FileUploadResource.php

<?php

namespace Drupal\file\Plugin\rest\resource;

use Drupal\Component\Utility\Bytes;
use Drupal\Component\Utility\Crypt;
use Drupal\Component\Utility\Environment;
use Drupal\Core\Config\Config;
use Drupal\Core\Entity\EntityTypeManagerInterface;
use Drupal\Core\Field\FieldDefinitionInterface;
use Drupal\Core\File\Exception\FileException;
use Drupal\Core\File\FileSystemInterface;
use Drupal\Core\Lock\LockBackendInterface;
use Drupal\Core\Session\AccountInterface;
use Drupal\Core\Utility\Token;
use Drupal\file\FileInterface;
use Drupal\rest\ModifiedResourceResponse;
use Drupal\rest\Plugin\ResourceBase;
use Drupal\Component\Render\PlainTextOutput;
use Drupal\Core\Entity\EntityFieldManagerInterface;
use Drupal\file\Entity\File;
use Drupal\rest\Plugin\rest\resource\EntityResourceValidationTrait;
use Drupal\rest\RequestHandler;
use Psr\Log\LoggerInterface;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Symfony\Component\HttpFoundation\File\MimeType\MimeTypeGuesserInterface;
use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
use Symfony\Component\HttpKernel\Exception\NotFoundHttpException;
use Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException;
use Symfony\Component\Routing\Route;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Exception\HttpException;

/**
 * File upload resource.
 *
 * This is implemented as a field-level resource for the following reasons:
 *   - Validation for uploaded files is tied to fields (allowed extensions, max
 *     size, etc..).
 *   - The actual files do not need to be stored in another temporary location,
 *     to be later moved when they are referenced from a file field.
 *   - Permission to upload a file can be determined by a users field level
 *     create access to the file field.
 *
 * @RestResource(
 *   id = "file:upload",
 *   label = @Translation("File Upload"),
 *   serialization_class = "Drupal\file\Entity\File",
 *   uri_paths = {
 *     "https://www.drupal.org/link-relations/create" = "/file/upload/{entity_type_id}/{bundle}/{field_name}"
 *   }
 * )
 */
class FileUploadResource extends ResourceBase {
    use EntityResourceValidationTrait {
        validate as resourceValidate;
    }
    
    /**
     * The regex used to extract the filename from the content disposition header.
     *
     * @var string
     */
    const REQUEST_HEADER_FILENAME_REGEX = '@\\bfilename(?<star>\\*?)=\\"(?<filename>.+)\\"@';
    
    /**
     * The amount of bytes to read in each iteration when streaming file data.
     *
     * @var int
     */
    const BYTES_TO_READ = 8192;
    
    /**
     * The file system service.
     *
     * @var \Drupal\Core\File\FileSystem
     */
    protected $fileSystem;
    
    /**
     * The entity type manager.
     *
     * @var \Drupal\Core\Entity\EntityTypeManagerInterface
     */
    protected $entityTypeManager;
    
    /**
     * The entity field manager.
     *
     * @var \Drupal\Core\Entity\EntityFieldManagerInterface
     */
    protected $entityFieldManager;
    
    /**
     * The currently authenticated user.
     *
     * @var \Drupal\Core\Session\AccountInterface
     */
    protected $currentUser;
    
    /**
     * The MIME type guesser.
     *
     * @var \Symfony\Component\HttpFoundation\File\MimeType\MimeTypeGuesserInterface
     */
    protected $mimeTypeGuesser;
    
    /**
     * The token replacement instance.
     *
     * @var \Drupal\Core\Utility\Token
     */
    protected $token;
    
    /**
     * The lock service.
     *
     * @var \Drupal\Core\Lock\LockBackendInterface
     */
    protected $lock;
    
    /**
     * @var \Drupal\Core\Config\ImmutableConfig
     */
    protected $systemFileConfig;
    
