python/google/appengine/api/dosinfo.py

   1 #!/usr/bin/env python
   2 #
   3 # Copyright 2007 Google Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17
  18
  19
  20
  21 """DOS configuration tools.
  22
  23 Library for parsing dos.yaml files and working with these in memory.
  24 """
  25
  26
  27
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  29
  30
  31
  32
  33 import re
  34 import google
  35 import ipaddr
  36
  37 from google.appengine.api import appinfo
  38 from google.appengine.api import validation
  39 from google.appengine.api import yaml_builder
  40 from google.appengine.api import yaml_listener
  41 from google.appengine.api import yaml_object
  42
  43 _DESCRIPTION_REGEX = r'^.{0,499}$'
  44
  45 BLACKLIST = 'blacklist'
  46 DESCRIPTION = 'description'
  47 SUBNET = 'subnet'
  48
  49
  50 class SubnetValidator(validation.Validator):
  51   """Checks that a subnet can be parsed and is a valid IPv4 or IPv6 subnet."""
  52
  53   def Validate(self, value, unused_key=None):
  54     """Validates a subnet."""
  55     if value is None:
  56       raise validation.MissingAttribute('subnet must be specified')
  57     if not isinstance(value, basestring):
  58       raise validation.ValidationError('subnet must be a string, not \'%r\'' %
  59                                        type(value))
  60     try:
  61       ipaddr.IPNetwork(value)
  62     except ValueError:
  63       raise validation.ValidationError('%s is not a valid IPv4 or IPv6 subnet' %
  64                                        value)
  65
  66
  67     parts = value.split('/')
  68     if len(parts) == 2 and not re.match('^[0-9]+$', parts[1]):
  69       raise validation.ValidationError('Prefix length of subnet %s must be an '
  70                                        'integer (quad-dotted masks are not '
  71                                        'supported)' % value)
  72
  73     return value
  74
  75
  76 class MalformedDosConfiguration(Exception):
  77   """Configuration file for DOS API is malformed."""
  78
  79
  80 class BlacklistEntry(validation.Validated):
  81   """A blacklist entry describes a blocked IP address or subnet."""
  82   ATTRIBUTES = {
  83       DESCRIPTION: validation.Optional(_DESCRIPTION_REGEX),
  84       SUBNET: SubnetValidator(),
  85   }
  86
  87
  88 class DosInfoExternal(validation.Validated):
  89   """Describes the format of a dos.yaml file."""
  90   ATTRIBUTES = {
  91       appinfo.APPLICATION: validation.Optional(appinfo.APPLICATION_RE_STRING),
  92       BLACKLIST: validation.Optional(validation.Repeated(BlacklistEntry)),
  93   }
  94
  95
  96 def LoadSingleDos(dos_info, open_fn=None):
  97   """Load a dos.yaml file or string and return a DosInfoExternal object.
  98
  99   Args:
 100     dos_info: The contents of a dos.yaml file as a string, or an open file
 101       object.
 102     open_fn: Function for opening files. Unused.
 103
 104   Returns:
 105     A DosInfoExternal instance which represents the contents of the parsed yaml
 106     file.
 107
 108   Raises:
 109     MalformedDosConfiguration: The yaml file contains multiple blacklist
 110       sections.
 111     yaml_errors.EventError: An error occured while parsing the yaml file.
 112   """
 113   builder = yaml_object.ObjectBuilder(DosInfoExternal)
 114   handler = yaml_builder.BuilderHandler(builder)
 115   listener = yaml_listener.EventListener(handler)
 116   listener.Parse(dos_info)
 117
 118   parsed_yaml = handler.GetResults()
 119   if not parsed_yaml:
 120     return DosInfoExternal()
 121   if len(parsed_yaml) > 1:
 122     raise MalformedDosConfiguration('Multiple blacklist: sections '
 123                                     'in configuration.')
 124   return parsed_yaml[0]