feat: add resp3 support

docker/config/integration.toml

@@ -8,6 +8,7 @@ servers = [
 ]
 password = "front-standalone-secret"
 backend_password = "backend-standalone-secret"
+backend_resp_version = "resp3"
 
 [[clusters]]
 name = "cluster"
@@ -24,3 +25,4 @@ auth = { password = "front-cluster-secret", users = [
     { username = "ops", password = "ops-secret" }
 ] }
 backend_password = "backend-cluster-secret"
+backend_resp_version = "resp3"

docker/integration-test.sh

@@ -41,6 +41,26 @@ wait_for_cluster() {
 
 wait_for_cluster
 
+if ! hello_standalone="$(REDISCLI_AUTH="$STANDALONE_PASS" redis-cli -h aster-proxy -p 6380 --raw HELLO 3 AUTH default "$STANDALONE_PASS")"; then
+  echo "HELLO 3 handshake against standalone proxy failed" >&2
+  exit 1
+fi
+if ! printf "%s\n" "$hello_standalone" | awk 'BEGIN{found=0} {if(prev=="proto" && $0=="3"){found=1} prev=$0} END{exit(found?0:1)}'; then
+  echo "HELLO 3 response from standalone proxy missing proto=3:" >&2
+  printf "%s\n" "$hello_standalone" >&2
+  exit 1
+fi
+
+if ! hello_cluster="$(REDISCLI_AUTH="$CLUSTER_USER_PASS" redis-cli -h aster-proxy -p 6381 --user "$CLUSTER_USER" --raw HELLO 3 AUTH "$CLUSTER_USER" "$CLUSTER_USER_PASS")"; then
+  echo "HELLO 3 handshake against cluster proxy failed" >&2
+  exit 1
+fi
+if ! printf "%s\n" "$hello_cluster" | awk 'BEGIN{found=0} {if(prev=="proto" && $0=="3"){found=1} prev=$0} END{exit(found?0:1)}'; then
+  echo "HELLO 3 response from cluster proxy missing proto=3:" >&2
+  printf "%s\n" "$hello_cluster" >&2
+  exit 1
+fi
+
 noauth_output="$(redis-cli -h aster-proxy -p 6380 PING 2>&1 || true)"
 if echo "$noauth_output" | grep -q "PONG"; then
   echo "Expected standalone proxy to require authentication" >&2

src/auth/mod.rs

@@ -100,6 +100,17 @@ impl BackendAuth {
             .expect("AUTH command is always valid")
     }
 
+    pub fn hello_credentials(&self) -> Option<(Bytes, Bytes)> {
+        match self.parts.len() {
+            2 => Some((
+                Bytes::from_static(DEFAULT_USER.as_bytes()),
+                self.parts[1].clone(),
+            )),
+            3 => Some((self.parts[1].clone(), self.parts[2].clone())),
+            _ => None,
+        }
+    }
+
     pub async fn apply_to_stream(
         &self,
         framed: &mut Framed<TcpStream, RespCodec>,

src/cluster/mod.rs

@@ -25,8 +25,8 @@ use crate::hotkey::Hotkey;
 use crate::info::{InfoContext, ProxyMode};
 use crate::metrics;
 use crate::protocol::redis::{
-    BlockingKind, MultiDispatch, RedisCommand, RespCodec, RespValue, SlotMap, SubCommand,
-    SubResponse, SubscriptionKind, SLOT_COUNT,
+    BlockingKind, MultiDispatch, RedisCommand, RespCodec, RespValue, RespVersion, SlotMap,
+    SubCommand, SubResponse, SubscriptionKind, SLOT_COUNT,
 };
 use crate::slowlog::Slowlog;
 use crate::utils::{crc16, trim_hash_tag};
@@ -78,6 +78,7 @@ impl ClusterProxy {
             runtime.clone(),
             REQUEST_TIMEOUT_MS,
             backend_auth.clone(),
+            config.backend_resp_version,
         ));
         let pool = Arc::new(ConnectionPool::new(cluster.clone(), connector.clone()));
         let auth = config
@@ -143,17 +144,25 @@ impl ClusterProxy {
         let client_id = ClientId::new();
         let _guard = FrontConnectionGuard::new(&self.cluster);
 
