View Javadoc

1   /*
2    * ------------------------------------------------------------------------------
3    * Hermes FTP Server
4    * Copyright (c) 2005-2007 Lars Behnke
5    * ------------------------------------------------------------------------------
6    * 
7    * This file is part of Hermes FTP Server.
8    * 
9    * Hermes FTP Server is free software; you can redistribute it and/or modify
10   * it under the terms of the GNU General Public License as published by
11   * the Free Software Foundation; either version 2 of the License, or
12   * (at your option) any later version.
13   * 
14   * Hermes FTP Server is distributed in the hope that it will be useful,
15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
17   * GNU General Public License for more details.
18   * 
19   * You should have received a copy of the GNU General Public License
20   * along with Hermes FTP Server; if not, write to the Free Software
21   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
22   * ------------------------------------------------------------------------------
23   */
24  
25  package net.sf.hermesftp.cmd.impl;
26  
27  import net.sf.hermesftp.cmd.AbstractFtpCmdPort;
28  
29  /***
30   * <b>DATA PORT (PORT)</b>
31   * <p>
32   * The argument is a HOST-PORT specification for the data port to be used in data connection. There
33   * are defaults for both the user and server data ports, and under normal circumstances this command
34   * and its reply are not needed. If this command is used, the argument is the concatenation of a
35   * 32-bit internet host address and a 16-bit TCP port address. This address information is broken
36   * into 8-bit fields and the value of each field is transmitted as a decimal number (in character
37   * string representation). The fields are separated by commas. A port command would be: PORT
38   * h1,h2,h3,h4,p1,p2 where h1 is the high order 8 bits of the internet host address.
39   * <p>
40   * <i>[Excerpt from RFC-959, Postel and Reynolds]</i>
41   * </p>
42   * 
43   * @author Lars Behnke
44   */
45  public class FtpCmdPort extends AbstractFtpCmdPort {
46  
47      private static final String DOT = ".";
48  
49      private int                 port;
50  
51      private String              addr;
52  
53      private String              lastArgs;
54  
55      /***
56       * {@inheritDoc}
57       */
58      public String getHelp() {
59          return "Sets port for active transfer.";
60      }
61  
62      /***
63       * {@inheritDoc}
64       */
65      protected String doReadIPAddr(String args) {
66          if (!paramsParsed(args)) {
67              parseParams(args);
68          }
69          return addr;
70      }
71  
72      /***
73       * {@inheritDoc}
74       */
75      protected int doReadPort(String args) {
76          if (!paramsParsed(args)) {
77              parseParams(args);
78          }
79          return port;
80      }
81  
82      /***
83       * {@inheritDoc}
84       */
85      protected int doReadProtocolIdx(String args) {
86          return 1;
87      }
88  
89      private boolean paramsParsed(String args) {
90          return lastArgs != null && lastArgs.equals(args);
91      }
92  
93      private void parseParams(String args) {
94          try {
95              lastArgs = args;
96              String[] argParts = getArguments().split(",");
97              int idx = 0;
98              addr = argParts[idx++].trim() + DOT + argParts[idx++].trim() + DOT + argParts[idx++].trim() + DOT
99                      + argParts[idx++].trim();
100             int p1 = Integer.parseInt(argParts[idx++].trim()) & BYTE_MASK;
101             int p2 = Integer.parseInt(argParts[idx++].trim()) & BYTE_MASK;
102             port = (p1 << BYTE_LENGTH) + p2;
103         } catch (Exception e) {
104             throw new IllegalArgumentException("Invalid arguments: " + args);
105         }
106     }
107 
108 }