Question

Develop a Traceroute application in python using ICMP. Your application will use ICMP but, in order to keep it simple, will not exactly follow the official specification in RFC 1739..

Below you will find the skeleton code for the client. You are to complete the skeleton code. The places where you need to fill in code are marked with #Fill in start and #Fill in end.

Code

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

ICMP_ECHO_REQUEST = 8
MAX_HOPS = 30
TIMEOUT = 2.0
TRIES = 2


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 build_packet(data_size):
    # First, make the header of the packet, then append the checksum to the header,
    # then finally append the data

    # Dont send the packet yet, just return the final packet in this function.
    # So the function ending should look like this
    # Note: padding = bytes(data_size)
    packet = header + data + padding
    return packet


def get_route(hostname, data_size):
    timeLeft = TIMEOUT
    for ttl in range(1, MAX_HOPS):
        for tries in range(TRIES):

            destAddr = gethostbyname(hostname)

            # SOCK_RAW is a powerful socket type. For more details:   http://sock-raw.org/papers/sock_raw
            # Fill in start
            # Make a raw socket named mySocket
            # Fill in end

            # setsockopt method is used to set the time-to-live field.
            mySocket.setsockopt(IPPROTO_IP, IP_TTL, struct.pack('I', ttl))
            mySocket.settimeout(TIMEOUT)
            try:
                d = build_packet(data_size)
                mySocket.sendto(d, (hostname, 0))
                t = time.time()
                startedSelect = time.time()
                whatReady = select.select([mySocket], [], [], timeLeft)
                howLongInSelect = (time.time() - startedSelect)
                if whatReady[0] == []:  # Timeout
                    print("  *        *        *    Request timed out.")
                recvPacket, addr = mySocket.recvfrom(1024)
                timeReceived = time.time()
                timeLeft = timeLeft - howLongInSelect
                if timeLeft <= 0:
                    print("  *        *        *    Request timed out.")

            except timeout:
                continue

            else:
                # Fill in start
                # Fetch the icmp type from the IP packet
                # Fill in end

                if types == 11:
                    bytes = struct.calcsize("d")
                    timeSent = struct.unpack("d", recvPacket[28:28 + bytes])[0]
                    print("  %d    rtt=%.0f ms    %s" % (ttl, (timeReceived - t) * 1000, addr[0]))

                elif types == 3:
                    bytes = struct.calcsize("d")
                    timeSent = struct.unpack("d", recvPacket[28:28 + bytes])[0]
                    print("  %d    rtt=%.0f ms    %s" % (ttl, (timeReceived - t) * 1000, addr[0]))

                elif types == 0:
                    bytes = struct.calcsize("d")
                    timeSent = struct.unpack("d", recvPacket[28:28 + bytes])[0]
                    print("  %d    rtt=%.0f ms    %s" % (ttl, (timeReceived - timeSent) * 1000, addr[0]))
                    return

                else:
                    print("error")
                break
            finally:
                mySocket.close()


print('Argument List: {0}'.format(str(sys.argv)))

data_size = 0
if len(sys.argv) >= 2:
    data_size = int(sys.argv[1])

get_route("google.com", data_size)

Answer 1

Your code is completely coped and whereever the new code is to be inserted, it is done. Please see to that.

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

ICMP_ECHO_REQUEST = 8
MAX_HOPS = 30
TIMEOUT = 2.0
TRIES = 2

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 build_packet(data_size):
# First, make the header of the packet, then append the checksum to the header,
# then finally append the data

# Dont send the packet yet, just return the final packet in this function.
# So the function ending should look like this
# Note: padding = bytes(data_size)
packet = header + data + padding
return packet

def get_route(hostname, data_size):
timeLeft = TIMEOUT
for ttl in range(1, MAX_HOPS):
for tries in range(TRIES):

destAddr = gethostbyname(hostname)

# SOCK_RAW is a powerful socket type. For more details: http://sock-raw.org/papers/sock_raw
# Fill in start
# Make a raw socket named mySocket
icmp = socket.getprotobyname("icmp")
mySocket = socket.socket(socket.AF_INET, socket.SOCK_RAW, icmp)

# Fill in end

# setsockopt method is used to set the time-to-live field.
mySocket.setsockopt(IPPROTO_IP, IP_TTL, struct.pack('I', ttl))
mySocket.settimeout(TIMEOUT)
try:
d = build_packet(data_size)
mySocket.sendto(d, (hostname, 0))
t = time.time()
startedSelect = time.time()
whatReady = select.select([mySocket], [], [], timeLeft)
howLongInSelect = (time.time() - startedSelect)
if whatReady[0] == []: # Timeout
print(" * * * Request timed out.")
recvPacket, addr = mySocket.recvfrom(1024)
timeReceived = time.time()
timeLeft = timeLeft - howLongInSelect
if timeLeft <= 0:
print(" * * * Request timed out.")

except timeout:
continue

else:
# Fill in start
# Fetch the icmp type from the IP packet
icmpHeaderContent = recvPacket[20:28]
type, code, checksum, packetID, sequence = struct.unpack("bbHHh", icmpHeaderContent)
printname = get_name_or_ip(addr[0])
# Fill in end

if types == 11:
bytes = struct.calcsize("d")
timeSent = struct.unpack("d", recvPacket[28:28 + bytes])[0]
print(" %d rtt=%.0f ms %s" % (ttl, (timeReceived - t) * 1000, addr[0]))

elif types == 3:
bytes = struct.calcsize("d")
timeSent = struct.unpack("d", recvPacket[28:28 + bytes])[0]
print(" %d rtt=%.0f ms %s" % (ttl, (timeReceived - t) * 1000, addr[0]))

elif types == 0:
bytes = struct.calcsize("d")
timeSent = struct.unpack("d", recvPacket[28:28 + bytes])[0]
print(" %d rtt=%.0f ms %s" % (ttl, (timeReceived - timeSent) * 1000, addr[0]))
return

else:
print("error")
break
finally:
mySocket.close()

print('Argument List: {0}'.format(str(sys.argv)))

data_size = 0
if len(sys.argv) >= 2:
data_size = int(sys.argv[1])

get_route("google.com", data_size)