Synnefo » snf-nfdhcpd

#!/usr/bin/env python

#

# nfdcpd: A promiscuous, NFQUEUE-based DHCP server for virtual machine hosting

# Copyright (c) 2010 GRNET SA

#

#    This program is free software; you can redistribute it and/or modify

#    it under the terms of the GNU General Public License as published by

#    the Free Software Foundation; either version 2 of the License, or

#    (at your option) any later version.

#

#    This program is distributed in the hope that it will be useful,

#    but WITHOUT ANY WARRANTY; without even the implied warranty of

#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

#    GNU General Public License for more details.

#

#    You should have received a copy of the GNU General Public License along

#    with this program; if not, write to the Free Software Foundation, Inc.,

#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

#

import os

import signal

import errno

import re

import sys

import glob

import time

import logging

import logging.handlers

import threading

import traceback

import daemon

import daemon.runner

import daemon.pidlockfile

import nfqueue

import pyinotify

import setproctitle

from lockfile import LockTimeout

import IPy

import socket

import select

from socket import AF_INET, AF_INET6

from scapy.data import ETH_P_ALL

from scapy.packet import BasePacket

from scapy.layers.l2 import Ether

from scapy.layers.inet import IP, UDP

from scapy.layers.inet6 import IPv6, ICMPv6ND_RA, ICMPv6ND_NA, \

                               ICMPv6NDOptDstLLAddr, \

                               ICMPv6NDOptPrefixInfo, \

                               ICMPv6NDOptRDNSS

from scapy.layers.dhcp import BOOTP, DHCP

from scapy.layers.dhcp6 import DHCP6_Reply, DHCP6OptDNSServers, \

                               DHCP6OptServerId, DHCP6OptClientId, \

                               DUID_LLT, DHCP6_InfoRequest, DHCP6OptDNSDomains

DEFAULT_CONFIG = "/etc/nfdhcpd/nfdhcpd.conf"

DEFAULT_PATH = "/var/run/ganeti-dhcpd"

DEFAULT_USER = "nobody"

DEFAULT_LEASE_LIFETIME = 604800 # 1 week

DEFAULT_LEASE_RENEWAL = 600  # 10 min

DEFAULT_RA_PERIOD = 300 # seconds

DHCP_DUMMY_SERVER_IP = "1.2.3.4"

LOG_FILENAME = "nfdhcpd.log"

SYSFS_NET = "/sys/class/net"

LOG_FORMAT = "%(asctime)-15s %(levelname)-8s %(message)s"

# Configuration file specification (see configobj documentation)

CONFIG_SPEC = """

[general]

pidfile = string()

datapath = string()

logdir = string()

user = string()

[dhcp]

enable_dhcp = boolean(default=True)

lease_lifetime = integer(min=0, max=4294967295)

lease_renewal = integer(min=0, max=4294967295)

server_ip = ip_addr()

dhcp_queue = integer(min=0, max=65535)

nameservers = ip_addr_list(family=4)

domain = string(default=None)

[ipv6]

enable_ipv6 = boolean(default=True)

ra_period = integer(min=1, max=4294967295)

rs_queue = integer(min=0, max=65535)

ns_queue = integer(min=0, max=65535)

dhcp_queue = integer(min=0, max=65535)

nameservers = ip_addr_list(family=6)

domains = force_list(default=None)

"""

DHCPDISCOVER = 1

DHCPOFFER = 2

DHCPREQUEST = 3

DHCPDECLINE = 4

DHCPACK = 5

DHCPNAK = 6

DHCPRELEASE = 7

DHCPINFORM = 8

DHCP_TYPES = {

    DHCPDISCOVER: "DHCPDISCOVER",

    DHCPOFFER: "DHCPOFFER",

    DHCPREQUEST: "DHCPREQUEST",

    DHCPDECLINE: "DHCPDECLINE",

    DHCPACK: "DHCPACK",

    DHCPNAK: "DHCPNAK",

    DHCPRELEASE: "DHCPRELEASE",

    DHCPINFORM: "DHCPINFORM",

}

DHCP_REQRESP = {

    DHCPDISCOVER: DHCPOFFER,

    DHCPREQUEST: DHCPACK,

    DHCPINFORM: DHCPACK,

    }

def get_indev(payload):

    try:

        indev_ifindex = payload.get_physindev()

        if indev_ifindex:

            logging.debug(" - Incoming packet from bridge with ifindex %s",

                          indev_ifindex)

            return indev_ifindex

    except AttributeError:

        #TODO: return error value

        logging.debug("No get_physindev() supported")

        return 0

    indev_ifindex = payload.get_indev()

    logging.debug(" - Incoming packet from tap with ifindex %s", indev_ifindex)

    return indev_ifindex

def parse_binding_file(path):

    """ Read a client configuration from a tap file

    """

    logging.info("Parsing binding file %s", path)

    try:

        iffile = open(path, 'r')

    except EnvironmentError, e:

        logging.warn(" - Unable to open binding file %s: %s", path, str(e))

        return None

    tap = os.path.basename(path)

    indev = None

    mac = None

    ip = None

    hostname = None

    subnet = None

    gateway = None

    subnet6 = None

    gateway6 = None

    eui64 = None

    def get_value(line):

        v = line.strip().split('=')[1]

        if v == '':

            return None

        return v

    for line in iffile:

        if line.startswith("IP="):

            ip = get_value(line)

        elif line.startswith("MAC="):

            mac = get_value(line)

        elif line.startswith("HOSTNAME="):

            hostname = get_value(line)

        elif line.startswith("INDEV="):

            indev = get_value(line)

        elif line.startswith("SUBNET="):

            subnet = get_value(line)

        elif line.startswith("GATEWAY="):

            gateway = get_value(line)

        elif line.startswith("SUBNET6="):

            subnet6 = get_value(line)

        elif line.startswith("GATEWAY6="):

            gateway6 = get_value(line)

        elif line.startswith("EUI64="):

            eui64 = get_value(line)

    try:

        return Client(tap=tap, mac=mac, ip=ip, hostname=hostname,

                      indev=indev, subnet=subnet, gateway=gateway,

                      subnet6=subnet6, gateway6=gateway6, eui64=eui64 )

    except ValueError:

        logging.warning(" - Cannot add client for host %s and IP %s on tap %s",

                        hostname, ip, tap)

        return None

class ClientFileHandler(pyinotify.ProcessEvent):

    def __init__(self, server):

        pyinotify.ProcessEvent.__init__(self)

        self.server = server

    def process_IN_DELETE(self, event):  # pylint: disable=C0103

        """ Delete file handler

        Currently this removes an interface from the watch list

        """

        self.server.remove_tap(event.name)

    def process_IN_CLOSE_WRITE(self, event):  # pylint: disable=C0103

        """ Add file handler

        Currently this adds an interface to the watch list

        """

        self.server.add_tap(os.path.join(event.path, event.name))

class Client(object):

    def __init__(self, tap=None, indev=None,

                 mac=None, ip=None, hostname=None,

                 subnet=None, gateway=None,

                 subnet6=None, gateway6=None, eui64=None):

        self.mac = mac

        self.ip = ip

        self.hostname = hostname

        self.indev = indev

        self.tap = tap

        self.subnet = subnet

        self.gateway = gateway

        self.net = Subnet(net=subnet, gw=gateway, dev=tap)

        self.subnet6 = subnet6

        self.gateway6 = gateway6

        self.net6 = Subnet(net=subnet6, gw=gateway6, dev=tap)

        self.eui64 = eui64

        self.open_socket()

    def is_valid(self):

        return self.mac is not None and self.hostname is not None

    def open_socket(self):

        logging.info(" - Opening L2 socket and binding to %s", self.tap)

        try:

            s = socket.socket(socket.AF_PACKET, socket.SOCK_RAW, ETH_P_ALL)

            s.setsockopt(socket.SOL_SOCKET, socket.SO_RCVBUF, 0)

            s.bind((self.tap, ETH_P_ALL))

            self.socket = s

        except socket.error, e:

            logging.warning(" - Cannot open socket %s", e)

    def sendp(self, data):

