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Diffstat (limited to 'libidn/punycode.c')
| -rw-r--r-- | libidn/punycode.c | 456 |
1 files changed, 456 insertions, 0 deletions
diff --git a/libidn/punycode.c b/libidn/punycode.c new file mode 100644 index 0000000000..372f849c02 --- /dev/null +++ b/libidn/punycode.c @@ -0,0 +1,456 @@ +/* punycode.c Implementation of punycode used to ASCII encode IDN's. + * Copyright (C) 2002, 2003 Simon Josefsson + * + * This file is part of GNU Libidn. + * + * GNU Libidn is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * GNU Libidn is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with GNU Libidn; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + */ + +/* + * This file is derived from RFC 3492bis written by Adam M. Costello. + * + * Disclaimer and license: Regarding this entire document or any + * portion of it (including the pseudocode and C code), the author + * makes no guarantees and is not responsible for any damage resulting + * from its use. The author grants irrevocable permission to anyone + * to use, modify, and distribute it in any way that does not diminish + * the rights of anyone else to use, modify, and distribute it, + * provided that redistributed derivative works do not contain + * misleading author or version information. Derivative works need + * not be licensed under similar terms. + * + * Copyright (C) The Internet Society (2003). All Rights Reserved. + * + * This document and translations of it may be copied and furnished to + * others, and derivative works that comment on or otherwise explain it + * or assist in its implementation may be prepared, copied, published + * and distributed, in whole or in part, without restriction of any + * kind, provided that the above copyright notice and this paragraph are + * included on all such copies and derivative works. However, this + * document itself may not be modified in any way, such as by removing + * the copyright notice or references to the Internet Society or other + * Internet organizations, except as needed for the purpose of + * developing Internet standards in which case the procedures for + * copyrights defined in the Internet Standards process must be + * followed, or as required to translate it into languages other than + * English. + * + * The limited permissions granted above are perpetual and will not be + * revoked by the Internet Society or its successors or assigns. + * + * This document and the information contained herein is provided on an + * "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING + * TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING + * BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION + * HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. + */ + +#include <string.h> + +#include "punycode.h" + +/*** Bootstring parameters for Punycode ***/ + +enum +{ base = 36, tmin = 1, tmax = 26, skew = 38, damp = 700, + initial_bias = 72, initial_n = 0x80, delimiter = 0x2D +}; + +/* basic(cp) tests whether cp is a basic code point: */ +#define basic(cp) ((punycode_uint)(cp) < 0x80) + +/* delim(cp) tests whether cp is a delimiter: */ +#define delim(cp) ((cp) == delimiter) + +/* decode_digit(cp) returns the numeric value of a basic code */ +/* point (for use in representing integers) in the range 0 to */ +/* base-1, or base if cp does not represent a value. */ + +static punycode_uint +decode_digit (punycode_uint cp) +{ + return cp - 48 < 10 ? cp - 22 : cp - 65 < 26 ? cp - 65 : + cp - 97 < 26 ? cp - 97 : base; +} + +/* encode_digit(d,flag) returns the basic code point whose value */ +/* (when used for representing integers) is d, which needs to be in */ +/* the range 0 to base-1. The lowercase form is used unless flag is */ +/* nonzero, in which case the uppercase form is used. The behavior */ +/* is undefined if flag is nonzero and digit d has no uppercase form. */ + +static char +encode_digit (punycode_uint d, int flag) +{ + return d + 22 + 75 * (d < 26) - ((flag != 0) << 5); + /* 0..25 map to ASCII a..z or A..Z */ + /* 26..35 map to ASCII 0..9 */ +} + +/* flagged(bcp) tests whether a basic code point is flagged */ +/* (uppercase). The behavior is undefined if bcp is not a */ +/* basic code point. */ + +#define flagged(bcp) ((punycode_uint)(bcp) - 65 < 26) + +/* encode_basic(bcp,flag) forces a basic code point to lowercase */ +/* if flag is zero, uppercase if flag is nonzero, and returns */ +/* the resulting code point. The code point is unchanged if it */ +/* is caseless. The behavior is undefined if bcp is not a basic */ +/* code point. */ + +static char +encode_basic (punycode_uint bcp, int flag) +{ + bcp -= (bcp - 97 < 26) << 5; + return bcp + ((!flag && (bcp - 65 < 26)) << 5); +} + +/*** Platform-specific constants ***/ + +/* maxint is the maximum value of a punycode_uint variable: */ +static const punycode_uint maxint = -1; +/* Because maxint is unsigned, -1 becomes the maximum value. */ + +/*** Bias adaptation function ***/ + +static punycode_uint +adapt (punycode_uint delta, punycode_uint numpoints, int firsttime) +{ + punycode_uint k; + + delta = firsttime ? delta / damp : delta >> 1; + /* delta >> 1 is