python - ryu在流添加后通过交换机处理数据包
我正在使用一个用Python写的Ryu开放流控制器，来监控我虚拟的mininet中的数据包。我有3个主机，我正在阻止主机2和主机3之间的通信，以及主机3和主机2之间的通信。其他的数据包会被添加到交换机的流表中。
我的问题是，当一个流被添加后，如果有两个主机之间的数据包符合流表中的规则，我的事件就不会被触发。
举个例子，如果交换机看到从主机1到主机2的数据包，这是合法的，所以这个流会被添加到表中。但是如果再发送一个从主机1到主机2的数据包，它就不会再次经过这个方法。我查阅了Ryu的指南，但没有找到关于流已经被添加到交换机流表时的情况。
我该如何捕捉这些数据包呢？
谢谢！
这是我的代码：
import logging
import struct
from ryu.base import app_manager
from ryu.controller import mac_to_port
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_str
class SimpleSwitch(app_manager.RyuApp):
OFP_VERSIONS = [ofproto_v1_0.OFP_VERSION]
counterTraffic=0
def __init__(self, *args, **kwargs):
super(SimpleSwitch, self).__init__(*args, **kwargs)
self.mac_to_port = {}
def add_flow(self, datapath, in_port, dst, actions):
ofproto = datapath.ofproto
wildcards = ofproto_v1_0.OFPFW_ALL
wildcards &= ~ofproto_v1_0.OFPFW_IN_PORT
wildcards &= ~ofproto_v1_0.OFPFW_DL_DST
match = datapath.ofproto_parser.OFPMatch(
wildcards, in_port, 0, dst,
0, 0, 0, 0, 0, 0, 0, 0, 0)
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)
@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
def _packet_in_handler(self, ev):
print("Im in main function")
msg = ev.msg
datapath = msg.datapath
ofproto = datapath.ofproto
dst, src, _eth_type = struct.unpack_from('!6s6sH', buffer(msg.data), 0)
dpid = datapath.id
self.mac_to_port.setdefault(dpid, {})
self.logger.info("packet in %s %s %s %s",
dpid, haddr_to_str(src), haddr_to_str(dst),
msg.in_port)
if (haddr_to_str(dst) == "00:00:00:00:00:01"):
print "dst"
self.counterTraffic +=1
if not ((haddr_to_str(src) == "00:00:00:00:00:02" and haddr_to_str(dst) =="00:00:00:00:00:03")or (haddr_to_str(src) == "00:00:00:00:00:03" and haddr_to_str(dst) =="00:00:00:00:00:02")):
# learn a mac address to avoid FLOOD next time.
print("after condition")
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
actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]
# install a flow to avoid packet_in next time
if out_port != ofproto.OFPP_FLOOD:
self.add_flow(datapath, msg.in_port, dst, actions)
out = datapath.ofproto_parser.OFPPacketOut(
datapath=datapath, buffer_id=msg.buffer_id, in_port=msg.in_port,
actions=actions)
datapath.send_msg(out)
if (haddr_to_str(src) == "00:00:00:00:00:01"):
print "src"
self.counterTraffic +=1
print(self.counterTraffic)
@set_ev_cls(ofp_event.EventOFPPortStatus, MAIN_DISPATCHER)
def _port_status_handler(self, ev):
msg = ev.msg
reason = msg.reason
port_no = msg.desc.port_no
ofproto = msg.datapath.ofproto
if reason == ofproto.OFPPR_ADD:
self.logger.info("port added %s", port_no)
elif reason == ofproto.OFPPR_DELETE:
self.logger.info("port deleted %s", port_no)
elif reason == ofproto.OFPPR_MODIFY:
self.logger.info("port modified %s", port_no)
else:
self.logger.info("Illeagal port state %s %s", port_no, reason)
1 个回答
1
我尝试打印 haddr_to_str(src) 和 haddr_to_str(dst)，结果得到了 00:00:00:00:00:03 和 ff:ff:ff:ff:ff:ff，这和我预期的不一样。我想要的是源地址 2 和目标地址 3。
简单来说，你正确解码了目标的 MAC 地址……但是，IP 地址需要通过 ARP 来解析 MAC 地址，这就是你看到 ff:ff:ff:ff:ff:ff 的原因……这些只是 ryu 控制器 中的 ARP 帧。
我构建了一个完整的控制器，可以解码到下面的 IPv4 层……
更新的 ryu 交换机数据包解码器
你一直在解码原始的 structs，但其实使用 ryu Packet 库 会简单得多，而不是去拆解原始的 struct 数据包。这是我对 _packet_in_handler() 的快速替换，它会打印出源和目标的 MAC 地址，以及上层协议……
from ryu.lib.packet import packet, ethernet, arp, ipv4
import array
@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
def _packet_in_handler(self, ev):
### Mike Pennington's logging modifications
## Set up to receive the ethernet src / dst addresses
pkt = packet.Packet(array.array('B', ev.msg.data))
eth_pkt = pkt.get_protocol(ethernet.ethernet)
arp_pkt = pkt.get_protocol(arp.arp)
ip4_pkt = pkt.get_protocol(ipv4.ipv4)
if arp_pkt:
pak = arp_pkt
elif ip4_pkt:
pak = ip4_pkt
else:
pak = eth_pkt
self.logger.info(' _packet_in_handler: src_mac -> %s' % eth_pkt.src)
