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# -*- coding: utf-8 -*-
# _blobs.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/>.
"""
Blobs Server implementation.
This is a very simplistic implementation for the time being.
Clients should be able to opt-in util the feature is complete.
A more performant BlobsBackend can (and should) be implemented for production
environments.
"""
import os
import base64
import json
import re
from twisted.logger import Logger
from twisted.web import static
from twisted.web import resource
from twisted.web.client import FileBodyProducer
from twisted.web.server import NOT_DONE_YET
from twisted.internet import utils, defer
from zope.interface import Interface, implementer
__all__ = ['BlobsResource']
logger = Logger()
# Used for sanitizers, we accept only letters, numbers, '-' and '_'
VALID_STRINGS = re.compile('^[a-zA-Z0-9_-]+$')
# TODO some error handling needed
# [ ] sanitize path
# for the future:
# [ ] isolate user avatar in a safer way
# [ ] catch timeout in the server (and delete incomplete upload)
# [ ] chunking (should we do it on the client or on the server?)
class IBlobsBackend(Interface):
"""
An interface for a BlobsBackend.
"""
def read_blob(user, blob_id, request):
"""
Read blob with a given blob_id, and write it to the passed request.
:returns: a deferred that fires upon finishing.
"""
def list_blobs(user, request):
"""
Returns a json-encoded list of ids from user's blob.
:returns: a deferred that fires upon finishing.
"""
def tag_header(user, blob_id, request):
"""
Adds a header 'Tag' with the last 16 bytes of the encoded file,
which contains the tag.
:returns: a deferred that fires upon finishing.
"""
def write_blob(user, blob_id, request):
"""
Write blob to the storage, reading it from the passed request.
:returns: a deferred that fires upon finishing.
"""
# other stuff for the API
def delete_blob(user, blob_id):
pass
def get_blob_size(user, blob_id):
pass
def get_total_storage(user):
pass
@implementer(IBlobsBackend)
class FilesystemBlobsBackend(object):
def __init__(self, blobs_path='/tmp/blobs/', quota=200 * 1024):
self.quota = quota
if not os.path.isdir(blobs_path):
os.makedirs(blobs_path)
self.path = blobs_path
def list_blobs(self, user, request):
blob_ids = []
base_path = self._get_path(user)
for _, _, filenames in os.walk(base_path):
blob_ids += filenames
return json.dumps(blob_ids)
def tag_header(self, user, blob_id, request):
with open(self._get_path(user, blob_id)) as doc_file:
doc_file.seek(-16, 2)
tag = base64.urlsafe_b64encode(doc_file.read())
request.responseHeaders.setRawHeaders('Tag', [tag])
def read_blob(self, user, blob_id, request):
logger.info('reading blob: %s - %s' % (user, blob_id))
path = self._get_path(user, blob_id)
logger.debug('blob path: %s' % path)
_file = static.File(path, defaultType='application/octet-stream')
return _file.render_GET(request)
@defer.inlineCallbacks
def write_blob(self, user, blob_id, request):
path = self._get_path(user, blob_id)
try:
os.makedirs(os.path.split(path)[0])
except:
pass
if os.path.isfile(path):
# 409 - Conflict
request.setResponseCode(409)
request.write("Blob already exists: %s" % blob_id)
defer.returnValue(None)
used = yield self.get_total_storage(user)
if used > self.quota:
logger.error("Error 507: Quota exceeded for user: %s" % user)
request.setResponseCode(507)
request.write('Quota Exceeded!')
defer.returnValue(None)
logger.info('writing blob: %s - %s' % (user, blob_id))
fbp = FileBodyProducer(request.content)
yield fbp.startProducing(open(path, 'wb'))
def get_total_storage(self, user):
return self._get_disk_usage(self._get_path(user))
def delete_blob(user, blob_id):
raise NotImplementedError
def get_blob_size(user, blob_id):
raise NotImplementedError
@defer.inlineCallbacks
def _get_disk_usage(self, start_path):
if not os.path.isdir(start_path):
defer.returnValue(0)
cmd = ['/usr/bin/du', '-s', '-c', start_path]
output = yield utils.getProcessOutput(cmd[0], cmd[1:])
size = output.split()[0]
defer.returnValue(int(size))
def _validate_path(self, desired_path, user, blob_id):
if not VALID_STRINGS.match(user):
raise Exception("Invalid characters on user: %s" % user)
if blob_id and not VALID_STRINGS.match(blob_id):
raise Exception("Invalid characters on blob_id: %s" % blob_id)
desired_path = os.path.realpath(desired_path) # expand path references
root = os.path.realpath(self.path)
if not desired_path.startswith(root + os.sep + user):
err = "User %s tried accessing a invalid path: %s" % (user,
desired_path)
raise Exception(err)
return desired_path
def _get_path(self, user, blob_id=False):
parts = [user]
if blob_id:
parts += [blob_id[0], blob_id[0:3], blob_id[0:6]]
parts += [blob_id]
path = os.path.join(self.path, *parts)
return self._validate_path(path, user, blob_id)
class BlobsResource(resource.Resource):
isLeaf = True
# Allowed factory classes are defined here
blobsFactoryClass = FilesystemBlobsBackend
def __init__(self, blobs_path):
# TODO pass the backend as configurable option #8804
resource.Resource.__init__(self)
self._blobs_path = blobs_path
self._handler = self.blobsFactoryClass(blobs_path)
assert IBlobsBackend.providedBy(self._handler)
# TODO double check credentials, we can have then
# under request.
def render_GET(self, request):
logger.info("http get: %s" % request.path)
user, blob_id = self._validate(request)
if not blob_id:
return self._handler.list_blobs(user, request)
self._handler.tag_header(user, blob_id, request)
return self._handler.read_blob(user, blob_id, request)
def render_PUT(self, request):
logger.info("http put: %s" % request.path)
user, blob_id = self._validate(request)
d = self._handler.write_blob(user, blob_id, request)
d.addCallback(lambda _: request.finish())
d.addErrback(self._error, request)
return NOT_DONE_YET
def _error(self, e, request):
logger.error('Error processing request: %s' % e.getErrorMessage())
request.setResponseCode(500)
request.finish()
def _validate(self, request):
for arg in request.postpath:
if arg and not VALID_STRINGS.match(arg):
raise Exception('Invalid blob resource argument: %s' % arg)
return request.postpath
if __name__ == '__main__':
# A dummy blob server
# curl -X PUT --data-binary @/tmp/book.pdf localhost:9000/user/someid
# curl -X GET -o /dev/null localhost:9000/user/somerandomstring
from twisted.python import log
import sys
log.startLogging(sys.stdout)
from twisted.web.server import Site
from twisted.internet import reactor
# parse command line arguments
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--port', default=9000, type=int)
parser.add_argument('--path', default='/tmp/blobs/user')
args = parser.parse_args()
root = BlobsResource(args.path)
# I picture somethink like
# BlobsResource(backend="filesystem", backend_opts={'path': '/tmp/blobs'})
factory = Site(root)
reactor.listenTCP(args.port, factory)
reactor.run()
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