class Bones::RPC::DNSResolver
Constants
- DNS_PORT
- RESOLV_CONF
Public Class Methods
generate_id()
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# File lib/bones/rpc/dns_resolver.rb, line 12 def self.generate_id @mutex.synchronize { @identifier = (@identifier + 1) & 0xFFFF } end
nameservers(config = RESOLV_CONF)
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# File lib/bones/rpc/dns_resolver.rb, line 16 def self.nameservers(config = RESOLV_CONF) File.read(config).scan(/^\s*nameserver\s+([0-9.:]+)/).flatten end
new()
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# File lib/bones/rpc/dns_resolver.rb, line 20 def initialize @nameservers = self.class.nameservers # TODO: fall back on other nameservers if the first one is unavailable @server = @nameservers.first @socket = UDPSocket.new end
Public Instance Methods
resolve(hostname)
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# File lib/bones/rpc/dns_resolver.rb, line 29 def resolve(hostname) if host = resolve_hostname(hostname) unless ip_address = resolve_host(host) raise Resolv::ResolvError, "invalid entry in hosts file: #{host}" end return ip_address end query = build_query(hostname) @socket.send query.encode, 0, @server, DNS_PORT data, _ = @socket.recvfrom(512) 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/bones/rpc/dns_resolver.rb, line 65 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
resolv()
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# File lib/bones/rpc/dns_resolver.rb, line 61 def resolv @resolv ||= Resolv::Hosts.new end
resolve_host(host)
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# File lib/bones/rpc/dns_resolver.rb, line 73 def resolve_host(host) resolve_ip(Resolv::IPv4, host) || resolve_ip(Resolv::IPv6, host) end
resolve_hostname(hostname)
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# File lib/bones/rpc/dns_resolver.rb, line 54 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 nil end
resolve_ip(klass, host)
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# File lib/bones/rpc/dns_resolver.rb, line 77 def resolve_ip(klass, host) begin klass.create(host) rescue ArgumentError end end