Python Socket Programming Assignment - UDP Heartbeat Pinger

I have an assigment to create a UDP heartbeat pinger. (PYTHON 2.7)

I am receiving the following message "The datatype supported by this server is string. Given data is "

I have attempted converting to string but appear to be having trouble. Any help would be appreciated.

Here is the assignment's description:

The client sends a sequence number and current timestamp in the UDP packet to the server, which is listening for the Heartbeat (i.e., the UDP packets) of the client. Upon receiving the packets, the server calculates the time difference and reports any lost packets. If the Heartbeat packets are missing for some specified period of time, we can assume that the client application has stopped.

Implement the UDP Heartbeat (both client and server). You will need to modify the given UDPPingerServer.py, and your UDP ping client.

Here my code:

UDP Client:

from socket import *

import datetime as dt

import time

import argparse

clientSocket = socket(AF_INET, SOCK_DGRAM)

# Initializing parser for accepting command line arguements

parser = argparse.ArgumentParser(description="""UDP Heartbeat Client. Simulates sending and receiving packets to and from the server \ To close the client socket, press 'Ctrl + C'""")

# Assign server's IP address obtained from the command line

parser.add_argument('--serverip', metavar='str', type=str,help="The server's IP address. A required value. Format: a.b.c.d, where a,b,c and d are within the range 0-255")

parser.add_argument('--serverport', metavar='int', type=int,help="The server's port. A required value. Range: 1024 to 65535")

args = parser.parse_args()

serverip = '127.0.0.1'

args.serverip = '127.0.0.1'

args.serverport = 12000

if args.serverip == None:

print 'IP address of server is missing. Use the flag -h to print help'

clientSocket.close()

exit()

elif args.serverport == None:

print 'Port number of server is missing. Use the flag -h to print help'

clientSocket.close()

exit()

elif args.serverport < 1024 or args.serverport > 65535 or len(args.serverip) < 7 or len(args.serverip) > 15:

print 'Invalid value for argument. Please execute with -h flag for help regarding the value ranges of arguments to be passed'

clientSocket.close()

exit()

# Create a UDP socket

clientSocket = socket(AF_INET, SOCK_DGRAM)

port = 12000

flag = True

while flag:

try:

# Bind server to port

clientSocket.bind(('', port))

print 'Client bound to port', port

flag = False

except IOError:

print 'Cannot bind client to port',port,'. Trying with the next one...'

port+=1

except OverflowError:

port = 1024

# A variable to hold the count of number of pings sent

scount = 0

# A variable to hold the count of number of pings received

rcount = 0

# Initialize the sequence number

seq = 1

while True:

try:

now = dt.datetime.now()

# Set timeout for socket operations

clientSocket.settimeout(1)

# Create a message with first part as a sequence number and second part as the timestamp separated by a whitespace tab character

clientSocket.sendto(( str(seq) + '\t' + str(now) ), (args.serverip,args.serverport))

print "PING",args.serverip,':',args.serverport,"at",str(now)

scount+=1

# Receive the client packet along with the address it is coming from

message, address = clientSocket.recvfrom(1024)

print message

rcount+=1

# Increment the sequence number

seq+=1

time.sleep(3)

except TypeError:

print "Server sent an unexpected response"

break

except Exception as e:

print e

except KeyboardInterrupt:

print ' Safely shutting down the client'

print "Statistics:"

print "Packets Sent:",scount

print "Packets Received",rcount

print "Percentage Packet Loss",((1-(rcount/(scount*1.0)))*100),"%"

break

clientSocket.close()

UDP Server:

import random

from socket import *

import datetime as dt

import argparse

# Create a UDP socket

serverSocket = socket(AF_INET, SOCK_DGRAM)

# Initializing parser for accepting command line arguements

parser = argparse.ArgumentParser(

description="""UDP Heartbeat Server. Simulates packet loss and supports user defined value for the port number. \

To close the server, press 'Ctrl + C'""",

usage="./Heartbeat.py [--port] N [--packetloss] N [-h/--help]")

# Assign port number to socket

parser.add_argument(

'--port', default=12000, type=int, metavar='int',

help='The port where the server should run (integer > 1024 and < 65535) Default: 12000')

# Assign packetloss percentage

parser.add_argument(

'--packetloss', default=40, type=int, metavar='int',

help='Percentage of data loss experienced by the server (Simulated) Default: 40%')

try:

args = parser.parse_args()

except ValueError:

print "Usage: ./Heartbeat.py [--port] N [--packetloss] N [-h/--help]"

exit()

if args.port < 1024 or args.port > 65535:

print 'Invalid port number. Value must be within the range 1024-65535'

exit()

if args.packetloss < 0 or args.packetloss > 100:

print 'Invalid value for packet loss percentage. Value must be in between 0 to 100'

exit()

# Variable has to be initialized outside so as to be able to use everywhere in the program

server_start = dt.datetime.now()

if args.port == 12000:

# I have taken a default value and it is my headache to make sure it works

def portassign():

