cloudstack/vnet/sbindir/cloud-vn.in

#!/usr/bin/env python
#  -*- mode: python; -*-
#============================================================================
# Copyright (C) 2005, 2006 Mike Wray <mike.wray@hp.com>
#
# This library is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
#
# This library 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
#============================================================================

# Vnet (network virtualization) control utility.

import os
import os.path
import re
import socket
import sys
sys.path.insert(0,"@PYTHONDIR@")
from getopt import getopt, GetoptError

#from xen.xend import sxp
#from xen.xend.PrettyPrint import prettyprint
import cloud_sxp as sxp
from cloud_PrettyPrint import prettyprint

# Path of unix-domain socket to vnetd.
VNETD_PATH = "/tmp/vnetd"

def vnetd_running():
    return os.path.exists(VNETD_PATH)

def vnetd_open():
    sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
    sock.connect(VNETD_PATH)
    fi = sock.makefile('r', 0)
    fo = sock.makefile('w', 0)
    return (fi, fo)

os.defpath += ':/sbin:/usr/sbin:/usr/local/sbin'
CMD_IFCONFIG = 'ifconfig'
CMD_BRCTL    = 'brctl'

opts = None

class Opts:

    def __init__(self, **kwds):
        for (k, v) in kwds.items():
            setattr(self, k, v)

opts = Opts(verbose=False, dryrun=False)

def set_opts(val):
    global opts
    opts = val
    return opts

def cmd(prog, *args):
    """Execute command 'prog' with 'args', optionally printing the command.
    """
    global opts
    command = " ".join([ prog ] + map(str, args))
    if opts.verbose:
        print command
    if not opts.dryrun:
        os.system(command)

def vif_bridge_add(bridge, vif):
    """Add a network interface to a bridge.
    """
    cmd(CMD_BRCTL, 'addif', bridge, vif)

def vif_bridge_rem(bridge, vif):
    """Remove a network interface from a bridge.
    """
    cmd(CMD_BRCTL, 'delif', bridge, vif)

def bridge_create(bridge, **kwd):
    """Create a bridge.
    Defaults hello time to 0, forward delay to 0 and stp off.
    """
    cmd(CMD_BRCTL, 'addbr', 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)
    cmd(CMD_IFCONFIG, bridge, "up")

def bridge_set(bridge, hello=None, fd=None, stp=None):
    """Set bridge parameters.
    """
    if hello is not None:
        cmd(CMD_BRCTL, 'sethello', bridge, hello)
    if fd is not None:
        cmd(CMD_BRCTL, 'setfd', bridge, fd)
    if stp is not None:
        cmd(CMD_BRCTL, 'stp', bridge, stp)

def bridge_del(bridge):
    """Delete a bridge.
    """
    cmd(CMD_IFCONFIG, bridge, 'down')
    cmd(CMD_BRCTL, 'delbr', bridge)

class Bridge:
    # Network interfaces are at /sys/class/net/*.
    # A bridge interface has ./bridge dir, ./brif is dir of bridged interfaces
    # (symlinks to the brport dirs).
    # If an interface is bridged ./brport is bridged port info,
    # brport/bridge is a symlink to the bridge.

    INTERFACE_DIR = "/sys/class/net"

    def isBridge(klass, dev):
        """Test if a network interface is a bridge.
        """
        devdir = os.path.join(klass.INTERFACE_DIR, dev)
        brdir = os.path.join(devdir, "bridge")
        try:
            os.stat(brdir)
            return True
        except:
            return False

    isBridge = classmethod(isBridge)

    def getInterfaces(klass):
        """Get a list of the network interfaces.
        """
        try:
            v = os.listdir(klass.INTERFACE_DIR)
            v.sort()
            return v
        except:
            return []

    getInterfaces = classmethod(getInterfaces)

    def getInterfaceAddr(klass, intf):
        intfdir = os.path.join(klass.INTERFACE_DIR, intf)
        addrfile = os.path.join(intfdir, "address")
        try:
            f = file(addrfile, "rb")
        except Exception, ex:
            #print ex
            return None
        try:
            return f.readline().strip()
        finally:
            f.close()

    getInterfaceAddr = classmethod(getInterfaceAddr)

    def getBridges(klass):
        """Get a list of the bridges.
        """
        return [ dev for dev in klass.getInterfaces() if klass.isBridge(dev) ]

