commons-net.jar Source Code

commons-net.jar is the bytecode of Apache Commons Net library, which implements the client side of many basic Internet protocols.

Apache Commons Net Source Code files are provided in the binary packge (commons-net-3.8.0-bin.zip). You can download it at Apache Commons Net Website.

The source code of commons-net-3.8.0.jar is provided below:

✍: FYIcenter

org/apache/commons/net/ftp/FTPClient.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.commons.net.ftp;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Locale;
import java.util.Properties;
import java.util.Random;
import java.util.Set;
import java.util.regex.Matcher;

import org.apache.commons.net.MalformedServerReplyException;
import org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory;
import org.apache.commons.net.ftp.parser.FTPFileEntryParserFactory;
import org.apache.commons.net.ftp.parser.MLSxEntryParser;
import org.apache.commons.net.io.CRLFLineReader;
import org.apache.commons.net.io.CopyStreamAdapter;
import org.apache.commons.net.io.CopyStreamEvent;
import org.apache.commons.net.io.CopyStreamListener;
import org.apache.commons.net.io.FromNetASCIIInputStream;
import org.apache.commons.net.io.SocketOutputStream;
import org.apache.commons.net.io.ToNetASCIIOutputStream;
import org.apache.commons.net.io.Util;
import org.apache.commons.net.util.NetConstants;

/**
 * FTPClient encapsulates all the functionality necessary to store and
 * retrieve files from an FTP server.  This class takes care of all
 * low level details of interacting with an FTP server and provides
 * a convenient higher level interface.  As with all classes derived
 * from {@link org.apache.commons.net.SocketClient},
 * you must first connect to the server with
 * {@link org.apache.commons.net.SocketClient#connect  connect }
 * before doing anything, and finally
 * {@link org.apache.commons.net.SocketClient#disconnect  disconnect }
 * after you're completely finished interacting with the server.
 * Then you need to check the FTP reply code to see if the connection
 * was successful.  For example:
 * <pre>
 *    FTPClient ftp = new FTPClient();
 *    FTPClientConfig config = new FTPClientConfig();
 *    config.setXXX(YYY); // change required options
 *    // for example config.setServerTimeZoneId("Pacific/Pitcairn")
 *    ftp.configure(config );
 *    boolean error = false;
 *    try {
 *      int reply;
 *      String server = "ftp.example.com";
 *      ftp.connect(server);
 *      System.out.println("Connected to " + server + ".");
 *      System.out.print(ftp.getReplyString());
 *
 *      // After connection attempt, you should check the reply code to verify
 *      // success.
 *      reply = ftp.getReplyCode();
 *
 *      if(!FTPReply.isPositiveCompletion(reply)) {
 *        ftp.disconnect();
 *        System.err.println("FTP server refused connection.");
 *        System.exit(1);
 *      }
 *      ... // transfer files
 *      ftp.logout();
 *    } catch(IOException e) {
 *      error = true;
 *      e.printStackTrace();
 *    } finally {
 *      if(ftp.isConnected()) {
 *        try {
 *          ftp.disconnect();
 *        } catch(IOException ioe) {
 *          // do nothing
 *        }
 *      }
 *      System.exit(error ? 1 : 0);
 *    }
 * </pre>
 * <p>
 * Immediately after connecting is the only real time you need to check the
 * reply code (because connect is of type void).  The convention for all the
 * FTP command methods in FTPClient is such that they either return a
 * boolean value or some other value.
 * The boolean methods return true on a successful completion reply from
 * the FTP server and false on a reply resulting in an error condition or
 * failure.  The methods returning a value other than boolean return a value
 * containing the higher level data produced by the FTP command, or null if a
 * reply resulted in an error condition or failure.  If you want to access
 * the exact FTP reply code causing a success or failure, you must call
 * {@link org.apache.commons.net.ftp.FTP#getReplyCode  getReplyCode } after
 * a success or failure.
 * <p>
 * The default settings for FTPClient are for it to use
 * <code> FTP.ASCII_FILE_TYPE </code>,
 * <code> FTP.NON_PRINT_TEXT_FORMAT </code>,
 * <code> FTP.STREAM_TRANSFER_MODE </code>, and
 * <code> FTP.FILE_STRUCTURE </code>.  The only file types directly supported
 * are <code> FTP.ASCII_FILE_TYPE </code> and
 * <code> FTP.BINARY_FILE_TYPE </code>.  Because there are at least 4
 * different EBCDIC encodings, we have opted not to provide direct support
 * for EBCDIC.  To transfer EBCDIC and other unsupported file types you
 * must create your own filter InputStreams and OutputStreams and wrap
 * them around the streams returned or required by the FTPClient methods.
 * FTPClient uses the {@link ToNetASCIIOutputStream NetASCII}
 * filter streams to provide transparent handling of ASCII files.  We will
 * consider incorporating EBCDIC support if there is enough demand.
 * <p>
 * <code> FTP.NON_PRINT_TEXT_FORMAT </code>,
 * <code> FTP.STREAM_TRANSFER_MODE </code>, and
 * <code> FTP.FILE_STRUCTURE </code> are the only supported formats,
 * transfer modes, and file structures.
 * <p>
 * Because the handling of sockets on different platforms can differ
 * significantly, the FTPClient automatically issues a new PORT (or EPRT) command
 * prior to every transfer requiring that the server connect to the client's
 * data port.  This ensures identical problem-free behavior on Windows, Unix,
 * and Macintosh platforms.  Additionally, it relieves programmers from
 * having to issue the PORT (or EPRT) command themselves and dealing with platform
 * dependent issues.
 * <p>
 * Additionally, for security purposes, all data connections to the
 * client are verified to ensure that they originated from the intended
 * party (host and port).  If a data connection is initiated by an unexpected
 * party, the command will close the socket and throw an IOException.  You
 * may disable this behavior with
 * {@link #setRemoteVerificationEnabled setRemoteVerificationEnabled()}.
 * <p>
 * You should keep in mind that the FTP server may choose to prematurely
 * close a connection if the client has been idle for longer than a
 * given time period (usually 900 seconds).  The FTPClient class will detect a
 * premature FTP server connection closing when it receives a
 * {@link org.apache.commons.net.ftp.FTPReply#SERVICE_NOT_AVAILABLE FTPReply.SERVICE_NOT_AVAILABLE }
 *  response to a command.
 * When that occurs, the FTP class method encountering that reply will throw
 * an {@link org.apache.commons.net.ftp.FTPConnectionClosedException}
 * .
 * <code>FTPConnectionClosedException</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.ftp.FTPConnectionClosedException}
 * , you must disconnect the connection with
 * {@link #disconnect  disconnect() } to properly clean up the
 * system resources used by FTPClient.  Before disconnecting, you may check the
 * last reply code and text with
 * {@link org.apache.commons.net.ftp.FTP#getReplyCode  getReplyCode },
 * {@link org.apache.commons.net.ftp.FTP#getReplyString  getReplyString },
 * and
 * {@link org.apache.commons.net.ftp.FTP#getReplyStrings  getReplyStrings}.
 * You may avoid server disconnections while the client is idle by
 * periodically sending NOOP commands to the server.
 * <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>
 * Listing API Examples
 * Both paged and unpaged examples of directory listings are available,
 * as follows:
 * <p>
 * Unpaged (whole list) access, using a parser accessible by auto-detect:
 * <pre>
 *    FTPClient f = new FTPClient();
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPFile[] files = f.listFiles(directory);
 * </pre>
 * <p>
 * Paged access, using a parser not accessible by auto-detect.  The class
 * defined in the first parameter of initateListParsing should be derived
 * from org.apache.commons.net.FTPFileEntryParser:
 * <pre>
 *    FTPClient f = new FTPClient();
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPListParseEngine engine =
 *       f.initiateListParsing("com.whatever.YourOwnParser", directory);
 *
 *    while (engine.hasNext()) {
 *       FTPFile[] files = engine.getNext(25);  // "page size" you want
 *       //do whatever you want with these files, display them, etc.
 *       //expensive FTPFile objects not created until needed.
 *    }
 * </pre>
 * <p>
 * Paged access, using a parser accessible by auto-detect:
 * <pre>
 *    FTPClient f = new FTPClient();
 *    f.connect(server);
 *    f.login(username, password);
 *    FTPListParseEngine engine = f.initiateListParsing(directory);
 *
 *    while (engine.hasNext()) {
 *       FTPFile[] files = engine.getNext(25);  // "page size" you want
 *       //do whatever you want with these files, display them, etc.
 *       //expensive FTPFile objects not created until needed.
 *    }
 * </pre>
 * <p>
 * For examples of using FTPClient on servers whose directory listings
 * <ul>
 * <li>use languages other than English</li>
 * <li>use date formats other than the American English "standard" <code>MM d yyyy</code></li>
 * <li>are in different time zones and you need accurate timestamps for dependency checking
 *     as in Ant</li>
 * </ul>see {@link  FTPClientConfig  FTPClientConfig}.
 * <p>
 * <b>Control channel keep-alive feature</b>:
 * <p>
 * <b>Please note:</b> this does not apply to the methods where the user is responsible for writing or reading
 * the data stream, i.e. {@link #retrieveFileStream(String)} , {@link #storeFileStream(String)}
 * and the other xxxFileStream methods
 * <p>
 * During file transfers, the data connection is busy, but the control connection is idle.
 * FTP servers know that the control connection is in use, so won't close it through lack of activity,
 * but it's a lot harder for network routers to know that the control and data connections are associated
 * with each other.
 * Some routers may treat the control connection as idle, and disconnect it if the transfer over the data
 * connection takes longer than the allowable idle time for the router.
 * <br>
 * One solution to this is to send a safe command (i.e. NOOP) over the control connection to reset the router's
 * idle timer. This is enabled as follows:
 * <pre>
 *     ftpClient.setControlKeepAliveTimeout(300); // set timeout to 5 minutes
 * </pre>
 * This will cause the file upload/download methods to send a NOOP approximately every 5 minutes.
 * The following public methods support this:
 * <ul>
 * <li>{@link #retrieveFile(String, OutputStream)}</li>
 * <li>{@link #appendFile(String, InputStream)}</li>
 * <li>{@link #storeFile(String, InputStream)}</li>
 * <li>{@link #storeUniqueFile(InputStream)}</li>
 * <li>{@link #storeUniqueFileStream(String)}</li>
 * </ul>
 * This feature does not apply to the methods where the user is responsible for writing or reading
 * the data stream, i.e. {@link #retrieveFileStream(String)} , {@link #storeFileStream(String)}
 * and the other xxxFileStream methods.
 * In such cases, the user is responsible for keeping the control connection alive if necessary.
 * <p>
 * The implementation currently uses a {@link CopyStreamListener} which is passed to the
 * {@link Util#copyStream(InputStream, OutputStream, int, long, CopyStreamListener, boolean)}
 * method, so the timing is partially dependent on how long each block transfer takes.
 * <p>
 * <b>This keep-alive feature is optional; if it does not help or causes problems then don't use it.</b>
 *
 * @see #FTP_SYSTEM_TYPE
 * @see #SYSTEM_TYPE_PROPERTIES
 * @see FTP
 * @see FTPConnectionClosedException
 * @see FTPFileEntryParser
 * @see FTPFileEntryParserFactory
 * @see DefaultFTPFileEntryParserFactory
 * @see FTPClientConfig
 *
 * @see org.apache.commons.net.MalformedServerReplyException
 */
public class FTPClient extends FTP implements Configurable {
    // @since 3.0
    private static class CSL implements CopyStreamListener {

        private final FTPClient parent;
        private final long idleMillis;
        private final int currentSoTimeoutMillis;

        private long timeMillis = System.currentTimeMillis();
        private int notAcked;
        private int acksAcked;
        private int ioErrors;

        CSL(final FTPClient parent, final long idleTimeMillis, final int maxWaitMillis) throws SocketException {
            this.idleMillis = idleTimeMillis;
            this.parent = parent;
            this.currentSoTimeoutMillis = parent.getSoTimeout();
            parent.setSoTimeout(maxWaitMillis);
        }

        @Override
        public void bytesTransferred(final CopyStreamEvent event) {
            bytesTransferred(event.getTotalBytesTransferred(), event.getBytesTransferred(), event.getStreamSize());
        }

        @Override
        public void bytesTransferred(final long totalBytesTransferred,
                final int bytesTransferred, final long streamSize) {
            final long nowMillis = System.currentTimeMillis();
            if (nowMillis - timeMillis > idleMillis) {
                try {
                    parent.__noop();
                    acksAcked++;
                } catch (final SocketTimeoutException e) {
                    notAcked++;
                } catch (final IOException e) {
                    ioErrors++;
                    // Ignored
                }
                timeMillis = nowMillis;
            }
        }

        int[] cleanUp() throws IOException {
            final int remain = notAcked;
            try {
                while(notAcked > 0) {
                    parent.getReply(); // we do want to see these
                    notAcked--; // only decrement if actually received
                }
            } catch (final SocketTimeoutException e) { // NET-584
                // ignored
            } finally {
                parent.setSoTimeout(currentSoTimeoutMillis);
            }
            return new int [] {acksAcked, remain, notAcked, ioErrors}; // debug counts
        }

    }

    /**
     * Strategy interface for updating host names received from FTP server
     * for passive NAT workaround.
     *
     * @since 3.6
     */
    public interface HostnameResolver {
        String resolve(String hostname) throws UnknownHostException;
    }

    /**
     * Default strategy for passive NAT workaround (site-local
     * replies are replaced.)
     * @since 3.6
     */
    public static class NatServerResolverImpl implements HostnameResolver {
        private final FTPClient client;

        public NatServerResolverImpl(final FTPClient client) {
            this.client = client;
        }

        @Override
        public String resolve(final String hostname) throws UnknownHostException {
            String newHostname = hostname;
            final InetAddress host = InetAddress.getByName(newHostname);
            // reply is a local address, but target is not - assume NAT box changed the PASV reply
            if (host.isSiteLocalAddress()) {
                final InetAddress remote = this.client.getRemoteAddress();
                if (!remote.isSiteLocalAddress()){
                    newHostname = remote.getHostAddress();
                }
            }
            return newHostname;
        }
    }

    private static class PropertiesSingleton {

        static final Properties PROPERTIES;

        static {
            final InputStream resourceAsStream = FTPClient.class.getResourceAsStream(SYSTEM_TYPE_PROPERTIES);
            Properties p = null;
            if (resourceAsStream != null) {
                p = new Properties();
                try {
                    p.load(resourceAsStream);
                } catch (final IOException e) {
                    // Ignored
                } finally {
                    try {
                        resourceAsStream.close();
                    } catch (final IOException e) {
                        // Ignored
                    }
                }
            }
            PROPERTIES = p;
        }

    }

    /**
     * The system property ({@value}) which can be used to override the system type.<br>
     * If defined, the value will be used to create any automatically created parsers.
     *
     * @since 3.0
     */
    public static final String FTP_SYSTEM_TYPE = "org.apache.commons.net.ftp.systemType";