"""A function to make sure the server binds to a free port in case the user hasn't specified one on his own"""

flag = True

while flag:

try:

# Bind server to port

serverSocket.bind(('', args.port))

# Record the time at which the server started

server_start = dt.datetime.now()

print 'Serving on host at port', args.port,'with a packet loss simulation of',args.packetloss,'%'

flag = False

except IOError:

print 'Unsuccessful in binding server to port',args.port,'. Trying with another one..'

args.port += 1

except OverflowError:

port = 1024

portassign()

else:

try:

# Bind server to port

serverSocket.bind(('127.0.0.1', args.port))

# Record the time at which the server started

server_start = dt.datetime.now()

print 'Serving on host at port', args.port,'with a packet loss simulation of',args.packetloss,'%'

except IOError:

# The user has specified the port number.

# We should allow him to specify an alternative rather than take matters into our own hands

print 'Cannot bind server to port',args.port,'. Try with another one'

exit()

# Multiple clients may access the server

# So maintain a dictionary (table) with IP address of the client as key

# and a list with fields as

# 1: the number of packets received as value

# 2: The lost packet count

# 3: Timestamp of last received heartbeat

iptable = dict()

# This is another dictionary that holds the number of packets lost between two successive replies

# for a particular address

packets_lost = dict()

while True:

try:

# If no client pings the server for a whole minute, we have to assume that all clients are closed

serverSocket.settimeout(60)

# Generate random number in the range of 0 to 100

rand = random.randint(0, 100)

# Receive the client packet along with the address it is coming from

message, address = serverSocket.recvfrom(1024)

# The client is sending us a message with sequence number and a timestamp separated by a whitespace tab character

# We need to split it by the whitespace tab character to extract the timestamp

message_list = message.split('\t')

message = dt.datetime.strptime(message_list[1],"%Y-%m-%d %H:%M:%S.%f")

try:

# If the client is pinging the server for the first time, create a key for its address

if not address in iptable:

iptable[address] = [0,0,0]

# iptable[address][0] --> No of packets received

# iptable[address][1] --> Lost packet count

# iptable[address][2] --> Timestamp of last heartbeat

packets_lost[address] = 0

# A new packet has been received, so the value has to be incremented

iptable[address][0] += 1

# Human readable console response

print 'Received packet no',iptable[address][0],'from',address,'.',

print 'The sequence number sent with the packet was',message_list[0]

now = dt.datetime.now()

# Delay between the time at which the client sent the packet and the time server received it

tempresponse = now - message

response = dt.datetime.strptime(tempresponse)

# Timestamp of most recent ping from the client

iptable[address][2] = now

# If rand is less is than the arguement packetloss, we consider the packet lost and do not respond

if rand < args.packetloss:

print 'Simulating packet loss for',address[0], ':', address[1]

# Increment the value of total packets lost for the address

iptable[address][1]+=1

# Increment the value of packets lost in between two successful replies

# Needed to report to the client

packets_lost[address] += 1

continue

# Otherwise, the server responds by replying with the time difference and a report of lost packets

reply = "Packet delivery delay = "+str(response)+", Number of packets lost in between = "+ packets_lost[address]

# Reset packets_lost's value. We are restarting the counter for that address

packets_lost[address] = 0

serverSocket.sendto(reply, address)

print 'Sent response to',address,'with a delay of',str(response.total_seconds())

# The client may send a packet with invalid data either mistakenly or with a mischievious attempt at breaking the server.

# This except block replies with a response and makes sure that server doesn't break down

except TypeError:

print 'Client at',address,'sent an unrecognized packet. Replying with an appropriate response'

response = 'The datatype supported by this server is string. Given data is'+str(type(message))

serverSocket.sendto(response,address)

# The server can be closed with a keyboard interrupt. But before exiting, the socket must be safely closed for security reasons

# Optional feature addition is to print a report of all the clients who pinged and some additional information

except KeyboardInterrupt:

print ' Safely closing down the server...'

# It should exit with a status summary of no of packets received from each client in a tabular format

def decor():

"""Decoration for Status Summary"""

for i in range(0,70):

print '-',

print

decor()

print "Summary"

decor()

server_end = dt.datetime.now()

print "Server started serving on port",args.port,"on",server_start,"and is exiting on",server_end

print "Server ran for a duration of",( server_end - server_start )

print "NOTE: The packetloss percentage is only for studying the simulation.",

print "Real life UDP server wouldn't know and wouldn't care about packetloss"

decor()

print "Client\t\t\tNumber of Packets Received\tPacket loss percentage\tLast Heartbeat received at"

decor()

for key in iptable:

percentage = ((int(iptable[key][1])) / (int(iptable[key][0]) * 1.0) * 100)

print key,"\t",iptable[key][0],"\t\t\t\t",("%.2f" %percentage) ,"%\t\t\t", iptable[key][2]

print ''

decor()

break;

except Exception as e:

if type(e) == timeout:

print "NOTE: It's been a whole minute since the last client pinged the server.",

print "If there are no more clients to test the server with, you can close the server with Ctrl+C key stroke"

else:

print e