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      1 /*	$NetBSD: punycode.c,v 1.2 2017/01/28 21:31:50 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2004 Kungliga Tekniska Hgskolan
      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