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PhpSessionSerializer.php
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PhpSessionSerializer.php
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<?php
/**
* Wikimedia\PhpSessionSerializer
*
* Copyright (C) 2015 Brad Jorsch <bjorsch@wikimedia.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
* http://www.gnu.org/copyleft/gpl.html
*
* @file
* @author Brad Jorsch <bjorsch@wikimedia.org>
*/
namespace Wikimedia;
use DomainException;
use Exception;
use InvalidArgumentException;
use Psr\Log\LoggerInterface;
use UnexpectedValueException;
/**
* Provides for encoding and decoding session arrays to PHP's serialization
* formats.
*
* Supported formats are:
* - php
* - php_binary
* - php_serialize
*
* WDDX is not supported, since it breaks on all sorts of things.
*/
class PhpSessionSerializer {
/** @var LoggerInterface */
protected static $logger;
/**
* Set the logger to which to log
* @param LoggerInterface $logger The logger
*/
public static function setLogger( LoggerInterface $logger ) {
self::$logger = $logger;
}
/**
* Try to set session.serialize_handler to a supported format
*
* This may change the format even if the current format is also supported.
*
* @return string Format set
* @throws DomainException
*/
public static function setSerializeHandler() {
$formats = [
'php_serialize',
'php',
'php_binary',
];
// First, try php_serialize since that's the only one that doesn't suck in some way.
// phpcs:ignore Generic.PHP.NoSilencedErrors.Discouraged
@ini_set( 'session.serialize_handler', 'php_serialize' );
if ( ini_get( 'session.serialize_handler' ) === 'php_serialize' ) {
return 'php_serialize';
}
// Next, just use the current format if it's supported.
$format = ini_get( 'session.serialize_handler' );
if ( in_array( $format, $formats, true ) ) {
return $format;
}
// Last chance, see if any of our supported formats are accepted.
foreach ( $formats as $format ) {
// phpcs:ignore Generic.PHP.NoSilencedErrors.Discouraged
@ini_set( 'session.serialize_handler', $format );
if ( ini_get( 'session.serialize_handler' ) === $format ) {
return $format;
}
}
throw new DomainException(
'Failed to set serialize handler to a supported format.' .
' Supported formats are: ' . implode( ', ', $formats ) . '.'
);
}
/**
* Encode a session array to a string, using the format in session.serialize_handler
* @param array $data Session data
* @return string|null Encoded string, or null on failure
* @throws DomainException
*/
public static function encode( array $data ) {
$format = ini_get( 'session.serialize_handler' );
if ( !is_string( $format ) ) {
throw new UnexpectedValueException(
'Could not fetch the value of session.serialize_handler'
);
}
switch ( $format ) {
case 'php':
return self::encodePhp( $data );
case 'php_binary':
return self::encodePhpBinary( $data );
case 'php_serialize':
return self::encodePhpSerialize( $data );
default:
throw new DomainException( "Unsupported format \"$format\"" );
}
}
/**
* Decode a session string to an array, using the format in session.serialize_handler
* @param string $data Session data. Use the same caution in passing
* user-controlled data here that you would to PHP's unserialize function.
* @return array|null Data, or null on failure
* @throws DomainException
* @throws InvalidArgumentException
*/
public static function decode( $data ) {
if ( !is_string( $data ) ) {
throw new InvalidArgumentException( '$data must be a string' );
}
$format = ini_get( 'session.serialize_handler' );
if ( !is_string( $format ) ) {
throw new UnexpectedValueException(
'Could not fetch the value of session.serialize_handler'
);
}
switch ( $format ) {
case 'php':
return self::decodePhp( $data );
case 'php_binary':
return self::decodePhpBinary( $data );
case 'php_serialize':
return self::decodePhpSerialize( $data );
default:
throw new DomainException( "Unsupported format \"$format\"" );
}
}
/**
* Serialize a value with error logging
* @param mixed $value
* @return string|null
*/
private static function serializeValue( $value ) {
try {
return serialize( $value );
} catch ( Exception $ex ) {
self::$logger->error( 'Value serialization failed: ' . $ex->getMessage() );
return null;
}
}
/**
* Unserialize a value with error logging
* @param string &$string On success, the portion used is removed
* @return array ( bool $success, mixed $value )
*/
private static function unserializeValue( &$string ) {
$error = null;
set_error_handler( static function ( $errno, $errstr ) use ( &$error ) {
$error = $errstr;
return true;
} );
$ret = unserialize( $string );
restore_error_handler();
if ( $error !== null ) {
self::$logger->error( 'Value unserialization failed: ' . $error );
return [ false, null ];
}
$serialized = serialize( $ret );
$l = strlen( $serialized );
if ( substr( $string, 0, $l ) !== $serialized ) {
self::$logger->error(
'Value unserialization failed: read value does not match original string'
);
return [ false, null ];
}
$string = substr( $string, $l );
return [ true, $ret ];
}
/**
* Encode a session array to a string in 'php' format
* @note Generally you'll use self::encode() instead of this method.