    getBridges = classmethod(getBridges)

    def getBridgeInterfaces(klass, dev):
        """Get a list of the interfaces attached to a bridge.
        """
        devdir = os.path.join(klass.INTERFACE_DIR, dev)
        intfdir = os.path.join(devdir, "brif")
        try:
            v = os.listdir(intfdir)
            v.sort()
            return v
        except:
            return []

    getBridgeInterfaces = classmethod(getBridgeInterfaces)

    def getBridge(klass, dev):
        """Get the bridge an interface is attached to (if any).
        """
        devdir = os.path.join(klass.INTERFACE_DIR, dev)
        brfile = os.path.join(devdir, "brport/bridge")
        try:
            brpath = os.readlink(brfile)
            return os.path.basename(brpath)
        except:
            return None

    getBridge = classmethod(getBridge)

def vnet_cmd(expr):
    """Send a command expression to the vnet implementation.
    """
    if vnetd_running():
        (fi, fo) = vnetd_open()
    else:
        fi = None
        fo = file("/proc/vnet/policy", "wb")
    try:
        sxp.show(expr, fo)
        fo.flush()
    finally:
        if fi: fi.close()
        if fo: fo.close()

def varp_flush():
    """Flush the varp cache.
    """
    expr = ['varp.flush']
    return vnet_cmd(expr)

def vif_add(vnetid, vmac):
    """Tell the vnet implementation to add a vif to a vnet.
    """
    expr = ['vif.add', ['vnet', vnetid], ['vmac', vmac]]
    return vnet_cmd(expr)

def vif_del(vnetid, vmac):
    """Tell the vnet implementation to delete a vif from a vnet.
    """
    expr = ['vif.del', ['vnet', vnetid], ['vmac', vmac]]
    return vnet_cmd(expr)

def vnet_add(vnetid, vnetif=None, security=None):
    """Tell the vnet implementation to add a vnet.
    """
    expr = ['vnet.add', ['id', vnetid]]
    if vnetif:
        expr.append(['vnetif', vnetif])
    if security:
        expr.append(['security', security])
    return vnet_cmd(expr)

def peer_add(addr, port=None):
    expr = ['peer.add', ['addr', addr]]
    if port:
        expr.append(['port', port])
    return vnet_cmd(expr)
    
def peer_del(addr, port=None):
    expr = ['peer.del', ['addr', addr]]
    return vnet_cmd(expr)

def vnet_del(vnetid):
    """Tell the vnet implementation to delete a vnet.
    """
    expr = ['vnet.del', ['id', vnetid]]
    return vnet_cmd(expr)

def vnet_create(vnetid, vnetif=None, bridge=None, security=None):
    """Tell the vnet implementation to add a vnet.
    If 'bridge' is non-null, create the bridge and add the vnet interface
    to it.
    """
    vnet_add(vnetid, vnetif=vnetif, security=security)
    val = vnet_lookup(vnetid)
    if not vnetif:
        vnetif = sxp.child_value(val, "vnetif")
    vmac = get_mac(vnetif)
    emac = get_mac("eth0") or get_mac("eth1") or get_mac("eth2")
    if emac and vmac != emac:
        set_mac(vnetif, emac)
    cmd(CMD_IFCONFIG, vnetif, 'up')
    if bridge:
        bridge_create(bridge)
        vif_bridge_add(bridge, vnetif)
    return val
        
def vnet_delete(vnet, delbridge=False):
    """Tell the vnet implementation to delete a vnet.
    If the vnet interface is attached to a bridge,
    remove it from the bridge, and if delbridge is true
    delete the bridge.
    """
    v = vnet_lookup(vnet)    
    if not v:
        raise GetoptError("vnet not found: %s" % vnet)
    vnetid = sxp.child_value(v, "id")
    vnetif = sxp.child_value(v, "vnetif")
    bridge = Bridge.getBridge(vnetif)
    if bridge:
        vif_bridge_rem(bridge, vnetif)
        if delbridge:
            bridge_del(bridge)
    return vnet_del(vnetid)

def get_mac(intf):
    """Get the mac address of an interface.
    """
    try:
        return Bridge.getInterfaceAddr(intf)
    except:
        pass

