[PATCH 09/45] vpn: Add VPN agent use callback for plugins

Add callback that can be used by the VPN plugins to tell the vpn_driver
whether it uses VPN agent or not. Default to using VPN agent if the
function is not defined.

This is done to accommodate the state transition in vpn-provider when
the VPN does not utilize VPN agent.
---
 vpn/plugins/vpn.c  | 22 ++++++++++++++++++++++
 vpn/plugins/vpn.h  |  1 +
 vpn/vpn-provider.h |  1 +
 3 files changed, 24 insertions(+)

diff --git a/vpn/plugins/vpn.c b/vpn/plugins/vpn.c
index 52f7cac7..2f87cf04 100644
--- a/vpn/plugins/vpn.c
+++ b/vpn/plugins/vpn.c
@@ -800,6 +800,27 @@ static int vpn_route_env_parse(struct vpn_provider *provider, const char *key,
 	return 0;
 }
 
+static bool vpn_uses_vpn_agent(struct vpn_provider *provider)
+{
+	struct vpn_driver_data *vpn_driver_data = NULL;
+	const char *name = NULL;
+
+	if (!provider)
+		return false;
+
+	name = vpn_provider_get_driver_name(provider);
+	vpn_driver_data = g_hash_table_lookup(driver_hash, name);
+
+	if (vpn_driver_data && vpn_driver_data->vpn_driver->uses_vpn_agent)
+		return vpn_driver_data->vpn_driver->uses_vpn_agent(provider);
+
+	/*
+	 * Default to using the VPN agent, in cases where the function is not
+	 * implemented. The use of VPN agent must be explicitly dropped.
+	 */
+	return true;
+}
+
 int vpn_register(const char *name, const struct vpn_driver *vpn_driver,
 			const char *program)
 {
@@ -825,6 +846,7 @@ int vpn_register(const char *name, const struct vpn_driver *vpn_driver,
 	data->provider_driver.save = vpn_save;
 	data->provider_driver.set_state = vpn_set_state;
 	data->provider_driver.route_env_parse = vpn_route_env_parse;
+	data->provider_driver.uses_vpn_agent = vpn_uses_vpn_agent;
 
 	if (!driver_hash)
 		driver_hash = g_hash_table_new_full(g_str_hash,
diff --git a/vpn/plugins/vpn.h b/vpn/plugins/vpn.h
index a8d24fc3..b24cbf9b 100644
--- a/vpn/plugins/vpn.h
+++ b/vpn/plugins/vpn.h
@@ -57,6 +57,7 @@ struct vpn_driver {
 	int (*route_env_parse) (struct vpn_provider *provider, const char *key,
 			int *family, unsigned long *idx,
 			enum vpn_provider_route_type *type);
+	bool (*uses_vpn_agent) (struct vpn_provider *provider);
 };
 
 int vpn_register(const char *name, const struct vpn_driver *driver,
diff --git a/vpn/vpn-provider.h b/vpn/vpn-provider.h
index c81476c6..8a8b6bfd 100644
--- a/vpn/vpn-provider.h
+++ b/vpn/vpn-provider.h
@@ -167,6 +167,7 @@ struct vpn_provider_driver {
 	int (*route_env_parse) (struct vpn_provider *provider, const char *key,
 			int *family, unsigned long *idx,
 			enum vpn_provider_route_type *type);
+	bool (*uses_vpn_agent) (struct vpn_provider *provider);
 };
 
 int vpn_provider_driver_register(struct vpn_provider_driver *driver);
-- 
2.39.5