CompletedSynchronously)
break;
CompleteWrite(result);
}
else
{
InvokeCallback();
break;
}
}
}
}
}
}
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