1 /* $NetBSD: punycode.c,v 1.1.1.1 2011/04/13 18:15:58 elric 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 51 digit(unsigned n) 52 { 53 return "abcdefghijklmnopqrstuvwxyz0123456789"[n]; 54 } 55 56 static unsigned 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 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