P4-learning——send_to_cpu

send_to_cpu

编写p4语言时不用写匹配规则，可以由控制器编写规则

拓扑

{
  "program": "send_to_cpu.p4",
  "switch": "simple_switch",
  "compiler": "p4c",
  "options": "--target bmv2 --arch v1model --std p4-16",
  "switch_cli": "simple_switch_CLI",
  "cli": true,
  "pcap_dump": true,
  "enable_log": true,
  "cpu_port": true,
  "topo_module": {
    "file_path": "",
    "module_name": "p4utils.mininetlib.apptopo",
    "object_name": "AppTopo"
  },
  "controller_module": null,
  "topodb_module": {
    "file_path": "",
    "module_name": "p4utils.utils.topology",
    "object_name": "Topology"
  },
  "mininet_module": {
    "file_path": "",
    "module_name": "p4utils.mininetlib.p4net",
    "object_name": "P4Mininet"
  },
  "topology": {
    "links": [["h1","s1"], ["s3","h2"], ["s1","s2"], ["s2","s3"]],
    "hosts": {
      "h1": {
      },
      "h2": {
      }
    },
    "switches": {
      "s1": {
        "cli_input": "s1-commands.txt",
        "program": "send_to_cpu.p4",
        "cpu_port": true
      },
      "s2": {
        "cli_input": "s2-commands.txt",
        "program": "send_to_cpu.p4",
        "cpu_port": true
      },
      "s3": {
        "cli_input": "s3-commands.txt",
        "program": "send_to_cpu.p4",
        "cpu_port": true
      }		
    }
  }

}

p4文件

/* -*- P4_16 -*- */
#include <core.p4>
#include <v1model.p4>

const bit<16> TYPE_IPV4 = 0x800;

/*************************************************************************
*********************** H E A D E R S  ***********************************
*************************************************************************/

typedef bit<9>  egressSpec_t;
typedef bit<48> macAddr_t;
typedef bit<32> ip4Addr_t;

header ethernet_t {
    macAddr_t dstAddr;
    macAddr_t srcAddr;
    bit<16>   etherType;
}

header ipv4_t {
    bit<4>    version;
    bit<4>    ihl;
    bit<8>    tos;
    bit<16>   totalLen;
    bit<16>   identification;
    bit<3>    flags;
    bit<13>   fragOffset;
    bit<8>    ttl;
    bit<8>    protocol;
    bit<16>   hdrChecksum;
    ip4Addr_t srcAddr;
    ip4Addr_t dstAddr;
}

struct metadata {	
}

struct headers {
    ethernet_t   ethernet;
    ipv4_t       ipv4;
}

/*************************************************************************
*********************** P A R S E R  ***********************************
*************************************************************************/

parser MyParser(packet_in packet,
                out headers hdr,
                inout metadata meta,
                inout standard_metadata_t standard_metadata) {

    state start {

        packet.extract(hdr.ethernet);
        transition select(hdr.ethernet.etherType){

            TYPE_IPV4: ipv4;
            default: accept;
        }

    }

    state ipv4 {

        packet.extract(hdr.ipv4);
        transition accept;
    }

}


/*************************************************************************
************   C H E C K S U M    V E R I F I C A T I O N   *************
*************************************************************************/

control MyVerifyChecksum(inout headers hdr, inout metadata meta) {
    apply {  }
}


/*************************************************************************
**************  I N G R E S S   P R O C E S S I N G   *******************
*************************************************************************/

control MyIngress(inout headers hdr,
                  inout metadata meta,
                  inout standard_metadata_t standard_metadata) {

    action drop() {
        mark_to_drop(standard_metadata);
    }

    action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) {

        //set the src mac address as the previous dst, this is not correct right?
        hdr.ethernet.srcAddr = hdr.ethernet.dstAddr;

       //set the destination mac address that we got from the match in the table
        hdr.ethernet.dstAddr = dstAddr;

        //set the output port that we also get from the table
        standard_metadata.egress_spec = port;

        //decrease ttl by 1
        hdr.ipv4.ttl = hdr.ipv4.ttl -1;

    }

    action to_cpu(egressSpec_t port) {
        standard_metadata.egress_spec = port;
    }

    table ipv4_lpm {
        key = {
            hdr.ipv4.dstAddr: lpm;
        }
        actions = {
            ipv4_forward;
	    to_cpu;	
            drop;
        }
        size = 1024;
    }

    apply {

        //only if IPV4 the rule is applied. Therefore other packets will not be forwarded.
        if (hdr.ipv4.isValid()){
            ipv4_lpm.apply();

        }
    }
}

/*************************************************************************
****************  E G R E S S   P R O C E S S I N G   *******************
*************************************************************************/

control MyEgress(inout headers hdr,
                 inout metadata meta,
                 inout standard_metadata_t standard_metadata) {
    apply {
    }
}

