/*

  * Copyright 2008 the original author or authors.

  * 

  * Licensed under the Apache License, Version 2.0 (the "License");

  * you may not use this file except in compliance with the License.

  * You may obtain a copy of the License at

  * 

  *      http://www.apache.org/licenses/LICENSE-2.0

  * 

  * Unless required by applicable law or agreed to in writing, software

  * distributed under the License is distributed on an "AS IS" BASIS,

  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

  * See the License for the specific language governing permissions and

  * limitations under the License.

  */

 package org.mockftpserver.core.util;

 import org.mockftpserver.core.CommandSyntaxException;

 import org.mockftpserver.core.MockFtpServerException;

 import java.net.InetAddress;

 import java.net.UnknownHostException;

 import java.util.Arrays;

 import java.util.List;

 /**

  * Utility class for parsing host and port values from command arguments.

  *

  * @author Chris Mair

  * @version $Revision: 232 $ - $Date: 2009-06-13 19:18:01 -0400 (Sat, 13 Jun 2009) $

  */

 public final class PortParser {

     /**

      * Parse the host address and port number of an extended address. This encoded format is used by

      * the EPRT FTP command, and supports IPv6.

      * <p/>

      * The client network address can be in IPv4 format (e.g., "132.235.1.2") or

      * IPv6 format (e.g., "1080::8:800:200C:417A"). See RFC2428 for more information.

      *

      * @param parameter - the single parameter String containing the encoded host and port number

      * @return the populated HostAndPort object

      */

     public static HostAndPort parseExtendedAddressHostAndPort(String parameter) {

         if (parameter == null || parameter.length() == 0) {

             throw new CommandSyntaxException("The parameter string must not be empty or null");

         }

         String delimiter = parameter.substring(0,1);

         String[] tokens = parameter.split("\\" + delimiter);

         if (tokens.length < 4) {

             throw new CommandSyntaxException("Error parsing host and port number [" + parameter + "]");

         }

         int port = Integer.parseInt(tokens[3]);

         InetAddress host;

         try {

             host = InetAddress.getByName(tokens[2]);

         }

         catch (UnknownHostException e) {

             throw new CommandSyntaxException("Error parsing host [" + tokens[2] + "]", e);

         }

         return new HostAndPort(host, port);

     }

     /**

      * Parse a 32-bit IP address and 16-bit port number from the String[] of FTP command parameters.

      * This is used by the FTP "PORT" command.

      *

      * @param parameters - the String[] of command parameters. It is the concatenation

      *                   of a 32-bit internet host address and a 16-bit TCP port address. This address

      *                   information is broken into 8-bit fields and the value of each field is encoded

      *                   as a separate parameter whose value is a decimal number (in character string

      *                   representation).  Thus, the six parameters for the port command would be:

      *                   h1,h2,h3,h4,p1,p2

      *                   where h1 is the high order 8 bits of the internet host address, and p1 is the

      *                   high order 8 bits of the port number.

      * @return the HostAndPort object with the host InetAddres and int port parsed from the parameters

      * @throws org.mockftpserver.core.util.AssertFailedException

      *                               - if parameters is null or contains an insufficient number of elements

      * @throws NumberFormatException - if one of the parameters does not contain a parsable integer

      */

     public static HostAndPort parseHostAndPort(String[] parameters) {

         verifySufficientParameters(parameters);

         byte host1 = parseByte(parameters[0]);

         byte host2 = parseByte(parameters[1]);

         byte host3 = parseByte(parameters[2]);

         byte host4 = parseByte(parameters[3]);

         byte[] address = {host1, host2, host3, host4};

         InetAddress inetAddress = null;

         try {

             inetAddress = InetAddress.getByAddress(address);

         }

         catch (UnknownHostException e) {

             throw new MockFtpServerException("Error parsing host", e);

         }

         int port1 = Integer.parseInt(parameters[4]);

         int port2 = Integer.parseInt(parameters[5]);

         int port = (port1 << 8) + port2;

         return new HostAndPort(inetAddress, port);

     }

     /**

      * Convert the InetAddess and port number to a comma-delimited list of byte values,

      * suitable for the response String from the PASV command.

      *

      * @param host - the InetAddress

      * @param port - the port number

      * @return the comma-delimited list of byte values, e.g., "196,168,44,55,23,77"

      */

     public static String convertHostAndPortToCommaDelimitedBytes(InetAddress host, int port) {

         StringBuffer buffer = new StringBuffer();

         byte[] address = host.getAddress();

         for (int i = 0; i < address.length; i++) {

             int positiveValue = (address[i] >= 0) ? address[i] : 256 + address[i];

             buffer.append(positiveValue);

             buffer.append(",");

         }

         int p1 = port >> 8;

         int p2 = port % 256;

         buffer.append(String.valueOf(p1));

         buffer.append(",");

         buffer.append(String.valueOf(p2));

         return buffer.toString();

     }

     /**

      * Verify that the parameters is not null and contains the required number of elements

      *

      * @param parameters - the String[] of command parameters

      * @throws CommandSyntaxException - if parameters is null or contains an insufficient number of elements

      */

     private static void verifySufficientParameters(String[] parameters) {

         if (parameters == null || parameters.length < 6) {

             List parms = parameters == null ? null : Arrays.asList(parameters);

             throw new CommandSyntaxException("The PORT command must contain least be 6 parameters: " + parms);

         }

     }

     /**

      * Parse the specified String as an unsigned decimal byte value (i.e., 0..255). We can't just use

      * Byte.parseByte(string) because that parses the string as a signed byte.

      *

      * @param string - the String containing the decimal byte representation to be parsed

      * @return the byte value

      */

     private static byte parseByte(String string) {

         return (byte) (0xFF & Short.parseShort(string));

     }

     /**

      * Private constructor. All methods are static.

      */

     private PortParser() {

     }

 }