shortestpath.py

'''
ryu-manager --ofp-tcp-listen-port 6633 --observe-links shortestpath.py ryu.app.ofctl_rest
'''

from loghandler import Logger
import struct

from ryu.base import app_manager
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_DISPATCHER, CONFIG_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_0
from ryu.lib.mac import haddr_to_bin
from ryu.lib.packet import packet
from ryu.lib.packet import ethernet, ether_types

from ryu.topology.api import get_switch, get_link
from ryu.topology import event
import networkx as nx
from threading import Timer
from datetime import datetime
import random

NETWORK_STATE_UPDATE_DURATION = 120
NETWORK_STATE_FILE_PATH = "network_state/"
log = Logger().getlogger(__name__)


class ProjectController(app_manager.RyuApp):
    OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]

    def __init__(self, *args, **kwargs):
        super(ProjectController, self).__init__(*args, **kwargs)
        self.mac_to_port = {}
        self.topology_api_app = self
        self.net = nx.DiGraph()
        log.info(nx.__version__)
        self.nodes = {}
        self.links = {}
        self.no_of_nodes = 0
        self.no_of_links = 0
        self.i = 0
        self.update_network_weights()

    # Handy function that lists all attributes in the given object
    def ls(self, obj):
        log.info("\n".join([x for x in dir(obj) if x[0] != "_"]))

    # method to add flow entry in switch
    def add_flow(self, datapath, in_port, dst, actions):
        ofproto = datapath.ofproto

        match = datapath.ofproto_parser.OFPMatch(
            in_port=in_port, dl_dst=haddr_to_bin(dst))

        mod = datapath.ofproto_parser.OFPFlowMod(
            datapath=datapath, match=match, cookie=0,
            command=ofproto.OFPFC_ADD, idle_timeout=0, hard_timeout=0,
            priority=ofproto.OFP_DEFAULT_PRIORITY,
            flags=ofproto.OFPFF_SEND_FLOW_REM, actions=actions)
        datapath.send_msg(mod)

    # method to handle packet in event
    @set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def _packet_in_handler(self, ev):
        msg = ev.msg
        datapath = msg.datapath
        ofproto = datapath.ofproto

        pkt = packet.Packet(msg.data)
        eth = pkt.get_protocol(ethernet.ethernet)

        if eth.ethertype == ether_types.ETH_TYPE_LLDP:
            return

        dst = eth.dst
        src = eth.src
        dpid = datapath.id
        in_port = msg.in_port

        self.mac_to_port.setdefault(dpid, {})
        if src not in self.net:
            self.net.add_node(src)
            self.net.add_edge(src, dpid)
            self.net.add_edge(dpid, src, port=in_port)

        try:
            if dst in self.net:
                path = nx.shortest_path(self.net, src, dst)
                next = path[path.index(dpid) + 1]
                out_port = self.net[dpid][next]['port']
            else:
                out_port = ofproto.OFPP_FLOOD
        except:
            return

        actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]

        if out_port != ofproto.OFPP_FLOOD:
            self.add_flow(datapath, in_port, dst, actions)

        out = datapath.ofproto_parser.OFPPacketOut(
            datapath=datapath, buffer_id=msg.buffer_id, in_port=in_port,
            actions=actions)
        datapath.send_msg(out)

    @set_ev_cls(event.EventSwitchEnter)
    def get_topology_data(self, ev):
        switch_list = get_switch(self.topology_api_app, None)
        switches = [switch.dp.id for switch in switch_list]
        self.net.add_nodes_from(switches)

        links_list = get_link(self.topology_api_app, None)
        # print links_list
        links = [(link.src.dpid, link.dst.dpid, {'port': link.src.port_no}) for link in links_list]
        # print links
        self.net.add_edges_from(links)
        links = [(link.dst.dpid, link.src.dpid, {'port': link.dst.port_no}) for link in links_list]
        # links
        self.net.add_edges_from(links)
        log.info("**********List of links")
        log.info(self.net.edges())

    def remove_node(self, node):
        self.net.remove_node(node)

    def store_network_state(self):
        file_path = NETWORK_STATE_FILE_PATH + datetime.utcnow().strftime('%s') + ".gexf"
        nx.write_gexf(self.net, file_path)

    # method to periodicaly update network state
    def update_network_weights(self):
        Timer(NETWORK_STATE_UPDATE_DURATION, self.update_network_weights).start()
        edges = self.net.edges(data=True)
        # log.info("list of edges")
        # log.info(list(edges))
        for e in edges:
            self.net[e[0]][e[1]]['weight'] = random.randint(1, 10)
        # log.info('updated weight : ' + str(e[0]) + " -> " + str(e[1]) + " : " + str(self.net[e[0]][e[1]]['weight']))

        self.store_network_state()