    /**
     * The system property ({@value}) which can be used as the default system type.<br>
     * If defined, the value will be used if the SYST command fails.
     *
     * @since 3.1
     */
    public static final String FTP_SYSTEM_TYPE_DEFAULT = "org.apache.commons.net.ftp.systemType.default";

    /**
     * The name of an optional systemType properties file ({@value}), which is loaded
     * using {@link Class#getResourceAsStream(String)}.<br>
     * The entries are the systemType (as determined by {@link FTPClient#getSystemType})
     * and the values are the replacement type or parserClass, which is passed to
     * {@link FTPFileEntryParserFactory#createFileEntryParser(String)}.<br>
     * For example:
     * <pre>
     * Plan 9=Unix
     * OS410=org.apache.commons.net.ftp.parser.OS400FTPEntryParser
     * </pre>
     *
     * @since 3.0
     */
    public static final String SYSTEM_TYPE_PROPERTIES = "/systemType.properties";

    /**
     * A constant indicating the FTP session is expecting all transfers
     * to occur between the client (local) and server and that the server
     * should connect to the client's data port to initiate a data transfer.
     * This is the default data connection mode when and FTPClient instance
     * is created.
     */
    public static final int ACTIVE_LOCAL_DATA_CONNECTION_MODE = 0;

    /**
     * A constant indicating the FTP session is expecting all transfers
     * to occur between two remote servers and that the server
     * the client is connected to should connect to the other server's
     * data port to initiate a data transfer.
     */
    public static final int ACTIVE_REMOTE_DATA_CONNECTION_MODE = 1;

    /**
     * A constant indicating the FTP session is expecting all transfers
     * to occur between the client (local) and server and that the server
     * is in passive mode, requiring the client to connect to the
     * server's data port to initiate a transfer.
     */
    public static final int PASSIVE_LOCAL_DATA_CONNECTION_MODE = 2;

    /**
     * A constant indicating the FTP session is expecting all transfers
     * to occur between two remote servers and that the server
     * the client is connected to is in passive mode, requiring the other
     * server to connect to the first server's data port to initiate a data
     * transfer.
     */
    public static final int PASSIVE_REMOTE_DATA_CONNECTION_MODE = 3;

    /** Pattern for PASV mode responses. Groups: (n,n,n,n),(n),(n) */
    private static final java.util.regex.Pattern PARMS_PAT;

    static {
        PARMS_PAT = java.util.regex.Pattern.compile(
                "(\\d{1,3},\\d{1,3},\\d{1,3},\\d{1,3}),(\\d{1,3}),(\\d{1,3})");
    }

    private static Properties getOverrideProperties() {
        return PropertiesSingleton.PROPERTIES;
    }

    /**
     * Parse the pathname from a CWD reply.
     * <p>
     * According to RFC959 (http://www.ietf.org/rfc/rfc959.txt),
     * it should be the same as for MKD i.e.
     * {@code 257<space>"<directory-name>"[<space>commentary]}
     * where any double-quotes in {@code <directory-name>} are doubled.
     * Unlike MKD, the commentary is optional.
     * <p>
     * However, see NET-442 for an exception.
     *
     * @param reply
     * @return the pathname, without enclosing quotes,
     * or the full string after the reply code and space if the syntax is invalid
     * (i.e. enclosing quotes are missing or embedded quotes are not doubled)
     */
    // package protected for access by test cases
    static String parsePathname(final String reply)
    {
        final String param = reply.substring(REPLY_CODE_LEN + 1);
        if (param.startsWith("\"")) {
            final StringBuilder sb = new StringBuilder();
            boolean quoteSeen = false;
            // start after initial quote
            for(int i=1; i < param.length(); i++) {
                final char ch = param.charAt(i);
                if (ch=='"') {
                    if (quoteSeen) {
                        sb.append(ch);
                        quoteSeen=false;
                    } else {
                        // don't output yet, in case doubled
                        quoteSeen=true;
                    }
                } else {
                    if (quoteSeen) { // found lone trailing quote within string
                        return sb.toString();
                    }
                    sb.append(ch); // just another character
                }
            }
            if (quoteSeen) { // found lone trailing quote at end of string
                return sb.toString();
            }
        }
        // malformed reply, return all after reply code and space
        return param;
    }

    private int dataConnectionMode;
    private int dataTimeoutMillis;

    private int passivePort;
    private String passiveHost;
    private final Random random;
    private int activeMinPort;
    private int activeMaxPort;
    private InetAddress activeExternalHost;

    /** overrides __activeExternalHost in EPRT/PORT commands. */
    private InetAddress reportActiveExternalHost;

    /** The address to bind to on passive connections, if necessary. */
    private InetAddress passiveLocalHost;
    private int fileType;
    @SuppressWarnings("unused") // fields are written, but currently not read
    private int fileFormat;
    @SuppressWarnings("unused") // field is written, but currently not read
    private int fileStructure;
    @SuppressWarnings("unused") // field is written, but currently not read
    private int fileTransferMode;

    private boolean remoteVerificationEnabled;

    private long restartOffset;

    private FTPFileEntryParserFactory parserFactory;

    private int bufferSize; // buffersize for buffered data streams

    private int sendDataSocketBufferSize;

    private int receiveDataSocketBufferSize;

    private boolean listHiddenFiles;

    private boolean useEPSVwithIPv4; // whether to attempt EPSV with an IPv4 connection

    // __systemName is a cached value that should not be referenced directly
    // except when assigned in getSystemName and __initDefaults.
    private String systemName;

    // __entryParser is a cached value that should not be referenced directly
    // except when assigned in listFiles(String, String) and __initDefaults.
    private FTPFileEntryParser entryParser;

    // Key used to create the parser; necessary to ensure that the parser type is not ignored
    private String entryParserKey;

    private FTPClientConfig configuration;

    // Listener used by store/retrieve methods to handle keepalive
    private CopyStreamListener copyStreamListener;

    // How long to wait before sending another control keep-alive message
    private long controlKeepAliveTimeoutMillis;
    // How long to wait (millis) for keepalive message replies before continuing
    // Most FTP servers don't seem to support concurrent control and data connection usage
    private int controlKeepAliveReplyTimeoutMillis = 1000;

    // Debug counts for NOOP acks
    private int[] cslDebug;


    /**
     * Enable or disable replacement of internal IP in passive mode. Default enabled
     * using {code NatServerResolverImpl}.
     */
    private HostnameResolver passiveNatWorkaroundStrategy = new NatServerResolverImpl(this);

    /** Controls the automatic server encoding detection (only UTF-8 supported). */
    private boolean autodetectEncoding = false;

    /** Map of FEAT responses. If null, has not been initialized. */
    private HashMap<String, Set<String>> featuresMap;

    /**
     * Default FTPClient constructor.  Creates a new FTPClient instance
     * with the data connection mode set to
     * <code> ACTIVE_LOCAL_DATA_CONNECTION_MODE </code>, the file type
     * set to <code> FTP.ASCII_FILE_TYPE </code>, the
     * file format set to <code> FTP.NON_PRINT_TEXT_FORMAT </code>,
     * the file structure set to <code> FTP.FILE_STRUCTURE </code>, and
     * the transfer mode set to <code> FTP.STREAM_TRANSFER_MODE </code>.
     * <p>
     * The list parsing auto-detect feature can be configured to use lenient future
     * dates (short dates may be up to one day in the future) as follows:
     * <pre>
     * FTPClient ftp = new FTPClient();
     * FTPClientConfig config = new FTPClientConfig();
     * config.setLenientFutureDates(true);
     * ftp.configure(config );
     * </pre>
     */
    public FTPClient()
    {
        initDefaults();
        dataTimeoutMillis = -1;
        remoteVerificationEnabled = true;
        parserFactory = new DefaultFTPFileEntryParserFactory();
        configuration      = null;
        listHiddenFiles = false;
        useEPSVwithIPv4 = false;
        random = new Random();
        passiveLocalHost   = null;
    }

    @Override
    protected void _connectAction_() throws IOException {
        _connectAction_(null);
    }

    /**
     * @param socketIsReader the reader to reuse (if non-null)
     * @throws IOException on error
     * @since 3.4
     */
    @Override
    protected void _connectAction_(final Reader socketIsReader) throws IOException {
        super._connectAction_(socketIsReader); // sets up _input_ and _output_
        initDefaults();
        // must be after super._connectAction_(), because otherwise we get an
        // Exception claiming we're not connected
        if (autodetectEncoding) {
            final ArrayList<String> oldReplyLines = new ArrayList<>(_replyLines);
            final int oldReplyCode = _replyCode;
            if (hasFeature("UTF8") || hasFeature("UTF-8")) // UTF8 appears to be the default
            {
                setControlEncoding("UTF-8");
                _controlInput_ = new CRLFLineReader(new InputStreamReader(_input_, getControlEncoding()));
                _controlOutput_ = new BufferedWriter(new OutputStreamWriter(_output_, getControlEncoding()));
            }
            // restore the original reply (server greeting)
            _replyLines.clear();
            _replyLines.addAll(oldReplyLines);
            _replyCode = oldReplyCode;
            _newReplyString = true;
        }
    }

    /**
     * Establishes a data connection with the FTP server, returning
     * a Socket for the connection if successful.  If a restart
     * offset has been set with {@link #setRestartOffset(long)},
     * a REST command is issued to the server with the offset as
     * an argument before establishing the data connection.  Active
     * mode connections also cause a local PORT command to be issued.
     *
     * @param command  The int representation of the FTP command to send.
     * @param arg The arguments to the FTP command.  If this parameter is
     *             set to null, then the command is sent with no argument.
     * @return A Socket corresponding to the established data connection.
     *         Null is returned if an FTP protocol error is reported at
     *         any point during the establishment and initialization of
     *         the connection.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.3
     */
    protected Socket _openDataConnection_(final FTPCmd command, final String arg)
    throws IOException
    {
        return _openDataConnection_(command.getCommand(), arg);
    }

    /**
     * Establishes a data connection with the FTP server, returning
     * a Socket for the connection if successful.  If a restart
     * offset has been set with {@link #setRestartOffset(long)},
     * a REST command is issued to the server with the offset as
     * an argument before establishing the data connection.  Active
     * mode connections also cause a local PORT command to be issued.
     *
     * @param command  The int representation of the FTP command to send.
     * @param arg The arguments to the FTP command.  If this parameter is
     *             set to null, then the command is sent with no argument.
     * @return A Socket corresponding to the established data connection.
     *         Null is returned if an FTP protocol error is reported at
     *         any point during the establishment and initialization of
     *         the connection.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @deprecated (3.3) Use {@link #_openDataConnection_(FTPCmd, String)} instead
     */
    @Deprecated
    protected Socket _openDataConnection_(final int command, final String arg) throws IOException {
        return _openDataConnection_(FTPCommand.getCommand(command), arg);
    }

    /**
     * Establishes a data connection with the FTP server, returning
     * a Socket for the connection if successful.  If a restart
     * offset has been set with {@link #setRestartOffset(long)},
     * a REST command is issued to the server with the offset as
     * an argument before establishing the data connection.  Active
     * mode connections also cause a local PORT command to be issued.
     *
     * @param command  The text representation of the FTP command to send.
     * @param arg The arguments to the FTP command.  If this parameter is
     *             set to null, then the command is sent with no argument.
     * @return A Socket corresponding to the established data connection.
     *         Null is returned if an FTP protocol error is reported at
     *         any point during the establishment and initialization of
     *         the connection.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.1
     */
    protected Socket _openDataConnection_(final String command, final String arg)
    throws IOException
    {
        if (dataConnectionMode != ACTIVE_LOCAL_DATA_CONNECTION_MODE &&
                dataConnectionMode != PASSIVE_LOCAL_DATA_CONNECTION_MODE) {
            return null;
        }

        final boolean isInet6Address = getRemoteAddress() instanceof Inet6Address;

        final Socket socket;

        if (dataConnectionMode == ACTIVE_LOCAL_DATA_CONNECTION_MODE)
        {
            // if no activePortRange was set (correctly) -> getActivePort() = 0
            // -> new ServerSocket(0) -> bind to any free local port
            try (final ServerSocket server = _serverSocketFactory_.createServerSocket(getActivePort(), 1, getHostAddress())) {
                // Try EPRT only if remote server is over IPv6, if not use PORT,
                // because EPRT has no advantage over PORT on IPv4.
                // It could even have the disadvantage,
                // that EPRT will make the data connection fail, because
                // today's intelligent NAT Firewalls are able to
                // substitute IP addresses in the PORT command,
                // but might not be able to recognize the EPRT command.
                if (isInet6Address) {
                    if (!FTPReply.isPositiveCompletion(eprt(getReportHostAddress(), server.getLocalPort()))) {
                        return null;
                    }
                } else {
                    if (!FTPReply.isPositiveCompletion(port(getReportHostAddress(), server.getLocalPort()))) {
                        return null;
                    }
                }

                if ((restartOffset > 0) && !restart(restartOffset)) {
                    return null;
                }

                if (!FTPReply.isPositivePreliminary(sendCommand(command, arg))) {
                    return null;
                }

                // For now, let's just use the data timeout value for waiting for
                // the data connection.  It may be desirable to let this be a
                // separately configurable value.  In any case, we really want
                // to allow preventing the accept from blocking indefinitely.
                if (dataTimeoutMillis >= 0) {
                    server.setSoTimeout(dataTimeoutMillis);
                }
                socket = server.accept();

                // Ensure the timeout is set before any commands are issued on the new socket
                if (dataTimeoutMillis >= 0) {
                    socket.setSoTimeout(dataTimeoutMillis);
                }
                if (receiveDataSocketBufferSize > 0) {
                    socket.setReceiveBufferSize(receiveDataSocketBufferSize);
                }
                if (sendDataSocketBufferSize > 0) {
                    socket.setSendBufferSize(sendDataSocketBufferSize);
                }
            }
        }
        else
        { // We must be in PASSIVE_LOCAL_DATA_CONNECTION_MODE

            // Try EPSV command first on IPv6 - and IPv4 if enabled.
            // When using IPv4 with NAT it has the advantage
            // to work with more rare configurations.
            // E.g. if FTP server has a static PASV address (external network)
            // and the client is coming from another internal network.
            // In that case the data connection after PASV command would fail,
            // while EPSV would make the client succeed by taking just the port.
            final boolean attemptEPSV = isUseEPSVwithIPv4() || isInet6Address;
            if (attemptEPSV && epsv() == FTPReply.ENTERING_EPSV_MODE)
            {
                _parseExtendedPassiveModeReply(_replyLines.get(0));
            }
            else
            {
                if (isInet6Address) {
                    return null; // Must use EPSV for IPV6
                }
                // If EPSV failed on IPV4, revert to PASV
                if (pasv() != FTPReply.ENTERING_PASSIVE_MODE) {
                    return null;
                }
                _parsePassiveModeReply(_replyLines.get(0));
            }

            socket = _socketFactory_.createSocket();
            if (receiveDataSocketBufferSize > 0) {
                socket.setReceiveBufferSize(receiveDataSocketBufferSize);
            }
            if (sendDataSocketBufferSize > 0) {
                socket.setSendBufferSize(sendDataSocketBufferSize);
            }
            if (passiveLocalHost != null) {
                socket.bind(new InetSocketAddress(passiveLocalHost, 0));
            }

