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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 | |
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 | |
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 | |
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 | |
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 | |
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 | |
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 */ | |
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