From: Daniel Berger <djberge@...55host11.interprise.com>
Date: 2002-08-17T02:18:14+09:00
Subject: RFC: Net/Ping

Hi all,

This is a fairly simple Ruby version of 'ping', based somewhat on the Perl module of the same name.  
Please let me know what you think and if there are any obvious problems.

I haven't implemented an ICMP ping yet, mainly because it's a pain and you have to be root to use it 
anyway.  Any help in that area is appreciated, though.

Oh, and before anyone complains about a lack of options, see "Unix Network Programming", p.661 and note 
the authors comments about "feature creep". :)

Regards,

Dan

require "socket"
require "timeout"

module Net
   class Ping
      attr_accessor :host, :port, :time, :data, :exception
      def initialize(host,port=nil,time=5)
         @host = host
         @port = port || Socket.getservbyname("echo")
         @time = time
         @data = "ping"
      end
   end

   ##########################################################################
   # With a TCP ping, simply try to open a connection.  If we are successful,
   # assume success.  In either case, close the connection to be polite.
   ##########################################################################
   class PingTCP < Ping
      def ping
         begin
            timeout(@time){
               begin
                  t = TCPSocket.new(@host,@port)
               rescue
                  @exception = $!
                  t.close unless t.nil?
                  return false
               else
                  t.close
                  return true
               end
            }
         rescue
            @exception = $!
            return false
         end
      end
   end 

   ##########################################################################
   # With a UDP ping, send a simple text string and check the return string.
   # If they match, assume success.
   ##########################################################################
   class PingUDP < Ping

      def ping
         u = UDPSocket.open
         a = []
         begin
            timeout(@time){
               u.connect(@host,@port)
               u.send(@data,0)
               a = u.recvfrom(64)
            }
            if a[0] != @data
               return false
            end
         rescue
            @exception = $!
            return false
         else
            return true
         end
      end
   end

   ##################################
   # Use your system's ping command
   ##################################
   class PingExternal < Ping
      require "open3"
      def ping
         input, output, error = ""
         timeout(@timeout){
            input,output,error = Open3.popen3("ping -c 1 #{@host}")
         }
         e = error.gets
         unless e.nil?
            @exception = e
            return false
         else
            return true
         end    
      end
   end

end

=begin
= Description
   net/ping - A simple version of "ping" using Ruby
= Synopsis
   require 'net/ping'

   # check with udp or tcp ping

   t = Net::PingTCP.new(host)
   u = Net::PingUDP.new(host)
   e = Net::PingExternal.new(host)

   if t.ping
      puts "Host is alive"
   else
      puts "Couldn't connect to host: " + t.exception
   end
= Ping Classes
--- PingTCP
   Attempts to open a connection using TCPSocket.  A successful open means
   the ping was successful.
--- PingUDP
   Attempts to open a connection using UDPSocket and sends a small string.  If
   the return string matches, the ping was successful.
--- PingExternal
   Uses the 'open3' module and calls your system's local 'ping' command.  If
   nothing is sent to stderr, the ping was successful.
= Class Methods
--- new(host,port=7,timeout=5)
   Creates a new Ping object of the appropriate type 
= Instance Methods
--- ping
   Returns one of two values - true or false.  If you want to know *why* it
   failed, you can check the 'exception' attribute.
= Instance Attributes
--- host
   Reset the host
--- port
   Set the port number to open socket connections on.  The default is 7 (or
   whatever your 'echo' port is set to).
--- data
   The string sent in UDP connections.  The default is "ping".
--- timeout
   The amount of time before the timeout module raises a TimeoutError
   exception during connection attempts.
--- exception
   If an exception is raised, it is caught and stored in this attribute.  It
   is not raised in your code.
= FAQ
   "Why don't you return exceptions if a connection fails?" - Because ping is
   only meant to return one of two things - success or failure.  It's very
   simple.  If you want to find out *why* the ping failed, you can check the
   'exception' attribute.
= Known Bugs
   None that I'm aware of.  If you find any, please let me know!
= Future Plans
   Add an PingICMP class (help wanted)
= Author
   Daniel J. Berger
   djberg96 at hotmail dot com
=end