    /**
     * Constructs a FileUploadResource instance.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin_id for the plugin instance.
     * @param mixed $plugin_definition
     *   The plugin implementation definition.
     * @param array $serializer_formats
     *   The available serialization formats.
     * @param \Psr\Log\LoggerInterface $logger
     *   A logger instance.
     * @param \Drupal\Core\File\FileSystemInterface $file_system
     *   The file system service.
     * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
     *   The entity type manager.
     * @param \Drupal\Core\Entity\EntityFieldManagerInterface $entity_field_manager
     *   The entity field manager.
     * @param \Drupal\Core\Session\AccountInterface $current_user
     *   The currently authenticated user.
     * @param \Symfony\Component\HttpFoundation\File\MimeType\MimeTypeGuesserInterface $mime_type_guesser
     *   The MIME type guesser.
     * @param \Drupal\Core\Utility\Token $token
     *   The token replacement instance.
     * @param \Drupal\Core\Lock\LockBackendInterface $lock
     *   The lock service.
     * @param \Drupal\Core\Config\Config $system_file_config
     *   The system file configuration.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, $serializer_formats, LoggerInterface $logger, FileSystemInterface $file_system, EntityTypeManagerInterface $entity_type_manager, EntityFieldManagerInterface $entity_field_manager, AccountInterface $current_user, MimeTypeGuesserInterface $mime_type_guesser, Token $token, LockBackendInterface $lock, Config $system_file_config) {
        parent::__construct($configuration, $plugin_id, $plugin_definition, $serializer_formats, $logger);
        $this->fileSystem = $file_system;
        $this->entityTypeManager = $entity_type_manager;
        $this->entityFieldManager = $entity_field_manager;
        $this->currentUser = $current_user;
        $this->mimeTypeGuesser = $mime_type_guesser;
        $this->token = $token;
        $this->lock = $lock;
        $this->systemFileConfig = $system_file_config;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->getParameter('serializer.formats'), $container->get('logger.factory')
            ->get('rest'), $container->get('file_system'), $container->get('entity_type.manager'), $container->get('entity_field.manager'), $container->get('current_user'), $container->get('file.mime_type.guesser'), $container->get('token'), $container->get('lock'), $container->get('config.factory')
            ->get('system.file'));
    }
    
    /**
     * {@inheritdoc}
     */
    public function permissions() {
        // Access to this resource depends on field-level access so no explicit
        // permissions are required.
        // @see \Drupal\file\Plugin\rest\resource\FileUploadResource::validateAndLoadFieldDefinition()
        // @see \Drupal\rest\Plugin\rest\resource\EntityResource::permissions()
        return [];
    }
    
    /**
     * Creates a file from an endpoint.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The current request.
     * @param string $entity_type_id
     *   The entity type ID.
     * @param string $bundle
     *   The entity bundle. This will be the same as $entity_type_id for entity
     *   types that don't support bundles.
     * @param string $field_name
     *   The field name.
     *
     * @return \Drupal\rest\ModifiedResourceResponse
     *   A 201 response, on success.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\HttpException
     *   Thrown when temporary files cannot be written, a lock cannot be acquired,
     *   or when temporary files cannot be moved to their new location.
     */
    public function post(Request $request, $entity_type_id, $bundle, $field_name) {
        $filename = $this->validateAndParseContentDispositionHeader($request);
        $field_definition = $this->validateAndLoadFieldDefinition($entity_type_id, $bundle, $field_name);
        $destination = $this->getUploadLocation($field_definition->getSettings());
        // Check the destination file path is writable.
        if (!$this->fileSystem
            ->prepareDirectory($destination, FileSystemInterface::CREATE_DIRECTORY)) {
            throw new HttpException(500, 'Destination file path is not writable');
        }
        $validators = $this->getUploadValidators($field_definition);
        $prepared_filename = $this->prepareFilename($filename, $validators);
        // Create the file.
        $file_uri = "{$destination}/{$prepared_filename}";
        $temp_file_path = $this->streamUploadData();
        $file_uri = $this->fileSystem
            ->getDestinationFilename($file_uri, FileSystemInterface::EXISTS_RENAME);
        // Lock based on the prepared file URI.
        $lock_id = $this->generateLockIdFromFileUri($file_uri);
        if (!$this->lock
            ->acquire($lock_id)) {
            throw new HttpException(503, sprintf('File "%s" is already locked for writing'), NULL, [
                'Retry-After' => 1,
            ]);
        }
        // Begin building file entity.
        $file = File::create([]);
        $file->setOwnerId($this->currentUser
            ->id());
        $file->setFilename($prepared_filename);
        $file->setMimeType($this->mimeTypeGuesser
            ->guess($prepared_filename));
        $file->setFileUri($temp_file_path);
        // Set the size. This is done in File::preSave() but we validate the file
        // before it is saved.
        $file->setSize(@filesize($temp_file_path));
        // Validate the file against field-level validators first while the file is
        // still a temporary file. Validation is split up in 2 steps to be the same
        // as in _file_save_upload_single().
        // For backwards compatibility this part is copied from ::validate() to
        // leave that method behavior unchanged.
        // @todo Improve this with a file uploader service in
        //   https://www.drupal.org/project/drupal/issues/2940383
        $errors = file_validate($file, $validators);
        if (!empty($errors)) {
            $message = "Unprocessable Entity: file validation failed.\n";
            $message .= implode("\n", array_map([
                PlainTextOutput::class,
                'renderFromHtml',
            ], $errors));
            throw new UnprocessableEntityHttpException($message);
        }
        $file->setFileUri($file_uri);
        // Move the file to the correct location after validation. Use
        // FileSystemInterface::EXISTS_ERROR as the file location has already been
        // determined above in FileSystem::getDestinationFilename().
        try {
            $this->fileSystem
                ->move($temp_file_path, $file_uri, FileSystemInterface::EXISTS_ERROR);
        } catch (FileException $e) {
            throw new HttpException(500, 'Temporary file could not be moved to file location');
        }
        // Second step of the validation on the file object itself now.
        $this->resourceValidate($file);
        $file->save();
        $this->lock
            ->release($lock_id);
        // 201 Created responses return the newly created entity in the response
        // body. These responses are not cacheable, so we add no cacheability
        // metadata here.
        return new ModifiedResourceResponse($file, 201);
    }
    
