enwikipedia-acc / waca

includes/Security/TokenManager.php

<?php
/******************************************************************************
 * Wikipedia Account Creation Assistance tool                                 *
 * ACC Development Team. Please see team.json for a list of contributors.     *
 *                                                                            *
 * This is free and unencumbered software released into the public domain.    *
 * Please see LICENSE.md for the full licencing statement.                    *
 ******************************************************************************/

namespace Waca\Security;

use Exception;
use Waca\WebRequest;

class TokenManager
{
    /**
     * Validates a CSRF token
     *
     * @param string      $data    The token data string itself
     * @param string|null $context Token context for extra validation
     *
     * @return bool
     */
    public function validateToken($data, $context = null)
    {
        if (!is_string($data) || strlen($data) === 0) {

The condition is_string($data) is always true.

            // Nothing to validate
            return false;
        }

        $tokens = WebRequest::getSessionTokenData();

        // if the token doesn't exist, then it's not valid
        if (!array_key_exists($data, $tokens)) {
            return false;
        }

        /** @var Token $token */
        $token = unserialize($tokens[$data]);

        if ($token->getTokenData() !== $data) {
            return false;
        }

        if ($token->getContext() !== $context) {
            return false;
        }

        if ($token->isUsed()) {
            return false;
        }

        // mark the token as used, and save it back to the session
        $token->markAsUsed();
        $this->storeToken($token);

        return true;
    }

    /**
     * @param string|null $context An optional context for extra validation
     *
     * @return Token
     */
    public function getNewToken($context = null)
    {
        $token = new Token($this->generateTokenData(), $context);
        $this->storeToken($token);

        return $token;
    }

    /**
     * Stores a token in the session data
     *
     * @param Token $token
     */
    private function storeToken(Token $token)
    {
        $tokens = WebRequest::getSessionTokenData();
        $tokens[$token->getTokenData()] = serialize($token);
        WebRequest::setSessionTokenData($tokens);
    }

    /**
     * Generates a security token
     *
     * @return string
     * @throws Exception
     *
     * @category Security-Critical
     */
    private function generateTokenData()
    {
        $genBytes = openssl_random_pseudo_bytes(33);

        if ($genBytes !== false) {
            return base64_encode($genBytes);
        }

        throw new Exception('Unable to generate secure token.');
    }
}