#!/usr/bin/env python

"""
    Original source: https://raw.githubusercontent.com/samuel/python-ping/master/ping.py
"""

import os, sys, socket, struct, select, time, string, random


class ICMP():
	ICMP_ECHO_REQUEST = 8
	def __init__(self):
		self.ident = os.getpid() & 0xFFFF
		icmp = socket.getprotobyname("icmp")
		try:
			self.icmp_sock = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
		except socket.error:
			if socket.errno == EACCES:
				# Operation not permitted
				msg = socket.strerror + (
					" - Note that ICMP messages can only be sent from processes"
					" running as root."
				)
				raise socket.error(msg)
			raise # raise the original error

	def __del__(self):
		self.icmp_sock.close()
		del self.icmp_sock, self.ident

	def checksum(self, source_string):
		sum = 0
		countTo = (len(source_string)/2)*2
		count = 0
		while count<countTo:
			thisVal = ord(source_string[count + 1])*256 + ord(source_string[count])
			sum = sum + thisVal
			sum = sum & 0xffffffff # Necessary?
			count = count + 2

		if countTo<len(source_string):
			sum = sum + ord(source_string[len(source_string) - 1])
			sum = sum & 0xffffffff # Necessary?

		sum = (sum >> 16)  +  (sum & 0xffff)
		sum = sum + (sum >> 16)
		answer = ~sum
		answer = answer & 0xffff

		# Swap bytes. Bugger me if I know why.
		answer = answer >> 8 | (answer << 8 & 0xff00)

		return answer

	def receive_one_ping(self, ID, timeout):
		timeLeft = timeout
		while True:
			startedSelect = time.time()
			whatReady = select.select([self.icmp_sock], [], [], timeLeft)
			howLongInSelect = (time.time() - startedSelect)
			if whatReady[0] == []: # Timeout
				return

			timeReceived = time.time()
			recPacket, addr = self.icmp_sock.recvfrom(1024)
			icmpHeader = recPacket[20:28]
			type, code, checksum, packetID, sequence = struct.unpack("bbHHh", icmpHeader)
			# Filters out the echo request itself. 
			# This can be tested by pinging 127.0.0.1 
			# You'll see your own request
			if type != 8 and packetID == ID:
				bytesInDouble = struct.calcsize("d")
				timeSent = struct.unpack("d", recPacket[28:28 + bytesInDouble])[0]
				return timeReceived - timeSent

			timeLeft = timeLeft - howLongInSelect
			if timeLeft <= 0:
				return

	def send_one_ping(self, dest_addr, ID):
		"""
		Send one ping to the given >dest_addr<.
		"""
		dest_addr  =  socket.gethostbyname(dest_addr)
		# Header is type (8), code (8), checksum (16), id (16), sequence (16)
		my_checksum = 0
		# Make a dummy heder with a 0 checksum.
		header = struct.pack("bbHHh", self.ICMP_ECHO_REQUEST, 0, my_checksum, ID, 1)
		bytesInDouble = struct.calcsize("d")
		data = (192 - bytesInDouble) * random.choice(string.letters)
		data = struct.pack("d", time.time()) + data
		# Calculate the checksum on the data and the dummy header.
		my_checksum = self.checksum(header + data)
		# Now that we have the right checksum, we put that in. It's just easier
		# to make up a new header than to stuff it into the dummy.
		header = struct.pack("bbHHh", self.ICMP_ECHO_REQUEST, 0, socket.htons(my_checksum), ID, 1)
		packet = header + data
		self.icmp_sock.sendto(packet, (dest_addr, 1)) # Don't know about the 1
	
	def do_one(self, dest_addr, timeout):
		"""
		Returns either the delay (in seconds) or none on timeout.
		"""
		self.send_one_ping(dest_addr, self.ident)
		delay = self.receive_one_ping(self.ident, timeout)
		return delay

	def verbose_ping(self, dest_addr, timeout = 2, count = 4):
		"""
		Send >count< ping to >dest_addr< with the given >timeout< and display
		the result.
		"""
		for i in xrange(count):
			print('ping %s...' % dest_addr,)
			try:
				delay  =  self.do_one(dest_addr, timeout)
			except socket.gaierror as e:
				print('failed. (socket error: "%s")' % e[1])
				break

			if delay  ==  None:
				print('failed. (timeout within %ssec.)' % timeout)
			else:
				delay  =  delay * 1000
				print('get ping in %0.4fms' % delay)
		print


if __name__ == '__main__':
	icmp = ICMP()
	icmp.verbose_ping("heise.de")
	icmp.verbose_ping("google.com")
	icmp.verbose_ping("a-test-url-taht-is-not-available.com")
	icmp.verbose_ping("192.168.1.1")
	del icmp