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<?php
/**
* IDNA URL encoder
*
* Note: Not fully compliant, as nameprep does nothing yet.
*
* @package Requests
* @subpackage Utilities
* @see https://tools.ietf.org/html/rfc3490 IDNA specification
* @see https://tools.ietf.org/html/rfc3492 Punycode/Bootstrap specification
*/
class Requests_IDNAEncoder {
/**
* ACE prefix used for IDNA
*
* @see https://tools.ietf.org/html/rfc3490#section-5
* @var string
*/
const ACE_PREFIX = 'xn--';
/**#@+
* Bootstrap constant for Punycode
*
* @see https://tools.ietf.org/html/rfc3492#section-5
* @var int
*/
const BOOTSTRAP_BASE = 36;
const BOOTSTRAP_TMIN = 1;
const BOOTSTRAP_TMAX = 26;
const BOOTSTRAP_SKEW = 38;
const BOOTSTRAP_DAMP = 700;
const BOOTSTRAP_INITIAL_BIAS = 72;
const BOOTSTRAP_INITIAL_N = 128;
/**#@-*/
/**
* Encode a hostname using Punycode
*
* @param string $string Hostname
* @return string Punycode-encoded hostname
*/
public static function encode($string) {
$parts = explode('.', $string);
foreach ($parts as &$part) {
$part = self::to_ascii($part);
}
return implode('.', $parts);
}
/**
* Convert a UTF-8 string to an ASCII string using Punycode
*
* @throws Requests_Exception Provided string longer than 64 ASCII characters (`idna.provided_too_long`)
* @throws Requests_Exception Prepared string longer than 64 ASCII characters (`idna.prepared_too_long`)
* @throws Requests_Exception Provided string already begins with xn-- (`idna.provided_is_prefixed`)
* @throws Requests_Exception Encoded string longer than 64 ASCII characters (`idna.encoded_too_long`)
*
* @param string $string ASCII or UTF-8 string (max length 64 characters)
* @return string ASCII string
*/
public static function to_ascii($string) {
// Step 1: Check if the string is already ASCII
if (self::is_ascii($string)) {
// Skip to step 7
if (strlen($string) < 64) {
return $string;
}
throw new Requests_Exception('Provided string is too long', 'idna.provided_too_long', $string);
}
// Step 2: nameprep
$string = self::nameprep($string);
// Step 3: UseSTD3ASCIIRules is false, continue
// Step 4: Check if it's ASCII now
if (self::is_ascii($string)) {
// Skip to step 7
if (strlen($string) < 64) {
return $string;
}
throw new Requests_Exception('Prepared string is too long', 'idna.prepared_too_long', $string);
}
// Step 5: Check ACE prefix
if (strpos($string, self::ACE_PREFIX) === 0) {
throw new Requests_Exception('Provided string begins with ACE prefix', 'idna.provided_is_prefixed', $string);
}
// Step 6: Encode with Punycode
$string = self::punycode_encode($string);
// Step 7: Prepend ACE prefix
$string = self::ACE_PREFIX . $string;
// Step 8: Check size
if (strlen($string) < 64) {
return $string;
}
throw new Requests_Exception('Encoded string is too long', 'idna.encoded_too_long', $string);
}
/**
* Check whether a given string contains only ASCII characters
*
* @internal (Testing found regex was the fastest implementation)
*
* @param string $string
* @return bool Is the string ASCII-only?
