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") ```
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