From ee258ac1154f20cd98a2ff6816ea78d5c308774e Mon Sep 17 00:00:00 2001
From: ryan <ryan@distrust.co>
Date: Sun, 5 Nov 2023 23:15:48 -0600
Subject: [PATCH] keyforkd: allow sending server-side error to clients

---
 keyforkd-client/src/lib.rs | 16 ++++++++++++++--
 keyforkd/src/middleware.rs | 17 ++++++++++-------
 2 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/keyforkd-client/src/lib.rs b/keyforkd-client/src/lib.rs
index 3ac56a1..4fad02d 100644
--- a/keyforkd-client/src/lib.rs
+++ b/keyforkd-client/src/lib.rs
@@ -1,7 +1,7 @@
 use std::{collections::HashMap, os::unix::net::UnixStream, path::PathBuf};
 
 use keyfork_frame::{try_decode_from, try_encode_to, DecodeError, EncodeError};
-use keyforkd_models::{Request, Response /* Error as KeyforkdError */};
+use keyforkd_models::{Request, Response, Error as KeyforkdError};
 
 #[cfg(test)]
 mod tests;
@@ -25,6 +25,9 @@ pub enum Error {
 
     #[error("Could not perform frame transformation: {0}")]
     FrameDec(#[from] DecodeError),
+
+    #[error("Error in Keyforkd: {0}")]
+    Keyforkd(#[from] KeyforkdError)
 }
 
 pub type Result<T, E = Error> = std::result::Result<T, E>;
@@ -51,23 +54,32 @@ pub fn get_socket() -> Result<UnixStream, Error> {
     UnixStream::connect(&socket_path).map_err(|e| Error::Connect(e, socket_path))
 }
 
+/// A client to interact with Keyforkd.
+///
+/// Upon creation, a socket is opened, and is kept open for the duration of the object's lifetime.
+/// Currently, Keyforkd does not support the reuse of sockets. Attempting to reuse the socket after
+/// previously using it will likely result in an error.
 #[derive(Debug)]
 pub struct Client {
     socket: UnixStream,
 }
 
 impl Client {
+    /// Create a new client from a given already-connected [`UnixStream`].
     pub fn new(socket: UnixStream) -> Self {
         Self { socket }
     }
 
+    /// Create a new client using well-known socket locations.
     pub fn discover_socket() -> Result<Self> {
         get_socket().map(|socket| Self { socket })
     }
 
+    /// Serialize and send a [`Request`] to the server, awaiting a [`Result<Response>`].
     pub fn request(&mut self, req: &Request) -> Result<Response> {
         try_encode_to(&bincode::serialize(&req)?, &mut self.socket)?;
         let resp = try_decode_from(&mut self.socket)?;
-        bincode::deserialize(&resp).map_err(From::from)
+        let resp: Result<Response, KeyforkdError> = bincode::deserialize(&resp)?;
+        resp.map_err(From::from)
     }
 }
diff --git a/keyforkd/src/middleware.rs b/keyforkd/src/middleware.rs
index 2822239..a8d6cbc 100644
--- a/keyforkd/src/middleware.rs
+++ b/keyforkd/src/middleware.rs
@@ -59,7 +59,7 @@ where
     S: Service<Request>,
     Request: DeserializeOwned,
     <S as Service<Request>>::Response: Serialize,
-    <S as Service<Request>>::Error: std::error::Error,
+    <S as Service<Request>>::Error: std::error::Error + Serialize,
     <S as Service<Request>>::Future: Send + 'static,
 {
     type Response = Vec<u8>;
@@ -86,9 +86,11 @@ where
         let response = self.service.call(request);
 
         Box::pin(async move {
-            let response = response
-                .await
-                .map_err(|e| BincodeServiceError::Call(e.to_string()))?;
+            let response = response.await;
+            #[cfg(feature = "tracing")]
+            if let Err(e) = &response {
+                tracing::error!("Error performing derivation: {e}");
+            }
             serialize(&response).map_err(|e| BincodeServiceError::Convert(e.to_string()))
         })
     }
@@ -116,7 +118,7 @@ mod tests {
 
     struct App;
 
-    #[derive(Debug, thiserror::Error)]
+    #[derive(Debug, thiserror::Error, Serialize)]
     enum Infallible {}
 
     impl Service<Test> for App {
@@ -141,7 +143,8 @@ mod tests {
 
     #[tokio::test]
     async fn can_serde_responses() {
-        let content = serialize(&Test::new()).unwrap();
+        let test = Test::new();
+        let content = serialize(&test).unwrap();
         let mut service = ServiceBuilder::new()
             .layer(BincodeLayer::<Test>::default())
             .service(App);
@@ -152,6 +155,6 @@ mod tests {
             .call(content.clone())
             .await
             .unwrap();
-        assert_eq!(result, content);
+        assert_eq!(result, serialize(&Result::<Test, Infallible>::Ok(test)).unwrap());
     }
 }