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The UnboundID LDAP SDK for Java is a fast, comprehensive, and easy-to-use Java API for communicating with LDAP directory servers and performing related tasks like reading and writing LDIF, encoding and decoding data using base64 and ASN.1 BER, and performing secure communication. This package contains the Commercial Edition of the LDAP SDK, which includes all of the general-purpose functionality contained in the Standard Edition, plus additional functionality specific to UnboundID server products.

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/*
 * Copyright 2008-2017 UnboundID Corp.
 * All Rights Reserved.
 */
/*
 * Copyright (C) 2008-2017 UnboundID Corp.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License (GPLv2 only)
 * or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see .
 */
package com.unboundid.asn1;



import java.io.IOException;
import java.io.OutputStream;
import java.nio.BufferOverflowException;
import java.nio.ByteBuffer;

import com.unboundid.util.ByteStringBuffer;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;

import static com.unboundid.util.Debug.*;



/**
 * This class provides an efficient mechanism for writing ASN.1 elements to
 * output streams.
 */
@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
public final class ASN1Writer
{
  /**
   * The thread-local buffers that will be used for encoding the elements.
   */
  private static final ThreadLocal buffers =
       new ThreadLocal();



  /**
   * The maximum amount of memory that will be used for a thread-local buffer.
   */
  private static final int MAX_BUFFER_LENGTH = 524288;



  /**
   * Prevent this class from being instantiated.
   */
  private ASN1Writer()
  {
    // No implementation is required.
  }



  /**
   * Writes an encoded representation of the provided ASN.1 element to the
   * given output stream.
   *
   * @param  element       The ASN.1 element to be written.
   * @param  outputStream  The output stream to which the encoded representation
   *                       of the element should be written.
   *
   * @throws  IOException  If a problem occurs while writing the element.
   */
  public static void writeElement(final ASN1Element element,
                                  final OutputStream outputStream)
         throws IOException
  {
    debugASN1Write(element);

    ByteStringBuffer buffer = buffers.get();
    if (buffer == null)
    {
      buffer = new ByteStringBuffer();
      buffers.set(buffer);
    }

    element.encodeTo(buffer);

    try
    {
      buffer.write(outputStream);
    }
    finally
    {
      if (buffer.capacity() > MAX_BUFFER_LENGTH)
      {
        buffer.setCapacity(MAX_BUFFER_LENGTH);
      }
      buffer.clear();
    }
  }



  /**
   * Appends an encoded representation of the provided ASN.1 element to the
   * given byte buffer.  When this method completes, the position will be at the
   * beginning of the written element, and the limit will be at the end.
   *
   * @param  element  The ASN.1 element to be written.
   * @param  buffer   The buffer to which the element should be added.
   *
   * @throws  BufferOverflowException  If the provided buffer does not have
   *                                   enough space between the position and
   *                                   the limit to hold the encoded element.
   */
  public static void writeElement(final ASN1Element element,
                                  final ByteBuffer buffer)
         throws BufferOverflowException
  {
    debugASN1Write(element);

    ByteStringBuffer b = buffers.get();
    if (b == null)
    {
      b = new ByteStringBuffer();
      buffers.set(b);
    }

    element.encodeTo(b);

    try
    {
      if (buffer.remaining() < b.length())
      {
        throw new BufferOverflowException();
      }

      final int pos = buffer.position();
      buffer.put(b.getBackingArray(), 0, b.length());
      buffer.limit(buffer.position());
      buffer.position(pos);
    }
    finally
    {
      if (b.capacity() > MAX_BUFFER_LENGTH)
      {
        b.setCapacity(MAX_BUFFER_LENGTH);
      }
      b.clear();
    }
  }
}