Rename Response::Ok to Response::Nil.

This is a better name because it signals "no data in response" rather
than "Ok", which is semantically mixed with `Ok/Err` of `Result`.

zebra-network/src/peer/connection.rs

@@ -53,11 +53,11 @@ impl Handler {
         use Handler::*;
         let mut ignored_msg = None;
         // XXX can this be avoided?
-        let tmp_state = std::mem::replace(self, Finished(Ok(Response::Ok)));
+        let tmp_state = std::mem::replace(self, Finished(Ok(Response::Nil)));
         *self = match (tmp_state, msg) {
             (Ping(req_nonce), Message::Pong(rsp_nonce)) => {
                 if req_nonce == rsp_nonce {
-                    Finished(Ok(Response::Ok))
+                    Finished(Ok(Response::Nil))
                 } else {
                     Ping(req_nonce)
                 }
@@ -407,7 +407,7 @@ where
         };
 
         match rsp {
-            Response::Ok => { /* generic success, do nothing */ }
+            Response::Nil => { /* generic success, do nothing */ }
             Response::Error => {
                 if let Err(e) = self.peer_tx.send(Message::from(PeerError::Rejected)).await {
                     self.fail_with(e.into());

zebra-network/src/protocol/internal/response.rs

@@ -8,8 +8,8 @@ use crate::meta_addr::MetaAddr;
 /// A response to a network request, represented in internal format.
 #[derive(Clone, Debug)]
 pub enum Response {
-    /// Generic success.
+    /// A response with no data.
-    Ok,
+    Nil,
 
     /// Generic error.
     Error,

zebrad/src/commands/connect.rs

@@ -51,7 +51,7 @@ impl ConnectCmd {
         let node = Buffer::new(
             service_fn(|req| async move {
                 info!(?req);
-                Ok::<Response, Error>(Response::Ok)
+                Ok::<Response, Error>(Response::Nil)
             }),
             1,
         );

zebrad/src/commands/seed.rs

@@ -92,7 +92,7 @@ impl Service<Request> for SeedService {
             }
             _ => {
                 debug!("ignoring request");
-                Ok(Response::Ok)
+                Ok(Response::Nil)
             }
         };
         Box::pin(futures::future::ready(response))