rpc: Implement HTTP-based JSON-RPC server and client

Cargo.lock

@@ -1950,6 +1950,7 @@ dependencies = [
  "futures-rustls",
  "halo2_gadgets",
  "halo2_proofs",
+ "httparse",
  "lazy_static",
  "libc",
  "log",

Cargo.toml

@@ -86,6 +86,7 @@ x509-parser = {version = "0.16.0", features = ["validate", "verify"], optional =
 bs58 = {version = "0.5.1", optional = true}
 serde = {version = "1.0.210", features = ["derive"], optional = true}
 tinyjson = {version = "2.5.1", optional = true}
+httparse = {version = "1.9.5", optional = true}
 semver = {version = "1.0.23", optional = true}
 structopt = {version= "0.3.26", optional = true}
 structopt-toml = {version= "0.5.1", optional = true}
@@ -233,6 +234,7 @@ net = [
 
 rpc = [
     "async-trait",
+    "httparse",
 
     "net",
 ]

src/rpc/client.rs

@@ -24,7 +24,10 @@ use tinyjson::JsonValue;
 use url::Url;
 
 use super::{
-    common::{read_from_stream, write_to_stream, INIT_BUF_SIZE, READ_TIMEOUT},
+    common::{
+        http_read_from_stream_response, http_write_to_stream, read_from_stream, write_to_stream,
+        INIT_BUF_SIZE, READ_TIMEOUT,
+    },
     jsonrpc::*,
 };
 use crate::{
@@ -56,9 +59,18 @@ impl RpcClient {
         let (rep_send, rep_recv) = channel::unbounded();
         let (req_skip_send, req_skip_recv) = channel::unbounded();
 
+        // Figure out if we're using HTTP and rewrite the URL accordingly.
+        let mut dialer_url = endpoint.clone();
+        if endpoint.scheme().starts_with("http+") {
+            let scheme = endpoint.scheme().strip_prefix("http+").unwrap();
+            let url_str = endpoint.as_str().replace(endpoint.scheme(), scheme);
+            dialer_url = url_str.parse()?;
+        }
+        let use_http = endpoint.scheme().starts_with("http+");
+
         // Instantiate Dialer and dial the server
         // TODO: Could add a timeout here
-        let dialer = Dialer::new(endpoint, None).await?;
+        let dialer = Dialer::new(dialer_url, None).await?;
         let stream = dialer.dial(None).await?;
 
         // Create the StoppableTask running the request-reply loop.
@@ -66,7 +78,7 @@ impl RpcClient {
         // using `RpcClient::stop()`.
         let task = StoppableTask::new();
         task.clone().start(
-            Self::reqrep_loop(stream, rep_send, req_recv, req_skip_recv),
+            Self::reqrep_loop(use_http, stream, rep_send, req_recv, req_skip_recv),
             |res| async move {
                 match res {
                     Ok(()) | Err(Error::RpcClientStopped) => {}
@@ -89,6 +101,7 @@ impl RpcClient {
 
     /// Internal function that loops on a given stream and multiplexes the data
     async fn reqrep_loop(
+        use_http: bool,
         stream: Box<dyn PtStream>,
         rep_send: channel::Sender<JsonResult>,
         req_recv: channel::Receiver<(JsonRequest, bool)>,
@@ -111,7 +124,11 @@ impl RpcClient {
                     with_timeout = timeout;
 
                     let request = JsonResult::Request(request);
-                    write_to_stream(&mut writer, &request).await?;
+                    if use_http {
+                        http_write_to_stream(&mut writer, &request).await?;
+                    } else {
+                        write_to_stream(&mut writer, &request).await?;
+                    }
                     Ok::<(), crate::Error>(())
                 },
                 async {
@@ -122,9 +139,23 @@ impl RpcClient {
             .await?;
 
             if with_timeout {
-                let _ = io_timeout(READ_TIMEOUT, read_from_stream(&mut reader, &mut buf)).await?;
+                if use_http {
+                    let _ = io_timeout(
+                        READ_TIMEOUT,
+                        http_read_from_stream_response(&mut reader, &mut buf),
+                    )
+                    .await?;
+                } else {
+                    let _ =
+                        io_timeout(READ_TIMEOUT, read_from_stream(&mut reader, &mut buf)).await?;
+                }
             } else {
-                let _ = read_from_stream(&mut reader, &mut buf).await?;
+                #[allow(clippy::collapsible_else_if)]
+                if use_http {
+                    let _ = http_read_from_stream_response(&mut reader, &mut buf).await?;
+                } else {
+                    let _ = read_from_stream(&mut reader, &mut buf).await?;
+                }
             }
 
             let val: JsonValue = String::from_utf8(buf)?.parse()?;
@@ -280,9 +311,18 @@ impl RpcChadClient {
         let (req_send, req_recv) = channel::unbounded();
         let (rep_send, rep_recv) = channel::unbounded();
 
