nm-dispatcher: dispatch on reapply

Trigger a dispatcher event when a connection is reapplied on a NM device.
Some devices such as phones have already a DHCP client running for accepting
connections when they are plugged into USB to transfer data over SSH.
When NetworkManager switches the connection IP method to shared,
it spawns a dnsmasq process to handle DHCP and DNS for that connection.
However, a dispatcher event is needed to disable the external DHCP server
for these USB connections as NetworkManager's dnsmasq handles them now.
Moreover, when the connection method is switched to a different mode,
the external DHCP server needs to be spawned again to make sure that
SSH connections are still possible to the device.

To achieve this, add a new NetworkManager Dispatcher event
'reapply' which is triggered when a connection is reapplied on a NM
device. This way, a dispatcher script can handle the case above by
inspecting the IP method in the dispatcher script.

src/core/devices/nm-device.c

@@ -13041,6 +13041,10 @@ check_and_reapply_connection(NMDevice            *self,
     if (priv->state >= NM_DEVICE_STATE_ACTIVATED)
         nm_device_update_metered(self);
 
+    /* Notify dispatcher when re-applied */
+    _LOGD(LOGD_DEVICE, "Notifying re-apply complete");
+    nm_dispatcher_call_device(NM_DISPATCHER_ACTION_REAPPLY, self, NULL, NULL, NULL, NULL);
+
     return TRUE;
 }
 

src/core/nm-dispatcher.c

@@ -468,7 +468,8 @@ static const char *action_table[] = {[NM_DISPATCHER_ACTION_HOSTNAME]      = NMD_
                                      [NM_DISPATCHER_ACTION_DHCP_CHANGE_4] = NMD_ACTION_DHCP4_CHANGE,
                                      [NM_DISPATCHER_ACTION_DHCP_CHANGE_6] = NMD_ACTION_DHCP6_CHANGE,
                                      [NM_DISPATCHER_ACTION_CONNECTIVITY_CHANGE] =
-                                         NMD_ACTION_CONNECTIVITY_CHANGE};
+                                         NMD_ACTION_CONNECTIVITY_CHANGE,
+                                     [NM_DISPATCHER_ACTION_REAPPLY] = NMD_ACTION_REAPPLY};
 
 static const char *
 action_to_string(NMDispatcherAction action)

src/core/nm-dispatcher.h

@@ -21,7 +21,8 @@ typedef enum {
     NM_DISPATCHER_ACTION_VPN_DOWN,
     NM_DISPATCHER_ACTION_DHCP_CHANGE_4,
     NM_DISPATCHER_ACTION_DHCP_CHANGE_6,
-    NM_DISPATCHER_ACTION_CONNECTIVITY_CHANGE
+    NM_DISPATCHER_ACTION_CONNECTIVITY_CHANGE,
+    NM_DISPATCHER_ACTION_REAPPLY,
 } NMDispatcherAction;
 
 #define NM_DISPATCHER_ACTION_DHCP_CHANGE_X(IS_IPv4) \

src/libnm-core-aux-extern/nm-dispatcher-api.h

@@ -33,6 +33,7 @@
 #define NMD_ACTION_DHCP4_CHANGE        "dhcp4-change"
 #define NMD_ACTION_DHCP6_CHANGE        "dhcp6-change"
 #define NMD_ACTION_CONNECTIVITY_CHANGE "connectivity-change"
+#define NMD_ACTION_REAPPLY             "reapply"
 
 typedef enum {
     DISPATCH_RESULT_UNKNOWN     = 0,