        if isinstance(data, BasePacket):

            data = str(data)

        logging.debug(" - Sending raw packet %r", data)

        try:

            count = self.socket.send(data, socket.MSG_DONTWAIT)

        except socket.error, e:

            logging.warn(" - Send with MSG_DONTWAIT failed: %s", str(e))

            self.socket.close()

            self.open_socket()

            raise e

        ldata = len(data)

        logging.debug(" - Sent %d bytes on %s", count, self.tap)

        if count != ldata:

            logging.warn(" - Truncated msg: %d/%d bytes sent",

                         count, ldata)

class Subnet(object):

    def __init__(self, net=None, gw=None, dev=None):

        if isinstance(net, str):

            try:

                self.net = IPy.IP(net)

            except ValueError, e:

                logging.warning(" - IPy error: %s", e)

                raise e

        else:

            self.net = net

        self.gw = gw

        self.dev = dev

    @property

    def netmask(self):

        """ Return the netmask in textual representation

        """

        return str(self.net.netmask())

    @property

    def broadcast(self):

        """ Return the broadcast address in textual representation

        """

        return str(self.net.broadcast())

    @property

    def prefix(self):

        """ Return the network as an IPy.IP

        """

        return self.net.net()

    @property

    def prefixlen(self):

        """ Return the prefix length as an integer

        """

        return self.net.prefixlen()

    @staticmethod

    def _make_eui64(net, mac):

        """ Compute an EUI-64 address from an EUI-48 (MAC) address

        """

        if mac is None:

            return None

        comp = mac.split(":")

        prefix = IPy.IP(net).net().strFullsize().split(":")[:4]

        eui64 = comp[:3] + ["ff", "fe"] + comp[3:]

        eui64[0] = "%02x" % (int(eui64[0], 16) ^ 0x02)

        for l in range(0, len(eui64), 2):

            prefix += ["".join(eui64[l:l+2])]

        return IPy.IP(":".join(prefix))

    def make_eui64(self, mac):

        """ Compute an EUI-64 address from an EUI-48 (MAC) address in this

        subnet.

        """

        return self._make_eui64(self.net, mac)

    def make_ll64(self, mac):

        """ Compute an IPv6 Link-local address from an EUI-48 (MAC) address

        """

        return self._make_eui64("fe80::", mac)

class VMNetProxy(object):  # pylint: disable=R0902

    def __init__(self, data_path, dhcp_queue_num=None,  # pylint: disable=R0913

                 rs_queue_num=None, ns_queue_num=None, dhcpv6_queue_num=None,

                 dhcp_lease_lifetime=DEFAULT_LEASE_LIFETIME,

                 dhcp_lease_renewal=DEFAULT_LEASE_RENEWAL,

                 dhcp_domain=None,

                 dhcp_server_ip=DHCP_DUMMY_SERVER_IP, dhcp_nameservers=None,

                 ra_period=DEFAULT_RA_PERIOD, ipv6_nameservers=None,

                 dhcpv6_domains=None):

        try:

            getattr(nfqueue.payload, 'get_physindev')

            self.mac_indexed_clients = False

        except AttributeError:

            self.mac_indexed_clients = True

        self.data_path = data_path

        self.lease_lifetime = dhcp_lease_lifetime

        self.lease_renewal = dhcp_lease_renewal

        self.dhcp_domain = dhcp_domain

        self.dhcp_server_ip = dhcp_server_ip

        self.ra_period = ra_period

        if dhcp_nameservers is None:

            self.dhcp_nameserver = []

        else:

            self.dhcp_nameservers = dhcp_nameservers

        if ipv6_nameservers is None:

            self.ipv6_nameservers = []

        else:

            self.ipv6_nameservers = ipv6_nameservers

        if dhcpv6_domains is None:

            self.dhcpv6_domains = []

        else:

            self.dhcpv6_domains = dhcpv6_domains

        self.ipv6_enabled = False

        self.clients = {}

        #self.subnets = {}

        #self.ifaces = {}

        #self.v6nets = {}

        self.nfq = {}

        # Inotify setup

        self.wm = pyinotify.WatchManager()

        mask = pyinotify.EventsCodes.ALL_FLAGS["IN_DELETE"]

        mask |= pyinotify.EventsCodes.ALL_FLAGS["IN_CLOSE_WRITE"]

        inotify_handler = ClientFileHandler(self)

        self.notifier = pyinotify.Notifier(self.wm, inotify_handler)

        self.wm.add_watch(self.data_path, mask, rec=True)

