add: implement ttl

src/setting.h

@@ -2,6 +2,7 @@
 
 #include "host.h"
 
+#include <stdint.h>
 #include <stddef.h>
 #include <stdbool.h>
 
@@ -12,7 +13,7 @@ struct setting
     bool flood;
     bool numeric_only;
     size_t timeout;
-    size_t ttl;
+    uint8_t ttl;
     size_t payload_size;
     struct hostenv dest;
 };