-        let (mut sink, stream) = Framed::new(socket, RespCodec::default()).split();
+        let framed = Framed::new(socket, RespCodec::default());
+        let codec_handle = framed.codec().clone();
+        let (mut sink, stream) = framed.split();
         let mut stream = stream.fuse();
-        let mut pending: FuturesOrdered<BoxFuture<'static, RespValue>> = FuturesOrdered::new();
+        let mut pending: FuturesOrdered<BoxFuture<'static, (RespValue, Option<RespVersion>)>> =
+            FuturesOrdered::new();
+        let mut _resp3_negotiated = codec_handle.version() == RespVersion::Resp3;
         let mut inflight = 0usize;
         let mut stream_closed = false;
         let mut auth_state = self.auth.as_ref().map(|auth| auth.new_session());
 
         loop {
             tokio::select! {
-                Some(resp) = pending.next(), if inflight > 0 => {
+                Some((resp, version)) = pending.next(), if inflight > 0 => {
                     inflight -= 1;
+                    if let Some(version) = version {
+                        codec_handle.set_version(version);
+                        _resp3_negotiated = version == RespVersion::Resp3;
+                    }
                     sink.send(resp).await?;
                 }
                 frame_opt = stream.next(), if !stream_closed && inflight < PIPELINE_LIMIT => {
@@ -168,14 +177,13 @@ impl ClusterProxy {
                                                 cmd = new_cmd;
                                             }
                                             AuthAction::Reply(resp) => {
-                                                let fut = async move { resp };
+                                                let fut = async move { (resp, None) };
                                                 pending.push_back(Box::pin(fut));
                                                 inflight += 1;
                                                 continue;
                                             }
                                         }
                                     }
-
                                     if matches!(cmd.as_subscription(), SubscriptionKind::Channel | SubscriptionKind::Pattern) {
                                         let kind_label = cmd.kind_label();
                                         if cmd.args().len() <= 1 {
@@ -230,8 +238,12 @@ impl ClusterProxy {
                                             }
                                         };
                                         while inflight > 0 {
-                                            if let Some(resp) = pending.next().await {
+                                            if let Some((resp, version)) = pending.next().await {
                                                 inflight -= 1;
+                                                if let Some(version) = version {
+                                                    codec_handle.set_version(version);
+                                                    _resp3_negotiated = version == RespVersion::Resp3;
+                                                }
                                                 sink.send(resp).await?;
                                             } else {
                                                 inflight = 0;
@@ -291,7 +303,7 @@ impl ClusterProxy {
                                             kind_label,
                                             success,
                                         );
-                                        let fut = async move { response };
+                                        let fut = async move { (response, None) };
                                         pending.push_back(Box::pin(fut));
                                         inflight += 1;
                                         continue;
@@ -302,7 +314,7 @@ impl ClusterProxy {
                                             cmd.kind_label(),
                                             true,
                                         );
-                                        let fut = async move { response };
+                                        let fut = async move { (response, None) };
                                         pending.push_back(Box::pin(fut));
                                         inflight += 1;
                                         continue;
@@ -314,7 +326,7 @@ impl ClusterProxy {
                                             cmd.kind_label(),
                                             success,
                                         );
-                                        let fut = async move { response };
+                                        let fut = async move { (response, None) };
                                         pending.push_back(Box::pin(fut));
                                         inflight += 1;
                                         continue;
@@ -326,21 +338,31 @@ impl ClusterProxy {
                                             cmd.kind_label(),
                                             success,
                                         );
-                                        let fut = async move { response };
+                                        let fut = async move { (response, None) };
                                         pending.push_back(Box::pin(fut));
                                         inflight += 1;
                                         continue;
                                     }
+                                    let requested_version = cmd.resp_version_request();
                                     let guard = self.prepare_dispatch(client_id, cmd);
-                                    pending.push_back(Box::pin(guard));
+                                    let fut = async move {
+                                        let resp = guard.await;
+                                        let version = if !resp.is_error() {
+                                            requested_version
+                                        } else {
+                                            None
+                                        };
+                                        (resp, version)
+                                    };
+                                    pending.push_back(Box::pin(fut));
                                     inflight += 1;
                                 }
                                 Err(err) => {
                                     metrics::global_error_incr();
                                     metrics::front_error(self.cluster.as_ref(), "parse");
                                     metrics::front_command(self.cluster.as_ref(), "invalid", false);
                                     let message = Bytes::from(format!("ERR {err}"));
-                                    let fut = async move { RespValue::Error(message) };
+                                    let fut = async move { (RespValue::Error(message), None) };
                                     pending.push_back(Box::pin(fut));
                                     inflight += 1;
                                 }
@@ -364,7 +386,11 @@ impl ClusterProxy {
             }
         }
 
