Hi I have a funciton act_like_switch defined below.
def act_like_switch (self, packet, packet_in):
"""
Implement switch-like behavior.
"""
# Learn the port for the source MAC
#print "RECIEVED FROM PORT ",packet_in.in_port , "SOURCE ",packet.src
# create a Session
#Session = sessionmaker(bind=engine)
#session = Session()
self.mac_to_port[packet.src]=packet_in.in_port
#if self.mac_to_port.get(packet.dst)!=None:
#print "count for
dst",session.query(SourcetoPort).filter_by(src_address=str(packet.dst)).count(),str(packet.dst)
#if
session.query(SourcetoPort).filter_by(src_address=str(packet.dst)).count():
if session.query(exists().where(SourcetoPort.src_address ==
str(packet.dst))).scalar() is not None:
#send this packet
print "got info from the database"
q_res =
session.query(SourcetoPort).filter_by(src_address=str(packet.dst)).first()
self.send_packet(packet_in.buffer_id,
packet_in.data,q_res.port_no, packet_in.in_port)
#create a flow modification message
msg = of.ofp_flow_mod()
#set the fields to match from the incoming packet
msg.match = of.ofp_match.from_packet(packet)
#send the rule to the switch so that it does not query the
controller again.
msg.actions.append(of.ofp_action_output(port=q_res.port_no))
#push the rule
self.connection.send(msg)
else:
#flood this packet out as we don't know about this node.
print "flooding the first packet"
self.send_packet(packet_in.buffer_id, packet_in.data,
of.OFPP_FLOOD, packet_in.in_port)
#self.matrix[(packet.src,packet.dst)]+=1
entry = SourcetoPort(src_address=str(packet.src) ,
port_no=packet_in.in_port)
#add the record to the session object
session.add(entry)
#add the record to the session object
session.commit()
I am first checking if the specified mac address exists in the database
if session.query(exists().where(SourcetoPort.src_address ==
str(packet.dst))).scalar() is not None:
If it does I am doing a query to retrieve the information as below.
q_res =
session.query(SourcetoPort).filter_by(src_address=str(packet.dst)).first()
self.send_packet(packet_in.buffer_id, packet_in.data,q_res.port_no,
packet_in.in_port)
for some reason query is returning a none object.I don't know why after the
if condition above succeeds.Any help is appreciated.
Regards,
Karthik.
