Merge branch 'Unrud-rights'

This commit is contained in:
Guillaume Ayoub 2016-08-04 23:35:08 +02:00
commit 263f31c84b
5 changed files with 292 additions and 314 deletions

View File

@ -29,6 +29,7 @@ should have been included in this package.
import base64
import contextlib
import os
import posixpath
import pprint
import shlex
import socket
@ -38,6 +39,7 @@ import subprocess
import threading
import wsgiref.simple_server
import zlib
from contextlib import contextmanager
from http import client
from urllib.parse import unquote, urlparse
@ -184,60 +186,31 @@ class Application:
def collect_allowed_items(self, items, user):
"""Get items from request that user is allowed to access."""
read_last_collection_allowed = None
write_last_collection_allowed = None
read_allowed_items = []
write_allowed_items = []
for item in items:
if isinstance(item, self.Collection):
if self.authorized(user, item, "r"):
self.logger.debug(
"%s has read access to collection %s" %
(user or "Anonymous", item.path or "/"))
read_last_collection_allowed = True
read_allowed_items.append(item)
else:
self.logger.debug(
"%s has NO read access to collection %s" %
(user or "Anonymous", item.path or "/"))
read_last_collection_allowed = False
if self.authorized(user, item, "w"):
self.logger.debug(
"%s has write access to collection %s" %
(user or "Anonymous", item.path or "/"))
write_last_collection_allowed = True
write_allowed_items.append(item)
else:
self.logger.debug(
"%s has NO write access to collection %s" %
(user or "Anonymous", item.path or "/"))
write_last_collection_allowed = False
path = item.path
else:
# item is not a collection, it's the child of the last
# collection we've met in the loop. Only add this item
# if this last collection was allowed.
if read_last_collection_allowed:
self.logger.debug(
"%s has read access to item %s" %
(user or "Anonymous", item.href))
read_allowed_items.append(item)
else:
self.logger.debug(
"%s has NO read access to item %s" %
(user or "Anonymous", item.href))
if write_last_collection_allowed:
self.logger.debug(
"%s has write access to item %s" %
(user or "Anonymous", item.href))
write_allowed_items.append(item)
else:
self.logger.debug(
"%s has NO write access to item %s" %
(user or "Anonymous", item.href))
path = item.collection.path
if self.authorized(user, path, "r"):
self.logger.debug(
"%s has read access to collection %s" %
(user or "Anonymous", path or "/"))
read_allowed_items.append(item)
else:
self.logger.debug(
"%s has NO read access to collection %s" %
(user or "Anonymous", path or "/"))
if self.authorized(user, path, "w"):
self.logger.debug(
"%s has write access to collection %s" %
(user or "Anonymous", path or "/"))
write_allowed_items.append(item)
else:
self.logger.debug(
"%s has NO write access to collection %s" %
(user or "Anonymous", path or "/"))
return read_allowed_items, write_allowed_items
def __call__(self, environ, start_response):
@ -305,12 +278,11 @@ class Application:
# Create principal collection
if user and is_authenticated:
principal_path = "/%s/" % user
collection = self.Collection(principal_path, True)
if self.authorized(user, collection, "w"):
if self.authorized(user, principal_path, "w"):
with self.Collection.acquire_lock("r"):
principal = next(
self.Collection.discover(principal_path), None)
if not principal or principal.path != user:
if not principal:
with self.Collection.acquire_lock("w"):
self.Collection.create_collection(principal_path)
@ -333,34 +305,7 @@ class Application:
content = None
if is_valid_user:
if function in (
self.do_GET, self.do_HEAD, self.do_OPTIONS,
self.do_PROPFIND, self.do_REPORT):
lock_mode = "r"
else:
lock_mode = "w"
with self.Collection.acquire_lock(lock_mode):
items = self.Collection.discover(
path, environ.get("HTTP_DEPTH", "0"))
read_allowed_items, write_allowed_items = (
self.collect_allowed_items(items, user))
if (read_allowed_items or write_allowed_items or
is_authenticated and function == self.do_PROPFIND or
function == self.do_OPTIONS):
status, headers, answer = function(
environ, read_allowed_items, write_allowed_items,
content, user)
hook = self.configuration.get("storage", "hook")
if lock_mode == "w" and hook:
self.logger.debug("Running hook")
folder = os.path.expanduser(
self.configuration.get(
"storage", "filesystem_folder"))
subprocess.check_call(
hook % {"user": shlex.quote(user or "Anonymous")},
shell=True, cwd=folder)
else:
status, headers, answer = NOT_ALLOWED
status, headers, answer = function(environ, path, content, user)
else:
status, headers, answer = NOT_ALLOWED
@ -397,142 +342,154 @@ class Application:
return response(status, headers, answer)
def do_DELETE(self, environ, read_collections, write_collections, content,
user):
def _access(self, user, path, permission, item=None):