        # NFQUEUE setup

        if dhcp_queue_num is not None:

            self._setup_nfqueue(dhcp_queue_num, AF_INET, self.dhcp_response, 0)

        if rs_queue_num is not None:

            self._setup_nfqueue(rs_queue_num, AF_INET6, self.rs_response, 10)

            self.ipv6_enabled = True

        if ns_queue_num is not None:

            self._setup_nfqueue(ns_queue_num, AF_INET6, self.ns_response, 10)

            self.ipv6_enabled = True

        if dhcpv6_queue_num is not None:

            self._setup_nfqueue(dhcpv6_queue_num, AF_INET6, self.dhcpv6_response, 10)

            self.ipv6_enabled = True

    def get_binding(self, ifindex, mac):

        try:

            if self.mac_indexed_clients:

                logging.debug(" - Getting binding for mac %s", mac)

                b = self.clients[mac]

            else:

                logging.debug(" - Getting binding for ifindex %s", ifindex)

                b = self.clients[ifindex]

            return b

        except KeyError:

            logging.debug(" - No client found for mac / ifindex %s / %s",

                          mac, ifindex)

            return None

    def _cleanup(self):

        """ Free all resources for a graceful exit

        """

        logging.info("Cleaning up")

        logging.debug(" - Closing netfilter queues")

        for q, _ in self.nfq.values():

            q.close()

        logging.debug(" - Stopping inotify watches")

        self.notifier.stop()

        logging.info(" - Cleanup finished")

    def _setup_nfqueue(self, queue_num, family, callback, pending):

        logging.info("Setting up NFQUEUE for queue %d, AF %s",

                      queue_num, family)

        q = nfqueue.queue()

        q.set_callback(callback)

        q.fast_open(queue_num, family)

        q.set_queue_maxlen(5000)

        # This is mandatory for the queue to operate

        q.set_mode(nfqueue.NFQNL_COPY_PACKET)

        self.nfq[q.get_fd()] = (q, pending)

        logging.debug(" - Successfully set up NFQUEUE %d", queue_num)

    def build_config(self):

        self.clients.clear()

        for path in glob.glob(os.path.join(self.data_path, "*")):

            self.add_tap(path)

        self.print_clients()

    def get_ifindex(self, iface):

        """ Get the interface index from sysfs

        """

        logging.debug(" - Getting ifindex for interface %s from sysfs", iface)

        path = os.path.abspath(os.path.join(SYSFS_NET, iface, "ifindex"))

        if not path.startswith(SYSFS_NET):

            return None

        ifindex = None

        try:

            f = open(path, 'r')

        except EnvironmentError:

            logging.debug(" - %s is probably down, removing", iface)

            self.remove_tap(iface)

            return ifindex

        try:

            ifindex = f.readline().strip()

            try:

                ifindex = int(ifindex)

            except ValueError, e:

                logging.warn(" - Failed to get ifindex for %s, cannot parse"

                             " sysfs output '%s'", iface, ifindex)

        except EnvironmentError, e:

            logging.warn(" - Error reading %s's ifindex from sysfs: %s",

                         iface, str(e))

            self.remove_tap(iface)

        finally:

            f.close()

        return ifindex

    def get_iface_hw_addr(self, iface):

        """ Get the interface hardware address from sysfs

        """

        logging.debug(" - Getting mac for iface %s", iface)

        path = os.path.abspath(os.path.join(SYSFS_NET, iface, "address"))

        if not path.startswith(SYSFS_NET):

            return None

        addr = None

        try:

            f = open(path, 'r')

        except EnvironmentError:

            logging.debug(" - %s is probably down, removing", iface)

            self.remove_tap(iface)

            return addr

        try:

            addr = f.readline().strip()

        except EnvironmentError, e:

            logging.warn(" - Failed to read hw address for %s from sysfs: %s",

                         iface, str(e))

        finally:

            f.close()

        return addr

    def add_tap(self, path):

