Initial DHCP functionality

Dockerfile

@@ -3,7 +3,7 @@ FROM python:3-alpine
 COPY requirements.txt /opt/
 RUN pip install -r /opt/requirements.txt
 
-RUN mkdir -p /opt/plugin /run/docker/plugins
+RUN mkdir -p /opt/plugin /run/docker/plugins /var/run/docker/netns
 COPY net-dhcp/ /opt/plugin/net_dhcp
 COPY plugin.sh /opt/plugin/launch.sh
 

Makefile

@@ -28,7 +28,8 @@ create:
 
 debug:
 	@docker run --rm -ti --cap-add CAP_SYS_ADMIN --network host --volume /run/docker/plugins:/run/docker/plugins \
-		--volume /run/docker.sock:/run/docker.sock ${PLUGIN_NAME}:rootfs
+		--volume /run/docker.sock:/run/docker.sock --volume /var/run/docker/netns:/var/run/docker/netns \
+		${PLUGIN_NAME}:rootfs
 
 enable:
 	@echo "### enable plugin ${PLUGIN_NAME}:${PLUGIN_TAG}"		

config.json

@@ -19,6 +19,14 @@
             "options": [
                 "bind"
             ]
+        },
+        {
+            "source": "/var/run/docker/netns",
+            "destination": "/var/run/docker/netns",
+            "type": "bind",
+            "options": [
+                "bind"
+            ]
         }
     ],
     "linux": {

net-dhcp/network.py

@@ -9,7 +9,7 @@ from pyroute2.netlink.rtnl import rtypes
 import docker
 from flask import request, jsonify
 
-from . import NetDhcpError, app
+from . import NetDhcpError, udhcpc, app
 
 OPTS_KEY = 'com.docker.network.generic'
 OPT_PREFIX = 'devplayer0.net-dhcp'
@@ -45,6 +45,8 @@ def get_bridges():
 
 def net_bridge(n):
     return ndb.interfaces[client.networks.get(n).attrs['Options'][OPT_BRIDGE]]
+def ipv6_enabled(n):
+    return client.networks.get(n).attrs['EnableIPv6']
 
 @app.route('/NetworkDriver.GetCapabilities', methods=['POST'])
 def net_get_capabilities():
@@ -88,6 +90,10 @@ def create_endpoint():
     if_container = (ndb.interfaces[if_container]
                     .set('state', 'up')
                     .commit())
+    (bridge
+        .add_port(if_host)
+        .commit())
+
     res_iface = {
         'MacAddress': '',
         'Address': '',
@@ -107,31 +113,36 @@ def create_endpoint():
                 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"]}')
-
-                logger.info('Adding address %s to %s', addr, if_container['ifname'])
             elif type_ == 'v4':
-                raise NetDhcpError(400, f'DHCP{type_} is currently unsupported')
-        try_addr('v4')
-        try_addr('v6')
+                dhcp = udhcpc.DHCPClient(if_container['ifname'], once=True)
+                dhcp.finish()
+                addr = dhcp.ip
+                res_iface['Address'] = str(addr)
+            else:
+                raise NetDhcpError(400, f'DHCPv6 is currently unsupported')
+            logger.info('Adding address %s to %s', addr, if_container['ifname'])
 
-        (bridge
-            .add_port(if_host)
-            .commit())
+        try_addr('v4')
+        if ipv6_enabled(req['NetworkID']):
+            try_addr('v6')
 
         res = jsonify({
             'Interface': res_iface
         })
-    except NetDhcpError as e:
-        (if_host
-            .remove()
-            .commit())
-        logger.error(e)
-        res = jsonify({'Err': str(e)}), e.status
     except Exception as e:
+        logger.exception(e)
+
+        (bridge
+            .del_port(if_host)
+            .commit())
         (if_host
             .remove()
             .commit())
-        res = jsonify({'Err': str(e)}), 500
+
+        if isinstance(e, NetDhcpError):
+            res = jsonify({'Err': str(e)}), e.status
+        else:
+            res = jsonify({'Err': str(e)}), 500
     finally:
         return res
 
