Major rewrite of the `media` routes.

- Streaming and media subtitles endpoints moved from Flask to Tornado
  routes - the old Flask streaming route no longer worked behind a
  Tornado server.

- Storing the streaming state on Redis rather than in a local variable,
  or different Tornado processes may end up with different copies of the
  registry.

Closes: #336

platypush/backend/http/app/routes/plugins/media/__init__.py

@@ -1,207 +0,0 @@
-import hashlib
-import json
-import threading
-
-from flask import Response
-
-from platypush.backend.http.app.utils import get_remote_base_url, logger, \
-    send_message
-
-from platypush.backend.http.media.handlers import MediaHandler
-
-media_map = {}
-media_map_lock = threading.RLock()
-
-# Size for the bytes chunk sent over the media streaming infra
-STREAMING_CHUNK_SIZE = 4096
-
-# Maximum range size to be sent through the media streamer if Range header
-# is not set
-STREAMING_BLOCK_SIZE = 3145728
-
-
-def get_media_url(media_id):
-    return '{url}/media/{media_id}'.format(
-        url=get_remote_base_url(), media_id=media_id)
-
-
-def get_media_id(source):
-    return hashlib.sha1(source.encode()).hexdigest()
-
-
-def register_media(source, subtitles=None):
-    global media_map, media_map_lock
-
-    media_id = get_media_id(source)
-    media_url = get_media_url(media_id)
-
-    with media_map_lock:
-        if media_id in media_map:
-            return media_map[media_id]
-
-    subfile = None
-    if subtitles:
-        req = {
-            'type': 'request',
-            'action': 'media.subtitles.download',
-            'args': {
-                'link': subtitles,
-                'convert_to_vtt': True,
-            }
-        }
-
-        try:
-            subfile = (send_message(req).output or {}).get('filename')
-        except Exception as e:
-            logger().warning('Unable to load subtitle {}: {}'
-                             .format(subtitles, str(e)))
-
-    with media_map_lock:
-        media_hndl = MediaHandler.build(source, url=media_url, subtitles=subfile)
-        media_map[media_id] = media_hndl
-        media_hndl.media_id = media_id
-
-    logger().info('Streaming "{}" on {}'.format(source, media_url))
-    return media_hndl
-
-
-def unregister_media(source):
-    global media_map, media_map_lock
-
-    if source is None:
-        raise KeyError('No media_id specified')
-
-    media_id = get_media_id(source)
-    media_info = {}
-
-    with media_map_lock:
-        if media_id not in media_map:
-            raise FileNotFoundError('{} is not a registered media_id'.
-                                    format(source))
-        media_info = media_map.pop(media_id)
-
-    logger().info('Unregistered {} from {}'.format(source, media_info.get('url')))
-    return media_info
-
-
-def stream_media(media_id, req):
-    global STREAMING_BLOCK_SIZE, STREAMING_CHUNK_SIZE
-
-    media_hndl = media_map.get(media_id)
-    if not media_hndl:
-        raise FileNotFoundError('{} is not a registered media_id'.format(media_id))
-
-    range_hdr = req.headers.get('range')
-    content_length = media_hndl.content_length
-    status_code = 200
-
-    headers = {
-        'Accept-Ranges': 'bytes',
-        'Content-Type': media_hndl.mime_type,
-    }
-
-    if 'download' in req.args:
-        headers['Content-Disposition'] = 'attachment' + \
-                                         ('; filename="{}"'.format(media_hndl.filename) if
-                                          media_hndl.filename else '')
-
-    if range_hdr:
-        headers['Accept-Ranges'] = 'bytes'
-        from_bytes, to_bytes = range_hdr.replace('bytes=', '').split('-')
-        from_bytes = int(from_bytes)
-
-        if not to_bytes:
-            to_bytes = content_length - 1
-            content_length -= from_bytes
-        else:
-            to_bytes = int(to_bytes)
-            content_length = to_bytes - from_bytes
-
-        status_code = 206
-        headers['Content-Range'] = 'bytes {start}-{end}/{size}'.format(
-            start=from_bytes, end=to_bytes,
-            size=media_hndl.content_length)
-    else:
-        from_bytes = 0
-        to_bytes = STREAMING_BLOCK_SIZE
-
-    headers['Content-Length'] = content_length
-
-    return Response(media_hndl.get_data(
-        from_bytes=from_bytes, to_bytes=to_bytes,
-        chunk_size=STREAMING_CHUNK_SIZE),
-        status_code, headers=headers, mimetype=headers['Content-Type'],
-        direct_passthrough=True)
-
-
-def add_subtitles(media_id, req):
-    """
-    This route can be used to download and/or expose subtitles files
-    associated to a media file
-    """
-
-    media_hndl = media_map.get(media_id)
-    if not media_hndl:
-        raise FileNotFoundError('{} is not a registered media_id'.format(media_id))
-
-    subfile = None
-    if req.data:
-        subfile = json.loads(req.data.decode('utf-8')).get('filename')
-        if not subfile:
-            raise AttributeError('No filename specified in the request')
-
-    if not subfile:
-        if not media_hndl.path:
-            raise NotImplementedError(
-                'Subtitles are currently only supported for local media files')
-
-        req = {
-            'type': 'request',
-            'action': 'media.subtitles.get_subtitles',
-            'args': {
-                'resource': media_hndl.path,
-            }
-        }
-
-        try:
-            subtitles = send_message(req).output or []
-        except Exception as e:
-            raise RuntimeError('Could not get subtitles: {}'.format(str(e)))
-
-        if not subtitles:
-            raise FileNotFoundError('No subtitles found for resource {}'.
-                                    format(media_hndl.path))
-
-        req = {
-            'type': 'request',
-            'action': 'media.subtitles.download',
-            'args': {
-                'link': subtitles[0].get('SubDownloadLink'),
-                'media_resource': media_hndl.path,
-                'convert_to_vtt': True,
-            }
-        }
-
-        subfile = (send_message(req).output or {}).get('filename')
-
-    media_hndl.set_subtitles(subfile)
-    return {
-        'filename': subfile,
-        'url': get_remote_base_url() + '/media/subtitles/' + media_id + '.vtt',
-    }
-
-
-def remove_subtitles(media_id):
-    media_hndl = media_map.get(media_id)
-    if not media_hndl:
-        raise FileNotFoundError('{} is not a registered media_id'.
-                                format(media_id))
-
-    if not media_hndl.subtitles:
-        raise FileNotFoundError('{} has no subtitles attached'.
-                                format(media_id))
-
-    media_hndl.remove_subtitles()
-    return {}
-
-# vim:sw=4:ts=4:et:

