如何写一个floodlight模块

warjiang

[译]如何写一个floodlight模块

目标

这里完成一个floodligth模块,这个模块可以监听新的MAC地址,并且打印出新的MAC地址以及发现这些MAC地址的交换机的DPID信息.

事前准备

  • 已经装好floodlight,并且把floodlight导入到eclipse中

  • 已经安装了mininet或者是物理ovs交换机

创建一个listener

在eclipse中增加一个类

  1. 在eclipse项目中增加一个package,叫做net.floodlightcontroller.mactracker

  2. 在这个package下增加一个类,叫做MACTracker

  3. MACTracker需要实现IOFMessageListener, IFloodlightModule两个接口,创建好MACTracker类之后,我们在eclipse中会得到如下代码:

package net.floodlightcontroller.mactracker;
 
import java.util.Collection;
import java.util.Map;
 
import org.projectfloodlight.openflow.protocol.OFMessage;
import org.projectfloodlight.openflow.protocol.OFType;
import org.projectfloodlight.openflow.types.MacAddress;
 
import net.floodlightcontroller.core.FloodlightContext;
import net.floodlightcontroller.core.IOFMessageListener;
import net.floodlightcontroller.core.IOFSwitch;
import net.floodlightcontroller.core.module.FloodlightModuleContext;
import net.floodlightcontroller.core.module.FloodlightModuleException;
import net.floodlightcontroller.core.module.IFloodlightModule;
import net.floodlightcontroller.core.module.IFloodlightService;
 
public class MACTracker implements IOFMessageListener, IFloodlightModule {
 
    @Override
    public String getName() {
        // TODO Auto-generated method stub
        return null;
    }
 
    @Override
    public boolean isCallbackOrderingPrereq(OFType type, String name) {
        // TODO Auto-generated method stub
        return false;
    }
 
    @Override
    public boolean isCallbackOrderingPostreq(OFType type, String name) {
        // TODO Auto-generated method stub
        return false;
    }
 
    @Override
    public Collection<Class<? extends IFloodlightService>> getModuleServices() {
        // TODO Auto-generated method stub
        return null;
    }
 
    @Override
    public Map<Class<? extends IFloodlightService>, IFloodlightService> getServiceImpls() {
        // TODO Auto-generated method stub
        return null;
    }
 
    @Override
    public Collection<Class<? extends IFloodlightService>> getModuleDependencies() {
        // TODO Auto-generated method stub
        return null;
    }
 
    @Override
    public void init(FloodlightModuleContext context)
            throws FloodlightModuleException {
        // TODO Auto-generated method stub
 
    }
 
    @Override
    public void startUp(FloodlightModuleContext context) {
        // TODO Auto-generated method stub
 
    }
 
    @Override
    public Command receive(IOFSwitch sw, OFMessage msg, FloodlightContext cntx) {
        // TODO Auto-generated method stub
        return null;
    }
 
}

设置模块的依赖和初始化函数

下面往MACTracker这个类中增加三个成员变量,如下

protected IFloodlightProviderService floodlightProvider;
protected Set<Long> macAddresses;
protected static Logger logger;

为了监听OpenFlow消息,所以需要一个FloodlightProvider(IFloodlightProviderService class)对象.
为了保存当前发现的mac地址,需要一个set对象来保存mac地址。
为了显示日志信息,打印mac地址以及交换机的信息,所以需要要给Logger对象
下面我们在getModuleDependencies函数中告诉floodlight,我们需要依赖那些模块。代码如下:

@Override
public Collection<Class<? extends IFloodlightService>> getModuleDependencies() {
    Collection<Class<? extends IFloodlightService>> l = new ArrayList<Class<? extends IFloodlightService>>();
    l.add(IFloodlightProviderService.class);
    return l;
}

下面修改init函数,init函数在startup函数之前被调用。init函数的作用是加载依赖项以及初始化成员变量。如下:

@Override
public void init(FloodlightModuleContext context) throws FloodlightModuleException {
    floodlightProvider = context.getServiceImpl(IFloodlightProviderService.class);
    macAddresses = new ConcurrentSkipListSet<Long>();
    logger = LoggerFactory.getLogger(MACTracker.class);
}

处理Packet-In消息

下面来实现基本监听功能。首先在startUp函数中注册PACKET_IN消息的处理,负责处理的对象就是this,也就是MacTracerk。这边在startUp中,可以保证所有的依赖项都已经加载完毕。

@Override
public void startUp(FloodlightModuleContext context) {
    floodlightProvider.addOFMessageListener(OFType.PACKET_IN, this);
}

对与这个OFMessage监听器,我们也给他起个名字,覆盖父类的getName函数,如下:

@Override
public String getName() {
    return MACTracker.class.getSimpleName();
}

下面来实现具体的处理逻辑


@Override
   public net.floodlightcontroller.core.IListener.Command receive(IOFSwitch sw, OFMessage msg, FloodlightContext cntx) {
        Ethernet eth = IFloodlightProviderService.bcStore.get(cntx, IFloodlightProviderService.CONTEXT_PI_PAYLOAD);
 
        Long sourceMACHash = eth.getSourceMACAddress().getLong();
        if (!macAddresses.contains(sourceMACHash)) {
            macAddresses.add(sourceMACHash);
            logger.info("MAC Address: {} seen on switch: {}",
                    eth.getSourceMACAddress().toString(),
                    sw.getId().toString());
        }
        return Command.CONTINUE;
    }

处理完成之后,为了让后续的流程可以继续处理OFMessage,我们需要return一个Command.CONTINUE;

注册模块

  1. 首先告诉floodlight我们的模块存在
    修改 src/main/resources/META-INF/services/net.floodlightcontroller.core.modul文件,在结尾增加包名net.floodlightcontroller.mactracker.MACTracker。如图

  2. 告诉floodlight启动的时候,把我们的模块启动起来。修改src/main/resources/floodlightdefault.properties,增加类名net.floodlightcontroller.mactracker.MACTracker,如图所示:

这样新的模块就已经完成。

把mininet连接到floodlight上

  1. 启动floodlight

  2. 启动mininetsudo mn --controller=remote,ip=127.0.0.1,port=6653.执行pingall,在eclipse控制台中可以看到打印的信息,如图:

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