setup route expiration in kernel if supported

kernel >= 4.5 (with commit https://github.com/torvalds/linux/commit/32bc201e1974976b7d3fea9a9b17bb7392ca6394) supports
RTA_EXPIRES netlink attribute to set router lifetime. This simply detect
the kernel version (>=4.5) and set the lifetime properly, fallback to
expiring route in userspace for kernel that doesnt support it.

Signed-off-by: Daniel Dao <dqminh89@gmail.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/src/network/networkd-util.c b/src/network/networkd-util.c
index b9c533fcc7..7ea14155b6 100644
--- a/src/network/networkd-util.c
+++ b/src/network/networkd-util.c
@@ -18,6 +18,7 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#include "condition.h"
 #include "conf-parser.h"
 #include "networkd-util.h"
 #include "parse-util.h"
@@ -99,3 +100,23 @@ int config_parse_address_family_boolean_with_kernel(
 
         return 0;
 }
+
+/* Router lifetime can be set with netlink interface since kernel >= 4.5
+ * so for the supported kernel we dont need to expire routes in userspace */
+int kernel_route_expiration_supported(void) {
+        static int cached = -1;
+        int r;
+
+        if (cached < 0) {
+                Condition c = {
+                        .type = CONDITION_KERNEL_VERSION,
+                        .parameter = (char *) ">= 4.5"
+                };
+                r = condition_test(&c);
+                if (r < 0)
+                        return r;
+
+                cached = r;
+        }
+        return cached;
+}