a3/code/jtorx/client/sender.py

   1 from scapy.all import *
   2
   3 verbose = 0
   4
   5 def vb_print(msg):
   6     global verbose
   7     if verbose == 1:
   8         print msg
   9
  10 # the sender sends packets with configurable parameters to a server and retrieves responses
  11 class Sender:
  12     # information on the SUT
  13     def __init__(self, serverIP, serverPort=8000,
  14                  networkInterface="lo", isLocal=True, senderPortMinimum=20000,
  15                  senderPortMaximum=40000, portNumberFile="sn.txt",
  16                  isVerbose=0, waitTime=1):
  17
  18
  19         # file where the last sender port used is stored
  20         self.portNumberFile = portNumberFile;
  21
  22         # when choosing a fresh port, a new port is chosen
  23         # within boundaries defined by the parameters below
  24         self.senderPortMinimum = senderPortMinimum
  25         self.senderPortMaximum = senderPortMaximum
  26
  27         # data on sender and server needed to send packets
  28         self.serverIP = serverIP
  29         self.serverPort = serverPort
  30         self.networkInterface = networkInterface
  31         self.senderPort = self.getNextPort()
  32         self.isLocal = isLocal
  33
  34         # time to wait for a response from the server before concluding a timeout
  35         self.waitTime = waitTime
  36
  37         # verbose or not
  38         self.isVerbose = isVerbose
  39
  40         # variables added so you can easily test the last system response
  41         self.lastSeqReceived = None
  42         self.lastAckReceived = None
  43         self.isTimeout = None
  44         self.lastFlagsReceived = None
  45         self.lastDataReceived = None
  46
  47
  48     # chooses a new port to send packets from
  49     def refreshNetworkPort(self):
  50         vb_print("previous local port: " + str(self.senderPort))
  51         self.senderPort = self.getNextPort()
  52         vb_print("next local port: " + str(self.senderPort) + "\n")
  53         return self.senderPort
  54
  55     # gets a new port number, an increment of the old within the specified limits. Uses a file.
  56     def getNextPort(self):
  57         f = open(self.portNumberFile, "a+")
  58         f.seek(0)
  59         line = f.readline()
  60         if line == '' or int(line) < self.senderPortMinimum:
  61             networkPort = self.senderPortMinimum
  62         else:
  63             networkPort = (int(line) + 1) % self.senderPortMaximum
  64         f.closed
  65         f = open(self.portNumberFile, "w")
  66         f.write(str(networkPort))
  67         f.closed
  68         return networkPort
  69
  70     # send a packet onto the network with the given parameters, and return the response packet
  71     # in case of a timeout, returns None, otherwise, returns the tuple (flags, seqNo, ackNo)
  72     def sendPacket(self, flagsSet, seqNr, ackNr, data = None):
  73         packet = self.createPacket(flagsSet, seqNr, ackNr, data)
  74         # consider adding the parameter: iface="ethx" if you don't receive a response. Also consider increasing the wait time
  75         scapyResponse = sr1(packet, timeout=self.waitTime, verbose=self.isVerbose)
  76         if scapyResponse is not None:
  77    #         scapyResponse.show()
  78             # ^^ in case you want to show the packet content
  79             # here is what you store from every packet response
  80             if Raw not in scapyResponse:
  81                 response = (self.intToFlags(scapyResponse[TCP].flags), scapyResponse[TCP].seq, scapyResponse[TCP].ack, None)
  82             else:
  83                 response = (self.intToFlags(scapyResponse[TCP].flags), scapyResponse[TCP].seq, scapyResponse[TCP].ack, scapyResponse[Raw].load)
  84         else:
  85             response = "Timeout"
  86         return response
  87
  88     # function that creates packet from data strings/integers
  89     # data is used for attaching data to the packet
  90     def createPacket(self, tcpFlagsSet, seqNr, ackNr, data=None):
  91         vb_print("" + tcpFlagsSet + " " + str(seqNr) + " " + str(ackNr))
  92         pIP = IP(dst=self.serverIP, flags="DF")
  93         pTCP = TCP(sport=self.senderPort,
  94         dport=self.serverPort,
  95         seq=seqNr,
  96         ack=ackNr,
  97         flags=tcpFlagsSet)
  98         if data is None:
  99             p = pIP / pTCP
 100         else:
 101             p = pIP / pTCP / Raw(load=data)
 102         return p
 103
 104     # check whether there is a 1 at the given bit-position of the integer
 105     def checkForFlag(self, x, flagPosition):
 106         if x & 2 ** flagPosition == 0:
 107             return False
 108         else:
 109             return True
 110
 111     # the flags-parameter of a network packets is returned as an int, this function converts
 112     # it to a string (such as "FA" if the Fin-flag and Ack-flag have been set)
 113     def intToFlags(self, x):
 114         result = ""
 115         if self.checkForFlag(x, 0):
 116             result = result + "F"
 117         if self.checkForFlag(x, 1):
 118             result = result + "S"
 119         if self.checkForFlag(x, 2):
 120             result = result + "R"
 121         if self.checkForFlag(x, 3):
 122             result = result + "P"
 123         if self.checkForFlag(x, 4):
 124             result = result + "A"
 125         return result
 126
 127     # sends input over the network to the server
 128     def sendInput(self, input1, seqNr, ackNr, data = None):
 129         conf.sniff_promisc = False
 130         conf.iface = self.networkInterface
 131         if self.isLocal == True:
 132             conf.L3socket = L3RawSocket  # if the connection is local/localhost, use l3 raw sockets
 133         vb_print("sending: "+ str((input1, seqNr, ackNr, data)))
 134         response = self.sendPacket(input1, seqNr, ackNr, data)
 135
 136         # updating sender state variables
 137         if response != "Timeout":
 138             (self.lastFlagsReceived, self.lastSeqReceived, self.lastAckReceived, self.lastDataReceived) = response
 139             self.isTimeout = False
 140         else:
 141             self.isTimeout = True
 142
 143         # printing response
 144         vb_print("received: "+ str(response))
 145         return response
 146
 147     # resets the connection by changing the port number. On some OSes (Win 8) upon hitting a certain number of
 148     # connections opened on a port, packets are sent to close down connections.
 149     def sendReset(self):
 150         self.refreshNetworkPort()