class Celluloid::IO::DNSResolver
Asynchronous DNS resolver using Celluloid::IO::UDPSocket
Constants
- DNS_PORT
- MAX_PACKET_SIZE
Maximum UDP packet we'll accept
Public Class Methods
generate_id()
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# File lib/celluloid/io/dns_resolver.rb, line 15 def self.generate_id @mutex.synchronize { @identifier = (@identifier + 1) & 0xFFFF } end
nameservers()
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# File lib/celluloid/io/dns_resolver.rb, line 19 def self.nameservers Resolv::DNS::Config.default_config_hash[:nameserver] end
new()
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# File lib/celluloid/io/dns_resolver.rb, line 23 def initialize # early return for edge case when there are no nameservers configured # but we still want to be able to static lookups using #resolve_hostname @nameservers = self.class.nameservers or return @server = IPAddr.new(@nameservers.sample) # The non-blocking secret sauce is here, as this is actually a # Celluloid::IO::UDPSocket @socket = UDPSocket.new(@server.family) end
Public Instance Methods
resolve(hostname)
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# File lib/celluloid/io/dns_resolver.rb, line 35 def resolve(hostname) if host = resolve_hostname(hostname) unless ip_address = resolve_host(host) fail Resolv::ResolvError, "invalid entry in hosts file: #{host}" end return ip_address end query = build_query(hostname) @socket.send query.encode, 0, @server.to_s, DNS_PORT data, _ = @socket.recvfrom(MAX_PACKET_SIZE) response = Resolv::DNS::Message.decode(data) addrs = [] # The answer might include IN::CNAME entries so filters them out # to include IN::A & IN::AAAA entries only. response.each_answer { |name, ttl, value| addrs << value.address if value.respond_to?(:address) } return if addrs.empty? return addrs.first if addrs.size == 1 addrs end
Private Instance Methods
build_query(hostname)
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# File lib/celluloid/io/dns_resolver.rb, line 72 def build_query(hostname) Resolv::DNS::Message.new.tap do |query| query.id = self.class.generate_id query.rd = 1 query.add_question hostname, Resolv::DNS::Resource::IN::A end end
get_address(host)
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# File lib/celluloid/io/dns_resolver.rb, line 91 def get_address(host) Resolv::Hosts.new(host).getaddress rescue end
resolv()
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# File lib/celluloid/io/dns_resolver.rb, line 68 def resolv @resolv ||= Resolv::Hosts.new end
resolve_host(host)
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# File lib/celluloid/io/dns_resolver.rb, line 80 def resolve_host(host) resolve_ip(Resolv::IPv4, host) || get_address(host) || resolve_ip(Resolv::IPv6, host) end
resolve_hostname(hostname)
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# File lib/celluloid/io/dns_resolver.rb, line 60 def resolve_hostname(hostname) # Resolv::Hosts#getaddresses pushes onto a stack # so since we want the first occurance, simply # pop off the stack. resolv.getaddresses(hostname).pop rescue end
resolve_ip(klass, host)
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# File lib/celluloid/io/dns_resolver.rb, line 84 def resolve_ip(klass, host) klass.create(host) rescue ArgumentError end