    /**
     * Streams file upload data to temporary file and moves to file destination.
     *
     * @return string
     *   The temp file path.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\HttpException
     *   Thrown when input data cannot be read, the temporary file cannot be
     *   opened, or the temporary file cannot be written.
     */
    protected function streamUploadData() {
        // 'rb' is needed so reading works correctly on Windows environments too.
        $file_data = fopen('php://input', 'rb');
        $temp_file_path = $this->fileSystem
            ->tempnam('temporary://', 'file');
        $temp_file = fopen($temp_file_path, 'wb');
        if ($temp_file) {
            while (!feof($file_data)) {
                $read = fread($file_data, static::BYTES_TO_READ);
                if ($read === FALSE) {
                    // Close the file streams.
                    fclose($temp_file);
                    fclose($file_data);
                    $this->logger
                        ->error('Input data could not be read');
                    throw new HttpException(500, 'Input file data could not be read');
                }
                if (fwrite($temp_file, $read) === FALSE) {
                    // Close the file streams.
                    fclose($temp_file);
                    fclose($file_data);
                    $this->logger
                        ->error('Temporary file data for "%path" could not be written', [
                        '%path' => $temp_file_path,
                    ]);
                    throw new HttpException(500, 'Temporary file data could not be written');
                }
            }
            // Close the temp file stream.
            fclose($temp_file);
        }
        else {
            // Close the input file stream since we can't proceed with the upload.
            // Don't try to close $temp_file since it's FALSE at this point.
            fclose($file_data);
            $this->logger
                ->error('Temporary file "%path" could not be opened for file upload', [
                '%path' => $temp_file_path,
            ]);
            throw new HttpException(500, 'Temporary file could not be opened');
        }
        // Close the input stream.
        fclose($file_data);
        return $temp_file_path;
    }
    
    /**
     * Validates and extracts the filename from the Content-Disposition header.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request object.
     *
     * @return string
     *   The filename extracted from the header.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
     *   Thrown when the 'Content-Disposition' request header is invalid.
     */
    protected function validateAndParseContentDispositionHeader(Request $request) {
        // Firstly, check the header exists.
        if (!$request->headers
            ->has('content-disposition')) {
            throw new BadRequestHttpException('"Content-Disposition" header is required. A file name in the format "filename=FILENAME" must be provided');
        }
        $content_disposition = $request->headers
            ->get('content-disposition');
        // Parse the header value. This regex does not allow an empty filename.
        // i.e. 'filename=""'. This also matches on a word boundary so other keys
        // like 'not_a_filename' don't work.
        if (!preg_match(static::REQUEST_HEADER_FILENAME_REGEX, $content_disposition, $matches)) {
            throw new BadRequestHttpException('No filename found in "Content-Disposition" header. A file name in the format "filename=FILENAME" must be provided');
        }
        // Check for the "filename*" format. This is currently unsupported.
        if (!empty($matches['star'])) {
            throw new BadRequestHttpException('The extended "filename*" format is currently not supported in the "Content-Disposition" header');
        }
        // Don't validate the actual filename here, that will be done by the upload
        // validators in validate().
        // @see \Drupal\file\Plugin\rest\resource\FileUploadResource::validate()
        $filename = $matches['filename'];
        // Make sure only the filename component is returned. Path information is
        // stripped as per https://tools.ietf.org/html/rfc6266#section-4.3.
        return $this->fileSystem
            ->basename($filename);
    }
    
