#!/usr/bin/python
+import os.path
import sys
import pydhcplib
import pydhcplib.dhcp_network
from threading import Thread
from subprocess import PIPE, Popen
import netifaces as ni
+sys.path.append('/usr/lib/xen-default/lib/python/')
+from xen.lowlevel import xs
import syslog as s
dhcp_options = {'domain_name_server': ','.join(config.dhcp.dns),
'ip_address_lease_time': config.dhcp.get('leasetime', 60*60*24)}
+class Interfaces(object):
+ @staticmethod
+ def primary_ip(name):
+ """primary_ip returns an interface's primary IP address.
+
+ This is the first IPv4 address returned by "ip addr show $name"
+ """
+ # TODO(quentin): The netifaces module is a pile of crappy C.
+ # Figure out a way to do this in native Python.
+ return ni.ifaddresses(name)[ni.AF_INET][0]['addr']
+
+ @staticmethod
+ def exists(name):
+ """exists checks if an interface exists.
+
+ Args:
+ name: Interface name
+ """
+ return os.path.exists("/sys/class/net/"+name)
+
+
class DhcpBackend:
def __init__(self, queue):
database.connect()
self.queue = queue
+ self.main_ip = Interfaces.primary_ip(config.xen.iface)
+ def add_route_and_arp(self, ip, intf, gateway):
+ try:
+ p = Popen(['ip', 'route', 'add', ip, 'dev', intf, 'src', self.main_ip, 'metric', '2' if intf.startswith('vif') else '1'], stdout=PIPE, stderr=PIPE)
+ (out, err) = p.communicate()
+ if p.returncode == 0:
+ s.syslog(s.LOG_INFO, "Added route for IP %s to interface %s" % (ip, intf))
+ self.queue.put((ip, gateway))
+ sys.stderr.write(err)
+ sys.stdout.write(out)
+ except Exception as e:
+ s.syslog(s.LOG_ERR, "Could not add route for IP %s: %s" % (ip, e))
def findNIC(self, mac):
database.clear_cache()
return database.NIC.query.filter_by(mac_addr=mac).first()
if parts[1] == ipstr:
s.syslog(s.LOG_DEBUG, "find_interface found "+str(nic.ip)+" on "+parts[0])
return parts[0]
+ # Either the machine isn't running, or the route is missing. We can
+ # fix the latter.
+ try:
+ xsc = xs.xs()
+ domid = xsc.read('', '/vm/%s/device/vif/0/frontend-id' % (nic.machine.uuid))
+ # If we didn't find the domid, the machine is either off or the
+ # UUID in xenstore isn't right. Try slightly harder.
+ if not domid:
+ for uuid in xsc.ls('', '/vm'):
+ if xsc.read('', '/vm/%s/name' % (uuid)) == 'd_' + nic.machine.name:
+ domid = xsc.read('', '/vm/%s/device/vif/0/frontend-id' % (uuid))
+ if not domid:
+ xsc.close()
+ return None
+ for vifnum in xsc.ls('', '/local/domain/0/backend/vif/%s' % (domid)):
+ if xsc.read('', '/local/domain/0/backend/vif/%s/%s/mac' % (domid, vifnum)) == nic.mac_addr:
+ # Prefer the tap if it exists; paravirtualized HVMs will
+ # have already unplugged it, so if it's there, it's the one
+ # in use.
+ for viftype in ('tap', 'vif'):
+ vif = '%s%s.%s' % (viftype, domid, vifnum)
+ if Interfaces.exists(vif):
+ self.add_route_and_arp(nic.ip, vif, nic.gateway)
+ xsc.close()
+ return vif
+ xsc.close()
+ except Exception as e:
+ try:
+ xsc.close()
+ except Exception as e2:
+ s.syslog(s.LOG_ERR, "Could not close connection to xenstore: %s" % (e2))
+ s.syslog(s.LOG_ERR, "Could not find interface and add missing route: %s" % (e))
return None
def getParameters(self, **extra):
s.syslog(s.LOG_INFO,"Ack ip "+str(yiaddr)+" for "+str(chaddr))
n = self.findNIC(str(chaddr))
intf = self.find_interface_by_nic(n)
- main_ip = ni.ifaddresses(config.xen.iface)[ni.AF_INET][0]['addr']
s.syslog(s.LOG_ERR, "Interface is %s" % (intf))
# Don't perform "other" actions if the machine isn't running
other_action = n.other_action if n.other_action and intf else ''
# IP needs to be added. Just try adding both of them, and
# arp for whichever of them turns out to be new.
for parms in [(n.ip, n.gateway), (n.other_ip, n.other_gateway)]:
- try:
- p = Popen(['ip', 'route', 'add', parms[0], 'dev', intf, 'src', main_ip, 'metric', '2' if intf.startswith('vif') else '1'], stdout=PIPE, stderr=PIPE)
- (out, err) = p.communicate()
- if p.returncode == 0:
- s.syslog(s.LOG_INFO, "Added route for IP %s to interface %s" % (parms[0], intf))
- self.queue.put(parms)
- sys.stderr.write(err)
- sys.stdout.write(out)
- except Exception as e:
- s.syslog(s.LOG_ERR, "Could not add route for IP %s: %s" % (parms[0], e))
+ self.add_route_and_arp(parms[0], intf, parms[1])
try:
# iptables will let you add the same rule again and again;
# let's not do that.
# We went through the DISCOVER codepath already to populate some
# of the packet's parameters. If we renumbered the VM just above,
# the packet is set to offer them what they asked for - the old
- # address. So, we'll send then a DHCPNACK and they'll come right
+ # address. So, we'll send them a DHCPNACK and they'll come right
# back and be offered the new address. The code above won't be
# able to add duplicate routes, won't insert a duplicate DNAT,
# and won't ARP again because the routes will exist, so this won't
while True:
(ip, gw) = self.queue.get()
try:
- p = Popen(['timeout', '5', 'arpspoof', '-i', self.iface, '-t', gw, ip], stdout=PIPE, stderr=PIPE)
+ p = Popen(['timeout', '-s', 'KILL', '5', 'arpspoof', '-i', self.iface, '-t', gw, ip], stdout=PIPE, stderr=PIPE)
(out, err) = p.communicate()
if p.returncode != 124:
s.syslog(s.LOG_ERR, "arpspoof returned %s for IP %s gateway %s" % (p.returncode, ip, gw))