TemporaryJsonapiFileFieldUploader.php

<?php

namespace Drupal\jsonapi\Controller;

use Drupal\Component\Utility\Bytes;
use Drupal\Component\Utility\Crypt;
use Drupal\Component\Utility\Environment;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Entity\Plugin\DataType\EntityAdapter;
use Drupal\Core\Field\FieldDefinitionInterface;
use Drupal\Core\File\Exception\FileException;
use Drupal\Core\Validation\DrupalTranslator;
use Drupal\file\FileInterface;
use Drupal\Core\File\FileSystemInterface;
use Drupal\Core\Config\ConfigFactoryInterface;
use Drupal\Core\Lock\LockBackendInterface;
use Drupal\Core\Render\BubbleableMetadata;
use Drupal\Core\Session\AccountInterface;
use Drupal\Core\Utility\Token;
use Drupal\Component\Render\PlainTextOutput;
use Drupal\Core\Entity\EntityConstraintViolationList;
use Drupal\file\Entity\File;
use Drupal\file\Plugin\Field\FieldType\FileFieldItemList;
use Psr\Log\LoggerInterface;
use Symfony\Component\HttpFoundation\File\MimeType\MimeTypeGuesserInterface;
use Symfony\Component\HttpKernel\Exception\BadRequestHttpException;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Exception\HttpException;
use Symfony\Component\Validator\ConstraintViolation;

/**
 * Reads data from an upload stream and creates a corresponding file entity.
 *
 * This is implemented at the field level 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 user's field- and
 *     entity-level access.
 *
 * @internal This will be removed once https://www.drupal.org/project/drupal/issues/2940383 lands.
 */
class TemporaryJsonapiFileFieldUploader {
    
    /**
     * 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;
    
    /**
     * A logger instance.
     *
     * @var \Psr\Log\LoggerInterface
     */
    protected $logger;
    
    /**
     * The file system service.
     *
     * @var \Drupal\Core\File\FileSystemInterface
     */
    protected $fileSystem;
    
    /**
     * 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;
    
    /**
     * System file configuration.
     *
     * @var \Drupal\Core\Config\ImmutableConfig
     */
    protected $systemFileConfig;
    
    /**
     * Constructs a FileUploadResource instance.
     *
     * @param \Psr\Log\LoggerInterface $logger
     *   A logger instance.
     * @param \Drupal\Core\File\FileSystemInterface $file_system
     *   The file system service.
     * @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\ConfigFactoryInterface $config_factory
     *   The config factory.
     */
    public function __construct(LoggerInterface $logger, FileSystemInterface $file_system, MimeTypeGuesserInterface $mime_type_guesser, Token $token, LockBackendInterface $lock, ConfigFactoryInterface $config_factory) {
        $this->logger = $logger;
        $this->fileSystem = $file_system;
        $this->mimeTypeGuesser = $mime_type_guesser;
        $this->token = $token;
        $this->lock = $lock;
        $this->systemFileConfig = $config_factory->get('system.file');
    }
    
    /**
     * Creates and validates a file entity for a file field from a file stream.
     *
     * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
     *   The field definition of the field for which the file is to be uploaded.
     * @param string $filename
     *   The name of the file.
     * @param \Drupal\Core\Session\AccountInterface $owner
     *   The owner of the file. Note, it is the responsibility of the caller to
     *   enforce access.
     *
     * @return \Drupal\file\FileInterface|\Drupal\Core\Entity\EntityConstraintViolationListInterface
     *   The newly uploaded file entity, or a list of validation constraint
     *   violations
     *
     * @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 handleFileUploadForField(FieldDefinitionInterface $field_definition, $filename, AccountInterface $owner) {
        assert(is_a($field_definition->getClass(), FileFieldItemList::class, TRUE));
        $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([]);
        $file->setOwnerId($owner->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)) {
            $violations = new EntityConstraintViolationList($file);
            $translator = new DrupalTranslator();
            $entity = EntityAdapter::createFromEntity($file);
            foreach ($errors as $error) {
                $violation = new ConstraintViolation($translator->trans($error), $error, [], $entity, '', NULL);
                $violations->add($violation);
            }
            return $violations;
        }
        $file->setFileUri($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.
        $violations = $file->validate();
        // Remove violations of inaccessible fields as they cannot stem from our
        // changes.
        $violations->filterByFieldAccess();
        if ($violations->count() > 0) {
            return $violations;
        }
        $file->save();
        $this->lock
            ->release($lock_id);
        return $file;
    }
    