    /**
     * Validates and loads a field definition instance.
     *
     * @param string $entity_type_id
     *   The entity type ID the field is attached to.
     * @param string $bundle
     *   The bundle the field is attached to.
     * @param string $field_name
     *   The field name.
     *
     * @return \Drupal\Core\Field\FieldDefinitionInterface
     *   The field definition.
     *
     * @throws \Symfony\Component\HttpKernel\Exception\BadRequestHttpException
     *   Thrown when the field does not exist.
     * @throws \Symfony\Component\HttpFoundation\File\Exception\AccessDeniedException
     *   Thrown when the target type of the field is not a file, or the current
     *   user does not have 'edit' access for the field.
     */
    protected function validateAndLoadFieldDefinition($entity_type_id, $bundle, $field_name) {
        $field_definitions = $this->entityFieldManager
            ->getFieldDefinitions($entity_type_id, $bundle);
        if (!isset($field_definitions[$field_name])) {
            throw new NotFoundHttpException(sprintf('Field "%s" does not exist', $field_name));
        }
        
        /** @var \Drupal\Core\Field\FieldDefinitionInterface $field_definition */
        $field_definition = $field_definitions[$field_name];
        if ($field_definition->getSetting('target_type') !== 'file') {
            throw new AccessDeniedHttpException(sprintf('"%s" is not a file field', $field_name));
        }
        $entity_access_control_handler = $this->entityTypeManager
            ->getAccessControlHandler($entity_type_id);
        $bundle = $this->entityTypeManager
            ->getDefinition($entity_type_id)
            ->hasKey('bundle') ? $bundle : NULL;
        $access_result = $entity_access_control_handler->createAccess($bundle, NULL, [], TRUE)
            ->andIf($entity_access_control_handler->fieldAccess('edit', $field_definition, NULL, NULL, TRUE));
        if (!$access_result->isAllowed()) {
            throw new AccessDeniedHttpException($access_result->getReason());
        }
        return $field_definition;
    }
    
    /**
     * Validates the file.
     *
     * @todo this method is unused in this class because file validation needs to
     *   be split up in 2 steps in ::post(). Add a deprecation notice as soon as a
     *   central core file upload service can be used in this class.
     *   See https://www.drupal.org/project/drupal/issues/2940383
     *
     * @param \Drupal\file\FileInterface $file
     *   The file entity to validate.
     * @param array $validators
     *   An array of upload validators to pass to file_validate().
     *
     * @throws \Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException
     *   Thrown when there are file validation errors.
     */
    protected function validate(FileInterface $file, array $validators) {
        $this->resourceValidate($file);
        // Validate the file based on the field definition configuration.
        $errors = file_validate($file, $validators);
        if (!empty($errors)) {
            $message = "Unprocessable Entity: file validation failed.\n";
            $message .= implode("\n", array_map(function ($error) {
                return PlainTextOutput::renderFromHtml($error);
            }, $errors));
            throw new UnprocessableEntityHttpException($message);
        }
    }
    