platypush/backend/http/app/routes/plugins/media/stream.py

@@ -1,87 +0,0 @@
-import json
-
-from flask import abort, jsonify, request, Blueprint
-
-from platypush.backend.http.app import template_folder
-from platypush.backend.http.app.utils import logger, get_remote_base_url
-from platypush.backend.http.app.routes.plugins.media import media_map, \
-    stream_media, register_media, unregister_media
-
-media = Blueprint('media', __name__, template_folder=template_folder)
-
-# Declare routes list
-__routes__ = [
-    media,
-]
-
-
-@media.route('/media', methods=['GET'])
-def get_media():
-    """
-    This route can be used to get the list of registered streams
-    """
-    return jsonify([dict(media) for media in media_map.values()])
-
-
-@media.route('/media', methods=['PUT'])
-def add_media():
-    """
-    This route can be used by the `media` plugin to add streaming content over HTTP
-    """
-
-    args = {}
-    try:
-        args = json.loads(request.data.decode('utf-8'))
-    except Exception as e:
-        abort(400, 'Invalid JSON request: {}'.format(str(e)))
-
-    source = args.get('source')
-    if not source:
-        abort(400, 'The request does not contain any source')
-
-    subtitles = args.get('subtitles')
-    try:
-        media_hndl = register_media(source, subtitles)
-        ret = dict(media_hndl)
-        if media_hndl.subtitles:
-            ret['subtitles_url'] = get_remote_base_url() + \
-                '/media/subtitles/' + media_hndl.media_id + '.vtt'
-        return jsonify(ret)
-    except FileNotFoundError as e:
-        abort(404, str(e))
-    except AttributeError as e:
-        abort(400, str(e))
-    except Exception as e:
-        logger().exception(e)
-        abort(500, str(e))
-
-
-@media.route('/media/<media_id>', methods=['GET', 'DELETE'])
-def stream_or_delete_media(media_id):
-    """
-    This route can be used to stream active media points or unregister
-    a mounted media stream
-    """
-
-    # Remove the extension
-    media_id = '.'.join(media_id.split('.')[:-1])
-
-    try:
-        if request.method == 'GET':
-            if media_id is None:
-                return jsonify([dict(media) for media in media_map.values()])
-            else:
-                return stream_media(media_id, request)
-        else:
-            media_info = unregister_media(media_id)
-            return jsonify(media_info)
-    except (AttributeError, FileNotFoundError) as e:
-        abort(404, str(e))
-    except KeyError as e:
-        abort(400, str(e))
-    except Exception as e:
-        logger().exception(e)
-        abort(500, str(e))
-
-
-# vim:sw=4:ts=4:et:

