2019 SDN上機第5次做業

1.瀏覽RYU官網學習RYU控制器的安裝和RYU開發入門教程，提交你對於教程代碼的理解，包括但不限於：

描述官方教程實現了一個什麼樣的交換機功能？

能夠將收到的數據包轉發給全部端口

控制器設定交換機支持什麼版本的OpenFlow？

OpenFlow v1.0

控制器設定了交換機如何處理數據包？

@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
    def packet_in_handler(self, ev):
        msg = ev.msg
        dp = msg.datapath
        ofp = dp.ofproto
        ofp_parser = dp.ofproto_parser
        actions = [ofp_parser.OFPActionOutput(ofp.OFPP_FLOOD)]
        out = ofp_parser.OFPPacketOut(
            datapath=dp, buffer_id=msg.buffer_id,in_port=msg.in_port,
            actions=actions)
        dp.send_msg(out)

如上方代碼所示，新方法'packet_in_handler'已添加到L2Switch類。當Ryu收到OpenFlow packet_in消息時，將調用此方法。訣竅是「 set_ev_cls」裝飾器。該裝飾器告訴Ryu什麼時候應調用裝飾的函數。裝飾器的第一個參數指示應調用此函數的事件類型；第二個參數指示開關的狀態。

在packet_in_handler函數的前半部分：

• ev.msg是表示packet_in數據結構的對象；
• msg.dp是表明數據路徑（開關）的對象；
• dp.ofproto和dp.ofproto_parser是表明Ryu和交換機協商的OpenFlow協議的對象；

在packet_in_handler函數的後半部分：

• OFPActionOutput類與packet_out消息一塊兒使用，以指定要從中發送數據包的交換機端口。該應用程序使用OFPP_FLOOD標誌來指示應在全部端口上發送數據包；
• OFPPacketOut類用於構建packet_out消息；
• 若是使用OpenFlow消息類對象調用Datapath類的send_msg方法，則Ryu會生成聯機數據格式並將其發送到交換機。

2.根據官方教程和提供的示例代碼（SimpleSwitch.py），將具備自學習功能的交換機代碼（SelfLearning.py）補充完整

from ryu.base import app_manager
from ryu.controller import ofp_event
from ryu.controller.handler import MAIN_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
from ryu.lib.packet import ether_types


class SimpleSwitch(app_manager.RyuApp):
    # TODO define OpenFlow 1.0 version for the switch
    # add your code here
    OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]

    def __init__(self, *args, **kwargs):
        super(SimpleSwitch, self).__init__(*args, **kwargs)
        self.mac_to_port = {}
    
    
    def add_flow(self, datapath, in_port, dst, src, actions):
        ofproto = datapath.ofproto

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

        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)
        # TODO send modified message out
        # add your code here
        datapath.send_msg(mod)

    @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:
            # ignore lldp packet
            return
        if eth.ethertype == ether_types.ETH_TYPE_IPV6:
            # ignore ipv6 packet
            return       
        
        dst = eth.dst
        src = eth.src
        dpid = datapath.id
        self.mac_to_port.setdefault(dpid, {})

        self.logger.info("packet in DPID:%s MAC_SRC:%s MAC_DST:%s IN_PORT:%s", dpid, src, dst, msg.in_port)

        # learn a mac address to avoid FLOOD next time.
        self.mac_to_port[dpid][src] = msg.in_port

        if dst in self.mac_to_port[dpid]:
            out_port = self.mac_to_port[dpid][dst]
        else:
            out_port = ofproto.OFPP_FLOOD

        # TODO define the action for output
        # add your code here
        actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]

        # install a flow to avoid packet_in next time
        if out_port != ofproto.OFPP_FLOOD:
            self.logger.info("add flow s:DPID:%s Match:[ MAC_SRC:%s MAC_DST:%s IN_PORT:%s ], Action:[OUT_PUT:%s] ", dpid, src, dst, msg.in_port, out_port)
            self.add_flow(datapath, msg.in_port, dst, src, actions)

        data = None
        if msg.buffer_id == ofproto.OFP_NO_BUFFER:
            data = msg.data
        

        # TODO define the OpenFlow Packet Out
        # add your code here
        out = datapath.ofproto_parser.OFPPacketOut(
      datapath=datapath, 
      buffer_id=msg.buffer_id, 
      in_port=msg.in_port,
      actions=actions, data=data)
  datapath.send_msg(out)

    print ("PACKET_OUT...")