        """ Add an interface to monitor

        """

        tap = os.path.basename(path)

        logging.info("Updating configuration for %s", tap)

        b = parse_binding_file(path)

        if b is None:

            return

        ifindex = self.get_ifindex(b.tap)

        if ifindex is None:

            logging.warn(" - Stale configuration for %s found", tap)

        else:

            if b.is_valid():

                if self.mac_indexed_clients:

                    self.clients[b.mac] = b

                else:

                    self.clients[ifindex] = b

                logging.debug(" - Added client:")

                logging.debug(" + %5s: %10s %20s %7s %15s",

                               ifindex, b.hostname, b.mac, b.tap, b.ip)

    def remove_tap(self, tap):

        """ Cleanup clients on a removed interface

        """

        try:

            for k, cl in self.clients.items():

                if cl.tap == tap:

                    logging.info("Removing client %s and closing socket on %s",

                                 cl.hostname, cl.tap)

                    logging.debug(" - %10s | %10s %20s %10s %20s",

                                  k, cl.hostname, cl.mac, cl.tap, cl.ip)

                    cl.socket.close()

                    del self.clients[k]

        except:

            logging.debug("Client on %s disappeared!!!", tap)

    def dhcp_response(self, arg1, arg2=None):  # pylint: disable=W0613,R0914

        """ Generate a reply to bnetfilter-queue-deva BOOTP/DHCP request

        """

        logging.info(" * Processing pending DHCP request")

        # Workaround for supporting both squeezy's nfqueue-bindings-python

        # and wheezy's python-nfqueue because for some reason the function's

        # signature has changed and has broken compatibility

        # See bug http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718894

        if arg2:

            payload = arg2

        else:

            payload = arg1

        # Decode the response - NFQUEUE relays IP packets

        pkt = IP(payload.get_data())

        #logging.debug(pkt.show())

        # Get the client MAC address

        resp = pkt.getlayer(BOOTP).copy()

        hlen = resp.hlen

        mac = resp.chaddr[:hlen].encode("hex")

        mac, _ = re.subn(r'([0-9a-fA-F]{2})', r'\1:', mac, hlen - 1)

        # Server responses are always BOOTREPLYs

        resp.op = "BOOTREPLY"

        del resp.payload

        indev = get_indev(payload)

        binding = self.get_binding(indev, mac)

        if binding is None:

            # We don't know anything about this interface, so accept the packet

            # and return

            logging.debug(" - Ignoring DHCP request on unknown iface %s", indev)

            # We don't know what to do with this packet, so let the kernel

            # handle it

            payload.set_verdict(nfqueue.NF_ACCEPT)

            return

        # Signal the kernel that it shouldn't further process the packet

        payload.set_verdict(nfqueue.NF_DROP)

        if mac != binding.mac:

            logging.warn(" - Recieved spoofed DHCP request: mac %s, indev %s",

                         mac, indev)

            return

        if not binding.ip:

            logging.info(" - No IP found in binding file.")

            return

        logging.info(" - Generating DHCP response:"

                     " host %s, mac %s, tap %s, indev %s",

                       binding.hostname, mac, binding.tap, indev)

        resp = Ether(dst=mac, src=self.get_iface_hw_addr(binding.indev))/\

               IP(src=DHCP_DUMMY_SERVER_IP, dst=binding.ip)/\

               UDP(sport=pkt.dport, dport=pkt.sport)/resp

        subnet = binding.net

        if not DHCP in pkt:

            logging.warn(" - Invalid request from %s on %s, no DHCP"

