firefly-iii/app/Http/Middleware/AcceptHeaders.php

<?php

/*
 * AcceptHeaders.php
 * Copyright (c) 2022 james@firefly-iii.org
 *
 * This file is part of Firefly III (https://github.com/firefly-iii).
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

declare(strict_types=1);

namespace FireflyIII\Http\Middleware;

use FireflyIII\Exceptions\BadHttpHeaderException;
use Illuminate\Http\Request;
use Illuminate\Http\Response;
use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;

/**
 *
 */
class AcceptHeaders
{
    /**
     * Handle the incoming requests.
     *
     * @param Request  $request
     * @param callable $next
     * @return Response
     * @throws BadHttpHeaderException
     */
    public function handle(Request $request, callable $next): mixed
    {
        $method       = $request->getMethod();
        $accepts      = ['application/x-www-form-urlencoded', 'application/json', 'application/vnd.api+json', 'application/octet-stream', '*/*'];
        $contentTypes = ['application/x-www-form-urlencoded', 'application/json', 'application/vnd.api+json', 'application/octet-stream'];
        $submitted    = (string)$request->header('Content-Type');


        // if bad Accept header, send error.
        if (!$request->accepts($accepts)) {
            throw new BadHttpHeaderException(sprintf('Accept header "%s" is not something this server can provide.', $request->header('Accept')));
        }
        // if bad 'Content-Type' header, refuse service.
        if (('POST' === $method || 'PUT' === $method) && !$request->hasHeader('Content-Type')) {
            $error             = new BadHttpHeaderException('Content-Type header cannot be empty.');
            $error->statusCode = 415;
            throw $error;
        }
        if (('POST' === $method || 'PUT' === $method) && !$this->acceptsHeader($submitted, $contentTypes)) {
            $error             = new BadHttpHeaderException(sprintf('Content-Type cannot be "%s"', $submitted));
            $error->statusCode = 415;
            throw $error;
        }

        // throw bad request if trace id is not a UUID
        $uuid = $request->header('X-Trace-Id');
        if (is_string($uuid) && '' !== trim($uuid) && (preg_match('/^[a-f\d]{8}(-[a-f\d]{4}){4}[a-f\d]{8}$/i', trim($uuid)) !== 1)) {
            throw new BadRequestHttpException('Bad X-Trace-Id header.');
        }

        return $next($request);
    }

    /**
     * @param string $content
     * @param array  $accepted
     * @return bool
     */
    private function acceptsHeader(string $content, array $accepted): bool
    {
        if (str_contains($content, ';')) {
            $content = trim(explode(';', $content)[0]);
        }
        return in_array($content, $accepted, true);
    }
}