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.mail.util;
18
19 import javax.mail.internet.InternetAddress;
20 import java.net.IDN;
21
22 /**
23 * Converts email addresses containing International Domain Names into an ASCII
24 * representation suitable for sending an email.
25 *
26 * @see <a href="https://docs.oracle.com/javase/tutorial/i18n/network/idn.html">https://docs.oracle.com/javase/tutorial/i18n/network/idn.html</a>
27 * @see <a href="https://en.wikipedia.org/wiki/Punycode">https://en.wikipedia.org/wiki/Punycode</a>
28 * @see <a href="https://tools.ietf.org/html/rfc5891">https://tools.ietf.org/html/rfc5891</a>
29 * @see <a href="https://en.wikipedia.org/wiki/Punycode">https://en.wikipedia.org/wiki/Punycode</a>
30 *
31 * @since 1.5
32 */
33 public class IDNEmailAddressConverter
34 {
35 /**
36 * Convert an email address to its ASCII representation using "Punycode".
37 *
38 * @param email email address.
39 * @return The ASCII representation
40 */
41 public String toASCII(final String email)
42 {
43 final int idx = findAtSymbolIndex(email);
44
45 if (idx < 0)
46 {
47 return email;
48 }
49
50 return getLocalPart(email, idx) + '@' + IDN.toASCII(getDomainPart(email, idx));
51 }
52
53 /**
54 * Convert the address part of an InternetAddress to its Unicode representation.
55 *
56 * @param address email address.
57 * @return The Unicode representation
58 */
59 String toUnicode(final InternetAddress address)
60 {
61 return address != null ? toUnicode(address.getAddress()) : null;
62 }
63
64 /**
65 * Convert an "Punycode" email address to its Unicode representation.
66 *
67 * @param email email address.
68 * @return The Unicode representation
69 */
70 String toUnicode(final String email)
71 {
72 final int idx = findAtSymbolIndex(email);
73
74 if (idx < 0)
75 {
76 return email;
77 }
78
79 return getLocalPart(email, idx) + '@' + IDN.toUnicode(getDomainPart(email, idx));
80 }
81
82 /**
83 * Extracts the local part of the email address.
84 *
85 * @param email email address.
86 * @param idx index of '@' character.
87 * @return local part of email
88 */
89 private String getLocalPart(final String email, final int idx)
90 {
91 return email.substring(0, idx);
92 }
93
94 /**
95 * Extracts the domain part of the email address.
96 *
97 * @param email email address.
98 * @param idx index of '@' character.
99 * @return domain part of email
100 */
101 private String getDomainPart(final String email, final int idx)
102 {
103 return email.substring(idx + 1);
104 }
105
106 /**
107 * Null-safe wrapper for {@link String#indexOf} to find the '@' character.
108 *
109 * @param value String value.
110 * @return index of first '@' character or {@code -1}
111 */
112 private int findAtSymbolIndex(final String value)
113 {
114 if (value == null)
115 {
116 return -1;
117 }
118
119 return value.indexOf('@');
120 }
121 }