From b312769c0ee2c40b1a26a6ed39ea1c8a462d4349 Mon Sep 17 00:00:00 2001 From: Patrick Cloke Date: Wed, 9 Sep 2020 12:59:41 -0400 Subject: [PATCH] Do not error when thumbnailing invalid files (#8236) If a file cannot be thumbnailed for some reason (e.g. the file is empty), then catch the exception and convert it to a reasonable error message for the client. --- changelog.d/8236.bugfix | 1 + synapse/rest/media/v1/media_repository.py | 69 ++++++++++++++++++--- synapse/rest/media/v1/thumbnail_resource.py | 5 +- synapse/rest/media/v1/thumbnailer.py | 14 ++++- tests/rest/media/v1/test_media_storage.py | 41 ++++++++---- 5 files changed, 107 insertions(+), 23 deletions(-) create mode 100644 changelog.d/8236.bugfix diff --git a/changelog.d/8236.bugfix b/changelog.d/8236.bugfix new file mode 100644 index 0000000000..6f04871015 --- /dev/null +++ b/changelog.d/8236.bugfix @@ -0,0 +1 @@ +Fix a longstanding bug where files that could not be thumbnailed would result in an Internal Server Error. diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py index 9a1b7779f7..69f353d46f 100644 --- a/synapse/rest/media/v1/media_repository.py +++ b/synapse/rest/media/v1/media_repository.py @@ -53,7 +53,7 @@ from .media_storage import MediaStorage from .preview_url_resource import PreviewUrlResource from .storage_provider import StorageProviderWrapper from .thumbnail_resource import ThumbnailResource -from .thumbnailer import Thumbnailer +from .thumbnailer import Thumbnailer, ThumbnailError from .upload_resource import UploadResource logger = logging.getLogger(__name__) @@ -460,13 +460,30 @@ class MediaRepository: return t_byte_source async def generate_local_exact_thumbnail( - self, media_id, t_width, t_height, t_method, t_type, url_cache - ): + self, + media_id: str, + t_width: int, + t_height: int, + t_method: str, + t_type: str, + url_cache: str, + ) -> Optional[str]: input_path = await self.media_storage.ensure_media_is_in_local_cache( FileInfo(None, media_id, url_cache=url_cache) ) - thumbnailer = Thumbnailer(input_path) + try: + thumbnailer = Thumbnailer(input_path) + except ThumbnailError as e: + logger.warning( + "Unable to generate a thumbnail for local media %s using a method of %s and type of %s: %s", + media_id, + t_method, + t_type, + e, + ) + return None + t_byte_source = await defer_to_thread( self.hs.get_reactor(), self._generate_thumbnail, @@ -506,14 +523,36 @@ class MediaRepository: return output_path + # Could not generate thumbnail. + return None + async def generate_remote_exact_thumbnail( - self, server_name, file_id, media_id, t_width, t_height, t_method, t_type - ): + self, + server_name: str, + file_id: str, + media_id: str, + t_width: int, + t_height: int, + t_method: str, + t_type: str, + ) -> Optional[str]: input_path = await self.media_storage.ensure_media_is_in_local_cache( FileInfo(server_name, file_id, url_cache=False) ) - thumbnailer = Thumbnailer(input_path) + try: + thumbnailer = Thumbnailer(input_path) + except ThumbnailError as e: + logger.warning( + "Unable to generate a thumbnail for remote media %s from %s using a method of %s and type of %s: %s", + media_id, + server_name, + t_method, + t_type, + e, + ) + return None + t_byte_source = await defer_to_thread( self.hs.get_reactor(), self._generate_thumbnail, @@ -559,6 +598,9 @@ class MediaRepository: return output_path + # Could not generate thumbnail. + return None + async def _generate_thumbnails( self, server_name: Optional[str], @@ -590,7 +632,18 @@ class MediaRepository: FileInfo(server_name, file_id, url_cache=url_cache) ) - thumbnailer = Thumbnailer(input_path) + try: + thumbnailer = Thumbnailer(input_path) + except ThumbnailError as e: + logger.warning( + "Unable to generate thumbnails for remote media %s from %s using a method of %s and type of %s: %s", + media_id, + server_name, + media_type, + e, + ) + return None + m_width = thumbnailer.width m_height = thumbnailer.height diff --git a/synapse/rest/media/v1/thumbnail_resource.py b/synapse/rest/media/v1/thumbnail_resource.py index a83535b97b..30421b663a 100644 --- a/synapse/rest/media/v1/thumbnail_resource.py +++ b/synapse/rest/media/v1/thumbnail_resource.py @@ -16,6 +16,7 @@ import