[fix](trx-client): harden json tcp parsing and io limits

Add typed remote endpoint parsing (including bracketed IPv6), bounded JSON line reads, and read/write/request timeouts across client/server JSON-TCP paths.

Co-authored-by: OpenAI Codex <codex@openai.com>
Signed-off-by: Stanislaw Grams <stanislawgrams@gmail.com>

src/trx-client/src/main.rs

@@ -164,7 +164,7 @@ async fn async_init() -> DynResult<AppState> {
         .or_else(|| cfg.remote.url.clone())
         .ok_or("Remote URL not specified. Use --url or set [remote].url in config.")?;
 
-    let remote_addr =
+    let remote_endpoint =
         parse_remote_url(&remote_url).map_err(|e| format!("Invalid remote URL: {}", e))?;
 
     let remote_token = cli.token.clone().or_else(|| cfg.remote.auth.token.clone());
@@ -216,7 +216,7 @@ async fn async_init() -> DynResult<AppState> {
 
     info!(
         "Starting trx-client (remote: {}, frontends: {})",
-        remote_addr,
+        remote_endpoint.connect_addr(),
         frontends.join(", ")
     );
 
@@ -228,14 +228,10 @@ async fn async_init() -> DynResult<AppState> {
     let (state_tx, state_rx) = watch::channel(initial_state);
 
     // Extract host for audio before moving remote_addr
-    let remote_host = remote_addr
+    let remote_host = remote_endpoint.host.clone();
-        .split(':')
-        .next()
-        .unwrap_or("127.0.0.1")
-        .to_string();
 
     let remote_cfg = RemoteClientConfig {
-        addr: remote_addr,
+        addr: remote_endpoint.connect_addr(),
         token: remote_token,
         poll_interval: Duration::from_millis(poll_interval_ms),
     };

src/trx-client/src/remote_client.rs

@@ -4,7 +4,7 @@
 
 use std::time::Duration;
 
-use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+use tokio::io::{AsyncBufRead, AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::net::TcpStream;
 use tokio::sync::{mpsc, watch};
 use tokio::time::{self, Instant};
@@ -16,6 +16,27 @@ use trx_core::{RigError, RigResult};
 use trx_protocol::rig_command_to_client;
 use trx_protocol::{ClientCommand, ClientEnvelope, ClientResponse};
 
+const DEFAULT_REMOTE_PORT: u16 = 4532;
+const CONNECT_TIMEOUT: Duration = Duration::from_secs(5);
+const IO_TIMEOUT: Duration = Duration::from_secs(10);
+const MAX_JSON_LINE_BYTES: usize = 16 * 1024;
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub struct RemoteEndpoint {
+    pub host: String,
+    pub port: u16,
+}
+
+impl RemoteEndpoint {
+    pub fn connect_addr(&self) -> String {
+        if self.host.contains(':') && !self.host.starts_with('[') {
+            format!("[{}]:{}", self.host, self.port)
+        } else {
+            format!("{}:{}", self.host, self.port)
+        }
+    }
+}
+
 pub struct RemoteClientConfig {
     pub addr: String,
     pub token: Option<String>,
@@ -37,17 +58,20 @@ pub async fn run_remote_client(
         }
 
         info!("Remote client: connecting to {}", config.addr);
-        match TcpStream::connect(&config.addr).await {
+        match time::timeout(CONNECT_TIMEOUT, TcpStream::connect(&config.addr)).await {
-            Ok(stream) => {
+            Ok(Ok(stream)) => {
                 if let Err(e) =
                     handle_connection(&config, stream, &mut rx, &state_tx, &mut shutdown_rx).await
                 {
                     warn!("Remote connection dropped: {}", e);
                 }
             }
-            Err(e) => {
+            Ok(Err(e)) => {
                 warn!("Remote connect failed: {}", e);
             }
+            Err(_) => {
+                warn!("Remote connect timed out after {:?}", CONNECT_TIMEOUT);
+            }
         }
 
         tokio::select! {
@@ -128,20 +152,23 @@ async fn send_command(
     let payload = serde_json::to_string(&envelope)
         .map_err(|e| RigError::communication(format!("JSON serialize failed: {e}")))?;
 
