Closing socket doesn't work in Ruby - ruby

Question

I am attempting to create a better port scanner by implementing more error handling, and I've run into a bit of trouble.
def pscan(host_name, port)
begin
sock = Socket.new(:INET, :STREAM)
raw = Socket.sockaddr_in(port, host_name)
if sock.connect(raw)
puts "Port #{port} is up!"
rescue (Errno::ECONNREFUSED)
false
rescue (Errno::ETIMEDOUT)
puts "Port #{port} timed out!"
end
end
def run
port = 1
begin
while port <= ARGV[1].to_i do
popen(ARGV[0], port)
port += 1
end
rescue (Errno::EHOSTUNREACH)
puts "No path to host"
rescue(Interrupt)
puts " Process interrupted"
end
end
run
The trouble is that for each port scanned, it will print "No path to host", instead of printing that once and then closing the socket. I'm clearly doing it wrong but everywhere online I find simple code closes a socket connection this way.

Answer 1

I think that you forgot to close the if statement. Also, use 'ensure' to close it.
Try this:
def pscan(host_name, port)
begin
sock = Socket.new(:INET, :STREAM)
raw = Socket.sockaddr_in(port, host_name)
if sock.connect(raw)
puts "Port #{port} is up!"
end
rescue (Errno::ECONNREFUSED)
false
rescue (Errno::ETIMEDOUT)
puts "Port #{port} timed out!"
rescue (Errno::EHOSTUNREACH)
puts "No path to host"
ensure
sock.close
end
end

Answer 2

Like you mentioned in your comments and your code changes, you would have to move the socket closing into the block that's calling your code rather than inside of that code itself, since the block of code will continuously call the method and the socket will never actually be closed.
You'll basically have to do what you posted in your code:
require 'socket'
def pscan(host_name, port)
begin
sock = Socket.new(:INET, :STREAM)
raw = Socket.sockaddr_in(port, host_name)
if sock.connect(raw)
puts "Port #{port} is up!"
end
rescue (Errno::ECONNREFUSED)
puts "Connection refused to port #{port}"
false
rescue (Errno::ETIMEDOUT)
puts "Port #{port} timed out!"
false
end
end
def run
puts "Attempting to scan host #{ARGV[0]}"
port = 1
begin
while port <= ARGV[1].to_i do
pscan(ARGV[0], port)
port += 1
end
rescue (Errno::EHOSTUNREACH)
puts "No path to host #{ARVG[0]}"
rescue(Interrupt)
puts "Process interrupted"
end
end
run
Some thoughts: you may not always get "No path to host" errors when running your code; when I tested it in my network, I never got a "No path to host" error but always got a "Port ... timed out!" error even when I tested it against known unreachable hosts such as 10.0.0.1. You'll have to be wary of that when you run your code in other networks as you might get different results.