+        // Figure out if we're using HTTP and rewrite the URL accordingly.
+        let mut dialer_url = endpoint.clone();
+        if endpoint.scheme().starts_with("http+") {
+            let scheme = endpoint.scheme().strip_prefix("http+").unwrap();
+            let url_str = endpoint.as_str().replace(endpoint.scheme(), scheme);
+            dialer_url = url_str.parse()?;
+        }
+        let use_http = endpoint.scheme().starts_with("http+");
+
         // Instantiate Dialer and dial the server
         // TODO: Could add a timeout here
-        let dialer = Dialer::new(endpoint, None).await?;
+        let dialer = Dialer::new(dialer_url, None).await?;
         let stream = dialer.dial(None).await?;
 
         // Create the StoppableTask running the request-reply loop.
@@ -290,7 +330,7 @@ impl RpcChadClient {
         // using `RpcChadClient::stop()`.
         let task = StoppableTask::new();
         task.clone().start(
-            Self::reqrep_loop(stream, rep_send, req_recv),
+            Self::reqrep_loop(use_http, stream, rep_send, req_recv),
             |res| async move {
                 match res {
                     Ok(()) | Err(Error::RpcClientStopped) => {}
@@ -313,6 +353,7 @@ impl RpcChadClient {
 
     /// Internal function that loops on a given stream and multiplexes the data
     async fn reqrep_loop(
+        use_http: bool,
         stream: Box<dyn PtStream>,
         rep_send: channel::Sender<JsonResult>,
         req_recv: channel::Receiver<JsonRequest>,
@@ -330,11 +371,19 @@ impl RpcChadClient {
                 async {
                     let request = req_recv.recv().await?;
                     let request = JsonResult::Request(request);
-                    write_to_stream(&mut writer, &request).await?;
+                    if use_http {
+                        http_write_to_stream(&mut writer, &request).await?;
+                    } else {
+                        write_to_stream(&mut writer, &request).await?;
+                    }
                     Ok::<(), crate::Error>(())
                 },
                 async {
-                    let _ = read_from_stream(&mut reader, &mut buf).await?;
+                    if use_http {
+                        let _ = http_read_from_stream_response(&mut reader, &mut buf).await?;
+                    } else {
+                        let _ = read_from_stream(&mut reader, &mut buf).await?;
+                    }
                     let val: JsonValue = String::from_utf8(buf)?.parse()?;
                     let rep = JsonResult::try_from_value(&val)?;
                     rep_send.send(rep).await?;

src/rpc/common.rs

@@ -18,15 +18,156 @@
 
 use std::{io, time::Duration};
 
+use log::error;
 use smol::io::{AsyncReadExt, AsyncWriteExt, BufReader, ReadHalf, WriteHalf};
 
 use super::jsonrpc::*;
 use crate::net::transport::PtStream;
 
 pub(super) const INIT_BUF_SIZE: usize = 4096; // 4K
-pub(super) const MAX_BUF_SIZE: usize = 1024 * 8192; // 8M
+pub(super) const MAX_BUF_SIZE: usize = 1024 * 1024 * 16; // 16M
 pub(super) const READ_TIMEOUT: Duration = Duration::from_secs(30);
 