-    writer
+    time::timeout(
-        .write_all(format!("{}\n", payload).as_bytes())
+        IO_TIMEOUT,
-        .await
+        writer.write_all(format!("{}\n", payload).as_bytes()),
-        .map_err(|e| RigError::communication(format!("write failed: {e}")))?;
+    )
-    writer
+    .await
-        .flush()
+    .map_err(|_| RigError::communication(format!("write timed out after {:?}", IO_TIMEOUT)))?
+    .map_err(|e| RigError::communication(format!("write failed: {e}")))?;
+    time::timeout(IO_TIMEOUT, writer.flush())
         .await
+        .map_err(|_| RigError::communication(format!("flush timed out after {:?}", IO_TIMEOUT)))?
         .map_err(|e| RigError::communication(format!("flush failed: {e}")))?;
 
-    let mut line = String::new();
+    let line = time::timeout(IO_TIMEOUT, read_limited_line(reader, MAX_JSON_LINE_BYTES))
-    reader
-        .read_line(&mut line)
         .await
+        .map_err(|_| RigError::communication(format!("read timed out after {:?}", IO_TIMEOUT)))?
         .map_err(|e| RigError::communication(format!("read failed: {e}")))?;
+    let line = line.ok_or_else(|| RigError::communication("connection closed by remote"))?;
 
     let resp: ClientResponse = serde_json::from_str(line.trim_end())
         .map_err(|e| RigError::communication(format!("invalid response: {e}")))?;
@@ -159,7 +186,59 @@ async fn send_command(
     ))
 }
 
-pub fn parse_remote_url(url: &str) -> Result<String, String> {
+async fn read_limited_line<R: AsyncBufRead + Unpin>(
+    reader: &mut R,
+    max_bytes: usize,
+) -> std::io::Result<Option<String>> {
+    let mut line = Vec::with_capacity(256);
+    loop {
+        let available = reader.fill_buf().await?;
+        if available.is_empty() {
+            if line.is_empty() {
+                return Ok(None);
+            }
+            let text = String::from_utf8(line).map_err(|e| {
+                std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line is not valid UTF-8: {e}"),
+                )
+            })?;
+            return Ok(Some(text));
+        }
+
+        if let Some(pos) = available.iter().position(|b| *b == b'\n') {
+            let chunk = &available[..=pos];
+            if line.len() + chunk.len() > max_bytes {
+                return Err(std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line exceeds maximum size of {max_bytes} bytes"),
+                ));
+            }
+            line.extend_from_slice(chunk);
+            reader.consume(pos + 1);
+            let text = String::from_utf8(line).map_err(|e| {
+                std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line is not valid UTF-8: {e}"),
+                )
+            })?;
+            return Ok(Some(text));
+        }
+
+        if line.len() + available.len() > max_bytes {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                format!("line exceeds maximum size of {max_bytes} bytes"),
+            ));
+        }
+
+        line.extend_from_slice(available);
+        let consumed = available.len();
+        reader.consume(consumed);
+    }
+}
+
+pub fn parse_remote_url(url: &str) -> Result<RemoteEndpoint, String> {
     let trimmed = url.trim();
     if trimmed.is_empty() {
         return Err("remote url is empty".into());
@@ -170,9 +249,107 @@ pub fn parse_remote_url(url: &str) -> Result<String, String> {
         .or_else(|| trimmed.strip_prefix("http-json://"))
         .unwrap_or(trimmed);
 
-    if !addr.contains(':') {
+    parse_host_port(addr)
-        return Ok(format!("{}:4532", addr));
+}
+
+fn parse_host_port(input: &str) -> Result<RemoteEndpoint, String> {
+    if let Some(rest) = input.strip_prefix('[') {
+        let closing = rest
+            .find(']')
+            .ok_or("invalid remote url: missing closing ']' for IPv6 host")?;
+        let host = &rest[..closing];
+        let remainder = &rest[closing + 1..];
+        if host.is_empty() {
+            return Err("invalid remote url: host is empty".into());
+        }
+        let port = if remainder.is_empty() {
+            DEFAULT_REMOTE_PORT
+        } else if let Some(port_str) = remainder.strip_prefix(':') {
+            parse_port(port_str)?
+        } else {
+            return Err("invalid remote url: expected ':<port>' after ']'".into());
+        };
+        return Ok(RemoteEndpoint {
+            host: host.to_string(),
+            port,
+        });
     }
 