            // For now, let's just use the data timeout value for waiting for
            // the data connection.  It may be desirable to let this be a
            // separately configurable value.  In any case, we really want
            // to allow preventing the accept from blocking indefinitely.
            if (dataTimeoutMillis >= 0) {
                socket.setSoTimeout(dataTimeoutMillis);
            }

            socket.connect(new InetSocketAddress(passiveHost, passivePort), connectTimeout);
            if ((restartOffset > 0) && !restart(restartOffset))
            {
                socket.close();
                return null;
            }

            if (!FTPReply.isPositivePreliminary(sendCommand(command, arg)))
            {
                socket.close();
                return null;
            }
        }

        if (remoteVerificationEnabled && !verifyRemote(socket))
        {
            // Grab the host before we close the socket to avoid NET-663
            final InetAddress socketHost = socket.getInetAddress();

            socket.close();

            throw new IOException(
                    "Host attempting data connection " + socketHost.getHostAddress() +
                    " is not same as server " + getRemoteAddress().getHostAddress());
        }

        return socket;
    }

    protected void _parseExtendedPassiveModeReply(String reply) throws MalformedServerReplyException {
        reply = reply.substring(reply.indexOf('(') + 1, reply.indexOf(')')).trim();

        final char delim1 = reply.charAt(0);
        final char delim2 = reply.charAt(1);
        final char delim3 = reply.charAt(2);
        final char delim4 = reply.charAt(reply.length() - 1);

        if ((delim1 != delim2) || (delim2 != delim3) || (delim3 != delim4)) {
            throw new MalformedServerReplyException(
                "Could not parse extended passive host information.\nServer Reply: " + reply);
        }

        final int port;
        try {
            port = Integer.parseInt(reply.substring(3, reply.length() - 1));
        } catch (final NumberFormatException e) {
            throw new MalformedServerReplyException(
                "Could not parse extended passive host information.\nServer Reply: " + reply);
        }

        // in EPSV mode, the passive host address is implicit
        this.passiveHost = getRemoteAddress().getHostAddress();
        this.passivePort = port;
    }

    /**
     * @since 3.1
     * @param reply the reply to parse
     * @throws MalformedServerReplyException if the server reply does not match  (n,n,n,n),(n),(n)
     */
    protected void _parsePassiveModeReply(final String reply) throws MalformedServerReplyException {
        final Matcher m = PARMS_PAT.matcher(reply);
        if (!m.find()) {
            throw new MalformedServerReplyException(
                "Could not parse passive host information.\nServer Reply: " + reply);
        }

        this.passiveHost = "0,0,0,0".equals(m.group(1)) ? _socket_.getInetAddress().getHostAddress()
            : m.group(1).replace(',', '.'); // Fix up to look like IP address

        try {
            final int oct1 = Integer.parseInt(m.group(2));
            final int oct2 = Integer.parseInt(m.group(3));
            passivePort = (oct1 << 8) | oct2;
        } catch (final NumberFormatException e) {
            throw new MalformedServerReplyException(
                "Could not parse passive port information.\nServer Reply: " + reply);
        }

        if (passiveNatWorkaroundStrategy != null) {
            try {
                final String newPassiveHost = passiveNatWorkaroundStrategy.resolve(this.passiveHost);
                if (!this.passiveHost.equals(newPassiveHost)) {
                    fireReplyReceived(0,
                        "[Replacing PASV mode reply address " + this.passiveHost + " with " + newPassiveHost + "]\n");
                    this.passiveHost = newPassiveHost;
                }
            } catch (final UnknownHostException e) { // Should not happen as we are passing in an IP address
                throw new MalformedServerReplyException(
                    "Could not parse passive host information.\nServer Reply: " + reply);
            }
        }
    }

    /**
     * @param command the command to get
     * @param remote the remote file name
     * @param local The local OutputStream to which to write the file.
     * @return true if successful
     * @throws IOException on error
     * @since 3.1
     */
    protected boolean _retrieveFile(final String command, final String remote, final OutputStream local)
    throws IOException
    {
        final Socket socket = _openDataConnection_(command, remote);

        if (socket == null) {
            return false;
        }

        InputStream input = null;
        CSL csl = null;
        try {
            try {
                if (fileType == ASCII_FILE_TYPE) {
                    input = new FromNetASCIIInputStream(getBufferedInputStream(socket.getInputStream()));
                } else {
                    input = getBufferedInputStream(socket.getInputStream());
                }

                if (controlKeepAliveTimeoutMillis > 0) {
                    csl = new CSL(this, controlKeepAliveTimeoutMillis, controlKeepAliveReplyTimeoutMillis);
                }

                // Treat everything else as binary for now
                Util.copyStream(input, local, getBufferSize(), CopyStreamEvent.UNKNOWN_STREAM_SIZE, mergeListeners(csl),
                    false);
            } finally {
                Util.closeQuietly(input);
            }
            // Get the transfer response
            return completePendingCommand();
        } finally {
            Util.closeQuietly(socket);
            if (csl != null) {
                cslDebug = csl.cleanUp(); // fetch any outstanding keepalive replies
            }
        }
    }


    /**
     * @param command the command to send
     * @param remote the remote file name
     * @return the stream from which to read the file
     * @throws IOException on error
     * @since 3.1
     */
    protected InputStream _retrieveFileStream(final String command, final String remote)
    throws IOException
    {
        final Socket socket = _openDataConnection_(command, remote);

        if (socket == null) {
            return null;
        }

        final InputStream input;
        if (fileType == ASCII_FILE_TYPE) {
            // We buffer ascii transfers because the buffering has to
            // be interposed between FromNetASCIIOutputSream and the underlying
            // socket input stream.  We don't buffer binary transfers
            // because we don't want to impose a buffering policy on the
            // programmer if possible.  Programmers can decide on their
            // own if they want to wrap the SocketInputStream we return
            // for file types other than ASCII.
            input = new FromNetASCIIInputStream(getBufferedInputStream(socket.getInputStream()));
        } else {
            input = socket.getInputStream();
        }
        return new org.apache.commons.net.io.SocketInputStream(socket, input);
    }


    /**
     * @since 3.1
     * @param command the command to send
     * @param remote the remote file name
     * @param local The local InputStream from which to read the data to
     *                be written/appended to the remote file.
     * @return true if successful
     * @throws IOException on error
     */
    protected boolean _storeFile(final String command, final String remote, final InputStream local)
    throws IOException
    {
        final Socket socket = _openDataConnection_(command, remote);

        if (socket == null) {
            return false;
        }

        final OutputStream output;

        if (fileType == ASCII_FILE_TYPE) {
            output = new ToNetASCIIOutputStream(getBufferedOutputStream(socket.getOutputStream()));
        } else {
            output = getBufferedOutputStream(socket.getOutputStream());
        }

        CSL csl = null;
        if (controlKeepAliveTimeoutMillis > 0) {
            csl = new CSL(this, controlKeepAliveTimeoutMillis, controlKeepAliveReplyTimeoutMillis);
        }

        // Treat everything else as binary for now
        try
        {
            Util.copyStream(local, output, getBufferSize(),
                    CopyStreamEvent.UNKNOWN_STREAM_SIZE, mergeListeners(csl),
                    false);
            output.close(); // ensure the file is fully written
            socket.close(); // done writing the file

            // Get the transfer response
            return completePendingCommand();
        }
        catch (final IOException e)
        {
            Util.closeQuietly(output); // ignore close errors here
            Util.closeQuietly(socket); // ignore close errors here
            throw e;
        } finally {
            if (csl != null) {
                cslDebug = csl.cleanUp(); // fetch any outstanding keepalive replies
            }
        }
    }

    /**
     * @param command the command to send
     * @param remote the remote file name
     * @return the output stream to write to
     * @throws IOException on error
     * @since 3.1
     */
    protected OutputStream _storeFileStream(final String command, final String remote)
    throws IOException
    {
        final Socket socket = _openDataConnection_(command, remote);

        if (socket == null) {
            return null;
        }

        final OutputStream output;
        if (fileType == ASCII_FILE_TYPE) {
            // We buffer ascii transfers because the buffering has to
            // be interposed between ToNetASCIIOutputSream and the underlying
            // socket output stream.  We don't buffer binary transfers
            // because we don't want to impose a buffering policy on the
            // programmer if possible.  Programmers can decide on their
            // own if they want to wrap the SocketOutputStream we return
            // for file types other than ASCII.
            output = new ToNetASCIIOutputStream(getBufferedOutputStream(socket.getOutputStream()));
        } else {
            output = socket.getOutputStream();
        }
        return new SocketOutputStream(socket, output);
    }

    /**
     * Abort a transfer in progress.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean abort() throws IOException
    {
        return FTPReply.isPositiveCompletion(abor());
    }

    /**
     * Reserve a number of bytes on the server for the next file transfer.
     *
     * @param bytes  The number of bytes which the server should allocate.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean allocate(final int bytes) throws IOException
    {
        return FTPReply.isPositiveCompletion(allo(bytes));
    }

    /**
     * Reserve space on the server for the next file transfer.
     *
     * @param bytes  The number of bytes which the server should allocate.
     * @param recordSize  The size of a file record.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean allocate(final int bytes, final int recordSize) throws IOException
    {
        return FTPReply.isPositiveCompletion(allo(bytes, recordSize));
    }

    /**
     * Reserve a number of bytes on the server for the next file transfer.
     *
     * @param bytes  The number of bytes which the server should allocate.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean allocate(final long bytes) throws IOException
    {
        return FTPReply.isPositiveCompletion(allo(bytes));
    }

    /**
     * Reserve space on the server for the next file transfer.
     *
     * @param bytes  The number of bytes which the server should allocate.
     * @param recordSize  The size of a file record.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean allocate(final long bytes, final int recordSize) throws IOException
    {
        return FTPReply.isPositiveCompletion(allo(bytes, recordSize));
    }

    /**
     * Appends to a file on the server with the given name, taking input
     * from the given InputStream.  This method does NOT close the given
     * InputStream.  If the current file type is ASCII, line separators in
     * the file are transparently converted to the NETASCII format (i.e.,
     * you should not attempt to create a special InputStream to do this).
     *
     * @param remote  The name of the remote file.
     * @param local   The local InputStream from which to read the data to
     *                be appended to the remote file.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws org.apache.commons.net.io.CopyStreamException
     *      If an I/O error occurs while actually
     *      transferring the file.  The CopyStreamException allows you to
     *      determine the number of bytes transferred and the IOException
     *      causing the error.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean appendFile(final String remote, final InputStream local)
    throws IOException
    {
        return storeFile(FTPCmd.APPE, remote, local);
    }

    /**
     * Returns an OutputStream through which data can be written to append
     * to a file on the server with the given name.  If the current file type
     * is ASCII, the returned OutputStream will convert line separators in
     * the file to the NETASCII format  (i.e., you should not attempt to
     * create a special OutputStream to do this).  You must close the
     * OutputStream when you finish writing to it.  The OutputStream itself
     * will take care of closing the parent data connection socket upon being
     * closed.
     * <p>
     * <b>To finalize the file transfer you must call
     * {@link #completePendingCommand  completePendingCommand } and
     * check its return value to verify success.</b>
     * If this is not done, subsequent commands may behave unexpectedly.
     *
     * @param remote  The name of the remote file.
     * @return An OutputStream through which the remote file can be appended.
     *      If the data connection cannot be opened (e.g., the file does not
     *      exist), null is returned (in which case you may check the reply
     *      code to determine the exact reason for failure).
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public OutputStream appendFileStream(final String remote) throws IOException
    {
        return storeFileStream(FTPCmd.APPE, remote);
    }


    /**
     * Change to the parent directory of the current working directory.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean changeToParentDirectory() throws IOException
    {
        return FTPReply.isPositiveCompletion(cdup());
    }


    /**
     * Change the current working directory of the FTP session.
     *
     * @param pathname  The new current working directory.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean changeWorkingDirectory(final String pathname) throws IOException
    {
        return FTPReply.isPositiveCompletion(cwd(pathname));
    }

    /**
     * There are a few FTPClient methods that do not complete the
     * entire sequence of FTP commands to complete a transaction.  These
     * commands require some action by the programmer after the reception
     * of a positive intermediate command.  After the programmer's code
     * completes its actions, it must call this method to receive
     * the completion reply from the server and verify the success of the
     * entire transaction.
     * <p>
     * For example,
     * <pre>
     * InputStream input;
     * OutputStream output;
     * input  = new FileInputStream("foobaz.txt");
     * output = ftp.storeFileStream("foobar.txt")
     * if(!FTPReply.isPositiveIntermediate(ftp.getReplyCode())) {
     *     input.close();
     *     output.close();
     *     ftp.logout();
     *     ftp.disconnect();
     *     System.err.println("File transfer failed.");
     *     System.exit(1);
     * }
     * Util.copyStream(input, output);
     * input.close();
     * output.close();
     * // Must call completePendingCommand() to finish command.
     * if(!ftp.completePendingCommand()) {
     *     ftp.logout();
     *     ftp.disconnect();
     *     System.err.println("File transfer failed.");
     *     System.exit(1);
     * }
     * </pre>
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean completePendingCommand() throws IOException
    {
        return FTPReply.isPositiveCompletion(getReply());
    }

    /**
     * Implementation of the {@link Configurable Configurable} interface.
     * In the case of this class, configuring merely makes the config object available for the
     * factory methods that construct parsers.
     * @param config {@link FTPClientConfig FTPClientConfig} object used to
     * provide non-standard configurations to the parser.
     * @since 1.4
     */
    @Override
    public void configure(final FTPClientConfig config) {
        this.configuration = config;
    }

    // package access for test purposes
    void createParser(final String parserKey) throws IOException {
        // We cache the value to avoid creation of a new object every
        // time a file listing is generated.
        // Note: we don't check against a null parserKey (NET-544)
        if(entryParser == null ||  (parserKey != null && ! entryParserKey.equals(parserKey))) {
            if (null != parserKey) {
                // if a parser key was supplied in the parameters,
                // use that to create the parser
                entryParser =
                    parserFactory.createFileEntryParser(parserKey);
                entryParserKey = parserKey;

