Cap the number of deferred packets

Prevent deferred packets from growing endlessly
if activity is keeping the loop running.

confluent_server/confluent/discovery/protocols/slp.py

@@ -482,7 +482,7 @@ def snoop(handler, protocol=None):
             known_peers = set([])
             peerbymacaddress = {}
             deferpeers = []
-            while r:
+            while r and len(deferpeers) < 256:
                 for s in r:
                     (rsp, peer) = s.recvfrom(9000)
                     if peer in known_peers:

confluent_server/confluent/discovery/protocols/ssdp.py

@@ -173,7 +173,7 @@ def snoop(handler, byehandler=None, protocol=None, uuidlookup=None):
             if r:
                 r = r[0]
             recent_peers = set([])
-            while r:
+            while r and len(deferrednotifies) < 256:
                 for s in r:
                     (rsp, peer) = s.recvfrom(9000)
                     if rsp[:4] == b'PING':