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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright (c) 2015-2023 Savoir-faire Linux Inc.
# Author: Adrien Béraud <adrien.beraud@savoirfairelinux.com>
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
import argparse
import os
import subprocess
from pyroute2 import NDB, NSPopen
def int_range(mini, maxi):
def check_ifnum(arg):
try:
ret = int(arg)
except ValueError:
raise argparse.ArgumentTypeError('must be an integer')
if ret > maxi or ret < mini:
raise argparse.ArgumentTypeError(
f'must be {mini} <= int <= {maxi}'
)
return ret
return check_ifnum
if __name__ == '__main__':
parser = argparse.ArgumentParser(
description='Creates a virtual network topology for testing'
)
parser.add_argument(
'-i', '--ifname', help='interface name', default='ethdht'
)
parser.add_argument(
'-n',
'--ifnum',
type=int_range(1, 245),
help='number of isolated interfaces to create',
default=1,
)
parser.add_argument(
'-r',
'--remove',
help='remove instead of adding network interfaces',
action='store_true',
)
parser.add_argument(
'-l',
'--loss',
help='simulated packet loss (percent)',
type=int,
default=0,
)
parser.add_argument(
'-d', '--delay', help='simulated latency (ms)', type=int, default=0
)
parser.add_argument(
'-4', '--ipv4', help='Enable IPv4', action='store_true'
)
parser.add_argument(
'-6', '--ipv6', help='Enable IPv6', action='store_true'
)
parser.add_argument(
'-b',
'--debug',
help='Turn on debug logging and dump topology databases',
action='store_true',
)
parser.add_argument(
'-v',
'--verbose',
help='Turn on verbose output on netns and interfaces operations',
action='store_true',
)
args = parser.parse_args()
local_addr4 = '10.0.42.'
local_addr6 = '2001:db9::'
bripv4 = f'{local_addr4}1/24'
bripv6 = f'{local_addr6}1/64'
bridge_name = f'br{args.ifname}'
tap_name = f'tap{args.ifname}'
veth_names = []
namespaces = []
ipv4addrs = []
ipv6addrs = []
for ifn in range(args.ifnum):
namespaces.append(f'node{ifn}')
veth_names.append(f'{args.ifname}{ifn}')
ipv4addrs.append(f'{local_addr4}{ifn+8}/24' if args.ipv4 else None)
ipv6addrs.append(f'{local_addr6}{ifn+8}/64' if args.ipv6 else None)
with NDB(log='debug' if args.debug else None) as ndb:
if args.remove:
# cleanup interfaces in the main namespace
for iface in veth_names + [bridge_name] + [tap_name]:
if iface in ndb.interfaces:
ndb.interfaces[iface].remove().commit()
if args.verbose:
print(f'link: del main/{iface}')
# cleanup namespaces
for nsname in namespaces:
try:
ndb.netns[nsname].remove().commit()
if args.verbose:
print(f'netns: del {nsname}')
except KeyError:
pass
else:
# create ports
for veth, nsname, ipv4addr, ipv6addr in zip(
veth_names, namespaces, ipv4addrs, ipv6addrs
):
# create a network namespace and launch NDB for it
#
# another possible solution could be simply to attach
# the namespace to the main NDB instance, but it can
# take a lot of memory in case of many interfaces, thus
# launch and discard netns NDB instances
netns = NDB(
log='debug' if args.debug else None,
sources=[
{
'target': 'localhost',
'netns': nsname,
'kind': 'netns',
}
],
)
if args.verbose:
print(f'netns: add {nsname}')
# create the port and push the peer into the namespace
(
ndb.interfaces.create(
**{
'ifname': veth,
'kind': 'veth',
'state': 'up',
'peer': {'ifname': veth, 'net_ns_fd': nsname},
}
).commit()
)
if args.verbose:
print(f'link: add main/{veth} <-> {nsname}/{veth}')
# bring up namespace's loopback
(
netns.interfaces.wait(ifname='lo', timeout=3)
.set('state', 'up')
.commit()
)
if args.verbose:
print(f'link: set {nsname}/lo')
# bring up the peer
with netns.interfaces.wait(ifname=veth, timeout=3) as i:
i.set('state', 'up')
if args.ipv4:
i.add_ip(ipv4addr)
if args.ipv6:
i.add_ip(ipv6addr)
if args.verbose:
print(f'link: set {nsname}/{veth}, {ipv4addr}, {ipv6addr}')
# disconnect the namespace NDB agent, not removing the NS
if args.debug:
fname = f'{nsname}-ndb.db'
print(f'dump: netns topology database {fname}')
netns.schema.backup(fname)
netns.close()
# set up the emulation QDisc
nsp = NSPopen(
nsname,
[
'tc',
'qdisc',
'add',
'dev',
veth,
'root',
'netem',
'delay',
f'{args.delay}ms',
f'{int(args.delay)/2}ms',
'loss',
f'{args.loss}%',
'25%',
],
stdout=subprocess.PIPE,
)
nsp.communicate()
nsp.wait()
nsp.release()
if args.verbose:
print(
f'netem: add {nsname}/{veth}, '
f'{args.delay}, {args.loss}'
)
# create the tap
#
# for some reason we should create the tap inteface first,
# and only then bring it up, thus two commit() calls
(
ndb.interfaces.create(
kind='tuntap', ifname=tap_name, mode='tap'
)
.commit()
.set('state', 'up')
.commit()
)
if args.verbose:
print(f'link: add main/{tap_name}')
# create the bridge and add all the ports
with ndb.interfaces.create(
ifname=bridge_name, kind='bridge', state='up'
) as i:
if args.ipv4:
i.add_ip(bripv4)
if args.ipv6:
i.add_ip(bripv6)
for iface in veth_names + [tap_name]:
i.add_port(iface)
if args.verbose:
print(f'link: add main/{bridge_name}, {bripv4}, {bripv6}')
with open(os.devnull, 'w') as fnull:
if args.ipv4:
subprocess.call(
[
'sysctl',
'-w',
f'net.ipv4.conf.{bridge_name}.forwarding=1',
],
stdout=fnull,
)
if args.verbose:
print(f'sysctl: set {bridge_name} ipv4 forwarding')
if args.ipv6:
subprocess.call(
[
'sysctl',
'-w',
f'net.ipv6.conf.{bridge_name}.forwarding=1',
],
stdout=fnull,
)
if args.verbose:
print(f'sysctl: set {bridge_name} ipv4 forwarding')
if args.debug:
fname = 'main-ndb.db'
print('dump: the main netns topology database')
ndb.schema.backup(fname)
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