"""
Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and associated documentation files (the "Software"), to deal in the Software
without restriction, including without limitation the rights to use, copy, modify,
merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
"""
import re
import six
from cfnlint import CloudFormationLintRule
from cfnlint import RuleMatch
from cfnlint.helpers import REGEX_CIDR
class Cidr(CloudFormationLintRule):
"""Check if Cidr values are correct"""
id = 'E1024'
shortdesc = 'Cidr validation of parameters'
description = 'Making sure the function CIDR is a list with valid values'
source_url = 'https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference-cidr.html'
tags = ['functions', 'cidr']
def check_parameter_count(self, cfn, parameter_name):
"""Check Count Parameter if used"""
matches = []
parameter_obj = cfn.get_parameters().get(parameter_name, {})
if parameter_obj:
tree = ['Parameters', parameter_name]
parameter_type = parameter_obj.get('Type')
if parameter_type == 'Number':
max_value = parameter_obj.get('MaxValue')
min_value = parameter_obj.get('MinValue')
if (not min_value) or min_value < 1 or min_value > 256:
message = 'Parameter for Cidr count have MinValue between 1 and 256 at {0}'
matches.append(RuleMatch(
tree + ['MinValue'], message.format('/'.join(map(str, tree + ['MinValue'])))))
if (not max_value) or max_value < 1 or max_value > 256:
message = 'Parameter for Cidr count have MaxValue between 1 and 256 at {0}'
matches.append(RuleMatch(
tree + ['MaxValue'], message.format('/'.join(map(str, tree + ['MaxValue'])))))
else:
message = 'Parameter for Cidr count have be of Type Number at {0}'
matches.append(RuleMatch(
tree, message.format('/'.join(map(str, tree)))))
return matches
def check_parameter_size_mask(self, cfn, parameter_name):
"""Check SizeMask Parameter if used"""
matches = []
parameter_obj = cfn.get_parameters().get(parameter_name, {})
if parameter_obj:
tree = ['Parameters', parameter_name]
parameter_type = parameter_obj.get('Type')
if parameter_type == 'Number':
max_value = parameter_obj.get('MaxValue')
min_value = parameter_obj.get('MinValue')
if (not min_value) or min_value < 1 or min_value > 256:
message = 'Parameter for Cidr sizeMask have MinValue between 1 and ' \
'128 (for ipv6) and 32 (for ipv4) at {0}'
matches.append(RuleMatch(
tree + ['MinValue'], message.format('/'.join(map(str, tree + ['MinValue'])))))
if (not max_value) or max_value < 1 or max_value > 256:
message = 'Parameter for Cidr count have MaxValue between 1 and ' \
'128 (for ipv6) and 32 (for ipv4) at {0}'
matches.append(RuleMatch(
tree + ['MaxValue'], message.format('/'.join(map(str, tree + ['MaxValue'])))))
else:
message = 'Parameter for Cidr count have be of Type Number at {0}'
matches.append(RuleMatch(
tree, message.format('/'.join(map(str, tree)))))
return matches
def match(self, cfn):
"""Check CloudFormation Cidr"""
matches = []
cidr_objs = cfn.search_deep_keys('Fn::Cidr')
supported_functions = [
'Fn::Select',
'Ref',
'Fn::GetAtt',
'Fn::Sub',
'Fn::ImportValue'
]
count_parameters = []
size_mask_parameters = []
for cidr_obj in cidr_objs:
cidr_value_obj = cidr_obj[-1]
tree = cidr_obj[:-1]
if isinstance(cidr_value_obj, list):
if len(cidr_value_obj) in [2, 3]:
ip_block_obj = cidr_value_obj[0]
count_obj = cidr_value_obj[1]
if len(cidr_value_obj) == 3:
size_mask_obj = cidr_value_obj[2]
else:
size_mask_obj = None
if isinstance(ip_block_obj, dict):
if len(ip_block_obj) == 1:
for index_key, _ in ip_block_obj.items():
if index_key not in supported_functions:
message = 'Cidr ipBlock should be Cidr Range, Ref, GetAtt, Sub or Select for {0}'
matches.append(RuleMatch(
tree[:] + [0], message.format('/'.join(map(str, tree[:] + [0])))))
elif isinstance(ip_block_obj, (six.text_type, six.string_types)):
if not re.match(REGEX_CIDR, ip_block_obj):
message = 'Cidr ipBlock should be a Cidr Range based string for {0}'
matches.append(RuleMatch(
tree[:] + [0], message.format('/'.join(map(str, tree[:] + [0])))))
else:
message = 'Cidr ipBlock should be a string for {0}'
matches.append(RuleMatch(
tree[:] + [0], message.format('/'.join(map(str, tree[:] + [0])))))
if isinstance(count_obj, dict):
if len(count_obj) == 1:
for index_key, index_value in count_obj.items():
if index_key not in supported_functions:
message = 'Cidr count should be Int, Ref, or Select for {0}'
matches.append(RuleMatch(
tree[:] + [1], message.format('/'.join(map(str, tree[:] + [1])))))
if index_key == 'Ref':
count_parameters.append(index_value)
elif not isinstance(count_obj, six.integer_types):
message = 'Cidr count should be a int for {0}'
matches.append(RuleMatch(
tree[:] + [1], message.format('/'.join(map(str, tree[:] + [1])))))
if isinstance(size_mask_obj, dict):
if len(size_mask_obj) == 1:
for index_key, index_value in size_mask_obj.items():
if index_key not in supported_functions:
message = 'Cidr sizeMask should be Int, Ref, or Select for {0}'
matches.append(RuleMatch(
tree[:] + [2], message.format('/'.join(map(str, tree[:] + [2])))))
if index_key == 'Ref':
size_mask_parameters.append(index_value)
elif not isinstance(size_mask_obj, six.integer_types):
message = 'Cidr sizeMask should be a int for {0}'
matches.append(RuleMatch(
tree[:] + [2], message.format('/'.join(map(str, tree[:] + [2])))))
else:
message = 'Cidr should be a list of 2 or 3 elements for {0}'
matches.append(RuleMatch(
tree, message.format('/'.join(map(str, tree)))))
else:
message = 'Cidr should be a list of 2 or 3 elements for {0}'
matches.append(RuleMatch(
tree, message.format('/'.join(map(str, tree)))))
for count_parameter in set(count_parameters):
matches.extend(self.check_parameter_count(cfn, count_parameter))
for size_mask_parameter in set(size_mask_parameters):
matches.extend(self.check_parameter_size_mask(cfn, size_mask_parameter))
return matches