github nsg-ethz/p4-learning
examples
simple switch examples
基本示例
数据包反射
交换机将所有接收的数据包发回给发送者
network.py
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"""
+----+ +----+
| h1 +-------+ s1 +
+----+ +----+
"""
from p4utils.mininetlib.network_API import NetworkAPI
net = NetworkAPI()
# 网络配置选项
net.setLogLevel('info') # 设置日志等级
net.enableCli() # 启动mininet CLI
# 添加网络节点和链路
net.addP4Switch('s1') # 添加s1 p4交换机
net.setP4Source('s1','reflector.p4') # 给s1 添加p4文件
net.addHost('h1') # 添加主机h1
net.addLink('s1', 'h1') # 添加s1到h1的链路
# 设置分配策略
net.l2() # 2层分配策略
# 网络节点配置选项
net.enablePcapDumpAll() # 允许所有节点记录PcapDump
net.enableLogAll() # 允许所有节点记录日志
# 启动网络
net.startNetwork()
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reflector.p4
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/* -*- P4_16 -*- */
#include <core.p4>
#include <v1model.p4>
/*************************************************************************
*********************** H E A D E R S ***********************************
*************************************************************************/
//mac地址类型
typedef bit<48> macAddr_t;
//以太头
header ethernet_t {
macAddr_t dstAddr;
macAddr_t srcAddr;
bit<16> etherType;
}
//元数据
struct metadata {
/* empty */
}
//数据包头
struct headers {
ethernet_t ethernet;
}
/*************************************************************************
*********************** P A R S E R ***********************************
*************************************************************************/
//状态机
parser MyParser(packet_in packet,
out headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
//起始状态
state start{
//读取以太头
packet.extract(hdr.ethernet);
//转换状态为接受
transition accept;
}
}
/*************************************************************************
************ C H E C K S U M V E R I F I C A T I O N *************
*************************************************************************/
//校验和控制管道，这里管道流程为空，因为交换机仅作为反射器，不需要校验和
control MyVerifyChecksum(inout headers hdr, inout metadata meta) {
//管道流程
apply { }
}
/*************************************************************************
************** I N G R E S S P R O C E S S I N G *******************
*************************************************************************/
//入口管道
control MyIngress(inout headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
//定义swap_mac动作，用于交换以太头的源mac和目的mac
action swap_mac(){
macAddr_t tmp;
tmp = hdr.ethernet.srcAddr;
hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;
hdr.ethernet.dstAddr = tmp;
}
//管道流程
apply {
//交换源mac和目的mac
swap_mac();
//将出口设置为和入口所在端口
standard_metadata.egress_spec = standard_metadata.ingress_port;
}
}
/*************************************************************************
**************** E G R E S S P R O C E S S I N G *******************
*************************************************************************/
//出口管道
control MyEgress(inout headers hdr,
inout metadata meta,
inout standard_metadata_t standard_metadata) {
//管道流程为空
apply { }
}
/*************************************************************************
************* C H E C K S U M C O M P U T A T I O N **************
*************************************************************************/
//计算校验和
control MyComputeChecksum(inout headers hdr, inout metadata meta) {
apply { }
}
/*************************************************************************
*********************** D E P A R S E R *******************************
*************************************************************************/
//出口解析器
control MyDeparser(packet_out packet, in headers hdr) {
apply {
// 将修改后的以太头添加给数据包载荷
packet.emit(hdr.ethernet);
}
}
/*************************************************************************
*********************** S W I T C H *******************************
*************************************************************************/
//交换机流程
V1Switch(
MyParser(),
MyVerifyChecksum(),
MyIngress(),
MyEgress(),
MyComputeChecksum(),
MyDeparser()
) main;
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send_receive.py
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#!/usr/bin/env python3
import sys
import socket
import random
import time
from threading import Thread, Event
from scapy.all import *
# 嗅探类，继承线程
class Sniffer(Thread):
def __init__(self, interface="eth0"):
super(Sniffer, self).__init__()
self.interface = interface
self.my_mac = get_if_hwaddr(interface)
self.daemon = True
self.socket = None
self.stop_sniffer = Event()
def isNotOutgoing(self, pkt):
return pkt[Ether].src != self.my_mac
def run(self):
self.socket = conf.L2listen(
type=ETH_P_ALL,
iface=self.interface,
filter="ip"
)
sniff(opened_socket=self.socket, prn=self.print_packet, lfilter=self.isNotOutgoing,
stop_filter=self.should_stop_sniffer)
def join(self, timeout=None):
self.stop_sniffer.set()
super(Sniffer, self).join(timeout)
def should_stop_sniffer(self, packet):
return self.stop_sniffer.isSet()
def print_packet(self, packet):
print("[!] A packet was reflected from the switch: ")
# packet.show()
ether_layer = packet.getlayer(Ether)
print(("[!] Info: {src} -> {dst}\n".format(src=ether_layer.src, dst=ether_layer.dst)))
def get_if():
ifs = get_if_list()
iface = None # "h1-eth0"
for i in get_if_list():
if "eth0" in i:
iface = i
break
if not iface:
print("Cannot find eth0 interface")
exit(1)
return iface
def send_packet(iface, addr):
input("Press the return key to send a packet:")
print("Sending on interface %s to %s\n" % (iface, str(addr)))
pkt = Ether(src=get_if_hwaddr(iface), dst='00:01:02:03:04:05')
pkt = pkt / IP(dst=addr)
sendp(pkt, iface=iface, verbose=False)
def main():
addr = "10.0.0.2"
addr = socket.gethostbyname(addr)
iface = get_if()
listener = Sniffer(iface)
listener.start()
time.sleep(0.1)
try:
while True:
send_packet(iface, addr)
time.sleep(0.5)
except KeyboardInterrupt:
print("[*] Stop sniffing")
listener.join(2.0)
if listener.isAlive():
listener.socket.close()
if __name__ == '__main__':
main()
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