trunk/ldap/codec/core/src/main/java/org/apache/directory/api/ldap/codec/api/LdapDecoder.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 *
 */
package org.apache.directory.api.ldap.codec.api;


import java.io.InputStream;
import java.nio.ByteBuffer;

import org.apache.directory.api.asn1.DecoderException;
import org.apache.directory.api.asn1.ber.Asn1Decoder;
import org.apache.directory.api.asn1.ber.tlv.TLVStateEnum;
import org.apache.directory.api.i18n.I18n;
import org.apache.directory.api.ldap.model.message.Message;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * The LdapDecoder decodes ASN.1 BER encoded PDUs into LDAP messages
 *
 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
 */
public class LdapDecoder
{
    /** The logger */
    private static final Logger LOG = LoggerFactory.getLogger( LdapDecoder.class );

    /** A speedup for logger */
    private static final boolean IS_DEBUG = LOG.isDebugEnabled();

    /** The ASN 1 decoder instance */
    private Asn1Decoder asn1Decoder;

    /** The name of the LdapSession's attribute for the LDAP container used during the decoding */
    public static final String MESSAGE_CONTAINER_ATTR = "LDAP-container";

    /** The maximum PDU size, stored into the LDAPSession's attribute */
    public static final String MAX_PDU_SIZE_ATTR = "LDAP-maxPduSize";


    /**
     * Creates an instance of a Ldap Decoder implementation.
     */
    public LdapDecoder()
    {
        asn1Decoder = new Asn1Decoder();
    }


    /**
     * Decodes a PDU from an input stream into a Ldap message container. We can only
     * decode one complete message.
     *
     * @param in The input stream to read and decode PDU bytes from
     * @return return The decoded message
     */
    public Message decode( InputStream in, LdapMessageContainer<MessageDecorator<? extends Message>> container )
        throws DecoderException
    {
        try
        {
            int amount;

            while ( in.available() > 0 )
            {
                byte[] buf = new byte[in.available()];

                amount = in.read( buf );
                if ( amount == -1 )
                {
                    break;
                }

                asn1Decoder.decode( ByteBuffer.wrap( buf, 0, amount ), container );
            }
        }
        catch ( Exception e )
        {
            String message = I18n.err( I18n.ERR_04060, e.getLocalizedMessage() );
            LOG.error( message );
            throw new DecoderException( message, e );
        }

        if ( container.getState() == TLVStateEnum.PDU_DECODED )
        {
            if ( IS_DEBUG )
            {
                LOG.debug( "Decoded LdapMessage : " + container );
            }

            return container.getMessage();
        }
        else
        {
            LOG.error( I18n.err( I18n.ERR_04062 ) );
            throw new DecoderException( I18n.err( I18n.ERR_04063 ) );
        }
    }

    /**
     * Decode an incoming buffer into LDAP messages. The result can be 0, 1 or many
     * LDAP messages, which will be stored into the array the caller has created.
     * 
     * @param buffer The incoming byte buffer
     * @param messageContainer The LdapMessageContainer which will be used to store the
     * message being decoded. If the message is not fully decoded, the ucrrent state
     * is stored into this container
     * @param decodedMessages The list of decoded messages
     * @throws Exception If the decoding failed
     *
    public void decode( ByteBuffer buffer, LdapMessageContainer<MessageDecorator<? extends Message>> messageContainer, List<Message> decodedMessages ) throws DecoderException
    {
        buffer.mark();

        while ( buffer.hasRemaining() )
        {
            try
            {
                if ( IS_DEBUG )
                {
                    LOG.debug( "Decoding the PDU : " );

                    int size = buffer.limit();
                    int position = buffer.position();
                    int pduLength = size - position;

                    byte[] array = new byte[pduLength];

                    System.arraycopy(buffer.array(), position, array, 0, pduLength);

                    buffer.position( size );

                    if ( array.length == 0 )
                    {
                        LOG.debug( "NULL buffer, what the HELL ???" );
                    }
                    else
                    {
                        LOG.debug( Strings.dumpBytes(array) );
                    }

                    buffer.reset();
                }

                asn1Decoder.decode( buffer, messageContainer );

                if ( messageContainer.getState() == TLVStateEnum.PDU_DECODED )
                {
                    if ( IS_DEBUG )
                    {
                        LOG.debug( "Decoded LdapMessage : " + messageContainer.getMessage() );
                    }

                    Message message = messageContainer.getMessage();

                    decodedMessages.add( message );

                    messageContainer.clean();
                }
            }
            catch ( DecoderException de )
            {
                buffer.clear();
                messageContainer.clean();

                if ( de instanceof ResponseCarryingException )
                {
                    // Transform the DecoderException message to a MessageException
                    ResponseCarryingMessageException rcme = new ResponseCarryingMessageException( de.getMessage() );
                    rcme.setResponse( ( ( ResponseCarryingException ) de ).getResponse() );

                    throw rcme;
                }
                else
                {
                    // TODO : This is certainly not the way we should handle such an exception !
                    throw new ResponseCarryingException( de.getMessage() );
                }
            }
        }
    }*/
}