Class: StunClient::RFC3489NATDiscovery

Inherits:
Object
  • Object
show all
Defined in:
lib/stun-client/rfc3489/discovery/nat.rb

Overview

Helper, which should determine the NAT type.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(host = nil, port = nil, protocol = :IPv4) ⇒ RFC3489NATDiscovery

Creates a new object for NAT discovery.

Parameters:

  • host (String) (defaults to: nil) —

    The host of the STUN server to be used for NAT discovery. By default, the default server of the STUN client is used.

  • port (Integer) (defaults to: nil) —

    The port of the STUN server.

  • protocol (Symbol) (defaults to: :IPv4) —

    Defines whether the STUN server should be reached via IPv4 or IPv6. Accordingly like a NATv4 or NATv6 detected. Possible values are ‘:IPv4` or `:IPv6`.

Raises:

  • (ArgumentError) 


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# File 'lib/stun-client/rfc3489/discovery/nat.rb', line 27

def initialize host = nil, port = nil, protocol = :IPv4
  raise ArgumentError, 'Host must be a string' if host && (! host.is_a? String)
  raise ArgumentError, 'Port must be a integer' if port && (! port.is_a? Integer)

  case protocol
  when :IPv6
    inet = Socket::AF_INET6
    addr = '::'
  when :IPv4
    inet = Socket::AF_INET
    addr = '0.0.0.0'
  else
    raise ArgumentError, 'Unknown protocol'
  end

  @host = host
  @port = port

  @socket = UDPSocket.new inet
  @socket.do_not_reverse_lookup = true
  @socket.bind addr, 0
  @source_port = @socket.addr[1]
end

Class Method Details

.get_local_addresses ⇒ Array

Returns an array with the IP addresses of the local device. rubocop:disable Naming/AccessorMethodName

Returns:

  • (Array) 


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# File 'lib/stun-client/rfc3489/discovery/nat.rb', line 12

def self.get_local_addresses
  return Socket.ip_address_list.map(&:ip_address)
end

Instance Method Details

#detect_nat ⇒ Array

Checks the NAT Type and returns an array with a corresponding description. In the worst case, it can take up to 38 seconds for the function to finish.

Important: Keep in mind that RFC3489 is outdated and that measurements are not always accurate.

Returns:

  • (Array) —

    :preserves_ports The local ports are mapped to the outside. Example: If a socket is created locally with port 4000, this is also the source port when a server is requested. :random_port The opposite of ‘:preserves_ports`.

    :nat The device is located behind a NAT. :no_nat The device is not located behind a NAT.

    :open_internet The device is openly located on the Internet. No filtering is performed. :symmetric_udp_firewall The device is located behind a firewall that filters by source port and source address.

    :full_cone_nat The device is located behind a Full Cone NAT. The NAT does not filter the source port or source address. :restricted_nat The device is behind a restrictive NAT. The NAT filters only by source address, but not by source port. :port_restricted_nat The device is located behind a port-restricted NAT. The NAT filters by source port and source address.

    :udp_blocked The STUN server could not be reached. Therefore, the measurement could not be executed. :udp_sometimes_blocked This case should never leak. It means that an inconsistent NAT/firewall is used. One of the requests to the STUN server was blocked. Therefore, the measurement could not be completed.



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# File 'lib/stun-client/rfc3489/discovery/nat.rb', line 84

def detect_nat
  # rubocop:disable Style/ConditionalAssignment
  flags = []

  test1v1 = do_query @host, @port

  if test1v1
    if test1v1[:port] == @source_port
      flags << :preserves_ports
    else
      flags << :random_port
    end

    if RFC3489NATDiscovery.get_local_addresses.include?(test1v1[:host]) &&
       test1v1[:port] == @source_port

      flags << :no_nat

      test2 = do_query @host, @port, change_ip: true, change_port: true
      if test2
        flags << :open_internet
      else
        flags << :symmetric_udp_firewall
      end
    else
      flags << :nat

      test2 = do_query @host, @port, change_ip: true, change_port: true
      if test2
        flags << :full_cone_nat
      else
        test1v2 = do_query test1v1[:changed_host], test1v1[:changed_port].to_i
        if test1v2
          if test1v1[:host] == test1v2[:host] &&
             test1v1[:port] == test1v2[:port]
            test3 = do_query @host, @port, change_port: true
            if test3
              flags << :restricted_nat
            else
              flags << :port_restricted_nat
            end
          else
            flags << :symmetric_nat
          end
        else
          flags << :udp_sometimes_blocked
        end
      end
    end

  else
    flags << :udp_blocked
  end

  # flags.sort!
  return flags

  # rubocop:enable Style/ConditionalAssignment
end