Add NANO_TO_SEC constant.

src/xdpfw.h

@@ -6,6 +6,7 @@
 #define MAX_FILTERS 80
 #define MAX_TRACK_IPS 100000
 #define MAX_CPUS 256
+#define NANO_TO_SEC 1000000000
 
 #ifdef __BPF__
 #define likely(x) __builtin_expect(!!(x), 1)

src/xdpfw_kern.c

@@ -202,7 +202,7 @@ int xdp_prog_main(struct xdp_md *ctx)
     if (ip_stats)
     {
         // Check for reset.
-        if ((now - ip_stats->tracking) > 1000000000)
+        if ((now - ip_stats->tracking) > NANO_TO_SEC)
         {
             ip_stats->pps = 0;
             ip_stats->bps = 0;