* @param array $data Session data
* @return string|null Encoded string, or null on failure
*/
public static function encodePhp( array $data ) {
$ret = '';
foreach ( $data as $key => $value ) {
// @phan-suppress-next-line PhanTypeMismatchArgumentInternal
if ( strcmp( $key, intval( $key ) ) === 0 ) {
self::$logger->warning( "Ignoring unsupported integer key \"$key\"" );
continue;
}
if ( strcspn( $key, '|!' ) !== strlen( $key ) ) {
self::$logger->error( "Serialization failed: Key with unsupported characters \"$key\"" );
return null;
}
$v = self::serializeValue( $value );
if ( $v === null ) {
return null;
}
$ret .= "$key|$v";
}
return $ret;
}
/**
* Decode a session string in 'php' format to an array
* @note Generally you'll use self::decode() instead of this method.
* @param string $data Session data. Use the same caution in passing
* user-controlled data here that you would to PHP's unserialize function.
* @return array|null Data, or null on failure
* @throws InvalidArgumentException
*/
public static function decodePhp( $data ) {
if ( !is_string( $data ) ) {
throw new InvalidArgumentException( '$data must be a string' );
}
$ret = [];
while ( $data !== '' && $data !== false ) {
$i = strpos( $data, '|' );
if ( $i === false ) {
if ( substr( $data, -1 ) !== '!' ) {
self::$logger->warning( 'Ignoring garbage at end of string' );
}
break;
}
$key = substr( $data, 0, $i );
$data = substr( $data, $i + 1 );
if ( strpos( $key, '!' ) !== false ) {
self::$logger->warning( "Decoding found a key with unsupported characters: \"$key\"" );
}
if ( $data === '' || $data === false ) {
self::$logger->error( 'Unserialize failed: unexpected end of string' );
return null;
}
[ $ok, $value ] = self::unserializeValue( $data );
if ( !$ok ) {
return null;
}
$ret[$key] = $value;
}
return $ret;
}
/**
* Encode a session array to a string in 'php_binary' format
* @note Generally you'll use self::encode() instead of this method.
* @param array $data Session data
* @return string|null Encoded string, or null on failure
*/
public static function encodePhpBinary( array $data ) {
$ret = '';
foreach ( $data as $key => $value ) {
// @phan-suppress-next-line PhanTypeMismatchArgumentInternal
if ( strcmp( $key, intval( $key ) ) === 0 ) {
self::$logger->warning( "Ignoring unsupported integer key \"$key\"" );
continue;
}
$l = strlen( $key );
if ( $l > 127 ) {
self::$logger->warning( "Ignoring overlong key \"$key\"" );
continue;
}
$v = self::serializeValue( $value );
if ( $v === null ) {
return null;
}
$ret .= chr( $l ) . $key . $v;
}
return $ret;
}
/**
* Decode a session string in 'php_binary' format to an array
* @note Generally you'll use self::decode() instead of this method.
* @param string $data Session data. Use the same caution in passing
* user-controlled data here that you would to PHP's unserialize function.
* @return array|null Data, or null on failure
* @throws InvalidArgumentException
*/
public static function decodePhpBinary( $data ) {
if ( !is_string( $data ) ) {
throw new InvalidArgumentException( '$data must be a string' );
}
$ret = [];
while ( $data !== '' && $data !== false ) {
$l = ord( $data[0] );
if ( strlen( $data ) < ( $l & 127 ) + 1 ) {
self::$logger->error( 'Unserialize failed: unexpected end of string' );
return null;
}
// "undefined" marker
if ( $l > 127 ) {
$data = substr( $data, ( $l & 127 ) + 1 );
continue;
}
$key = substr( $data, 1, $l );
$data = substr( $data, $l + 1 );
if ( $data === '' || $data === false ) {
self::$logger->error( 'Unserialize failed: unexpected end of string' );
return null;
}
[ $ok, $value ] = self::unserializeValue( $data );
if ( !$ok ) {
return null;
}
$ret[$key] = $value;
}
return $ret;
}
/**
* Encode a session array to a string in 'php_serialize' format
* @note Generally you'll use self::encode() instead of this method.
* @param array $data Session data
* @return string|null Encoded string, or null on failure
*/
public static function encodePhpSerialize( array $data ) {
try {
return serialize( $data );
} catch ( Exception $ex ) {
self::$logger->error( 'PHP serialization failed: ' . $ex->getMessage() );
return null;
}
}
/**
* Decode a session string in 'php_serialize' format to an array
* @note Generally you'll use self::decode() instead of this method.
* @param string $data Session data. Use the same caution in passing
* user-controlled data here that you would to PHP's unserialize function.
* @return array|null Data, or null on failure
* @throws InvalidArgumentException
*/
public static function decodePhpSerialize( $data ) {
if ( !is_string( $data ) ) {
throw new InvalidArgumentException( '$data must be a string' );
}
$error = null;
set_error_handler( static function ( $errno, $errstr ) use ( &$error ) {
$error = $errstr;
return true;
} );
$ret = unserialize( $data );
restore_error_handler();
if ( $error !== null ) {
self::$logger->error( 'PHP unserialization failed: ' . $error );
return null;
}
// PHP strangely allows non-arrays to session_decode(), even though
// that breaks $_SESSION. Let's not do that.
if ( !is_array( $ret ) ) {
self::$logger->error( 'PHP unserialization failed (value was not an array)' );
return null;
}
return $ret;
}
}
PhpSessionSerializer::setLogger( new \Psr\Log\NullLogger() ); // @codeCoverageIgnore

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Mime Type
text/x-php
Expires
Aug 19 2026, 19:48 (6 w, 6 d ago)
Storage Engine
local-disk
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Storage Handle
46/3b/24b5570400e5625d72f687b4c33b
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PhpSessionSerializer.php (11 KB)

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