class Net::SSH::Transport::Session

def poll_message(mode = :nonblock, consume_queue = true)

read from the queue before the socket is queried.
is not in process, and consume_queue is true, packets will be first
received, it will be enqueued and otherwise ignored. When a key-exchange
If a key-exchange is in process and a disallowed packet type is

be returned.
DEBUG, and KEXINIT) are handled silently by this method, and will never
available. Note that some packet types (DISCONNECT, IGNORE, UNIMPLEMENTED,
waiting to be read. Otherwise, this will block until a packet is
default), this will not block and will return nil if there are no packets
Tries to read the next packet from the socket. If mode is :nonblock (the 
def poll_message(mode = :nonblock, consume_queue = true)
  loop do
    return @queue.shift if consume_queue && @queue.any? && algorithms.allow?(@queue.first)
    packet = socket.next_packet(mode, options[:timeout])
    return nil if packet.nil?
    case packet.type
    when DISCONNECT
      raise Net::SSH::Disconnect, "disconnected: #{packet[:description]} (#{packet[:reason_code]})"
    when IGNORE
      debug { "IGNORE packet received: #{packet[:data].inspect}" }
    when UNIMPLEMENTED
      lwarn { "UNIMPLEMENTED: #{packet[:number]}" }
    when DEBUG
      send(packet[:always_display] ? :fatal : :debug) { packet[:message] }
    when KEXINIT
      algorithms.accept_kexinit(packet)
    else
      return packet if algorithms.allow?(packet)
      push(packet)
    end
  end
end