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# -*- coding: utf-8 -*-
# _streaming_resource.py
# Copyright (C) 2017 LEAP
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
A twisted resource that serves download as a single stream of multiple blobs.
-> POST .../uuid/ DATA: [blob_id, blob_id2, ..., blob_idn]
<- [(size(blob_id), content(blob_id)) for blob_id in DATA] (as a binary stream)
"""
import json
import base64
from zope.interface import implementer
from twisted.internet.interfaces import IPushProducer
from twisted.internet import task
from twisted.web.server import NOT_DONE_YET
from twisted.web.resource import Resource
from leap.soledad.common.log import getLogger
from . import interfaces
from ._blobs import FilesystemBlobsBackend
from ._blobs import ImproperlyConfiguredException
__all__ = ['StreamingResource']
logger = getLogger(__name__)
class StreamingResource(Resource):
isLeaf = True
# Allowed backend classes are defined here
handlers = {"filesystem": FilesystemBlobsBackend}
def __init__(self, backend, blobs_path, **backend_kwargs):
Resource.__init__(self)
self._blobs_path = blobs_path
backend_kwargs.update({'blobs_path': blobs_path})
if backend not in self.handlers:
raise ImproperlyConfiguredException("No such backend: %s", backend)
self._handler = self.handlers[backend](**backend_kwargs)
assert interfaces.IBlobsBackend.providedBy(self._handler)
def render_POST(self, request):
user = request.postpath[0]
namespace = request.args.get('namespace', ['default'])[0]
db = self._handler
raw_content = request.content.read()
blob_ids = json.loads(raw_content)
paths = []
for blob_id in blob_ids:
path = db._get_path(user, blob_id, namespace)
size = db.get_blob_size(user, blob_id, namespace)
paths.append((blob_id, path, size))
DownstreamProducer(request, paths).start()
return NOT_DONE_YET
@implementer(IPushProducer)
class DownstreamProducer(object):
chunk_size = 2**14
def __init__(self, request, paths):
self.request = request
self.paths = paths
def start(self):
iterator = self._gen_data()
self.task = task.cooperate(iterator)
self.request.registerProducer(self, streaming=True)
def resumeProducing(self):
return self.task.resume()
def pauseProducing(self):
return self.task.pause()
def _gen_data(self):
request, paths = self.request, self.paths
while paths:
blob_id, path, size = paths.pop(0)
request.write('%08x' % size) # sends file size
with open(path, 'rb') as blob_fd:
blob_fd.seek(-16, 2)
encoded_tag = base64.urlsafe_b64encode(blob_fd.read())
request.write(encoded_tag) # sends AES-GCM tag
blob_fd.seek(0)
request.write(' ')
data = blob_fd.read(self.chunk_size)
while data:
yield
request.write(data)
data = blob_fd.read(self.chunk_size)
request.unregisterProducer()
request.finish()
def stopProducing(self):
self.request = None
return self.task.stop()
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