    hwre = re.compile(".*\s+HWaddr\s+(?P<mac>\S*)\s+.*")
    fin = os.popen("%s %s" % (CMD_IFCONFIG, intf), 'r')
    try:
        for x in fin:
            m = hwre.match(x)
            if not m:
                continue
            info = m.groupdict()
            return info['mac']
        return None
    finally:
        fin.close()

def set_mac(intf, mac):
    cmd(CMD_IFCONFIG, intf, 'down')
    cmd(CMD_IFCONFIG, intf, 'hw', 'ether', mac)
    cmd(CMD_IFCONFIG, intf, 'up')

def get_addr(host):
    return socket.gethostbyname(host)

def get_port(srv):
    return srv

def vnetidof(v):
    """Normalise a vnet id. Adds leading 0 fields to make up 8 if
    there aren't enough. Pads all fields to 4 hex digits.
    """
    try:
        l = v.split(":")
        l = [ int(x or 0, 16) for x in l ]
        l = [ 0 ] * (8 - len(l)) + l
        return ":".join([ "%04x" % x for x in l ])
    except:
        return None

def vnet_lookup(vnet, vnets=None):
    """Find the vnet with the given vnet id or vnet interface.

    @param vnet id or interface
    @param vnets list of vnet info to use (get from implementation if None)
    @return vnet info or None if not found
    """
    vnetid = vnetidof(vnet)
    if vnets is None:
        vnets = vnet_list()
    for v in vnets:
        vid = sxp.child_value(v, "id")
        if vid == vnet or vid == vnetid:
            return v
        if sxp.child_value(v, "vnetif") == vnet:
            return v
    return None

def get_vnetid(vnet):
    """Get the normalised vnet id of the given vnet id or vnet interface.
    Raises an error if the vnet cannot be found.
    """
    v = vnet_lookup(vnet)
    if not v:
        raise GetoptError("vnet not found: %s" % vnet)
    vnetid = sxp.child_value(v, "id")
    return vnetid

def vif_list():
    """Get the list of vif info from the vnet implementation.
    """
    if vnetd_running():
        (fi, fo) = vnetd_open()
        sxp.show(['vif.list'], fo)
        fo.flush()
    else:
        fi = file("/proc/vnet/vifs")
        fo = None
    try:
        return sxp.parse(fi) or []
    finally:
        if fi: fi.close()
        if fo: fo.close()

def vnets_filter(vnetlist, vnets):
    """Filter a list of vnet info by a list of vnet ids or interfaces.
    """
    if vnets is None:
        val = vnetlist
    else:
        val = []
        for x in vnets:
            v = vnet_lookup(x, vnets=vnetlist)
            if not v:
                continue
            val.append(v)
    return val

def vnet_list(vnets=None):
    """Get the list of vnet info from the vnet implementation,
    sorted by vnet id.

    @param vnets list of vnet ids or interfaces to filter the results by
    """
    if vnetd_running():
        (fi, fo) = vnetd_open()
        sxp.show(['vnet.list'], fo)
        fo.flush()
    else:
        fi = file("/proc/vnet/vnets")
        fo = None
    try:
        val = vnets_filter(sxp.parse(fi) or [], vnets)
        val.sort(lambda x, y:
                   cmp(sxp.child_value(x, "id"),
                       sxp.child_value(y, "id")))
        return val
    finally:
        if fi: fi.close()
        if fo: fo.close()
        
def vnif_list(vnets=None):
    """Get the list of vnet interface names from the vnet implementation.

    @param vnets list of vnet ids or interfaces to filter the results by
    """
    vnifs = []
    for v in vnet_list(vnets=vnets):
        vnetif = sxp.child_value(v, "vnetif")
        if vnetif:
            vnifs.append(vnetif)
    return vnifs
        
def varp_list():
    """Get the list of varp info from the vnet implementation.
    """
    if vnetd_running():
        (fi, fo) = vnetd_open()
        sxp.show(['varp.list'], fo)
        fo.flush()
    else:
        fi = file("/proc/vnet/varp")
        fo = None
    try:
        return sxp.parse(fi) or []
    finally:
        if fi: fi.close()
        if fo: fo.close()

def peer_list():
    if vnetd_running():
        (fi, fo) = vnetd_open()
        sxp.show(['peer.list'], fo)
        fo.flush()
    else:
        fi = file("/proc/vnet/peers")
        fo = None
    try:
        return sxp.parse(fi) or []
    finally:
        if fi: fi.close()
        if fo: fo.close()

class Opt:
    """Declares command-line options for a command.
    """

    def getopt(klass, argv, opts, args):
        """Get options and args from argv.
        The value opts in the return value has an attribute for
        eacho option or arg. The value args in the return value
        is the remaining arguments.

