swift/swift/common/middleware/listing_formats.py

212 lines
7.7 KiB
Python

# Copyright (c) 2017 OpenStack Foundation
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import json
import six
from xml.etree.cElementTree import Element, SubElement, tostring
from swift.common.constraints import valid_api_version
from swift.common.http import HTTP_NO_CONTENT
from swift.common.request_helpers import get_param
from swift.common.swob import HTTPException, HTTPNotAcceptable, Request, \
RESPONSE_REASONS
#: Mapping of query string ``format=`` values to their corresponding
#: content-type values.
FORMAT2CONTENT_TYPE = {'plain': 'text/plain', 'json': 'application/json',
'xml': 'application/xml'}
#: Maximum size of a valid JSON container listing body. If we receive
#: a container listing response larger than this, assume it's a staticweb
#: response and pass it on to the client.
# Default max object length is 1024, default container listing limit is 1e4;
# add a fudge factor for things like hash, last_modified, etc.
MAX_CONTAINER_LISTING_CONTENT_LENGTH = 1024 * 10000 * 2
def get_listing_content_type(req):
"""
Determine the content type to use for an account or container listing
response.
:param req: request object
:returns: content type as a string (e.g. text/plain, application/json)
:raises HTTPNotAcceptable: if the requested content type is not acceptable
:raises HTTPBadRequest: if the 'format' query param is provided and
not valid UTF-8
"""
query_format = get_param(req, 'format')
if query_format:
req.accept = FORMAT2CONTENT_TYPE.get(
query_format.lower(), FORMAT2CONTENT_TYPE['plain'])
out_content_type = req.accept.best_match(
['text/plain', 'application/json', 'application/xml', 'text/xml'])
if not out_content_type:
raise HTTPNotAcceptable(request=req)
return out_content_type
def account_to_xml(listing, account_name):
doc = Element('account', name=account_name.decode('utf-8'))
doc.text = '\n'
for record in listing:
if 'subdir' in record:
name = record.pop('subdir')
sub = SubElement(doc, 'subdir', name=name)
else:
sub = SubElement(doc, 'container')
for field in ('name', 'count', 'bytes', 'last_modified'):
SubElement(sub, field).text = six.text_type(
record.pop(field))
sub.tail = '\n'
return tostring(doc, encoding='UTF-8').replace(
"<?xml version='1.0' encoding='UTF-8'?>",
'<?xml version="1.0" encoding="UTF-8"?>', 1)
def container_to_xml(listing, base_name):
doc = Element('container', name=base_name.decode('utf-8'))
for record in listing:
if 'subdir' in record:
name = record.pop('subdir')
sub = SubElement(doc, 'subdir', name=name)
SubElement(sub, 'name').text = name
else:
sub = SubElement(doc, 'object')
for field in ('name', 'hash', 'bytes', 'content_type',
'last_modified'):
SubElement(sub, field).text = six.text_type(
record.pop(field))
return tostring(doc, encoding='UTF-8').replace(
"<?xml version='1.0' encoding='UTF-8'?>",
'<?xml version="1.0" encoding="UTF-8"?>', 1)
def listing_to_text(listing):
def get_lines():
for item in listing:
if 'name' in item:
yield item['name'].encode('utf-8') + b'\n'
else:
yield item['subdir'].encode('utf-8') + b'\n'
return b''.join(get_lines())
class ListingFilter(object):
def __init__(self, app):
self.app = app
def __call__(self, env, start_response):
req = Request(env)
try:
# account and container only
version, acct, cont = req.split_path(2, 3)
except ValueError:
return self.app(env, start_response)
if not valid_api_version(version) or req.method not in ('GET', 'HEAD'):
return self.app(env, start_response)
# OK, definitely have an account/container request.
# Get the desired content-type, then force it to a JSON request.
try:
out_content_type = get_listing_content_type(req)
except HTTPException as err:
return err(env, start_response)
params = req.params
params['format'] = 'json'
req.params = params
status, headers, resp_iter = req.call_application(self.app)
header_to_index = {}
resp_content_type = resp_length = None
for i, (header, value) in enumerate(headers):
header = header.lower()
if header == 'content-type':
header_to_index[header] = i
resp_content_type = value.partition(';')[0]
elif header == 'content-length':
header_to_index[header] = i
resp_length = int(value)
if not status.startswith('200 '):
start_response(status, headers)
return resp_iter
if resp_content_type != 'application/json':
start_response(status, headers)
return resp_iter
if resp_length is None or \
resp_length > MAX_CONTAINER_LISTING_CONTENT_LENGTH:
start_response(status, headers)
return resp_iter
def set_header(header, value):
if value is None:
del headers[header_to_index[header]]
else:
headers[header_to_index[header]] = (
headers[header_to_index[header]][0], str(value))
if req.method == 'HEAD':
set_header('content-type', out_content_type + '; charset=utf-8')
set_header('content-length', None) # don't know, can't determine
start_response(status, headers)
return resp_iter
body = b''.join(resp_iter)
try:
listing = json.loads(body)
# Do a couple sanity checks
if not isinstance(listing, list):
raise ValueError
if not all(isinstance(item, dict) for item in listing):
raise ValueError
except ValueError:
# Static web listing that's returning invalid JSON?
# Just pass it straight through; that's about all we *can* do.
start_response(status, headers)
return [body]
try:
if out_content_type.endswith('/xml'):
if cont:
body = container_to_xml(listing, cont)
else:
body = account_to_xml(listing, acct)
elif out_content_type == 'text/plain':
body = listing_to_text(listing)
# else, json -- we continue down here to be sure we set charset
except KeyError:
# listing was in a bad format -- funky static web listing??
start_response(status, headers)
return [body]
if not body:
status = '%s %s' % (HTTP_NO_CONTENT,
RESPONSE_REASONS[HTTP_NO_CONTENT][0])
set_header('content-type', out_content_type + '; charset=utf-8')
set_header('content-length', len(body))
start_response(status, headers)
return [body]
def filter_factory(global_conf, **local_conf):
return ListingFilter