CMSCompressedDataStreamGenerator.cs :  » PDF » iTextSharp » Org » BouncyCastle » Cms » C# / CSharp Open Source

using System;
using System.IO;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.Cms;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Utilities.IO;
using Org.BouncyCastle.Utilities.Zlib;

namespace Org.BouncyCastle.Cms{
  /**
  * General class for generating a compressed CMS message stream.
  * <p>
  * A simple example of usage.
  * </p>
  * <pre>
  *      CMSCompressedDataStreamGenerator gen = new CMSCompressedDataStreamGenerator();
  *
  *      Stream cOut = gen.Open(outputStream, CMSCompressedDataStreamGenerator.ZLIB);
  *
  *      cOut.Write(data);
  *
  *      cOut.Close();
  * </pre>
  */
  public class CmsCompressedDataStreamGenerator
  {
    public const string ZLib = "1.2.840.113549.1.9.16.3.8";

    private int _bufferSize;
    
    /**
    * base constructor
    */
    public CmsCompressedDataStreamGenerator()
    {
    }

    /**
    * Set the underlying string size for encapsulated data
    *
    * @param bufferSize length of octet strings to buffer the data.
    */
    public void SetBufferSize(
      int bufferSize)
    {
      _bufferSize = bufferSize;
    }

    public Stream Open(
      Stream  outStream,
      string  compressionOID)
    {
      return Open(outStream, CmsObjectIdentifiers.Data.Id, compressionOID);
    }

    public Stream Open(
      Stream  outStream,
      string  contentOID,
      string  compressionOID)
    {
      BerSequenceGenerator sGen = new BerSequenceGenerator(outStream);

      sGen.AddObject(CmsObjectIdentifiers.CompressedData);

      //
      // Compressed Data
      //
      BerSequenceGenerator cGen = new BerSequenceGenerator(
        sGen.GetRawOutputStream(), 0, true);

      // CMSVersion
      cGen.AddObject(new DerInteger(0));

      // CompressionAlgorithmIdentifier
      cGen.AddObject(new AlgorithmIdentifier(new DerObjectIdentifier(ZLib)));

      //
      // Encapsulated ContentInfo
      //
      BerSequenceGenerator eiGen = new BerSequenceGenerator(cGen.GetRawOutputStream());

      eiGen.AddObject(new DerObjectIdentifier(contentOID));

      Stream octetStream = CmsUtilities.CreateBerOctetOutputStream(
        eiGen.GetRawOutputStream(), 0, true, _bufferSize);

      return new CmsCompressedOutputStream(
        new ZDeflaterOutputStream(octetStream), sGen, cGen, eiGen);
    }

    private class CmsCompressedOutputStream
      : BaseOutputStream
    {
      private ZDeflaterOutputStream _out;
      private BerSequenceGenerator _sGen;
      private BerSequenceGenerator _cGen;
      private BerSequenceGenerator _eiGen;

      internal CmsCompressedOutputStream(
        ZDeflaterOutputStream  outStream,
        BerSequenceGenerator  sGen,
        BerSequenceGenerator  cGen,
        BerSequenceGenerator  eiGen)
      {
        _out = outStream;
        _sGen = sGen;
        _cGen = cGen;
        _eiGen = eiGen;
      }

      public override void WriteByte(
        byte b)
      {
        _out.WriteByte(b);
      }

      public override void Write(
        byte[]  bytes,
        int    off,
        int    len)
      {
        _out.Write(bytes, off, len);
      }

      public override void Close()
      {
        _out.Close();
        _eiGen.Close();
        _cGen.Close();
        _sGen.Close();
        base.Close();
      }
    }
  }
}