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#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# 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.
#
"""DOS configuration tools.
Library for parsing dos.yaml files and working with these in memory.
"""
import google
import ipaddr
from google.appengine.api import validation
from google.appengine.api import yaml_builder
from google.appengine.api import yaml_listener
from google.appengine.api import yaml_object
_DESCRIPTION_REGEX = r'^.{0,499}$'
BLACKLIST = 'blacklist'
DESCRIPTION = 'description'
SUBNET = 'subnet'
class SubnetValidator(validation.Validator):
"""Checks that a subnet can be parsed and is a valid IPv4 or IPv6 subnet."""
def Validate(self, value, key=None):
"""Validates a subnet."""
if value is None:
raise validation.MissingAttribute('subnet must be specified')
try:
ipaddr.IPNetwork(value)
except ValueError:
raise validation.ValidationError('%s is not a valid IPv4 or IPv6 subnet' %
value)
else:
return value
class MalformedDosConfiguration(Exception):
"""Configuration file for DOS API is malformed."""
class BlacklistEntry(validation.Validated):
"""A blacklist entry descibes a blocked IP address or subnet."""
ATTRIBUTES = {
DESCRIPTION: validation.Optional(_DESCRIPTION_REGEX),
SUBNET: SubnetValidator(),
}
class DosInfoExternal(validation.Validated):
ATTRIBUTES = {
BLACKLIST: validation.Optional(validation.Repeated(BlacklistEntry)),
}
def LoadSingleDos(dos_info):
"""Load a dos.yaml file or string and return a DosInfoExternal object.
Args:
dos_info: The contents of a dos.yaml file, as a string.
Returns:
A DosInfoExternal instance which represents the contents of the parsed yaml
file.
Raises:
MalformedDosConfiguration if the yaml file contains multiple blacklist
sections.
yaml_errors.EventError if any errors occured while parsing the yaml file.
"""
builder = yaml_object.ObjectBuilder(DosInfoExternal)
handler = yaml_builder.BuilderHandler(builder)
listener = yaml_listener.EventListener(handler)
listener.Parse(dos_info)
dos_info = handler.GetResults()
if len(dos_info) < 1:
return DosInfoExternal()
if len(dos_info) > 1:
raise MalformedDosConfiguration('Multiple blacklist: sections '
'in configuration.')
return dos_info[0]
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