1 /*
2 *******************************************************************************
3 *
4 * Copyright (C) 2003-2005, International Business Machines
5 * Corporation and others. All Rights Reserved.
6 *
7 *******************************************************************************
8 * file name: punyref.h
9 * encoding: US-ASCII
10 * tab size: 8 (not used)
11 * indentation:4
12 *
13 * created on: 2003feb1
14 * created by: Ram Viswanadha
15 */
16
17 /*
18 Disclaimer and license
19
20 Regarding this entire document or any portion of it (including
21 the pseudocode and C code), the author makes no guarantees and
22 is not responsible for any damage resulting from its use. The
23 author grants irrevocable permission to anyone to use, modify,
24 and distribute it in any way that does not diminish the rights
25 of anyone else to use, modify, and distribute it, provided that
26 redistributed derivative works do not contain misleading author or
27 version information. Derivative works need not be licensed under
28 similar terms.
29
30 punycode.c 0.4.0 (2001-Nov-17-Sat)
31 http://www.cs.berkeley.edu/~amc/idn/
32 Adam M. Costello
33 http://www.nicemice.net/amc/
34 */
35
36 /**********************************************************/
37 /* Implementation (would normally go in its own .c file): */
38
39 #include <string.h>
40
41 #include "unicode/utypes.h"
42
43 #if !UCONFIG_NO_IDNA
44
45 #include "punyref.h"
46
47 /*** Bootstring parameters for Punycode ***/
48
49 enum { base = 36, tmin = 1, tmax = 26, skew = 38, damp = 700,
50 initial_bias = 72, initial_n = 0x80, delimiter = 0x2D };
51
52 /* basic(cp) tests whether cp is a basic code point: */
53 #define basic(cp) ((punycode_uint)(cp) < 0x80)
54
55 /* delim(cp) tests whether cp is a delimiter: */
56 #define delim(cp) ((cp) == delimiter)
57
58 U_CDECL_BEGIN
59 /* decode_digit(cp) returns the numeric value of a basic code */
60 /* point (for use in representing integers) in the range 0 to */
61 /* base-1, or base if cp is does not represent a value. */
62
decode_digit(punycode_uint cp)63 static punycode_uint decode_digit(punycode_uint cp)
64 {
65 return cp - 48 < 10 ? cp - 22 : cp - 65 < 26 ? cp - 65 :
66 cp - 97 < 26 ? cp - 97 : base;
67 }
68
69 /* encode_digit(d,flag) returns the basic code point whose value */
70 /* (when used for representing integers) is d, which needs to be in */
71 /* the range 0 to base-1. The lowercase form is used unless flag is */
72 /* nonzero, in which case the uppercase form is used. The behavior */
73 /* is undefined if flag is nonzero and digit d has no uppercase form. */
74
encode_digit(punycode_uint d,int flag)75 static char encode_digit(punycode_uint d, int flag)
76 {
77 return (char) d + 22 + 75 * (d < 26) - ((flag != 0) << 5);
78 /* 0..25 map to ASCII a..z or A..Z */
79 /* 26..35 map to ASCII 0..9 */
80 }
81
82 /* flagged(bcp) tests whether a basic code point is flagged */
83 /* (uppercase). The behavior is undefined if bcp is not a */
84 /* basic code point. */
85
86 #define flagged(bcp) ((punycode_uint)(bcp) - 65 < 26)
87
88 /* encode_basic(bcp,flag) forces a basic code point to lowercase */
89 /* if flag is zero, uppercase if flag is nonzero, and returns */
90 /* the resulting code point. The code point is unchanged if it */
91 /* is caseless. The behavior is undefined if bcp is not a basic */
92 /* code point. */
93
encode_basic(punycode_uint bcp,int flag)94 static char encode_basic(punycode_uint bcp, int flag)
95 {
96 bcp -= (bcp - 97 < 26) << 5;
97 return (char) bcp + ((!flag && (bcp - 65 < 26)) << 5);
98 }
99
100 /*** Platform-specific constants ***/
101
102 /* maxint is the maximum value of a punycode_uint variable: */
103 static const punycode_uint maxint = (punycode_uint) (-1);
104 /* Because maxint is unsigned, -1 becomes the maximum value. */
105
106 /*** Bias adaptation function ***/
107
adapt(punycode_uint delta,punycode_uint numpoints,int firsttime)108 static punycode_uint adapt(
109 punycode_uint delta, punycode_uint numpoints, int firsttime )
110 {
111 punycode_uint k;
112
113 delta = firsttime ? delta / damp : delta >> 1;
114 /* delta >> 1 is a faster way of doing delta / 2 */
115 delta += delta / numpoints;
116
117 for (k = 0; delta > ((base - tmin) * tmax) / 2; k += base) {
118 delta /= base - tmin;
119 }
120
121 return k + (base - tmin + 1) * delta / (delta + skew);
122 }
123
124 /*** Main encode function ***/
125
punycode_encode(punycode_uint input_length,const punycode_uint input[],const unsigned char case_flags[],punycode_uint * output_length,char output[])126 enum punycode_status punycode_encode(
127 punycode_uint input_length,
128 const punycode_uint input[],
129 const unsigned char case_flags[],
130 punycode_uint *output_length,
131 char output[] )
132 {
133 punycode_uint n, delta, h, b, out, max_out, bias, j, m, q, k, t;
134
135 /* Initialize the state: */
136
137 n = initial_n;
138 delta = out = 0;
139 max_out = *output_length;
140 bias = initial_bias;
141
142 /* Handle the basic code points: */
143
144 for (j = 0; j < input_length; ++j) {
145 if (basic(input[j])) {
146 if (max_out - out < 2) return punycode_big_output;