                         " payload found", binding.mac, binding.tap)

            return

        dhcp_options = []

        requested_addr = binding.ip

        for opt in pkt[DHCP].options:

            if type(opt) is tuple and opt[0] == "message-type":

                req_type = opt[1]

            if type(opt) is tuple and opt[0] == "requested_addr":

                requested_addr = opt[1]

        logging.info(" - %s from %s on %s", DHCP_TYPES.get(req_type, "UNKNOWN"),

                     binding.mac, binding.tap)

        if self.dhcp_domain:

            domainname = self.dhcp_domain

        else:

            domainname = binding.hostname.split('.', 1)[-1]

        if req_type == DHCPREQUEST and requested_addr != binding.ip:

            resp_type = DHCPNAK

            logging.info(" - Sending DHCPNAK to %s on %s: requested %s"

                         " instead of %s", binding.mac, binding.tap,

                         requested_addr, binding.ip)

        elif req_type in (DHCPDISCOVER, DHCPREQUEST):

            resp_type = DHCP_REQRESP[req_type]

            resp.yiaddr = binding.ip

            dhcp_options += [

                 ("hostname", binding.hostname),

                 ("domain", domainname),

                 ("broadcast_address", str(subnet.broadcast)),

                 ("subnet_mask", str(subnet.netmask)),

                 ("renewal_time", self.lease_renewal),

                 ("lease_time", self.lease_lifetime),

            ]

            if subnet.gw:

                dhcp_options += [("router", subnet.gw)]

            dhcp_options += [("name_server", x) for x in self.dhcp_nameservers]

        elif req_type == DHCPINFORM:

            resp_type = DHCP_REQRESP[req_type]

            dhcp_options += [

                 ("hostname", binding.hostname),

                 ("domain", domainname),

            ]

            dhcp_options += [("name_server", x) for x in self.dhcp_nameservers]

        elif req_type == DHCPRELEASE:

            # Log and ignore

            logging.info(" - DHCPRELEASE from %s on %s",

                         binding.hostname, binding.tap)

            return

        # Finally, always add the server identifier and end options

        dhcp_options += [

            ("message-type", resp_type),

            ("server_id", DHCP_DUMMY_SERVER_IP),

            "end"

        ]

        resp /= DHCP(options=dhcp_options)

        logging.info(" - %s to %s (%s) on %s", DHCP_TYPES[resp_type], mac,

                     binding.ip, binding.tap)

        try:

            binding.sendp(resp)

        except socket.error, e:

            logging.warn(" - DHCP response on %s (%s) failed: %s",

                         binding.tap, binding.hostname, str(e))

        except Exception, e:

            logging.warn(" - Unkown error during DHCP response on %s (%s): %s",

                         binding.tap, binding.hostname, str(e))

    def dhcpv6_response(self, arg1, arg2=None):  # pylint: disable=W0613

        logging.info(" * Processing pending DHCPv6 request")

        # Workaround for supporting both squeezy's nfqueue-bindings-python

        # and wheezy's python-nfqueue because for some reason the function's

        # signature has changed and has broken compatibility

        # See bug http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718894

        if arg2:

            payload = arg2

        else:

            payload = arg1

        pkt = IPv6(payload.get_data())

        indev = get_indev(payload)

        #TODO: figure out how to find the src mac

        mac = None

        binding = self.get_binding(indev, mac)

        if binding is None:

            # We don't know anything about this interface, so accept the packet

            # and return

            logging.debug(" - Ignoring dhcpv6 request for mac %s", mac)

            # We don't know what to do with this packet, so let the kernel

            # handle it

            payload.set_verdict(nfqueue.NF_ACCEPT)

            return

        # Signal the kernel that it shouldn't further process the packet

        payload.set_verdict(nfqueue.NF_DROP)

        subnet = binding.net6

        if subnet.net is None:

            logging.debug(" - No IPv6 network assigned for tap %s", binding.tap)

            return

        indevmac = self.get_iface_hw_addr(binding.indev)

        ifll = subnet.make_ll64(indevmac)

        if ifll is None:

            return

        ofll = subnet.make_ll64(binding.mac)

        if ofll is None:

            return

        logging.info(" - Generating DHCPv6 response for host %s (mac %s) on tap %s",

                      binding.hostname, binding.mac, binding.tap)

        if self.dhcpv6_domains:

            domains = self.dhcpv6_domains

        else:

            domains = [binding.hostname.split('.', 1)[-1]]