platypush/backend/http/app/routes/plugins/media/subtitles.py

@@ -1,51 +0,0 @@
-import os
-
-from flask import abort, jsonify, request, send_from_directory, Blueprint
-
-from platypush.backend.http.app import template_folder
-from platypush.backend.http.app.routes.plugins.media import media_map, \
-    remove_subtitles, add_subtitles
-
-subtitles = Blueprint('subtitles', __name__, template_folder=template_folder)
-
-# Declare routes list
-__routes__ = [
-    subtitles,
-]
-
-@subtitles.route('/media/subtitles/<media_id>.vtt', methods=['GET', 'POST', 'DELETE'])
-def handle_subtitles(media_id):
-    """
-    This route can be used to download and/or expose subtitle files
-    associated to a media file
-    """
-
-    if request.method == 'GET':
-        media_hndl = media_map.get(media_id)
-        if not media_hndl:
-            abort(404, 'No such media')
-
-        if not media_hndl.subtitles:
-            abort(404, 'The media has no subtitles attached')
-
-        return send_from_directory(
-            os.path.dirname(media_hndl.subtitles),
-            os.path.basename(media_hndl.subtitles),
-            mimetype='text/vtt')
-
-    try:
-        if request.method == 'DELETE':
-            return jsonify(remove_subtitles(media_id))
-        else:
-            return jsonify(add_subtitles(media_id, request))
-    except FileNotFoundError as e:
-        abort(404, str(e))
-    except AttributeError as e:
-        abort(400, str(e))
-    except NotImplementedError as e:
-        abort(422, str(e))
-    except Exception as e:
-        abort(500, str(e))
-
-
-# vim:sw=4:ts=4:et:

platypush/backend/http/app/streaming/plugins/media/__init__.py

@@ -0,0 +1,5 @@
+from ._stream import MediaStreamRoute
+from ._subtitles import MediaSubtitlesRoute
+
+
+__all__ = ["MediaStreamRoute", "MediaSubtitlesRoute"]

platypush/backend/http/app/streaming/plugins/media/_constants.py

@@ -0,0 +1,17 @@
+from typing import Dict
+
+from platypush.backend.http.media.handlers import MediaHandler
+
+
+# Size for the bytes chunk sent over the media streaming infra
+STREAMING_CHUNK_SIZE = 4096
+
+# Maximum range size to be sent through the media streamer if Range header
+# is not set
+STREAMING_BLOCK_SIZE = 3145728
+
+# Name of the Redis variable used to store the media map across several
+# Web processes
+MEDIA_MAP_VAR = 'platypush__stream_media_map'
+
+MediaMap = Dict[str, MediaHandler]

platypush/backend/http/app/streaming/plugins/media/_register.py

@@ -0,0 +1,44 @@
+from typing import Optional
+
+from platypush.backend.http.app.utils import logger, send_request
+from platypush.backend.http.media.handlers import MediaHandler
+
+from ._registry import load_media_map, save_media_map
+
+
+def get_media_url(media_id: str) -> str:
+    """
+    :returns: The URL of a media file given its ID
+    """
+    return f'/media/{media_id}'
+
+
+def register_media(source: str, subtitles: Optional[str] = None) -> MediaHandler:
+    """
+    Registers a media file and returns its associated media handler.
+    """
+    media_id = MediaHandler.get_media_id(source)
+    media_url = get_media_url(media_id)
+    media_map = load_media_map()
+    subfile = None
+
+    if subtitles:
+        req = {
+            'type': 'request',
+            'action': 'media.subtitles.download',
+            'args': {
+                'link': subtitles,
+                'convert_to_vtt': True,
+            },
+        }
+
+        try:
+            subfile = (send_request(req) or {}).get('filename')
+        except Exception as e:
+            logger().warning('Unable to load subtitle %s: %s', subtitles, e)
+
+    media_hndl = MediaHandler.build(source, url=media_url, subtitles=subfile)
+    media_map[media_id] = media_hndl
+    save_media_map(media_map)
+    logger().info('Streaming "%s" on %s', source, media_url)
+    return media_hndl

