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Import Punycode reference implementation.

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Chris Young 2014-05-30 20:02:29 +01:00 committed by Daniel Silverstone
parent 9fb4fd738a
commit 9d2d717e9f
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/*
punycode-sample.c 2.0.0 (2004-Mar-21-Sun)
http://www.nicemice.net/idn/
Adam M. Costello
http://www.nicemice.net/amc/
This is ANSI C code (C89) implementing Punycode 1.0.x.
*/
/**********************************************************/
/* Implementation (would normally go in its own .c file): */
#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 ***/
enum punycode_status punycode_encode(
size_t input_length_orig,
const punycode_uint input[],
const unsigned char case_flags[],
size_t *output_length,
char output[] )
{
punycode_uint input_length, 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_orig > maxint) return punycode_overflow;
input_length = (punycode_uint) input_length_orig;
/* 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_length; ++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_length <= 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_length) {
/* All non-basic code points < n have been */
/* handled already. Find the next larger one: */
for (m = maxint, j = 0; j < input_length; ++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_length; ++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 ***/
enum punycode_status 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_bad_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;
}

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/*
punycode-sample.c 2.0.0 (2004-Mar-21-Sun)
http://www.nicemice.net/idn/
Adam M. Costello
http://www.nicemice.net/amc/
This is ANSI C code (C89) implementing Punycode 1.0.x.
This single file contains three sections (an interface, an
implementation, and a wrapper for testing) that would normally belong
in three separate files (punycode.h, punycode.c, punycode-test.c), but
here they are bundled into one file (punycode-sample.c) for convenient
testing. Anyone wishing to reuse this code will probably want to split
it apart.
*/
/************************************************************/
/* Public interface (would normally go in its own .h file): */
#include <limits.h>
#include <stddef.h>
enum punycode_status {
punycode_success = 0,
punycode_bad_input = 1, /* Input is invalid. */
punycode_big_output = 2, /* Output would exceed the space provided. */
punycode_overflow = 3 /* Wider integers needed to process input. */
};
/* punycode_uint needs to be unsigned and needs to be */
/* at least 26 bits wide. The particular type can be */
/* specified by defining PUNYCODE_UINT, otherwise a */
/* suitable type will be chosen automatically. */
#ifdef PUNYCODE_UINT
typedef PUNYCODE_UINT punycode_uint;
#elif UINT_MAX >= (1 << 26) - 1
typedef unsigned int punycode_uint;
#else
typedef unsigned long punycode_uint;
#endif
enum punycode_status punycode_encode(
size_t, /* input_length */
const punycode_uint [], /* input */
const unsigned char [], /* case_flags */
size_t *, /* output_length */
char [] /* output */
);
/*
punycode_encode() converts a sequence of code points (presumed to be
Unicode code points) to Punycode.
Input arguments (to be supplied by the caller):
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 necessary. 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 arguments (to be filled in by the function):
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.)
Input/output arguments (to be supplied by the caller and overwritten
by the function):
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.
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.
*/
enum punycode_status punycode_decode(
size_t, /* input_length */
const char [], /* input */
size_t *, /* output_length */
punycode_uint [], /* output */
unsigned char [] /* case_flags */
);
/*
punycode_decode() converts Punycode to a sequence of code points
(presumed to be Unicode code points).
Input arguments (to be supplied by the caller):
input_length
The number of ASCII code points in the input array.
input
An array of ASCII code points (0..7F).
Output arguments (to be filled in by the function):
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.
Input/output arguments (to be supplied by the caller and overwritten
by the function):
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.
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.
*/