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RyuBook1.0案例三:REST Linkage

2019-05-14来源:ju111.net

REST Linkage

该小结主要介绍如何添加一个REST Link 函数

RYU本身提供了一个类似WSGI的web服务器功能。借助这个功能,我们可以创建一个REST API。基于创建的REST API,可以快速的将RYU系统与其他系统或者是浏览器相连接,非常实用的一个功能。

程序解析

在案例中,实现了两个类

SimpleSwitchRest13继承SimpleSwitch13的功能,即具备父类的三层交换机的基本功能。注册WSGI服务配置mac_to_portSimpleSwitchControllerREST API功能实现的主体类返回指定交换机的mac_table更新指定的mac_table条目

SimpleSwitchRest13类实现

_CONTEXTS = {"wsgi": WSGIApplication}

该成员变量用于指明Ryu的兼容WSGI的web服务对象。

wsgi = kwargs["wsgi"]wsgi.register(SimpleSwitchController, {simple_switch_instance_name: self})

通过上一步设置的_CONTEXTS成员变量,可以通过kwargs进行实例化一个WSGIApplication。同时使用register方法注册该服务到controller类上。

@set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)def switch_features_handler(self, ev): super(SimpleSwitchRest13, self).switch_features_handler(ev) datapath = ev.msg.datapath self.switches[datapath.id] = datapath self.mac_to_port.setdefault(datapath.id, {})

重写父类的switch_features_handler函数

存储datapath到switches初始化MAC 地址表

def set_mac_to_port(self, dpid, entry): # 获取MAC table mac_table = self.mac_to_port.setdefault(dpid, {}) # 获取datapath,如果为None,证明没有该交换机 datapath = self.switches.get(dpid) entry_port = entry["port"] entry_mac = entry["mac"] if datapath is not None: parser = datapath.ofproto_parser # 如果entry_port不在mac_table中 if entry_port not in mac_table.values(): # 下发流表 for mac, port in mac_table.items(): # from known device to new device actions = [parser.OFPActionOutput(entry_port)] match = parser.OFPMatch(in_port=port, eth_dst=entry_mac) self.add_flow(datapath, 1, match, actions) # from new device to known device actions = [parser.OFPActionOutput(port)] match = parser.OFPMatch(in_port=entry_port, eth_dst=mac) self.add_flow(datapath, 1, match, actions) # 添加entry_mac, entry_port到mac_table mac_table.update({entry_mac: entry_port}) return mac_table

该方法将MAC地址和端口注册到指定的交换机。该方法主要被REST API的PUT方法所调用。

SimpleSwitchController类实现

@route("simpleswitch", url, methods=["GET"], requirements={"dpid": dpid_lib.DPID_PATTERN})

借助route装饰器关联方法和URL。参数如下:

第一个参数:任何自定义名称第二个参数:指明URL第三个参数:指定http方法第四个参数:指明指定位置的格式,URL(/simpleswitch/mactable/{dpid} 匹配DPID_PATTERN的描述

当使用GET方式访问到该REST API接口时,调用list_mac_table函数

def list_mac_table(self, req, **kwargs): simple_switch = self.simple_switch_app # 获取{dpid} dpid = dpid_lib.str_to_dpid(kwargs["dpid"]) # 如果没有dpid,返回404 if dpid not in simple_switch.mac_to_port: return Response(status=404) # 获取mac_table mac_table = simple_switch.mac_to_port.get(dpid, {}) body = json.dumps(mac_table) return Response(content_type="application/json", body=body)

# 使用PUT方式设置mac_table@route("simpleswitch", url, methods=["PUT"], requirements={"dpid": dpid_lib.DPID_PATTERN}) def put_mac_table(self, req, **kwargs): simple_switch = self.simple_switch_app dpid = dpid_lib.str_to_dpid(kwargs["dpid"]) try: new_entry = req.json if req.body else {} except ValueError: raise Response(status=400) if dpid not in simple_switch.mac_to_port: return Response(status=404) try: mac_table = simple_switch.set_mac_to_port(dpid, new_entry) body = json.dumps(mac_table) return Response(content_type="application/json", body=body) except Exception as e: return Response(status=500)

运行分析

启动mininet创建网络拓扑图

sudo mn --topo single,3 --mac --switch ovsk,protocols=OpenFlow13 --controller remote -x

启动控制器程序,打印log信息如下:

debugging is available (--enable-debugger option is turned on)loading app SimpleSwitchRest13loading app ryu.controller.ofp_handlercreating context wsgiinstantiating app SimpleSwitchRest13 of SimpleSwitchRest13instantiating app ryu.controller.ofp_handler of OFPHandlerBRICK SimpleSwitchRest13 CONSUMES EventOFPPacketIn CONSUMES EventOFPSwitchFeaturesBRICK ofp_event PROVIDES EventOFPPacketIn TO {"SimpleSwitchRest13": set(["main"])} PROVIDES EventOFPSwitchFeatures TO {"SimpleSwitchRest13": set(["config"])} CONSUMES EventOFPEchoReply CONSUMES EventOFPSwitchFeatures CONSUMES EventOFPPortDescStatsReply CONSUMES EventOFPHello CONSUMES EventOFPErrorMsg CONSUMES EventOFPEchoRequest CONSUMES EventOFPPortStatus(22238) wsgi starting up on http://0.0.0.0:8080

这里我们可以看到,wsgi服务已经启动,端口号为8080

查询s1的默认MAC table

curl -X GET http://127.0.0.1:8080/simpleswitch/mactable/0000000000000001

返回为{}

在mininet中执行

mininet> h1 ping -c 1 h2

log信息打印如下信息:

EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:01 ff:ff:ff:ff:ff:ff 1EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:02 00:00:00:00:00:01 2EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:01 00:00:00:00:00:02 1

返回了三条PackageIn消息(ARP过程)

    host1发起的ARP请求,并广播host2发起的ARP请求,MAC地址是host1ICMP echo reply request 从host1 发生到host2

此刻按照设计,已经添加了两条条目到MAC table,再次查询进行验证。

curl -X GET http://127.0.0.1:8080/simpleswitch/mactable/0000000000000001

返回如下,证明符合实验预期:

{"00:00:00:00:00:02": 2, "00:00:00:00:00:01": 1}

测试POST API接口,添加h3到MAC Table

curl -X PUT -d "{"mac" : "00:00:00:00:00:03", "port" : 3}" http://127.0.0.1:8080/simpleswitch/mactable/0000000000000001

返回:

{"00:00:00:00:00:03": 3, "00:00:00:00:00:02": 2, "00:00:00:00:00:01": 1}

证明h3 mac已经被添加到MAC table。因为h3已经被添加到MAC Table中,所以理论上当h1 ping h3时将不再通过ARP查找到h3.

测试:在mininet中执行命令

mininet> h1 ping c1 h3PING 10.0.0.3 (10.0.0.3) 56(84) bytes of data.64 bytes from 10.0.0.3: icmp_seq=1 ttl=64 time=2.48 ms--- 10.0.0.3 ping statistics ---1 packets transmitted, 1 received, 0% packet loss, time 0msrtt min/avg/max/mdev = 2.480/2.480/2.480/0.000 ms

控制器log信息如下:

EVENT ofp_event->SimpleSwitchRest13 EventOFPPacketInpacket in 1 00:00:00:00:00:01 ff:ff:ff:ff:ff:ff 1

我们可以看到,只有h1在不知道h3地址的情况下,发起ARP广播,将PackageIn消息发送到控制器,而不再出现以后的一系列消息。这证明MAC Table中添加的条目成功生效,符合预期情况。