assert public ip is ipv4

transaction-relayer/src/main.rs

@@ -261,6 +261,13 @@ fn main() {
         response.parse().unwrap()
     };
     info!("public ip: {:?}", public_ip);
+    assert!(
+        public_ip.is_ipv4(),
+        "Your public IP address needs to be IPV4 but is currently listed as {}. \
+    If you are seeing this error and not passing in --public-ip, \
+    please find your public ip address and pass it in on the command line",
+        public_ip
+    );
 
     // Supporting IPV6 addresses is a DOS vector since they are cheap and there's a much larger amount of them.
     // The DOS is specifically with regards to the challenges queue filling up and starving other legitimate