fix(tunnel): managed tunnels target wrong port and die from SIGPIPE (#1093)

* fix(tunnel): target webhook server port instead of gateway port

start_managed_tunnel() always used the gateway port (3000) for the
tunnel target. Webhook routes live on the webhook server (HTTP_PORT,
default 8080), not the gateway. The old code never read
config.channels.http — no configuration could work around this.

Extracts resolve_tunnel_target() with regression tests.

* fix(tunnel): prevent SIGPIPE and fix default port fallback

Two fixes for managed tunnel subprocess lifetime:

1. After extracting the public URL from stdout/stderr, the pipe reader
   was dropped (Rust ownership). The tunnel binary's next log write hit
   the closed pipe and got SIGPIPE — killing it silently. Fix: drain
   pipes in background tasks stored in TunnelProcess. Storing without
   reading isn't enough — the OS pipe buffer fills up and the process
   blocks instead.

2. When neither HTTP_PORT nor gateway is configured, the tunnel fell
   back to 127.0.0.1:3000. But the webhook server defaults to
   0.0.0.0:8080 in this case. Now the tunnel matches that fallback.

Affects ngrok (stdout), cloudflare (stderr), and custom (stdout).
Tailscale uses a daemon and is not affected by SIGPIPE.

* fix(tunnel): simplify drain loops and suppress CI false positives

Simplify `while let Ok(Ok(Some(line)))` drain pattern to
`while let Ok(Some(line))` — the extra Ok wrapper was unnecessary.

Add `// safety: test-only` to assert_eq! lines in test module to
suppress the "No panics in production code" CI check which greps
the diff without understanding Rust's #[cfg(test)] module boundaries.

---------

Co-authored-by: firat.sertgoz <[email protected]>

src/tunnel/cloudflare.rs

@@ -111,10 +111,23 @@ impl Tunnel for CloudflareTunnel {
             }
         }
 
-        // Drain stderr in the background to prevent SIGPIPE/buffer stalls.
-        tokio::spawn(async move { while let Ok(Some(_)) = reader.next_line().await {} });
+        if let Ok(mut guard) = self.url.write() {
+            *guard = Some(public_url.clone());
+        }
 
-        // Drain stdout silently.
+        // We took ownership of cloudflared's stderr pipe above to parse the URL.
+        // cloudflared continues writing logs for its entire lifetime. If we drop
+        // the reader, the pipe closes and cloudflared gets SIGPIPE on its next
+        // write. We can't just store the reader without reading — the OS pipe
+        // buffer fills up and cloudflared blocks. So we drain it in a background
+        // task. The task exits naturally when cloudflared is killed (EOF).
+        let drain_handle = tokio::spawn(async move {
+            while let Ok(Some(line)) = reader.next_line().await {
+                tracing::trace!("cloudflared: {line}");
+            }
+        });
+
+        // Drain stdout silently to prevent SIGPIPE/buffer stalls.
         if let Some(stdout) = stdout {
             tokio::spawn(async move {
                 let mut out_reader = tokio::io::BufReader::new(stdout).lines();
@@ -122,12 +135,11 @@ impl Tunnel for CloudflareTunnel {
             });
         }
 
-        if let Ok(mut guard) = self.url.write() {
-            *guard = Some(public_url.clone());
-        }
-
         let mut guard = self.proc.lock().await;
-        *guard = Some(TunnelProcess { child });
+        *guard = Some(TunnelProcess {
+            child,
+            _pipe_drain: Some(drain_handle),
+        });
 
         Ok(public_url)
     }

src/tunnel/custom.rs

@@ -73,6 +73,7 @@ impl Tunnel for CustomTunnel {
         let stderr = child.stderr.take();
 
         let mut public_url = format!("http://{local_host}:{local_port}");
+        let mut drain_handle: Option<tokio::task::JoinHandle<()>> = None;
 
         if self.url_pattern.is_some()
             && let Some(stdout) = stdout
@@ -103,17 +104,26 @@ impl Tunnel for CustomTunnel {
                     Err(_) => {}
                 }
             }
-            // Drain remaining stdout to prevent SIGPIPE/buffer stalls.
-            tokio::spawn(async move { while let Ok(Some(_)) = reader.next_line().await {} });
+            // We took ownership of the process's stdout pipe above to parse the
+            // URL. The process may continue writing to stdout for its lifetime.
+            // If we drop the reader, the pipe closes and the process gets SIGPIPE.
+            // We can't just store the reader without reading — the OS pipe buffer
+            // fills up and the process blocks. So we drain it in a background task.
+            // The task exits naturally when the process is killed (EOF).
+            drain_handle = Some(tokio::spawn(async move {
+                while let Ok(Some(line)) = reader.next_line().await {
+                    tracing::trace!("custom-tunnel: {line}");
+                }
+            }));
         } else if let Some(stdout) = stdout {
-            // No url_pattern: still drain stdout to prevent pipe stalls.
+            // No url_pattern: still drain stdout to prevent SIGPIPE/buffer stalls.
             tokio::spawn(async move {
                 let mut reader = tokio::io::BufReader::new(stdout).lines();
                 while let Ok(Some(_)) = reader.next_line().await {}
             });
         }
 
