P4-DNS

[Topology]

Normally, H1 will use DNS packet to obtain the ip address for www.a.com from H3 (dns-server). This will take some time due to the long distance from H1 to H3. If we can direct the DNS query packet to H2 first. H2 is a dns forwarder. If there is no hit in the cache, H2 will forward the DNS query to H3. When the DNS response packet is back to H2. H2 will keep a copy in its cache. Then H2 sends the response to H1. If H1 or other local hosts will query the IP address for www.a.com again, H2 will respond quickly due to the ip address for www.a.com has already in its cache.

 

Note. If you want to run the example, you have to refer to http://csie.nqu.edu.tw/smallko/sdn/p4-dockernet.htm first. Because H2 and H3 is a docker node.

 

[basic16.p4]

#include <core.p4>

#include <v1model.p4>

 

header ethernet_t {

    bit<48> dstAddr;

    bit<48> srcAddr;

    bit<16> etherType;

}

 

header ipv4_t {

    bit<4>  version;

    bit<4>  ihl;

    bit<8>  diffserv;

    bit<16> totalLen;

    bit<16> identification;

    bit<3>  flags;

    bit<13> fragOffset;

    bit<8>  ttl;

    bit<8>  protocol;

    bit<16> hdrChecksum;

    bit<32> srcAddr;

    bit<32> dstAddr;

}

 

header udp_t {

    bit<16> srcPort;

    bit<16> dstPort;

    bit<16> length_;

    bit<16> checksum;

}

 

struct metadata {

}

 

struct headers {

    ethernet_t ethernet;

    ipv4_t     ipv4;

    udp_t      udp;

}

 

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

 

    @name(".parse_ethernet") state parse_ethernet {

        packet.extract(hdr.ethernet);

        transition select(hdr.ethernet.etherType) {

            16w0x800: parse_ipv4;

            default: accept;

        }

    }

    @name(".parse_ipv4") state parse_ipv4 {

        packet.extract(hdr.ipv4);

        transition select(hdr.ipv4.protocol) {

            8w0x11: parse_udp;

            default: accept;

        }

    }

    @name(".parse_udp") state parse_udp {

        packet.extract<udp_t>(hdr.udp);

        transition accept;

    }

    @name(".start") state start {

        transition parse_ethernet;

    }

}

 

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

    action forward(bit<32> src_ip, bit<48> dmac, bit<9> port) {

        standard_metadata.egress_spec = port;

        hdr.ethernet.dstAddr = dmac;

        hdr.ipv4.srcAddr = src_ip;

        hdr.ipv4.ttl = hdr.ipv4.ttl + 8w255;

    }

    apply {

      if(hdr.udp.srcPort==53 && hdr.ipv4.dstAddr==0x0a000101 && standard_metadata.ingress_port==2) {

         forward(0x0a000303, 0x000000000101, 2);

       }

    }

}

 

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

    action nop() {

    }

 

    action forward(bit<32> dst_ip, bit<48> dmac, bit<9> port) {

        standard_metadata.egress_spec = port;

        hdr.ethernet.dstAddr = dmac;

        hdr.ipv4.dstAddr = dst_ip;

        hdr.ipv4.ttl = hdr.ipv4.ttl + 8w255;

    }

 

    action myforward(bit<48> dmac, bit<9> port) {

        standard_metadata.egress_spec = port;

        hdr.ethernet.dstAddr = dmac;

        hdr.ipv4.ttl = hdr.ipv4.ttl + 8w255;

    }

  

    table ipforward {

        actions = {

           myforward;

           nop;

        }

        key = {

            hdr.ipv4.dstAddr: exact;

        }

        size = 1024;

        default_action = nop();

    }

    apply {

       if(hdr.udp.dstPort==53 && hdr.ipv4.srcAddr==0x0a000101 && standard_metadata.ingress_port==1) {

         forward(0x0a000202, 0x000000000202, 2);

       }

       ipforward.apply();