            } else {
                // if no parserKey was supplied, check for a configuration
                // in the params, and if it has a non-empty system type, use that.
                if (null != configuration && configuration.getServerSystemKey().length() > 0) {
                    entryParser =
                        parserFactory.createFileEntryParser(configuration);
                    entryParserKey = configuration.getServerSystemKey();
                } else {
                    // if a parserKey hasn't been supplied, and a configuration
                    // hasn't been supplied, and the override property is not set
                    // then autodetect by calling
                    // the SYST command and use that to choose the parser.
                    String systemType = System.getProperty(FTP_SYSTEM_TYPE);
                    if (systemType == null) {
                        systemType = getSystemType(); // cannot be null
                        final Properties override = getOverrideProperties();
                        if (override != null) {
                            final String newType = override.getProperty(systemType);
                            if (newType != null) {
                                systemType = newType;
                            }
                        }
                    }
                    if (null != configuration) { // system type must have been empty above
                        entryParser = parserFactory.createFileEntryParser(new FTPClientConfig(systemType, configuration));
                    } else {
                        entryParser = parserFactory.createFileEntryParser(systemType);
                    }
                    entryParserKey = systemType;
                }
            }
        }
    }

    /**
     * Deletes a file on the FTP server.
     *
     * @param pathname   The pathname of the file to be deleted.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean deleteFile(final String pathname) throws IOException
    {
        return FTPReply.isPositiveCompletion(dele(pathname));
    }

    /**
     * Closes the connection to the FTP server and restores
     * connection parameters to the default values.
     *
     * @throws IOException If an error occurs while disconnecting.
     */
    @Override
    public void disconnect() throws IOException
    {
        super.disconnect();
        initDefaults();
    }

    /**
     * Issue a command and wait for the reply.
     * <p>
     * Should only be used with commands that return replies on the
     * command channel - do not use for LIST, NLST, MLSD etc.
     *
     * @param command  The command to invoke
     * @param params  The parameters string, may be {@code null}
     * @return True if successfully completed, false if not, in which case
     * call {@link #getReplyCode()} or {@link #getReplyString()}
     * to get the reason.
     *
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.0
     */
    public boolean doCommand(final String command, final String params) throws IOException
    {
        return FTPReply.isPositiveCompletion(sendCommand(command, params));
    }

    /**
     * Issue a command and wait for the reply, returning it as an array of strings.
     * <p>
     * Should only be used with commands that return replies on the
     * command channel - do not use for LIST, NLST, MLSD etc.
     *
     * @param command  The command to invoke
     * @param params  The parameters string, may be {@code null}
     * @return The array of replies, or {@code null} if the command failed, in which case
     * call {@link #getReplyCode()} or {@link #getReplyString()}
     * to get the reason.
     *
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.0
     */
    public String[] doCommandAsStrings(final String command, final String params) throws IOException
    {
        final boolean success = FTPReply.isPositiveCompletion(sendCommand(command, params));
        if (success){
            return getReplyStrings();
        }
        return null;
    }

    /**
     * Set the current data connection mode to
     * <code>ACTIVE_LOCAL_DATA_CONNECTION_MODE</code>.  No communication
     * with the FTP server is conducted, but this causes all future data
     * transfers to require the FTP server to connect to the client's
     * data port.  Additionally, to accommodate differences between socket
     * implementations on different platforms, this method causes the
     * client to issue a PORT command before every data transfer.
     */
    public void enterLocalActiveMode()
    {
        dataConnectionMode = ACTIVE_LOCAL_DATA_CONNECTION_MODE;
        passiveHost = null;
        passivePort = -1;
    }

    /**
     * Set the current data connection mode to
     * <code> PASSIVE_LOCAL_DATA_CONNECTION_MODE </code>.  Use this
     * method only for data transfers between the client and server.
     * This method causes a PASV (or EPSV) command to be issued to the server
     * before the opening of every data connection, telling the server to
     * open a data port to which the client will connect to conduct
     * data transfers.  The FTPClient will stay in
     * <code> PASSIVE_LOCAL_DATA_CONNECTION_MODE </code> until the
     * mode is changed by calling some other method such as
     * {@link #enterLocalActiveMode  enterLocalActiveMode() }
     * <p>
     * <b>N.B.</b> currently calling any connect method will reset the mode to
     * ACTIVE_LOCAL_DATA_CONNECTION_MODE.
     */
    public void enterLocalPassiveMode()
    {
        dataConnectionMode = PASSIVE_LOCAL_DATA_CONNECTION_MODE;
        // These will be set when just before a data connection is opened
        // in _openDataConnection_()
        passiveHost = null;
        passivePort = -1;
    }

    /**
     * Set the current data connection mode to
     * <code> ACTIVE_REMOTE_DATA_CONNECTION </code>.  Use this method only
     * for server to server data transfers.  This method issues a PORT
     * command to the server, indicating the other server and port to which
     * it should connect for data transfers.  You must call this method
     * before EVERY server to server transfer attempt.  The FTPClient will
     * NOT automatically continue to issue PORT commands.  You also
     * must remember to call
     * {@link #enterLocalActiveMode  enterLocalActiveMode() } if you
     * wish to return to the normal data connection mode.
     *
     * @param host The passive mode server accepting connections for data
     *             transfers.
     * @param port The passive mode server's data port.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean enterRemoteActiveMode(final InetAddress host, final int port)
    throws IOException
    {
        if (FTPReply.isPositiveCompletion(port(host, port)))
        {
            dataConnectionMode = ACTIVE_REMOTE_DATA_CONNECTION_MODE;
            passiveHost = null;
            passivePort = -1;
            return true;
        }
        return false;
    }

    /**
     * Set the current data connection mode to
     * <code> PASSIVE_REMOTE_DATA_CONNECTION_MODE </code>.  Use this
     * method only for server to server data transfers.
     * This method issues a PASV command to the server, telling it to
     * open a data port to which the active server will connect to conduct
     * data transfers.  You must call this method
     * before EVERY server to server transfer attempt.  The FTPClient will
     * NOT automatically continue to issue PASV commands.  You also
     * must remember to call
     * {@link #enterLocalActiveMode  enterLocalActiveMode() } if you
     * wish to return to the normal data connection mode.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean enterRemotePassiveMode() throws IOException
    {
        if (pasv() != FTPReply.ENTERING_PASSIVE_MODE) {
            return false;
        }

        dataConnectionMode = PASSIVE_REMOTE_DATA_CONNECTION_MODE;
        _parsePassiveModeReply(_replyLines.get(0));

        return true;
    }

    /**
     * Queries the server for supported features. The server may reply with a list of server-supported extensions.
     * For example, a typical client-server interaction might be (from RFC 2389):
     * <pre>
        C&gt; feat
        S&gt; 211-Extensions supported:
        S&gt;  MLST size*;create;modify*;perm;media-type
        S&gt;  SIZE
        S&gt;  COMPRESSION
        S&gt;  MDTM
        S&gt; 211 END
     * </pre>
     * @see <a href="http://www.faqs.org/rfcs/rfc2389.html">http://www.faqs.org/rfcs/rfc2389.html</a>
     * @return True if successfully completed, false if not.
     * @throws IOException on error
     * @since 2.2
     */
    public boolean features() throws IOException {
        return FTPReply.isPositiveCompletion(feat());
    }

    /**
     * Queries the server for a supported feature, and returns the its value (if any).
     * Caches the parsed response to avoid resending the command repeatedly.
     * @param feature the feature to check
     *
     * @return if the feature is present, returns the feature value or the empty string
     * if the feature exists but has no value.
     * Returns {@code null} if the feature is not found or the command failed.
     * Check {@link #getReplyCode()} or {@link #getReplyString()} if so.
     * @throws IOException on error
     * @since 3.0
     */
    public String featureValue(final String feature) throws IOException {
        final String [] values = featureValues(feature);
        if (values != null) {
            return values[0];
        }
        return null;
    }

    /**
     * Queries the server for a supported feature, and returns its values (if any).
     * Caches the parsed response to avoid resending the command repeatedly.
     * @param feature the feature to check
     *
     * @return if the feature is present, returns the feature values (empty array if none)
     * Returns {@code null} if the feature is not found or the command failed.
     * Check {@link #getReplyCode()} or {@link #getReplyString()} if so.
     * @throws IOException on error
     * @since 3.0
     */
    public String[] featureValues(final String feature) throws IOException {
        if (!initFeatureMap()) {
            return null;
        }
        final Set<String> entries = featuresMap.get(feature.toUpperCase(Locale.ENGLISH));
        if (entries != null) {
            return entries.toArray(NetConstants.EMPTY_STRING_ARRAY);
        }
        return null;
    }

    /**
     * Get the client port for active mode.
     *
     * @return The client port for active mode.
     */
    private int getActivePort()
    {
        if (activeMinPort > 0 && activeMaxPort >= activeMinPort)
        {
            if (activeMaxPort == activeMinPort) {
                return activeMaxPort;
            }
            // Get a random port between the min and max port range
            return random.nextInt(activeMaxPort - activeMinPort + 1) + activeMinPort;
        }
        // default port
        return 0;
    }

    /**
     * Tells if automatic server encoding detection is enabled or disabled.
     * @return true, if automatic server encoding detection is enabled.
     */
    public boolean getAutodetectUTF8()
    {
        return autodetectEncoding;
    }

    private InputStream getBufferedInputStream(final InputStream inputStream) {
        if (bufferSize > 0) {
            return new BufferedInputStream(inputStream, bufferSize);
        }
        return new BufferedInputStream(inputStream);
    }

    private OutputStream getBufferedOutputStream(final OutputStream outputStream) {
        if (bufferSize > 0) {
            return new BufferedOutputStream(outputStream, bufferSize);
        }
        return new BufferedOutputStream(outputStream);
    }

    /**
     * Retrieve the current internal buffer size for buffered data streams.
     * @return The current buffer size.
     */
    public int getBufferSize() {
        return bufferSize;
    }

    /**
     * Gets how long to wait for control keep-alive message replies.
     * @return wait time in milliseconds.
     * @since 3.0
     */
    public int getControlKeepAliveReplyTimeout() {
        return controlKeepAliveReplyTimeoutMillis;
    }

    /**
     * Gets the time to wait between sending control connection keepalive messages
     * when processing file upload or download.
     * <p>
     * See the class Javadoc section "Control channel keep-alive feature:"
     *
     * @return the number of seconds between keepalive messages.
     * @since 3.0
     */
    public long getControlKeepAliveTimeout() {
        return controlKeepAliveTimeoutMillis / 1000;
    }

    /**
     * Obtain the currently active listener.
     *
     * @return the listener, may be {@code null}
     * @since 3.0
     */
    public CopyStreamListener getCopyStreamListener(){
        return copyStreamListener;
    }

    /**
     * Get the CSL debug array.
     * <p>
     * <b>For debug use only</b>
     * <p>
     * Currently contains:
     * <ul>
     * <li>successfully acked NOOPs at end of transfer</li>
     * <li>unanswered NOOPs at end of transfer</li>
     * <li>unanswered NOOPs after fetching additional replies</li>
     * <li>Number of IOErrors ignored</li>
     * </ul>
     * @return the debug array
     * @deprecated 3.7 For testing only; may be dropped or changed at any time
     */
    @Deprecated // only for use in testing
    public int[] getCslDebug() {
        return cslDebug;
    }

    /**
     * Returns the current data connection mode (one of the
     * <code> _DATA_CONNECTION_MODE </code> constants.
     *
     * @return The current data connection mode (one of the
     * <code> _DATA_CONNECTION_MODE </code> constants.
     */
    public int getDataConnectionMode()
    {
        return dataConnectionMode;
    }

    // Method for use by unit test code only
    FTPFileEntryParser getEntryParser() {
        return entryParser;
    }

    /**
     * Get the host address for active mode; allows the local address to be overridden.
     *
     * @return __activeExternalHost if non-null, else getLocalAddress()
     * @see #setActiveExternalIPAddress(String)
     */
    private InetAddress getHostAddress()
    {
        if (activeExternalHost != null)
        {
            return activeExternalHost;
        }
        // default local address
        return getLocalAddress();
    }

    /**
     * @param pathname the initial pathname
     * @return the adjusted string with "-a" added if necessary
     * @since 2.0
     */
    protected String getListArguments(final String pathname) {
        if (getListHiddenFiles())
        {
            if (pathname != null)
            {
                final StringBuilder sb = new StringBuilder(pathname.length() + 3);
                sb.append("-a ");
                sb.append(pathname);
                return sb.toString();
            }
            return "-a";
        }

        return pathname;
    }

    /**
     * @see #setListHiddenFiles(boolean)
     * @return the current state
     * @since 2.0
     */
    public boolean getListHiddenFiles() {
        return this.listHiddenFiles;
    }

    /**
     * Issue the FTP MDTM command (not supported by all servers) to retrieve the last
     * modification time of a file. The modification string should be in the
     * ISO 3077 form "YYYYMMDDhhmmss(.xxx)?". The timestamp represented should also be in
     * GMT, but not all FTP servers honor this.
     *
     * @param pathname The file path to query.
     * @return A string representing the last file modification time in <code>YYYYMMDDhhmmss</code> format.
     * @throws IOException if an I/O error occurs.
     * @since 2.0
     */
    public String getModificationTime(final String pathname) throws IOException {
        if (FTPReply.isPositiveCompletion(mdtm(pathname))) {
            // skip the return code (e.g. 213) and the space
            return getReplyString(0).substring(4);
        }
        return null;
    }

    /**
     * Returns the hostname or IP address (in the form of a string) returned
     * by the server when entering passive mode.  If not in passive mode,
     * returns null.  This method only returns a valid value AFTER a
     * data connection has been opened after a call to
     * {@link #enterLocalPassiveMode enterLocalPassiveMode()}.
     * This is because FTPClient sends a PASV command to the server only
     * just before opening a data connection, and not when you call
     * {@link #enterLocalPassiveMode enterLocalPassiveMode()}.
     *
     * @return The passive host name if in passive mode, otherwise null.
     */
    public String getPassiveHost()
    {
        return passiveHost;
    }

    /**
     * Set the local IP address in passive mode.
     * Useful when there are multiple network cards.
     *
     * @return The local IP address in passive mode.
     */
    public InetAddress getPassiveLocalIPAddress()
    {
        return this.passiveLocalHost;
    }

    /**
     * If in passive mode, returns the data port of the passive host.
     * This method only returns a valid value AFTER a
     * data connection has been opened after a call to
     * {@link #enterLocalPassiveMode enterLocalPassiveMode()}.
     * This is because FTPClient sends a PASV command to the server only
     * just before opening a data connection, and not when you call
     * {@link #enterLocalPassiveMode enterLocalPassiveMode()}.
     *
     * @return The data port of the passive server.  If not in passive
     *         mode, undefined.
     */
    public int getPassivePort()
    {
        return passivePort;
    }

    /**
     * Retrieve the value to be used for the data socket SO_RCVBUF option.
     * @return The current buffer size.
     * @since 3.3
     */
    public int getReceiveDataSocketBufferSize() {
        return receiveDataSocketBufferSize;
    }

    /**
     * Get the reported host address for active mode EPRT/PORT commands;
     * allows override of {@link #getHostAddress()}.
     *
     * Useful for FTP Client behind Firewall NAT.
     *
     * @return __reportActiveExternalHost if non-null, else getHostAddress();
     */
    private InetAddress getReportHostAddress() {
        if (reportActiveExternalHost != null) {
            return reportActiveExternalHost ;
        }
        return getHostAddress();
    }