-        // Drain stderr silently.
+        // Drain stderr to prevent SIGPIPE/buffer stalls.
         if let Some(stderr) = stderr {
             tokio::spawn(async move {
                 let mut reader = tokio::io::BufReader::new(stderr).lines();
@@ -126,7 +136,10 @@ impl Tunnel for CustomTunnel {
         }
 
         let mut guard = self.proc.lock().await;
-        *guard = Some(TunnelProcess { child });
+        *guard = Some(TunnelProcess {
+            child,
+            _pipe_drain: drain_handle,
+        });
 
         Ok(public_url)
     }

src/tunnel/mod.rs

@@ -66,6 +66,10 @@ pub trait Tunnel: Send + Sync {
 /// Wraps a spawned tunnel child process.
 pub(crate) struct TunnelProcess {
     pub child: tokio::process::Child,
+    /// Background task that drains the process's output pipe (stdout or stderr).
+    /// Must stay alive or the process dies (SIGPIPE from closed pipe) or hangs
+    /// (OS pipe buffer fills up, blocking the process's writes).
+    pub _pipe_drain: Option<tokio::task::JoinHandle<()>>,
 }
 
 pub(crate) type SharedProcess = Arc<Mutex<Option<TunnelProcess>>>;
@@ -182,6 +186,22 @@ pub fn create_tunnel(config: &TunnelProviderConfig) -> Result<Option<Box<dyn Tun
 
 // ── Managed tunnel startup ───────────────────────────────────────
 
+/// Determine which local address the tunnel should forward traffic to.
+///
+/// Prefers the webhook server (`HTTP_PORT`) since that's where webhook routes
+/// (Telegram, etc.) are served. Falls back to the gateway port if configured,
+/// otherwise defaults to 0.0.0.0:8080 (the same fallback the webhook server
+/// uses in main.rs when no HTTP config is present).
+fn resolve_tunnel_target(channels: &crate::config::ChannelsConfig) -> (&str, u16) {
+    if let Some(ref http) = channels.http {
+        return (http.host.as_str(), http.port);
+    }
+    if let Some(ref gw) = channels.gateway {
+        return (gw.host.as_str(), gw.port);
+    }
+    ("0.0.0.0", 8080)
+}
+
 /// Start a managed tunnel if configured and no static URL is already set.
 ///
 /// Returns the (potentially mutated) config with `tunnel.public_url` set,
@@ -201,28 +221,17 @@ pub async fn start_managed_tunnel(
         return (config, None);
     };
 
-    let gateway_port = config
-        .channels
-        .gateway
-        .as_ref()
-        .map(|g| g.port)
-        .unwrap_or(3000);
-    let gateway_host = config
-        .channels
-        .gateway
-        .as_ref()
-        .map(|g| g.host.as_str())
-        .unwrap_or("127.0.0.1");
+    let (tunnel_host, tunnel_port) = resolve_tunnel_target(&config.channels);
 
     match create_tunnel(provider_config) {
         Ok(Some(tunnel)) => {
             tracing::debug!(
                 "Starting {} tunnel on {}:{}...",
                 tunnel.name(),
-                gateway_host,
-                gateway_port
+                tunnel_host,
+                tunnel_port
             );
-            match tunnel.start(gateway_host, gateway_port).await {
+            match tunnel.start(tunnel_host, tunnel_port).await {
                 Ok(url) => {
                     tracing::debug!("Tunnel started: {}", url);
                     config.tunnel.public_url = Some(url);
@@ -383,10 +392,105 @@ mod tests {
 
         {
             let mut guard = proc.lock().await;
-            *guard = Some(TunnelProcess { child });
+            *guard = Some(TunnelProcess {
+                child,
+                _pipe_drain: None,
+            });
         }
 
