Tune the UDP receive buffer

We have a sysctl tune file and option to
go higher so that we get more SLP responses.

confluent_server/confluent/discovery/protocols/slp.py

@@ -492,8 +492,10 @@ def scan(srvtypes=_slp_services, addresses=None, localonly=False):
     """
     net = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
     net4 = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
-    # TODO: increase RCVBUF to max, mitigate chance of
+    # increase RCVBUF to max, mitigate chance of
     # failure due to full buffer.
+    net.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 16777216)
+    net4.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 16777216)
     # SLP is very poor at scanning large counts and managing it, so we
     # must make the best of it
     # Some platforms/config default to IPV6ONLY, we are doing IPv4

confluent_server/setup.py.tmpl

@@ -20,6 +20,7 @@ setup(
                       'pyghmi>=0.6.5'],
     scripts=['bin/confluent', 'bin/confluentdbutil'],
     data_files=[('/etc/init.d', ['sysvinit/confluent']),
+                ('/usr/lib/sysctl.d', 'sysctl/confluent.conf'),
                 ('/usr/lib/systemd/system', ['systemd/confluent.service']),
 		('/opt/confluent/lib/python/confluent/plugins/console/', [])],
 

confluent_server/sysctl/confluent.conf

@@ -0,0 +1,2 @@
+# Increase available receive buffers for discovery scans
+net.core.rmem_max = 2097152