platypush/backend/http/app/streaming/plugins/media/_registry.py

@@ -0,0 +1,40 @@
+import json
+import multiprocessing
+
+from platypush.backend.http.app.utils import logger
+from platypush.backend.http.media.handlers import MediaHandler
+from platypush.message import Message
+from platypush.utils import get_redis
+
+from ._constants import MEDIA_MAP_VAR, MediaMap
+
+media_map_lock = multiprocessing.RLock()
+
+
+def load_media_map() -> MediaMap:
+    """
+    Load the media map from the server.
+    """
+    with media_map_lock:
+        redis = get_redis()
+        try:
+            media_map = json.loads(
+                ((redis.mget(MEDIA_MAP_VAR) or [None])[0] or b'{}').decode()  # type: ignore
+            )
+        except Exception as e:
+            logger().warning('Could not load media map: %s', e)
+            return {}
+
+    return {
+        media_id: MediaHandler.build(**media_info)
+        for media_id, media_info in media_map.items()
+    }
+
+
+def save_media_map(new_map: MediaMap):
+    """
+    Updates the stored media map on the server.
+    """
+    with media_map_lock:
+        redis = get_redis()
+        redis.mset({MEDIA_MAP_VAR: json.dumps(new_map, cls=Message.Encoder)})

platypush/backend/http/app/streaming/plugins/media/_stream.py

@@ -0,0 +1,149 @@
+import json
+from typing import Optional
+
+from tornado.web import stream_request_body
+
+from platypush.backend.http.app.streaming import StreamingRoute
+
+from ._constants import STREAMING_BLOCK_SIZE, STREAMING_CHUNK_SIZE
+from ._register import register_media
+from ._registry import load_media_map
+from ._unregister import unregister_media
+
+
+@stream_request_body
+class MediaStreamRoute(StreamingRoute):
+    """
+    Route for media streams.
+    """
+
+    SUPPORTED_METHODS = ['GET', 'PUT', 'DELETE']
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self._body = b''
+
+    @classmethod
+    def path(cls) -> str:
+        return r"^/media/?([a-zA-Z0-9_.]+)?$"
+
+    @property
+    def auth_required(self) -> bool:
+        return False
+
+    def get(self, media_id: Optional[str] = None):
+        """
+        Streams a media resource by ID.
+        """
+
+        # Return the list of registered streaming media resources if no ID is
+        # specified
+        if not media_id:
+            self.get_media()
+            return
+
+        # Strip the extension
+        media_id = '.'.join(media_id.split('.')[:-1])
+
+        try:
+            self.stream_media(media_id)
+        except Exception as e:
+            self._on_error(e)
+
+    def put(self, *_, **__):
+        """
+        The `PUT` route is used to prepare a new media resource for streaming.
+        """
+        try:
+            self.add_media()
+        except Exception as e:
+            self._on_error(e)
+
+    def delete(self, media_id: Optional[str] = None):
+        """
+        Removes the given media_id from the map of streaming media.
+        """
+        media_info = unregister_media(media_id)
+        self.write(json.dumps(media_info))
+
+    def data_received(self, chunk: bytes):
+        self._body += chunk
+
+    def add_media(self):
+        """
+        Adds a new media resource to the map of streaming media.
+        """
+        args = {}
+        try:
+            args = json.loads(self._body)
+        except Exception as e:
+            raise AssertionError(f'Invalid JSON request: {e}') from e
+
+        source = args.get('source')
+        assert source, 'The request does not contain any source'
+        subtitles = args.get('subtitles')
+        media_hndl = register_media(source, subtitles)
+        ret = media_hndl.to_json()
+        if media_hndl.subtitles:
+            ret['subtitles_url'] = f'/media/subtitles/{media_hndl.media_id}.vtt'
+
+        self.write(json.dumps(ret))
+
+    def get_media(self):
+        """
+        Returns the list of registered media resources.
+        """
+        self.add_header('Content-Type', 'application/json')
+        self.finish(json.dumps([dict(media) for media in load_media_map().values()]))
+
+    def stream_media(self, media_id: str):
+        """
+        Route to stream a media file given its ID.
+        """
+        media_hndl = load_media_map().get(media_id)
+        if not media_hndl:
+            raise FileNotFoundError(f'{media_id} is not a registered media_id')
+
+        range_hdr = self.request.headers.get('Range')
+        content_length = media_hndl.content_length
+
+        self.add_header('Accept-Ranges', 'bytes')
+        self.add_header('Content-Type', media_hndl.mime_type)
+
+        if 'download' in self.request.arguments:
+            self.add_header(
+                'Content-Disposition',
+                'attachment'
+                + ('; filename="{media_hndl.filename}"' if media_hndl.filename else ''),
+            )
+
+        if range_hdr:
+            from_bytes, to_bytes = range_hdr.replace('bytes=', '').split('-')
+            from_bytes = int(from_bytes)
+
+            if not to_bytes:
+                to_bytes = content_length - 1
+                content_length -= from_bytes
+            else:
+                to_bytes = int(to_bytes)
+                content_length = to_bytes - from_bytes
+
+            self.set_status(206)
+            self.add_header(
+                'Content-Range',
+                f'bytes {from_bytes}-{to_bytes}/{media_hndl.content_length}',
+            )
+        else:
+            from_bytes = 0
+            to_bytes = STREAMING_BLOCK_SIZE
+
+        self.add_header('Content-Length', str(content_length))
+        for chunk in media_hndl.get_data(
+            from_bytes=from_bytes,
+            to_bytes=to_bytes,
+            chunk_size=STREAMING_CHUNK_SIZE,
+        ):
+            self.write(chunk)
+            self.flush()
+
+        self.finish()