        # We do this in order not to caclulate optlen ourselves

        dnsdomains = str(DHCP6OptDNSDomains(dnsdomains=domains))

        dnsservers = str(DHCP6OptDNSServers(dnsservers=self.ipv6_nameservers))

        resp = Ether(src=indevmac, dst=binding.mac)/\

               IPv6(tc=192, src=str(ifll), dst=str(ofll))/\

               UDP(sport=pkt.dport, dport=pkt.sport)/\

               DHCP6_Reply(trid=pkt[DHCP6_InfoRequest].trid)/\

               DHCP6OptClientId(duid=pkt[DHCP6OptClientId].duid)/\

               DHCP6OptServerId(duid=DUID_LLT(lladdr=indevmac, timeval=time.time()))/\

               DHCP6OptDNSDomains(dnsdomains)/\

               DHCP6OptDNSServers(dnsservers)

        try:

            binding.sendp(resp)

        except socket.error, e:

            logging.warn(" - DHCPv6 on %s (%s) failed: %s",

                         binding.tap, binding.hostname, str(e))

        except Exception, e:

            logging.warn(" - Unkown error during DHCPv6 on %s (%s): %s",

                         binding.tap, binding.hostname, str(e))

    def rs_response(self, arg1, arg2=None):  # pylint: disable=W0613

        """ Generate a reply to a BOOTP/DHCP request

        """

        logging.info(" * Processing pending RS request")

        # Workaround for supporting both squeezy's nfqueue-bindings-python

        # and wheezy's python-nfqueue because for some reason the function's

        # signature has changed and has broken compatibility

        # See bug http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718894

        if arg2:

            payload = arg2

        else:

            payload = arg1

        pkt = IPv6(payload.get_data())

        #logging.debug(pkt.show())

        try:

            mac = pkt.lladdr

        except:

            logging.debug(" - Cannot obtain lladdr in rs")

            return

        indev = get_indev(payload)

        binding = self.get_binding(indev, mac)

        if binding is None:

            # We don't know anything about this interface, so accept the packet

            # and return

            logging.debug(" - Ignoring router solicitation on for mac %s", mac)

            # We don't know what to do with this packet, so let the kernel

            # handle it

            payload.set_verdict(nfqueue.NF_ACCEPT)

            return

        # Signal the kernel that it shouldn't further process the packet

        payload.set_verdict(nfqueue.NF_DROP)

        if mac != binding.mac:

            logging.warn(" - Received spoofed RS request: mac %s, tap %s",

                         mac, binding.tap)

            return

        subnet = binding.net6

        if subnet.net is None:

            logging.debug(" - No IPv6 network assigned for tap %s", binding.tap)

            return

        indevmac = self.get_iface_hw_addr(binding.indev)

        ifll = subnet.make_ll64(indevmac)

        if ifll is None:

            return

        logging.info(" - Generating RA for host %s (mac %s) on tap %s",

                      binding.hostname, mac, binding.tap)

        resp = Ether(src=indevmac)/\

               IPv6(src=str(ifll))/ICMPv6ND_RA(O=1, routerlifetime=14400)/\

               ICMPv6NDOptPrefixInfo(prefix=str(subnet.prefix),

                                     prefixlen=subnet.prefixlen)

        if self.ipv6_nameservers:

            resp /= ICMPv6NDOptRDNSS(dns=self.ipv6_nameservers,

                                     lifetime=self.ra_period * 3)

        try:

            binding.sendp(resp)

        except socket.error, e:

            logging.warn(" - RA on %s (%s) failed: %s",

                         binding.tap, binding.hostname, str(e))

        except Exception, e:

            logging.warn(" - Unkown error during RA on %s (%s): %s",

                         binding.tap, binding.hostname, str(e))

    def ns_response(self, arg1, arg2=None):  # pylint: disable=W0613

        """ Generate a reply to an ICMPv6 neighbor solicitation

        """

        logging.info(" * Processing pending NS request")