    /**
     * Fetches the restart offset.
     *
     * @return offset  The offset into the remote file at which to start the
     *           next file transfer.
     */
    public long getRestartOffset()
    {
        return restartOffset;
    }

    /**
     * Retrieve the value to be used for the data socket SO_SNDBUF option.
     * @return The current buffer size.
     * @since 3.3
     */
    public int getSendDataSocketBufferSize() {
        return sendDataSocketBufferSize;
    }

    /**
     * Issue the FTP SIZE command to the server for a given pathname.
     * This should produce the size of the file.
     *
     * @param pathname the file name
     *
     * @return The size information returned by the server; {@code null} if there was an error
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.7
     */
    public String getSize(final String pathname) throws IOException
    {
        if (FTPReply.isPositiveCompletion(size(pathname))) {
            return getReplyString(0).substring(4); // skip the return code (e.g. 213) and the space
        }
        return null;
    }

    /**
     * Issue the FTP STAT command to the server.
     *
     * @return The status information returned by the server.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public String getStatus() throws IOException
    {
        if (FTPReply.isPositiveCompletion(stat())) {
            return getReplyString();
        }
        return null;
    }

    /**
     * Issue the FTP STAT command to the server for a given pathname.  This
     * should produce a listing of the file or directory.
     * @param pathname the file name
     *
     * @return The status information returned by the server.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public String getStatus(final String pathname) throws IOException
    {
        if (FTPReply.isPositiveCompletion(stat(pathname))) {
            return getReplyString();
        }
        return null;
    }

    /**
     * @return the name
     * @throws IOException on error
     * @deprecated use {@link #getSystemType()} instead
     */
    @Deprecated
    public String getSystemName() throws IOException
    {
        if (systemName == null && FTPReply.isPositiveCompletion(syst())) {
            systemName = _replyLines.get(_replyLines.size() - 1).substring(4);
        }
        return systemName;
    }

    /**
     * Fetches the system type from the server and returns the string.
     * This value is cached for the duration of the connection after the
     * first call to this method.  In other words, only the first time
     * that you invoke this method will it issue a SYST command to the
     * FTP server.  FTPClient will remember the value and return the
     * cached value until a call to disconnect.
     * <p>
     * If the SYST command fails, and the system property
     * {@link #FTP_SYSTEM_TYPE_DEFAULT} is defined, then this is used instead.
     * @return The system type obtained from the server. Never null.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *  command to the server or receiving a reply from the server (and the default
     *  system type property is not defined)
     *  @since 2.2
     */
    public String getSystemType() throws IOException
    {
        //if (syst() == FTPReply.NAME_SYSTEM_TYPE)
        // Technically, we should expect a NAME_SYSTEM_TYPE response, but
        // in practice FTP servers deviate, so we soften the condition to
        // a positive completion.
        if (systemName == null){
            if (FTPReply.isPositiveCompletion(syst())) {
                // Assume that response is not empty here (cannot be null)
                systemName = _replyLines.get(_replyLines.size() - 1).substring(4);
            } else {
                // Check if the user has provided a default for when the SYST command fails
                final String systDefault = System.getProperty(FTP_SYSTEM_TYPE_DEFAULT);
                if (systDefault != null) {
                    systemName = systDefault;
                } else {
                    throw new IOException("Unable to determine system type - response: " + getReplyString());
                }
            }
        }
        return systemName;
    }

    /**
     * Queries the server for a supported feature.
     * Caches the parsed response to avoid resending the command repeatedly.
     *
     * @param feature the name of the feature; it is converted to upper case.
     * @return {@code true} if the feature is present, {@code false} if the feature is not present
     * or the {@link #feat()} command failed. Check {@link #getReplyCode()} or {@link #getReplyString()}
     * if it is necessary to distinguish these cases.
     *
     * @throws IOException on error
     * @since 3.8.0
     */
    public boolean hasFeature(final FTPCmd feature) throws IOException {
        return hasFeature(feature.name());
    }

    /**
     * Queries the server for a supported feature.
     * Caches the parsed response to avoid resending the command repeatedly.
     *
     * @param feature the name of the feature; it is converted to upper case.
     * @return {@code true} if the feature is present, {@code false} if the feature is not present
     * or the {@link #feat()} command failed. Check {@link #getReplyCode()} or {@link #getReplyString()}
     * if it is necessary to distinguish these cases.
     *
     * @throws IOException on error
     * @since 3.0
     */
    public boolean hasFeature(final String feature) throws IOException {
        if (!initFeatureMap()) {
            return false;
        }
        return featuresMap.containsKey(feature.toUpperCase(Locale.ENGLISH));
    }

    /**
     * Queries the server for a supported feature with particular value,
     * for example "AUTH SSL" or "AUTH TLS".
     * Caches the parsed response to avoid resending the command repeatedly.
     *
     * @param feature the name of the feature; it is converted to upper case.
     * @param value the value to find.
     *
     * @return {@code true} if the feature is present, {@code false} if the feature is not present
     * or the {@link #feat()} command failed. Check {@link #getReplyCode()} or {@link #getReplyString()}
     * if it is necessary to distinguish these cases.
     *
     * @throws IOException on error
     * @since 3.0
     */
    public boolean hasFeature(final String feature, final String value) throws IOException {
        if (!initFeatureMap()) {
            return false;
        }
        final Set<String> entries = featuresMap.get(feature.toUpperCase(Locale.ENGLISH));
        if (entries != null) {
            return entries.contains(value);
        }
        return false;
    }

    private void initDefaults()
    {
        dataConnectionMode = ACTIVE_LOCAL_DATA_CONNECTION_MODE;
        passiveHost        = null;
        passivePort        = -1;
        activeExternalHost = null;
        reportActiveExternalHost = null;
        activeMinPort = 0;
        activeMaxPort = 0;
        fileType           = FTP.ASCII_FILE_TYPE;
        fileStructure      = FTP.FILE_STRUCTURE;
        fileFormat         = FTP.NON_PRINT_TEXT_FORMAT;
        fileTransferMode   = FTP.STREAM_TRANSFER_MODE;
        restartOffset      = 0;
        systemName         = null;
        entryParser        = null;
        entryParserKey    = "";
        featuresMap = null;
    }

    /*
     * Create the feature map if not already created.
     */
    private boolean initFeatureMap() throws IOException {
        if (featuresMap == null) {
            // Don't create map here, because next line may throw exception
            final int replyCode = feat();
            if (replyCode == FTPReply.NOT_LOGGED_IN) { // 503
                return false; // NET-518; don't create empy map
            }
            final boolean success = FTPReply.isPositiveCompletion(replyCode);
            // we init the map here, so we don't keep trying if we know the command will fail
            featuresMap = new HashMap<>();
            if (!success) {
                return false;
            }
            for (final String line : _replyLines) {
                if (line.startsWith(" ")) { // it's a FEAT entry
                    String key;
                    String value = "";
                    final int varsep = line.indexOf(' ', 1);
                    if (varsep > 0) {
                        key = line.substring(1, varsep);
                        value = line.substring(varsep + 1);
                    } else {
                        key = line.substring(1);
                    }
                    key = key.toUpperCase(Locale.ENGLISH);
                    Set<String> entries = featuresMap.get(key);
                    if (entries == null) {
                        entries = new HashSet<>();
                        featuresMap.put(key, entries);
                    }
                    entries.add(value);
                }
            }
        }
        return true;
    }

    /**
     * Using the default autodetect mechanism, initialize an FTPListParseEngine
     * object containing a raw file information for the current working
     * directory on the server
     * This information is obtained through the LIST command.  This object
     * is then capable of being iterated to return a sequence of FTPFile
     * objects with information filled in by the
     * <code> FTPFileEntryParser </code> used.
     * <p>
     * This method differs from using the listFiles() methods in that
     * expensive FTPFile objects are not created until needed which may be
     * an advantage on large lists.
     *
     * @return A FTPListParseEngine object that holds the raw information and
     * is capable of providing parsed FTPFile objects, one for each file
     * containing information contained in the given path in the format
     * determined by the <code> parser </code> parameter.   Null will be
     * returned if a data connection cannot be opened.  If the current working
     * directory contains no files, an empty array will be the return.
     *
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection as a result
     *                   of the client being idle or some other reason causing the server
     *                   to send FTP reply code 421.  This exception may be caught either
     *                   as an IOException or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply from the server.
     * @throws org.apache.commons.net.ftp.parser.ParserInitializationException
     *                   Thrown if the autodetect mechanism cannot
     *                   resolve the type of system we are connected with.
     * @see FTPListParseEngine
     */
    public FTPListParseEngine initiateListParsing()
    throws IOException
    {
        return initiateListParsing((String) null);
    }

    /**
     * private method through which all listFiles() and
     * initiateListParsing methods pass once a parser is determined.
     *
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection as a result
     *                   of the client being idle or some other reason causing the server
     *                   to send FTP reply code 421.  This exception may be caught either
     *                   as an IOException or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply from the server.
     * @see FTPListParseEngine
     */
    private FTPListParseEngine initiateListParsing(
            final FTPFileEntryParser parser, final String pathname)
    throws IOException
    {
        final Socket socket = _openDataConnection_(FTPCmd.LIST, getListArguments(pathname));

        final FTPListParseEngine engine = new FTPListParseEngine(parser, configuration);
        if (socket == null)
        {
            return engine;
        }

        try {
            engine.readServerList(socket.getInputStream(), getControlEncoding());
        }
        finally {
            Util.closeQuietly(socket);
        }

        completePendingCommand();
        return engine;
    }

    /**
     * Using the default autodetect mechanism, initialize an FTPListParseEngine
     * object containing a raw file information for the supplied directory.
     * This information is obtained through the LIST command.  This object
     * is then capable of being iterated to return a sequence of FTPFile
     * objects with information filled in by the
     * <code> FTPFileEntryParser </code> used.
     * <p>
     * The server may or may not expand glob expressions.  You should avoid
     * using glob expressions because the return format for glob listings
     * differs from server to server and will likely cause this method to fail.
     * <p>
     * This method differs from using the listFiles() methods in that
     * expensive FTPFile objects are not created until needed which may be
     * an advantage on large lists.
     *
     * <pre>
     *    FTPClient f=FTPClient();
     *    f.connect(server);
     *    f.login(username, password);
     *    FTPListParseEngine engine = f.initiateListParsing(directory);
     *
     *    while (engine.hasNext()) {
     *       FTPFile[] files = engine.getNext(25);  // "page size" you want
     *       //do whatever you want with these files, display them, etc.
     *       //expensive FTPFile objects not created until needed.
     *    }
     * </pre>
     * @param pathname the starting directory
     *
     * @return A FTPListParseEngine object that holds the raw information and
     * is capable of providing parsed FTPFile objects, one for each file
     * containing information contained in the given path in the format
     * determined by the <code> parser </code> parameter.   Null will be
     * returned if a data connection cannot be opened.  If the current working
     * directory contains no files, an empty array will be the return.
     *
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection as a result
     *                   of the client being idle or some other reason causing the server
     *                   to send FTP reply code 421.  This exception may be caught either
     *                   as an IOException or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply from the server.
     * @throws org.apache.commons.net.ftp.parser.ParserInitializationException
     *                   Thrown if the autodetect mechanism cannot
     *                   resolve the type of system we are connected with.
     * @see FTPListParseEngine
     */
    public FTPListParseEngine initiateListParsing(final String pathname)
    throws IOException
    {
        return initiateListParsing((String) null, pathname);
    }

    /**
     * Using the supplied parser key, initialize an FTPListParseEngine
     * object containing a raw file information for the supplied directory.
     * This information is obtained through the LIST command.  This object
     * is then capable of being iterated to return a sequence of FTPFile
     * objects with information filled in by the
     * <code> FTPFileEntryParser </code> used.
     * <p>
     * The server may or may not expand glob expressions.  You should avoid
     * using glob expressions because the return format for glob listings
     * differs from server to server and will likely cause this method to fail.
     * <p>
     * This method differs from using the listFiles() methods in that
     * expensive FTPFile objects are not created until needed which may be
     * an advantage on large lists.
     *
     * @param parserKey A string representing a designated code or fully-qualified
     * class name of an  <code> FTPFileEntryParser </code> that should be
     *               used to parse each server file listing.
     *               May be {@code null}, in which case the code checks first
     *               the system property {@link #FTP_SYSTEM_TYPE}, and if that is
     *               not defined the SYST command is used to provide the value.
     *               To allow for arbitrary system types, the return from the
     *               SYST command is used to look up an alias for the type in the
     *               {@link #SYSTEM_TYPE_PROPERTIES} properties file if it is available.
     * @param pathname the starting directory
     *
     * @return A FTPListParseEngine object that holds the raw information and
     * is capable of providing parsed FTPFile objects, one for each file
     * containing information contained in the given path in the format
     * determined by the <code> parser </code> parameter.   Null will be
     * returned if a data connection cannot be opened.  If the current working
     * directory contains no files, an empty array will be the return.
     *
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection as a result
     *                   of the client being idle or some other reason causing the server
     *                   to send FTP reply code 421.  This exception may be caught either
     *                   as an IOException or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply from the server.
     * @throws org.apache.commons.net.ftp.parser.ParserInitializationException
     *                   Thrown if the parserKey parameter cannot be
     *                   resolved by the selected parser factory.
     *                   In the DefaultFTPEntryParserFactory, this will
     *                   happen when parserKey is neither
     *                   the fully qualified class name of a class
     *                   implementing the interface
     *                   org.apache.commons.net.ftp.FTPFileEntryParser
     *                   nor a string containing one of the recognized keys
     *                   mapping to such a parser or if class loader
     *                   security issues prevent its being loaded.
     * @see FTPListParseEngine
     */
    public FTPListParseEngine initiateListParsing(
            final String parserKey, final String pathname)
    throws IOException
    {
        createParser(parserKey); // create and cache parser
        return initiateListParsing(entryParser, pathname);
    }

    /**
     * Initiate list parsing for MLSD listings in the current working directory.
     *
     * @return the engine
     * @throws IOException on error
     */
    public FTPListParseEngine initiateMListParsing() throws IOException
    {
        return initiateMListParsing(null);
    }

    /**
     * Initiate list parsing for MLSD listings.
     *
     * @param pathname the path from where to MLSD.
     * @return the engine.
     * @throws IOException on error
     */
    public FTPListParseEngine initiateMListParsing(final String pathname) throws IOException
    {
        final Socket socket = _openDataConnection_(FTPCmd.MLSD, pathname);
        final FTPListParseEngine engine = new FTPListParseEngine(MLSxEntryParser.getInstance(), configuration);
        if (socket == null)
        {
            return engine;
        }

        try {
            engine.readServerList(socket.getInputStream(), getControlEncoding());
        }
        finally {
            Util.closeQuietly(socket);
            completePendingCommand();
        }
        return engine;
    }

