MqttInputStream.java

/* 
 * Copyright (c) 2009, 2012 IBM Corp.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *    Dave Locke - initial API and implementation and/or initial documentation
 */
package org.eclipse.paho.client.mqttv3.internal.wire;

import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.internal.ExceptionHelper;
import org.eclipse.paho.client.mqttv3.logging.Logger;
import org.eclipse.paho.client.mqttv3.logging.LoggerFactory;


/**
 * An <code>MqttInputStream</code> lets applications read instances of
 * <code>MqttWireMessage</code>. 
 */
public class MqttInputStream extends InputStream {
	private static final String className = MqttInputStream.class.getName();
	private DataInputStream in;
	Logger log = LoggerFactory.getLogger(LoggerFactory.MQTT_CLIENT_MSG_CAT, className);

	public MqttInputStream(InputStream in) {
		this.in = new DataInputStream(in);
	}
	
	public int read() throws IOException {
		return in.read();
	}
	
	public int available() throws IOException {
		return in.available();
	}
	
	public void close() throws IOException {
		in.close();
	}
	
	/**
	 * Reads an <code>MqttWireMessage</code> from the stream.
	 */
	public MqttWireMessage readMqttWireMessage() throws IOException, MqttException {
		final String methodName ="readMqttWireMessage";
		ByteArrayOutputStream bais = new ByteArrayOutputStream();
		byte first = in.readByte();
		byte type = (byte) ((first >>> 4) & 0x0F);
		if ((type < MqttWireMessage.MESSAGE_TYPE_CONNECT) ||
			(type > MqttWireMessage.MESSAGE_TYPE_DISCONNECT)) {
			// Invalid MQTT message type...
			throw ExceptionHelper.createMqttException(MqttException.REASON_CODE_INVALID_MESSAGE);
		}
		long remLen = MqttWireMessage.readMBI(in).getValue();
		bais.write(first);
		// bit silly, we decode it then encode it
		bais.write(MqttWireMessage.encodeMBI(remLen));
		byte[] packet = new byte[(int)(bais.size()+remLen)];
		in.readFully(packet,bais.size(),packet.length - bais.size());
		byte[] header = bais.toByteArray();
		System.arraycopy(header,0,packet,0, header.length);
		MqttWireMessage message = MqttWireMessage.createWireMessage(packet);
		// @TRACE 501= received {0} 
		log.fine(className, methodName, "501",new Object[] {message});
		return message;
	}
}