+/// Internal read function that reads from the active stream into a buffer.
+/// Performs HTTP POST request parsing. Returns the request body length.
+pub(super) async fn http_read_from_stream_request(
+    reader: &mut BufReader<ReadHalf<Box<dyn PtStream>>>,
+    buf: &mut Vec<u8>,
+) -> io::Result<usize> {
+    let mut total_read = 0;
+
+    // Intermediate buffer we use to read byte-by-byte.
+    let mut tmpbuf = [0_u8];
+
+    while total_read < MAX_BUF_SIZE {
+        buf.resize(total_read + INIT_BUF_SIZE, 0u8);
+
+        match reader.read(&mut tmpbuf).await {
+            Ok(0) if total_read == 0 => return Err(io::ErrorKind::ConnectionAborted.into()),
+            Ok(0) => break, // Finished reading
+            Ok(_) => {
+                // Copy the read byte to the destination buffer.
+                buf[total_read] = tmpbuf[0];
+                total_read += 1;
+
+                // In HTTP, when we reach '\r\n\r\n' we know we've read the headers.
+                // The rest is the body. Headers should contain Content-Length which
+                // tells us the remaining amount of bytes to read.
+                if total_read > 4 && buf[total_read - 4..total_read] == [b'\r', b'\n', b'\r', b'\n']
+                {
+                    break
+                }
+            }
+
+            Err(e) => return Err(e),
+        }
+    }
+
+    // Here we parse the HTTP for correctness and find Content-Length
+    let mut headers = [httparse::EMPTY_HEADER; 8];
+    let mut req = httparse::Request::new(&mut headers);
+    let _body_offset = match req.parse(buf) {
+        Ok(v) => v.unwrap(), // TODO: This should check httparse::Status::is_partial()
+        Err(e) => {
+            error!("[RPC] Failed parsing HTTP request: {}", e);
+            return Err(io::ErrorKind::InvalidData.into())
+        }
+    };
+
+    let mut content_length: usize = 0;
+    for header in headers {
+        if header.name.to_lowercase() == "content-length" {
+            let s = String::from_utf8_lossy(header.value);
+            content_length = match s.parse() {
+                Ok(v) => v,
+                Err(_) => return Err(io::ErrorKind::InvalidData.into()),
+            };
+        }
+    }
+
+    if content_length == 0 || content_length > MAX_BUF_SIZE {
+        return Err(io::ErrorKind::InvalidData.into())
+    }
+
+    // Now we know the request body size. Read it into the buffer.
+    buf.clear();
+    buf.resize(content_length, 0_u8);
+    reader.read(buf).await?;
+
+    assert!(buf.len() == content_length);
+    Ok(content_length)
+}
+
+/// Internal read function that reads from the active stream into a buffer.
+/// Performs HTTP POST response parsing. Returns the response body length.
+pub(super) async fn http_read_from_stream_response(
+    reader: &mut BufReader<ReadHalf<Box<dyn PtStream>>>,
+    buf: &mut Vec<u8>,
+) -> io::Result<usize> {
+    let mut total_read = 0;
+
+    // Intermediate buffer we use to read byte-by-byte.
+    let mut tmpbuf = [0_u8];
+
+    while total_read < MAX_BUF_SIZE {
+        buf.resize(total_read + INIT_BUF_SIZE, 0u8);
+
+        match reader.read(&mut tmpbuf).await {
+            Ok(0) if total_read == 0 => return Err(io::ErrorKind::ConnectionAborted.into()),
+            Ok(0) => break, // Finished reading
+            Ok(_) => {
+                // Copy the read byte to the destination buffer.
+                buf[total_read] = tmpbuf[0];
+                total_read += 1;
+
+                // In HTTP, when we reach '\r\n\r\n' we know we've read the headers.
+                // The rest is the body. Headers should contain Content-Length which
+                // tells us the remaining amount of bytes to read.
+                if total_read > 4 && buf[total_read - 4..total_read] == [b'\r', b'\n', b'\r', b'\n']
+                {
+                    break
+                }
+            }
+
+            Err(e) => return Err(e),
+        }
+    }
+
+    // Here we parse the HTTP for correctness and find Content-Length
+    let mut headers = [httparse::EMPTY_HEADER; 8];
+    let mut resp = httparse::Response::new(&mut headers);
+    let _body_offset = match resp.parse(buf) {
+        Ok(v) => v.unwrap(), // TODO: This should check httparse::Status::is_partial()
+        Err(e) => {
+            error!("[RPC] Failed parsing HTTP response: {}", e);
+            return Err(io::ErrorKind::InvalidData.into())
+        }
+    };
+
+    let mut content_length: usize = 0;
+    for header in headers {
+        if header.name.to_lowercase() == "content-length" {
+            let s = String::from_utf8_lossy(header.value);
+            content_length = match s.parse() {
+                Ok(v) => v,
+                Err(_) => return Err(io::ErrorKind::InvalidData.into()),
+            };
+        }
+    }
+
+    if content_length == 0 || content_length > MAX_BUF_SIZE {
+        return Err(io::ErrorKind::InvalidData.into())
+    }
+
+    // Now we know the response body size. Read it into the buffer.
+    buf.clear();
+    buf.resize(content_length, 0_u8);
+    reader.read(buf).await?;
+
+    assert!(buf.len() == content_length);
+    Ok(content_length)
+}
+
 /// Internal read function that reads from the active stream into a buffer.
 /// Reading stops upon reaching CRLF or LF, or when `MAX_BUF_SIZE` is reached.
 pub(super) async fn read_from_stream(
@@ -39,7 +180,7 @@ pub(super) async fn read_from_stream(
     let mut tmpbuf = [0_u8];
 
