Class: HTTPX::Resolver::Native

Inherits:
Resolver
  • Object
show all
Extended by:
Forwardable
Includes:
_ToIO
Defined in:
lib/httpx/resolver/native.rb,
sig/resolver/native.rbs

Overview

Implements a pure ruby name resolver, which abides by the Selectable API. It delegates DNS payload encoding/decoding to the resolv stlid gem.

Constant Summary collapse

DEFAULTS =

Returns:

  • (Hash[Symbol, untyped]) 
{
  nameserver: nil,
  **Resolv::DNS::Config.default_config_hash,
  packet_size: 512,
  timeouts: Resolver::RESOLVE_TIMEOUT,
}.freeze
DNS_PORT =

Returns:

  • (Integer) 
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Constants inherited from Resolver

Resolver::FAMILY_TYPES, Resolver::RECORD_TYPES

Constants included from Loggable

Loggable::COLORS, Loggable::USE_DEBUG_LOG

Instance Attribute Summary collapse

Attributes inherited from Resolver

#current_selector, #current_session, #family, #multi, #options

Instance Method Summary collapse

Methods inherited from Resolver

#disconnect, #each_connection, #early_resolve, #emit_addresses, #emit_connection_error, #emit_resolve_error, #emit_resolved_connection, #empty?, #inflight?, #initial_call, #lazy_resolve, multi?, #on_error, #resolve_connection, #resolve_error

Methods included from Loggable

#log, #log_exception, log_identifiers, #log_redact, #log_redact_body, #log_redact_headers

Methods included from _Selectable

#initial_call, #on_error

Constructor Details

#initialize(family, options) ⇒ Native

Returns a new instance of Native.

Parameters:

  • family (ip_family)
  • options (options) 


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# File 'lib/httpx/resolver/native.rb', line 28

def initialize(family, options)
  super
  @ns_index = 0
  @resolver_options = DEFAULTS.merge(@options.resolver_options)
  @socket_type = @resolver_options.fetch(:socket_type, :udp)
  @nameserver = if (nameserver = @resolver_options[:nameserver])
    nameserver = nameserver[family] if nameserver.is_a?(Hash)
    Array(nameserver)
  end
  @ndots = @resolver_options.fetch(:ndots, 1)
  @search = Array(@resolver_options[:search]).map { |srch| srch.scan(/[^.]+/) }
  @_timeouts = Array(@resolver_options[:timeouts])
  @timeouts = Hash.new { |timeouts, host| timeouts[host] = @_timeouts.dup }
  @name = nil
  @queries = {}
  @read_buffer = "".b
  @write_buffer = Buffer.new(@resolver_options[:packet_size])
  @state = :idle
  @timer = nil
end

Instance Attribute Details

#state ⇒ Symbol (readonly)

Returns the value of attribute state.

Returns:

  • (Symbol) 


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# File 'lib/httpx/resolver/native.rb', line 26

def state
  @state
end

Instance Method Details

#<<(connection) ⇒ void

This method returns an undefined value.

Parameters:



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# File 'lib/httpx/resolver/native.rb', line 102

def <<(connection)
  if @nameserver.nil?
    ex = ResolveError.new("No available nameserver")
    ex.set_backtrace(caller)
    connection.force_close
    throw(:resolve_error, ex)
  else
    @connections << connection
    resolve
  end
end

#build_socket ⇒ UDP, TCP

Returns:



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# File 'lib/httpx/resolver/native.rb', line 499

def build_socket
  ip, port = @nameserver[@ns_index]
  port ||= DNS_PORT

  case @socket_type
  when :udp
    log { "resolver #{FAMILY_TYPES[@record_type]}: server: udp://#{ip}:#{port}..." }
    UDP.new(ip, port, @options)
  when :tcp
    log { "resolver #{FAMILY_TYPES[@record_type]}: server: tcp://#{ip}:#{port}..." }
    origin = URI("tcp://#{ip}:#{port}")
    TCP.new(origin, [Resolver::Entry.new(ip)], @options)
  end
end

#calculate_interests ⇒ :r, ...

