Fix race condition in SSDP snoop

If an asynchronous handler is slow to
enroll a target while another target causes an iteration
of the snoop loop, the various modified structures
had been discarded in the interim.

Now persist the data structures iteration to iteration,
using 'clear()' to empty them rather than getting
brand new data structures each loop.

confluent_server/confluent/discovery/protocols/ssdp.py

@@ -116,10 +116,11 @@ def _process_snoop(peer, rsp, mac, known_peers, newmacs, peerbymacaddress, byeha
                 if '/eth' in value and value.endswith('.xml'):
                     targurl = '/redfish/v1/'
                     targtype = 'megarac-bmc'
-                    continue # MegaRAC redfish
+                    continue  # MegaRAC redfish
                 elif value.endswith('/DeviceDescription.json'):
                     targurl = '/DeviceDescription.json'
-                    targtype = 'megarac-bmc'
+                    targtype = 'lenovo-xcc'
+                    continue
                 else:
                     return
         if handler and targurl:
@@ -179,11 +180,14 @@ def snoop(handler, byehandler=None, protocol=None, uuidlookup=None):
     net4.bind(('', 1900))
     net6.bind(('', 1900))
     peerbymacaddress = {}
+    newmacs = set([])
+    deferrednotifies = []
+    machandlers = {}
     while True:
         try:
-            newmacs = set([])
-            deferrednotifies = []
-            machandlers = {}
+            newmacs.clear()
+            deferrednotifies.clear()
+            machandlers.clear()
             r = select.select((net4, net6), (), (), 60)
             if r:
                 r = r[0]