PortParser.java revision d8cb70b52ca9f78d526ccd9cf67e4f4345ecdc95 
1/*
2 * Copyright 2008 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16package org.mockftpserver.core.util;
17
18import java.net.InetAddress;
19import java.net.UnknownHostException;
20import java.util.Arrays;
21
22/**
23 * Utility class for parsing port values from command arguments.
24 *
25 * @author Chris Mair
26 * @version $Revision$ - $Date$
27 */
28public final class PortParser {
29
30    /**
31     * Private constructor. All methods are static.
32     */
33    private PortParser() {
34    }
35
36    /**
37     * Parse a 32-bit IP address from the String[] of FTP command parameters.
38     *
39     * @param parameters - the String[] of command parameters. It is the concatenation
40     *                   of a 32-bit internet host address and a 16-bit TCP port address. This address
41     *                   information is broken into 8-bit fields and the value of each field is encoded
42     *                   as a separate parameter whose value is a decimal number (in character string
43     *                   representation).  Thus, the six parameters for the port command would be:
44     *                   h1,h2,h3,h4,p1,p2
45     *                   where h1 is the high order 8 bits of the internet host address, and p1 is the
46     *                   high order 8 bits of the port number.
47     * @return the InetAddres representing the host parsed from the parameters
48     * @throws org.mockftpserver.core.util.AssertFailedException
49     *                                       - if parameters is null or contains an insufficient number of elements
50     * @throws NumberFormatException         - if one of the parameters does not contain a parsable integer
51     * @throws java.net.UnknownHostException
52     */
53    public static InetAddress parseHost(String[] parameters) throws UnknownHostException {
54        verifySufficientParameters(parameters);
55
56        byte host1 = Byte.parseByte(parameters[0]);
57        byte host2 = Byte.parseByte(parameters[1]);
58        byte host3 = Byte.parseByte(parameters[2]);
59        byte host4 = Byte.parseByte(parameters[3]);
60
61        byte[] address = {host1, host2, host3, host4};
62        InetAddress inetAddress = InetAddress.getByAddress(address);
63
64        return inetAddress;
65    }
66
67    /**
68     * Parse a 16-bit port number from the String[] of FTP command parameters.
69     *
70     * @param parameters - the String[] of command parameters. It is the concatenation
71     *                   of a 32-bit internet host address and a 16-bit TCP port address. This address
72     *                   information is broken into 8-bit fields and the value of each field is encoded
73     *                   as a separate parameter whose value is a decimal number (in character string
74     *                   representation).  Thus, the six parameters for the port command would be:
75     *                   h1,h2,h3,h4,p1,p2
76     *                   where h1 is the high order 8 bits of the internet host address, and p1 is the
77     *                   high order 8 bits of the port number.
78     * @return the port number parsed from the parameters
79     * @throws org.mockftpserver.core.util.AssertFailedException
80     *                               - if parameters is null or contains an insufficient number of elements
81     * @throws NumberFormatException - if one of the parameters does not contain a parsable integer
82     */
83    public static int parsePortNumber(String[] parameters) {
84        verifySufficientParameters(parameters);
85
86        int port1 = Integer.parseInt(parameters[4]);
87        int port2 = Integer.parseInt(parameters[5]);
88        int port = (port1 << 8) + port2;
89
90        return port;
91    }
92
93    /**
94     * Verify that the parameters is not null and contains the required number of elements
95     *
96     * @param parameters - the String[] of command parameters
97     * @throws org.mockftpserver.core.util.AssertFailedException
98     *          - if parameters is null or contains an insufficient number of elements
99     */
100    private static void verifySufficientParameters(String[] parameters) {
101        Assert.notNull(parameters, "parameters");
102        Assert.isTrue(parameters.length >= 6, "The PORT command must contain least be 6 parameters: " + Arrays.asList(parameters));
103    }
104
105}