self.logger.info(' _packet_in_handler: dst_mac -> %s' % eth_pkt.dst)
self.logger.info(' _packet_in_handler: %s' % pak)
self.logger.info(' ------')
src = eth_pkt.src # Set up the src and dst variables so you can use them
dst = eth_pkt.dst
## Mike Pennington's modifications end here
msg = ev.msg
datapath = msg.datapath
ofproto = datapath.ofproto
dpid = datapath.id
self.mac_to_port.setdefault(dpid, {})
# 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
actions = [datapath.ofproto_parser.OFPActionOutput(out_port)]
# install a flow to avoid packet_in next time
if out_port != ofproto.OFPP_FLOOD:
self.add_flow(datapath, msg.in_port, dst, actions)
out = datapath.ofproto_parser.OFPPacketOut(
datapath=datapath, buffer_id=msg.buffer_id, in_port=msg.in_port,
actions=actions)
datapath.send_msg(out)
现在，每当发送以太网数据包时，你会在 mininet 会话中看到这些……
_packet_in_handler: src_mac -> 00:00:00:00:00:03
_packet_in_handler: dst_mac -> 33:33:00:00:00:02
_packet_in_handler: ethernet(dst='33:33:00:00:00:02',ethertype=34525,src='00:00:00:00:00:03')
------
ARP 数据包看起来是这样的……
_packet_in_handler: src_mac -> 00:00:00:00:00:01
_packet_in_handler: dst_mac -> ff:ff:ff:ff:ff:ff
_packet_in_handler: arp(dst_ip='10.0.0.2',dst_mac='00:00:00:00:00:00',hlen=6,hwtype=1,opcode=1,plen=4,proto=2048,src_ip='10.0.0.1',src_mac='00:00:00:00:00:01')
------
演示
假设我把上面的修改代码（包括你源代码的其他部分）保存为 ne_question.py。
root@mininet-vm:/home/mininet# ryu-manager ne_question.py &
[1] 14073
loading app ne_question.py
loading app ryu.controller.ofp_handler
instantiating app ryu.controller.ofp_handler of OFPHandler
instantiating app ne_question.py of SimpleSwitch
root@mininet-vm:/home/mininet#
- 接下来，我构建了交换机拓扑，正如你在评论中提到的那样。
root@mininet-vm:/home/mininet# mn --topo single,3 --mac --switch ovsk --controller remote
*** Creating network
*** Adding controller
*** Adding hosts:
h1 h2 h3
*** Adding switches:
s1
*** Adding links:
(h1, s1) (h2, s1) (h3, s1)
*** Configuring hosts
h1 h2 h3
*** Starting controller
*** Starting 1 switches
s1
*** Starting CLI:
mininet> _packet_in_handler: src_mac -> 00:00:00:00:00:02
_packet_in_handler: dst_mac -> 33:33:00:00:00:02
_packet_in_handler: ethernet(dst='33:33:00:00:00:02',ethertype=34525,src='00:00:00:00:00:02')
------
_packet_in_handler: src_mac -> 00:00:00:00:00:01
_packet_in_handler: dst_mac -> 33:33:00:00:00:02
_packet_in_handler: ethernet(dst='33:33:00:00:00:02',ethertype=34525,src='00:00:00:00:00:01')
------
_packet_in_handler: src_mac -> 00:00:00:00:00:03
_packet_in_handler: dst_mac -> 33:33:00:00:00:02
_packet_in_handler: ethernet(dst='33:33:00:00:00:02',ethertype=34525,src='00:00:00:00:00:03')
------
- 最后，我运行了网络服务器，并尝试拉取一个页面……注意 ARP 被发送来解析 HTTP GET 的目标地址。ARP 的目标地址是
ff:ff:ff:ff:ff:ff。顺便说一下，如果你把wget改成h2 wget h1，一切都会正常工作……
mininet> h1 python -m SimpleHTTPServer 80 &
mininet> h2 wget -O - h1
--2014-03-28 04:22:25-- http://10.0.0.1/
Connecting to 10.0.0.1:80... _packet_in_handler: src_mac -> 00:00:00:00:00:02
_packet_in_handler: dst_mac -> ff:ff:ff:ff:ff:ff
_packet_in_handler: arp(dst_ip='10.0.0.1',dst_mac='00:00:00:00:00:00',hlen=6,hwtype=1,opcode=1,plen=4,proto=2048,src_ip='10.0.0.2',src_mac='00:00:00:00:00:02')
------
--2014-03-28 04:00:58-- http://10.0.0.1/
Connecting to 10.0.0.1:80... _packet_in_handler: src_mac -> 00:00:00:00:00:02
_packet_in_handler: dst_mac -> 00:00:00:00:00:01
_packet_in_handler: ipv4(csum=33886,dst='10.0.0.1',flags=2,header_length=5,identification=41563,offset=0,option=None,proto=6,src='10.0.0.2',tos=0,total_length=60,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:01
_packet_in_handler: dst_mac -> 00:00:00:00:00:02
_packet_in_handler: ipv4(csum=9914,dst='10.0.0.2',flags=2,header_length=5,identification=0,offset=0,option=None,proto=6,src='10.0.0.1',tos=0,total_length=60,ttl=64,version=4)
------
connected.