    /**
     * Return whether or not verification of the remote host participating
     * in data connections is enabled.  The default behavior is for
     * verification to be enabled.
     *
     * @return True if verification is enabled, false if not.
     */
    public boolean isRemoteVerificationEnabled()
    {
        return remoteVerificationEnabled;
    }

    /**
     * Whether should attempt to use EPSV with IPv4.
     * Default (if not set) is <code>false</code>
     * @return true if should attempt EPSV
     * @since 2.2
     */
    public boolean isUseEPSVwithIPv4() {
        return useEPSVwithIPv4;
    }

    /**
     * Using the default system autodetect mechanism, obtain a
     * list of directories contained in the current working directory.
     * <p>
     * This information is obtained through the LIST command.  The contents of
     * the returned array is determined by the<code> FTPFileEntryParser </code>
     * used.
     * <p>
     * N.B. the LIST command does not generally return very precise timestamps.
     * For recent files, the response usually contains hours and minutes (not seconds).
     * For older files, the output may only contain a date.
     * If the server supports it, the MLSD command returns timestamps with a precision
     * of seconds, and may include milliseconds. See {@link #mlistDir()}
     *
     * @return The list of directories contained in the current directory
     *         in the format determined by the autodetection mechanism.
     *
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection
     *                   as a result of the client being idle or some other
     *                   reason causing the server to send FTP reply code 421.
     *                   This exception may be caught either as an IOException
     *                   or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply
     *                   from the server.
     * @throws org.apache.commons.net.ftp.parser.ParserInitializationException
     *                   Thrown if the parserKey parameter cannot be
     *                   resolved by the selected parser factory.
     *                   In the DefaultFTPEntryParserFactory, this will
     *                   happen when parserKey is neither
     *                   the fully qualified class name of a class
     *                   implementing the interface
     *                   org.apache.commons.net.ftp.FTPFileEntryParser
     *                   nor a string containing one of the recognized keys
     *                   mapping to such a parser or if class loader
     *                   security issues prevent its being loaded.
     * @see org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.parser.FTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.FTPFileEntryParser
     * @since 3.0
     */
    public FTPFile[] listDirectories() throws IOException {
        return listDirectories((String) null);
    }

    /**
     * Using the default system autodetect mechanism, obtain a
     * list of directories contained in the specified directory.
     * <p>
     * This information is obtained through the LIST command.  The contents of
     * the returned array is determined by the<code> FTPFileEntryParser </code>
     * used.
     * <p>
     * N.B. the LIST command does not generally return very precise timestamps.
     * For recent files, the response usually contains hours and minutes (not seconds).
     * For older files, the output may only contain a date.
     * If the server supports it, the MLSD command returns timestamps with a precision
     * of seconds, and may include milliseconds. See {@link #mlistDir()}
     * @param parent the starting directory
     *
     * @return The list of directories contained in the specified directory
     *         in the format determined by the autodetection mechanism.
     *
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection
     *                   as a result of the client being idle or some other
     *                   reason causing the server to send FTP reply code 421.
     *                   This exception may be caught either as an IOException
     *                   or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply
     *                   from the server.
     * @throws org.apache.commons.net.ftp.parser.ParserInitializationException
     *                   Thrown if the parserKey parameter cannot be
     *                   resolved by the selected parser factory.
     *                   In the DefaultFTPEntryParserFactory, this will
     *                   happen when parserKey is neither
     *                   the fully qualified class name of a class
     *                   implementing the interface
     *                   org.apache.commons.net.ftp.FTPFileEntryParser
     *                   nor a string containing one of the recognized keys
     *                   mapping to such a parser or if class loader
     *                   security issues prevent its being loaded.
     * @see org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.parser.FTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.FTPFileEntryParser
     * @since 3.0
     */
    public FTPFile[] listDirectories(final String parent) throws IOException {
        return listFiles(parent, FTPFileFilters.DIRECTORIES);
    }

    /**
     * Using the default system autodetect mechanism, obtain a
     * list of file information for the current working directory.
     * <p>
     * This information is obtained through the LIST command.  The contents of
     * the returned array is determined by the<code> FTPFileEntryParser </code>
     * used.
     * <p>
     * N.B. the LIST command does not generally return very precise timestamps.
     * For recent files, the response usually contains hours and minutes (not seconds).
     * For older files, the output may only contain a date.
     * If the server supports it, the MLSD command returns timestamps with a precision
     * of seconds, and may include milliseconds. See {@link #mlistDir()}
     *
     * @return The list of file information contained in the current directory
     *         in the format determined by the autodetection mechanism.
     *         <p><b>
     *         NOTE:</b> This array may contain null members if any of the
     *         individual file listings failed to parse.  The caller should
     *         check each entry for null before referencing it.
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection
     *                   as a result of the client being idle or some other
     *                   reason causing the server to send FTP reply code 421.
     *                   This exception may be caught either as an IOException
     *                   or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply
     *                   from the server.
     * @throws org.apache.commons.net.ftp.parser.ParserInitializationException
     *                   Thrown if the parserKey parameter cannot be
     *                   resolved by the selected parser factory.
     *                   In the DefaultFTPEntryParserFactory, this will
     *                   happen when parserKey is neither
     *                   the fully qualified class name of a class
     *                   implementing the interface
     *                   org.apache.commons.net.ftp.FTPFileEntryParser
     *                   nor a string containing one of the recognized keys
     *                   mapping to such a parser or if class loader
     *                   security issues prevent its being loaded.
     * @see org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.parser.FTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.FTPFileEntryParser
     */
    public FTPFile[] listFiles()
    throws IOException
    {
        return listFiles((String) null);
    }

    /**
     * Using the default system autodetect mechanism, obtain a
     * list of file information for the current working directory
     * or for just a single file.
     * <p>
     * This information is obtained through the LIST command.  The contents of
     * the returned array is determined by the<code> FTPFileEntryParser </code>
     * used.
     * <p>
     * N.B. the LIST command does not generally return very precise timestamps.
     * For recent files, the response usually contains hours and minutes (not seconds).
     * For older files, the output may only contain a date.
     * If the server supports it, the MLSD command returns timestamps with a precision
     * of seconds, and may include milliseconds. See {@link #mlistDir()}
     *
     * @param pathname  The file or directory to list.  Since the server may
     *                  or may not expand glob expressions, using them here
     *                  is not recommended and may well cause this method to
     *                  fail.
     *                  Also, some servers treat a leading '-' as being an option.
     *                  To avoid this interpretation, use an absolute pathname
     *                  or prefix the pathname with ./ (unix style servers).
     *                  Some servers may support "--" as meaning end of options,
     *                  in which case "-- -xyz" should work.
     *
     * @return The list of file information contained in the given path in
     *         the format determined by the autodetection mechanism
     * @throws FTPConnectionClosedException
     *                   If the FTP server prematurely closes the connection
     *                   as a result of the client being idle or some other
     *                   reason causing the server to send FTP reply code 421.
     *                   This exception may be caught either as an IOException
     *                   or independently as itself.
     * @throws IOException
     *                   If an I/O error occurs while either sending a
     *                   command to the server or receiving a reply
     *                   from the server.
     * @throws org.apache.commons.net.ftp.parser.ParserInitializationException
     *                   Thrown if the parserKey parameter cannot be
     *                   resolved by the selected parser factory.
     *                   In the DefaultFTPEntryParserFactory, this will
     *                   happen when parserKey is neither
     *                   the fully qualified class name of a class
     *                   implementing the interface
     *                   org.apache.commons.net.ftp.FTPFileEntryParser
     *                   nor a string containing one of the recognized keys
     *                   mapping to such a parser or if class loader
     *                   security issues prevent its being loaded.
     * @see org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.parser.FTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.FTPFileEntryParser
     */
    public FTPFile[] listFiles(final String pathname) throws IOException {
        return initiateListParsing((String) null, pathname).getFiles();
    }

    /**
     * Version of {@link #listFiles(String)} which allows a filter to be provided.
     * For example: <code>listFiles("site", FTPFileFilters.DIRECTORY);</code>
     * @param pathname the initial path, may be null
     * @param filter the filter, non-null
     * @return the list of FTPFile entries.
     * @throws IOException on error
     * @since 2.2
     */
    public FTPFile[] listFiles(final String pathname, final FTPFileFilter filter) throws IOException {
        return initiateListParsing((String) null, pathname).getFiles(filter);
    }

    /**
     * Fetches the system help information from the server and returns the
     * full string.
     *
     * @return The system help string obtained from the server.  null if the
     *       information could not be obtained.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *  command to the server or receiving a reply from the server.
     */
    public String listHelp() throws IOException {
        return FTPReply.isPositiveCompletion(help()) ? getReplyString() : null;
    }

    /**
     * Fetches the help information for a given command from the server and
     * returns the full string.
     * @param command The command on which to ask for help.
     * @return The command help string obtained from the server.  null if the
     *       information could not be obtained.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *  command to the server or receiving a reply from the server.
     */
    public String listHelp(final String command) throws IOException {
        return FTPReply.isPositiveCompletion(help(command)) ? getReplyString() : null;
    }

    /**
     * Obtain a list of file names in the current working directory
     * This information is obtained through the NLST command.  If the current
     * directory contains no files, a zero length array is returned only
     * if the FTP server returned a positive completion code, otherwise,
     * null is returned (the FTP server returned a 550 error No files found.).
     * If the directory is not empty, an array of file names in the directory is
     * returned.
     *
     * @return The list of file names contained in the current working
     *     directory.  null if the list could not be obtained.
     *     If there are no file names in the directory, a zero-length array
     *     is returned.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public String[] listNames() throws IOException
    {
        return listNames(null);
    }

    /**
     * Obtain a list of file names in a directory (or just the name of a given
     * file, which is not particularly useful).  This information is obtained
     * through the NLST command.  If the given pathname is a directory and
     * contains no files,  a zero length array is returned only
     * if the FTP server returned a positive completion code, otherwise
     * null is returned (the FTP server returned a 550 error No files found.).
     * If the directory is not empty, an array of file names in the directory is
     * returned. If the pathname corresponds
     * to a file, only that file will be listed.  The server may or may not
     * expand glob expressions.
     *
     * @param pathname  The file or directory to list.
     *                  Warning: the server may treat a leading '-' as an
     *                  option introducer. If so, try using an absolute path,
     *                  or prefix the path with ./ (unix style servers).
     *                  Some servers may support "--" as meaning end of options,
     *                  in which case "-- -xyz" should work.
     * @return The list of file names contained in the given path.  null if
     *     the list could not be obtained.  If there are no file names in
     *     the directory, a zero-length array is returned.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public String[] listNames(final String pathname) throws IOException
    {
        final ArrayList<String> results = new ArrayList<>();
        try (final Socket socket = _openDataConnection_(FTPCmd.NLST, getListArguments(pathname))) {

            if (socket == null) {
                return null;
            }

            try (final BufferedReader reader = new BufferedReader(
                    new InputStreamReader(socket.getInputStream(), getControlEncoding()))) {

                String line;
                while ((line = reader.readLine()) != null) {
                    results.add(line);
                }
            }
        }

        if (completePendingCommand()) {
            return results.toArray(NetConstants.EMPTY_STRING_ARRAY);
        }

        return null;
    }

    /**
     * Login to the FTP server using the provided username and password.
     *
     * @param username The username to login under.
     * @param password The password to use.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean login(final String username, final String password) throws IOException
    {

        user(username);

        if (FTPReply.isPositiveCompletion(_replyCode)) {
            return true;
        }

        // If we get here, we either have an error code, or an intermmediate
        // reply requesting password.
        if (!FTPReply.isPositiveIntermediate(_replyCode)) {
            return false;
        }

        return FTPReply.isPositiveCompletion(pass(password));
    }

    /**
     * Login to the FTP server using the provided username, password,
     * and account.  If no account is required by the server, only
     * the username and password, the account information is not used.
     *
     * @param username The username to login under.
     * @param password The password to use.
     * @param account  The account to use.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean login(final String username, final String password, final String account)
    throws IOException
    {
        user(username);

        if (FTPReply.isPositiveCompletion(_replyCode)) {
            return true;
        }

        // If we get here, we either have an error code, or an intermmediate
        // reply requesting password.
        if (!FTPReply.isPositiveIntermediate(_replyCode)) {
            return false;
        }

        pass(password);

        if (FTPReply.isPositiveCompletion(_replyCode)) {
            return true;
        }

        if (!FTPReply.isPositiveIntermediate(_replyCode)) {
            return false;
        }

        return FTPReply.isPositiveCompletion(acct(account));
    }

    /**
     * Logout of the FTP server by sending the QUIT command.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean logout() throws IOException
    {
        return FTPReply.isPositiveCompletion(quit());
    }

    /**
     * Creates a new subdirectory on the FTP server in the current directory
     * (if a relative pathname is given) or where specified (if an absolute
     * pathname is given).
     *
     * @param pathname The pathname of the directory to create.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean makeDirectory(final String pathname) throws IOException
    {
        return FTPReply.isPositiveCompletion(mkd(pathname));
    }

    /**
     * Issue the FTP MDTM command (not supported by all servers) to retrieve the last
     * modification time of a file. The modification string should be in the
     * ISO 3077 form "YYYYMMDDhhmmss(.xxx)?". The timestamp represented should also be in
     * GMT, but not all FTP servers honor this.
     *
     * @param pathname The file path to query.
     * @return A Calendar representing the last file modification time, may be {@code null}.
     * The Calendar timestamp will be null if a parse error occurs.
     * @throws IOException if an I/O error occurs.
     * @since 3.8.0
     */
    public Calendar mdtmCalendar(final String pathname) throws IOException {
        final String modificationTime = getModificationTime(pathname);
        if (modificationTime != null) {
            return MLSxEntryParser.parseGMTdateTime(modificationTime);
        }
        return null;
    }

    /**
     * Issue the FTP MDTM command (not supported by all servers) to retrieve the last
     * modification time of a file. The modification string should be in the
     * ISO 3077 form "YYYYMMDDhhmmss(.xxx)?". The timestamp represented should also be in
     * GMT, but not all FTP servers honor this.
     *
     * @param pathname The file path to query.
     * @return A FTPFile representing the last file modification time, may be {@code null}.
     * The FTPFile timestamp will be null if a parse error occurs.
     * @throws IOException if an I/O error occurs.
     * @since 3.4
     */
    public FTPFile mdtmFile(final String pathname) throws IOException {
        final String modificationTime = getModificationTime(pathname);
        if (modificationTime != null) {
            final FTPFile file = new FTPFile();
            file.setName(pathname);
            file.setRawListing(modificationTime);
            file.setTimestamp(MLSxEntryParser.parseGMTdateTime(modificationTime));
            return file;
        }
        return null;
    }

    /**
     * Merge two copystream listeners, either or both of which may be null.
     *
     * @param local the listener used by this class, may be null
     * @return a merged listener or a single listener or null
     * @since 3.0
     */
    private CopyStreamListener mergeListeners(final CopyStreamListener local) {
        if (local == null) {
            return copyStreamListener;
        }
        if (copyStreamListener == null) {
            return local;
        }
        // Both are non-null
        final CopyStreamAdapter merged = new CopyStreamAdapter();
        merged.addCopyStreamListener(local);
        merged.addCopyStreamListener(copyStreamListener);
        return merged;
    }