@@ -180,8 +191,9 @@ def join():
         },
         'StaticRoutes': []
     }
+    ipv6 = ipv6_enabled(req['NetworkID'])
     for route in bridge.routes:
-        if route['type'] != rtypes['RTN_UNICAST']:
+        if route['type'] != rtypes['RTN_UNICAST'] or (route['family'] == socket.AF_INET6 and not ipv6):
             continue
 
         if route['dst'] == '' or route['dst'] == '/0':

net-dhcp/udhcpc.py

@@ -0,0 +1,73 @@
+from enum import Enum
+import ipaddress
+from os import path
+import threading
+import subprocess
+import logging
+
+from pyroute2.netns.process.proxy import NSPopen
+
+INFO_PREFIX = '__info'
+HANDLER_SCRIPT = path.join(path.dirname(__file__), 'udhcpc_handler.py')
+
+class EventType(Enum):
+    BOUND = 'bound'
+    RENEW = 'renew'
+
+logger = logging.getLogger('gunicorn.error')
+
+class DHCPClientError(Exception):
+    pass
+
+def _nspopen_wrapper(netns):
+    return lambda *args, **kwargs: NSPopen(netns, *args, **kwargs)
+class DHCPClient:
+    def __init__(self, iface, netns=None, once=False, event_listener=lambda t, ip, gw, dom: None):
+        self.netns = netns
+        self.iface = iface
+        self.once = once
+        self.event_listener = event_listener
+
+        Popen = _nspopen_wrapper(netns) if netns else subprocess.Popen
+        cmdline = ['/sbin/udhcpc', '-s', HANDLER_SCRIPT, '-i', iface, '-f']
+        cmdline.append('-q' if once else '-R')
+        self.proc = Popen(cmdline, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, encoding='utf-8')
+
+        self.ip = None
+        self.gateway = None
+        self.domain = None
+        self._event_thread = threading.Thread(target=self._read_events)
+        self._event_thread.start()
+
+    def _read_events(self):
+        while True:
+            line = self.proc.stdout.readline()
+            if not line:
+                break
+            if not line.startswith(INFO_PREFIX):
+                logger.debug('[udhcpc] %s', line)
+                continue
+
+            args = line.split(' ')[1:]
+            try:
+                event_type = EventType(args[0])
+            except ValueError:
+                logger.warning('udhcpc unknown event "%s"', ' '.join(args))
+                continue
+
+            self.ip = ipaddress.ip_interface(args[1])
+            self.gateway = ipaddress.ip_address(args[2])
+            self.domain = args[3]
+
+            logger.debug('[udhcp event] %s %s %s %s', event_type, self.ip, self.gateway, self.domain)
+            self.event_listener(event_type, self.ip, self.gateway, self.domain)
+
+    def finish(self):
+        if not self.once:
+            self.proc.terminate()
+        if self.proc.wait(timeout=10) != 0:
+            raise DHCPClientError(f'udhcpc exited with non-zero exit code {self.proc.returncode}')
+        self._event_thread.join()
+
+        if self.once and not self.ip:
+            raise DHCPClientError(f'failed to obtain lease')

net-dhcp/udhcpc_handler.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+import sys
+from os import environ as env
+
+INFO_PREFIX = '__info'
+
+if __name__ != '__main__':
+    print('You shouldn\'t be importing this script!')
+    sys.exit(1)
+
+event_type = sys.argv[1]
+if event_type == 'bound' or event_type == 'renew':
+    print(f'{INFO_PREFIX} {event_type} {env["ip"]}/{env["mask"]} {env["router"]} {env["domain"]}')
+elif event_type == 'deconfig':
+    print('udhcpc startup / lost lease')
+elif event_type == 'leasefail':
+    print('udhcpc failed to get a lease')
+elif event_type == 'nak':
+    print('udhcpc received NAK')
+else:
+    print(f'unknown udhcpc event "{event_type}"')
+    sys.exit(1)