    /**
     * 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.
     */
    public function validateAndParseContentDispositionHeader(Request $request) {
        // First, check the header exists.
        if (!$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);
    }
    
    /**
     * Checks if the current user has access to upload the file.
     *
     * @param \Drupal\Core\Session\AccountInterface $account
     *   The account for which file upload access should be checked.
     * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
     *   The field definition for which to get validators.
     * @param \Drupal\Core\Entity\EntityInterface $entity
     *   (optional) The entity to which the file is to be uploaded, if it exists.
     *   If the entity does not exist and it is not given, create access to the
     *   file will be checked.
     *
     * @return \Drupal\Core\Access\AccessResultInterface
     *   The file upload access result.
     */
    public static function checkFileUploadAccess(AccountInterface $account, FieldDefinitionInterface $field_definition, EntityInterface $entity = NULL) {
        assert(is_null($entity) || $field_definition->getTargetEntityTypeId() === $entity->getEntityTypeId() && $field_definition->getTargetBundle() === $entity->bundle());
        $entity_type_manager = \Drupal::entityTypeManager();
        $entity_access_control_handler = $entity_type_manager->getAccessControlHandler($field_definition->getTargetEntityTypeId());
        $bundle = $entity_type_manager->getDefinition($field_definition->getTargetEntityTypeId())
            ->hasKey('bundle') ? $field_definition->getTargetBundle() : NULL;
        $entity_access_result = $entity ? $entity_access_control_handler->access($entity, 'update', $account, TRUE) : $entity_access_control_handler->createAccess($bundle, $account, [], TRUE);
        $field_access_result = $entity_access_control_handler->fieldAccess('edit', $field_definition, NULL, NULL, TRUE);
        return $entity_access_result->andIf($field_access_result);
    }
    
    /**
     * 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 = $this->fileSystem
            ->tempnam('temporary://', 'file');
        if ($temp_file_path === FALSE) {
            $this->logger
                ->error('Temporary file could not be created for file upload.');
            throw new HttpException(500, 'Temporary file could not be created');
        }
        $temp_file = fopen($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 the file.
     *
     * @todo this method is unused in this class because file validation needs to
     *   be split up in 2 steps in ::handleFileUploadForField(). 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().
     *
     * @return \Drupal\Core\Entity\EntityConstraintViolationListInterface
     *   The list of constraint violations, if any.
     */
    protected function validate(FileInterface $file, array $validators) {
        $violations = $file->validate();
        // Remove violations of inaccessible fields as they cannot stem from our
        // changes.
        $violations->filterByFieldAccess();
        // Validate the file based on the field definition configuration.
        $errors = file_validate($file, $validators);
        if (!empty($errors)) {
            $translator = new DrupalTranslator();
            foreach ($errors as $error) {
                $violation = new ConstraintViolation($translator->trans($error), $error, [], EntityAdapter::createFromEntity($file), '', NULL);
                $violations->add($violation);
            }
        }
        return $violations;
    }
    
    /**
     * 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, [], [], new BubbleableMetadata()));
        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;
    }
    
    /**
     * Generates a lock ID based on the file URI.
     *
     * @param string $file_uri
     *   The file URI.
     *
     * @return string
     *   The generated lock ID.
     */
    protected static function generateLockIdFromFileUri($file_uri) {
        return 'file:jsonapi:' . Crypt::hashBase64($file_uri);
    }

}