    /**
     * Generate a directory listing for the current directory using the MLSD command.
     *
     * @return the array of file entries
     * @throws IOException on error
     * @since 3.0
     */
    public FTPFile[] mlistDir() throws IOException
    {
        return mlistDir(null);
    }

    /**
     * Generate a directory listing using the MLSD command.
     *
     * @param pathname the directory name, may be {@code null}
     * @return the array of file entries
     * @throws IOException on error
     * @since 3.0
     */
    public FTPFile[] mlistDir(final String pathname) throws IOException {
        return initiateMListParsing(pathname).getFiles();
    }

    /**
     * Generate a directory listing using the MLSD command.
     *
     * @param pathname the directory name, may be {@code null}
     * @param filter the filter to apply to the responses
     * @return the array of file entries
     * @throws IOException on error
     * @since 3.0
     */
    public FTPFile[] mlistDir(final String pathname, final FTPFileFilter filter) throws IOException {
        return initiateMListParsing(pathname).getFiles(filter);
    }

    /**
     * Get file details using the MLST command
     *
     * @param pathname the file or directory to list, may be {@code null}
     * @return the file details, may be {@code null}
     * @throws IOException on error
     * @since 3.0
     */
    public FTPFile mlistFile(final String pathname) throws IOException
    {
        final boolean success = FTPReply.isPositiveCompletion(sendCommand(FTPCmd.MLST, pathname));
        if (success){
            String reply = getReplyString(1);
            // some FTP server reply not contains space before fact(s)
            if(reply.charAt(0) != ' ') { reply = " " + reply; }
            /* check the response makes sense.
             * Must have space before fact(s) and between fact(s) and file name
             * Fact(s) can be absent, so at least 3 chars are needed.
             */
            if (reply.length() < 3) {
                throw new MalformedServerReplyException("Invalid server reply (MLST): '" + reply + "'");
            }
            // some FTP server reply contains more than one space before fact(s)
            final String entry = reply.replaceAll("^\\s+", ""); // skip leading space for parser
            return MLSxEntryParser.parseEntry(entry);
        }
        return null;
    }

    /**
     * Returns the pathname of the current working directory.
     *
     * @return The pathname of the current working directory.  If it cannot
     *         be obtained, returns null.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public String printWorkingDirectory() throws IOException
    {
        if (pwd() != FTPReply.PATHNAME_CREATED) {
            return null;
        }

        return parsePathname(_replyLines.get( _replyLines.size() - 1));
    }

    /**
     * Reinitialize the FTP session.  Not all FTP servers support this
     * command, which issues the FTP REIN command.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.4 (made public)
     */
    public boolean reinitialize() throws IOException
    {
        rein();

        if (FTPReply.isPositiveCompletion(_replyCode) ||
                (FTPReply.isPositivePreliminary(_replyCode) &&
                        FTPReply.isPositiveCompletion(getReply())))
        {

            initDefaults();

            return true;
        }

        return false;
    }

    // For server to server transfers
    /**
     * Initiate a server to server file transfer.  This method tells the
     * server to which the client is connected to append to a given file on
     * the other server.  The other server must have had a
     * <code> remoteRetrieve </code> issued to it by another FTPClient.
     *
     * @param fileName  The name of the file to be appended to, or if the
     *        file does not exist, the name to call the file being stored.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean remoteAppend(final String fileName) throws IOException
    {
        if (dataConnectionMode == ACTIVE_REMOTE_DATA_CONNECTION_MODE ||
                dataConnectionMode == PASSIVE_REMOTE_DATA_CONNECTION_MODE) {
            return FTPReply.isPositivePreliminary(appe(fileName));
        }
        return false;
    }

    /**
     * Initiate a server to server file transfer.  This method tells the
     * server to which the client is connected to retrieve a given file from
     * the other server.
     *
     * @param fileName  The name of the file to retrieve.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean remoteRetrieve(final String fileName) throws IOException
    {
        if (dataConnectionMode == ACTIVE_REMOTE_DATA_CONNECTION_MODE ||
                dataConnectionMode == PASSIVE_REMOTE_DATA_CONNECTION_MODE) {
            return FTPReply.isPositivePreliminary(retr(fileName));
        }
        return false;
    }

    /**
     * Initiate a server to server file transfer.  This method tells the
     * server to which the client is connected to store a file on
     * the other server using the given file name.  The other server must
     * have had a <code> remoteRetrieve </code> issued to it by another
     * FTPClient.
     *
     * @param fileName  The name to call the file that is to be stored.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean remoteStore(final String fileName) throws IOException
    {
        if (dataConnectionMode == ACTIVE_REMOTE_DATA_CONNECTION_MODE ||
                dataConnectionMode == PASSIVE_REMOTE_DATA_CONNECTION_MODE) {
            return FTPReply.isPositivePreliminary(stor(fileName));
        }
        return false;
    }

    /**
     * Initiate a server to server file transfer.  This method tells the
     * server to which the client is connected to store a file on
     * the other server using a unique file name.
     * The other server must have had a <code> remoteRetrieve </code> issued
     * to it by another FTPClient.  Many FTP servers require that a base
     * file name be given from which the unique file name can be derived.  For
     * those servers use the other version of <code> remoteStoreUnique</code>
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean remoteStoreUnique() throws IOException
    {
        if (dataConnectionMode == ACTIVE_REMOTE_DATA_CONNECTION_MODE ||
                dataConnectionMode == PASSIVE_REMOTE_DATA_CONNECTION_MODE) {
            return FTPReply.isPositivePreliminary(stou());
        }
        return false;
    }

    /**
     * Initiate a server to server file transfer.  This method tells the
     * server to which the client is connected to store a file on
     * the other server using a unique file name based on the given file name.
     * The other server must have had a <code> remoteRetrieve </code> issued
     * to it by another FTPClient.
     *
     * @param fileName  The name on which to base the file name of the file
     *                  that is to be stored.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean remoteStoreUnique(final String fileName) throws IOException
    {
        if (dataConnectionMode == ACTIVE_REMOTE_DATA_CONNECTION_MODE ||
                dataConnectionMode == PASSIVE_REMOTE_DATA_CONNECTION_MODE) {
            return FTPReply.isPositivePreliminary(stou(fileName));
        }
        return false;
    }

    /**
     * Removes a directory on the FTP server (if empty).
     *
     * @param pathname  The pathname of the directory to remove.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean removeDirectory(final String pathname) throws IOException
    {
        return FTPReply.isPositiveCompletion(rmd(pathname));
    }

    /**
     * Renames a remote file.
     *
     * @param from  The name of the remote file to rename.
     * @param to    The new name of the remote file.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean rename(final String from, final String to) throws IOException
    {
        if (!FTPReply.isPositiveIntermediate(rnfr(from))) {
            return false;
        }

        return FTPReply.isPositiveCompletion(rnto(to));
    }

    /**
     * Restart a <code>STREAM_TRANSFER_MODE</code> file transfer starting
     * from the given offset.  This will only work on FTP servers supporting
     * the REST comand for the stream transfer mode.  However, most FTP
     * servers support this.  Any subsequent file transfer will start
     * reading or writing the remote file from the indicated offset.
     *
     * @param offset  The offset into the remote file at which to start the
     *           next file transfer.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     * @since 3.1 (changed from private to protected)
     */
    protected boolean restart(final long offset) throws IOException
    {
        restartOffset = 0;
        return FTPReply.isPositiveIntermediate(rest(Long.toString(offset)));
    }

    /**
     * Retrieves a named file from the server and writes it to the given
     * OutputStream.  This method does NOT close the given OutputStream.
     * If the current file type is ASCII, line separators in the file are
     * converted to the local representation.
     * <p>
     * Note: if you have used {@link #setRestartOffset(long)},
     * the file data will start from the selected offset.
     * @param remote  The name of the remote file.
     * @param local   The local OutputStream to which to write the file.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws org.apache.commons.net.io.CopyStreamException
     *      If an I/O error occurs while actually
     *      transferring the file.  The CopyStreamException allows you to
     *      determine the number of bytes transferred and the IOException
     *      causing the error.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean retrieveFile(final String remote, final OutputStream local)
    throws IOException
    {
        return _retrieveFile(FTPCmd.RETR.getCommand(), remote, local);
    }

    /**
     * Returns an InputStream from which a named file from the server
     * can be read.  If the current file type is ASCII, the returned
     * InputStream will convert line separators in the file to
     * the local representation.  You must close the InputStream when you
     * finish reading from it.  The InputStream itself will take care of
     * closing the parent data connection socket upon being closed.
     * <p>
     * <b>To finalize the file transfer you must call
     * {@link #completePendingCommand  completePendingCommand } and
     * check its return value to verify success.</b>
     * If this is not done, subsequent commands may behave unexpectedly.
     * <p>
     * Note: if you have used {@link #setRestartOffset(long)},
     * the file data will start from the selected offset.
     *
     * @param remote  The name of the remote file.
     * @return An InputStream from which the remote file can be read.  If
     *      the data connection cannot be opened (e.g., the file does not
     *      exist), null is returned (in which case you may check the reply
     *      code to determine the exact reason for failure).
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public InputStream retrieveFileStream(final String remote) throws IOException
    {
        return _retrieveFileStream(FTPCmd.RETR.getCommand(), remote);
    }


    /**
     * Sends a NOOP command to the FTP server.  This is useful for preventing
     * server timeouts.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean sendNoOp() throws IOException
    {
        return FTPReply.isPositiveCompletion(noop());
    }

    /**
     * Send a site specific command.
     * @param arguments The site specific command and arguments.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean sendSiteCommand(final String arguments) throws IOException
    {
        return FTPReply.isPositiveCompletion(site(arguments));
    }

    /**
     * Set the external IP address in active mode.
     * Useful when there are multiple network cards.
     *
     * @param ipAddress The external IP address of this machine.
     * @throws UnknownHostException if the ipAddress cannot be resolved
     * @since 2.2
     */
    public void setActiveExternalIPAddress(final String ipAddress) throws UnknownHostException
    {
        this.activeExternalHost = InetAddress.getByName(ipAddress);
    }

    /**
     * Set the client side port range in active mode.
     *
     * @param minPort The lowest available port (inclusive).
     * @param maxPort The highest available port (inclusive).
     * @since 2.2
     */
    public void setActivePortRange(final int minPort, final int maxPort)
    {
        this.activeMinPort = minPort;
        this.activeMaxPort = maxPort;
    }

    /**
     * Enables or disables automatic server encoding detection (only UTF-8 supported).
     * <p>
     * Does not affect existing connections; must be invoked before a connection is established.
     *
     * @param autodetect If true, automatic server encoding detection will be enabled.
     */
    public void setAutodetectUTF8(final boolean autodetect)
    {
        autodetectEncoding = autodetect;
    }

    /**
     * Set the internal buffer size for buffered data streams.
     *
     * @param bufSize The size of the buffer. Use a non-positive value to use the default.
     */
    public void setBufferSize(final int bufSize) {
        bufferSize = bufSize;
    }

    /**
     * Sets how long to wait for control keep-alive message replies.
     *
     * @param timeoutMillis number of milliseconds to wait (defaults to 1000)
     * @since 3.0
     * @see #setControlKeepAliveTimeout(long)
     */
    public void setControlKeepAliveReplyTimeout(final int timeoutMillis) {
        controlKeepAliveReplyTimeoutMillis = timeoutMillis;
    }

    /**
     * Set the time to wait between sending control connection keepalive messages
     * when processing file upload or download.
     * <p>
     * See the class Javadoc section "Control channel keep-alive feature:"
     *
     * @param controlIdleSeconds the wait (in seconds) between keepalive messages. Zero (or less) disables.
     * @since 3.0
     * @see #setControlKeepAliveReplyTimeout(int)
     */
    public void setControlKeepAliveTimeout(final long controlIdleSeconds){
        controlKeepAliveTimeoutMillis = controlIdleSeconds * 1000;
    }

    /**
     * Set the listener to be used when performing store/retrieve operations.
     * The default value (if not set) is {@code null}.
     *
     * @param listener to be used, may be {@code null} to disable
     * @since 3.0
     */
    public void setCopyStreamListener(final CopyStreamListener listener){
        copyStreamListener = listener;
    }

    /**
     * Sets the timeout in milliseconds to use when reading from the
     * data connection.  This timeout will be set immediately after
     * opening the data connection, provided that the value is &ge; 0.
     * <p>
     * <b>Note:</b> the timeout will also be applied when calling accept()
     * whilst establishing an active local data connection.
     * @param  timeoutMillis The default timeout in milliseconds that is used when
     *        opening a data connection socket. The value 0 means an infinite timeout.
     */
    public void setDataTimeout(final int timeoutMillis)
    {
        dataTimeoutMillis = timeoutMillis;
    }

    /**
     * Sets the file structure.  The default structure is
     * <code> FTP.FILE_STRUCTURE </code> if this method is never called
     * or if a connect method is called.
     *
     * @param structure  The structure of the file (one of the FTP class
     *         <code>_STRUCTURE</code> constants).
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean setFileStructure(final int structure) throws IOException
    {
        if (FTPReply.isPositiveCompletion(stru(structure)))
        {
            fileStructure = structure;
            return true;
        }
        return false;
    }

    /**
     * Sets the transfer mode.  The default transfer mode
     * <code> FTP.STREAM_TRANSFER_MODE </code> if this method is never called
     * or if a connect method is called.
     *
     * @param mode  The new transfer mode to use (one of the FTP class
     *         <code>_TRANSFER_MODE</code> constants).
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean setFileTransferMode(final int mode) throws IOException
    {
        if (FTPReply.isPositiveCompletion(mode(mode)))
        {
            fileTransferMode = mode;
            return true;
        }
        return false;
    }

    /**
     * Sets the file type to be transferred.  This should be one of
     * <code> FTP.ASCII_FILE_TYPE </code>, <code> FTP.BINARY_FILE_TYPE</code>,
     * etc.  The file type only needs to be set when you want to change the
     * type.  After changing it, the new type stays in effect until you change
     * it again.  The default file type is <code> FTP.ASCII_FILE_TYPE </code>
     * if this method is never called.
     * <br>
     * The server default is supposed to be ASCII (see RFC 959), however many
     * ftp servers default to BINARY. <b>To ensure correct operation with all servers,
     * always specify the appropriate file type after connecting to the server.</b>
     * <br>
     * <p>
     * <b>N.B.</b> currently calling any connect method will reset the type to
     * FTP.ASCII_FILE_TYPE.
     * @param fileType The <code> _FILE_TYPE </code> constant indicating the
     *                 type of file.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean setFileType(final int fileType) throws IOException
    {
        if (FTPReply.isPositiveCompletion(type(fileType)))
        {
            this.fileType = fileType;
            this.fileFormat = FTP.NON_PRINT_TEXT_FORMAT;
            return true;
        }
        return false;
    }

