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# frozen_string_literal: true
# rubocop:todo all
# Copyright (C) 2017-2020 MongoDB 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.
module Mongo
module Srv
# SRV record lookup result.
#
# Contains server addresses that the query resolved to, and minimum TTL
# of the DNS records.
#
# @api private
class Result
include Address::Validator
# @return [ String ] MISMATCHED_DOMAINNAME Error message format string indicating that an SRV
# record found does not match the domain of a hostname.
MISMATCHED_DOMAINNAME = "Parent domain name in SRV record result (%s) does not match " +
"that of the hostname (%s)".freeze
# @return [ String ] query_hostname The hostname pointing to the DNS records.
attr_reader :query_hostname
# @return [ Array<String> ] address_strs The host strings of the SRV records
# for the query hostname.
attr_reader :address_strs
# @return [ Integer | nil ] min_ttl The smallest TTL found among the
# records (or nil if no records have been added).
attr_accessor :min_ttl
# Create a new object to keep track of the SRV records of the hostname.
#
# @param [ String ] hostname The hostname pointing to the DNS records.
def initialize(hostname)
@query_hostname = hostname
@address_strs = []
@min_ttl = nil
end
# Checks whether there are any records.
#
# @return [ Boolean ] Whether or not there are any records.
def empty?
@address_strs.empty?
end
# Adds a new record.
#
# @param [ Resolv::DNS::Resource ] record An SRV record found for the hostname.
def add_record(record)
record_host = normalize_hostname(record.target.to_s)
port = record.port
validate_hostname!(record_host)
validate_same_origin!(record_host)
address_str = if record_host.index(':')
# IPV6 address
"[#{record_host}]:#{port}"
else
"#{record_host}:#{port}"
end
@address_strs << address_str
if @min_ttl.nil?
@min_ttl = record.ttl
else
@min_ttl = [@min_ttl, record.ttl].min
end
nil
end
private
# Transforms the provided hostname to simplify its validation later on.
#
# This method is safe to call during both initial DNS seed list discovery
# and during SRV monitoring, in that it does not convert invalid hostnames
# into valid ones.
#
# - Converts the hostname to lower case.
# - Removes one trailing dot, if there is exactly one. If the hostname
# has multiple trailing dots, it is unchanged.
#
# @param [ String ] host Hostname to transform.
def normalize_hostname(host)
host = host.downcase
unless host.end_with?('..')
host = host.sub(/\.\z/, '')
end
host
end
# Ensures that a record's domain name matches that of the hostname.
#
# A hostname's domain name consists of each of the '.' delineated
# parts after the first. For example, the hostname 'foo.bar.baz'
# has the domain name 'bar.baz'.
#
# If the hostname has less than three parts, its domain name is the hostname itself.
#
# @param [ String ] record_host The host of the SRV record.
#
# @raise [ Mongo::Error::MismatchedDomain ] If the record's domain name doesn't match that of
# the hostname.
def validate_same_origin!(record_host)
srv_host_domain = query_hostname.split('.')
srv_is_less_than_three_parts = srv_host_domain.length < 3
unless srv_is_less_than_three_parts
srv_host_domain = srv_host_domain[1..-1]
end
record_host_parts = record_host.split('.')
if (srv_is_less_than_three_parts && record_host_parts.length <= srv_host_domain.length)
raise Error::MismatchedDomain.new(MISMATCHED_DOMAINNAME % [record_host, srv_host_domain])
end
unless (record_host_parts.size > srv_host_domain.size) && (srv_host_domain == record_host_parts[-srv_host_domain.size..-1])
raise Error::MismatchedDomain.new(MISMATCHED_DOMAINNAME % [record_host, srv_host_domain])
end
end
end
end
end
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