        @param argv arguments
        @param opts option specifiers (list of Opt objects)
        @param args arg specififiers (list of Arg objects)
        @return (opts, args)
        """
        shortopts = "".join([ x.optShort() for x in opts ])
        longopts  = [ x.optLong() for x in opts ]
        (ovals, oargs) = getopt(argv[1:], shortopts, longopts)
        odir = Opts()
        for x in opts:
            x.setDefault(odir)
        for (k, v) in ovals:
            for x in opts:
                x.setOpt(k, v, odir)
        argc = len(oargs)
        if len(oargs) < len(args):
            raise GetoptError("insufficient arguments for %s" % argv[0])
        for (x, v) in zip(args, oargs):
            x.setArg(v, odir)
        return (odir, oargs[len(args): ])

    getopt = classmethod(getopt)

    def gethelp(klass, opts, args):
        l = []
        for x in opts:
            l.append(x.help())
        for x in args:
            l.append(x.help())
        return " ".join(l)

    gethelp = classmethod(gethelp)

    """A command=-line option.

    @param name option name (this attribute is set to value in opts)
    @param short short option flag (single-character string)
    @param long long option name (defaults to option name, pass "" to suppress)
    @param arg argument name (option has no arg if not specified)
    """
    def __init__(self, name, short=None, long=None, arg=False):
        self.name = name
        self.short = short
        if long is None:
            long = name
        elif not long:
            long = None
        self.long = long
        self.arg = arg

    def help(self):
        s = self.keyShort()
        l = self.keyLong()
        if s and l:
            return "[%s | %s]" % (s, l)
        else:
            return s or l

    def keyShort(self):
        if self.short:
            return "-%s" % self.short
        else:
            return None

    def keyLong(self):
        if self.long:
            return "--%s" % self.long
        else:
            return None

    def optLong(self):
        if not self.long:
            return None
        if self.arg:
            return "%s=" % self.long
        else:
            return self.long

    def optShort(self):
        if not self.short:
            return None
        if self.arg:
            return "%s:" % self.short
        else:
            return self.short

    def setDefault(self, vals):
        if self.arg:
            setattr(vals, self.name, None)
        else:
            setattr(vals, self.name, False)

    def setOpt(self, k, v, vals):
        if k in [ self.keyShort(), self.keyLong() ]:
            if self.arg:
                setattr(vals, self.name, v)
            else:
                if v not in [ None, '' ]:
                    raise GetoptError("option %s does not take an argument" % k)
                setattr(vals, self.name, True)

class Arg:

    """A command-line parameter. Args get their values from arguments
    left over after option processing and are assigned in order.
    The value is accessible as the attribute called 'name' in opts.

    @param name argument name
    """
    def __init__(self, name):
        self.name = name

    def setArg(self, v, vals):
        setattr(vals, self.name, v)

    def help(self):
        return "<%s>" % self.name
            
class VnMain:

    """Methods beginning with this prefix are commands.
    They must all have arguments like this:

    op_foo(self, argv, args, opts)

    argv: original command-line arguments
    args: arguments left after option processing
    opts: option and arg values (accessible as attributes)

    Method options are specified by setting attribute
    .opts on the method to a list of Option objects.
    For args set .args to a list of Arg objects.
    Use .use for short usage string, .help for long help.

    Each option or arg defines an attribute in opts. For example
    an option with name 'foo' is accessible as 'opts.foo'.
    """
    opPrefix = "op_"

    def __init__(self, argv):
        if argv:
            self.name = argv[0]
        else:
            self.name = "vn"
        self.argv = argv
        self.argc = len(argv)

    def error(self, v):
        print >>sys.stderr, "%s: %s" % (self.name, v)
        sys.exit(1)
        
    def getFunction(self, opname):
        key = self.opPrefix + opname.replace("-", "_")
        fn = getattr(self, key, None)
        if not fn:
            raise ValueError("unknown command: %s" % opname)
        return fn
    