    /**
     * Sets the file type to be transferred and the format.  The type should be
     * one of  <code> FTP.ASCII_FILE_TYPE </code>,
     * <code> FTP.BINARY_FILE_TYPE </code>, etc.  The file type only needs to
     * be set when you want to change the type.  After changing it, the new
     * type stays in effect until you change it again.  The default file type
     * is <code> FTP.ASCII_FILE_TYPE </code> if this method is never called.
     * <br>
     * The server default is supposed to be ASCII (see RFC 959), however many
     * ftp servers default to BINARY. <b>To ensure correct operation with all servers,
     * always specify the appropriate file type after connecting to the server.</b>
     * <br>
     * The format should be one of the FTP class <code> TEXT_FORMAT </code>
     * constants, or if the type is <code> FTP.LOCAL_FILE_TYPE </code>, the
     * format should be the byte size for that type.  The default format
     * is <code> FTP.NON_PRINT_TEXT_FORMAT </code> if this method is never
     * called.
     * <p>
     * <b>N.B.</b> currently calling any connect method will reset the type to
     * FTP.ASCII_FILE_TYPE and the formatOrByteSize to FTP.NON_PRINT_TEXT_FORMAT.
     *
     * @param fileType The <code> _FILE_TYPE </code> constant indicating the
     *                 type of file.
     * @param formatOrByteSize  The format of the file (one of the
     *              <code>_FORMAT</code> constants.  In the case of
     *              <code>LOCAL_FILE_TYPE</code>, the byte size.
     *
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean setFileType(final int fileType, final int formatOrByteSize)
    throws IOException
    {
        if (FTPReply.isPositiveCompletion(type(fileType, formatOrByteSize)))
        {
            this.fileType = fileType;
            this.fileFormat = formatOrByteSize;
            return true;
        }
        return false;
    }

    /**
     * You can set this to true if you would like to get hidden files when {@link #listFiles} too.
     * A <code>LIST -a</code> will be issued to the ftp server.
     * It depends on your ftp server if you need to call this method, also dont expect to get rid
     * of hidden files if you call this method with "false".
     *
     * @param listHiddenFiles true if hidden files should be listed
     * @since 2.0
     */
    public void setListHiddenFiles(final boolean listHiddenFiles) {
        this.listHiddenFiles = listHiddenFiles;
    }

    /**
     * Issue the FTP MFMT command (not supported by all servers) which sets the last
     * modified time of a file.
     *
     * The timestamp should be in the form <code>YYYYMMDDhhmmss</code>. It should also
     * be in GMT, but not all servers honor this.
     *
     * An FTP server would indicate its support of this feature by including "MFMT"
     * in its response to the FEAT command, which may be retrieved by FTPClient.features()
     *
     * @param pathname The file path for which last modified time is to be changed.
     * @param timeval The timestamp to set to, in <code>YYYYMMDDhhmmss</code> format.
     * @return true if successfully set, false if not
     * @throws IOException if an I/O error occurs.
     * @since 2.2
     * @see <a href="http://tools.ietf.org/html/draft-somers-ftp-mfxx-04">http://tools.ietf.org/html/draft-somers-ftp-mfxx-04</a>
     */
    public boolean setModificationTime(final String pathname, final String timeval) throws IOException {
        return (FTPReply.isPositiveCompletion(mfmt(pathname, timeval)));
    }

    /**
     * set the factory used for parser creation to the supplied factory object.
     *
     * @param parserFactory
     *               factory object used to create FTPFileEntryParsers
     *
     * @see org.apache.commons.net.ftp.parser.FTPFileEntryParserFactory
     * @see org.apache.commons.net.ftp.parser.DefaultFTPFileEntryParserFactory
     */
    public void setParserFactory(final FTPFileEntryParserFactory parserFactory) {
        this.parserFactory = parserFactory;
    }

    /**
     * Set the local IP address to use in passive mode.
     * Useful when there are multiple network cards.
     *
     * @param inetAddress The local IP address of this machine.
     */
    public void setPassiveLocalIPAddress(final InetAddress inetAddress)
    {
        this.passiveLocalHost = inetAddress;
    }

    /**
     * Set the local IP address to use in passive mode.
     * Useful when there are multiple network cards.
     *
     * @param ipAddress The local IP address of this machine.
     * @throws UnknownHostException if the ipAddress cannot be resolved
     */
    public void setPassiveLocalIPAddress(final String ipAddress) throws UnknownHostException
    {
        this.passiveLocalHost = InetAddress.getByName(ipAddress);
    }

    /**
     * Enables or disables passive mode NAT workaround.
     * If enabled, a site-local PASV mode reply address will be replaced with the
     * remote host address to which the PASV mode request was sent
     * (unless that is also a site local address).
     * This gets around the problem that some NAT boxes may change the
     * reply.
     *
     * The default is true, i.e. site-local replies are replaced.
     * @param enabled true to enable replacing internal IP's in passive
     * mode.
     * @deprecated (3.6) use {@link #setPassiveNatWorkaroundStrategy(HostnameResolver)} instead
     */
    @Deprecated
    public void setPassiveNatWorkaround(final boolean enabled) {
        if (enabled) {
            this.passiveNatWorkaroundStrategy = new NatServerResolverImpl(this);
        } else {
            this.passiveNatWorkaroundStrategy = null;
        }
    }

    /**
     * Set the workaround strategy to replace the PASV mode reply addresses.
     * This gets around the problem that some NAT boxes may change the reply.
     *
     * The default implementation is {@code NatServerResolverImpl}, i.e. site-local
     * replies are replaced.
     * @param resolver strategy to replace internal IP's in passive mode
     * or null to disable the workaround (i.e. use PASV mode reply address.)
     * @since 3.6
     */
    public void setPassiveNatWorkaroundStrategy(final HostnameResolver resolver) {
        this.passiveNatWorkaroundStrategy = resolver;
    }

    /**
     * Sets the value to be used for the data socket SO_RCVBUF option.
     * If the value is positive, the option will be set when the data socket has been created.
     *
     * @param bufSize The size of the buffer, zero or negative means the value is ignored.
     * @since 3.3
     */
    public void setReceieveDataSocketBufferSize(final int bufSize) {
        receiveDataSocketBufferSize = bufSize;
    }

    /**
     * Enable or disable verification that the remote host taking part
     * of a data connection is the same as the host to which the control
     * connection is attached.  The default is for verification to be
     * enabled.  You may set this value at any time, whether the
     * FTPClient is currently connected or not.
     *
     * @param enable True to enable verification, false to disable verification.
     */
    public void setRemoteVerificationEnabled(final boolean enable)
    {
        remoteVerificationEnabled = enable;
    }

    /**
     * Set the external IP address to report in EPRT/PORT commands in active mode.
     * Useful when there are multiple network cards.
     *
     * @param ipAddress The external IP address of this machine.
     * @throws UnknownHostException if the ipAddress cannot be resolved
     * @since 3.1
     * @see #getReportHostAddress()
     */
    public void setReportActiveExternalIPAddress(final String ipAddress) throws UnknownHostException
    {
        this.reportActiveExternalHost = InetAddress.getByName(ipAddress);
    }

    /**
     * Sets the restart offset for file transfers.
     * <p>
     * The restart command is not sent to the server immediately.
     * It is sent when a data connection is created as part of a
     * subsequent command.
     * The restart marker is reset to zero after use.
     * </p>
     * <p>
     * <b>Note: This method should only be invoked immediately prior to
     * the transfer to which it applies.</b>
     *
     * @param offset  The offset into the remote file at which to start the
     *           next file transfer.  This must be a value greater than or
     *           equal to zero.
     */
    public void setRestartOffset(final long offset)
    {
        if (offset >= 0) {
            restartOffset = offset;
        }
    }

    /**
     * Sets the value to be used for the data socket SO_SNDBUF option.
     * If the value is positive, the option will be set when the data socket has been created.
     *
     * @param bufSize The size of the buffer, zero or negative means the value is ignored.
      * @since 3.3
    */
    public void setSendDataSocketBufferSize(final int bufSize) {
        sendDataSocketBufferSize = bufSize;
    }

    /**
     * Set whether to use EPSV with IPv4.
     * Might be worth enabling in some circumstances.
     *
     * For example, when using IPv4 with NAT it
     * may work with some rare configurations.
     * E.g. if FTP server has a static PASV address (external network)
     * and the client is coming from another internal network.
     * In that case the data connection after PASV command would fail,
     * while EPSV would make the client succeed by taking just the port.
     *
     * @param selected value to set.
     * @since 2.2
     */
    public void setUseEPSVwithIPv4(final boolean selected) {
        this.useEPSVwithIPv4 = selected;
    }

    private boolean storeFile(final FTPCmd command, final String remote, final InputStream local)
    throws IOException
    {
        return _storeFile(command.getCommand(), remote, local);
    }

    /**
     * Stores a file on the server using the given name and taking input
     * from the given InputStream.  This method does NOT close the given
     * InputStream.  If the current file type is ASCII, line separators in
     * the file are transparently converted to the NETASCII format (i.e.,
     * you should not attempt to create a special InputStream to do this).
     *
     * @param remote  The name to give the remote file.
     * @param local   The local InputStream from which to read the file.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws org.apache.commons.net.io.CopyStreamException
     *      If an I/O error occurs while actually
     *      transferring the file.  The CopyStreamException allows you to
     *      determine the number of bytes transferred and the IOException
     *      causing the error.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean storeFile(final String remote, final InputStream local)
    throws IOException
    {
        return storeFile(FTPCmd.STOR, remote, local);
    }

    private OutputStream storeFileStream(final FTPCmd command, final String remote)
    throws IOException
    {
        return _storeFileStream(command.getCommand(), remote);
    }

    /**
     * Returns an OutputStream through which data can be written to store
     * a file on the server using the given name.  If the current file type
     * is ASCII, the returned OutputStream will convert line separators in
     * the file to the NETASCII format  (i.e., you should not attempt to
     * create a special OutputStream to do this).  You must close the
     * OutputStream when you finish writing to it.  The OutputStream itself
     * will take care of closing the parent data connection socket upon being
     * closed.
     * <p>
     * <b>To finalize the file transfer you must call
     * {@link #completePendingCommand  completePendingCommand } and
     * check its return value to verify success.</b>
     * If this is not done, subsequent commands may behave unexpectedly.
     *
     * @param remote  The name to give the remote file.
     * @return An OutputStream through which the remote file can be written.  If
     *      the data connection cannot be opened (e.g., the file does not
     *      exist), null is returned (in which case you may check the reply
     *      code to determine the exact reason for failure).
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public OutputStream storeFileStream(final String remote) throws IOException
    {
        return storeFileStream(FTPCmd.STOR, remote);
    }

    /**
     * Stores a file on the server using a unique name assigned by the
     * server and taking input from the given InputStream.  This method does
     * NOT close the given
     * InputStream.  If the current file type is ASCII, line separators in
     * the file are transparently converted to the NETASCII format (i.e.,
     * you should not attempt to create a special InputStream to do this).
     *
     * @param local   The local InputStream from which to read the file.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws org.apache.commons.net.io.CopyStreamException
     *      If an I/O error occurs while actually
     *      transferring the file.  The CopyStreamException allows you to
     *      determine the number of bytes transferred and the IOException
     *      causing the error.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean storeUniqueFile(final InputStream local) throws IOException
    {
        return storeFile(FTPCmd.STOU, null, local);
    }

    /**
     * Stores a file on the server using a unique name derived from the
     * given name and taking input
     * from the given InputStream.  This method does NOT close the given
     * InputStream.  If the current file type is ASCII, line separators in
     * the file are transparently converted to the NETASCII format (i.e.,
     * you should not attempt to create a special InputStream to do this).
     *
     * @param remote  The name on which to base the unique name given to
     *                the remote file.
     * @param local   The local InputStream from which to read the file.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws org.apache.commons.net.io.CopyStreamException
     *      If an I/O error occurs while actually
     *      transferring the file.  The CopyStreamException allows you to
     *      determine the number of bytes transferred and the IOException
     *      causing the error.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean storeUniqueFile(final String remote, final InputStream local)
    throws IOException
    {
        return storeFile(FTPCmd.STOU, remote, local);
    }

    /**
     * Returns an OutputStream through which data can be written to store
     * a file on the server using a unique name assigned by the server.
     * If the current file type
     * is ASCII, the returned OutputStream will convert line separators in
     * the file to the NETASCII format  (i.e., you should not attempt to
     * create a special OutputStream to do this).  You must close the
     * OutputStream when you finish writing to it.  The OutputStream itself
     * will take care of closing the parent data connection socket upon being
     * closed.
     * <p>
     * <b>To finalize the file transfer you must call
     * {@link #completePendingCommand  completePendingCommand } and
     * check its return value to verify success.</b>
     * If this is not done, subsequent commands may behave unexpectedly.
     *
     * @return An OutputStream through which the remote file can be written.  If
     *      the data connection cannot be opened (e.g., the file does not
     *      exist), null is returned (in which case you may check the reply
     *      code to determine the exact reason for failure).
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public OutputStream storeUniqueFileStream() throws IOException
    {
        return storeFileStream(FTPCmd.STOU, null);
    }

    /**
     * Returns an OutputStream through which data can be written to store
     * a file on the server using a unique name derived from the given name.
     * If the current file type
     * is ASCII, the returned OutputStream will convert line separators in
     * the file to the NETASCII format  (i.e., you should not attempt to
     * create a special OutputStream to do this).  You must close the
     * OutputStream when you finish writing to it.  The OutputStream itself
     * will take care of closing the parent data connection socket upon being
     * closed.
     * <p>
     * <b>To finalize the file transfer you must call
     * {@link #completePendingCommand  completePendingCommand } and
     * check its return value to verify success.</b>
     * If this is not done, subsequent commands may behave unexpectedly.
     *
     * @param remote  The name on which to base the unique name given to
     *                the remote file.
     * @return An OutputStream through which the remote file can be written.  If
     *      the data connection cannot be opened (e.g., the file does not
     *      exist), null is returned (in which case you may check the reply
     *      code to determine the exact reason for failure).
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public OutputStream storeUniqueFileStream(final String remote) throws IOException
    {
        return storeFileStream(FTPCmd.STOU, remote);
    }

    /**
     * Issue the FTP SMNT command.
     *
     * @param pathname The pathname to mount.
     * @return True if successfully completed, false if not.
     * @throws FTPConnectionClosedException
     *      If the FTP server prematurely closes the connection as a result
     *      of the client being idle or some other reason causing the server
     *      to send FTP reply code 421.  This exception may be caught either
     *      as an IOException or independently as itself.
     * @throws IOException  If an I/O error occurs while either sending a
     *      command to the server or receiving a reply from the server.
     */
    public boolean structureMount(final String pathname) throws IOException
    {
        return FTPReply.isPositiveCompletion(smnt(pathname));
    }
}

org/apache/commons/net/ftp/FTPClient.java

 

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