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"""Bridge control utilities.
"""
import os
import os.path
import re
import sys
from xen.xend import XendRoot
xroot = XendRoot.instance()
os.defpath = os.defpath + ':/sbin:/usr/sbin:/usr/local/sbin'
CMD_IFCONFIG = 'ifconfig'
CMD_ROUTE = 'route'
CMD_BRCTL = 'brctl'
CMD_IPTABLES = "iptables"
DEFAULT_BRIDGE = 'nbe-br'
DEFAULT_INTERFACE = 'eth0'
opts = None
class Opts:
def __init__(self, defaults):
for (k, v) in defaults.items():
setattr(self, k, v)
pass
def cmd(p, s):
"""Print and execute command 'p' with args 's'.
"""
global opts
c = p + ' ' + s
if opts.verbose: print c
if not opts.dryrun:
os.system(c)
def default_bridge():
return xroot.get_config_value('bridge', DEFAULT_BRIDGE)
def default_interface():
return xroot.get_config_value('interface', DEFAULT_INTERFACE)
def vif_dev(dom, vif):
"""Return the name of the network interface for vif on domain dom.
"""
return "vif%d.%d" % (dom, vif)
def vif_bridge_add(dom, vif, bridge=None):
"""Add the network interface for vif on dom to a bridge.
"""
if not bridge: bridge = default_bridge()
d = { 'bridge': bridge, 'vif': vif_dev(dom, vif) }
cmd(CMD_BRCTL, 'addif %(bridge)s %(vif)s' % d)
return bridge
def vif_bridge_rem(dom, vif, bridge=None):
"""Remove the network interface for vif on dom from a bridge.
"""
if not bridge: bridge = default_bridge()
print 'vif_bridge_rem>', dom, vif, bridge
d = { 'bridge': bridge, 'vif': vif_dev(dom, vif) }
cmd(CMD_BRCTL, 'delif %(bridge)s %(vif)s' % d)
def vif_restrict_addr(dom, vif, addr, delete=0):
d = { 'vif': vif_dev(dom, vif), 'addr': addr}
if delete:
d['flag'] = '-D'
else:
d['flag'] = '-A'
cmd(CMD_IPTABLES, '-P FORWARD DROP')
cmd(CMD_IPTABLES, '%(flag)s FORWARD -m physdev --physdev-in %(vif)s -s %(addr)s -j ACCEPT' % d)
cmd(CMD_IPTABLES, '%(flag)s FORWARD -m physdev --physdev-out %(vif)s -d %(addr)s -j ACCEPT' % d)
def bridge_create(bridge=None, **kwd):
"""Create a bridge.
Defaults hello time to 0, forward delay to 0 and stp off.
"""
if not bridge: bridge = default_bridge()
cmd(CMD_BRCTL, 'addbr %s' % bridge)
if kwd.get('hello', None) is None:
kwd['hello'] = 0
if kwd.get('fd', None) is None:
kwd['fd'] = 0
if kwd.get('stp', None) is None:
kwd['stp'] = 'off'
bridge_set(bridge, **kwd)
def bridge_set(bridge, hello=None, fd=None, stp=None):
"""Set bridge parameters.
"""
if hello is not None:
cmd(CMD_BRCTL, 'sethello %s %d' % (bridge, hello))
if fd is not None:
cmd(CMD_BRCTL, 'setfd %s %d' % (bridge, fd))
if stp is not None:
cmd(CMD_BRCTL, 'stp %s %s' % (bridge, stp))
def bridge_del(bridge=None):
"""Delete a bridge.
"""
if not bridge: bridge = default_bridge()
cmd(CMD_BRCTL, 'delbr %s' % bridge)
def routes():
"""Return a list of the routes.
"""
fin = os.popen(CMD_ROUTE + ' -n', 'r')
routes = []
for x in fin:
if x.startswith('Kernel'): continue
if x.startswith('Destination'): continue
x = x.strip()
y = x.split()
z = { 'destination': y[0],
'gateway' : y[1],
'mask' : y[2],
'flags' : y[3],
'metric' : y[4],
'ref' : y[5],
'use' : y[6],
'interface' : y[7] }
routes.append(z)
return routes
def ifconfig(interface):
"""Return the ip config for an interface,
"""
fin = os.popen(CMD_IFCONFIG + ' %s' % interface, 'r')
inetre = re.compile('\s*inet\s*addr:(?P<address>\S*)\s*Bcast:(?P<broadcast>\S*)\s*Mask:(?P<mask>\S*)')
info = None
for x in fin:
m = inetre.match(x)
if not m: continue
info = m.groupdict()
info['interface'] = interface
break
return info
def reconfigure(interface=None, bridge=None):
"""Reconfigure an interface to be attached to a bridge, and give the bridge
the IP address etc. from interface. Move the default route to the interface
to the bridge.
If opts.create is true, creates the bridge.
"""
global opts
if not interface: interface = default_interface()
if not bridge: bridge = default_bridge()
intf_info = ifconfig(interface)
if not intf_info:
print 'Interface not found:', interface
return
if opts.create:
bridge_create(bridge)
#bridge_info = ifconfig(bridge)
#if not bridge_info:
# print 'Bridge not found:', bridge
# return
route_info = routes()
intf_info['bridge'] = bridge
intf_info['gateway'] = None
for r in route_info:
if (r['destination'] == '0.0.0.0' and
'G' in r['flags'] and
r['interface'] == interface):
intf_info['gateway'] = r['gateway']
if not intf_info['gateway']:
print 'Gateway not found: ', interface
return
cmd(CMD_IFCONFIG,
'%(bridge)s %(address)s netmask %(mask)s broadcast %(broadcast)s up'
% intf_info)
cmd(CMD_ROUTE,
'add default gateway %(gateway)s dev %(bridge)s'
% intf_info)
cmd(CMD_BRCTL, 'addif %(bridge)s %(interface)s' % intf_info)
cmd(CMD_IFCONFIG, '%(interface)s 0.0.0.0' % intf_info)
defaults = {
'interface': default_interface(),
'bridge' : default_bridge(),
'verbose' : 1,
'dryrun' : 0,
'create' : 0,
}
opts = Opts(defaults)
def set_opts(val):
global opts
opts = val
return opts
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