1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  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 */
16
17package java.net;
18
19import libcore.icu.NativeIDN;
20
21/**
22 * Converts internationalized domain names between Unicode and the ASCII Compatible Encoding
23 * (ACE) representation.
24 *
25 * <p>See <a href="http://www.ietf.org/rfc/rfc3490.txt">RFC 3490</a> for full details.
26 *
27 * @since 1.6
28 */
29public final class IDN {
30    /**
31     * When set, allows IDN to process unassigned unicode points.
32     */
33    public static final int ALLOW_UNASSIGNED = 1;
34
35    /**
36     * When set, ASCII strings are checked against
37     * <a href="http://www.ietf.org/rfc/rfc1122.txt">RFC 1122</a> and
38     * <a href="http://www.ietf.org/rfc/rfc1123.txt">RFC 1123</a>.
39     */
40    public static final int USE_STD3_ASCII_RULES = 2;
41
42    private IDN() {
43    }
44
45    /**
46     * Transform a Unicode String to ASCII Compatible Encoding String according
47     * to the algorithm defined in <a href="http://www.ietf.org/rfc/rfc3490.txt">RFC 3490</a>.
48     *
49     * <p>If the transformation fails (because the input is not a valid IDN), an
50     * exception will be thrown.
51     *
52     * <p>This method can handle either an individual label or an entire domain name.
53     * In the latter case, the separators are: U+002E (full stop), U+3002 (ideographic full stop),
54     * U+FF0E (fullwidth full stop), and U+FF61 (halfwidth ideographic full stop).
55     * All of these will become U+002E (full stop) in the result.
56     *
57     * @param input the Unicode name
58     * @param flags 0, {@code ALLOW_UNASSIGNED}, {@code USE_STD3_ASCII_RULES},
59     *         or {@code ALLOW_UNASSIGNED | USE_STD3_ASCII_RULES}
60     * @return the ACE name
61     * @throws IllegalArgumentException if {@code input} does not conform to <a href="http://www.ietf.org/rfc/rfc3490.txt">RFC 3490</a>
62     */
63    public static String toASCII(String input, int flags) {
64        return NativeIDN.toASCII(input, flags);
65    }
66
67    /**
68     * Equivalent to {@code toASCII(input, 0)}.
69     *
70     * @param input the Unicode name
71     * @return the ACE name
72     * @throws IllegalArgumentException if {@code input} does not conform to <a href="http://www.ietf.org/rfc/rfc3490.txt">RFC 3490</a>
73     */
74    public static String toASCII(String input) {
75        return toASCII(input, 0);
76    }
77
78    /**
79     * Translates a string from ASCII Compatible Encoding (ACE) to Unicode
80     * according to the algorithm defined in <a href="http://www.ietf.org/rfc/rfc3490.txt">RFC 3490</a>.
81     *
82     * <p>Unlike {@code toASCII}, this transformation cannot fail.
83     *
84     * <p>This method can handle either an individual label or an entire domain name.
85     * In the latter case, the separators are: U+002E (full stop), U+3002 (ideographic full stop),
86     * U+FF0E (fullwidth full stop), and U+FF61 (halfwidth ideographic full stop).
87     *
88     * @param input the ACE name
89     * @return the Unicode name
90     * @param flags 0, {@code ALLOW_UNASSIGNED}, {@code USE_STD3_ASCII_RULES},
91     *         or {@code ALLOW_UNASSIGNED | USE_STD3_ASCII_RULES}
92     */
93    public static String toUnicode(String input, int flags) {
94        return NativeIDN.toUnicode(input, flags);
95    }
96
97    /**
98     * Equivalent to {@code toUnicode(input, 0)}.
99     *
100     * @param input the ACE name
101     * @return the Unicode name
102     */
103    public static String toUnicode(String input) {
104        return NativeIDN.toUnicode(input, 0);
105    }
106}
107