a faster way of doing delta / 2 */ + delta += delta / numpoints; + + for (k = 0; delta > ((base - tmin) * tmax) / 2; k += base) + { + delta /= base - tmin; + } + + return k + (base - tmin + 1) * delta / (delta + skew); +} + +/*** Main encode function ***/ + +/** + * punycode_encode: + * @input_length: The number of code points in the @input array and + * the number of flags in the @case_flags array. + * @input: An array of code points. They are presumed to be Unicode + * code points, but that is not strictly REQUIRED. The array + * contains code points, not code units. UTF-16 uses code units + * D800 through DFFF to refer to code points 10000..10FFFF. The + * code points D800..DFFF do not occur in any valid Unicode string. + * The code points that can occur in Unicode strings (0..D7FF and + * E000..10FFFF) are also called Unicode scalar values. + * @case_flags: A %NULL pointer or an array of boolean values parallel + * to the @input array. Nonzero (true, flagged) suggests that the + * corresponding Unicode character be forced to uppercase after + * being decoded (if possible), and zero (false, unflagged) suggests + * that it be forced to lowercase (if possible). ASCII code points + * (0..7F) are encoded literally, except that ASCII letters are + * forced to uppercase or lowercase according to the corresponding + * case flags. If @case_flags is a %NULL pointer then ASCII letters + * are left as they are, and other code points are treated as + * unflagged. + * @output_length: The caller passes in the maximum number of ASCII + * code points that it can receive. On successful return it will + * contain the number of ASCII code points actually output. + * @output: An array of ASCII code points. It is *not* + * null-terminated; it will contain zeros if and only if the @input + * contains zeros. (Of course the caller can leave room for a + * terminator and add one if needed.) + * + * Converts a sequence of code points (presumed to be Unicode code + * points) to Punycode. + * + * Return value: The return value can be any of the punycode_status + * values defined above except %punycode_bad_input. If not + * %punycode_success, then @output_size and @output might contain + * garbage. + **/ +int +punycode_encode (size_t input_length, + const punycode_uint input[], + const unsigned char case_flags[], + size_t * output_length, char output[]) +{ + punycode_uint input_len, n, delta, h, b, bias, j, m, q, k, t; + size_t out, max_out; + + /* The Punycode spec assumes that the input length is the same type */ + /* of integer as a code point, so we need to convert the size_t to */ + /* a punycode_uint, which could overflow. */ + + if (input_length > maxint) + return punycode_overflow; + input_len = (punycode_uint) input_length; + + /* Initialize the state: */ + + n = initial_n; + delta = 0; + out = 0; + max_out = *output_length; + bias = initial_bias; + + /* Handle the basic code points: */ + + for (j = 0; j < input_len; ++j) + { + if (basic (input[j])) + { + if (max_out - out < 2) + return punycode_big_output; + output[out++] = case_flags ? + encode_basic (input[j], case_flags[j]) : (char) input[j]; + } + /* else if (input[j] < n) return punycode_bad_input; */ + /* (not needed for Punycode with unsigned code points) */ + } + + h = b = (punycode_uint) out; + /* cannot overflow because out <= input_len <= maxint */ + + /* h is the number of code points that have been handled, b is the */ + /* number of basic code points, and out is the number of ASCII code */ + /* points that have been output. */ + + if (b > 0) + output[out++] = delimiter; + + /* Main encoding loop: */ + + while (h < input_len) + { + /* All non-basic code points < n have been */ + /* handled already. Find the next larger one: */ + + for (m = maxint, j = 0; j < input_len; ++j) + { + /* if (basic(input[j])) continue; */ + /* (not needed for Punycode) */ + if (input[j] >= n && input[j] < m) + m = input[j]; + } + + /* Increase delta enough to advance the decoder's */ + /* <n,i> state to <m,0>, but guard against overflow: */ + + if (m - n > (maxint - delta) / (h + 1)) + return punycode_overflow; + delta += (m - n) * (h + 1); + n = m; + + for (j = 0; j < input_len; ++j) + { + /* Punycode does not need to check whether input[j] is basic: */ + if (input[j] < n /* || basic(input[j]) */ ) + { + if (++delta == 0) + return punycode_overflow; + } + + if (input[j] == n) + { + /* Represent delta as a generalized variable-length integer: */ + + for (q = delta, k = base;; k += base) + { + if (out >= max_out) + return punycode_big_output; + t = k <= bias /* + tmin */ ? tmin : /* +tmin not needed */ + k >= bias + tmax ? tmax : k - bias; + if (q < t) + break; + output[out++] = encode_digit (t + (q - t) % (base - t), 0); + q = (q - t) / (base - t); + } + + output[out++] = encode_digit (q, case_flags && case_flags[j]); + bias = adapt (delta, h + 1, h == b); + delta = 0; + ++h; + } + } + + ++delta, ++n; + } + + *output_length = out; + return punycode_success; +} + +/*** Main decode function ***/ + +/** + * punycode_decode: + * @input_length: The number of ASCII code points in the @input array. + * @input: An array of ASCII code points (0..7F). + * @output_length: The caller passes in the maximum number of code + * points that it can receive into the @output array (which is also + * the maximum number of flags that it can receive into the + * @case_flags array, if @case_flags is not a %NULL pointer). On + * successful return it will contain the number of code points + * actually output (which is also the number of flags actually + * output, if case_flags is not a null pointer). The decoder will + * never need to output more code points than the number of ASCII + * code points in the input, because of the way the encoding is + * defined. The number of code points output cannot exceed the + * maximum possible value of a punycode_uint, even if the supplied + * @output_length is greater than that. + * @output: An array of code points like the input argument of + * punycode_encode() (see above). + * @case_flags: A %NULL pointer (if the flags are not needed by the + * caller) or an array of boolean values parallel to the @output + * array. Nonzero (true, flagged) suggests that the corresponding + * Unicode character be forced to uppercase by the caller (if + * possible), and zero (false, unflagged) suggests that it be forced + * to lowercase (if possible). ASCII code points (0..7F) are output + * already in the proper case, but their flags will be set + * appropriately so that applying the flags would be harmless. + * + * Converts Punycode to a sequence of code points (presumed to be + * Unicode code points). + * + * Return value: The return value can be any of the punycode_status + * values defined above. If not %punycode_success, then + * @output_length, @output, and @case_flags might contain garbage. + * + **/ +int +punycode_decode (size_t input_length, + const char input[], + size_t * output_length, + punycode_uint output[], unsigned char case_flags[]) +{ + punycode_uint n, out, i, max_out, bias, oldi, w, k, digit, t; + size_t b, j, in; + + /* Initialize the state: */ + + n = initial_n; + out = i = 0; + max_out = *output_length > maxint ? maxint + : (punycode_uint) * output_length; + bias = initial_bias; + + /* Handle the basic code points: Let b be the number of input code */ + /* points before the last delimiter, or 0 if there is none, then */ + /* copy the first b code points to the output. */ + + for (b = j = 0; j < input_length; ++j) + if (delim (input[j])) + b = j; + if (b > max_out) + return punycode_big_output; + + for (j = 0; j < b; ++j) + { + if (case_flags) + case_flags[out] = flagged (input[j]); + if (!basic (input[j])) + return punycode_bad_input; + output[out++] = input[j]; + } + + /* Main decoding loop: Start just after the last delimiter if any */ + /* basic code points were copied; start at the beginning otherwise. */ + + for (in = b > 0 ? b + 1 : 0; in < input_length; ++out) + { + + /* in is the index of the next ASCII code point to be consumed, */ + /* and out is the number of code points in the output array. */ + + /* Decode a generalized variable-length integer into delta, */ + /* which gets added to i. The overflow checking is easier */ + /* if we increase i as we go, then subtract off its starting */ + /* value at the end to obtain delta. */ + + for (oldi = i, w = 1, k = base;; k += base) + { + if (in >= input_length) + return punycode_bad_input; + digit = decode_digit (input[in++]); + if (digit >= base) + return punycode_bad_input; + if (digit > (maxint - i) / w) + return punycode_overflow; + i += digit * w; + t = k <= bias /* + tmin */ ? tmin : /* +tmin not needed */ + k >= bias + tmax ? tmax : k - bias; + if (digit < t) + break; + if (w > maxint / (base - t)) + return punycode_overflow; + w *= (base - t); + } + + bias = adapt (i - oldi, out + 1, oldi == 0); + + /* i was supposed to wrap around from out+1 to 0, */ + /* incrementing n each time, so we'll fix that now: */ + + if (i / (out + 1) > maxint - n) + return punycode_overflow; + n += i / (out + 1); + i %= (out + 1); + + /* Insert n at position i of the output: */ + + /* not needed for Punycode: */ + /* if (basic(n)) return punycode_invalid_input; */ + if (out >= max_out) + return punycode_big_output; + + if (case_flags) + { + memmove (case_flags + i + 1, case_flags + i, out - i); + /* Case of last ASCII code point determines case flag: */ + case_flags[i] = flagged (input[in - 1]); + } + + memmove (output + i + 1, output + i, (out - i) * sizeof *output); + output[i++] = n; + } + + *output_length = (size_t) out; + /* cannot overflow because out <= old value of *output_length */ + return punycode_success; +} + +/** + * punycode_uint + * + * Unicode code point data type, this is always a 32 bit unsigned + * integer. + */ + +/** + * Punycode_status + * @PUNYCODE_SUCCESS: Successful operation. This value is guaranteed + * to always be zero, the remaining ones are only guaranteed to hold + * non-zero values, for logical comparison purposes. + * @PUNYCODE_BAD_INPUT: Input is invalid. + * @PUNYCODE_BIG_OUTPUT: Output would exceed the space provided. + * @PUNYCODE_OVERFLOW: Input needs wider integers to process. + * + * Enumerated return codes of punycode_encode() and punycode_decode(). + * The value 0 is guaranteed to always correspond to success. + */ |