-    Ok(addr.to_string())
+    if input.contains(':') {
+        if input.matches(':').count() > 1 {
+            return Err("invalid remote url: IPv6 host must be bracketed like [::1]:4532".into());
+        }
+        let (host, port_str) = input
+            .rsplit_once(':')
+            .ok_or("invalid remote url: expected host:port")?;
+        if host.is_empty() {
+            return Err("invalid remote url: host is empty".into());
+        }
+        return Ok(RemoteEndpoint {
+            host: host.to_string(),
+            port: parse_port(port_str)?,
+        });
+    }
+
+    Ok(RemoteEndpoint {
+        host: input.to_string(),
+        port: DEFAULT_REMOTE_PORT,
+    })
+}
+
+fn parse_port(port_str: &str) -> Result<u16, String> {
+    let port: u16 = port_str
+        .parse()
+        .map_err(|_| format!("invalid remote port: '{port_str}'"))?;
+    if port == 0 {
+        return Err("invalid remote port: 0".into());
+    }
+    Ok(port)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{parse_remote_url, RemoteEndpoint};
+
+    #[test]
+    fn parse_host_default_port() {
+        let parsed = parse_remote_url("example.local").expect("must parse");
+        assert_eq!(
+            parsed,
+            RemoteEndpoint {
+                host: "example.local".to_string(),
+                port: 4532
+            }
+        );
+    }
+
+    #[test]
+    fn parse_ipv4_with_port() {
+        let parsed = parse_remote_url("tcp://127.0.0.1:9000").expect("must parse");
+        assert_eq!(
+            parsed,
+            RemoteEndpoint {
+                host: "127.0.0.1".to_string(),
+                port: 9000
+            }
+        );
+    }
+
+    #[test]
+    fn parse_bracketed_ipv6() {
+        let parsed = parse_remote_url("http-json://[::1]:7000").expect("must parse");
+        assert_eq!(
+            parsed,
+            RemoteEndpoint {
+                host: "::1".to_string(),
+                port: 7000
+            }
+        );
+    }
+
+    #[test]
+    fn reject_unbracketed_ipv6() {
+        let err = parse_remote_url("::1:7000").expect_err("must fail");
+        assert!(err.contains("must be bracketed"));
+    }
 }

src/trx-client/trx-frontend/trx-frontend-http-json/src/server.rs

@@ -4,21 +4,27 @@
 
 use std::net::SocketAddr;
 use std::sync::Arc;
+use std::time::Duration;
 
-use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+use tokio::io::{AsyncBufRead, AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::net::{TcpListener, TcpStream};
 use tokio::sync::{mpsc, oneshot, watch};
 use tokio::task::JoinHandle;
+use tokio::time;
 use tracing::{error, info};
 
 use trx_core::rig::request::RigRequest;
 use trx_core::rig::state::RigState;
-use trx_frontend::{FrontendSpawner, FrontendRuntimeContext};
+use trx_frontend::{FrontendRuntimeContext, FrontendSpawner};
 use trx_protocol::auth::{SimpleTokenValidator, TokenValidator};
 use trx_protocol::codec::parse_envelope;
 use trx_protocol::mapping;
 use trx_protocol::ClientResponse;
 
+const IO_TIMEOUT: Duration = Duration::from_secs(10);
+const REQUEST_TIMEOUT: Duration = Duration::from_secs(12);
+const MAX_JSON_LINE_BYTES: usize = 16 * 1024;
+
 /// JSON-over-TCP frontend for control and status.
 pub struct HttpJsonFrontend;
 
@@ -68,17 +74,24 @@ async fn handle_client(
 ) -> std::io::Result<()> {
     let (reader, mut writer) = socket.into_split();
     let mut reader = BufReader::new(reader);
-    let mut line = String::new();
 
     loop {
-        line.clear();
+        let line = time::timeout(
-        let bytes_read = reader.read_line(&mut line).await?;
+            IO_TIMEOUT,
-        if bytes_read == 0 {
+            read_limited_line(&mut reader, MAX_JSON_LINE_BYTES),
+        )
+        .await
+        .map_err(|_| {
+            std::io::Error::new(
+                std::io::ErrorKind::TimedOut,
+                "read timeout waiting for client request",
+            )
+        })??;
+        let Some(line) = line else {
             info!("json tcp client {} disconnected", addr);
             break;
-        }
+        };
 
-        // Simple protocol: one line = one JSON command.
         let trimmed = line.trim();
         if trimmed.is_empty() {
             continue;
@@ -93,9 +106,7 @@ async fn handle_client(
                     state: None,
                     error: Some(format!("Invalid JSON: {}", e)),
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
                 continue;
             }
         };
@@ -106,13 +117,10 @@ async fn handle_client(
                 state: None,
                 error: Some(err),
             };
-            let resp_line = serde_json::to_string(&resp)? + "\n";
+            send_response(&mut writer, &resp).await?;
-            writer.write_all(resp_line.as_bytes()).await?;
-            writer.flush().await?;
             continue;
         }
 
