Select return empty object (socket programing in python)

1

I'm currently writing a relatively basic Socket program in python which is a Ping application using ICMP request and reply messages. i am getting a error that select.select() in receiveOnePing() function return empty object . How can i fix it?

This is what I currently get as output:

([], [], [])

RTT: 0: Destination Network Unreachable,

Package Lose Rate: 0

this is my code

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

ICMP_ECHO_REQUEST = 8
timeRTT = []
packageSent =0
packageRev = 0

def checksum(string):
    csum = 0
    countTo = (len(string) // 2) * 2
    count = 0
    while count < countTo:
        thisVal = ord(string[count+1]) * 256 + ord(string[count])
        csum = csum + thisVal
        csum = csum & 0xffffffff
        count = count + 2
    if countTo < len(string):
        csum = csum + ord(string[len(string) - 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):
    global packageRev,timeRTT
    timeLeft = timeout
    while 1:
        startedSelect = time.time()

        whatReady = select.select([mySocket], [], [], timeLeft)
        print(whatReady)

        howLongInSelect = (time.time() - startedSelect)
        if whatReady[0] == []: # Timeout
            return "0: Destination Network Unreachable,"
        timeReceived = time.time()
        recPacket, addr = mySocket.recvfrom(1024)
        #Fill in start
        #Fetch the ICMP header from the IP packet
        icmpHeader = recPacket[20:28]
        requestType, code, revChecksum, revId, revSequence = struct.unpack('bbHHh',icmpHeader)
        if ID == revId:
            bytesInDouble = struct.calcsize('d')
            timeData = struct.unpack('d',recPacket[28:28 + bytesInDouble])[0]
            timeRTT.append(timeReceived - timeData)
            packageRev += 1
            return timeReceived - timeData
        else:
            return "ID is not the same!"
        #Fill in end
        timeLeft = timeLeft - howLongInSelect
        if timeLeft <= 0:
            return "1: Destination Host Unreachable."
def sendOnePing(mySocket, destAddr, ID):
    global packageSent
    # Header is type (😎, code (😎, 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(str(header + data))
    # Get the right checksum, and put in the header
    if sys.platform == 'darwin':
        myChecksum = socket.htons(myChecksum) & 0xffff
        #Convert 16-bit integers from host to network byte order.
    else:
        myChecksum = socket.htons(myChecksum)
    header = struct.pack("bbHHh", ICMP_ECHO_REQUEST, 0, myChecksum, ID, 1)
    packet = header + data
    mySocket.sendto(packet, (destAddr, 1))
    packageSent += 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 = socket.getprotobyname("icmp")
#SOCK_RAW is a powerful socket type. For more details see:http://sock-raw.org/papers/sock_raw
    #Fill in start
    #Create Socket here
    try:
        mySocket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)
       # conn, addr = mySocket.accept()
    except socket.error (errno, msg):
        if errno == 1:
            raise socket.error(msg)
    #Fill in end
    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,
    dest = socket.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("RTT:",delay)
        print("Package Lose Rate:", ((packageSent - packageRev)/packageSent if packageRev > 0 else 0))
        time.sleep(1)# one second
    return delay
ping("www.google.com") ```
python
asked on Stack Overflow May 9, 2021 by toan chu van • edited May 9, 2021 by toan chu van

0 Answers

Nobody has answered this question yet.


User contributions licensed under CC BY-SA 3.0