    }

}

 

control DeparserImpl(packet_out packet, in headers hdr) {

    apply {

        packet.emit(hdr.ethernet);

        packet.emit(hdr.ipv4);

        packet.emit(hdr.udp);

    }

}

 

control verifyChecksum(inout headers hdr, inout metadata meta) {

    apply {

    }

}

 

control computeChecksum(inout headers hdr, inout metadata meta) {

    apply {

        update_checksum(true, { hdr.ipv4.version, hdr.ipv4.ihl, hdr.ipv4.diffserv, 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);

         update_checksum_with_payload(true, { hdr.ipv4.srcAddr, hdr.ipv4.dstAddr, 8w0, hdr.ipv4.protocol, hdr.udp.length_, hdr.udp.srcPort, hdr.udp.dstPort,  hdr.udp.length_}, hdr.udp.checksum, HashAlgorithm.csum16);

    }      

}

 

V1Switch(ParserImpl(), verifyChecksum(), ingress(), egress(), computeChecksum(), DeparserImpl()

)main;

 

 

[cmd.txt]

table_add ipforward myforward 10.0.1.1 => 00:00:00:00:01:01 1

table_add ipforward myforward 10.0.2.2 => 00:00:00:00:02:02 2

table_add ipforward myforward 10.0.3.3 => 00:00:00:00:03:03 3

                                                                                                                                            

[cmd_add.py]

import os

os.system('sudo /home/vagrant/behavioral-model/targets/simple_switch/simple_switch_CLI --thrift-port=9090 < cmd.txt')

 

[test_topo.py]

import os

from mininet.net import  Containernet

from mininet.topo import Topo

from mininet.log import setLogLevel, info

from mininet.cli import CLI

from mininet.node import RemoteController

from mininet.node import Docker

from p4_mininet import P4Switch, P4Host

from mininet.link import TCLink

 

import argparse

from time import sleep

 

parser = argparse.ArgumentParser(description='Mininet demo')

parser.add_argument('--behavioral-exe', help='Path to behavioral executable',

                    type=str, action="store", required=False, default='simple_switch' )

parser.add_argument('--thrift-port', help='Thrift server port for table updates',

                    type=int, action="store", default=9090)

parser.add_argument('--num-hosts', help='Number of hosts to connect to switch',

                    type=int, action="store", default=2)

parser.add_argument('--mode', choices=['l2', 'l3'], type=str, default='l3')

parser.add_argument('--json', help='Path to JSON config file',

                    type=str, action="store", required=True)

parser.add_argument('--pcap-dump', help='Dump packets on interfaces to pcap files',

                    type=str, action="store", required=False, default=False)

 

 

args = parser.parse_args()

       

def main():

    net = Containernet(host = P4Host, controller = None, link=TCLink)

    switch1 = net.addSwitch('s1', sw_path = args.behavioral_exe, json_path = args.json, thrift_port = args.thrift_port, cls = P4Switch, pcap_dump = args.pcap_dump)

    host1 = net.addHost('h1', mac = '00:00:00:00:01:01', ip="10.0.1.1/24")

    host2 = net.addDocker('h2', mac = '00:00:00:00:02:02',  ip= '10.0.2.2/24', dimage="smallko/php-apache-dev:dns-cache")

    host3 = net.addDocker('h3', mac = '00:00:00:00:03:03',  ip= '10.0.3.3/24', dimage="smallko/php-apache-dev:dns-server")

    #r1 = net.addHost('r1', mac = '00:00:00:01:01:01', ip="10.0.1.254/24")

 

    net.addLink(host1, switch1, port1 = 0, port2 = 1, bw=100, delay='1ms')

    net.addLink(host2, switch1, port1 = 0, port2 = 2, bw=100, delay='1ms')

    net.addLink(host3, switch1, port1 = 0, port2 = 3, bw=100, delay='100ms')

    #net.addLink(host1, r1, port1 = 0, port2 = 0, bw=100, delay='1ms')

    #net.addLink(host2, r1, port1 = 0, port2 = 1, bw=100, delay='1ms')

    #net.addLink(host3, r1, port1 = 0, port2 = 2, bw=100, delay='100ms')