/*************************************************************************
*************   C H E C K S U M    C O M P U T A T I O N   **************
*************************************************************************/

control MyComputeChecksum(inout headers hdr, inout metadata meta) {
     apply {
	update_checksum(
	    hdr.ipv4.isValid(),
            { hdr.ipv4.version,
	      hdr.ipv4.ihl,
              hdr.ipv4.tos,
              hdr.ipv4.totalLen,
              hdr.ipv4.identification,
              hdr.ipv4.flags,
              hdr.ipv4.fragOffset,
              hdr.ipv4.ttl,
              hdr.ipv4.protocol,
              hdr.ipv4.srcAddr,
              hdr.ipv4.dstAddr },
            hdr.ipv4.hdrChecksum,
            HashAlgorithm.csum16);
    }
}


/*************************************************************************
***********************  D E P A R S E R  *******************************
*************************************************************************/

control MyDeparser(packet_out packet, in headers hdr) {
    apply {

        //parsed headers have to be added again into the packet.
	packet.emit(hdr.ethernet);        
        packet.emit(hdr.ipv4);

    }
}

/*************************************************************************
***********************  S W I T C H  *******************************
*************************************************************************/

//switch architecture
V1Switch(
MyParser(),
MyVerifyChecksum(),
MyIngress(),
MyEgress(),
MyComputeChecksum(),
MyDeparser()
) main;

控制器

import nnpy
import struct
from p4utils.utils.topology import Topology
from p4utils.utils.sswitch_API import SimpleSwitchAPI
#from scapy.all import Ether, sniff, Packet, BitField
from scapy.all import *

rules=[]

class myController(object):

    def __init__(self):
        self.topo = Topology(db="topology.db")
	self.controllers = {}
	self.connect_to_switches()
        
    def connect_to_switches(self):
        for p4switch in self.topo.get_p4switches():
            thrift_port = self.topo.get_thrift_port(p4switch)
            #print "p4switch:", p4switch, "thrift_port:", thrift_port
            self.controllers[p4switch] = SimpleSwitchAPI(thrift_port) 	

    def recv_msg_cpu(self, pkt):
        print "-------------------------------------------------------------------"
	global rules
	print "interface:", pkt.sniffed_on
	print "summary:", pkt.summary()
        if IP in pkt:
          ip_src=pkt[IP].src
          ip_dst=pkt[IP].dst
          print "ip_src:", ip_src, " ip_dst:", ip_dst
	  if (ip_src, ip_dst) not in rules:
            rules.append((ip_src, ip_dst))
            print "rules:", rules
          else:
	    return 
       
        switches = {sw_name:{} for sw_name in self.topo.get_p4switches().keys()}
        #print "switches:", switches
        for sw_name, controller in self.controllers.items():
         for host in self.topo.get_hosts_connected_to(sw_name):
           host_ip_addr = self.topo.get_host_ip(host)
	   if ip_src == host_ip_addr:
             sw_src = sw_name
             
           if ip_dst == host_ip_addr:
	     sw_dst = sw_name  
             sw_port = self.topo.node_to_node_port_num(sw_name, host)
             host_ip = self.topo.get_host_ip(host) + "/32"
             host_mac = self.topo.get_host_mac(host)
             #print host, "(", host_ip, host_mac, ")", "-->", sw_name, "with port:", sw_port
 
             #add rule
             print "table_add at {}:".format(sw_name)
             self.controllers[sw_name].table_add("ipv4_lpm", "ipv4_forward", [str(host_ip)], [str(host_mac), str(sw_port)])

        print "sw_src:", sw_src, "sw_dst:", sw_dst   
        paths = self.topo.get_shortest_paths_between_nodes(sw_src, sw_dst)
        sw_1=sw_src
        for next_hop in paths[0][1:]:
         host_ip = ip_dst + "/32"
         sw_port = self.topo.node_to_node_port_num(sw_1, next_hop)
         dst_sw_mac = self.topo.node_to_node_mac(next_hop, sw_1)
         #add rule
         print "table_add at {}:".format(sw_1)
         self.controllers[sw_1].table_add("ipv4_lpm", "ipv4_forward", [str(host_ip)],
                                                    [str(dst_sw_mac), str(sw_port)])
         sw_1=next_hop

	print "send original packet back from ", pkt.sniffed_on
        sendp(pkt, iface=pkt.sniffed_on, verbose=False)
            

 
      
    def run_cpu_port_loop(self):
        cpu_interfaces = [str(self.topo.get_cpu_port_intf(sw_name).replace("eth0", "eth1")) for sw_name in self.controllers]
	sniff(iface=cpu_interfaces, prn=self.recv_msg_cpu)
        
if __name__ == "__main__":
    controller = myController()
    controller.run_cpu_port_loop()

告知交换机发送到cpu的端口

table_set_default ipv4_lpm to_cpu 3

测试

运行p4run后，python开启控制器