    def main(self):
        if self.argc < 2:
            args = ["help"]
        else:
            args = self.argv[1:]
        try:
            fn = self.getFunction(args[0])
        except ValueError, ex:
            self.error(ex)
        try:
            fnopts = self.getOpts(fn)
            fnargs = self.getArgs(fn)
            (opts, parms) = Opt.getopt(args, fnopts, fnargs)
            return fn(args, parms, opts)
        except GetoptError, ex:
            self.error(ex)
        except ValueError, ex:
            self.error(ex)
        except Exception, ex:
            import traceback; traceback.print_exc()
            self.error(ex)

    def getOpts(self, meth):
        return getattr(meth, "opts", [])
    
    def getArgs(self, meth):
        return getattr(meth, "args", [])
    
    def getUse(self, meth):
        return getattr(meth, "use", "")
    
    def getHelp(self, meth):
        return getattr(meth, "help", "") or self.getUse(meth)

    def fnHelp(self, meth):
        return Opt.gethelp(self.getOpts(meth), self.getArgs(meth))

    def printHelp(self, fn, opt_long):
        meth = getattr(self, fn)
        opname = fn[len(self.opPrefix):].replace("_", "-")
        if opt_long:
            help = self.getHelp(meth)
            print "\n  %s" % opname
            if help:
                print "%s" % help
        else:
            use = self.getUse(meth)
            print "  %s %s" % (opname, self.fnHelp(meth))
            if use:
                print "\t\t%s" % use

    def show_vnif(self, dev):
        cmd(CMD_IFCONFIG, dev)
        bridge = Bridge.getBridge(dev)
        if bridge:
            print "          Bridge:", bridge
            interfaces = Bridge.getBridgeInterfaces(bridge)
            if dev in interfaces:
                interfaces.remove(dev)
            if interfaces:
                print "          Interfaces:", ", ".join(interfaces)
            print

    def op_help(self, argv, args, opts):
        if opts.long:
            print '%s <command> <options>' % self.name
            print self.long_help
        else:
            print '%s:' % self.name
        l = dir(self)
        l.sort()
        for fn in l:
            if fn.startswith(self.opPrefix):
                self.printHelp(fn, opts.long)
        print

    op_help.opts = [ Opt('long', short='l') ]

    def op_vnets(self, argv, args, opts):
        vnets = vnet_list(vnets=args or None)
        for v in vnets:
            prettyprint(v, width=50)
            print
            if not opts.long:
                continue
            vnif = sxp.child_value(v, "vnetif")
            if not vnif:
                continue
            self.show_vnif(vnif)
        if opts.all:
            vnetids = {}
            for v in vnets:
                vnetids[sxp.child_value(v, "id")] = v
            for v in vif_list():
                vnet = sxp.child_value(v, "vnet")
                if vnet not in vnetids:
                    continue
                prettyprint(v)
                print
            for v in varp_list():
                prettyprint(v)
                print

    op_vnets.opts = [ Opt('all', short='a'), Opt('long', short='l') ]

    def op_vnifs(self, argv, args, opts):
        vnifs = vnif_list(vnets=args or None)
        for vnif in vnifs:
            self.show_vnif(vnif)

    def op_vifs(self, argv, args, opts):
        for v in vif_list():
            prettyprint(v)
            print

    def op_varp(self, argv, args, opts):
        for v in varp_list():
            prettyprint(v)
            print

    def op_varp_flush(self, argv, args, opts):
        varp_flush()

    def op_vnet_create(self, argv, args, opts):
        return vnet_create(opts.vnet,
                           vnetif=opts.vnetif,
                           bridge=opts.bridge,
                           security=opts.security)

    op_vnet_create.args = [ Arg('vnet') ]
    op_vnet_create.opts = [ Opt('security', short='s', arg="SECURITY"),
                            Opt('bridge', short='b', arg="BRIDGE"),
                            Opt('vnetif', short='v', arg="VNETIF") ]

    def op_vnet_delete(self, argv, args, opts):
        vnetid = get_vnetid(opts.vnet)
        return vnet_delete(vnetid, delbridge=opts.bridge)

    op_vnet_delete.args = [ Arg('vnet') ]
    op_vnet_delete.opts = [ Opt('bridge', short='b') ]

    def op_vif_add(self, argv, args, opts):
        vnetid = get_vnetid(opts.vnet)
        if opts.interface:
            vmac = get_mac(opts.vmac)
            if not vmac:
                raise ValueError("interface not found: %s" % opts.vmac)
        else:
            vmac = opts.vmac
        return vif_add(vnetid, vmac)