     while total_read < MAX_BUF_SIZE {
-        buf.resize(total_read + INIT_BUF_SIZE, 0);
+        buf.resize(total_read + INIT_BUF_SIZE, 0u8);
 
         match reader.read(&mut tmpbuf).await {
             Ok(0) if total_read == 0 => return Err(io::ErrorKind::ConnectionAborted.into()),
@@ -68,6 +209,29 @@ pub(super) async fn read_from_stream(
     Ok(total_read)
 }
 
+/// Internal write function that writes a JSON-RPC object to the active stream.
+/// Sent as an HTTP response.
+pub(super) async fn http_write_to_stream(
+    writer: &mut WriteHalf<Box<dyn PtStream>>,
+    object: &JsonResult,
+) -> io::Result<()> {
+    let (status_line, object_str) = match object {
+        JsonResult::Notification(v) => ("HTTP/1.1 200 OK", v.stringify().unwrap()),
+        JsonResult::Response(v) => ("HTTP/1.1 200 OK", v.stringify().unwrap()),
+        JsonResult::Error(v) => ("HTTP/1.1 400 Bad Request", v.stringify().unwrap()),
+        JsonResult::Request(v) => ("POST /json_rpc HTTP/1.1", v.stringify().unwrap()),
+        _ => unreachable!(),
+    };
+
+    let length = object_str.len();
+    let data = format!("{status_line}\r\nContent-Length: {length}\r\nContent-Type: application/json\r\n\r\n{object_str}");
+
+    writer.write_all(data.as_bytes()).await?;
+    writer.flush().await?;
+
+    Ok(())
+}
+
 /// Internal write function that writes a JSON-RPC object to the active stream.
 pub(super) async fn write_to_stream(
     writer: &mut WriteHalf<Box<dyn PtStream>>,

src/rpc/server.rs

@@ -28,7 +28,10 @@ use tinyjson::JsonValue;
 use url::Url;
 
 use super::{
-    common::{read_from_stream, write_to_stream, INIT_BUF_SIZE},
+    common::{
+        http_read_from_stream_request, http_write_to_stream, read_from_stream, write_to_stream,
+        INIT_BUF_SIZE,
+    },
     jsonrpc::*,
 };
 use crate::{
@@ -80,6 +83,7 @@ async fn handle_request(
     rh: Arc<impl RequestHandler + 'static>,
     ex: Arc<smol::Executor<'_>>,
     tasks: Arc<Mutex<HashSet<Arc<StoppableTask>>>>,
+    use_http: bool,
     req: JsonRequest,
 ) -> Result<()> {
     let rep = rh.handle_request(req).await;
@@ -107,10 +111,20 @@ async fn handle_request(
                         let notification = JsonResult::Notification(notification);
 
                         let mut writer_lock = writer_.lock().await;
-                        if let Err(e) = write_to_stream(&mut writer_lock, &notification).await {
-                            subscription.unsubscribe().await;
-                            return Err(e.into())
+
+                        #[allow(clippy::collapsible_else_if)]
+                        if use_http {
+                            if let Err(e) = http_write_to_stream(&mut writer_lock, &notification).await {
+                                subscription.unsubscribe().await;
+                                return Err(e.into())
+                            }
+                        } else {
+                            if let Err(e) = write_to_stream(&mut writer_lock, &notification).await {
+                                subscription.unsubscribe().await;
+                                return Err(e.into())
+                            }
                         }
+
                         drop(writer_lock);
                     }
                 },
@@ -133,7 +147,11 @@ async fn handle_request(
             // Write the response
             debug!(target: "rpc::server", "{} <-- {}", addr, reply.stringify()?);
             let mut writer_lock = writer.lock().await;
-            write_to_stream(&mut writer_lock, &reply.into()).await?;
+            if use_http {
+                http_write_to_stream(&mut writer_lock, &reply.into()).await?;
+            } else {
+                write_to_stream(&mut writer_lock, &reply.into()).await?;
+            }
             drop(writer_lock);
 
             let task = StoppableTask::new();
@@ -157,10 +175,19 @@ async fn handle_request(
                         let notification = JsonResult::Notification(notification);
 
