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/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package ch.boye.httpclientandroidlib.client.utils;
import java.util.StringTokenizer;
import ch.boye.httpclientandroidlib.annotation.Immutable;
/**
* Implementation from pseudo code in RFC 3492.
*
* @since 4.0
*/
@Immutable
public class Rfc3492Idn implements Idn {
private static final int base = 36;
private static final int tmin = 1;
private static final int tmax = 26;
private static final int skew = 38;
private static final int damp = 700;
private static final int initial_bias = 72;
private static final int initial_n = 128;
private static final char delimiter = '-';
private static final String ACE_PREFIX = "xn--";
private int adapt(final int delta, final int numpoints, final boolean firsttime) {
int d = delta;
if (firsttime) {
d = d / damp;
} else {
d = d / 2;
}
d = d + (d / numpoints);
int k = 0;
while (d > ((base - tmin) * tmax) / 2) {
d = d / (base - tmin);
k = k + base;
}
return k + (((base - tmin + 1) * d) / (d + skew));
}
private int digit(final char c) {
if ((c >= 'A') && (c <= 'Z')) {
return (c - 'A');
}
if ((c >= 'a') && (c <= 'z')) {
return (c - 'a');
}
if ((c >= '0') && (c <= '9')) {
return (c - '0') + 26;
}
throw new IllegalArgumentException("illegal digit: "+ c);
}
public String toUnicode(final String punycode) {
final StringBuilder unicode = new StringBuilder(punycode.length());
final StringTokenizer tok = new StringTokenizer(punycode, ".");
while (tok.hasMoreTokens()) {
String t = tok.nextToken();
if (unicode.length() > 0) {
unicode.append('.');
}
if (t.startsWith(ACE_PREFIX)) {
t = decode(t.substring(4));
}
unicode.append(t);
}
return unicode.toString();
}
protected String decode(final String s) {
String input = s;
int n = initial_n;
int i = 0;
int bias = initial_bias;
final StringBuilder output = new StringBuilder(input.length());
final int lastdelim = input.lastIndexOf(delimiter);
if (lastdelim != -1) {
output.append(input.subSequence(0, lastdelim));
input = input.substring(lastdelim + 1);
}
while (input.length() > 0) {
final int oldi = i;
int w = 1;
for (int k = base;; k += base) {
if (input.length() == 0) {
break;
}
final char c = input.charAt(0);
input = input.substring(1);
final int digit = digit(c);
i = i + digit * w; // FIXME fail on overflow
final int t;
if (k <= bias + tmin) {
t = tmin;
} else if (k >= bias + tmax) {
t = tmax;
} else {
t = k - bias;
}
if (digit < t) {
break;
}
w = w * (base - t); // FIXME fail on overflow
}
bias = adapt(i - oldi, output.length() + 1, (oldi == 0));
n = n + i / (output.length() + 1); // FIXME fail on overflow
i = i % (output.length() + 1);
// {if n is a basic code point then fail}
output.insert(i, (char) n);
i++;
}
return output.toString();
}
}
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