001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.net.smtp;
019
020/**
021 * SMTPCommand stores a set of constants for SMTP command codes. To interpret the meaning of the codes, familiarity with RFC 821 is assumed. The mnemonic
022 * constant names are transcriptions from the code descriptions of RFC 821. For those who think in terms of the actual SMTP commands, a set of constants such as
023 * {@link #HELO HELO } are provided where the constant name is the same as the SMTP command.
024 */
025public final class SMTPCommand {
026
027    /** SMTP command {@value}. */
028    public static final int HELO = 0;
029
030    /** SMTP command {@value}. */
031    public static final int MAIL = 1;
032
033    /** SMTP command {@value}. */
034    public static final int RCPT = 2;
035
036    /** SMTP command {@value}. */
037    public static final int DATA = 3;
038
039    /** SMTP command {@value}. */
040    public static final int SEND = 4;
041
042    /** SMTP command {@value}. */
043    public static final int SOML = 5;
044
045    /** SMTP command {@value}. */
046    public static final int SAML = 6;
047
048    /** SMTP command {@value}. */
049    public static final int RSET = 7;
050
051    /** SMTP command {@value}. */
052    public static final int VRFY = 8;
053
054    /** SMTP command {@value}. */
055    public static final int EXPN = 9;
056
057    /** SMTP command {@value}. */
058    public static final int HELP = 10;
059
060    /** SMTP command {@value}. */
061    public static final int NOOP = 11;
062
063    /** SMTP command {@value}. */
064    public static final int TURN = 12;
065
066    /** SMTP command {@value}. */
067    public static final int QUIT = 13;
068
069    /**
070     * The authorization command
071     *
072     * @since 3.0
073     */
074    public static final int AUTH = 14;
075
076    /**
077     * The extended hello command
078     *
079     * @since 3.0
080     */
081    public static final int EHLO = 15;
082
083    private static final int NEXT = EHLO + 1; // update as necessary when adding new entries
084
085    /** Alias for {@value}. */
086    public static final int HELLO = HELO;
087
088    /** Alias for {@value}. */
089    public static final int LOGIN = HELO;
090
091    /** Alias for {@value}. */
092    public static final int MAIL_FROM = MAIL;
093
094    /** Alias for {@value}. */
095    public static final int RECIPIENT = RCPT;
096
097    /** Alias for {@value}. */
098    public static final int SEND_MESSAGE_DATA = DATA;
099
100    /** Alias for {@value}. */
101    public static final int SEND_FROM = SEND;
102
103    /** Alias for {@value}. */
104    public static final int SEND_OR_MAIL_FROM = SOML;
105
106    /** Alias for {@value}. */
107    public static final int SEND_AND_MAIL_FROM = SAML;
108
109    /** Alias for {@value}. */
110    public static final int RESET = RSET;
111
112    /** Alias for {@value}. */
113    public static final int VERIFY = VRFY;
114
115    /** Alias for {@value}. */
116    public static final int EXPAND = EXPN;
117
118    /** Alias for {@value}. */
119    public static final int LOGOUT = QUIT;
120
121    private static final String[] commands = { "HELO", "MAIL FROM:", "RCPT TO:", "DATA", "SEND FROM:", "SOML FROM:", "SAML FROM:", "RSET", "VRFY", "EXPN",
122            "HELP", "NOOP", "TURN", "QUIT", "AUTH", "EHLO" };
123
124    static {
125        if (commands.length != NEXT) {
126            throw new IllegalStateException("Error in array definition");
127        }
128    }
129
130    /**
131     * Gets the SMTP protocol command string corresponding to a specified command code.
132     *
133     * @param command The command code.
134     * @return The SMTP protocol command string corresponding to a specified command code.
135     */
136    public static String getCommand(final int command) {
137        return commands[command];
138    }
139
140    /** Cannot be instantiated. */
141    private SMTPCommand() {
142    }
143
144}