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2021-01-24 19:51:48 +01:00
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import itertools
import ipaddress
import logging
import atexit
import socket
import time
import threading
import subprocess
import pyroute2
from pyroute2.netlink.rtnl import rtypes
import docker
from flask import request, jsonify
from . import interface
from . import NetDhcpError, udhcpc, app
LIBRARY = 'IPR'
OPTS_KEY = 'com.docker.network.generic'
OPT_BRIDGE = 'bridge'
OPT_IPV6 = 'ipv6'
logger = logging.getLogger('net-dhcp')
interface.InitializeLibrary(LIBRARY)
client = docker.from_env()
@atexit.register
def close_docker():
client.close()
gateway_hints = {}
container_dhcp_clients = {}
@atexit.register
def cleanup_dhcp():
for endpoint, dhcp in container_dhcp_clients.items():
logger.warning('cleaning up orphaned container DHCP client (endpoint "%s")', endpoint)
dhcp.stop()
def veth_pair(e):
return f'dh-{e[:12]}', f'{e[:12]}-dh'
def iface_addrs(iface):
return list(map(lambda a: ipaddress.ip_interface((a['address'], a['prefixlen'])), iface.ipaddr))
def iface_nets(iface):
return list(map(lambda n: n.network, iface_addrs(iface)))
def get_bridges():
reserved_nets = set(map(ipaddress.ip_network, map(lambda c: c['Subnet'], \
itertools.chain.from_iterable(map(lambda i: i['Config'], filter(lambda i: i['Driver'] != 'net-dhcp', \
map(lambda n: n.attrs['IPAM'], client.networks.list())))))))
return dict(map(lambda i: (i['ifname'], i), filter(lambda i: i['kind'] == 'bridge' and not \
set(iface_nets(i)).intersection(reserved_nets), map(lambda i: interface.GetInterface(LIBRARY, i['ifname']), \
interface.GetInterfaces(LIBRARY)))))
def net_bridge(n):
return interface.GetInterface(LIBRARY, client.networks.get(n).attrs['Options'][OPT_BRIDGE])
def ipv6_enabled(n):
options = client.networks.get(n).attrs['Options']
return OPT_IPV6 in options and options[OPT_IPV6] == 'true'
def endpoint_container_iface(n, e):
for cid, info in client.networks.get(n).attrs['Containers'].items():
if info['EndpointID'] == e:
container = client.containers.get(cid)
netns = f'/proc/{container.attrs["State"]["Pid"]}/ns/net'
with pyroute2.NetNS(netns) as rtnl:
for link in rtnl.get_links():
attrs = dict(link['attrs'])
if attrs['IFLA_ADDRESS'] == info['MacAddress']:
return {
'netns': netns,
'ifname': attrs['IFLA_IFNAME'],
'address': attrs['IFLA_ADDRESS']
}
break
return None
def await_endpoint_container_iface(n, e, timeout=5):
start = time.time()
iface = None
while time.time() - start < timeout:
try:
iface = endpoint_container_iface(n, e)
except docker.errors.NotFound:
time.sleep(0.5)
if not iface:
raise NetDhcpError('Timed out waiting for container to become availabile')
return iface
def endpoint_container_hostname(n, e):
for cid, info in client.networks.get(n).attrs['Containers'].items():
if info['EndpointID'] == e:
return client.containers.get(cid).attrs['Config']['Hostname']
return None
@app.route('/NetworkDriver.GetCapabilities', methods=['POST'])
def net_get_capabilities():
return jsonify({
'Scope': 'local',
'ConnectivityScope': 'global'
})
@app.route('/NetworkDriver.CreateNetwork', methods=['POST'])
def create_net():
req = request.get_json(force=True)
for data in req['IPv4Data']:
if data['AddressSpace'] != 'null' or data['Pool'] != '0.0.0.0/0':
return jsonify({'Err': 'Only the null IPAM driver is supported'}), 400
options = req['Options'][OPTS_KEY]
if OPT_BRIDGE not in options:
return jsonify({'Err': 'No bridge provided'}), 400
# We have to use a custom "enable IPv6" option because Docker's null IPAM driver doesn't support IPv6 and a plugin
# IPAM driver isn't allowed to return an empty address
if OPT_IPV6 in options and options[OPT_IPV6] not in ('', 'true', 'false'):
return jsonify({'Err': 'Invalid boolean value for ipv6'}), 400
desired = options[OPT_BRIDGE]
bridges = get_bridges()
if desired not in bridges:
return jsonify({'Err': f'Bridge "{desired}" not found (or the specified bridge is already used by Docker)'}), 400
logger.info('Creating network "%s" (using bridge "%s")', req['NetworkID'], desired)
return jsonify({})
@app.route('/NetworkDriver.DeleteNetwork', methods=['POST'])
def delete_net():
return jsonify({})
@app.route('/NetworkDriver.CreateEndpoint', methods=['POST'])
def create_endpoint():
req = request.get_json(force=True)
network_id = req['NetworkID']
endpoint_id = req['EndpointID']
req_iface = req['Interface']
bridge = net_bridge(network_id)
bridge_addrs = iface_addrs(bridge)
if_host, if_container = veth_pair(endpoint_id)
logger.info('creating veth pair %s <=> %s', if_host, if_container)
if_host = interface.CreateInterface(LIBRARY, if_host, 'veth', if_container)
if_host.up()
try:
start = time.time()
while isinstance(if_container, str) and time.time() - start < 10:
try:
if_container = interface.GetInterface(LIBRARY, if_container)
if_container.up()
except KeyError:
time.sleep(0.5)
if isinstance(if_container, str):
raise NetDhcpError(f'timed out waiting for {if_container} to appear in host')
interface.AddPort(LIBRARY, bridge.ifname, if_host.ifname)
res_iface = {
'MacAddress': '',
'Address': '',
'AddressIPv6': ''
