Fix `NSPopen` proxy leaks

net-dhcp/network.py

@@ -324,9 +324,12 @@ class ContainerDHCPManager:
 
         logger.info('[dhcp container] Replacing gateway with %s', dhcp.gateway)
         proc = NSPopen(dhcp.netns, ['/sbin/ip', 'route', 'replace', 'default', 'via', str(dhcp.gateway)])
-        if proc.wait(timeout=1) != 0:
-            raise NetDhcpError(f'Failed to replace default route; "ip route" command exited with non-zero code %d', \
-                proc.returncode)
+        try:
+            if proc.wait(timeout=1) != 0:
+                raise NetDhcpError(f'Failed to replace default route; "ip route" command exited with non-zero code %d', \
+                    proc.returncode)
+        finally:
+            proc.release()
 
         # TODO: Adding default route with NDB seems to be broken (because of the dst syntax?)
         #for route in ndb.routes:
@@ -362,6 +365,8 @@ class ContainerDHCPManager:
                     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:

net-dhcp/udhcpc.py

@@ -126,21 +126,23 @@ class DHCPClient:
         if self._shutdown_event.is_set():
             return
 
-        if self.proc.returncode is not None and (not self.once or self.proc.returncode != 0):
-            raise DHCPClientError(f'udhcpc{self._suffix} exited early with code {self.proc.returncode}')
-        if self.once:
-            self.await_ip()
-        else:
-            self.proc.terminate()
-
-        if self.proc.wait(timeout=timeout) != 0:
-            raise DHCPClientError(f'udhcpc{self._suffix} exited with non-zero exit code {self.proc.returncode}')
-        if self.netns:
-            self.proc.release()
-
-        self._shutdown_event.set()
-        self._event_thread.join()
-        self._event_queue.close()
-        self._event_queue.unlink()
+        try:
+            if self.proc.returncode is not None and (not self.once or self.proc.returncode != 0):
+                raise DHCPClientError(f'udhcpc{self._suffix} exited early with code {self.proc.returncode}')
+            if self.once:
+                self.await_ip()
+            else:
+                self.proc.terminate()
 
-        return self.ip
+            if self.proc.wait(timeout=timeout) != 0:
+                raise DHCPClientError(f'udhcpc{self._suffix} exited with non-zero exit code {self.proc.returncode}')
+
+            return self.ip
+        finally:
+            if self.netns:
+                self.proc.release()
+
+            self._shutdown_event.set()
+            self._event_thread.join()
+            self._event_queue.close()
+            self._event_queue.unlink()