    /**
     * Prepares the filename to strip out any malicious extensions.
     *
     * @param string $filename
     *   The file name.
     * @param array $validators
     *   The array of upload validators.
     *
     * @return string
     *   The prepared/munged filename.
     */
    protected function prepareFilename($filename, array &$validators) {
        // Don't rename if 'allow_insecure_uploads' evaluates to TRUE.
        if (!$this->systemFileConfig
            ->get('allow_insecure_uploads')) {
            if (!empty($validators['file_validate_extensions'][0])) {
                // If there is a file_validate_extensions validator and a list of
                // valid extensions, munge the filename to protect against possible
                // malicious extension hiding within an unknown file type. For example,
                // "filename.html.foo".
                $filename = file_munge_filename($filename, $validators['file_validate_extensions'][0]);
            }
            // Rename potentially executable files, to help prevent exploits (i.e.
            // will rename filename.php.foo and filename.php to filename._php._foo.txt
            // and filename._php.txt, respectively).
            if (preg_match(FILE_INSECURE_EXTENSION_REGEX, $filename)) {
                // If the file will be rejected anyway due to a disallowed extension, it
                // should not be renamed; rather, we'll let file_validate_extensions()
                // reject it below.
                $passes_validation = FALSE;
                if (!empty($validators['file_validate_extensions'][0])) {
                    $file = File::create([]);
                    $file->setFilename($filename);
                    $passes_validation = empty(file_validate_extensions($file, $validators['file_validate_extensions'][0]));
                }
                if (empty($validators['file_validate_extensions'][0]) || $passes_validation) {
                    if (substr($filename, -4) != '.txt') {
                        // The destination filename will also later be used to create the URI.
                        $filename .= '.txt';
                    }
                    $filename = file_munge_filename($filename, $validators['file_validate_extensions'][0] ?? '');
                    // The .txt extension may not be in the allowed list of extensions. We
                    // have to add it here or else the file upload will fail.
                    if (!empty($validators['file_validate_extensions'][0])) {
                        $validators['file_validate_extensions'][0] .= ' txt';
                    }
                }
            }
        }
        return $filename;
    }
    
    /**
     * Determines the URI for a file field.
     *
     * @param array $settings
     *   The array of field settings.
     *
     * @return string
     *   An un-sanitized file directory URI with tokens replaced. The result of
     *   the token replacement is then converted to plain text and returned.
     */
    protected function getUploadLocation(array $settings) {
        $destination = trim($settings['file_directory'], '/');
        // Replace tokens. As the tokens might contain HTML we convert it to plain
        // text.
        $destination = PlainTextOutput::renderFromHtml($this->token
            ->replace($destination, []));
        return $settings['uri_scheme'] . '://' . $destination;
    }
    
    /**
     * Retrieves the upload validators for a field definition.
     *
     * This is copied from \Drupal\file\Plugin\Field\FieldType\FileItem as there
     * is no entity instance available here that a FileItem would exist for.
     *
     * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
     *   The field definition for which to get validators.
     *
     * @return array
     *   An array suitable for passing to file_save_upload() or the file field
     *   element's '#upload_validators' property.
     */
    protected function getUploadValidators(FieldDefinitionInterface $field_definition) {
        $validators = [
            // Add in our check of the file name length.
'file_validate_name_length' => [],
        ];
        $settings = $field_definition->getSettings();
        // Cap the upload size according to the PHP limit.
        $max_filesize = Bytes::toInt(Environment::getUploadMaxSize());
        if (!empty($settings['max_filesize'])) {
            $max_filesize = min($max_filesize, Bytes::toInt($settings['max_filesize']));
        }
        // There is always a file size limit due to the PHP server limit.
        $validators['file_validate_size'] = [
            $max_filesize,
        ];
        // Add the extension check if necessary.
        if (!empty($settings['file_extensions'])) {
            $validators['file_validate_extensions'] = [
                $settings['file_extensions'],
            ];
        }
        return $validators;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getBaseRoute($canonical_path, $method) {
        return new Route($canonical_path, [
            '_controller' => RequestHandler::class . '::handleRaw',
        ], $this->getBaseRouteRequirements($method), [], '', [], [
            $method,
        ]);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getBaseRouteRequirements($method) {
        $requirements = parent::getBaseRouteRequirements($method);
        // Add the content type format access check. This will enforce that all
        // incoming requests can only use the 'application/octet-stream'
        // Content-Type header.
        $requirements['_content_type_format'] = 'bin';
        return $requirements;
    }
    
    /**
     * Generates a lock ID based on the file URI.
     *
     * @param $file_uri
     *   The file URI.
     *
     * @return string
     *   The generated lock ID.
     */
    protected static function generateLockIdFromFileUri($file_uri) {
        return 'file:rest:' . Crypt::hashBase64($file_uri);
    }

}