                         let mut writer_lock = writer_.lock().await;
-                        if let Err(e) = write_to_stream(&mut writer_lock, &notification).await {
-                            subscription.unsubscribe().await;
-                            drop(writer_lock);
-                            return Err(e.into())
+                        #[allow(clippy::collapsible_else_if)]
+                        if use_http {
+                            if let Err(e) = http_write_to_stream(&mut writer_lock, &notification).await {
+                                subscription.unsubscribe().await;
+                                drop(writer_lock);
+                                return Err(e.into())
+                            }
+                        } else {
+                            if let Err(e) = write_to_stream(&mut writer_lock, &notification).await {
+                                subscription.unsubscribe().await;
+                                drop(writer_lock);
+                                return Err(e.into())
+                            }
                         }
                         drop(writer_lock);
                     }
@@ -187,14 +214,22 @@ async fn handle_request(
         JsonResult::Response(ref v) => {
             debug!(target: "rpc::server", "{} <-- {}", addr, v.stringify()?);
             let mut writer_lock = writer.lock().await;
-            write_to_stream(&mut writer_lock, &rep).await?;
+            if use_http {
+                http_write_to_stream(&mut writer_lock, &rep).await?;
+            } else {
+                write_to_stream(&mut writer_lock, &rep).await?;
+            }
             drop(writer_lock);
         }
 
         JsonResult::Error(ref v) => {
             debug!(target: "rpc::server", "{} <-- {}", addr, v.stringify()?);
             let mut writer_lock = writer.lock().await;
-            write_to_stream(&mut writer_lock, &rep).await?;
+            if use_http {
+                http_write_to_stream(&mut writer_lock, &rep).await?;
+            } else {
+                write_to_stream(&mut writer_lock, &rep).await?;
+            }
             drop(writer_lock);
         }
     }
@@ -211,6 +246,7 @@ pub async fn accept(
     addr: Url,
     rh: Arc<impl RequestHandler + 'static>,
     conn_limit: Option<usize>,
+    use_http: bool,
     ex: Arc<smol::Executor<'_>>,
 ) -> Result<()> {
     // If there's a connection limit set, we will refuse connections
@@ -232,7 +268,11 @@ pub async fn accept(
         let mut buf = Vec::with_capacity(INIT_BUF_SIZE);
 
         let mut reader_lock = reader.lock().await;
-        let _ = read_from_stream(&mut reader_lock, &mut buf).await?;
+        if use_http {
+            let _ = http_read_from_stream_request(&mut reader_lock, &mut buf).await?;
+        } else {
+            let _ = read_from_stream(&mut reader_lock, &mut buf).await?;
+        }
         drop(reader_lock);
 
         let line = match String::from_utf8(buf) {
@@ -287,6 +327,7 @@ pub async fn accept(
                 rh.clone(),
                 ex.clone(),
                 tasks.clone(),
+                use_http,
                 req,
             ),
             move |_| async move {
@@ -311,6 +352,7 @@ async fn run_accept_loop(
     listener: Box<dyn PtListener>,
     rh: Arc<impl RequestHandler + 'static>,
     conn_limit: Option<usize>,
+    use_http: bool,
     ex: Arc<smol::Executor<'_>>,
 ) -> Result<()> {
     loop {
@@ -327,7 +369,7 @@ async fn run_accept_loop(
                 let task_ = task.clone();
                 let ex_ = ex.clone();
                 task.clone().start(
-                    accept(reader, writer, url.clone(), rh.clone(), conn_limit, ex_),
+                    accept(reader, writer, url.clone(), rh.clone(), conn_limit, use_http, ex_),
                     |_| async move {
                         info!(target: "rpc::server", "[RPC] Closed conn from {}", url);
                         rh_.clone().unmark_connection(task_.clone()).await;
@@ -374,16 +416,29 @@ async fn run_accept_loop(
     }
 }
 
