server.py

from socket import * 
import os 
import sys 
import struct 
import time 
import select 
import binascii   
 
ICMP_ECHO_REQUEST = 8 


def checksum(str_):
    # In this function we make the checksum of our packet 
    str_ = bytearray(str_)
    csum = 0
    countTo = (len(str_) // 2) * 2

    for count in range(0, countTo, 2):
        thisVal = str_[count+1] * 256 + str_[count]
        csum = csum + thisVal
        csum = csum & 0xffffffff

    if countTo < len(str_):
        csum = csum + str_[-1]
        csum = csum & 0xffffffff

    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 ICMP header from the IP packet 
        icmpHeader = recPacket[20:28]
        icmpType, code, mychecksum, packetID, sequence = struct.unpack("bbHHh", icmpHeader)
        if icmpType!=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 "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://sockraw.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("127.0.0.1")