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<?php |
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declare(strict_types=1); |
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/** |
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* This file is part of the Linna Csrf Guard. |
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* |
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* @author Sebastian Rapetti <[email protected]> |
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* @copyright (c) 2020, Sebastian Rapetti |
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* @license http://opensource.org/licenses/MIT MIT License |
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*/ |
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namespace Linna\CsrfGuard\Provider; |
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use Linna\CsrfGuard\Exception\BadExpireException; |
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use Linna\CsrfGuard\Exception\BadStorageSizeException; |
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use Linna\CsrfGuard\Exception\BadTokenLengthException; |
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use Linna\CsrfGuard\Exception\BadExpireTrait; |
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use Linna\CsrfGuard\Exception\BadStorageSizeTrait; |
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use Linna\CsrfGuard\Exception\BadTokenLengthTrait; |
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use Linna\CsrfGuard\Exception\SessionNotStartedException; |
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use Linna\CsrfGuard\Exception\SessionNotStartedTrait; |
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/** |
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* Syncronizer token provider. |
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* |
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* <p>A random token with the expire time in this type of tokek, the token with the time are stored in session but only |
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* the token is returned.</p> |
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* |
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* <p> |
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* The difficulty about guess the token is proportional to his length, the formula is <code>1/16^(token_length*2)</code>. |
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* Using a token of 16 byte means <code>1/16^(16*2)</code>, <code>1/16^32</code>.<br/>Who tray to guess the token has |
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* a possibility of <code>1/(a number greater than the number of atoms in universe)<code/>. |
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* </p> |
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*/ |
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class SynchronizerTokenProvider implements TokenProviderInterface |
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{ |
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use BadExpireTrait; |
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use BadStorageSizeTrait; |
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use BadTokenLengthTrait; |
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use SessionNotStartedTrait; |
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/** @var string CSRF_TOKEN_STORAGE Token storage key name in session array. */ |
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private const CSRF_TOKEN_STORAGE = 'csrf_syncronizer_token'; |
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/** |
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* Class constructor. |
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* |
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* @param int $expire Token validity in seconds, default 600 -> 10 minutes. |
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* @param int $storageSize Maximum token nonces stored in session. |
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* @param int $tokenLength The desidered token length in bytes, consider that the time is added to the token. |
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* |
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* @throws BadExpireException If <code>$expire</code> is less than 0 and greater than 86400. |
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* @throws BadStorageSizeException If <code>$storageSize</code> is less than 2 and greater than 64. |
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* @throws BadTokenLengthException If <code>$tokenLength</code> is less than 16 and greater than 128. |
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*/ |
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public function __construct( |
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/** @var int $expire Token validity in seconds, default 600 -> 10 minutes. */ |
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private int $expire = 600, |
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/** @var int $tokenLength Token length in chars. */ |
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private int $storageSize = 10, |
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/** @var int $storageSize Maximum token nonces stored in session. */ |
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private int $tokenLength = 32 |
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) { |
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// from BadExpireTrait, BadStorageSizeTrait, BadTokenLengthException and SessionNotStartedTrait |
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/** @throws BadExpireException */ |
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$this->checkBadExpire($expire); |
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/** @throws BadStorageSizeException */ |
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$this->checkBadStorageSize($storageSize); |
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/** @throws BadTokenLengthException */ |
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$this->checkBadTokenLength($tokenLength); |
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/** @throws SessionNotStartedException */ |
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$this->checkSessionNotStarted(); |
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$this->expire = $expire; |
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$this->tokenLength = $tokenLength; |
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$this->storageSize = $storageSize; |
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//if any token stored, initialize the session storage |
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$_SESSION[self::CSRF_TOKEN_STORAGE] ??= []; |
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} |
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/** |
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* Return new Synchronizer based Token. |
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* |
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* @return string The token in hex format. |
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*/ |
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public function getToken(): string |
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{ |
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//generate new token |
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$token = \bin2hex(\random_bytes(\max(1, $this->tokenLength))); |
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$time = \dechex(\time()); |
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//store new token |
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$_SESSION[self::CSRF_TOKEN_STORAGE][] = $token.$time; |
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//check if the storage is growt beyond the maximun size |
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if (\count($_SESSION[self::CSRF_TOKEN_STORAGE]) > $this->storageSize) { |
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//remove the oldest stores nonce |
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\array_shift($_SESSION[self::CSRF_TOKEN_STORAGE]); |
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} |
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return $token; |
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} |
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/** |
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* Validate Synchronizer based Token. |
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* |
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* @param string $token Token must be validated, hex format. |
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* |
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* @return bool True if the token is valid, false otherwise. |
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*/ |
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public function validate(string $token): bool |
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{ |
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//reference to token storage in session |
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$tokens = &$_SESSION[self::CSRF_TOKEN_STORAGE]; |
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//get current size of token storage in session |
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$size = \count($tokens); |
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//bytes to b16 chars |
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$chars = $this->tokenLength * 2; |
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//current time |
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$time = \time(); |
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for ($i = $size -1; $i > -1; $i--) { |
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//get token from storage |
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//if token in storage doesn't match user token continue |
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if (($tmpToken = \substr($tokens[$i], 0, $chars)) !== $token) { |
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continue; |
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} |
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//get time from storage |
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//subtract the length of the token to the token+time |
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$tmpTime = \substr($tokens[$i], $chars); |
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//timestamp from token time |
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$timestamp = \hexdec($tmpTime); |
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//token expiration check |
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if (($timestamp + $this->expire) >= $time) { |
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return true; |
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} |
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//remove token expired from session |
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unset($tokens[$i]); |
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} |
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return false; |
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} |
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} |
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linna /
csrf-guard
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