TraceCode org.onosproject.fwd

Hello!

這次ㄧ樣來追一下程式碼，當作課堂的筆記。這堂課是交通大學的軟體定義網路，蠻有趣的一堂課。

這次主要想追的程式碼是onos中fwd這個app裡的ReactiveForwarding.java這個檔案。有些偷懶的就直接把function的用途寫在上面，不一行行寫註解了。甚至有些作業用不到的function，就直接不寫了，因為這篇還沒打完作業就寫完了，有點懶得繼續下去XDD

Code

完整的code可以看這裡

/**
* Sample reactive forwarding application.
*/
@Component(immediate = true)
@Service(value = ReactiveForwarding.class)
public class ReactiveForwarding {
  private static final int DEFAULT_TIMEOUT = 10;
  private static final int DEFAULT_PRIORITY = 10;
  private final Logger log = getLogger(getClass());
  //用於提供網絡拓補信息
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected TopologyService topologyService;
  
  //攔截封包，選擇要攔截哪些封包，或是做哪些動作 
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected PacketService packetService;
  //用於與終端主機交互
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected HostService hostService;
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected FlowRuleService flowRuleService;
  //用於新增flow rule
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected FlowObjectiveService flowObjectiveService;
  //在使用onos的各種服務前，要先向CoreService註冊
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected CoreService coreService;
  //追蹤整個系統各個組件的配置
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected ComponentConfigService cfgService;
  @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
  protected StorageService storageService;
  //封包進來的時候，進行處理的handler
  private ReactivePacketProcessor processor = new        ReactivePacketProcessor();
  //metrics:記錄所有host的資訊
  private  EventuallyConsistentMap<MacAddress, ReactiveForwardMetrics> metrics;
  //ONOS下，每個app都要有自己的appId
  private ApplicationId appId;
  //一些設定
  @Property(name = "packetOutOnly", boolValue = false,
    label = "Enable packet-out only forwarding; default is false")
  private boolean packetOutOnly = false;
  @Property(name = "packetOutOfppTable", boolValue = false,
    label = "Enable first packet forwarding using OFPP_TABLE port " +"instead of PacketOut with actual port; default is false")
  private boolean packetOutOfppTable = false;
  .
  .
  .
  //Entity capable of receiving network topology related events
  private final TopologyListener topologyListener = new     InternalTopologyListener();
  private ExecutorService blackHoleExecutor;
  //@Activate - marks a method as the method to call during the component startup routine.
  @Activate
  public void activate(ComponentContext context) {
    //一個快速高效的反序列化框架
    KryoNamespace.Builder metricSerializer = KryoNamespace.newBuilder()
      .register(KryoNamespaces.API)
      .register(ReactiveForwardMetrics.class)
      .register(MultiValuedTimestamp.class);
    metrics =  storageService.<MacAddress,    ReactiveForwardMetrics>eventuallyConsistentMapBuilder()
      .withName("metrics-fwd")
      .withSerializer(metricSerializer)
      .withTimestampProvider((key, metricsData) -> new
    MultiValuedTimestamp<>(new WallClockTimestamp(), System.nanoTime()))
      .build();
    //topology有改變的話，就可以call(?)
    blackHoleExecutor =  newSingleThreadExecutor(groupedThreads("onos/app/fwd",
      "black-hole-fixer",
      log));
    //追蹤整個系統各個組件的配置
    cfgService.registerProperties(getClass());
    //註冊appId
    appId = coreService.registerApplication("org.onosproject.fwd");
    //ReactivePacketProcessor(這裡的變數是processor).process裡定義了接收到封包要做什麼動作
    packetService.addProcessor(processor, PacketProcessor.director(2));

    //當拓墣改變的話，會呼叫
    topologyService.addListener(topologyListener);
    //In this way the application components can continue to use the standard and well-understood OSGi configuration via ComponentContext.
    readComponentConfiguration(context);
    //想要攔截哪些種類的封包
    requestIntercepts();
    log.info("Started", appId.id());
  }
  /** 
  * Request packet in via packet service.
  *
  * 在擷取的時候，指定想要擷取哪些封包
  */
  private void requestIntercepts() {
    //Abstraction of a slice of network traffic.
    //Builder of traffic selector entities.
    TrafficSelector.Builder selector = DefaultTrafficSelector.builder();
    selector.matchEthType(Ethernet.TYPE_IPV4);
 