"""Checks if ``user`` can access ``path`` or the parent collection
with ``permission``.
``permission`` must either be "r" or "w".
If ``item`` is given, only access to that class of item is checked.
"""
path = storage.sanitize_path(path)
parent_path = storage.sanitize_path(
"/%s/" % posixpath.dirname(path.strip("/")))
allowed = False
if not item or isinstance(item, self.Collection):
allowed |= self.authorized(user, path, permission)
if not item or not isinstance(item, self.Collection):
allowed |= self.authorized(user, parent_path, permission)
return allowed
@contextmanager
def _lock_collection(self, lock_mode, user):
"""Lock the collection with ``permission`` and execute hook."""
with self.Collection.acquire_lock(lock_mode) as value:
yield value
hook = self.configuration.get("storage", "hook")
if lock_mode == "w" and hook:
self.logger.debug("Running hook")
folder = os.path.expanduser(self.configuration.get(
"storage", "filesystem_folder"))
subprocess.check_call(
hook % {"user": shlex.quote(user or "Anonymous")},
shell=True, cwd=folder)
def do_DELETE(self, environ, path, content, user):
"""Manage DELETE request."""
if not write_collections:
if not self._access(user, path, "w"):
return NOT_ALLOWED
collection = write_collections[0]
if collection.path == environ["PATH_INFO"].strip("/"):
# Path matching the collection, the collection must be deleted
item = collection
else:
# Try to get an item matching the path
name = xmlutils.name_from_path(environ["PATH_INFO"], collection)
item = collection.get(name)
if item:
with self._lock_collection("w", user):
item = next(self.Collection.discover(path, depth="0"), None)
if not self._access(user, path, "w", item):
return NOT_ALLOWED
if not item:
return client.GONE, {}, None
if_match = environ.get("HTTP_IF_MATCH", "*")
if if_match in ("*", item.etag):
# No ETag precondition or precondition verified, delete item
answer = xmlutils.delete(environ["PATH_INFO"], collection)
return client.OK, {}, answer
if if_match not in ("*", item.etag):
# ETag precondition not verified, do not delete item
return client.PRECONDITION_FAILED, {}, None
if isinstance(item, self.Collection):
answer = xmlutils.delete(path, item)
else:
answer = xmlutils.delete(path, item.collection, item.href)
return client.OK, {}, answer
# No item or ETag precondition not verified, do not delete item
return client.PRECONDITION_FAILED, {}, None
def do_GET(self, environ, read_collections, write_collections, content,
user):
def do_GET(self, environ, path, content, user):
"""Manage GET request."""
# Display a "Radicale works!" message if the root URL is requested
if environ["PATH_INFO"] == "/":
if not path.strip("/"):
headers = {"Content-type": "text/html"}
answer = "<!DOCTYPE html>\n<title>Radicale</title>Radicale works!"
return client.OK, headers, answer
if not read_collections:
if not self._access(user, path, "r"):
return NOT_ALLOWED
collection = read_collections[0]
item_name = xmlutils.name_from_path(environ["PATH_INFO"], collection)
if item_name:
# Get collection item
item = collection.get(item_name)
if item:
answer = item.serialize()
etag = item.etag
else:
return client.NOT_FOUND, {}, None
else:
# Get whole collection
answer = collection.serialize()
if answer is None:
with self._lock_collection("r", user):
item = next(self.Collection.discover(path, depth="0"), None)
if not self._access(user, path, "r", item):
return NOT_ALLOWED
if not item:
return client.NOT_FOUND, {}, None
if isinstance(item, self.Collection):
collection = item
else:
etag = collection.etag
if answer:
collection = item.collection
content_type = storage.MIMETYPES.get(collection.get_meta("tag"),
"text/plain")
headers = {
"Content-Type": storage.MIMETYPES[collection.get_meta("tag")],
"Content-Type": content_type,
"Last-Modified": collection.last_modified,
"ETag": etag}
else:
headers = {}
return client.OK, headers, answer
"ETag": item.etag}
answer = item.serialize()
return client.OK, headers, answer
def do_HEAD(self, environ, read_collections, write_collections, content,
user):
def do_HEAD(self, environ, path, content, user):
"""Manage HEAD request."""
status, headers, answer = self.do_GET(
environ, read_collections, write_collections, content, user)
status, headers, answer = self.do_GET(environ, path, content, user)
return status, headers, None
def do_MKCALENDAR(self, environ, read_collections, write_collections,
content, user):
def do_MKCALENDAR(self, environ, path, content, user):
"""Manage MKCALENDAR request."""
if not write_collections:
if not self.authorized(user, path, "w"):
return NOT_ALLOWED
collection = write_collections[0]
with self._lock_collection("w", user):
item = next(self.Collection.discover(path, depth="0"), None)
if item:
return client.CONFLICT, {}, None