platypush/backend/http/app/streaming/plugins/media/_subtitles.py

@@ -0,0 +1,140 @@
+import json
+
+from tornado.web import stream_request_body
+
+from platypush.backend.http.app.streaming import StreamingRoute
+from platypush.backend.http.app.utils.bus import send_request
+
+from ._registry import load_media_map
+
+
+@stream_request_body
+class MediaSubtitlesRoute(StreamingRoute):
+    """
+    Route for media stream subtitles.
+    """
+
+    SUPPORTED_METHODS = ['GET', 'POST', 'DELETE']
+
+    @classmethod
+    def path(cls) -> str:
+        return r"^/media/subtitles/([a-zA-Z0-9_.]+)\.vtt$"
+
+    @property
+    def auth_required(self) -> bool:
+        return False
+
+    def get(self, media_id: str):
+        """
+        GET route to retrieve the subtitles for the given media_id.
+        """
+        try:
+            self.get_subtitles(media_id)
+        except Exception as e:
+            self._on_error(e)
+
+    def post(self, media_id: str):
+        """
+        POST route to add subtitles to the given media_id.
+        """
+        try:
+            self.add_subtitles(media_id)
+        except Exception as e:
+            self._on_error(e)
+
+    def delete(self, media_id: str):
+        """
+        DELETE route to remove the subtitles for the given media_id.
+        """
+        try:
+            self.remove_subtitles(media_id)
+        except Exception as e:
+            self._on_error(e)
+
+    def get_subtitles(self, media_id: str):
+        """
+        Retrieves the subtitles for the given media_id.
+        """
+
+        media_hndl = load_media_map().get(media_id)
+        if not media_hndl:
+            raise FileNotFoundError(f'{media_id} is not a registered media_id')
+
+        if not media_hndl.subtitles:
+            raise FileNotFoundError(f'{media_id} has no subtitles')
+
+        with open(media_hndl.subtitles) as f:
+            self.set_header('Content-Type', 'text/vtt')
+            self.finish(f.read())
+
+    @staticmethod
+    def remove_subtitles(media_id: str):
+        """
+        Remove the current subtitle track from a streamed from a media file.
+        """
+        media_hndl = load_media_map().get(media_id)
+        if not media_hndl:
+            raise FileNotFoundError(f'{media_id} is not a registered media_id')
+
+        if not media_hndl.subtitles:
+            raise FileNotFoundError(f'{media_id} has no subtitles attached')
+
+        media_hndl.remove_subtitles()
+        return {}
+
+    def add_subtitles(self, media_id: str):
+        """
+        This route can be used to download and/or expose subtitles files
+        associated to a media file
+        """
+
+        media_hndl = load_media_map().get(media_id)
+        if not media_hndl:
+            raise FileNotFoundError(f'{media_id} is not a registered media_id')
+
+        subfile = None
+        if self.request.body:
+            subfile = json.loads(self.request.body).get('filename')
+            assert subfile, 'No filename specified in the request'
+
+        if not subfile:
+            if not media_hndl.path:
+                raise NotImplementedError(
+                    'Subtitles are currently only supported for local media files'
+                )
+
+            req = {
+                'type': 'request',
+                'action': 'media.subtitles.get_subtitles',
+                'args': {
+                    'resource': media_hndl.path,
+                },
+            }
+
+            try:
+                subtitles = send_request(req) or []
+            except Exception as e:
+                raise RuntimeError(f'Could not get subtitles: {e}') from e
+
+            if not subtitles:
+                raise FileNotFoundError(
+                    f'No subtitles found for resource {media_hndl.path}'
+                )
+
+            req = {
+                'type': 'request',
+                'action': 'media.subtitles.download',
+                'args': {
+                    'link': subtitles[0].get('SubDownloadLink'),
+                    'media_resource': media_hndl.path,
+                    'convert_to_vtt': True,
+                },
+            }
+
+            subfile = (send_request(req) or {}).get('filename')
+
+        media_hndl.set_subtitles(subfile)
+        return {
+            'filename': subfile,
+            'url': f'/media/subtitles/{media_id}.vtt',
+        }