}
# !!!
# if 'MacAddress' in req_iface and req_iface['MacAddress']:
# (if_container
# .set('address', req_iface['MacAddress'])
# .commit())
# else:
# res_iface['MacAddress'] = if_container['address']
# !!!
res_iface['MacAddress'] = if_container['address']
def try_addr(type_):
addr = None
k = 'AddressIPv6' if type_ == 'v6' else 'Address'
if k in req_iface and req_iface[k]:
# TODO: Should we allow static IP's somehow?
# Just validate the address, Docker will add it to the interface for us
#addr = ipaddress.ip_interface(req_iface[k])
#for bridge_addr in bridge_addrs:
# if addr.ip == bridge_addr.ip:
# raise NetDhcpError(400, f'Address {addr} is already in use on bridge {bridge["ifname"]}')
raise NetDhcpError('Only the null IPAM driver is supported')
else:
dhcp = udhcpc.DHCPClient(if_container, v6=type_ == 'v6', once=True)
addr = dhcp.finish()
if not addr:
return
res_iface[k] = str(addr)
if dhcp.gateway:
gateway_hints[endpoint_id] = dhcp.gateway
logger.info('Adding IP%s address %s to %s', type_, addr, if_container['ifname'])
try_addr('v4')
if ipv6_enabled(network_id):
try_addr('v6')
res = jsonify({
'Interface': res_iface
})
except Exception as e:
logger.exception(e)
if not isinstance(if_container, str):
interface.DelPort(LIBRARY, bridge.ifname, if_host.ifname)
interface.RemoveInterface(LIBRARY, if_host.ifname)
if isinstance(e, NetDhcpError):
res = jsonify({'Err': str(e)}), e.status
else:
res = jsonify({'Err': str(e)}), 500
finally:
return res
@app.route('/NetworkDriver.EndpointOperInfo', methods=['POST'])
def endpoint_info():
req = request.get_json(force=True)
bridge = net_bridge(req['NetworkID'])
if_host, _if_container = veth_pair(req['EndpointID'])
if_host = interface.GetInterface(LIBRARY, if_host)
return jsonify({
'bridge': bridge['ifname'],
'if_host': {
'name': if_host['ifname'],
'mac': if_host['address']
}
})
@app.route('/NetworkDriver.DeleteEndpoint', methods=['POST'])
def delete_endpoint():
req = request.get_json(force=True)
bridge = net_bridge(req['NetworkID'])
if_host, _if_container = veth_pair(req['EndpointID'])
if_host = interface.GetInterface(LIBRARY, if_host)
interface.DelPort(LIBRARY, bridge.ifname, if_host.ifname)
interface.RemoveInterface(LIBRARY, if_host.ifname)
return jsonify({})
@app.route('/NetworkDriver.Join', methods=['POST'])
def join():
req = request.get_json(force=True)
network = req['NetworkID']
endpoint = req['EndpointID']
bridge = net_bridge(req['NetworkID'])
_if_host, if_container = veth_pair(req['EndpointID'])
res = {
'InterfaceName': {
'SrcName': if_container,
'DstPrefix': bridge['ifname']
},
'StaticRoutes': []
}
if endpoint in gateway_hints:
gateway = gateway_hints[endpoint]
logger.info('Setting IPv4 gateway from DHCP (%s)', gateway)
res['Gateway'] = str(gateway)
del gateway_hints[endpoint]
ipv6 = ipv6_enabled(network)
for route in bridge.routes:
if route['type'] != rtypes['RTN_UNICAST'] or \
(route['family'] == socket.AF_INET6 and not ipv6):
continue
if route['dst'] in ('', '/0'):
if route['family'] == socket.AF_INET and 'Gateway' not in res:
logger.info('Adding IPv4 gateway %s', route['gateway'])
res['Gateway'] = route['gateway']
elif route['family'] == socket.AF_INET6 and 'GatewayIPv6' not in res:
logger.info('Adding IPv6 gateway %s', route['gateway'])
res['GatewayIPv6'] = route['gateway']
