DZone Snippets: port code

Run TCPServer as a simple Web server

jrobertson (James Robertson) — Thu, 10 Apr 2008 14:05:56 GMT

A TCPServer accepts incoming TCP connections. Here is a Web server that listens on a given port and returns the time.



require 'socket'

port = (ARGV[0] || 80).to_i

server = TCPServer.new('localhost', port)

while (session = server.accept)

  puts "Request: #{session.gets}"

  session.print "HTTP/1.1 200/OK\r\nContent-type: text/html\r\n\r\n"

  session.print "#{Time.now}\r\n"

  session.close

end

This code was copied from Programming Ruby: The Pragmatic Programmer's Guide [rubycentral.com] while looking for information on Ruby CGI global variables.

Introduction to Distributed Ruby

jrobertson (James Robertson) — Sat, 15 Mar 2008 00:59:13 GMT

This code demonstrates a client server architecture. I executed the file simple_service.rb on my Ubuntu server (Donatello - 192.168.1.10), then from the CLI output I copied the server uri into the clipboard. I then executed the simple_client.rb on my Ubuntu desktop (Cryton - 192.168.1.3) while passing in the uri as an argument.



#!/usr/bin/env ruby -w

# simple_service.rb

# A simple DRb service



# load DRb

require 'drb'



# start up the DRb service

DRb.start_service nil, []



# We need the uri of the service to connect a client

puts DRb.uri



# wait for the DRb service to finish before exiting

DRb.thread.join

output: druby://donatello.mydomain.com:47159



#!/usr/bin/env ruby -w

# simple_client.rb

# A simple DRb client



require 'drb'



DRb.start_service



# attach to the DRb server via a URI given on the command line

remote_array = DRbObject.new nil, ARGV.shift



puts remote_array.size



remote_array << 1



puts remote_array.size

from the command line
> ./simple_client.rb druby://192.168.1.10:47159

output:
0
1

Note: I substituted the domain name with the ip address because the name in question was not stored within the DNS settings.

Reference: Introduction to Distributed Ruby (DRb) [segment7.net]

Send custom UDP packets in Ruby

ntk () — Fri, 14 Sep 2007 11:19:36 GMT

From: http://www.ruby-forum.com/topic/124159
Author: Bill Kelly

For yet another nifty UDP snippet see Skype-Style Firewall Busting with Ruby and UDP.





require 'socket'



#abort "Usage: server_addr, server_port, cmd_str" unless ARGV.length == 3



UDP_RECV_TIMEOUT = 3  # seconds



def q2cmd(server_addr, server_port, cmd_str)

  resp, sock = nil, nil

  begin

   cmd = "\377\377\377\377#{cmd_str}\0"

    sock = UDPSocket.open

    sock.send(cmd, 0, server_addr, server_port)

    resp = if select([sock], nil, nil, UDP_RECV_TIMEOUT)

      sock.recvfrom(65536)

    end

    if resp

      resp[0] = resp[0][4..-1]  # trim leading 0xffffffff

    end

  rescue IOError, SystemCallError

  ensure

    sock.close if sock

  end

  resp ? resp[0] : nil

end



# your firewall has to allow communication with IP address 67.19.248.74 (port 27912)

#server, port, cmd = *ARGV

server = "tastyspleen.net"

port = 27912

cmd = "status"



result = q2cmd(server, port, cmd)

puts result

J2ME - getIPdevice

whitetiger () — Wed, 28 Feb 2007 00:15:46 GMT

// Retrevie IP device



package org.socketdemo;



import javax.microedition.io.Connector;

import javax.microedition.io.SocketConnection;

import javax.microedition.lcdui.Alert;

import javax.microedition.lcdui.AlertType;

import javax.microedition.lcdui.Command;

import javax.microedition.lcdui.CommandListener;

import javax.microedition.lcdui.Display;

import javax.microedition.lcdui.Displayable;

import javax.microedition.midlet.MIDlet;

import javax.microedition.midlet.MIDletStateChangeException;



public class SocketDEMO extends MIDlet implements CommandListener

{

	protected SocketDEMO midlet = this;

	

	private Alert info;

	

	protected void destroyApp(boolean value) throws MIDletStateChangeException

	{

		notifyDestroyed();

	}



	protected void pauseApp()

	{



	}



	protected void startApp() throws MIDletStateChangeException

	{

		new Thread()

		{

			public void run()

			{

				SocketConnection socket = null;

				

				try

				{

					socket = (SocketConnection) Connector.open("socket://193.204.114.233:13");

					

					socket.openInputStream();

					

					info = new Alert("Info", "Current IP: " + socket.getLocalAddress() + "\nPort: " + socket.getLocalPort(), null, AlertType.INFO);

					info.setTimeout(Alert.FOREVER);

					info.setCommandListener(midlet);

					

					getDisplay().setCurrent(info);

				}

				catch(Exception error)

				{

					info = new Alert("Info", "Current IP: N/A\nPort: N/A", null, AlertType.INFO);

					info.setTimeout(Alert.FOREVER);

					info.setCommandListener(midlet);

					

					getDisplay().setCurrent(info);

				}

				finally

				{

					if(socket != null)

					{

						try

						{

							socket.close();

						}

						catch(Exception error)

						{

							

						}

					}

				}

			}

		}.start();

	}

	

	protected Display getDisplay()

	{

		return Display.getDisplay(this);

	}



	public void commandAction(Command cmd, Displayable dsp)

	{

		if(cmd == Alert.DISMISS_COMMAND)

		{

			try

			{

				destroyApp(true);

			}

			catch(MIDletStateChangeException error)

			{

			

			}

		}

	}

}

Apache2 proxy to local port

brainpipe () — Tue, 31 Jan 2006 11:09:16 GMT

Apache as the receptionist, forwarding requests to and from an internal server (e.g. webrick or lighttpd).





        ServerName www.example.com

        ProxyPass / http://localhost:3000/

        ProxyPassReverse / http://localhost:3000/

        ProxyPreserveHost On

Change 3000 to whatever port you need and make sure the internal server is set up to answer requests on that port (not port 80). The ProxyPreserveHost line is critical to keep all your URLs working correctly.