Per #15 Cleaned up serialToTUN()

* Clarified port and IP addressing with TUN
* Removed hardcoded values where possible.
* Used mtu value from Monitor
* Passes local pytest and linting

tests/test_tun.py

@@ -143,32 +143,28 @@ def test_serialToTUN():
     # Configure TUN IP:PORT and IP Packet source IP:PORT parameters for test
     sourceAddress = '10.0.0.2'
     sourcePort = 9998
-    tunAddress = '10.0.0.1'
-    tunPort = 9999
+    destPort = 9999
 
     # Start a TUN Monitor class
-    TUNMonitor = faraday.Monitor(serialPort=serialPort,
-                                 name="Faraday",
-                                 addr=tunAddress,
-                                 mtu=1500)
+    TUNMonitor = faraday.Monitor(serialPort=serialPort)
 
     # Open a socket for UDP packets and bind it to the TUN address:port
     s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
-    s.bind(('10.0.0.1', 9999))
+    s.bind((TUNMonitor._TUN._tun.addr, destPort))
 
     # Create simple IP packet with message. Send to TUN address:port
     message = bytes("Hello, World! {0}".format(time.time()), "utf-8")
     etherType = b"\x00\x00\x08\x00"
-    packet = etherType + (IP(dst=tunAddress,
+    packet = etherType + (IP(dst=TUNMonitor._TUN._tun.addr,
                              src=sourceAddress) /
                           UDP(sport=sourcePort,
-                              dport=tunPort)/message).__bytes__()
+                              dport=destPort)/message).__bytes__()
 
     # Write a simple message over the TUN, no need for checker thread
     TUNMonitor._TUN._tun.write(packet)
 
     # Receive data from the socket bound to the TUN address:port
-    data, address = s.recvfrom(4096)
+    data, address = s.recvfrom(TUNMonitor._TUN._tun.mtu)
 
     # Check that data written to TUN matches data received from socket
     assert data == message