        # Workaround for supporting both squeezy's nfqueue-bindings-python

        # and wheezy's python-nfqueue because for some reason the function's

        # signature has changed and has broken compatibility

        # See bug http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=718894

        if arg2:

            payload = arg2

        else:

            payload = arg1

        ns = IPv6(payload.get_data())

        #logging.debug(ns.show())

        try:

            mac = ns.lladdr

        except:

            logging.debug(" - Cannot obtain lladdr from ns")

            return

        indev = get_indev(payload)

        binding = self.get_binding(indev, mac)

        if binding is None:

            # We don't know anything about this interface, so accept the packet

            # and return

            logging.debug(" - Ignoring neighbour solicitation for eui64 %s",

                          ns.tgt)

            # We don't know what to do with this packet, so let the kernel

            # handle it

            payload.set_verdict(nfqueue.NF_ACCEPT)

            return

        payload.set_verdict(nfqueue.NF_DROP)

        if mac != binding.mac:

            logging.warn(" - Received spoofed NS request"

                         " for mac %s from tap %s", mac, binding.tap)

            return

        subnet = binding.net6

        if subnet.net is None:

            logging.debug(" - No IPv6 network assigned for the interface")

            return

        indevmac = self.get_iface_hw_addr(binding.indev)

        ifll = subnet.make_ll64(indevmac)

        if ifll is None:

            return

        if not (subnet.net.overlaps(ns.tgt) or str(ns.tgt) == str(ifll)):

            logging.debug(" - Received NS for a non-routable IP (%s)", ns.tgt)

            return 1

        logging.info(" - Generating NA for host %s (mac %s) on tap %s",

                     binding.hostname, mac, binding.tap)

        resp = Ether(src=indevmac, dst=binding.mac)/\

               IPv6(src=str(ifll), dst=ns.src)/\

               ICMPv6ND_NA(R=1, O=0, S=1, tgt=ns.tgt)/\

               ICMPv6NDOptDstLLAddr(lladdr=indevmac)

        try:

            binding.sendp(resp)

        except socket.error, e:

            logging.warn(" - NA on %s (%s) failed: %s",

                         binding.tap, binding.hostname, str(e))

        except Exception, e:

            logging.warn(" - Unkown error during periodic NA to %s (%s): %s",

                         binding.tap, binding.hostname, str(e))

    def send_periodic_ra(self):

        # Use a separate thread as this may take a _long_ time with

        # many interfaces and we want to be responsive in the mean time

        threading.Thread(target=self._send_periodic_ra).start()

    def _send_periodic_ra(self):

        logging.info("Sending out periodic RAs")

        start = time.time()

        i = 0

        for binding in self.clients.values():

            tap = binding.tap

            indev = binding.indev

            # mac = binding.mac

            subnet = binding.net6

            if subnet.net is None:

                logging.debug(" - Skipping periodic RA on interface %s,"

                              " as it is not IPv6-connected", tap)

                continue

            indevmac = self.get_iface_hw_addr(indev)

            ifll = subnet.make_ll64(indevmac)

            if ifll is None:

                continue

            resp = Ether(src=indevmac)/\

                   IPv6(src=str(ifll))/ICMPv6ND_RA(routerlifetime=14400)/\

                   ICMPv6NDOptPrefixInfo(prefix=str(subnet.prefix),

                                         prefixlen=subnet.prefixlen)

            if self.ipv6_nameservers:

                resp /= ICMPv6NDOptRDNSS(dns=self.ipv6_nameservers,

                                         lifetime=self.ra_period * 3)

            try:

                binding.sendp(resp)

            except socket.error, e:

                logging.warn(" - Periodic RA on %s (%s) failed: %s",

                             tap, binding.hostname, str(e))

            except Exception, e:

                logging.warn(" - Unkown error during periodic RA on %s (%s):"

                             " %s", tap, binding.hostname, str(e))

            i += 1

        logging.info(" - Sent %d RAs in %.2f seconds", i, time.time() - start)

    def serve(self):

        """ Safely perform the main loop, freeing all resources upon exit

        """

        try:

            self._serve()

        finally:

            self._cleanup()

    def _serve(self):

        """ Loop forever, serving DHCP requests

        """

        self.build_config()