core: give better error reason why device is incompatible with profile

Note the special error codes  NM_UTILS_ERROR_CONNECTION_AVAILABLE_*.
This will be used to determine, whether the profile is fundamentally
incompatible with the device, or whether just some other properties
mismatch. That information will be importand during a plain `nmcli
connection up`, where NetworkManager searches all devices for a device
to activate. If no device is found (and multiple errors happened),
we want to show the error that is most likely relevant for the user.

Also note, how NMDevice's check_connection_compatible() uses the new
class field "device_class->connection_type_check_compatible" to simplify
checks for compatible profiles.

The error reason is still unused.

2 files changed, 38 insertions, 0 deletions

diff --git a/libnm-core/nm-connection.c b/libnm-core/nm-connection.c
index 2f8cb4e90..29fdd9790 100644
--- a/libnm-core/nm-connection.c
+++ b/libnm-core/nm-connection.c
@@ -225,6 +225,40 @@ nm_connection_get_setting_by_name (NMConnection *connection, const char *name)
 	return type ? _connection_get_setting (connection, type) : NULL;
 }
 
+/*****************************************************************************/
+
+gpointer /* (NMSetting *) */
+_nm_connection_check_main_setting (NMConnection *connection,
+                                   const char *setting_name,
+                                   GError **error)
+{
+	NMSetting *setting;
+
+	nm_assert (NM_IS_CONNECTION (connection));
+	nm_assert (setting_name);
+
+	if (!nm_connection_is_type (connection, setting_name)) {
+		nm_utils_error_set (error,
+		                    NM_UTILS_ERROR_CONNECTION_AVAILABLE_INCOMPATIBLE,
+		                    "connection type is not \"%s\"",
+		                    setting_name);
+		return NULL;
+	}
+
+	setting = nm_connection_get_setting_by_name (connection, setting_name);
+	if (!setting) {
+		nm_utils_error_set (error,
+		                    NM_UTILS_ERROR_CONNECTION_AVAILABLE_INCOMPATIBLE,
+		                    "connection misses \"%s\" settings",
+		                    setting_name);
+		return NULL;
+	}
+
+	return setting;
+}
+
+/*****************************************************************************/
+
 static gboolean
 validate_permissions_type (GVariant *variant, GError **error)
 {
diff --git a/libnm-core/nm-core-internal.h b/libnm-core/nm-core-internal.h
index 3808a9e61..4945118ff 100644
--- a/libnm-core/nm-core-internal.h
+++ b/libnm-core/nm-core-internal.h
@@ -140,6 +140,10 @@ gboolean _nm_connection_replace_settings (NMConnection *connection,
                                           NMSettingParseFlags parse_flags,
                                           GError **error);
 
+gpointer _nm_connection_check_main_setting (NMConnection *connection,
+                                            const char *setting_name,
+                                            GError **error);
+
 /**
  * NMSettingVerifyResult:
  * @NM_SETTING_VERIFY_SUCCESS: the setting verifies successfully