File: docs/files/Token.php.txt

<?php

namespace PhpApi;

/**
 * This class implements a token resoruce. A file named 'keys.json' should
 * host all token keys that will be accepted by the project.
 * 
 * {
 *  "SystemName": "token_string_123456",
 *  "AnotherSystem": "token_string_654321"
 * }
 * 
 * @package PhpApi
 * @copyright (c) 2017, Federal Institute of Rondonia
 * @license http://gnu.org/licenses/lgpl.txt LGPL-3.0+
 * @author Natanael Simoes <natanael.simoes@ifro.edu.br>
 * @since Release 0.1.0
 * @link https://github.com/ifroariquemes/PHP-API Github repository
 */
class Token
{

    use \FlorianWolters\Component\Util\Singleton\SingletonTrait;

    /**
     * The path to the token keys file (should be at project root)
     */
    const KEYS_PATH = './keys.json';

    /**
     * The header option that contains the API key
     */
    const KEY_INDEX = 'HTTP_X_API_KEY';

    /**
     * Checks if the keys.json contains the API key sent at HTTP header.
     * If keys.json does not exists at project root, then token security
     * will not be used.
     * @return bool Authenticated successfully
     */
    public static function authenticate(): bool
    {
        if (file_exists(self::KEYS_PATH)) {
            $keys = (array) json_decode(file_get_contents(self::KEYS_PATH));
            $token = filter_input(INPUT_SERVER, self::KEY_INDEX);
            if (!in_array($token, $keys)) {
                http_response_code(401);
                echo json_encode(['message' => 'Invalid token.']);
                exit;
            }
        }
        return true;
    }

}