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