class Net::SSH::Authentication::Methods::Hostbased

def authenticate(next_service, username, password = nil)
  return false unless key_manager
  key_manager.each_identity do |identity|
    return true if authenticate_with(identity, next_service,
                                     username, key_manager)
  end
  return false
end

def authenticate_with(identity, next_service, username, key_manager)
  debug { "trying hostbased (#{identity.fingerprint})" }
  client_username = ENV['USER'] || username
  req = build_request(identity, next_service, username, "#{hostname}.", client_username)
  sig_data = Buffer.from(:string, session_id, :raw, req)
  sig = key_manager.sign(identity, sig_data.to_s)
  message = Buffer.from(:raw, req, :string, sig)
  send_message(message)
  message = session.next_message
  case message.type
  when USERAUTH_SUCCESS
    info { "hostbased succeeded (#{identity.fingerprint})" }
    return true
  when USERAUTH_FAILURE
    info { "hostbased failed (#{identity.fingerprint})" }
    raise Net::SSH::Authentication::DisallowedMethod unless
      message[:authentications].split(/,/).include? 'hostbased'
    return false
  else
    raise Net::SSH::Exception, "unexpected server response to USERAUTH_REQUEST: #{message.type} (#{message.inspect})"
  end
end

def build_request(identity, next_service, username, hostname, client_username)
  userauth_request(username, next_service, "hostbased", identity.ssh_type,
                   Buffer.from(:key, identity).to_s, hostname, client_username).to_s
end

def hostname
  session.transport.socket.client_name
end