-        // Map ClientCommand -> RigCommand using trx-protocol.
         let rig_cmd = mapping::client_command_to_rig(envelope.cmd);
 
         let (resp_tx, resp_rx) = oneshot::channel();
@@ -121,50 +129,62 @@ async fn handle_client(
             respond_to: resp_tx,
         };
 
-        if let Err(e) = tx.send(req).await {
+        match time::timeout(IO_TIMEOUT, tx.send(req)).await {
-            error!("Failed to send request to rig_task: {:?}", e);
+            Ok(Ok(())) => {}
-            let resp = ClientResponse {
+            Ok(Err(e)) => {
-                success: false,
+                error!("Failed to send request to rig_task: {:?}", e);
-                state: None,
+                let resp = ClientResponse {
-                error: Some("Internal error: rig task not available".into()),
+                    success: false,
-            };
+                    state: None,
-            let resp_line = serde_json::to_string(&resp)? + "\n";
+                    error: Some("Internal error: rig task not available".into()),
-            writer.write_all(resp_line.as_bytes()).await?;
+                };
-            writer.flush().await?;
+                send_response(&mut writer, &resp).await?;
-            continue;
+                continue;
+            }
+            Err(_) => {
+                let resp = ClientResponse {
+                    success: false,
+                    state: None,
+                    error: Some("Internal error: request queue timeout".into()),
+                };
+                send_response(&mut writer, &resp).await?;
+                continue;
+            }
         }
 
-        match resp_rx.await {
+        match time::timeout(REQUEST_TIMEOUT, resp_rx).await {
-            Ok(Ok(snapshot)) => {
+            Ok(Ok(Ok(snapshot))) => {
                 let resp = ClientResponse {
                     success: true,
                     state: Some(snapshot),
                     error: None,
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
             }
-            Ok(Err(err)) => {
+            Ok(Ok(Err(err))) => {
                 let resp = ClientResponse {
                     success: false,
                     state: None,
                     error: Some(err.message),
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
             }
-            Err(e) => {
+            Ok(Err(e)) => {
                 error!("Rig response oneshot recv error: {:?}", e);
                 let resp = ClientResponse {
                     success: false,
                     state: None,
                     error: Some("Internal error waiting for rig response".into()),
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
+            }
-                writer.flush().await?;
+            Err(_) => {
+                let resp = ClientResponse {
+                    success: false,
+                    state: None,
+                    error: Some("Request timed out waiting for rig response".into()),
+                };
+                send_response(&mut writer, &resp).await?;
             }
         }
     }
@@ -172,6 +192,76 @@ async fn handle_client(
     Ok(())
 }
 
+async fn read_limited_line<R: AsyncBufRead + Unpin>(
+    reader: &mut R,
+    max_bytes: usize,
+) -> std::io::Result<Option<String>> {
+    let mut line = Vec::with_capacity(256);
+    loop {
+        let available = reader.fill_buf().await?;
+        if available.is_empty() {
+            if line.is_empty() {
+                return Ok(None);
+            }
+            let text = String::from_utf8(line).map_err(|e| {
+                std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line is not valid UTF-8: {e}"),
+                )
+            })?;
+            return Ok(Some(text));
+        }
+
+        if let Some(pos) = available.iter().position(|b| *b == b'\n') {
+            let chunk = &available[..=pos];
+            if line.len() + chunk.len() > max_bytes {
+                return Err(std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line exceeds maximum size of {max_bytes} bytes"),
+                ));
+            }
+            line.extend_from_slice(chunk);
+            reader.consume(pos + 1);
+            let text = String::from_utf8(line).map_err(|e| {
+                std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line is not valid UTF-8: {e}"),
+                )
+            })?;
+            return Ok(Some(text));
+        }
+
+        if line.len() + available.len() > max_bytes {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                format!("line exceeds maximum size of {max_bytes} bytes"),
+            ));
+        }
+
+        line.extend_from_slice(available);
+        let consumed = available.len();
+        reader.consume(consumed);
+    }
+}
+
+async fn send_response(
+    writer: &mut tokio::net::tcp::OwnedWriteHalf,
+    response: &ClientResponse,
+) -> std::io::Result<()> {
+    let resp_line = serde_json::to_string(response).map_err(std::io::Error::other)? + "\n";
+    time::timeout(IO_TIMEOUT, writer.write_all(resp_line.as_bytes()))
+        .await
+        .map_err(|_| {
+            std::io::Error::new(std::io::ErrorKind::TimedOut, "response write timeout")
+        })??;
+    time::timeout(IO_TIMEOUT, writer.flush())
+        .await
+        .map_err(|_| {
+            std::io::Error::new(std::io::ErrorKind::TimedOut, "response flush timeout")
+        })??;
+    Ok(())
+}
+
 fn authorize(token: &Option<String>, context: &FrontendRuntimeContext) -> Result<(), String> {
     let validator = SimpleTokenValidator::new(context.auth_tokens.clone());
     validator.validate(token)

