1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.mail2.jakarta.util;
18
19 import java.net.IDN;
20 import java.util.function.Function;
21
22 import jakarta.mail.internet.InternetAddress;
23
24 /**
25 * Converts email addresses containing International Domain Names into an ASCII representation suitable for sending an email.
26 *
27 * @see <a href="https://docs.oracle.com/javase/tutorial/i18n/network/idn.html">https://docs.oracle.com/javase/tutorial/i18n/network/idn.html</a>
28 * @see <a href="https://en.wikipedia.org/wiki/Punycode">https://en.wikipedia.org/wiki/Punycode</a>
29 * @see <a href="https://tools.ietf.org/html/rfc5891">https://tools.ietf.org/html/rfc5891</a>
30 * @see <a href="https://en.wikipedia.org/wiki/Punycode">https://en.wikipedia.org/wiki/Punycode</a>
31 *
32 * @since 1.5
33 */
34 public class IDNEmailAddressConverter {
35
36 /**
37 * Constructs a new instance.
38 */
39 public IDNEmailAddressConverter() {
40 // empty
41 }
42
43 /**
44 * Extracts the domain part of the email address.
45 *
46 * @param email email address.
47 * @param idx index of '@' character.
48 * @return domain part of email
49 */
50 private String getDomainPart(final String email, final int idx) {
51 return email.substring(idx + 1);
52 }
53
54 /**
55 * Extracts the local part of the email address.
56 *
57 * @param email email address.
58 * @param idx index of '@' character.
59 * @return local part of email
60 */
61 private String getLocalPart(final String email, final int idx) {
62 return email.substring(0, idx);
63 }
64
65 /**
66 * Converts an email address to its ASCII representation using "Punycode".
67 *
68 * @param email email address.
69 * @return The ASCII representation
70 */
71 public String toASCII(final String email) {
72 return toString(email, IDN::toASCII);
73 }
74
75 private String toString(final String email, final Function<String, String> converter) {
76 final int idx = email == null ? -1 : email.indexOf('@');
77 if (idx < 0) {
78 return email;
79 }
80 return getLocalPart(email, idx) + '@' + converter.apply(getDomainPart(email, idx));
81 }
82
83 /**
84 * Converts the address part of an InternetAddress to its Unicode representation.
85 *
86 * @param address email address.
87 * @return The Unicode representation
88 */
89 String toUnicode(final InternetAddress address) {
90 return address != null ? toUnicode(address.getAddress()) : null;
91 }
92
93 /**
94 * Converts an "Punycode" email address to its Unicode representation.
95 *
96 * @param email email address.
97 * @return The Unicode representation
98 */
99 String toUnicode(final String email) {
100 return toString(email, IDN::toUnicode);
101 }
102 }