EncodedStreamFactory.cs source code in C# .NET

Source code for the .NET framework in C#



/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Net / System / Net / Mail / EncodedStreamFactory.cs / 1305376 / EncodedStreamFactory.cs

                            namespace System.Net.Mime 
    using System;
    using System.IO;
    using System.Text; 

    internal class EncodedStreamFactory 
        //RFC 2822: no encoded-word line should be longer than 76 characters not including the soft CRLF
        //since the header length is unknown (if there even is one) we're going to be slightly more conservative 
        //and cut off at 70.  This will also prevent any other folding behavior from being triggered anywhere
        //in the code
        private const int defaultMaxLineLength = 70;
        //default buffer size for encoder
        private const int initialBufferSize = 1024; 
        internal static int DefaultMaxLineLength
                return defaultMaxLineLength;
        //get a raw encoder, not for use with header encoding 
        internal IEncodableStream GetEncoder(TransferEncoding encoding, Stream stream)
            //raw encoder
            if (encoding == TransferEncoding.Base64)
                return new Base64Stream(stream, new Base64WriteStateInfo(initialBufferSize, new byte[0], new byte[0], DefaultMaxLineLength));
            //return a QuotedPrintable stream because this is not being used for header encoding
            if (encoding == TransferEncoding.QuotedPrintable) 
                return new QuotedPrintableStream(stream, true); 

            if (encoding == TransferEncoding.SevenBit) 
                return new SevenBitStream(stream);

            throw new NotSupportedException("Encoding Stream");

        //use for encoding headers 
        internal IEncodableStream GetEncoderForHeader(Encoding encoding, bool useBase64Encoding, int headerTextLength) 
            WriteStateInfoBase writeState; 
            byte[] header = CreateHeader(encoding, useBase64Encoding);
            byte[] footer = CreateFooter();

            if (useBase64Encoding) 
                writeState = new Base64WriteStateInfo(initialBufferSize, header, footer, DefaultMaxLineLength); 
                writeState.MimeHeaderLength = headerTextLength; 
                return new Base64Stream((Base64WriteStateInfo)writeState);

            writeState = new QuotedStringWriteStateInfo(initialBufferSize, header, footer, DefaultMaxLineLength);
            writeState.MimeHeaderLength = headerTextLength;
            return new QEncodedStream((QuotedStringWriteStateInfo)writeState);
        //Create the header for what type of byte encoding is going to be used
        //based on the encoding type and if base64 encoding should be forced 
        //sample header: =?utf-8?B?
        protected byte[] CreateHeader(Encoding encoding, bool useBase64Encoding)
            //create encoded work header 
            string header = String.Format("=?{0}?{1}?", encoding.HeaderName, useBase64Encoding ? "B" : "Q");
            return Encoding.ASCII.GetBytes(header); 

        //creates the footer that marks the end of a quoted string of some sort 
        protected byte[] CreateFooter()
            byte[] footer = {(byte)'?', (byte)'='};
            return footer; 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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