src/trx-server/src/listener.rs

@@ -10,10 +10,12 @@
 use std::collections::HashSet;
 use std::net::SocketAddr;
 use std::sync::Arc;
+use std::time::Duration;
 
-use tokio::io::{AsyncBufReadExt, AsyncWriteExt, BufReader};
+use tokio::io::{AsyncBufRead, AsyncBufReadExt, AsyncWriteExt, BufReader};
 use tokio::net::{TcpListener, TcpStream};
 use tokio::sync::{mpsc, oneshot, watch};
+use tokio::time;
 use tracing::{error, info};
 
 use trx_core::rig::command::RigCommand;
@@ -24,6 +26,10 @@ use trx_protocol::codec::parse_envelope;
 use trx_protocol::mapping;
 use trx_protocol::ClientResponse;
 
+const IO_TIMEOUT: Duration = Duration::from_secs(10);
+const REQUEST_TIMEOUT: Duration = Duration::from_secs(12);
+const MAX_JSON_LINE_BYTES: usize = 16 * 1024;
+
 /// Run the JSON TCP listener, accepting client connections.
 pub async fn run_listener(
     addr: SocketAddr,
@@ -68,6 +74,76 @@ pub async fn run_listener(
     Ok(())
 }
 
+async fn read_limited_line<R: AsyncBufRead + Unpin>(
+    reader: &mut R,
+    max_bytes: usize,
+) -> std::io::Result<Option<String>> {
+    let mut line = Vec::with_capacity(256);
+    loop {
+        let available = reader.fill_buf().await?;
+        if available.is_empty() {
+            if line.is_empty() {
+                return Ok(None);
+            }
+            let text = String::from_utf8(line).map_err(|e| {
+                std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line is not valid UTF-8: {e}"),
+                )
+            })?;
+            return Ok(Some(text));
+        }
+
+        if let Some(pos) = available.iter().position(|b| *b == b'\n') {
+            let chunk = &available[..=pos];
+            if line.len() + chunk.len() > max_bytes {
+                return Err(std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line exceeds maximum size of {max_bytes} bytes"),
+                ));
+            }
+            line.extend_from_slice(chunk);
+            reader.consume(pos + 1);
+            let text = String::from_utf8(line).map_err(|e| {
+                std::io::Error::new(
+                    std::io::ErrorKind::InvalidData,
+                    format!("line is not valid UTF-8: {e}"),
+                )
+            })?;
+            return Ok(Some(text));
+        }
+
+        if line.len() + available.len() > max_bytes {
+            return Err(std::io::Error::new(
+                std::io::ErrorKind::InvalidData,
+                format!("line exceeds maximum size of {max_bytes} bytes"),
+            ));
+        }
+
+        line.extend_from_slice(available);
+        let consumed = available.len();
+        reader.consume(consumed);
+    }
+}
+
+async fn send_response(
+    writer: &mut tokio::net::tcp::OwnedWriteHalf,
+    response: &ClientResponse,
+) -> std::io::Result<()> {
+    let resp_line = serde_json::to_string(response).map_err(std::io::Error::other)? + "\n";
+    time::timeout(IO_TIMEOUT, writer.write_all(resp_line.as_bytes()))
+        .await
+        .map_err(|_| {
+            std::io::Error::new(std::io::ErrorKind::TimedOut, "response write timeout")
+        })??;
+    time::timeout(IO_TIMEOUT, writer.flush())
+        .await
+        .map_err(|_| {
+            std::io::Error::new(std::io::ErrorKind::TimedOut, "response flush timeout")
+        })??;
+    Ok(())
+}
+
 async fn handle_client(
     socket: TcpStream,
     addr: SocketAddr,
@@ -78,12 +154,21 @@ async fn handle_client(
 ) -> std::io::Result<()> {
     let (reader, mut writer) = socket.into_split();
     let mut reader = BufReader::new(reader);
-    let mut line = String::new();
 