    //要求讓ipv4的封包都packet in進來    
    packetService.requestPackets(selector.build(), PacketPriority.REACTIVE, appId);
    
    selector.matchEthType(Ethernet.TYPE_IPV6);
    if (ipv6Forwarding) {
      packetService.requestPackets(selector.build(),  
PacketPriority.REACTIVE, appId);
    } else {
      packetService.cancelPackets(selector.build(),     PacketPriority.REACTIVE, appId);
    }
  }
  
  /**
   * Cancel request for packet in via packet service.
   * 反正就是做跟requestIntercepts相反的事情
   */
  private void withdrawIntercepts() {
    TrafficSelector.Builder selector = DefaultTrafficSelector.builder();
 
   selector.matchEthType(Ethernet.TYPE_IPV4);
    packetService.cancelPackets(selector.build(),
      PacketPriority.REACTIVE, appId);
    selector.matchEthType(Ethernet.TYPE_IPV6);
    packetService.cancelPackets(selector.build(),   
PacketPriority.REACTIVE, appId);
  }
  /**
   * Extracts properties from the component configuration context.
   *
   * 把一些設定從context裡面抽取出來
   * @param context the component context
   */
   private void readComponentConfiguration(ComponentContext context
   {
   }
  /**
  * Packet processor responsible for forwarding packets along their paths.
  * 這個function來決定要怎麼轉送封包
  */
  private class ReactivePacketProcessor implements PacketProcessor {
  //修改父母類別的function
    @Override
    public void process(PacketContext context) {
    }
  } 
  // 判斷是不是 control packet(LLDP, BDDP)
  // Indicates whether this is a control packet, e.g. LLDP, BDDP
  private boolean isControlPacket(Ethernet eth) {
    short type = eth.getEtherType();
    return type == Ethernet.TYPE_LLDP || type == Ethernet.TYPE_BSN;
  }
  // 假如目前的點可以flood，那就flood
  // Floods the specified packet if permissible.
  private void flood(PacketContext context, ReactiveForwardMetrics macMetrics) {
     if(topologyService.isBroadcastPoint(topologyService.currentTopology(),context.inPacket().receivedFrom())) {
      packetOut(context, PortNumber.FLOOD, macMetrics);
    } else {
      context.block();
    }
  }
  // Sends a packet out the specified port.
  // 送出封包到指定的port
  private void packetOut(PacketContext context, PortNumber portNumber, ReactiveForwardMetrics macMetrics) {
  }

  // Install a rule forwarding the packet to the specified port.
  // 1.packetout, 2.flow_mod
  // flow_mod之後要packetout，這樣才不會把封包給平白無故地丟掉
  private void installRule(PacketContext context, PortNumber portNumber, ReactiveForwardMetrics macMetrics) {
  }

Reference

[1]开发基于ONOS的SDN应用程序 http://sdnhub.cn/index.php/onos-application-tutorial/
[2]onos wiki https://wiki.onosproject.org/display/ONOS11/Application+tutorial
[3]Kryo https://baymaxhuang.github.io/2017/06/14/Kryo%E5%BA%8F%E5%88%97%E5%8C%96%E5%8F%8A%E5%85%B6%E5%9C%A8ONOS%E4%B8%AD%E7%9A%84%E5%BA%94%E7%94%A8/
[4]storageService https://baymaxhuang.github.io/2017/02/15/ONOS-cluster%E5%88%86%E5%B8%83%E5%BC%8F%E6%95%B0%E6%8D%AE%E5%AD%98%E5%82%A8%E5%92%8C%E4%B8%9C%E8%A5%BF%E5%90%91%E9%80%9A%E4%BF%A1/
[5]onos api http://api.onosproject.org/1.5.0/overview-summary.html
[6]ONOS源碼筆記 — 前提 https://www.twblogs.net/a/5b8a41992b71775d1ce63797
[7]newSingleThreadExecutor https://blog.csdn.net/guyuealian/article/details/51706310
[8]ONOS源码笔记 — 机制 https://blog.csdn.net/fanshuquan/article/details/51251223
[9]path http://api.onosproject.org/1.5.1/org/onosproject/net/Path.html
[10]reactive forwarding http://networkstatic.net/openflow-proactive-vs-reactive-flows/
[11]how to flow mod? https://groups.google.com/a/onosproject.org/forum/#!topic/onos-dev/5o-6kDYby6I
[12]learning-sdn https://github.com/OSE-Lab/Learning-SDN/tree/master/Controller/ONOS