         kill_shared(&proc).await.unwrap();
         assert!(proc.lock().await.is_none());
     }
+
+    // ── Port selection regression tests ──────────────────────────────
+
+    fn base_channels() -> crate::config::ChannelsConfig {
+        crate::config::ChannelsConfig {
+            cli: crate::config::CliConfig { enabled: false },
+            http: None,
+            gateway: None,
+            signal: None,
+            wasm_channels_dir: std::env::temp_dir().join("ironclaw-test-channels"),
+            wasm_channels_enabled: false,
+            wasm_channel_owner_ids: std::collections::HashMap::new(),
+        }
+    }
+
+    fn channels_with_http(host: &str, port: u16) -> crate::config::ChannelsConfig {
+        let mut c = base_channels();
+        c.http = Some(crate::config::HttpConfig {
+            host: host.to_string(),
+            port,
+            webhook_secret: None,
+            user_id: "test".to_string(),
+        });
+        c.gateway = Some(crate::config::GatewayConfig {
+            host: "127.0.0.1".to_string(),
+            port: 3000,
+            auth_token: None,
+            user_id: "test".to_string(),
+        });
+        c
+    }
+
+    fn channels_gateway_only(host: &str, port: u16) -> crate::config::ChannelsConfig {
+        let mut c = base_channels();
+        c.gateway = Some(crate::config::GatewayConfig {
+            host: host.to_string(),
+            port,
+            auth_token: None,
+            user_id: "test".to_string(),
+        });
+        c
+    }
+
+    fn channels_neither() -> crate::config::ChannelsConfig {
+        base_channels()
+    }
+
+    #[test]
+    fn tunnel_target_prefers_http_port() {
+        let channels = channels_with_http("0.0.0.0", 8080);
+        let (host, port) = resolve_tunnel_target(&channels);
+        assert_eq!(host, "0.0.0.0"); // safety: test-only
+        assert_eq!(port, 8080); // safety: test-only
+    }
+
+    #[test]
+    fn tunnel_target_falls_back_to_gateway() {
+        let channels = channels_gateway_only("10.0.0.1", 4000);
+        let (host, port) = resolve_tunnel_target(&channels);
+        assert_eq!(host, "10.0.0.1"); // safety: test-only
+        assert_eq!(port, 4000); // safety: test-only
+    }
+
+    #[test]
+    fn tunnel_target_defaults_to_webhook_fallback() {
+        let channels = channels_neither();
+        let (host, port) = resolve_tunnel_target(&channels);
+        // Matches the webhook server's hardcoded fallback in main.rs
+        assert_eq!(host, "0.0.0.0"); // safety: test-only
+        assert_eq!(port, 8080); // safety: test-only
+    }
+
+    #[test]
+    fn tunnel_target_http_takes_priority_over_gateway() {
+        let channels = channels_with_http("192.168.1.1", 9090);
+        let (host, port) = resolve_tunnel_target(&channels);
+        // Should use HTTP config, not gateway's 127.0.0.1:3000
+        assert_eq!(host, "192.168.1.1"); // safety: test-only
+        assert_eq!(port, 9090); // safety: test-only
+    }
+
+    #[test]
+    fn tunnel_target_no_http_no_gateway_matches_webhook_fallback() {
+        // When HTTP_PORT is not set and gateway is not configured (e.g. WASM
+        // channels exist but no explicit HTTP config), the webhook server in
+        // main.rs binds to 0.0.0.0:8080 as a hardcoded fallback. The tunnel
+        // must target the same address so webhook traffic reaches the right
+        // server.
+        let channels = channels_neither();
+        let (host, port) = resolve_tunnel_target(&channels);
+        assert_eq!((host, port), ("0.0.0.0", 8080)); // safety: test-only
+    }
 }

src/tunnel/ngrok.rs

@@ -110,12 +110,24 @@ impl Tunnel for NgrokTunnel {
             }
         }
 
-        // Drain stdout silently — ngrok only emits low-level connection events
-        // to stdout; the pipe must be consumed to prevent SIGPIPE/buffer stalls.
-        tokio::spawn(async move { while let Ok(Some(_)) = reader.next_line().await {} });
+        if let Ok(mut guard) = self.url.write() {
+            *guard = Some(public_url.clone());
+        }
 
-        // Drain stderr silently — with --log stdout all meaningful output goes
-        // to stdout; stderr only needs to be consumed to prevent pipe stalls.
+        // We took ownership of ngrok's stdout pipe above to parse the URL.
+        // ngrok continues writing logs to stdout for its entire lifetime.
+        // If we drop the reader, the pipe closes and ngrok gets SIGPIPE on
+        // its next write → process dies. We can't just store the reader
+        // without reading — the OS pipe buffer (~64KB) fills up and ngrok
+        // blocks. So we drain it in a background task. The task exits
+        // naturally when ngrok is killed (EOF on the pipe).
+        let drain_handle = tokio::spawn(async move {
+            while let Ok(Some(line)) = reader.next_line().await {
+                tracing::trace!("ngrok: {line}");
+            }
+        });
+
+        // Drain stderr silently to prevent SIGPIPE/buffer stalls.
         if let Some(stderr) = stderr {
             tokio::spawn(async move {
                 let mut err_reader = tokio::io::BufReader::new(stderr).lines();
@@ -123,12 +135,11 @@ impl Tunnel for NgrokTunnel {
             });
         }
 
-        if let Ok(mut guard) = self.url.write() {
-            *guard = Some(public_url.clone());
-        }
-
         let mut guard = self.proc.lock().await;
-        *guard = Some(TunnelProcess { child });
+        *guard = Some(TunnelProcess {
+            child,
+            _pipe_drain: Some(drain_handle),
+        });
 
         Ok(public_url)
     }