platypush/backend/http/app/streaming/plugins/media/_unregister.py

@@ -0,0 +1,26 @@
+from typing import Optional
+
+from platypush.backend.http.app.utils import logger
+from platypush.backend.http.media.handlers import MediaHandler
+
+from ._registry import load_media_map, save_media_map, media_map_lock
+
+
+def unregister_media(source: Optional[str] = None):
+    """
+    Unregisters a media streaming URL file given its source.
+    """
+    assert source is not None, 'No media_id specified'
+    media_id = MediaHandler.get_media_id(source)
+    media_info = {}
+
+    with media_map_lock:
+        media_map = load_media_map()
+        if media_id not in media_map:
+            raise FileNotFoundError(f'{source} is not a registered media_id')
+
+        media_info = media_map.pop(media_id)
+        save_media_map(media_map)
+
+    logger().info('Unregistered %s from %s', source, media_info.url)
+    return media_info

platypush/backend/http/media/handlers/__init__.py

@@ -1,7 +1,7 @@
 from abc import ABC, abstractmethod
 import hashlib
 import logging
-from typing import Optional
+from typing import Generator, Optional
 
 from platypush.message import JSONAble
 
@@ -66,7 +66,7 @@ class MediaHandler(JSONAble, ABC):
         from_bytes: Optional[int] = None,
         to_bytes: Optional[int] = None,
         chunk_size: Optional[int] = None,
-    ) -> bytes:
+    ) -> Generator[bytes, None, None]:
         raise NotImplementedError()
 
     @property

platypush/backend/http/media/handlers/file.py

@@ -23,20 +23,17 @@ class FileHandler(MediaHandler):
         self.filename = self.path.split('/')[-1]
 
         if not os.path.isfile(self.path):
-            raise FileNotFoundError(f'{self.path} is not a valid file')
+            raise FileNotFoundError(self.path)
 
         self.mime_type = get_mime_type(source)
         assert self.mime_type, f'Could not detect mime type for {source}'
-        if (
-            self.mime_type[:5] not in ['video', 'audio', 'image']
-            and self.mime_type != 'application/octet-stream'
-        ):
-            raise AttributeError(
-                f'{source} is not a valid media file (detected format: {self.mime_type})'
-            )
+        assert (
+            self.mime_type[:5] in ['video', 'audio', 'image']
+            or self.mime_type == 'application/octet-stream'
+        ), f'{source} is not a valid media file (detected format: {self.mime_type})'
 
         self.extension = mimetypes.guess_extension(self.mime_type)
-        if self.url:
+        if self.url and self.extension:
             self.url += self.extension
         self.content_length = os.path.getsize(self.path)