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require "./rr"
require "./settings"
require "./response"
module AsyncDNS
class Resolver
getter settings : Settings
enum Error
NO_NAME_SERVER
end
private record Context, id : UInt16, settings : Settings,
block : Response | Error ->
def initialize
@settings = Settings.new
@queries = Hash(UInt16, Context).new
@tcp_queries = Hash(Socket, Context).new
end
def resolve(query : Query, &block : Response | Error ->)
id : UInt16
while true
id = Random::Secure.rand(UInt16::MIN..UInt16::MAX)
break unless @queries.has_key?(id)
end
if @settings.nameservers.empty?
yield Error::NO_NAME_SERVER
return
end
send(Context.new(id, settings.dup, block))
end
private def send(context : Context)
@queries[context.@id] = context
# TODO
end
def stop
# TODO
end
end
end
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require "socket"
require "./query"
require "./response"
require "./rr"
require "./settings"
module AsyncDNS
class Resolver
@v6_sock : UDPSocket?
@v4_sock : UDPSocket?
getter settings : Settings
enum Error
NO_NAME_SERVER
end
private class Context
getter query : Query
getter id : UInt16
getter settings : Settings
getter block : Response | Error ->
property ns_index : Int32
property attempt : Int32
property used_ns : Socket::IPAddress | Nil
getter raw_data : Bytes
def initialize(@query : Query, @id : UInt16, @settings : Settings,
@block : Response | Error ->)
@ns_index = 0
@attempt = 0
@used_ns = nil
@raw_data = Bytes.new(512)
# Header
i = 0
@raw_data[i] = (@id >> 8).to_u8; i += 1
@raw_data[i] = (@id & 0xFF).to_u8; i += 1
# RD
@raw_data[i] = 1; i += 1
i += 1
# QDCOUNT
i += 1
@raw_data[i] = 1; i += 1
# ANCOUNT, NSCOUNT and ARCOUNT
i += 6
# Question
# QNAME
@query.domain.split('.').each do |component|
if component.bytesize > 63 || i + component.bytesize > 512
raise ArgumentError.new("Domain component too long")
end
raw_component = component.to_slice
@raw_data[i] = raw_component.bytesize.to_u8; i += 1
@raw_data[i, raw_component.bytesize].copy_from(raw_component)
i += raw_component.bytesize
end
# QTYPE
qtype = @query.rr_type.to_i
@raw_data[i] = (qtype >> 8).to_u8; i += 1
@raw_data[i] = (qtype & 0xFF).to_u8; i+= 1
# QCLASS
qclass = @query.dns_class.to_i
@raw_data[i] = (qclass >> 8).to_u8; i += 1
@raw_data[i] = (qclass & 0xFF).to_u8; i += 1
end
end
def initialize
@settings = Settings.new
@queries = Hash(UInt16, Context).new
@tcp_queries = Hash(Socket, Context).new
end
def resolve(query : Query, &block : Response | Error ->) : Nil
id : UInt16
while true
id = Random::Secure.rand(UInt16::MIN..UInt16::MAX)
break unless @queries.has_key?(id)
end
if query.domain.bytesize > 253
raise ArgumentError.new("Queried domain is too long")
end
if @settings.nameservers.empty?
block.call(Error::NO_NAME_SERVER)
return
end
send(Context.new(query.dup, id, settings.dup, block))
end
private def send(context : Context) : Nil
@queries[context.id] = context
ns = context.settings.nameservers[context.ns_index]
context.used_ns = used_ns = Socket::IPAddress.new(ns, 53)
sock : UDPSocket
case used_ns.family
when Socket::Family::INET6
if @v6_sock.nil?
@v6_sock = s = UDPSocket.new
s.bind "::", 0
end
sock = @v6_sock.not_nil!
when Socket::Family::INET
if @v4_sock.nil?
@v4_sock = s = UDPSocket.new
s.bind "0.0.0.0", 0
end
sock = @v4_sock.not_nil!
else
raise ArgumentError.new("Nameserver must be INET or INET6")
end
sock.send(context.raw_data, used_ns)
end
def stop : Nil
# TODO
end
end
end
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