Returns:

  • (:r, :w, nil) 


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# File 'lib/httpx/resolver/native.rb', line 145

def calculate_interests
  if @queries.empty?
    return @io.interests if (@socket_type == :tcp) && (@state == :idle)

    return
  end

  return :r if @write_buffer.empty?

  :w
end

#call ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 76

def call
  case @state
  when :idle, :closed
    return if @connections.empty?

    transition(:idle) if @state == :closed
    transition(:open)

    consume if @state == :open
  when :open
    consume
  end
end

#close ⇒ Object 



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# File 'lib/httpx/resolver/native.rb', line 49

def close
  transition(:closed)
end

#close_or_resolve ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 588

def close_or_resolve
  # drop already closed connections
  @connections.shift until @connections.empty? || @connections.first.state != :closed

  if (@connections - @queries.values).empty?
    disconnect
  else
    resolve
  end
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/httpx/resolver/native.rb', line 68

def closed?
  @state == :idle || @state == :closed
end

#consume ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 157

def consume
  loop do
    dread if calculate_interests == :r

    break unless calculate_interests == :w

    dwrite

    break unless calculate_interests == :r
  end
rescue Errno::EHOSTUNREACH => e
  @ns_index += 1
  nameserver = @nameserver
  if nameserver && @ns_index < nameserver.size
    log { "resolver #{FAMILY_TYPES[@record_type]}: failed resolving on nameserver #{@nameserver[@ns_index - 1]} (#{e.message})" }
    transition(:idle)
    @timeouts.clear
    retry
  else
    handle_error(e)
    disconnect
  end
rescue NativeResolveError => e
  handle_error(e)
  close_or_resolve
  retry unless closed?
end

#do_retry(h, connection, interval) ⇒ void

This method returns an undefined value.

Parameters:

  • host (String)
  • connection (Connection)
  • interval (interval) 


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# File 'lib/httpx/resolver/native.rb', line 204

def do_retry(h, connection, interval)
  timeouts = @timeouts[h]

  if !timeouts.empty?
    log { "resolver #{FAMILY_TYPES[@record_type]}: timeout after #{interval}s, retry (with #{timeouts.first}s) #{h}..." }
    # must downgrade to tcp AND retry on same host as last
    downgrade_socket
    resolve(connection, h)
  elsif @ns_index + 1 < @nameserver.size
    # try on the next nameserver
    @ns_index += 1
    log do
      "resolver #{FAMILY_TYPES[@record_type]}: failed resolving #{h} on nameserver #{@nameserver[@ns_index - 1]} (timeout error)"
    end
    transition(:idle)
    @timeouts.clear
    resolve(connection, h)
  else
    reset_hostname(h, reset_candidates: false)

    unless @queries.empty?
      resolve(connection)
      return
    end

    @connections.delete(connection)

    host = connection.peer.host

    # This loop_time passed to the exception is bogus. Ideally we would pass the total
    # resolve timeout, including from the previous retries.
    ex = ResolveTimeoutError.new(interval, "Timed out while resolving #{host}")
    ex.set_backtrace(ex ? ex.backtrace : caller)
    emit_resolve_error(connection, host, ex)

    close_or_resolve
  end
end

#downgrade_socket ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 514

def downgrade_socket
  return unless @socket_type == :tcp

  @socket_type = @resolver_options.fetch(:socket_type, :udp)
  transition(:idle)
  transition(:open)
end

#dread(arg0) ⇒ void #dread ⇒ void

Overloads:

  • #dread(arg0) ⇒ void

    This method returns an undefined value.

    Parameters:

    • arg0 (Integer)
  • #dread ⇒ void

    This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 243

def dread(wsize = @resolver_options[:packet_size])
  loop do
    wsize = @large_packet.capacity if @large_packet

    siz = @io.read(wsize, @read_buffer)

    unless siz
      ex = EOFError.new("descriptor closed")
      ex.set_backtrace(caller)
      raise ex
    end

    return unless siz.positive?

    if @socket_type == :tcp
      # packet may be incomplete, need to keep draining from the socket
      if @large_packet
        # large packet buffer already exists, continue pumping
        @large_packet << @read_buffer

        next unless @large_packet.full?