                                                                                                                                            

    net.start()

    #h1,h2,h3,r1=net.get('h1','h2','h3','r1')

    h1,h2,h3=net.get('h1','h2','h3')

    #r1.cmd("echo 1 > /proc/sys/net/ipv4/ip_forward")

    #r1.cmd("ifconfig eth0 down")

    #r1.cmd("ifconfig r1-eth1 down")

    #r1.cmd("ifconfig r1-eth2 down")

    #r1.cmd("ip addr add 10.0.1.254/24 brd + dev eth0")

    #r1.cmd("ip addr add 10.0.2.254/24 brd + dev r1-eth1")

    #r1.cmd("ip addr add 10.0.3.254/24 brd + dev r1-eth2")

    #r1.cmd("ifconfig eth0 hw ether 00:00:00:01:01:01")

    #r1.cmd("ifconfig r1-eth1 hw ether 00:00:00:02:02:02")

    #r1.cmd("ifconfig r1-eth2 hw ether 00:00:00:03:03:03")

    #r1.cmd("ifconfig eth0 up")

    #r1.cmd("ifconfig r1-eth1 up")

    #r1.cmd("ifconfig r1-eth2 up")                                                                                   

    h1.cmd("arp -s 10.0.1.254 00:00:00:01:01:01")

    h1.cmd("ip route add default via 10.0.1.254")

    h2.cmd("arp -s 10.0.2.254 00:00:00:02:02:02")

    h2.cmd("ip route del default")

    h2.cmd("ip route add default via 10.0.2.254")

   h2.cmd("/etc/init.d/bind9 start")

    h3.cmd("arp -s 10.0.3.254 00:00:00:03:03:03")

    h3.cmd("ip route del default")

    h3.cmd("ip route add default via 10.0.3.254")

    h3.cmd("/etc/init.d/bind9 start")

 

    sleep(1)

 

    print('\033[0;32m'),

    print "Gotcha!"

    print('\033[0m')

 

    CLI(net)

    try:

        net.stop()

    except:

        print('\033[0;31m'),

        print('Stop error! Trying sudo mn -c')

        print('\033[0m')

        os.system('sudo mn -c')

        print('\033[0;32m'),

        print ('Stop successfully!')

        print('\033[0m')

 

if __name__ == '__main__':

    setLogLevel('info')

    main()

 

[start_test_topo.py]

import os

 

os.system("sudo python test_topo.py --behavioral-exe /home/vagrant/behavioral-model/targets/simple_switch/simple_switch --json basic.json")

 

[p4_mininet.py]

# Copyright 2013-present Barefoot Networks, Inc.

#

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

#

#   http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

#

 

from mininet.net import Mininet

from mininet.node import Switch, Host

from mininet.log import setLogLevel, info, error, debug

from mininet.moduledeps import pathCheck

from sys import exit

import os

import tempfile

import socket

 

class P4Host(Host):

    def config(self, **params):

        r = super(Host, self).config(**params)

 

        self.defaultIntf().rename("eth0")

 

        for off in ["rx", "tx", "sg"]:

            cmd = "/sbin/ethtool --offload eth0 %s off" % off

            self.cmd(cmd)

 

        # disable IPv6

        self.cmd("sysctl -w net.ipv6.conf.all.disable_ipv6=1")

        self.cmd("sysctl -w net.ipv6.conf.default.disable_ipv6=1")

        self.cmd("sysctl -w net.ipv6.conf.lo.disable_ipv6=1")

 

        return r

 

    def describe(self):

        print "**********"

        print self.name

        print "default interface: %s\t%s\t%s" %(

            self.defaultIntf().name,

            self.defaultIntf().IP(),

            self.defaultIntf().MAC()

        )

        print "**********"

 

class P4Switch(Switch):

    """P4 virtual switch"""

    device_id = 0

 

    def __init__(self, name, sw_path = None, json_path = None,

                 thrift_port = None,

                 pcap_dump = False,

                 log_console = True,

                 verbose = False,

                 device_id = None,

                 enable_debugger = False,

                 **kwargs):

        Switch.__init__(self, name, **kwargs)

        assert(sw_path)

        assert(json_path)