props = xmlutils.props_from_request(content)
props["tag"] = "VCALENDAR"
# TODO: use this?
# timezone = props.get("C:calendar-timezone")
self.Collection.create_collection(path, props=props)
return client.CREATED, {}, None
props = xmlutils.props_from_request(content)
props["tag"] = "VCALENDAR"
# TODO: use this?
# timezone = props.get("C:calendar-timezone")
collection = self.Collection.create_collection(
environ["PATH_INFO"], props=props)
return client.CREATED, {}, None
def do_MKCOL(self, environ, read_collections, write_collections, content,
user):
def do_MKCOL(self, environ, path, content, user):
"""Manage MKCOL request."""
if not write_collections:
if not self.authorized(user, path, "w"):
return NOT_ALLOWED
with self._lock_collection("w", user):
item = next(self.Collection.discover(path, depth="0"), None)
if item:
return client.CONFLICT, {}, None
props = xmlutils.props_from_request(content)
collection = self.Collection.create_collection(path, props=props)
for key, value in props.items():
collection.set_meta(key, value)
return client.CREATED, {}, None
collection = write_collections[0]
props = xmlutils.props_from_request(content)
collection = self.Collection.create_collection(
environ["PATH_INFO"], props=props)
return client.CREATED, {}, None
def do_MOVE(self, environ, read_collections, write_collections, content,
user):
def do_MOVE(self, environ, path, content, user):
"""Manage MOVE request."""
if not write_collections:
to_url = urlparse(environ["HTTP_DESTINATION"])
if to_url.netloc != environ["HTTP_HOST"]:
# Remote destination server, not supported
return client.BAD_GATEWAY, {}, None
to_path = storage.sanitize_path(to_url.path)
if (not self._access(user, path, "w") or
not self._access(user, to_path, "w")):
return NOT_ALLOWED
with self._lock_collection("w", user):
item = next(self.Collection.discover(path, depth="0"), None)
if (not self._access(user, path, "w", item) or
not self._access(user, to_path, "w", item)):
return NOT_ALLOWED
if not item:
return client.GONE, {}, None
to_item = next(self.Collection.discover(to_path, depth="0"), None)
to_parent_path = storage.sanitize_path(
"/%s/" % posixpath.dirname(to_path.strip("/")))
to_href = posixpath.basename(to_path.strip("/"))
to_collection = next(self.Collection.discover(
to_parent_path, depth="0"), None)
print(path, isinstance(item, self.Collection))
if (isinstance(item, self.Collection) or not to_collection or
to_item or to_path.strip("/").startswith(path.strip("/"))):
return client.CONFLICT, {}, None
to_collection.upload(to_href, item.item)
item.collection.delete(item.href)
return client.CREATED, {}, None
from_collection = write_collections[0]
from_name = xmlutils.name_from_path(
environ["PATH_INFO"], from_collection)
item = from_collection.get(from_name)
if item:
# Move the item
to_url_parts = urlparse(environ["HTTP_DESTINATION"])
if to_url_parts.netloc == environ["HTTP_HOST"]:
to_url = to_url_parts.path
to_path, to_name = to_url.rstrip("/").rsplit("/", 1)
for to_collection in self.Collection.discover(
to_path, depth="0"):
if to_collection in write_collections:
to_collection.upload(to_name, item)
from_collection.delete(from_name)
return client.CREATED, {}, None
else:
return NOT_ALLOWED
else:
# Remote destination server, not supported
return client.BAD_GATEWAY, {}, None
else:
# No item found
return client.GONE, {}, None
def do_OPTIONS(self, environ, read_collections, write_collections,
content, user):
def do_OPTIONS(self, environ, path, content, user):
"""Manage OPTIONS request."""
headers = {
"Allow": ("DELETE, HEAD, GET, MKCALENDAR, MKCOL, MOVE, "
@ -540,94 +497,100 @@ class Application:
"DAV": "1, 2, 3, calendar-access, addressbook, extended-mkcol"}
return client.OK, headers, None
def do_PROPFIND(self, environ, read_collections, write_collections,
content, user):
def do_PROPFIND(self, environ, path, content, user):
"""Manage PROPFIND request."""
if not read_collections:
return (client.NOT_FOUND, {}, None) if user else NOT_ALLOWED
headers = {
"DAV": "1, 2, 3, calendar-access, addressbook, extended-mkcol",
"Content-Type": "text/xml"}
answer = xmlutils.propfind(
environ["PATH_INFO"], content, read_collections, write_collections,
user)
return client.MULTI_STATUS, headers, answer
with self._lock_collection("r", user):
items = self.Collection.discover(path,
environ.get("HTTP_DEPTH", "0"))
read_items, write_items = self.collect_allowed_items(items, user)
if not read_items and not write_items:
return (client.NOT_FOUND, {}, None) if user else NOT_ALLOWED
headers = {
"DAV": "1, 2, 3, calendar-access, addressbook, extended-mkcol",
"Content-Type": "text/xml"}
answer = xmlutils.propfind(
path, content, read_items, write_items, user)
return client.MULTI_STATUS, headers, answer