*/
protected static function is_ascii($string) {
return (preg_match('/(?:[^\x00-\x7F])/', $string) !== 1);
}
/**
* Prepare a string for use as an IDNA name
*
* @todo Implement this based on RFC 3491 and the newer 5891
* @param string $string
* @return string Prepared string
*/
protected static function nameprep($string) {
return $string;
}
/**
* Convert a UTF-8 string to a UCS-4 codepoint array
*
* Based on Requests_IRI::replace_invalid_with_pct_encoding()
*
* @throws Requests_Exception Invalid UTF-8 codepoint (`idna.invalidcodepoint`)
* @param string $input
* @return array Unicode code points
*/
protected static function utf8_to_codepoints($input) {
$codepoints = array();
// Get number of bytes
$strlen = strlen($input);
for ($position = 0; $position < $strlen; $position++) {
$value = ord($input[$position]);
// One byte sequence:
if ((~$value & 0x80) === 0x80) {
$character = $value;
$length = 1;
$remaining = 0;
}
// Two byte sequence:
elseif (($value & 0xE0) === 0xC0) {
$character = ($value & 0x1F) << 6;
$length = 2;
$remaining = 1;
}
// Three byte sequence:
elseif (($value & 0xF0) === 0xE0) {
$character = ($value & 0x0F) << 12;
$length = 3;
$remaining = 2;
}
// Four byte sequence:
elseif (($value & 0xF8) === 0xF0) {
$character = ($value & 0x07) << 18;
$length = 4;
$remaining = 3;
}
// Invalid byte:
else {
throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $value);
}
if ($remaining > 0) {
if ($position + $length > $strlen) {
throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
}
for ($position++; $remaining > 0; $position++) {
$value = ord($input[$position]);
// If it is invalid, count the sequence as invalid and reprocess the current byte:
if (($value & 0xC0) !== 0x80) {
throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
}
$character |= ($value & 0x3F) << (--$remaining * 6);
}
$position--;
}
if (
// Non-shortest form sequences are invalid
$length > 1 && $character <= 0x7F
|| $length > 2 && $character <= 0x7FF
|| $length > 3 && $character <= 0xFFFF
// Outside of range of ucschar codepoints
// Noncharacters
|| ($character & 0xFFFE) === 0xFFFE
|| $character >= 0xFDD0 && $character <= 0xFDEF
|| (
// Everything else not in ucschar
$character > 0xD7FF && $character < 0xF900
|| $character < 0x20
|| $character > 0x7E && $character < 0xA0
|| $character > 0xEFFFD
)
) {
throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
}
$codepoints[] = $character;
}
return $codepoints;
}
/**
* RFC3492-compliant encoder
*
* @internal Pseudo-code from Section 6.3 is commented with "#" next to relevant code
* @throws Requests_Exception On character outside of the domain (never happens with Punycode) (`idna.character_outside_domain`)
*
* @param string $input UTF-8 encoded string to encode
* @return string Punycode-encoded string
*/
public static function punycode_encode($input) {
$output = '';
# let n = initial_n
$n = self::BOOTSTRAP_INITIAL_N;
# let delta = 0
$delta = 0;
# let bias = initial_bias
$bias = self::BOOTSTRAP_INITIAL_BIAS;
# let h = b = the number of basic code points in the input
$h = $b = 0; // see loop
# copy them to the output in order
$codepoints = self::utf8_to_codepoints($input);
$extended = array();
foreach ($codepoints as $char) {
if ($char < 128) {
// Character is valid ASCII
// TODO: this should also check if it's valid for a URL
$output .= chr($char);
$h++;
}
// Check if the character is non-ASCII, but below initial n
// This never occurs for Punycode, so ignore in coverage
// @codeCoverageIgnoreStart
elseif ($char < $n) {
throw new Requests_Exception('Invalid character', 'idna.character_outside_domain', $char);
}
// @codeCoverageIgnoreEnd
else {
