fix(tunnel): prevent tunnel backpressure buffering from exhausting memory and cancel stream handlers before TLS shutdown

changelog.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## 2026-03-17 - 4.8.12 - fix(tunnel)
+prevent tunnel backpressure buffering from exhausting memory and cancel stream handlers before TLS shutdown
+
+- stop self-waking and writing new frames while a flush is pending to avoid unbounded TLS session buffer growth under load
+- reorder edge and hub shutdown cleanup so stream cancellation happens before TLS close_notify, preventing handlers from blocking on dead channels
+- add load tests covering sustained large transfers, burst traffic, and rapid stream churn to verify tunnel stability
+
 ## 2026-03-17 - 4.8.11 - fix(remoteingress-core)
 stop data frame send loops promptly when stream cancellation is triggered
 

rust/crates/remoteingress-core/src/edge.rs

@@ -587,21 +587,23 @@ async fn connect_to_hub_and_run(
         }
     };
 
-    // Graceful TLS shutdown: send close_notify so the hub sees a clean disconnect
-    // instead of "peer closed connection without sending TLS close_notify".
-    let mut tls_stream = tunnel_io.into_inner();
-    let _ = tokio::time::timeout(
-        Duration::from_secs(2),
-        tls_stream.shutdown(),
-    ).await;
-
-    // Cleanup
+    // Cancel stream tokens FIRST so stream handlers exit immediately.
+    // If we TLS-shutdown first, stream handlers are stuck sending to dead channels
+    // for up to 2 seconds while the shutdown times out on a dead connection.
     connection_token.cancel();
     stun_handle.abort();
     for (_, h) in port_listeners.drain() {
         h.abort();
     }
 
+    // Graceful TLS shutdown: send close_notify so the hub sees a clean disconnect.
+    // Stream handlers are already cancelled, so no new data is being produced.
+    let mut tls_stream = tunnel_io.into_inner();
+    let _ = tokio::time::timeout(
+        Duration::from_secs(2),
+        tls_stream.shutdown(),
+    ).await;
+
     result
 }
 

rust/crates/remoteingress-core/src/hub.rs

@@ -844,17 +844,19 @@ async fn handle_edge_connection(
         }
     }
 
-    // Graceful TLS shutdown: send close_notify so the edge sees a clean disconnect
-    // instead of "peer closed connection without sending TLS close_notify".
+    // Cancel stream tokens FIRST so stream handlers exit immediately.
+    // If we TLS-shutdown first, stream handlers are stuck sending to dead channels
+    // for up to 2 seconds while the shutdown times out on a dead connection.
+    edge_token.cancel();
+    config_handle.abort();
+
+    // Graceful TLS shutdown: send close_notify so the edge sees a clean disconnect.
+    // Stream handlers are already cancelled, so no new data is being produced.
     let mut tls_stream = tunnel_io.into_inner();
     let _ = tokio::time::timeout(
         Duration::from_secs(2),
         tls_stream.shutdown(),
     ).await;
-
-    // Cleanup: cancel edge token to propagate to all child tasks
-    edge_token.cancel();
-    config_handle.abort();
     {
         let mut edges = connected.lock().await;
         edges.remove(&edge_id);

rust/crates/remoteingress-protocol/src/lib.rs

@@ -312,11 +312,12 @@ impl<S: AsyncRead + AsyncWrite + Unpin> TunnelIo<S> {
         cancel_token: &tokio_util::sync::CancellationToken,
     ) -> Poll<TunnelEvent> {
         // 1. WRITE: drain ctrl queue first, then data queue.
-        //    TLS poll_write writes plaintext to session buffer (always Ready).
-        //    Batch up to 16 frames per poll cycle.
+        //    Only write when flush is complete — otherwise the TLS session buffer
+        //    grows without bound (poll_write always returns Ready, buffering plaintext
+        //    in the TLS session even when TCP can't keep up).
         //    Safe: `self.write` and `self.stream` are disjoint fields.
         let mut writes = 0;
-        while self.write.has_work() && writes < 16 {
+        while self.write.has_work() && writes < 16 && !self.write.flush_needed {
             let from_ctrl = !self.write.ctrl_queue.is_empty();
             let frame = if from_ctrl {
                 self.write.ctrl_queue.front().unwrap()
@@ -424,10 +425,12 @@ impl<S: AsyncRead + AsyncWrite + Unpin> TunnelIo<S> {
             return Poll::Ready(TunnelEvent::Cancelled);
         }
 
