def PingClient(self, server, message):
'''
PingClient - Client portion of PingServer
Sends a standardized message to the PingServer and deals with
dropped packets as defined by the timeout value passed to NetDefs
(my standard network connection module).
Right now, the connection timeout is set to 1 second...
'''
# Import the required classes
from NetDefs import Udp
from socket import timeout
# Build the connection and write the message passed
connection = Udp(server = server, port = self.port)
connection.write(message)
# Try to read from the socket after we send a message
# capture the timeout exception and handle.
try:
retMsg = connection.read(1.0)
except timeout:
retMsg = 'TIMEOUT: No return received'
# Return any message received.
return(retMsg)
def PingServer(self):
'''
PingServer - start a UDP server to listen on a specified port for 'ping'
messages. Assumes a message input standard of:
PING <seq no.> <client orig time> CRLF
Returns message in format of:
PING <client seq no.> <client orig time> <server reply time> CRLF
PingServer simulates pseudo-random packet loss (via LOSS_RATE) and
randomized process/transmit delay (via AVERAGE_DELAY) for the packet
'''
# Import the classes/modules
from NetDefs import Udp
from random import random
from re import match
from time import sleep
from Generic import Generic
# Loop forever...or there about...
while(True):
# Establish the listener locally
connection = Udp(port = self.port)
connection.listen()
# Generate a random number to simulate packet loss
simulate_loss = random()
# Read the port
recvStr = connection.read()
print('Got message ' + recvStr.rstrip('\n') + ' from ' + connection.serverAddress[0])
# if the message matches exactly the kill string stop the server
if(match(self.killerPattern,recvStr)):
break
# If the simulated loss is below the LOSS_RATE, drop
if(simulate_loss < self.LOSS_RATE):
print('Dropping packet (on purpose)')
print('\tDropped packet contained: ' + recvStr.rstrip('\n'))
print('\tDropped packet was from: ' + connection.serverAddress[0] + '\n')
continue
# Sleep to simulate network delay
print('Sleeping for ' + str(((2*simulate_loss)*self.AVERAGE_DELAY)/1000) + ' sec')
sleep(((2*simulate_loss)*self.AVERAGE_DELAY)/1000)
# Instantiate a generic instance for all methods
g = Generic()
# Strip off the CRLF from the inbound
sndStr = recvStr.rstrip('\n')
# Write the original data back to the pinger
# Need to set up the connection information from the received
# packet
connection.server = connection.serverAddress[0]
connection.port = connection.serverAddress[1]
connection.write(sndStr + ' ' + g.timeStamp() + '\n')
# Notify that message was sent back
print('Reply sent to ' + connection.serverAddress[0] + '\n')
# Return if the request to kill the server is received
return
