public FTPControlSocket(String remoteHost) throws IOException, FTPException 
{
                                 
         this(remoteHost, CONTROL_PORT);
}

Constructor. Performs TCP connection and sets up reader/writer

Parameters:

remoteHost - Remote hostname

 public FTPControlSocket(InetAddress remoteAddr) throws IOException, FTPException 
{
         this(remoteAddr, CONTROL_PORT);
}

Constructor. Performs TCP connection and sets up reader/writer

Parameters:

remoteAddr - Remote inet address

 public FTPControlSocket(String remoteHost,
    int controlPort) throws IOException, FTPException 
{
         controlSock = new Socket(remoteHost, controlPort);
         initStreams();
         validateConnection();
}

Constructor. Performs TCP connection and sets up reader/writer. Allows different control port to be used

Parameters:

remoteHost - Remote hostname

controlPort - port for control stream

 public FTPControlSocket(InetAddress remoteAddr,
    int controlPort) throws IOException, FTPException 
{
         controlSock = new Socket(remoteAddr, controlPort);
         initStreams();
         validateConnection();
}

Constructor. Performs TCP connection and sets up reader/writer. Allows different control port to be used

Parameters:

remoteAddr - Remote inet address

controlPort - port for control stream

 FTPDataSocket createDataSocket(FTPConnectMode connectMode) throws IOException, FTPException 
{
        if (connectMode == FTPConnectMode.ACTIVE) {
            return new FTPDataSocket(createDataSocketActive());
        }
        else { // PASV
            return new FTPDataSocket(createDataSocketPASV());
        }
}

Request a data socket be created on the server, connect to it and return our connected socket.

 ServerSocket createDataSocketActive() throws IOException, FTPException 
{
        // use any available port
        ServerSocket socket = new ServerSocket(0);
        // get the local address to which the control socket is bound.
        InetAddress localhost =  controlSock.getLocalAddress();
        // send the PORT command to the server
        setDataPort(localhost, (short)socket.getLocalPort());
        return socket;
}

Request a data socket be created on the Client client on any free port, do not connect it to yet.

 Socket createDataSocketPASV() throws IOException, FTPException 
{
         // PASSIVE command - tells the server to listen for
         // a connection attempt rather than initiating it
         String reply = sendCommand("PASV");
         validateReply(reply, "227");
         // The reply to PASV is in the form:
         // 227 Entering Passive Mode (h1,h2,h3,h4,p1,p2).
         // where h1..h4 are the IP address to connect and
         // p1,p2 the port number
         // Example:
         // 227 Entering Passive Mode (128,3,122,1,15,87).
         // extract the IP data string from between the brackets
         int bracket1 = reply.indexOf('(");
         int bracket2 = reply.indexOf(')");
         String ipData = reply.substring(bracket1+1,bracket2);
         int parts[] = new int[6];
         int len = ipData.length();
         int partCount = 0;
         StringBuffer buf = new StringBuffer();
         // loop thru and examine each char
         for (int i = 0; i <  len && partCount < = 6; i++) {
             char ch = ipData.charAt(i);
             if (Character.isDigit(ch))
                 buf.append(ch);
             else if (ch != ',") {
                 throw new FTPException("Malformed PASV reply: " + reply);
             }
             // get the part
             if (ch == '," || i+1 == len) { // at end or at separator
                 try {
                     parts[partCount++] = Integer.parseInt(buf.toString());
                     buf.setLength(0);
                 }
                 catch (NumberFormatException ex) {
                     throw new FTPException("Malformed PASV reply: " + reply);
                 }
             }
         }
         // assemble the IP address
         // we try connecting, so we don't bother checking digits etc
         String ipAddress = parts[0] + "."+ parts[1]+ "." +
             parts[2] + "." + parts[3];
         // assemble the port number
         int port = (parts[4] < <  8) + parts[5];
         // create the socket
         return new Socket(ipAddress, port);
}

Request a data socket be created on the server, connect to it and return our connected socket.

  void debugResponses(boolean on) 
{
         debugResponses = on;
}

Switch debug of responses on or off

 String getRemoteHostName() 
{
         InetAddress addr = controlSock.getInetAddress();
         return addr.getHostName();
}

Get the name of the remote host

 public  void logout() throws IOException 
{
         writer.close();
         reader.close();
         controlSock.close();
}

Quit this FTP session and clean up.

 String readReply() throws IOException 
{
         StringBuffer reply = new StringBuffer(reader.readLine());
         if (debugResponses)
             System.out.println(reply.toString());
         String replyCode = reply.toString().substring(0, 3);
         // check for multiline response and build up
         // the reply
         if (reply.charAt(3) == '-") {
             boolean complete = false;
             while (!complete) {
                 String line = reader.readLine();
                 if (debugResponses)
                     System.out.println(line);
                 if (line.length()  > 3 &&
                     line.substring(0, 3).equals(replyCode) &&
                     line.charAt(3) == ' ") {
                     reply.append(line.substring(3));
                     complete = true;
                 }
                 else { // not the last line
                     reply.append(" ");
                     reply.append(line);
                 }
             } // end while
         } // end if
         return reply.toString();
}

Read the FTP server's reply to a previously issued command. RFC 959 states that a reply consists of the 3 digit code followed by text. The 3 digit code is followed by a hyphen if it is a muliline response, and the last line starts with the same 3 digit code.

 String sendCommand(String command) throws IOException 
{
         if (debugResponses)
             System.out.println("--- > " + command);
         // send it
         writer.write(command + EOL);
         writer.flush();
         // and read the result
         return readReply();
}

Send a command to the FTP server and return the server's reply

  void setTimeout(int millis) throws IOException 
{
        if (controlSock == null)
            throw new IllegalStateException(
                        "Failed to set timeout - no control socket");
        controlSock.setSoTimeout(millis);
}

Set the TCP timeout on the underlying control socket. If a timeout is set, then any operation which takes longer than the timeout value will be killed with a java.io.InterruptedException.

 protected byte[] toByteArray(short value) 
{
        byte[] bytes = new byte[2];
        bytes[0] = (byte) (value  > > 8);     // bits 1- 8
        bytes[1] = (byte) (value & 0x00FF); // bits 9-16
        return bytes;
}

Convert a short into a byte array

  void validateReply(String reply,
    String expectedReplyCode) throws IOException, FTPException 
{
         // all reply codes are 3 chars long
         String replyCode = reply.substring(0, 3);
         // if unexpected reply, throw an exception
         if (!replyCode.equals(expectedReplyCode)) {
             throw new FTPException(reply.substring(4), replyCode);
         }
}

Validate the response the host has supplied against the expected reply. If we get an unexpected reply we throw an exception, setting the message to that returned by the FTP server

  void validateReply(String reply,
    String[] expectedReplyCodes) throws IOException, FTPException 
{
         // all reply codes are 3 chars long
         String replyCode = reply.substring(0, 3);
         for (int i = 0; i <  expectedReplyCodes.length; i++)
             if (replyCode.equals(expectedReplyCodes[i]))
                 return;
         // got this far, not recognised
         throw new FTPException(reply.substring(4), replyCode);
}

Validate the response the host has supplied against the expected reply. If we get an unexpected reply we throw an exception, setting the message to that returned by the FTP server