-        // 6. SELF-WAKE: only when we have frames AND flush is done.
+        // 6. SELF-WAKE: only when flush is complete AND we have work.
         //    If flush is pending, the TCP write-readiness waker will notify us.
-        //    If we got new channel frames, wake to write them.
-        if got_new || (!self.write.flush_needed && self.write.has_work()) {
+        //    CRITICAL: do NOT self-wake when flush_needed — this causes unbounded
+        //    TLS session buffer growth (poll_write always accepts plaintext, but TCP
+        //    can't drain it fast enough → OOM → process killed → ECONNRESET).
+        if !self.write.flush_needed && (got_new || self.write.has_work()) {
             cx.waker().wake_by_ref();
         }
 

test/test.loadtest.node.ts

@@ -0,0 +1,393 @@
+import { expect, tap } from '@push.rocks/tapbundle';
+import * as net from 'net';
+import * as stream from 'stream';
+import * as crypto from 'crypto';
+import { RemoteIngressHub, RemoteIngressEdge } from '../ts/index.js';
+
+// ---------------------------------------------------------------------------
+// Helpers (self-contained — same patterns as test.flowcontrol.node.ts)
+// ---------------------------------------------------------------------------
+
+async function findFreePorts(count: number): Promise<number[]> {
+  const servers: net.Server[] = [];
+  const ports: number[] = [];
+  for (let i = 0; i < count; i++) {
+    const server = net.createServer();
+    await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve));
+    ports.push((server.address() as net.AddressInfo).port);
+    servers.push(server);
+  }
+  await Promise.all(servers.map((s) => new Promise<void>((resolve) => s.close(() => resolve()))));
+  return ports;
+}
+
+type TrackingServer = net.Server & { destroyAll: () => void };
+
+function startEchoServer(port: number, host: string): Promise<TrackingServer> {
+  return new Promise((resolve, reject) => {
+    const connections = new Set<net.Socket>();
+    const server = net.createServer((socket) => {
+      connections.add(socket);
+      socket.on('close', () => connections.delete(socket));
+      let proxyHeaderParsed = false;
+      let pendingBuf = Buffer.alloc(0);
+      socket.on('data', (data: Buffer) => {
+        if (!proxyHeaderParsed) {
+          pendingBuf = Buffer.concat([pendingBuf, data]);
+          const idx = pendingBuf.indexOf('\r\n');
+          if (idx !== -1) {
+            proxyHeaderParsed = true;
+            const remainder = pendingBuf.subarray(idx + 2);
+            if (remainder.length > 0) socket.write(remainder);
+          }
+          return;
+        }
+        socket.write(data);
+      });
+      socket.on('error', () => {});
+    }) as TrackingServer;
+    server.destroyAll = () => {
+      for (const conn of connections) conn.destroy();
+      connections.clear();
+    };
+    server.on('error', reject);
+    server.listen(port, host, () => resolve(server));
+  });
+}
+
+function sendAndReceive(port: number, data: Buffer, timeoutMs = 30000): Promise<Buffer> {
+  return new Promise((resolve, reject) => {
+    const chunks: Buffer[] = [];
+    let totalReceived = 0;
+    const expectedLength = data.length;
+    let settled = false;
+
+    const client = net.createConnection({ host: '127.0.0.1', port }, () => {
+      client.write(data);
+      client.end();
+    });
+
+    const timer = setTimeout(() => {
+      if (!settled) {
+        settled = true;
+        client.destroy();
+        reject(new Error(`Timeout after ${timeoutMs}ms — received ${totalReceived}/${expectedLength} bytes`));
+      }
+    }, timeoutMs);
+
+    client.on('data', (chunk: Buffer) => {
+      chunks.push(chunk);
+      totalReceived += chunk.length;
+      if (totalReceived >= expectedLength && !settled) {
+        settled = true;
+        clearTimeout(timer);
+        client.destroy();
+        resolve(Buffer.concat(chunks));
+      }
+    });
+
+    client.on('end', () => {
+      if (!settled) {
+        settled = true;
+        clearTimeout(timer);
+        resolve(Buffer.concat(chunks));
+      }
+    });
+
+    client.on('error', (err) => {
+      if (!settled) {
+        settled = true;
+        clearTimeout(timer);
+        reject(err);
