main.py

"""Main module of amlight/sdntrace_cp Kytos Network Application.

Run tracepaths on OpenFlow in the Control Plane
"""

from datetime import datetime

from flask import jsonify, request
from kytos.core import KytosEvent, KytosNApp, log, rest
from kytos.core.helpers import listen_to
from napps.amlight.flow_stats.main import Main as FlowManager
from napps.amlight.sdntrace_cp import settings
from napps.amlight.sdntrace_cp.automate import Automate
from napps.amlight.sdntrace_cp.utils import (convert_entries, find_endpoint,
                                             prepare_json)


class Main(KytosNApp):
    """Main class of amlight/sdntrace_cp NApp.

    This application gets the list of flows from the switches
    and uses it to trace paths without using the data plane.
    """

    def setup(self):
        """Replace the '__init__' method for the KytosNApp subclass.

        The setup method is automatically called by the controller when your
        application is loaded.

        """
        log.info("Starting Kytos SDNTrace CP App!")

        self.traces = {}
        self.last_id = 30000
        self.automate = Automate(self)
        if settings.TRIGGER_SCHEDULE_TRACES:
            event = KytosEvent('amlight/scheduler.add_job')
            event.content['id'] = 'automatic_traces'
            event.content['func'] = self.automate.run_traces
            try:
                trigger = settings.SCHEDULE_TRIGGER
                kwargs = settings.SCHEDULE_ARGS
            except AttributeError:
                trigger = 'interval'
                kwargs = {'seconds': 60}
            event.content['kwargs'] = {'trigger': trigger}
            event.content['kwargs'].update(kwargs)
            self.controller.buffers.app.put(event)
        if settings.TRIGGER_IMPORTANT_CIRCUITS:
            event = KytosEvent('amlight/scheduler.add_job')
            event.content['id'] = 'automatic_important_traces'
            event.content['func'] = self.automate.run_important_traces
            try:
                trigger = settings.IMPORTANT_CIRCUITS_TRIGGER
                kwargs = settings.IMPORTANT_CIRCUITS_ARGS
            except AttributeError:
                trigger = 'interval'
                kwargs = {'minutes': 10}
            event.content['kwargs'] = {'trigger': trigger}
            event.content['kwargs'].update(kwargs)
            self.controller.buffers.app.put(event)

    def execute(self):
        """This method is executed right after the setup method execution.

        You can also use this method in loop mode if you add to the above setup
        method a line like the following example:

            self.execute_as_loop(30)  # 30-second interval.
        """

    def shutdown(self):
        """This method is executed when your napp is unloaded.

        If you have some cleanup procedure, insert it here.
        """
        event = KytosEvent('amlight/scheduler.remove_job')
        event.content['id'] = 'automatic_traces'
        self.controller.buffers.app.put(event)
        event = KytosEvent('amlight/scheduler.remove_job')
        event.content['id'] = 'automatic_important_traces'
        self.controller.buffers.app.put(event)

    @rest('/trace', methods=['PUT'])
    def trace(self):
        """Trace a path."""
        entries = request.get_json()
        result = self.tracepath(entries)
        return jsonify(prepare_json(result))

    def tracepath(self, entries):
        """Trace a path for a packet represented by entries."""
        self.last_id += 1
        trace_id = self.last_id
        entries = convert_entries(entries)
        trace_result = []
        trace_type = 'starting'

        do_trace = True
        while do_trace:
            trace_step = {'in': {'dpid': entries['dpid'],
                                 'port': entries['in_port'],
                                 'time': str(datetime.now()),
                                 'type': trace_type}}
            if 'vlan_vid' in entries:
                trace_step['in'].update({'vlan': entries['vlan_vid'][-1]})
            switch = self.controller.get_switch_by_dpid(entries['dpid'])
            result = self.trace_step(switch, entries)
            if result:
                out = {'port': result['out_port']}
                if 'vlan_vid' in result['entries']:
                    out.update({'vlan': result['entries']['vlan_vid'][-1]})
                trace_step.update({
                    'out': out
                })
                if 'dpid' in result:
                    next_step = {'dpid': result['dpid'],
                                 'port': result['in_port']}
                    if self.has_loop(next_step, trace_result):
                        do_trace = False
                    else:
                        entries = result['entries']
                        entries['dpid'] = result['dpid']
                        entries['in_port'] = result['in_port']
                        trace_type = 'trace'
                else:
                    do_trace = False
            else:
                do_trace = False
            trace_result.append(trace_step)
        self.traces.update({
            trace_id: trace_result
        })
        return trace_result

    @staticmethod
    def has_loop(trace_step, trace_result):
        """Check if there is a loop in the trace result."""
        for trace in trace_result:
            if trace['in']['dpid'] == trace_step['dpid'] and \
                            trace['in']['port'] == trace_step['port']:
                return True
        return False

    @staticmethod
    def trace_step(switch, entries):
        """Perform a trace step.

        Match the given fields against the switch's list of flows."""
        flow, entries, port = FlowManager.match_and_apply(switch, entries)
        if not flow or not port:
            return None

        endpoint = find_endpoint(switch, port)
        if endpoint is None:
            return {'out_port': port,
                    'entries': entries}

        return {'dpid': endpoint.switch.dpid,
                'in_port': endpoint.port_number,
                'out_port': port,
                'entries': entries}

    @listen_to('amlight/flow_stats.flows_updated')
    def update_circuits(self, event):
        """Update the list of circuits after a flow change."""
        # pylint: disable=unused-argument
        if settings.FIND_CIRCUITS_IN_FLOWS:
            self.automate.find_circuits()