def do_PROPPATCH(self, environ, read_collections, write_collections,
content, user):
def do_PROPPATCH(self, environ, path, content, user):
"""Manage PROPPATCH request."""
if not write_collections:
if not self.authorized(user, path, "w"):
return NOT_ALLOWED
with self._lock_collection("w", user):
item = next(self.Collection.discover(path, depth="0"), None)
if not isinstance(item, self.Collection):
return client.CONFLICT, {}, None
answer = xmlutils.proppatch(path, content, item)
headers = {
"DAV": "1, 2, 3, calendar-access, addressbook, extended-mkcol",
"Content-Type": "text/xml"}
return client.MULTI_STATUS, headers, answer
collection = write_collections[0]
answer = xmlutils.proppatch(environ["PATH_INFO"], content, collection)
headers = {
"DAV": "1, 2, 3, calendar-access, addressbook, extended-mkcol",
"Content-Type": "text/xml"}
return client.MULTI_STATUS, headers, answer
def do_PUT(self, environ, read_collections, write_collections, content,
user):
def do_PUT(self, environ, path, content, user):
"""Manage PUT request."""
if not write_collections:
if not self._access(user, path, "w"):
return NOT_ALLOWED
collection = write_collections[0]
with self._lock_collection("w", user):
parent_path = storage.sanitize_path(
"/%s/" % posixpath.dirname(path.strip("/")))
item = next(self.Collection.discover(path, depth="0"), None)
parent_item = next(self.Collection.discover(
parent_path, depth="0"), None)
write_whole_collection = (
isinstance(item, self.Collection) or
not parent_item or
not next(parent_item.list(), None) and
parent_item.get_meta("tag") not in (
"VADDRESSBOOK", "VCALENDAR"))
if (write_whole_collection and
not self.authorized(user, path, "w") or
not write_whole_collection and
not self.authorized(user, parent_path, "w")):
return NOT_ALLOWED
etag = environ.get("HTTP_IF_MATCH", "")
match = environ.get("HTTP_IF_NONE_MATCH", "") == "*"
content_type = environ.get("CONTENT_TYPE")
if content_type:
tags = {value: key for key, value in storage.MIMETYPES.items()}
tag = tags.get(content_type.split(";")[0])
if tag:
collection.set_meta({"tag": tag})
headers = {}
item_name = xmlutils.name_from_path(environ["PATH_INFO"], collection)
item = collection.get(item_name)
if ((not item and etag) or (item and etag and item.etag != etag) or
(item and match)):
return client.PRECONDITION_FAILED, {}, None
etag = environ.get("HTTP_IF_MATCH", "")
match = environ.get("HTTP_IF_NONE_MATCH", "") == "*"
if (not item and not etag) or (
item and ((etag or item.etag) == item.etag) and not match):
# PUT allowed in 3 cases
# Case 1: No item and no ETag precondition: Add new item
# Case 2: Item and ETag precondition verified: Modify item
# Case 3: Item and no Etag precondition: Force modifying item
items = list(vobject.readComponents(content or ""))
if item:
# PUT is modifying an existing item
if items:
new_item = collection.update(item_name, items[0])
else:
new_item = None
elif item_name:
# PUT is adding a new item
if items:
new_item = collection.upload(item_name, items[0])
else:
new_item = None
content_type = environ.get("CONTENT_TYPE")
tag = None
if content_type:
tags = {value: key for key, value in storage.MIMETYPES.items()}
tag = tags.get(content_type.split(";")[0])
if write_whole_collection:
if item:
# Delete old collection
item.delete()
new_item = self.Collection.create_collection(path, items, tag)
else:
# PUT is replacing the whole collection
collection.delete()
new_item = self.Collection.create_collection(
environ["PATH_INFO"], items)
if new_item:
headers["ETag"] = new_item.etag
status = client.CREATED
else:
# PUT rejected in all other cases
status = client.PRECONDITION_FAILED
return status, headers, None
if tag:
parent_item.set_meta({"tag": tag})
href = posixpath.basename(path.strip("/"))
if item:
new_item = parent_item.update(href, items[0])
else:
new_item = parent_item.upload(href, items[0])
headers = {"ETag": new_item.etag}
return client.CREATED, headers, None
def do_REPORT(self, environ, read_collections, write_collections, content,
user):
def do_REPORT(self, environ, path, content, user):
"""Manage REPORT request."""
if not read_collections:
if not self._access(user, path, "w"):
return NOT_ALLOWED
collection = read_collections[0]
headers = {"Content-Type": "text/xml"}
answer = xmlutils.report(environ["PATH_INFO"], content, collection)
return client.MULTI_STATUS, headers, answer
with self._lock_collection("r", user):
item = next(self.Collection.discover(path, depth="0"), None)
if not self._access(user, path, "w", item):
return NOT_ALLOWED
if not item:
return client.NOT_FOUND, {}, None
if isinstance(item, self.Collection):
collection = item
else:
collection = item.collection
headers = {"Content-Type": "text/xml"}
answer = xmlutils.report(path, content, collection)
return client.MULTI_STATUS, headers, answer

