smtp.java

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/*
 * Copyright 2001-2005 The Apache Software Foundation
 *
 * Licensed 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.commons.net.smtp;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.util.Enumeration;
import java.util.Vector;
import org.apache.commons.net.MalformedServerReplyException;
import org.apache.commons.net.ProtocolCommandListener;
import org.apache.commons.net.ProtocolCommandSupport;
import org.apache.commons.net.SocketClient;

/***
 * SMTP provides the basic the functionality necessary to implement your
 * own SMTP client.  To derive the full benefits of the SMTP class requires
 * some knowledge of the FTP protocol defined in RFC 821.  However, there
 * is no reason why you should have to use the SMTP class.  The
 * {@link org.apache.commons.net.smtp.SMTPClient} class,
 * derived from SMTP,
 * implements all the functionality required of an SMTP client.  The
 * SMTP class is made public to provide access to various SMTP constants
 * and to make it easier for adventurous programmers (or those with
 * special needs) to interact with the SMTP protocol and implement their
 * own clients.  A set of methods with names corresponding to the SMTP
 * command names are provided to facilitate this interaction.
 * <p>
 * You should keep in mind that the SMTP server may choose to prematurely
 * close a connection for various reasons.  The SMTP class will detect a
 * premature SMTP server connection closing when it receives a
 * {@link org.apache.commons.net.smtp.SMTPReply#SERVICE_NOT_AVAILABLE SMTPReply.SERVICE_NOT_AVAILABLE }
 *  response to a command.
 * When that occurs, the SMTP class method encountering that reply will throw
 * an {@link org.apache.commons.net.smtp.SMTPConnectionClosedException}
 * .
 * <code>SMTPConectionClosedException</code>
 * is a subclass of <code> IOException </code> and therefore need not be
 * caught separately, but if you are going to catch it separately, its
 * catch block must appear before the more general <code> IOException </code>
 * catch block.  When you encounter an
 * {@link org.apache.commons.net.smtp.SMTPConnectionClosedException}
 * , you must disconnect the connection with
 * {@link org.apache.commons.net.SocketClient#disconnect  disconnect() }
 * to properly clean up the system resources used by SMTP.  Before
 * disconnecting, you may check the
 * last reply code and text with
 * {@link #getReplyCode  getReplyCode },
 * {@link #getReplyString  getReplyString },
 * and {@link #getReplyStrings  getReplyStrings}.
 * <p>
 * Rather than list it separately for each method, we mention here that
 * every method communicating with the server and throwing an IOException
 * can also throw a
 * {@link org.apache.commons.net.MalformedServerReplyException}
 * , which is a subclass
 * of IOException.  A MalformedServerReplyException will be thrown when
 * the reply received from the server deviates enough from the protocol
 * specification that it cannot be interpreted in a useful manner despite
 * attempts to be as lenient as possible.
 * <p>
 * <p>
 * @author Daniel F. Savarese
 * @see SMTPClient
 * @see SMTPConnectionClosedException
 * @see org.apache.commons.net.MalformedServerReplyException
 ***/

public class SMTP extends SocketClient
{
    /*** The default SMTP port (25). ***/
    public static final int DEFAULT_PORT = 25;

    // We have to ensure that the protocol communication is in ASCII
    // but we use ISO-8859-1 just in case 8-bit characters cross
    // the wire.
    private static final String __DEFAULT_ENCODING = "ISO-8859-1";

    private StringBuffer __commandBuffer;

    BufferedReader _reader;
    BufferedWriter _writer;
    int _replyCode;
    Vector _replyLines;
    boolean _newReplyString;
    String _replyString;

    /***
     * A ProtocolCommandSupport object used to manage the registering of
     * ProtocolCommandListeners and te firing of ProtocolCommandEvents.
     ***/
    protected ProtocolCommandSupport _commandSupport_;

    /***
     * The default SMTP constructor.  Sets the default port to
     * <code>DEFAULT_PORT</code> and initializes internal data structures
     * for saving SMTP reply information.
     ***/
    public SMTP()
    {
        setDefaultPort(DEFAULT_PORT);
        __commandBuffer = new StringBuffer();
        _replyLines = new Vector();
        _newReplyString = false;
        _replyString = null;
        _commandSupport_ = new ProtocolCommandSupport(this);
    }

    private int __sendCommand(String command, String args, boolean includeSpace)
    throws IOException
    {
        String message;

        __commandBuffer.setLength(0);
        __commandBuffer.append(command);

        if (args != null)
        {
            if (includeSpace)
                __commandBuffer.append(' ');
            __commandBuffer.append(args);
        }

        __commandBuffer.append(SocketClient.NETASCII_EOL);

        _writer.write(message = __commandBuffer.toString());
        _writer.flush();

        if (_commandSupport_.getListenerCount() > 0)
            _commandSupport_.fireCommandSent(command, message);

        __getReply();
        return _replyCode;
    }

    private int __sendCommand(int command, String args, boolean includeSpace)
    throws IOException
    {
        return __sendCommand(SMTPCommand._commands[command], args, includeSpace);
    }

    private void __getReply() throws IOException
    {
        int length;

        _newReplyString = true;
        _replyLines.setSize(0);

        String line = _reader.readLine();

        if (line == null)
            throw new SMTPConnectionClosedException(
                "Connection closed without indication.");

        // In case we run into an anomaly we don't want fatal index exceptions
        // to be thrown.
        length = line.length();
        if (length < 3)
            throw new MalformedServerReplyException(
                "Truncated server reply: " + line);

        try
        {
            String code = line.substring(0, 3);
            _replyCode = Integer.parseInt(code);
        }
        catch (NumberFormatException e)
        {
            throw new MalformedServerReplyException(
                "Could not parse response code.\nServer Reply: " + line);
        }

