class Net::Ping::ICMP

The Net::Ping::ICMP class encapsulates an icmp ping.

Constants

ICMP_ECHO
ICMP_ECHOREPLY
ICMP_SUBCODE

Attributes

data_size[R]

Returns the data size, i.e. number of bytes sent on the ping. The default size is 56.

Public Instance Methods

bind(host, port = 0) click to toggle source

Associates the local end of the socket connection with the given host and port. The default port is 0.

# File lib/net/ping/icmp.rb, line 54
def bind(host, port = 0)
   @bind_host = host
   @bind_port = port
end
data_size=(size) click to toggle source

Sets the number of bytes sent in the ping method.

# File lib/net/ping/icmp.rb, line 45
def data_size=(size)
   @data_size = size
   @data = ''
   0.upto(size){ |n| @data << (n % 256).chr }
end
ping(host = @host) click to toggle source

Pings the host specified in this method or in the constructor. If a host was not specified either here or in the constructor, an ArgumentError is raised.

# File lib/net/ping/icmp.rb, line 63
def ping(host = @host)
   super(host)
   bool = false

   socket = Socket.new(
      Socket::PF_INET,
      Socket::SOCK_RAW,
      Socket::IPPROTO_ICMP
   )

   if @bind_host
      saddr = Socket.pack_sockaddr_in(@bind_port, @bind_host)
      socket.bind(saddr)
   end
   
   @seq = (@seq + 1) % 65536
   pstring = 'C2 n3 A' << @data_size.to_s
   timeout = @timeout

   checksum = 0
   msg = [ICMP_ECHO, ICMP_SUBCODE, checksum, @pid, @seq, @data].pack(pstring)
   checksum = checksum(msg)
   msg = [ICMP_ECHO, ICMP_SUBCODE, checksum, @pid, @seq, @data].pack(pstring)

   begin
      saddr = Socket.pack_sockaddr_in(0, host)
   rescue Exception
      socket.close unless socket.closed?
           return bool
   end
   
   start_time = Time.now

   socket.send(msg, 0, saddr) # Send the message

   begin
      Timeout.timeout(@timeout){
        while true
           io_array = select([socket], nil, nil, timeout)

           if io_array.nil? || io_array[0].empty?
              return false
           end

           pid = nil
           seq = nil

           data, sender  = socket.recvfrom(1500)
           port, host    = Socket.unpack_sockaddr_in(sender)
           type, subcode = data[20, 2].unpack('C2')

           case type
              when ICMP_ECHOREPLY
                 if data.length >= 28
                    pid, seq = data[24, 4].unpack('n3')
                 end
              else
                 if data.length > 56
                    pid, seq = data[52, 4].unpack('n3')
                 end
           end

           if pid == @pid && seq == @seq && type == ICMP_ECHOREPLY
              bool = true
              break
           end
        end
      }
   rescue Exception => err
      @exception = err
   ensure
      socket.close if socket
   end
   
   # There is no duration if the ping failed
   @duration = Time.now - start_time if bool

   return bool
end
Also aliased as: ping?, pingecho
ping?(host = @host) click to toggle source
Alias for: ping
pingecho(host = @host) click to toggle source
Alias for: ping

Public Class Methods

new(host=nil, port=nil, timeout=5) click to toggle source

Creates and returns a new Ping::ICMP object. This is similar to its superclass constructor, but must be created with root privileges (on UNIX systems), and the port value is ignored.

# File lib/net/ping/icmp.rb, line 26
def initialize(host=nil, port=nil, timeout=5)
   raise 'requires root privileges' if Process.euid > 0

   @seq = 0
   @bind_port = 0
   @bind_host = nil
   @data_size = 56
   @data = ''

   0.upto(@data_size){ |n| @data << (n % 256).chr }

   @pid  = Process.pid & 0xffff

   super(host, port, timeout)
   @port = nil # This value is not used in ICMP pings.
end