        parse(@large_packet.to_s)
        @large_packet = nil
        # downgrade to udp again
        downgrade_socket
        return
      else
        size = @read_buffer[0, 2].unpack1("n")
        buffer = @read_buffer.byteslice(2..-1)

        if size > @read_buffer.bytesize
          # only do buffer logic if it's worth it, and the whole packet isn't here already
          @large_packet = Buffer.new(size)
          @large_packet << buffer

          next
        else
          parse(buffer)
        end
      end
    else # udp
      parse(@read_buffer)
    end

    return if @state == :closed || !@write_buffer.empty?
  end
end

#dwrite ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 292

def dwrite
  loop do
    return if @write_buffer.empty?

    siz = @io.write(@write_buffer)

    unless siz
      ex = EOFError.new("descriptor closed")
      ex.set_backtrace(caller)
      raise ex
    end

    return unless siz.positive?

    schedule_retry if @write_buffer.empty?

    return if @state == :closed
  end
end

#force_close ⇒ Object 



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# File 'lib/httpx/resolver/native.rb', line 53

def force_close(*)
  @timer.cancel if @timer
  @timer = @name = nil
  @queries.clear
  @timeouts.clear
  close
  super
ensure
  terminate
end

#generate_candidates(name) ⇒ Array[String]

Parameters:

  • (String)

Returns:

  • (Array[String]) 


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# File 'lib/httpx/resolver/native.rb', line 485

def generate_candidates(name)
  return [name] if name.end_with?(".")

  name_parts = name.scan(/[^.]+/)
  candidates = @search.map { |domain| [*name_parts, *domain].join(".") }
  fname = "#{name}."
  if @ndots <= name_parts.size - 1
    candidates.unshift(fname)
  else
    candidates << fname
  end
  candidates
end

#handle_error(error) ⇒ Object 



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# File 'lib/httpx/resolver/native.rb', line 130

def handle_error(error)
  if error.respond_to?(:connection) &&
     error.respond_to?(:host)
    reset_hostname(error.host, connection: error.connection)
  else
    @queries.each do |host, connection|
      reset_hostname(host, connection: connection)
    end
  end

  super
end

#handle_socket_timeout(interval) ⇒ void

This method returns an undefined value.

Parameters:

  • interval (interval) 


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# File 'lib/httpx/resolver/native.rb', line 128

def handle_socket_timeout(interval); end

#interests ⇒ :r, ...

Returns:

  • (:r, :w, nil) 


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# File 'lib/httpx/resolver/native.rb', line 90

def interests
  case @state
  when :idle
    transition(:open)
  when :closed
    transition(:idle)
    transition(:open)
  end

  calculate_interests
end

#on_io_error ⇒ void

This method returns an undefined value.

Parameters:

  • error (IOError) 


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# File 'sig/resolver/native.rbs', line 40

def on_io_error: (IOError error) -> void

#parse(buffer) ⇒ void

This method returns an undefined value.

Parameters:

  • (String) 


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# File 'lib/httpx/resolver/native.rb', line 312

def parse(buffer)
  code, result = Resolver.decode_dns_answer(buffer)

  case code
  when :ok
    reset_query
    parse_addresses(result)
  when :no_domain_found
    reset_query
    # Indicates no such domain was found.
    hostname, connection = @queries.first
    reset_hostname(hostname, reset_candidates: false)

    other_candidate, _ = @queries.find { |_, conn| conn == connection }

    if other_candidate
      resolve(connection, other_candidate)
    else
      @connections.delete(connection)
      ex = NativeResolveError.new(connection, connection.peer.host, "name or service not known")
      ex.set_backtrace(ex ? ex.backtrace : caller)
      emit_resolve_error(connection, connection.peer.host, ex)
      close_or_resolve
    end
  when :message_truncated
    reset_query
    # TODO: what to do if it's already tcp??
    return if @socket_type == :tcp

