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dhcp.py
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dhcp.py
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# Copyright (C) 2013 Nippon Telegraph and Telephone Corporation.
# Copyright (C) 2013 YAMAMOTO Takashi <yamamoto at valinux co jp>
#
# 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.
# a simple ICMP Echo Responder
from ryu.base import app_manager
from ryu.lib import addrconv
from ryu.controller import ofp_event
from ryu.controller.handler import CONFIG_DISPATCHER, MAIN_DISPATCHER
from ryu.controller.handler import set_ev_cls
from ryu.ofproto import ofproto_v1_3
from ryu.lib.packet import packet
from ryu.lib.packet import ethernet
from ryu.lib.packet import ipv4
from ryu.lib.packet import udp
from ryu.lib.packet import dhcp
class DHCPResponder(app_manager.RyuApp):
OFP_VERSIONS = [ofproto_v1_3.OFP_VERSION]
def __init__(self, *args, **kwargs):
super(DHCPResponder, self).__init__(*args, **kwargs)
self.hw_addr = '0a:e4:1c:d1:3e:44'
self.dhcp_server = '192.168.1.1'
self.netmask = '255.255.255.0'
self.dns = '8.8.8.8'
self.bin_dns = addrconv.ipv4.text_to_bin(self.dns)
self.hostname = 'huehuehue'
self.bin_netmask = addrconv.ipv4.text_to_bin(self.netmask)
self.bin_server = addrconv.ipv4.text_to_bin(self.dhcp_server)
self.ip_addr = '192.0.2.9'
@set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
def _switch_features_handler(self, ev):
msg = ev.msg
datapath = msg.datapath
ofproto = datapath.ofproto
parser = datapath.ofproto_parser
actions = [parser.OFPActionOutput(port=ofproto.OFPP_CONTROLLER,
max_len=ofproto.OFPCML_NO_BUFFER)]
inst = [parser.OFPInstructionActions(type_=ofproto.OFPIT_APPLY_ACTIONS,
actions=actions)]
mod = parser.OFPFlowMod(datapath=datapath,
priority=0,
match=parser.OFPMatch(),
instructions=inst)
datapath.send_msg(mod)
@set_ev_cls(ofp_event.EventOFPPacketIn, MAIN_DISPATCHER)
def _packet_in_handler(self, ev):
msg = ev.msg
datapath = msg.datapath
port = msg.match['in_port']
pkt = packet.Packet(data=msg.data)
pkt_dhcp = dhcp.dhcp.parser(pkt[3])
if not pkt_dhcp:
return
else:
self._handle_dhcp(datapath, port, pkt)
return
def assemble_ack(self, pkt):
req_eth = pkt.get_protocol(ethernet.ethernet)
req_ipv4 = pkt.get_protocol(ipv4.ipv4)
req_udp = pkt.get_protocol(udp.udp)
req = dhcp.dhcp.parser(pkt[3])
req[0].options.option_list.remove(next(opt for opt in req[0].options.option_list if opt.tag == 53))
req[0].options.option_list.insert(0, dhcp.option(tag=51, value='8640'))
req[0].options.option_list.insert(0, dhcp.option(tag=53, value='05'.decode('hex')))
ack_pkt = packet.Packet()
ack_pkt.add_protocol(ethernet.ethernet(ethertype=req_eth.ethertype, dst=req_eth.src, src=self.hw_addr))
ack_pkt.add_protocol(ipv4.ipv4(dst=req_ipv4.dst, src=self.dhcp_server, proto=req_ipv4.proto))
ack_pkt.add_protocol(udp.udp(src_port=67,dst_port=68))
ack_pkt.add_protocol(dhcp.dhcp(op=2, chaddr=req_eth.src,
siaddr=self.dhcp_server,
boot_file=req[0].boot_file,
yiaddr=self.ip_addr,
xid=req[0].xid,
options=req[0].options))
self.logger.info("ASSEMBLED ACK: %s" % ack_pkt)
return ack_pkt
def assemble_offer(self, pkt):
disc_eth = pkt.get_protocol(ethernet.ethernet)
disc_ipv4 = pkt.get_protocol(ipv4.ipv4)
disc_udp = pkt.get_protocol(udp.udp)
disc = dhcp.dhcp.parser(pkt[3])
disc[0].options.option_list.remove(next(opt for opt in disc[0].options.option_list if opt.tag == 55))
disc[0].options.option_list.remove(next(opt for opt in disc[0].options.option_list if opt.tag == 53))
disc[0].options.option_list.remove(next(opt for opt in disc[0].options.option_list if opt.tag == 12))
disc[0].options.option_list.insert(0, dhcp.option(tag=1, value=self.bin_netmask))
disc[0].options.option_list.insert(0, dhcp.option(tag=3, value=self.bin_server))
disc[0].options.option_list.insert(0, dhcp.option(tag=6, value=self.bin_dns))
disc[0].options.option_list.insert(0, dhcp.option(tag=12, value=self.hostname))
disc[0].options.option_list.insert(0, dhcp.option(tag=53, value='02'.decode('hex')))
disc[0].options.option_list.insert(0, dhcp.option(tag=54, value=self.bin_server))
offer_pkt = packet.Packet()
offer_pkt.add_protocol(ethernet.ethernet(ethertype=disc_eth.ethertype, dst=disc_eth.src, src=self.hw_addr))
offer_pkt.add_protocol(ipv4.ipv4(dst=disc_ipv4.dst, src=self.dhcp_server, proto=disc_ipv4.proto))
offer_pkt.add_protocol(udp.udp(src_port=67,dst_port=68))
offer_pkt.add_protocol(dhcp.dhcp(op=2, chaddr=disc_eth.src,
siaddr=self.dhcp_server,
boot_file=disc[0].boot_file,
yiaddr=self.ip_addr,
xid=disc[0].xid,
options=disc[0].options))
self.logger.info("ASSEMBLED OFFER: %s" % offer_pkt)
return offer_pkt
def get_state(self, pkt_dhcp):
dhcp_state = ord([opt for opt in pkt_dhcp[0].options.option_list if opt.tag == 53][0].value)
if dhcp_state == 1:
state = 'DHCPDISCOVER'
elif dhcp_state == 2:
state = 'DHCPOFFER'
elif dhcp_state == 3:
state = 'DHCPREQUEST'
elif dhcp_state == 5:
state = 'DHCPACK'
return state
def _handle_dhcp(self, datapath, port, pkt):
pkt_dhcp = dhcp.dhcp.parser(pkt[3])
dhcp_state = self.get_state(pkt_dhcp)
self.logger.info("NEW DHCP %s PACKET RECEIVED: %s" % (dhcp_state, pkt_dhcp))
if dhcp_state == 'DHCPDISCOVER':
self._send_packet(datapath, port, self.assemble_offer(pkt))
elif dhcp_state == 'DHCPREQUEST':
self._send_packet(datapath, port, self.assemble_ack(pkt))
else:
return
def _send_packet(self, datapath, port, pkt):
ofproto = datapath.ofproto
parser = datapath.ofproto_parser
pkt.serialize()
self.logger.info("packet-out %s" % (pkt,))
data = pkt.data
actions = [parser.OFPActionOutput(port=port)]
out = parser.OFPPacketOut(datapath=datapath,
buffer_id=ofproto.OFP_NO_BUFFER,
in_port=ofproto.OFPP_CONTROLLER,
actions=actions,
data=data)
datapath.send_msg(out)