    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 *      https://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
    020import java.util.Enumeration;
    021import java.util.Vector;
    022
    023/**
    024 * A class used to represent forward and reverse relay paths. The SMTP MAIL command requires a reverse relay path while the SMTP RCPT command requires a forward
    025 * relay path. See RFC 821 for more details. In general, you will not have to deal with relay paths.
    026 *
    027 * @see SMTPClient
    028 */
    029public final class RelayPath {
    030    private final Vector<String> path;
    031    private final String emailAddress;
    032
    033    /**
    034     * Create a relay path with the specified email address as the ultimate destination.
    035     *
    036     * @param emailAddress The destination email address.
    037     */
    038    public RelayPath(final String emailAddress) {
    039        this.path = new Vector<>();
    040        this.emailAddress = emailAddress;
    041    }
    042
    043    /**
    044     * Add a mail relay host to the relay path. Hosts are added left to right. For example, the following will create the path
    045     * {@code <strong> &lt; @bar.com,@foo.com:foobar@foo.com &gt; </strong>}
    046     *
    047     * <pre>
    048     * path = new RelayPath("foobar@foo.com");
    049     * path.addRelay("bar.com");
    050     * path.addRelay("foo.com");
    051     * </pre>
    052     *
    053     * @param hostname The host to add to the relay path.
    054     */
    055    public void addRelay(final String hostname) {
    056        path.addElement(hostname);
    057    }
    058
    059    /**
    060     * Return the properly formatted string representation of the relay path.
    061     *
    062     * @return The properly formatted string representation of the relay path.
    063     */
    064    @Override
    065    public String toString() {
    066        final StringBuilder buffer = new StringBuilder();
    067
    068        buffer.append('<');
    069
    070        final Enumeration<String> hosts = path.elements();
    071
    072        if (hosts.hasMoreElements()) {
    073            buffer.append('@');
    074            buffer.append(hosts.nextElement());
    075
    076            while (hosts.hasMoreElements()) {
    077                buffer.append(",@");
    078                buffer.append(hosts.nextElement());
    079            }
    080            buffer.append(':');
    081        }
    082
    083        buffer.append(emailAddress);
    084        buffer.append('>');
    085
    086        return buffer.toString();
    087    }
    088
    089}