    @socket_type = :tcp

    hostname, _ = @queries.first
    reset_hostname(hostname)
    transition(:closed)
  when :retriable_error
    if @name && @timer
      log { "resolver #{FAMILY_TYPES[@record_type]}: failed, but will retry..." }
      return
    end
    # retry now!
    # connection = @queries[@name].shift
    # @timer.fire
    reset_query
    hostname, connection = @queries.first
    reset_hostname(hostname)
    @connections.delete(connection)
    ex = NativeResolveError.new(connection, connection.peer.host, "unknown DNS error (error code #{result})")
    raise ex
  when :dns_error
    reset_query
    hostname, connection = @queries.first
    reset_hostname(hostname)
    @connections.delete(connection)
    ex = NativeResolveError.new(connection, connection.peer.host, "unknown DNS error (error code #{result})")
    raise ex
  when :decode_error
    reset_query
    hostname, connection = @queries.first
    reset_hostname(hostname)
    @connections.delete(connection)
    ex = NativeResolveError.new(connection, connection.peer.host, result.message)
    ex.set_backtrace(result.backtrace)
    raise ex
  end
end

#reset_hostname(hostname, connection: @queries.delete(hostname), reset_candidates: true) ⇒ void

This method returns an undefined value.

Parameters:

  • hostname (String)
  • connection: (Connection) (defaults to: @queries.delete(hostname))
  • reset_candidates: (Boolean) (defaults to: true) 


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# File 'lib/httpx/resolver/native.rb', line 576

def reset_hostname(hostname, connection: @queries.delete(hostname), reset_candidates: true)
  @timeouts.delete(hostname)

  return unless connection && reset_candidates

  # eliminate other candidates
  candidates = @queries.select { |_, conn| connection == conn }.keys
  @queries.delete_if { |h, _| candidates.include?(h) }
  # reset timeouts
  @timeouts.delete_if { |h, _| candidates.include?(h) }
end

#reset_query ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 570

def reset_query
  @timer.cancel

  @timer = @name = nil
end

#schedule_retry ⇒ void

This method returns an undefined value.



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# File 'lib/httpx/resolver/native.rb', line 185

def schedule_retry
  h = @name

  return unless h

  connection = @queries[h]

  timeouts = @timeouts[h]
  timeout = timeouts.shift

  @timer = @current_selector.after(timeout) do
    next unless @connections.include?(connection)

    @timer = @name = nil

    do_retry(h, connection, timeout)
  end
end

#terminate ⇒ Object 



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# File 'lib/httpx/resolver/native.rb', line 64

def terminate
  disconnect
end

#timeout ⇒ interval?

Returns:

  • (interval, nil) 


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# File 'lib/httpx/resolver/native.rb', line 114

def timeout
  return unless @name

  @start_timeout = Utils.now

  timeouts = @timeouts[@name]

  return if timeouts.empty?

  log(level: 2) { "resolver #{FAMILY_TYPES[@record_type]}: next timeout #{timeouts.first} secs... (#{timeouts.size - 1} left)" }

  timeouts.first
end

#to_io ⇒ Object 



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# File 'lib/httpx/resolver/native.rb', line 72

def to_io
  @io.to_io
end

#transition(nextstate) ⇒ void

This method returns an undefined value.

moves the resolver state machine to the nextstate state (if all conditions are met)-

Parameters:

  • nextstate (Symbol) 


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# File 'lib/httpx/resolver/native.rb', line 523

def transition(nextstate)
  case nextstate
  when :idle
    if (io = @io)
      @io = nil
      io.close

      # @fiber-switch-guard
      return if @io
    end
  when :open
    return unless @state == :idle

    @io ||= build_socket

    @io.connect
    return unless @io.connected?

    resolve if @queries.empty? && !@connections.empty?
  when :closed
    return if @state == :closed

    if (io = @io)
      @io = nil
      io.close

      # @fiber-switch-guard
      return if @io
    end

    @start_timeout = nil
    @write_buffer.clear
    @read_buffer.clear
  end
  log(level: 3) { "#{@state} -> #{nextstate}" }
  @state = nextstate
rescue Errno::ECONNREFUSED,
       Errno::EADDRNOTAVAIL,
       Errno::EHOSTUNREACH,
       SocketError,
       IOError,
       ConnectTimeoutError => e
  # these errors may happen during TCP handshake
  # treat them as resolve errors.
  on_error(e)
end