-/// Start a JSON-RPC server bound to the given accept URL and use the
+/// Start a JSON-RPC server bound to the givven accept URL and use the
 /// given [`RequestHandler`] to handle incoming requests.
+///
+/// The supported network schemes can be prefixed with `http+` to serve
+/// JSON-RPC over HTTP/1.1.
 pub async fn listen_and_serve(
     accept_url: Url,
     rh: Arc<impl RequestHandler + 'static>,
     conn_limit: Option<usize>,
     ex: Arc<smol::Executor<'_>>,
 ) -> Result<()> {
-    let listener = Listener::new(accept_url, None).await?.listen().await?;
-    run_accept_loop(listener, rh, conn_limit, ex.clone()).await
+    // Figure out if we're using HTTP and rewrite the URL accordingly.
+    let mut listen_url = accept_url.clone();
+    if accept_url.scheme().starts_with("http+") {
+        let scheme = accept_url.scheme().strip_prefix("http+").unwrap();
+        let url_str = accept_url.as_str().replace(accept_url.scheme(), scheme);
+        listen_url = url_str.parse()?;
+    }
+
+    let listener = Listener::new(listen_url, None).await?.listen().await?;
+
+    let use_http = accept_url.scheme().starts_with("http+");
+    run_accept_loop(listener, rh, conn_limit, use_http, ex.clone()).await
 }
 
 #[cfg(test)]

tests/jsonrpc.rs

@@ -71,8 +71,29 @@ impl RequestHandler for RpcSrv {
     }
 }
 
+/// Initialize the logging mechanism
+fn init_logger() {
+    let mut cfg = simplelog::ConfigBuilder::new();
+
+    // We check this error so we can execute same file tests in parallel,
+    // otherwise second one fails to init logger here.
+    if simplelog::TermLogger::init(
+        //simplelog::LevelFilter::Info,
+        simplelog::LevelFilter::Debug,
+        //simplelog::LevelFilter::Trace,
+        cfg.build(),
+        simplelog::TerminalMode::Mixed,
+        simplelog::ColorChoice::Auto,
+    )
+    .is_err()
+    {
+        log::debug!("Logger initialized");
+    }
+}
+
 #[test]
 fn jsonrpc_reqrep() -> Result<()> {
+    init_logger();
     let executor = Arc::new(Executor::new());
 
     smol::block_on(executor.run(async {
@@ -119,3 +140,53 @@ fn jsonrpc_reqrep() -> Result<()> {
         Ok(())
     }))
 }
+
+#[test]
+fn http_jsonrpc_reqrep() -> Result<()> {
+    init_logger();
+    let executor = Arc::new(Executor::new());
+
+    smol::block_on(executor.run(async {
+        // Find an available port
+        let listener = TcpListener::bind("127.0.0.1:0").await?;
+        let sockaddr = listener.local_addr()?;
+        let endpoint = Url::parse(&format!("http+tcp://127.0.0.1:{}", sockaddr.port()))?;
+        drop(listener);
+
+        let rpcsrv = Arc::new(RpcSrv {
+            stop_sub: smol::channel::unbounded(),
+            rpc_connections: Mutex::new(HashSet::new()),
+        });
+        let rpcsrv_ = Arc::clone(&rpcsrv);
+
+        let rpc_task = StoppableTask::new();
+        rpc_task.clone().start(
+            listen_and_serve(endpoint.clone(), rpcsrv.clone(), None, executor.clone()),
+            |res| async move {
+                match res {
+                    Ok(()) | Err(Error::RpcServerStopped) => rpcsrv_.stop_connections().await,
+                    Err(e) => eprintln!("Failed starting JSON-RPC server: {}", e),
+                }
+            },
+            Error::RpcServerStopped,
+            executor.clone(),
+        );
+
+        msleep(500).await;
+
+        let client = RpcClient::new(endpoint, executor.clone()).await?;
+        let req = JsonRequest::new("ping", vec![].into());
+        let rep = client.request(req).await?;
+
+        let rep = String::try_from(rep).unwrap();
+        assert_eq!(&rep, "pong");
+
+        let req = JsonRequest::new("kill", vec![].into());
+        let rep = client.request(req).await?;
+
+        let rep = String::try_from(rep).unwrap();
+        assert_eq!(&rep, "bye");
+
+        Ok(())
+    }))
+}