$extended[$char] = true;
}
}
$extended = array_keys($extended);
sort($extended);
$b = $h;
# [copy them] followed by a delimiter if b > 0
if (strlen($output) > 0) {
$output .= '-';
}
# {if the input contains a non-basic code point < n then fail}
# while h < length(input) do begin
while ($h < count($codepoints)) {
# let m = the minimum code point >= n in the input
$m = array_shift($extended);
//printf('next code point to insert is %s' . PHP_EOL, dechex($m));
# let delta = delta + (m - n) * (h + 1), fail on overflow
$delta += ($m - $n) * ($h + 1);
# let n = m
$n = $m;
# for each code point c in the input (in order) do begin
for ($num = 0; $num < count($codepoints); $num++) {
$c = $codepoints[$num];
# if c < n then increment delta, fail on overflow
if ($c < $n) {
$delta++;
}
# if c == n then begin
elseif ($c === $n) {
# let q = delta
$q = $delta;
# for k = base to infinity in steps of base do begin
for ($k = self::BOOTSTRAP_BASE; ; $k += self::BOOTSTRAP_BASE) {
# let t = tmin if k <= bias {+ tmin}, or
# tmax if k >= bias + tmax, or k - bias otherwise
if ($k <= ($bias + self::BOOTSTRAP_TMIN)) {
$t = self::BOOTSTRAP_TMIN;
}
elseif ($k >= ($bias + self::BOOTSTRAP_TMAX)) {
$t = self::BOOTSTRAP_TMAX;
}
else {
$t = $k - $bias;
}
# if q < t then break
if ($q < $t) {
break;
}
# output the code point for digit t + ((q - t) mod (base - t))
$digit = $t + (($q - $t) % (self::BOOTSTRAP_BASE - $t));
$output .= self::digit_to_char($digit);
# let q = (q - t) div (base - t)
$q = floor(($q - $t) / (self::BOOTSTRAP_BASE - $t));
# end
}
# output the code point for digit q
$output .= self::digit_to_char($q);
# let bias = adapt(delta, h + 1, test h equals b?)
$bias = self::adapt($delta, $h + 1, $h === $b);
# let delta = 0
$delta = 0;
# increment h
$h++;
# end
}
# end
}
# increment delta and n
$delta++;
$n++;
# end
}
return $output;
}
/**
* Convert a digit to its respective character
*
* @see https://tools.ietf.org/html/rfc3492#section-5
* @throws Requests_Exception On invalid digit (`idna.invalid_digit`)
*
* @param int $digit Digit in the range 0-35
* @return string Single character corresponding to digit
*/
protected static function digit_to_char($digit) {
// @codeCoverageIgnoreStart
// As far as I know, this never happens, but still good to be sure.
if ($digit < 0 || $digit > 35) {
throw new Requests_Exception(sprintf('Invalid digit %d', $digit), 'idna.invalid_digit', $digit);
}
// @codeCoverageIgnoreEnd
$digits = 'abcdefghijklmnopqrstuvwxyz0123456789';
return substr($digits, $digit, 1);
}
/**
* Adapt the bias
*
* @see https://tools.ietf.org/html/rfc3492#section-6.1
* @param int $delta
* @param int $numpoints
* @param bool $firsttime
* @return int New bias
*/
protected static function adapt($delta, $numpoints, $firsttime) {
# function adapt(delta,numpoints,firsttime):
# if firsttime then let delta = delta div damp
if ($firsttime) {
$delta = floor($delta / self::BOOTSTRAP_DAMP);
}
# else let delta = delta div 2
else {
$delta = floor($delta / 2);
}
# let delta = delta + (delta div numpoints)
$delta += floor($delta / $numpoints);
# let k = 0
$k = 0;
# while delta > ((base - tmin) * tmax) div 2 do begin
$max = floor(((self::BOOTSTRAP_BASE - self::BOOTSTRAP_TMIN) * self::BOOTSTRAP_TMAX) / 2);
while ($delta > $max) {
# let delta = delta div (base - tmin)
$delta = floor($delta / (self::BOOTSTRAP_BASE - self::BOOTSTRAP_TMIN));
# let k = k + base
$k += self::BOOTSTRAP_BASE;
# end
}
# return k + (((base - tmin + 1) * delta) div (delta + skew))
return $k + floor(((self::BOOTSTRAP_BASE - self::BOOTSTRAP_TMIN + 1) * $delta) / ($delta + self::BOOTSTRAP_SKEW));
}
}
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