Added flow expire/stats tests

Contributions from Google test engineers.  Basic tests for flow
expiration message generation and stats checking.  They also
added code for properly managing network prototype and wildcards
for TCP/UDP packets in parse.py.
diff --git a/tests/flow_expire.py b/tests/flow_expire.py
new file mode 100644
index 0000000..cc1fee9
--- /dev/null
+++ b/tests/flow_expire.py
@@ -0,0 +1,106 @@
+"""
+Flow expire test case.
+Similar to Flow expire test case in the perl test harness.
+
+"""
+
+import logging
+
+import unittest
+import random
+
+import oftest.controller as controller
+import oftest.cstruct as ofp
+import oftest.message as message
+import oftest.dataplane as dataplane
+import oftest.action as action
+import oftest.parse as parse
+import basic
+
+from testutils import *
+from time import sleep
+
+#@var port_map Local copy of the configuration map from OF port
+# numbers to OS interfaces
+pa_port_map = None
+#@var pa_logger Local logger object
+pa_logger = None
+#@var pa_config Local copy of global configuration data
+pa_config = None
+
+def test_set_init(config):
+    """
+    Set up function for packet action test classes
+
+    @param config The configuration dictionary; see oft
+    """
+
+    global pa_port_map
+    global pa_logger
+    global pa_config
+
+    pa_logger = logging.getLogger("pkt_act")
+    pa_logger.info("Initializing test set")
+    pa_port_map = config["port_map"]
+    pa_config = config
+
+class FlowExpire(basic.SimpleDataPlane):
+    """
+    Verify flow expire messages are properly generated.
+
+    Generate a packet
+    Generate and install a matching flow with idle timeout = 1 sec
+    Verify the flow expiration message is received
+    """
+    def runTest(self):
+        global pa_port_map
+
+        of_ports = pa_port_map.keys()
+        of_ports.sort()
+        self.assertTrue(len(of_ports) > 1, "Not enough ports for test")
+
+        rc = delete_all_flows(self.controller, pa_logger)
+        self.assertEqual(rc, 0, "Failed to delete all flows")
+
+        pkt = simple_tcp_packet()
+        match = parse.packet_to_flow_match(pkt)
+        match.wildcards &= ~ofp.OFPFW_IN_PORT
+        self.assertTrue(match is not None, 
+                        "Could not generate flow match from pkt")
+        act = action.action_output()
+
+        ingress_port = pa_config["base_of_port"]
+        egress_port  = (pa_config["base_of_port"] + 1) % len(of_ports)
+        pa_logger.info("Ingress " + str(ingress_port) + 
+                       " to egress " + str(egress_port))
+        
+        match.in_port = ingress_port
+        
+        request = message.flow_mod()
+        request.match = match
+        request.cookie = random.randint(0,9007199254740992)
+        request.buffer_id = 0xffffffff
+        request.idle_timeout = 1
+        request.flags |= ofp.OFPFF_SEND_FLOW_REM
+        act.port = egress_port
+        self.assertTrue(request.actions.add(act), "Could not add action")
+        
+        pa_logger.info("Inserting flow")
+        rv = self.controller.message_send(request)
+        self.assertTrue(rv != -1, "Error installing flow mod")
+        do_barrier(self.controller)
+
+        (response, raw) = self.controller.poll(ofp.OFPT_FLOW_REMOVED, 2)
+        
+        self.assertTrue(response is not None, 
+                        'Did not receive flow removed message ')
+
+        self.assertEqual(request.cookie, response.cookie,
+                         'Cookies do not match')
+
+        self.assertEqual(ofp.OFPRR_IDLE_TIMEOUT, response.reason,
+                         'Flow table entry removal reason is not idle_timeout')
+
+        self.assertEqual(match, response.match,
+                         'Flow table entry does not match')
+