require 'socket'

class IO
	def connected?
		!closed?
	end
end

class Socket
	def connected?
		# Is it likely that the socket is still connected?
		# May return false positive, but won't return false negative.
		return false unless super
		
		# If we can wait for the socket to become readable, we know that the socket may still be open.
		result = to_io.recv_nonblock(1, MSG_PEEK, exception: false)
		
		# No data was available - newer Ruby can return nil instead of empty string:
		return false if result.nil?
		
		# Either there was some data available, or we can wait to see if there is data avaialble.
		return !result.empty? || result == :wait_readable
	rescue Errno::ECONNRESET
		# This might be thrown by recv_nonblock.
		return false
	end
end