        # make sure that the provided sw_path is valid

        pathCheck(sw_path)

        # make sure that the provided JSON file exists

        if not os.path.isfile(json_path):

            error("Invalid JSON file.\n")

            exit(1)

        self.sw_path = sw_path

        self.json_path = json_path

        self.verbose = verbose

        logfile = "/tmp/p4s.{}.log".format(self.name)

        self.output = open(logfile, 'w')

        self.thrift_port = thrift_port

        self.pcap_dump = pcap_dump

        self.enable_debugger = enable_debugger

        self.log_console = log_console

        if device_id is not None:

            self.device_id = device_id

            P4Switch.device_id = max(P4Switch.device_id, device_id)

        else:

            self.device_id = P4Switch.device_id

            P4Switch.device_id += 1

        self.nanomsg = "ipc:///tmp/bm-{}-log.ipc".format(self.device_id)

 

    @classmethod

    def setup(cls):

        pass

 

    def check_switch_started(self, pid):

        """While the process is running (pid exists), we check if the Thrift

        server has been started. If the Thrift server is ready, we assume that

        the switch was started successfully. This is only reliable if the Thrift

        server is started at the end of the init process"""

        while True:

            if not os.path.exists(os.path.join("/proc", str(pid))):

                return False

            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

            sock.settimeout(0.5)

            result = sock.connect_ex(("localhost", self.thrift_port))

            if result == 0:

                return  True

 

    def start(self, controllers):

        "Start up a new P4 switch"

        info("Starting P4 switch {}.\n".format(self.name))

        args = [self.sw_path]

        for port, intf in self.intfs.items():

            if not intf.IP():

                args.extend(['-i', str(port) + "@" + intf.name])

 

        #wuwzhs edit in 2017/11/10

        #args.extend(['-i 3@veth1'])

 

        if self.pcap_dump:

            args.append("--pcap")

            # args.append("--useFiles")

        if self.thrift_port:

            args.extend(['--thrift-port', str(self.thrift_port)])

        if self.nanomsg:

            args.extend(['--nanolog', self.nanomsg])

        args.extend(['--device-id', str(self.device_id)])

        P4Switch.device_id += 1

        args.append(self.json_path)

        if self.enable_debugger:

            args.append("--debugger")

        if self.log_console:

            args.append("--log-console")

        logfile = "/tmp/p4s.{}.log".format(self.name)

        info(' '.join(args) + "\n")

 

        pid = None

        with tempfile.NamedTemporaryFile() as f:

            # self.cmd(' '.join(args) + ' > /dev/null 2>&1 &')

            self.cmd(' '.join(args) + ' >' + logfile + ' 2>&1 & echo $! >> ' + f.name)

            pid = int(f.read())

        debug("P4 switch {} PID is {}.\n".format(self.name, pid))

        if not self.check_switch_started(pid):

            error("P4 switch {} did not start correctly.\n".format(self.name))

            exit(1)

        info("P4 switch {} has been started.\n".format(self.name))

 

    def stop(self):

        "Terminate P4 switch."

        self.output.flush()

        self.cmd('kill %' + self.sw_path)

        self.cmd('wait')

        self.deleteIntfs()

 

    def attach(self, intf):

        "Connect a data port"

        assert(0)

 

    def detach(self, intf):

        "Disconnect a data port"

        assert(0)

 

[Execution]

Download the docker image

 

Start simulation and add rules.

 

First time, h1 will need 226msec to obtain the IP address (10.0.3.4) for www.a.com

 

Next, it will take only 9 msec to obtain the IP address.

 

Reference

https://www.digitalocean.com/community/tutorials/how-to-configure-bind-as-a-caching-or-forwarding-dns-server-on-ubuntu-14-04

 

 

Dr. Chih-Heng Ke (smallko@gmail.com)

Department of Computer Science and Information Engineering,

National Quemoy University, Kinmen, Taiwan.