147 output[out++] = (char)
148 (case_flags ? encode_basic(input[j], case_flags[j]) : input[j]);
149 }
150 /* else if (input[j] < n) return punycode_bad_input; */
151 /* (not needed for Punycode with unsigned code points) */
152 }
153
154 h = b = out;
155
156 /* h is the number of code points that have been handled, b is the */
157 /* number of basic code points, and out is the number of characters */
158 /* that have been output. */
159
160 if (b > 0) output[out++] = delimiter;
161
162 /* Main encoding loop: */
163
164 while (h < input_length) {
165 /* All non-basic code points < n have been */
166 /* handled already. Find the next larger one: */
167
168 for (m = maxint, j = 0; j < input_length; ++j) {
169 /* if (basic(input[j])) continue; */
170 /* (not needed for Punycode) */
171 if (input[j] >= n && input[j] < m) m = input[j];
172 }
173
174 /* Increase delta enough to advance the decoder's */
175 /* <n,i> state to <m,0>, but guard against overflow: */
176
177 if (m - n > (maxint - delta) / (h + 1)) return punycode_overflow;
178 delta += (m - n) * (h + 1);
179 n = m;
180
181 for (j = 0; j < input_length; ++j) {
182 /* Punycode does not need to check whether input[j] is basic: */
183 if (input[j] < n /* || basic(input[j]) */ ) {
184 if (++delta == 0) return punycode_overflow;
185 }
186
187 if (input[j] == n) {
188 /* Represent delta as a generalized variable-length integer: */
189
190 for (q = delta, k = base; ; k += base) {
191 if (out >= max_out) return punycode_big_output;
192 t = k <= bias /* + tmin */ ? tmin : /* +tmin not needed */
193 k >= bias + tmax ? tmax : k - bias;
194 if (q < t) break;
195 output[out++] = encode_digit(t + (q - t) % (base - t), 0);
196 q = (q - t) / (base - t);
197 }
198
199 output[out++] = encode_digit(q, case_flags && case_flags[j]);
200 bias = adapt(delta, h + 1, h == b);
201 delta = 0;
202 ++h;
203 }
204 }
205
206 ++delta, ++n;
207 }
208
209 *output_length = out;
210 return punycode_success;
211 }
212
213 /*** Main decode function ***/
214
punycode_decode(punycode_uint input_length,const char input[],punycode_uint * output_length,punycode_uint output[],unsigned char case_flags[])215 enum punycode_status punycode_decode(
216 punycode_uint input_length,
217 const char input[],
218 punycode_uint *output_length,
219 punycode_uint output[],
220 unsigned char case_flags[] )
221 {
222 punycode_uint n, out, i, max_out, bias,
223 b, j, in, oldi, w, k, digit, t;
224
225 /* Initialize the state: */
226
227 n = initial_n;
228 out = i = 0;
229 max_out = *output_length;
230 bias = initial_bias;
231
232 /* Handle the basic code points: Let b be the number of input code */
233 /* points before the last delimiter, or 0 if there is none, then */
234 /* copy the first b code points to the output. */
235
236 for (b = j = 0; j < input_length; ++j) if (delim(input[j])) b = j;
237 if (b > max_out) return punycode_big_output;
238
239 for (j = 0; j < b; ++j) {
240 if (case_flags) case_flags[out] = flagged(input[j]);
241 if (!basic(input[j])) return punycode_bad_input;
242 output[out++] = input[j];
243 }
244
245 /* Main decoding loop: Start just after the last delimiter if any */
246 /* basic code points were copied; start at the beginning otherwise. */
247
248 for (in = b > 0 ? b + 1 : 0; in < input_length; ++out) {
249
250 /* in is the index of the next character to be consumed, and */
251 /* out is the number of code points in the output array. */
252
253 /* Decode a generalized variable-length integer into delta, */
254 /* which gets added to i. The overflow checking is easier */
255 /* if we increase i as we go, then subtract off its starting */
256 /* value at the end to obtain delta. */
257
258 for (oldi = i, w = 1, k = base; ; k += base) {
259 if (in >= input_length) return punycode_bad_input;
260 digit = decode_digit(input[in++]);
261 if (digit >= base) return punycode_bad_input;
262 if (digit > (maxint - i) / w) return punycode_overflow;
263 i += digit * w;
264 t = k <= bias /* + tmin */ ? tmin : /* +tmin not needed */
265 k >= bias + tmax ? tmax : k - bias;
266 if (digit < t) break;
267 if (w > maxint / (base - t)) return punycode_overflow;
268 w *= (base - t);
269 }
270
271 bias = adapt(i - oldi, out + 1, oldi == 0);
272
273 /* i was supposed to wrap around from out+1 to 0, */
274 /* incrementing n each time, so we'll fix that now: */
275
276 if (i / (out + 1) > maxint - n) return punycode_overflow;
277 n += i / (out + 1);
278 i %= (out + 1);
279
280 /* Insert n at position i of the output: */
281
282 /* not needed for Punycode: */
283 /* if (decode_digit(n) <= base) return punycode_invalid_input; */
284 if (out >= max_out) return punycode_big_output;
285
286 if (case_flags) {
287 memmove(case_flags + i + 1, case_flags + i, out - i);
288 /* Case of last character determines uppercase flag: */
289 case_flags[i] = flagged(input[in - 1]);
290 }
291
292 memmove(output + i + 1, output + i, (out - i) * sizeof *output);
293 output[i++] = n;
294 }
295
296 *output_length = out;
297 return punycode_success;
298 }
299
300 U_CDECL_END
301
302 #endif /* #if !UCONFIG_NO_IDNA */
303