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# Copyright (C) 2010-2012 by the Free Software Foundation, Inc.
#
# This file is part of GNU Mailman.
#
# GNU Mailman 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.
#
# GNU Mailman 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
# GNU Mailman. If not, see <http://www.gnu.org/licenses/>.
"""Web service helpers."""
from __future__ import absolute_import, unicode_literals
__metaclass__ = type
__all__ = [
'GetterSetter',
'PATCH',
'etag',
'no_content',
'path_to',
'restish_matcher',
]
import cgi
import json
import hashlib
from cStringIO import StringIO
from datetime import datetime, timedelta
from flufl.enum import Enum
from lazr.config import as_boolean
from restish.http import Response
from restish.resource import MethodDecorator
from webob.multidict import MultiDict
from mailman.config import config
def path_to(resource):
"""Return the url path to a resource.
:param resource: The canonical path to the resource, relative to the
system base URI.
:type resource: string
:return: The full path to the resource.
:rtype: bytes
"""
return b'{0}://{1}:{2}/{3}/{4}'.format(
('https' if as_boolean(config.webservice.use_https) else 'http'),
config.webservice.hostname,
config.webservice.port,
config.webservice.api_version,
(resource[1:] if resource.startswith('/') else resource),
)
class ExtendedEncoder(json.JSONEncoder):
"""An extended JSON encoder which knows about other data types."""
def default(self, obj):
if isinstance(obj, datetime):
return obj.isoformat()
elif isinstance(obj, timedelta):
# as_timedelta() does not recognize microseconds, so convert these
# to floating seconds, but only if there are any seconds.
if obj.seconds > 0 or obj.microseconds > 0:
seconds = obj.seconds + obj.microseconds / 1000000.0
return '{0}d{1}s'.format(obj.days, seconds)
return '{0}d'.format(obj.days)
elif hasattr(obj, 'enum') and issubclass(obj.enum, Enum):
# It's up to the decoding validator to associate this name with
# the right Enum class.
return obj.name
return json.JSONEncoder.default(self, obj)
def etag(resource):
"""Calculate the etag and return a JSON representation.
The input is a dictionary representing the resource. This dictionary must
not contain an `http_etag` key. This function calculates the etag by
using the sha1 hexdigest of the repr of the dictionary. It then inserts
this value under the `http_etag` key, and returns the JSON representation
of the modified dictionary.
:param resource: The original resource representation.
:type resource: dictionary
:return: JSON representation of the modified dictionary.
:rtype string
"""
assert 'http_etag' not in resource, 'Resource already etagged'
etag = hashlib.sha1(repr(resource)).hexdigest()
resource['http_etag'] = '"{0}"'.format(etag)
return json.dumps(resource, cls=ExtendedEncoder)
class CollectionMixin:
"""Mixin class for common collection-ish things."""
def _resource_as_dict(self, resource):
"""Return the dictionary representation of a resource.
This must be implemented by subclasses.
:param resource: The resource object.
:type resource: object
:return: The representation of the resource.
:rtype: dict
"""
raise NotImplementedError
def _resource_as_json(self, resource):
"""Return the JSON formatted representation of the resource."""
return etag(self._resource_as_dict(resource))
def _get_collection(self, request):
"""Return the collection as a concrete list.
This must be implemented by subclasses.
:param request: A restish request.
:return: The collection
:rtype: list
"""
raise NotImplementedError
def _make_collection(self, request):
"""Provide the collection to restish."""
collection = self._get_collection(request)
if len(collection) == 0:
return dict(start=0, total_size=0)
else:
entries = [self._resource_as_dict(resource)
for resource in collection]
# Tag the resources but use the dictionaries.
[etag(resource) for resource in entries]
# Create the collection resource
return dict(
start=0,
total_size=len(collection),
entries=entries,
)
# XXX 2010-02-24 barry Seems like contrary to the documentation, matchers
# cannot be plain functions, because matchers must have a .score attribute.
# OTOH, I think they support regexps, so that might be a better way to go.
def restish_matcher(function):
"""Decorator for restish matchers."""
function.score = ()
return function
# restish doesn't support HTTP response code 204.
def no_content():
"""204 No Content."""
return Response('204 No Content', [], None)
# These two classes implement an ugly, dirty hack to work around the fact that
# neither WebOb nor really the stdlib cgi module support non-standard HTTP
# verbs such as PATCH. Note that restish handles it just fine in the sense
# that the right method gets called, but without the following kludge, the
# body of the request will never get decoded, so the method won't see any
# data.
#
# Stuffing the MultiDict on request.PATCH is pretty ugly, but it mirrors
# WebOb's use of request.POST and request.PUT for those standard verbs.
# Besides, WebOb refuses to allow us to set request.POST. This does make
# validators.py a bit more complicated. :(
class PATCHWrapper:
"""Hack to decode the request body for PATCH."""
def __init__(self, func):
self.func = func
def __call__(self, resource, request):
# We can't use request.body_file because that's a socket that's
# already had its data read off of. IOW, if we use that directly,
# we'll block here.
field_storage = cgi.FieldStorage(
fp=StringIO(request.body),
# Yes, lie about the method so cgi will do the right thing.
environ=dict(REQUEST_METHOD='POST'),
keep_blank_values=True)
request.PATCH = MultiDict.from_fieldstorage(field_storage)
return self.func(resource, request)
class PATCH(MethodDecorator):
method = 'PATCH'
def __call__(self, func):
really_wrapped_func = PATCHWrapper(func)
return super(PATCH, self).__call__(really_wrapped_func)
class GetterSetter:
"""Get and set attributes on an object.
Most attributes are fairly simple - a getattr() or setattr() on the object
does the trick, with the appropriate encoding or decoding on the way in
and out. Encoding doesn't happen here though; the standard JSON library
handles most types, but see ExtendedEncoder for additional support.
Others are more complicated since they aren't kept in the model as direct
columns in the database. These will use subclasses of this base class.
Read-only attributes will have a decoder which always raises ValueError.
"""
def __init__(self, decoder=None):
"""Create a getter/setter for a specific attribute.
:param decoder: The callable for decoding a web request value string
into the specific data type needed by the object's attribute. Use
None to indicate a read-only attribute. The callable should raise
ValueError when the web request value cannot be converted.
:type decoder: callable
"""
self.decoder = decoder
def get(self, obj, attribute):
"""Return the named object attribute value.
:param obj: The object to access.
:type obj: object
:param attribute: The attribute name.
:type attribute: string
:return: The attribute value, ready for JSON encoding.
:rtype: object
"""
return getattr(obj, attribute)
def put(self, obj, attribute, value):
"""Set the named object attribute value.
:param obj: The object to change.
:type obj: object
:param attribute: The attribute name.
:type attribute: string
:param value: The new value for the attribute.
"""
setattr(obj, attribute, value)
def __call__(self, value):
"""Convert the value to its internal format.
:param value: The web request value to convert.
:type value: string
:return: The converted value.
:rtype: object
"""
if self.decoder is None:
return value
return self.decoder(value)
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