        _replyLines.addElement(line);

        // Get extra lines if message continues.
        if (length > 3 && line.charAt(3) == '-')
        {
            do
            {
                line = _reader.readLine();

                if (line == null)
                    throw new SMTPConnectionClosedException(
                        "Connection closed without indication.");

                _replyLines.addElement(line);

                // The length() check handles problems that could arise from readLine()
                // returning too soon after encountering a naked CR or some other
                // anomaly.
            }
            while (!(line.length() >= 4 && line.charAt(3) != '-' &&
                     Character.isDigit(line.charAt(0))));
            // This is too strong a condition because a non-conforming server
            // could screw things up like ftp.funet.fi does for FTP
            // line.startsWith(code)));
        }

        if (_commandSupport_.getListenerCount() > 0)
            _commandSupport_.fireReplyReceived(_replyCode, getReplyString());

        if (_replyCode == SMTPReply.SERVICE_NOT_AVAILABLE)
            throw new SMTPConnectionClosedException(
                "SMTP response 421 received.  Server closed connection.");
    }

    /*** Initiates control connections and gets initial reply. ***/
    protected void _connectAction_() throws IOException
    {
        super._connectAction_();
        _reader =
            new BufferedReader(new InputStreamReader(_input_,
                                                     __DEFAULT_ENCODING));
        _writer =
            new BufferedWriter(new OutputStreamWriter(_output_,
                                                      __DEFAULT_ENCODING));
        __getReply();
    }


    /***
     * Adds a ProtocolCommandListener.  Delegates this task to
     * {@link #_commandSupport_  _commandSupport_ }.
     * <p>
     * @param listener  The ProtocolCommandListener to add.
     ***/
    public void addProtocolCommandListener(ProtocolCommandListener listener)
    {
        _commandSupport_.addProtocolCommandListener(listener);
    }

    /***
     * Removes a ProtocolCommandListener.  Delegates this task to
     * {@link #_commandSupport_  _commandSupport_ }.
     * <p>
     * @param listener  The ProtocolCommandListener to remove.
     ***/
    public void removeProtocolCommandistener(ProtocolCommandListener listener)
    {
        _commandSupport_.removeProtocolCommandListener(listener);
    }


    /***
     * Closes the connection to the SMTP server and sets to null
     * some internal data so that the memory may be reclaimed by the
     * garbage collector.  The reply text and code information from the
     * last command is voided so that the memory it used may be reclaimed.
     * <p>
     * @exception IOException If an error occurs while disconnecting.
     ***/
    public void disconnect() throws IOException
    {
        super.disconnect();
        _reader = null;
        _writer = null;
        _replyString = null;
        _replyLines.setSize(0);
        _newReplyString = false;
    }


    /***
     * Sends an SMTP command to the server, waits for a reply and returns the
     * numerical response code.  After invocation, for more detailed
     * information, the actual reply text can be accessed by calling
     * {@link #getReplyString  getReplyString } or
     * {@link #getReplyStrings  getReplyStrings }.
     * <p>
     * @param command  The text representation of the  SMTP command to send.
     * @param args The arguments to the SMTP command.  If this parameter is
     *             set to null, then the command is sent with no argument.
     * @return The integer value of the SMTP reply code returned by the server
     *         in response to the command.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending the
     *      command or receiving the server reply.
     ***/
    public int sendCommand(String command, String args) throws IOException
    {
        return __sendCommand(command, args, true);
    }


    /***
     * Sends an SMTP command to the server, waits for a reply and returns the
     * numerical response code.  After invocation, for more detailed
     * information, the actual reply text can be accessed by calling
     * {@link #getReplyString  getReplyString } or
     * {@link #getReplyStrings  getReplyStrings }.
     * <p>
     * @param command  The SMTPCommand constant corresponding to the SMTP command
     *                 to send.
     * @param args The arguments to the SMTP command.  If this parameter is
     *             set to null, then the command is sent with no argument.
     * @return The integer value of the SMTP reply code returned by the server
     *         in response to the command.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending the
     *      command or receiving the server reply.
     ***/
    public int sendCommand(int command, String args) throws IOException
    {
        return sendCommand(SMTPCommand._commands[command], args);
    }


    /***
     * Sends an SMTP command with no arguments to the server, waits for a
     * reply and returns the numerical response code.  After invocation, for
     * more detailed information, the actual reply text can be accessed by
     * calling {@link #getReplyString  getReplyString } or
     * {@link #getReplyStrings  getReplyStrings }.
     * <p>
     * @param command  The text representation of the  SMTP command to send.
     * @return The integer value of the SMTP reply code returned by the server
     *         in response to the command.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending the
     *      command or receiving the server reply.
     ***/
    public int sendCommand(String command) throws IOException
    {
        return sendCommand(command, null);
    }


    /***
     * Sends an SMTP command with no arguments to the server, waits for a
     * reply and returns the numerical response code.  After invocation, for
     * more detailed information, the actual reply text can be accessed by
     * calling {@link #getReplyString  getReplyString } or
     * {@link #getReplyStrings  getReplyStrings }.
     * <p>
     * @param command  The SMTPCommand constant corresponding to the SMTP command
     *                 to send.
     * @return The integer value of the SMTP reply code returned by the server
     *         in response to the command.
     * @exception SMTPConnectionClosedException
     *      If the SMTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send SMTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @exception IOException  If an I/O error occurs while either sending the
     *      command or receiving the server reply.
     ***/
    public int sendCommand(int command) throws IOException
    {
        return sendCommand(command, null);
    }


    /***