View File

@ -107,19 +107,17 @@ class Rights(BaseRights):
self.filename = os.path.expanduser(configuration.get("rights", "file"))
self.rights_type = configuration.get("rights", "type").lower()
def authorized(self, user, collection, permission):
def authorized(self, user, path, permission):
user = user or ""
if user and not storage.is_safe_path_component(user):
# Prevent usernames like "user/calendar.ics"
raise ValueError("Unsafe username")
collection_url = collection.path.rstrip("/")
if collection_url in (".well-known/carddav", ".well-known/caldav"):
return permission == "r"
sane_path = storage.sanitize_path(path).strip("/")
# Prevent "regex injection"
user_escaped = re.escape(user)
collection_url_escaped = re.escape(collection_url)
sane_path_escaped = re.escape(sane_path)
regex = ConfigParser(
{"login": user_escaped, "path": collection_url_escaped})
{"login": user_escaped, "path": sane_path_escaped})
if self.rights_type in DEFINED_RIGHTS:
self.logger.debug("Rights type '%s'" % self.rights_type)
regex.readfp(StringIO(DEFINED_RIGHTS[self.rights_type]))
@ -135,11 +133,11 @@ class Rights(BaseRights):
re_collection = regex.get(section, "collection")
self.logger.debug(
"Test if '%s:%s' matches against '%s:%s' from section '%s'" % (
user, collection_url, re_user, re_collection, section))
user, sane_path, re_user, re_collection, section))
user_match = re.fullmatch(re_user, user)
if user_match:
re_collection = re_collection.format(*user_match.groups())
if re.fullmatch(re_collection, collection_url):
if re.fullmatch(re_collection, sane_path):
self.logger.debug("Section '%s' matches" % section)
return permission in regex.get(section, "permission")
else:

View File

@ -229,9 +229,7 @@ class BaseCollection:
returned.
If ``depth`` is anything but "0", it is considered as "1" and direct
children are included in the result. If ``include_container`` is
``True`` (the default), the containing object is included in the
result.
children are included in the result.
The ``path`` is relative.
@ -398,41 +396,37 @@ class Collection(BaseCollection):
# Try to guess if the path leads to a collection or an item
folder = cls._get_collection_root_folder()
# HACK: Detection of principal collections fails if folder doesn't
# exist. This can be removed, when this method stop returning
# collections that don't exist.
os.makedirs(folder, exist_ok=True)
if not os.path.isdir(path_to_filesystem(folder, sane_path)):
# path is not a collection
if attributes and os.path.isfile(path_to_filesystem(folder,
sane_path)):
# path is an item
attributes.pop()
elif attributes and os.path.isdir(path_to_filesystem(
folder, *attributes[:-1])):
# path parent is a collection
attributes.pop()
# TODO: else: return?
try:
filesystem_path = path_to_filesystem(folder, sane_path)
except ValueError:
# Path is unsafe
return
href = None
if not os.path.isdir(filesystem_path):
if attributes and os.path.isfile(filesystem_path):
href = attributes.pop()
else:
return
path = "/".join(attributes)
principal = len(attributes) == 1
collection = cls(path, principal)
if href:
yield collection.get(href)
return
yield collection
if depth != "0":
# TODO: fix this
items = list(collection.list())
if items:
for item in items:
yield collection.get(item[0])
_, directories, _ = next(os.walk(collection._filesystem_path))
for sub_path in directories:
if not is_safe_filesystem_path_component(sub_path):
cls.logger.debug("Skipping collection: %s", sub_path)
continue
full_path = os.path.join(collection._filesystem_path, sub_path)
if os.path.exists(full_path):
yield cls(posixpath.join(path, sub_path))
if depth == "0":
return
for item in collection.list():
yield collection.get(item[0])
for href in os.listdir(filesystem_path):
if not is_safe_filesystem_path_component(href):
cls.logger.debug("Skipping collection: %s", href)
continue
child_filesystem_path = path_to_filesystem(filesystem_path, href)
if os.path.isdir(child_filesystem_path):
child_principal = len(attributes) == 0
yield cls(child_filesystem_path, child_principal)
@classmethod
def create_collection(cls, href, collection=None, props=None):

View File

@ -133,6 +133,36 @@ class BaseRequests:
status, headers, answer = self.request("GET", "/calendar.ics/")
assert "VEVENT" not in answer
def test_mkcalendar(self):
"""Make a calendar."""
self.request("MKCALENDAR", "/calendar.ics/")
status, headers, answer = self.request("GET", "/calendar.ics/")
assert status == 200
def test_move(self):
"""Move a item."""
self.request("MKCALENDAR", "/calendar.ics/")
event = get_file_content("event1.ics")
path1 = "/calendar.ics/event1.ics"
path2 = "/calendar.ics/event2.ics"
status, headers, answer = self.request("PUT", path1, event)
status, headers, answer = self.request(
"MOVE", path1, HTTP_DESTINATION=path2, HTTP_HOST="")
assert status == 201
status, headers, answer = self.request("GET", path1)
assert status == 404
status, headers, answer = self.request("GET", path2)
assert status == 200
def test_head(self):
status, headers, answer = self.request("HEAD", "/")
assert status == 200
def test_options(self):
status, headers, answer = self.request("OPTIONS", "/")
assert status == 200
assert "DAV" in headers
def test_multiple_events_with_same_uid(self):
"""Add two events with the same UID."""
self.request("MKCOL", "/calendar.ics/")

View File

@ -472,20 +472,13 @@ def props_from_request(root, actions=("set", "remove")):
return result
def delete(path, collection):
def delete(path, collection, href=None):
"""Read and answer DELETE requests.
Read rfc4918-9.6 for info.
"""
# Reading request
if collection.path == path.strip("/"):
# Delete the whole collection
collection.delete()
else:
# Remove an item from the collection
collection.delete(name_from_path(path, collection))
collection.delete(href)
# Writing answer
multistatus = ET.Element(_tag("D", "multistatus"))
response = ET.Element(_tag("D", "response"))