-        while let Some(resp) = pending.next().await {
+        while let Some((resp, version)) = pending.next().await {
+            if let Some(version) = version {
+                codec_handle.set_version(version);
+                _resp3_negotiated = version == RespVersion::Resp3;
+            }
             sink.send(resp).await?;
         }
         sink.close().await?;
@@ -903,13 +929,15 @@ struct ClusterConnector {
     heartbeat_interval: Duration,
     reconnect_base_delay: Duration,
     max_reconnect_attempts: usize,
+    backend_resp_version: RespVersion,
 }
 
 impl ClusterConnector {
     fn new(
         runtime: Arc<ClusterRuntime>,
         default_timeout_ms: u64,
         backend_auth: Option<BackendAuth>,
+        backend_resp_version: RespVersion,
     ) -> Self {
         Self {
             runtime,
@@ -918,6 +946,7 @@ impl ClusterConnector {
             heartbeat_interval: Duration::from_secs(30),
             reconnect_base_delay: Duration::from_millis(50),
             max_reconnect_attempts: 3,
+            backend_resp_version,
         }
     }
 
@@ -950,11 +979,91 @@ impl ClusterConnector {
         Ok(framed)
     }
 
+    async fn negotiate_resp_version(
+        &self,
+        cluster: &str,
+        node: &BackendNode,
+        framed: &mut Framed<TcpStream, RespCodec>,
+    ) -> Result<RespVersion> {
+        framed.codec_mut().set_version(RespVersion::Resp2);
+        if self.backend_resp_version != RespVersion::Resp3 {
+            return Ok(RespVersion::Resp2);
+        }
+
+        let timeout_duration = self.current_timeout();
+        let mut hello_parts = vec![
+            RespValue::BulkString(Bytes::from_static(b"HELLO")),
+            RespValue::BulkString(Bytes::from_static(b"3")),
+        ];
+        if let Some(auth) = &self.backend_auth {
+            if let Some((username, password)) = auth.hello_credentials() {
+                hello_parts.push(RespValue::BulkString(Bytes::from_static(b"AUTH")));
+                hello_parts.push(RespValue::BulkString(username));
+                hello_parts.push(RespValue::BulkString(password));
+            }
+        }
+        let hello = RespValue::Array(hello_parts);
+
+        match timeout(timeout_duration, framed.send(hello)).await {
+            Ok(Ok(())) => {}
+            Ok(Err(err)) => {
+                metrics::backend_error(cluster, node.as_str(), "resp3_handshake");
+                return Err(err.context(format!("failed to send RESP3 HELLO to {}", node.as_str())));
+            }
+            Err(_) => {
+                metrics::backend_error(cluster, node.as_str(), "resp3_handshake");
+                return Err(anyhow!(
+                    "backend {} timed out sending RESP3 HELLO",
+                    node.as_str()
+                ));
+            }
+        }
+
+        let reply = match timeout(timeout_duration, framed.next()).await {
+            Ok(Some(Ok(value))) => value,
+            Ok(Some(Err(err))) => {
+                metrics::backend_error(cluster, node.as_str(), "resp3_handshake");
+                return Err(err.context(format!(
+                    "failed to read RESP3 HELLO reply from {}",
+                    node.as_str()
+                )));
+            }
+            Ok(None) => {
+                metrics::backend_error(cluster, node.as_str(), "resp3_handshake");
+                return Err(anyhow!(
+                    "backend {} closed connection during RESP3 HELLO",
+                    node.as_str()
+                ));
+            }
+            Err(_) => {
+                metrics::backend_error(cluster, node.as_str(), "resp3_handshake");