elif route['gateway']:
dst = f'{route["dst"]}/{route["dst_len"]}'
logger.info('Adding route to %s via %s', dst, route['gateway'])
res['StaticRoutes'].append({
'Destination': dst,
'RouteType': 0,
'NextHop': route['gateway']
})
container_dhcp_clients[endpoint] = ContainerDHCPManager(network, endpoint)
return jsonify(res)
@app.route('/NetworkDriver.Leave', methods=['POST'])
def leave():
req = request.get_json(force=True)
endpoint = req['EndpointID']
if endpoint in container_dhcp_clients:
container_dhcp_clients[endpoint].stop()
del container_dhcp_clients[endpoint]
return jsonify({})
# Trying to grab the container's attributes (to get the network namespace)
# will deadlock (since Docker is waiting on us), so we must defer starting
# the DHCP client
class ContainerDHCPManager:
def __init__(self, network, endpoint):
self.network = network
self.endpoint = endpoint
self.ipv6 = ipv6_enabled(network)
self.dhcp = None
self.dhcp6 = None
self._thread = threading.Thread(target=self.run)
self._thread.start()
def _on_event(self, dhcp, event_type, _event):
if event_type != udhcpc.EventType.RENEW or not dhcp.gateway:
return
logger.info('[dhcp container] Replacing gateway with %s', dhcp.gateway)
subprocess.check_call(['nsenter', f'-n{dhcp.netns}', '--', '/sbin/ip', 'route', 'replace', 'default', 'via',
str(dhcp.gateway)], timeout=1, stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
stderr=subprocess.DEVNULL)
# TODO: Adding default route with NDB seems to be broken (because of the dst syntax?)
#for route in ndb.routes:
# if route['type'] != rtypes['RTN_UNICAST'] or \
# route['oif'] != dhcp.iface['index'] or \
# (route['family'] == socket.AF_INET6 and not self.ipv6) or \
# route['dst'] not in ('', '/0'):
# continue
# # Needed because Route.remove() doesn't like a blank destination
# logger.info('Removing default route via %s', route['gateway'])
# route['dst'] = '::' if route['family'] == socket.AF_INET6 else '0.0.0.0'
# (route
# .remove()
# .commit())
#logger.info('Adding default route via %s', dhcp.gateway)
#(ndb.routes.add({'oif': dhcp.iface['index'], 'gateway': dhcp.gateway})
# .commit())
def run(self):
try:
iface = await_endpoint_container_iface(self.network, self.endpoint)
hostname = endpoint_container_hostname(self.network, self.endpoint)
self.dhcp = udhcpc.DHCPClient(iface, event_listener=self._on_event, hostname=hostname)
logger.info('Starting DHCPv4 client on %s in container namespace %s', iface['ifname'], \
self.dhcp.netns)
if self.ipv6:
self.dhcp6 = udhcpc.DHCPClient(iface, v6=True, event_listener=self._on_event, hostname=hostname)
logger.info('Starting DHCPv6 client on %s in container namespace %s', iface['ifname'], \
self.dhcp6.netns)
except Exception as e:
logger.exception(e)
if self.dhcp:
self.dhcp.finish(timeout=1)
def stop(self):
if not self.dhcp:
return
try:
logger.info('Shutting down DHCPv4 client on %s in container namespace %s', \
self.dhcp.iface['ifname'], self.dhcp.netns)
self.dhcp.finish(timeout=1)
finally:
try:
if self.ipv6:
logger.info('Shutting down DHCPv6 client on %s in container namespace %s', \
self.dhcp6.iface['ifname'], self.dhcp.netns)
self.dhcp6.finish(timeout=1)
finally:
self._thread.join()
# we have to do this since the docker client leaks sockets...
global client
client.close()
client = docker.from_env()