from socket import *
import os
import sys
import struct
import time
import select
import binascii  

ICMP_ECHO_REQUEST = 8

def checksum(str): 
	csum = 0
	countTo = (len(str) / 2) * 2
	
	count = 0
	while count < countTo:
		thisVal = ord(str[count+1]) * 256 + ord(str[count]) 
		csum = csum + thisVal 
		csum = csum & 0xffffffffL  
		count = count + 2
	
	if countTo < len(str):
		csum = csum + ord(str[len(str) - 1])
		csum = csum & 0xffffffffL
	
	csum = (csum >> 16) + (csum & 0xffff)
	csum = csum + (csum >> 16)
	answer = ~csum 
	answer = answer & 0xffff 
	answer = answer >> 8 | (answer << 8 & 0xff00)
	return answer 
	
def receiveOnePing(mySocket, ID, timeout, destAddr):
	timeLeft = timeout
	
	while 1: 
		startedSelect = time.time()
		whatReady = select.select([mySocket], [], [], timeLeft)
		howLongInSelect = (time.time() - startedSelect)
		if whatReady[0] == []: # Timeout
			return "Request timed out."
	
		timeReceived = time.time() 
		recPacket, addr = mySocket.recvfrom(1024)
		
		# Fetch the ICMPHeader fromt the IP
		icmpHeader = recPacket[20:28]
		rawTTL = struct.unpack("s", recPacket[8])[0]  
		# binascii -- Convert between binary and ASCII  
		TTL = int(binascii.hexlify(str(rawTTL)), 16)
		
		icmpType, code, checksum, packetID, sequence = struct.unpack("bbHHh", icmpHeader)
		
		if packetID == ID:
			bytes = struct.calcsize("d") 
			timeSent = struct.unpack("d", recPacket[28:28 + bytes])[0]
			return "Reply from %s: bytes=%d time=%f5ms TTL=%d" % (destAddr, len(recPacket), (timeReceived - timeSent)*1000, TTL)
		
		timeLeft = timeLeft - howLongInSelect
		if timeLeft <= 0:
			return "Request timed out."
	
def sendOnePing(mySocket, destAddr, ID):
	# Header is type (8), code (8), checksum (16), id (16), sequence (16)
	
	myChecksum = 0
	# Make a dummy header with a 0 checksum
	# struct -- Interpret strings as packed binary data
	header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1)
	data = struct.pack("d", time.time())
	# Calculate the checksum on the data and the dummy header.
	myChecksum = checksum(header + data)
	
	# Get the right checksum, and put in the header
	if sys.platform == 'darwin':
		# Convert 16-bit integers from host to network  byte order
		myChecksum = htons(myChecksum) & 0xffff		
	else:
		myChecksum = htons(myChecksum)
		
	header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1)
	packet = header + data
	
	mySocket.sendto(packet, (destAddr, 1)) # AF_INET address must be tuple, not str
	# Both LISTS and TUPLES consist of a number of objects
	# which can be referenced by their position number within the object.
	
def doOnePing(destAddr, timeout): 
	icmp = getprotobyname("icmp")
	# SOCK_RAW is a powerful socket type. For more details:   http://sock-raw.org/papers/sock_raw

	mySocket = socket(AF_INET, SOCK_RAW, icmp)
	
	myID = os.getpid() & 0xFFFF  # Return the current process i
	sendOnePing(mySocket, destAddr, myID)
	delay = receiveOnePing(mySocket, myID, timeout, destAddr)
	
	mySocket.close()
	return delay
	
def ping(host, timeout=1):
	# timeout=1 means: If one second goes by without a reply from the server,
	# the client assumes that either the client's ping or the server's pong is lost
	dest = gethostbyname(host)
	print "Pinging " + dest + " using Python:"
	print ""
	# Send ping requests to a server separated by approximately one second
	while 1 :
		delay = doOnePing(dest, timeout)
		print delay
		time.sleep(1)# one second
	return delay
	
ping("google.com")