HTTP request sent, awaiting response... _packet_in_handler: src_mac -> 00:00:00:00:00:02
_packet_in_handler: dst_mac -> 00:00:00:00:00:01
_packet_in_handler: ipv4(csum=33893,dst='10.0.0.1',flags=2,header_length=5,identification=41564,offset=0,option=None,proto=6,src='10.0.0.2',tos=0,total_length=52,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:02
_packet_in_handler: dst_mac -> 00:00:00:00:00:01
_packet_in_handler: ipv4(csum=33784,dst='10.0.0.1',flags=2,header_length=5,identification=41565,offset=0,option=None,proto=6,src='10.0.0.2',tos=0,total_length=160,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:01
_packet_in_handler: dst_mac -> 00:00:00:00:00:02
_packet_in_handler: ipv4(csum=61034,dst='10.0.0.2',flags=2,header_length=5,identification=14423,offset=0,option=None,proto=6,src='10.0.0.1',tos=0,total_length=52,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:01
_packet_in_handler: dst_mac -> 00:00:00:00:00:02
_packet_in_handler: ipv4(csum=61016,dst='10.0.0.2',flags=2,header_length=5,identification=14424,offset=0,option=None,proto=6,src='10.0.0.1',tos=0,total_length=69,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:01
_packet_in_handler: dst_mac -> 00:00:00:00:00:02
_packet_in_handler: ipv4(csum=60037,dst='10.0.0.2',flags=2,header_length=5,identification=14425,offset=0,option=None,proto=6,src='10.0.0.1',tos=0,total_length=1047,ttl=64,version=4)
------
200 OK
Length: 858 [text/html]
Saving to: `STDOUT'
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html>
<title>Directory listing for /</title>
<body>
<h2>Directory listing for /</h2>
<hr>
<ul>
<li><a href=".bash_history">.bash_history</a>
<li><a href=".bash_logout">.bash_logout</a>
<li><a href=".bashrc">.bashrc</a>
<li><a href=".cache/">.cache/</a>
<li><a href=".gitconfig">.gitconfig</a>
<li><a href=".profile">.profile</a>
<li><a href=".rnd">.rnd</a>
<li><a href=".wireshark/">.wireshark/</a>
<li><a href="install-mininet-vm.sh">install-mininet-vm.sh</a>
<li><a href="mininet/">mininet/</a>
<li><a href="ne_question.py">ne_question.py</a>
<li><a href="ne_question.pyc">ne_question.pyc</a>
<li><a href="of-dissector/">of-dissector/</a>
<li><a href="oflops/">oflops/</a>
<li><a href="oftest/">oftest/</a>
<li><a href="openflow/">openflow/</a>
<li><a href="pox/">pox/</a>
</ul>
<hr>
</body>
</html>
0K 100% 161M=0s
2014-03-28 04:00:58 (161 MB/s) - written to stdout [858/858]
_packet_in_handler: src_mac -> 00:00:00:00:00:02
mininet> _packet_in_handler: dst_mac -> 00:00:00:00:00:01
_packet_in_handler: ipv4(csum=33891,dst='10.0.0.1',flags=2,header_length=5,identification=41566,offset=0,option=None,proto=6,src='10.0.0.2',tos=0,total_length=52,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:02
_packet_in_handler: dst_mac -> 00:00:00:00:00:01
_packet_in_handler: ipv4(csum=33890,dst='10.0.0.1',flags=2,header_length=5,identification=41567,offset=0,option=None,proto=6,src='10.0.0.2',tos=0,total_length=52,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:02
_packet_in_handler: dst_mac -> 00:00:00:00:00:01
_packet_in_handler: ipv4(csum=33889,dst='10.0.0.1',flags=2,header_length=5,identification=41568,offset=0,option=None,proto=6,src='10.0.0.2',tos=0,total_length=52,ttl=64,version=4)
------
_packet_in_handler: src_mac -> 00:00:00:00:00:01
_packet_in_handler: dst_mac -> 00:00:00:00:00:02
_packet_in_handler: ipv4(csum=9922,dst='10.0.0.2',flags=2,header_length=5,identification=0,offset=0,option=None,proto=6,src='10.0.0.1',tos=0,total_length=52,ttl=64,version=4)
------
mininet>
mininet>