     loop {
-        line.clear();
+        let line = tokio::select! {
-        let bytes_read = tokio::select! {
+            read = time::timeout(IO_TIMEOUT, read_limited_line(&mut reader, MAX_JSON_LINE_BYTES)) => {
-            read = reader.read_line(&mut line) => read?,
+                match read {
+                    Ok(Ok(line)) => line,
+                    Ok(Err(e)) => return Err(e),
+                    Err(_) => {
+                        return Err(std::io::Error::new(
+                            std::io::ErrorKind::TimedOut,
+                            "read timeout waiting for client request",
+                        ));
+                    }
+                }
+            }
             changed = shutdown_rx.changed() => {
                 match changed {
                     Ok(()) if *shutdown_rx.borrow() => {
@@ -95,10 +180,10 @@ async fn handle_client(
                 }
             }
         };
-        if bytes_read == 0 {
+        let Some(line) = line else {
             info!("Client {} disconnected", addr);
             break;
-        }
+        };
 
         let trimmed = line.trim();
         if trimmed.is_empty() {
@@ -114,9 +199,7 @@ async fn handle_client(
                     state: None,
                     error: Some(format!("Invalid JSON: {}", e)),
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
                 continue;
             }
         };
@@ -127,9 +210,7 @@ async fn handle_client(
                 state: None,
                 error: Some(err),
             };
-            let resp_line = serde_json::to_string(&resp)? + "\n";
+            send_response(&mut writer, &resp).await?;
-            writer.write_all(resp_line.as_bytes()).await?;
-            writer.flush().await?;
             continue;
         }
 
@@ -145,9 +226,7 @@ async fn handle_client(
                     state: Some(snapshot),
                     error: None,
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
                 continue;
             }
         }
@@ -158,21 +237,44 @@ async fn handle_client(
             respond_to: resp_tx,
         };
 
-        if let Err(e) = tx.send(req).await {
+        match time::timeout(IO_TIMEOUT, tx.send(req)).await {
-            error!("Failed to send request to rig_task: {:?}", e);
+            Ok(Ok(())) => {}
-            let resp = ClientResponse {
+            Ok(Err(e)) => {
-                success: false,
+                error!("Failed to send request to rig_task: {:?}", e);
-                state: None,
+                let resp = ClientResponse {
-                error: Some("Internal error: rig task not available".into()),
+                    success: false,
-            };
+                    state: None,
-            let resp_line = serde_json::to_string(&resp)? + "\n";
+                    error: Some("Internal error: rig task not available".into()),
-            writer.write_all(resp_line.as_bytes()).await?;
+                };
-            writer.flush().await?;
+                send_response(&mut writer, &resp).await?;
-            continue;
+                continue;
+            }
+            Err(_) => {
+                let resp = ClientResponse {
+                    success: false,
+                    state: None,
+                    error: Some("Internal error: request queue timeout".into()),
+                };
+                send_response(&mut writer, &resp).await?;
+                continue;
+            }
         }
 
         match tokio::select! {
-            result = resp_rx => result,
+            result = time::timeout(REQUEST_TIMEOUT, resp_rx) => {
+                match result {
+                    Ok(inner) => inner,
+                    Err(_) => {
+                        let resp = ClientResponse {
+                            success: false,
+                            state: None,
+                            error: Some("Request timed out waiting for rig response".into()),
+                        };
+                        send_response(&mut writer, &resp).await?;
+                        continue;
+                    }
+                }
+            }
             changed = shutdown_rx.changed() => {
                 match changed {
                     Ok(()) if *shutdown_rx.borrow() => {
@@ -190,9 +292,7 @@ async fn handle_client(
                     state: Some(snapshot),
                     error: None,
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
             }
             Ok(Err(err)) => {
                 let resp = ClientResponse {
@@ -200,9 +300,7 @@ async fn handle_client(
                     state: None,
                     error: Some(err.message),
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
             }
             Err(e) => {
                 error!("Rig response oneshot recv error: {:?}", e);
@@ -211,9 +309,7 @@ async fn handle_client(
                     state: None,
                     error: Some("Internal error waiting for rig response".into()),
                 };
-                let resp_line = serde_json::to_string(&resp)? + "\n";
+                send_response(&mut writer, &resp).await?;
-                writer.write_all(resp_line.as_bytes()).await?;
-                writer.flush().await?;
             }
         }
     }