Use gateway from DHCP

net-dhcp/network.py

@@ -27,6 +27,17 @@ client = docker.from_env()
 def close_docker():
     client.close()
 
+host_dhcp_clients = {}
+container_dhcp_clients = {}
+@atexit.register
+def cleanup_dhcp():
+    for endpoint, dhcp in host_dhcp_clients.items():
+        logger.warning('cleaning up orphaned host DHCP client (endpoint "%s")', endpoint)
+        dhcp.finish(timeout=1)
+    for endpoint, dhcp in container_dhcp_clients.items():
+        logger.warning('cleaning up orphaned container DHCP client (endpoint "%s")', endpoint)
+        dhcp.finish(timeout=1)
+
 def veth_pair(e):
     return f'dh-{e[:12]}', f'{e[:12]}-dh'
 
@@ -114,10 +125,10 @@ def create_endpoint():
                     if addr.ip == bridge_addr.ip:
                         raise NetDhcpError(400, f'Address {addr} is already in use on bridge {bridge["ifname"]}')
             elif type_ == 'v4':
-                dhcp = udhcpc.DHCPClient(if_container['ifname'], once=True)
+                dhcp = udhcpc.DHCPClient(if_container['ifname'])
-                dhcp.finish()
+                addr = dhcp.await_ip(timeout=10)
-                addr = dhcp.ip
                 res_iface['Address'] = str(addr)
+                host_dhcp_clients[req['EndpointID']] = dhcp
             else:
                 raise NetDhcpError(400, f'DHCPv6 is currently unsupported')
             logger.info('Adding address %s to %s', addr, if_container['ifname'])
@@ -180,6 +191,7 @@ def delete_endpoint():
 @app.route('/NetworkDriver.Join', methods=['POST'])
 def join():
     req = request.get_json(force=True)
+    endpoint = req['EndpointID']
 
     bridge = net_bridge(req['NetworkID'])
     _if_host, if_container = veth_pair(req['EndpointID'])
@@ -191,6 +203,13 @@ def join():
         },
         'StaticRoutes': []
     }
+    if endpoint in host_dhcp_clients:
+        dhcp = host_dhcp_clients[endpoint]
+        logger.info('Setting IPv4 gateway from DHCP (%s)', dhcp.gateway)
+        res['Gateway'] = str(dhcp.gateway)
+        dhcp.finish(timeout=1)
+        del host_dhcp_clients[endpoint]
+
     ipv6 = ipv6_enabled(req['NetworkID'])
     for route in bridge.routes:
         if route['type'] != rtypes['RTN_UNICAST'] or (route['family'] == socket.AF_INET6 and not ipv6):

net-dhcp/udhcpc.py

@@ -1,6 +1,7 @@
 from enum import Enum
 import ipaddress
 from os import path
+import time
 import threading
 import subprocess
 import logging
@@ -9,6 +10,7 @@ from pyroute2.netns.process.proxy import NSPopen
 
 INFO_PREFIX = '__info'
 HANDLER_SCRIPT = path.join(path.dirname(__file__), 'udhcpc_handler.py')
+AWAIT_INTERVAL = 0.1
 
 class EventType(Enum):
     BOUND = 'bound'
@@ -62,12 +64,22 @@ class DHCPClient:
             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):
+    def await_ip(self, timeout=5):
+        # TODO: this bad
+        waited = 0
+        while not self.ip:
+            if waited >= timeout:
+                raise DHCPClientError('Timed out waiting for dhcp lease')
+            time.sleep(AWAIT_INTERVAL)
+            waited += AWAIT_INTERVAL
+        return self.ip
+
+    def finish(self, timeout=5):
         if not self.once:
             self.proc.terminate()
-        if self.proc.wait(timeout=10) != 0:
+        if self.proc.wait(timeout=timeout) != 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')
+            raise DHCPClientError(f'Timed out waiting for dhcp lease')