    op_vif_add.args = [ Arg('vnet'), Arg('vmac') ]
    op_vif_add.opts = [ Opt('interface', short='i') ]

    def op_vif_delete(self, argv, args, opts):
        vnetid = get_vnetid(opts.vnet)
        if opts.interface:
            vmac = get_mac(opts.vmac)
        else:
            vmac = opts.vmac
        return vif_del(vnetid, vmac)

    op_vif_delete.args = [ Arg('vnet'), Arg('vmac') ]
    op_vif_delete.opts = [ Opt('interface', short='i') ]

    def op_peer_add(self, argv, args, opts):
        addr = get_addr(opts.addr)
        if(opts.port):
            port = get_port(opts.port)
        else:
            port = None
        return peer_add(addr, port)
        
    op_peer_add.args = [ Arg('addr') ]
    op_peer_add.opts = [ Opt('port', short='p') ]
    
    def op_peer_delete(self, argv, args, opts):
        addr = get_addr(opts.addr)
        return peer_del(addr)

    op_peer_delete.args = [ Arg('addr') ]
    
    def op_peers(self, argv, args, opts):
        for v in peer_list():
            prettyprint(v)
            print

    def op_bridges(self, argv, args, opts):
        if opts.long:
            for bridge in Bridge.getBridges():
                cmd(CMD_IFCONFIG, bridge)
                interfaces = Bridge.getBridgeInterfaces(bridge)
                if interfaces:
                    print "          Interfaces:", ", ".join(interfaces)
                    print
        else:
            for bridge in Bridge.getBridges():
                print bridge,
                interfaces = Bridge.getBridgeInterfaces(bridge)
                if interfaces:
                    print ":", ", ".join(interfaces)
                else:
                    print
            
    op_bridges.opts = [ Opt('long', short='l') ]

    def op_insmod(self, argv, args, opts):
        """Insert the vnet kernel module."""
        """cmd("/etc/xen/scripts/vnet-insert", *args)"""

    long_help          = """Control utility for vnets (virtual networking).
Report bugs to Mike Wray <mike.wray@hp.com>.
"""

    op_help.use        = "Print help."
    op_help.help       = "Print help, long help if the option -l or --long is given."

    op_vnets.use       = """Print vnets."""
    op_vnets.help      = """Print vnet information, where options are:
    -a, -all           Print vnets, vifs and varp info.
    -l, --long         Print ifconfigs for vnet interfaces."""

    op_vifs.use        = "Print vifs."

    op_vnifs.use       = "Print ifconfigs for vnet network interfaces."

    op_varp.use        = "Print varp info and entries in the varp cache."

    op_varp_flush.use  = "Flush the varp cache."
    
    op_vnet_create.use = "Create a vnet."

    op_vnet_delete.use = "Delete a vnet."
    op_vnet_delete.help = """Delete a vnet.
    -b, --bridge       Delete the bridge the vnet interface is attached to.
    """

    op_vif_add.use     = "Add a vif to a vnet."
    op_vif_add.help    = """Add a vif to a vnet. Not usually needed as vifs
are added automatically.
    -i, --interface    The vmac is the name of an interface to get the mac from."""

    op_vif_delete.use  = "Delete a vif from a vnet."
    op_vif_delete.help = """Delete a vif from a vnet. Not usually needed as vifs
are removed periodically.
    -i, --interface    The vmac is the name of an interface to get the mac from."""

    op_peer_add.use    = "Add a peer."
    op_peer_add.help   = """Add a peer: <addr> <port>
Vnets use multicast to discover interfaces, but networks are often configured
not to forward multicast. Vnets forward multicasts to peers using UDP.
Only add peers if multicasts are not working, check with

ping -b 224.10.0.1

Only add peers at one machine in a subnet, otherwise you may cause forwarding
loops.
"""

    op_peer_delete.use = "Delete a peer."
    op_peer_delete.help= "Delete a peer: <addr>"

    op_peers.use       = "List peers."
    op_peers.help      = "List peers."

    op_bridges.use     = "Print bridges."

    op_insmod.use      = "Insert the vnet kernel module, optionally with parameters."

if __name__ == "__main__":
    vn = VnMain(sys.argv)
    vn.main()