logging +from synapse.api.errors import SynapseError from synapse.http.server import DirectServeJsonResource, set_cors_headers from synapse.http.servlet import parse_integer, parse_string @@ -173,7 +174,7 @@ class ThumbnailResource(DirectServeJsonResource): await respond_with_file(request, desired_type, file_path) else: logger.warning("Failed to generate thumbnail") - respond_404(request) + raise SynapseError(400, "Failed to generate thumbnail.") async def _select_or_generate_remote_thumbnail( self, @@ -235,7 +236,7 @@ class ThumbnailResource(DirectServeJsonResource): await respond_with_file(request, desired_type, file_path) else: logger.warning("Failed to generate thumbnail") - respond_404(request) + raise SynapseError(400, "Failed to generate thumbnail.") async def _respond_remote_thumbnail( self, request, server_name, media_id, width, height, method, m_type diff --git a/synapse/rest/media/v1/thumbnailer.py b/synapse/rest/media/v1/thumbnailer.py index d681bf7bf0..457ad6031c 100644 --- a/synapse/rest/media/v1/thumbnailer.py +++ b/synapse/rest/media/v1/thumbnailer.py @@ -15,7 +15,7 @@ import logging from io import BytesIO -from PIL import Image as Image +from PIL import Image logger = logging.getLogger(__name__) @@ -31,12 +31,22 @@ EXIF_TRANSPOSE_MAPPINGS = { } +class ThumbnailError(Exception): + """An error occurred generating a thumbnail.""" + + class Thumbnailer: FORMATS = {"image/jpeg": "JPEG", "image/png": "PNG"} def __init__(self, input_path): - self.image = Image.open(input_path) + try: + self.image = Image.open(input_path) + except OSError as e: + # If an error occurs opening the image, a thumbnail won't be able to + # be generated. + raise ThumbnailError from e + self.width, self.height = self.image.size self.transpose_method = None try: diff --git a/tests/rest/media/v1/test_media_storage.py b/tests/rest/media/v1/test_media_storage.py index f4f3e56777..5f897d49cf 100644 --- a/tests/rest/media/v1/test_media_storage.py +++ b/tests/rest/media/v1/test_media_storage.py @@ -120,12 +120,13 @@ class _TestImage: extension = attr.ib(type=bytes) expected_cropped = attr.ib(type=Optional[bytes]) expected_scaled = attr.ib(type=Optional[bytes]) + expected_found = attr.ib(default=True, type=bool) @parameterized_class( ("test_image",), [ - # smol png + # smoll png ( _TestImage( unhexlify( @@ -161,6 +162,8 @@ class _TestImage: None, ), ), + # an empty file + (_TestImage(b"", b"image/gif", b".gif", None, None, False,),), ], ) class MediaRepoTests(unittest.HomeserverTestCase): @@ -303,12 +306,16 @@ class MediaRepoTests(unittest.HomeserverTestCase): self.assertEqual(headers.getRawHeaders(b"Content-Disposition"), None) def test_thumbnail_crop(self): - self._test_thumbnail("crop", self.test_image.expected_cropped) + self._test_thumbnail( + "crop", self.test_image.expected_cropped, self.test_image.expected_found + ) def test_thumbnail_scale(self): - self._test_thumbnail("scale", self.test_image.expected_scaled) + self._test_thumbnail( + "scale", self.test_image.expected_scaled, self.test_image.expected_found + ) - def _test_thumbnail(self, method, expected_body): + def _test_thumbnail(self, method, expected_body, expected_found): params = "?width=32&height=32&method=" + method request, channel = self.make_request( "GET", self.media_id + params, shorthand=False @@ -325,11 +332,23 @@ class MediaRepoTests(unittest.HomeserverTestCase): ) self.pump() - self.assertEqual(channel.code, 200) - if expected_body is not None: - self.assertEqual( - channel.result["body"], expected_body, channel.result["body"] - ) + if expected_found: + self.assertEqual(channel.code, 200) + if expected_body is not None: + self.assertEqual( + channel.result["body"], expected_body, channel.result["body"] + ) + else: + # ensure that the result is at least some valid image + Image.open(BytesIO(channel.result["body"])) else: - # ensure that the result is at least some valid image - Image.open(BytesIO(channel.result["body"])) + # A 404 with a JSON body. + self.assertEqual(channel.code, 404) + self.assertEqual( + channel.json_body, + { + "errcode": "M_NOT_FOUND", + "error": "Not found [b'example.com', b'12345?width=32&height=32&method=%s']" + % method, + }, + )