+                return Err(anyhow!(
+                    "backend {} timed out waiting for RESP3 HELLO reply",
+                    node.as_str()
+                ));
+            }
+        };
+
+        if reply.is_error() {
+            info!(
+                cluster = %cluster,
+                backend = %node.as_str(),
+                "backend rejected RESP3 HELLO; falling back to RESP2"
+            );
+            framed.codec_mut().set_version(RespVersion::Resp2);
+            return Ok(RespVersion::Resp2);
+        }
+
+        framed.codec_mut().set_version(RespVersion::Resp3);
+        Ok(RespVersion::Resp3)
+    }
+
     async fn execute(
         &self,
         framed: &mut Framed<TcpStream, RespCodec>,
         command: RedisCommand,
     ) -> Result<RespValue> {
+        let requested_version = command.resp_version_request();
         let blocking = command.as_blocking();
         if let Ok(name) = std::str::from_utf8(command.command_name()) {
             if name.eq_ignore_ascii_case("blpop") || name.eq_ignore_ascii_case("brpop") {
@@ -966,7 +1075,7 @@ impl ClusterConnector {
             .await
             .context("timed out sending command")??;
 
-        match blocking {
+        let response = match blocking {
             BlockingKind::Queue { .. } | BlockingKind::Stream { .. } => match framed.next().await {
                 Some(Ok(value)) => Ok(value),
                 Some(Err(err)) => Err(err.into()),
@@ -978,7 +1087,14 @@ impl ClusterConnector {
                 Ok(None) => Err(anyhow!("backend closed connection")),
                 Err(_) => Err(anyhow!("timed out waiting for response")),
             },
+        }?;
+
+        if let Some(version) = requested_version {
+            if !response.is_error() {
+                framed.codec_mut().set_version(version);
+            }
         }
+        Ok(response)
     }
 
     async fn connect_with_retry(
@@ -990,15 +1106,33 @@ impl ClusterConnector {
         for attempt in 0..self.max_reconnect_attempts {
             let attempt_start = Instant::now();
             match self.open_stream(node.as_str()).await {
-                Ok(stream) => {
+                Ok(mut stream) => {
                     metrics::backend_probe_duration(
                         cluster,
                         node.as_str(),
                         "connect",
                         attempt_start.elapsed(),
                     );
                     metrics::backend_probe_result(cluster, node.as_str(), "connect", true);
-                    return Ok(stream);
+                    match self
+                        .negotiate_resp_version(cluster, node, &mut stream)
+                        .await
+                    {
+                        Ok(_) => return Ok(stream),
+                        Err(err) => {
+                            warn!(
+                                cluster = %cluster,
+                                backend = %node.as_str(),
+                                attempt = attempt + 1,
+                                error = %err,
+                                "failed to negotiate RESP version with backend"
+                            );
+                            last_error = Some(err);
+                            if attempt + 1 < self.max_reconnect_attempts {
+                                sleep(self.reconnect_base_delay).await;
+                            }
+                        }
+                    }
                 }
                 Err(err) => {
                     let elapsed = attempt_start.elapsed();