1 /* $NetBSD: punycode.c,v 1.2 2017/01/28 21:31:50 christos Exp $ */
2
3 /*
4 * Copyright (c) 2004 Kungliga Tekniska Högskolan
5 * (Royal Institute of Technology, Stockholm, Sweden).
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * 3. Neither the name of the Institute nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #ifdef HAVE_CONFIG_H
37 #include <config.h>
38 #endif
39 #include <string.h>
40 #include "windlocl.h"
41
42 static const unsigned base = 36;
43 static const unsigned t_min = 1;
44 static const unsigned t_max = 26;
45 static const unsigned skew = 38;
46 static const unsigned damp = 700;
47 static const unsigned initial_n = 128;
48 static const unsigned initial_bias = 72;
49
50 static unsigned
digit(unsigned n)51 digit(unsigned n)
52 {
53 return "abcdefghijklmnopqrstuvwxyz0123456789"[n];
54 }
55
56 static unsigned
adapt(unsigned delta,unsigned numpoints,int first)57 adapt(unsigned delta, unsigned numpoints, int first)
58 {
59 unsigned k;
60
61 if (first)
62 delta = delta / damp;
63 else
64 delta /= 2;
65 delta += delta / numpoints;
66 k = 0;
67 while (delta > ((base - t_min) * t_max) / 2) {
68 delta /= base - t_min;
69 k += base;
70 }
71 return k + (((base - t_min + 1) * delta) / (delta + skew));
72 }
73
74 /**
75 * Convert an UCS4 string to a puny-coded DNS label string suitable
76 * when combined with delimiters and other labels for DNS lookup.
77 *
78 * @param in an UCS4 string to convert
79 * @param in_len the length of in.
80 * @param out the resulting puny-coded string. The string is not NUL
81 * terminatied.
82 * @param out_len before processing out_len should be the length of
83 * the out variable, after processing it will be the length of the out
84 * string.
85 *
86 * @return returns 0 on success, an wind error code otherwise
87 * @ingroup wind
88 */
89
90 int
wind_punycode_label_toascii(const uint32_t * in,size_t in_len,char * out,size_t * out_len)91 wind_punycode_label_toascii(const uint32_t *in, size_t in_len,
92 char *out, size_t *out_len)
93 {
94 unsigned n = initial_n;
95 unsigned delta = 0;
96 unsigned bias = initial_bias;
97 unsigned h = 0;
98 unsigned b;
99 unsigned i;
100 unsigned o = 0;
101 unsigned m;
102
103 for (i = 0; i < in_len; ++i) {
104 if (in[i] < 0x80) {
105 ++h;
106 if (o >= *out_len)
107 return WIND_ERR_OVERRUN;
108 out[o++] = in[i];
109 }
110 }
111 b = h;
112 if (b > 0) {
113 if (o >= *out_len)
114 return WIND_ERR_OVERRUN;
115 out[o++] = 0x2D;
116 }
117 /* is this string punycoded */
118 if (h < in_len) {
119 if (o + 4 >= *out_len)
120 return WIND_ERR_OVERRUN;
121 memmove(out + 4, out, o);
122 memcpy(out, "xn--", 4);
123 o += 4;
124 }
125
126 while (h < in_len) {
127 m = (unsigned)-1;
128 for (i = 0; i < in_len; ++i)
129 if(in[i] < m && in[i] >= n)
130 m = in[i];
131
132 delta += (m - n) * (h + 1);
133 n = m;
134 for (i = 0; i < in_len; ++i) {
135 if (in[i] < n) {
136 ++delta;
137 } else if (in[i] == n) {
138 unsigned q = delta;
139 unsigned k;
140 for (k = base; ; k += base) {
141 unsigned t;
142 if (k <= bias)
143 t = t_min;
144 else if (k >= bias + t_max)
145 t = t_max;
146 else
147 t = k - bias;
148 if (q < t)
149 break;
150 if (o >= *out_len)
151 return WIND_ERR_OVERRUN;
152 out[o++] = digit(t + ((q - t) % (base - t)));
153 q = (q - t) / (base - t);
154 }
155 if (o >= *out_len)
156 return WIND_ERR_OVERRUN;
157 out[o++] = digit(q);
158 /* output */
159 bias = adapt(delta, h + 1, h == b);
160 delta = 0;
161 ++h;
162 }
163 }
164 ++delta;
165 ++n;
166 }
167
168 *out_len = o;
169 return 0;
170 }
171