module Net::SSH::Transport::PacketStream

def self.extended(object)
  object.__send__(:initialize_ssh)
end

def available_for_read?
  result = Net::SSH::Compat.io_select([self], nil, nil, 0)
  result && result.first.any?
end

def cleanup
  client.cleanup
  server.cleanup
end

def client_name
  @client_name ||= begin
    sockaddr = getsockname
    begin
      Socket.getnameinfo(sockaddr, Socket::NI_NAMEREQD).first
    rescue
      begin
        Socket.getnameinfo(sockaddr).first
      rescue
        begin
          Socket.gethostbyname(Socket.gethostname).first
        rescue
          lwarn { "the client ipaddr/name could not be determined" }
          "unknown"
        end
      end
    end
  end
end

def enqueue_packet(payload)
  # try to compress the packet
  payload = client.compress(payload)
  # the length of the packet, minus the padding
  actual_length = 4 + payload.bytesize + 1
  # compute the padding length
  padding_length = client.block_size - (actual_length % client.block_size)
  padding_length += client.block_size if padding_length < 4
  # compute the packet length (sans the length field itself)
  packet_length = payload.bytesize + padding_length + 1
  if packet_length < 16
    padding_length += client.block_size
    packet_length = payload.bytesize + padding_length + 1
  end
  padding = Array.new(padding_length) { rand(256) }.pack("C*")
  unencrypted_data = [packet_length, padding_length, payload, padding].pack("NCA*A*")
  mac = client.hmac.digest([client.sequence_number, unencrypted_data].pack("NA*"))
  encrypted_data = client.update_cipher(unencrypted_data) << client.final_cipher
  message = encrypted_data + mac
  debug { "queueing packet nr #{client.sequence_number} type #{payload.getbyte(0)} len #{packet_length}" }
  enqueue(message)
  client.increment(packet_length)
  self
end

def if_needs_rekey?
  if client.needs_rekey? || server.needs_rekey?
    yield
    client.reset! if client.needs_rekey?
    server.reset! if server.needs_rekey?
  end
end

def initialize_ssh
  @hints  = {}
  @server = State.new(self, :server)
  @client = State.new(self, :client)
  @packet = nil
  initialize_buffered_io
end

def next_packet(mode=:nonblock)
  case mode
  when :nonblock then
    if available_for_read?
      if fill <= 0
        raise Net::SSH::Disconnect, "connection closed by remote host"
      end
    end
    poll_next_packet
  when :block then
    loop do
      packet = poll_next_packet
      return packet if packet
      loop do
        result = Net::SSH::Compat.io_select([self]) or next
        break if result.first.any?
      end
      if fill <= 0
        raise Net::SSH::Disconnect, "connection closed by remote host"
      end
    end
  else
    raise ArgumentError, "expected :block or :nonblock, got #{mode.inspect}"
  end
end

def peer_ip
  @peer_ip ||=
    if respond_to?(:getpeername)
      addr = getpeername
      Socket.getnameinfo(addr, Socket::NI_NUMERICHOST | Socket::NI_NUMERICSERV).first
    else
      "<no hostip for proxy command>"
    end
end

def poll_next_packet
  if @packet.nil?
    minimum = server.block_size < 4 ? 4 : server.block_size
    return nil if available < minimum
    data = read_available(minimum)
    # decipher it
    @packet = Net::SSH::Buffer.new(server.update_cipher(data))
    @packet_length = @packet.read_long
  end
  need = @packet_length + 4 - server.block_size
  raise Net::SSH::Exception, "padding error, need #{need} block #{server.block_size}" if need % server.block_size != 0
  return nil if available < need + server.hmac.mac_length
  if need > 0
    # read the remainder of the packet and decrypt it.
    data = read_available(need)
    @packet.append(server.update_cipher(data))
  end
  # get the hmac from the tail of the packet (if one exists), and
  # then validate it.
  real_hmac = read_available(server.hmac.mac_length) || ""
  @packet.append(server.final_cipher)
  padding_length = @packet.read_byte
  payload = @packet.read(@packet_length - padding_length - 1)
  my_computed_hmac = server.hmac.digest([server.sequence_number, @packet.content].pack("NA*"))
  raise Net::SSH::Exception, "corrupted mac detected" if real_hmac != my_computed_hmac
  # try to decompress the payload, in case compression is active
  payload = server.decompress(payload)
  debug { "received packet nr #{server.sequence_number} type #{payload.getbyte(0)} len #{@packet_length}" }
  server.increment(@packet_length)
  @packet = nil
  return Packet.new(payload)
end

def send_packet(payload)
  enqueue_packet(payload)
  wait_for_pending_sends
end