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#
# ping.rb -- check a host for upness
#
#= SYNOPSIS
#
# require 'ping'
# print "'jimmy' is alive and kicking\n" if Ping.pingecho('jimmy', 10) ;
#
#= DESCRIPTION
#
# This module contains routines to test for the reachability of remote hosts.
# Currently the only routine implemented is pingecho().
#
# pingecho() uses a TCP echo (I<not> an ICMP one) to determine if the
# remote host is reachable. This is usually adequate to tell that a remote
# host is available to rsh(1), ftp(1), or telnet(1) onto.
#
#== Parameters
#
# : hostname
#
# The remote host to check, specified either as a hostname or as an
# IP address.
#
# : timeout
#
# The timeout in seconds. If not specified it will default to 5 seconds.
#
# : service
#
# The service port to connect. The default is "echo".
#
#= WARNING
#
# pingecho() uses user-level thread to implement the timeout, so it may block
# for long period if named does not respond for some reason.
#
#=end
require 'timeout'
require "socket"
module Ping
def pingecho(host, timeout=5, service="echo")
begin
timeout(timeout) do
s = TCPSocket.new(host, service)
s.close
end
rescue Errno::ECONNREFUSED
return true
rescue Timeout::Error, StandardError
return false
end
return true
end
module_function :pingecho
end
if $0 == __FILE__
host = ARGV[0]
host ||= "localhost"
printf("%s alive? - %s\n", host, Ping::pingecho(host, 5))
end
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