I am quite new to python and to sqlalchemy.I have written the following
netowrk program.
class SourcetoPort(Base):
""""""
__tablename__ = 'source_to_port'
id = Column(Integer, primary_key=True)
port_no = Column(Integer)
src_address = Column(String)
#----------------------------------------------------------------------
def __init__(self, src_address,port_no):
""""""
self.src_address = src_address
self.port_no = port_no
############################################################################################
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
Session = sessionmaker(bind=engine)
session = Session()
self.mac_to_port[packet.src]=packet_in.in_port
if(self.matrix.get((packet.src,packet.dst))==None):
# create a Session
#print "creating a db session"
#Session = sessionmaker(bind=engine)
#session = Session()
self.matrix[(packet.src,packet.dst)]=0
# Create an entry with address and port
print "creating a new db entry"
entry = SourcetoPort(src_address="packet.src" ,
port_no=packet_in.in_port)
# Add the record to the session object
session.add(entry)
session.commit()
self.matrix[(packet.src,packet.dst)]+=1
#if self.mac_to_port.get(packet.dst)!=None:
if
session.query(SourcetoPort).filter_by(src_address=packet.dst).all():
#send this packet
self.send_packet(packet_in.buffer_id,
packet_in.data,self.mac_to_port[packet.dst], 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)
#print "SENDING TO PORT " + str(self.mac_to_port[packet.dst]),
packet.dst
# send the rule to the switch so that it does not query the
controller again.
msg.actions.append(of.ofp_action_output(port=self.mac_to_port[packet.dst]))
# push the rule
self.connection.send(msg)
else:
#print 'flooding the packet '
# Flood this packet out as we don't know about this node.
self.send_packet(packet_in.buffer_id, packet_in.data,
of.OFPP_FLOOD, packet_in.in_port)
In the above code the line
if
session.query(SourcetoPort).filter_by(src_address='packet.dst').all():
does not work as I expect it.What I expect is that it should retrive the
entry from sqlalchemy database and if it succeeds (as the output is not
NONE) it should execute the following code.
When I try to print that line using print
print "session query",
session.query(SourcetoPort).filter_by(src_address='packet.dst').all()
The output that I get is
session query []
Am I doing something wrong.It would be great if someone could point this
out.
If I change the above line based on the suggestion as
print
session.query(SourcetoPort).filter_by(src_address=packet.dst).count()
I get the following error:
creating a new db entry
RECIEVED FROM PORT 2 SOURCE 96:74:ba:a9:92:b9
creating a new db entry
ERROR:core:Exception while handling Connection!PacketIn...
Traceback (most recent call last):
File "ws_thesis/pox/pox/lib/revent/revent.py", line 234, in
raiseEventNoErrors
return self.raiseEvent(event, *args, **kw)
File "ws_thesis/pox/pox/lib/revent/revent.py", line 281, in raiseEvent
rv = event._invoke(handler, *args, **kw)
File "ws_thesis/pox/pox/lib/revent/revent.py", line 159, in _invoke
return handler(self, *args, **kw)
File "ws_thesis/pox/tutorial.py", line 137, in _handle_PacketIn
self.act_like_switch(packet, packet_in)
File "ws_thesis/pox/tutorial.py", line 101, in act_like_switch
print
session.query(SourcetoPort).filter_by(src_address=packet.dst).count()
File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line
2400, in count
return self.from_self(col).scalar()
File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line
2045, in scalar
ret = self.one()
File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line
2014, in one
ret = list(self)
File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line
2057, in __iter__
return self._execute_and_instances(context)
File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/query.py", line
2072, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py",
line 1405, in execute