+      }
+    });
+  });
+}
+
+function sha256(buf: Buffer): string {
+  return crypto.createHash('sha256').update(buf).digest('hex');
+}
+
+// ---------------------------------------------------------------------------
+// Throttle Proxy: rate-limits TCP traffic between edge and hub
+// ---------------------------------------------------------------------------
+
+class ThrottleTransform extends stream.Transform {
+  private bytesPerSec: number;
+  private bucket: number;
+  private lastRefill: number;
+  private destroyed_: boolean = false;
+
+  constructor(bytesPerSecond: number) {
+    super();
+    this.bytesPerSec = bytesPerSecond;
+    this.bucket = bytesPerSecond;
+    this.lastRefill = Date.now();
+  }
+
+  _transform(chunk: Buffer, _encoding: BufferEncoding, callback: stream.TransformCallback) {
+    if (this.destroyed_) return;
+
+    const now = Date.now();
+    const elapsed = (now - this.lastRefill) / 1000;
+    this.bucket = Math.min(this.bytesPerSec, this.bucket + elapsed * this.bytesPerSec);
+    this.lastRefill = now;
+
+    if (chunk.length <= this.bucket) {
+      this.bucket -= chunk.length;
+      callback(null, chunk);
+    } else {
+      // Not enough budget — delay the entire chunk (don't split)
+      const deficit = chunk.length - this.bucket;
+      this.bucket = 0;
+      const delayMs = Math.min((deficit / this.bytesPerSec) * 1000, 1000);
+      setTimeout(() => {
+        if (this.destroyed_) return;
+        this.lastRefill = Date.now();
+        this.bucket = 0;
+        callback(null, chunk);
+      }, delayMs);
+    }
+  }
+
+  _destroy(err: Error | null, callback: (error: Error | null) => void) {
+    this.destroyed_ = true;
+    callback(err);
+  }
+}
+
+interface ThrottleProxy {
+  server: net.Server;
+  close: () => Promise<void>;
+}
+
+async function startThrottleProxy(
+  listenPort: number,
+  targetHost: string,
+  targetPort: number,
+  bytesPerSecond: number,
+): Promise<ThrottleProxy> {
+  const connections = new Set<net.Socket>();
+  const server = net.createServer((clientSock) => {
+    connections.add(clientSock);
+    const upstream = net.createConnection({ host: targetHost, port: targetPort });
+    connections.add(upstream);
+
+    const throttleUp = new ThrottleTransform(bytesPerSecond);
+    const throttleDown = new ThrottleTransform(bytesPerSecond);
+
+    clientSock.pipe(throttleUp).pipe(upstream);
+    upstream.pipe(throttleDown).pipe(clientSock);
+
+    const cleanup = () => {
+      throttleUp.destroy();
+      throttleDown.destroy();
+      clientSock.destroy();
+      upstream.destroy();
+      connections.delete(clientSock);
+      connections.delete(upstream);
+    };
+    clientSock.on('error', cleanup);
+    upstream.on('error', cleanup);
+    throttleUp.on('error', cleanup);
+    throttleDown.on('error', cleanup);
+    clientSock.on('close', cleanup);
+    upstream.on('close', cleanup);
+  });
+
+  await new Promise<void>((resolve) => server.listen(listenPort, '127.0.0.1', resolve));
+  return {
+    server,
+    close: async () => {
+      for (const c of connections) c.destroy();
+      connections.clear();
+      await new Promise<void>((resolve) => server.close(() => resolve()));
+    },
+  };
+}
+
+// ---------------------------------------------------------------------------
+// Test state
+// ---------------------------------------------------------------------------
+
+let hub: RemoteIngressHub;
+let edge: RemoteIngressEdge;
+let echoServer: TrackingServer;
+let throttle: ThrottleProxy;
+let hubPort: number;
+let proxyPort: number;
+let edgePort: number;
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+tap.test('setup: start throttled tunnel (20 Mbit/s)', async () => {
+  [hubPort, proxyPort, edgePort] = await findFreePorts(3);
+
+  echoServer = await startEchoServer(edgePort, '127.0.0.2');
+
+  // Throttle proxy: edge → proxy → hub at 20 Mbit/s (2.5 MB/s)
+  throttle = await startThrottleProxy(proxyPort, '127.0.0.1', hubPort, 2.5 * 1024 * 1024);
+
+  hub = new RemoteIngressHub();
+  edge = new RemoteIngressEdge();
+
+  await hub.start({ tunnelPort: hubPort, targetHost: '127.0.0.2' });
+  await hub.updateAllowedEdges([
+    { id: 'test-edge', secret: 'test-secret', listenPorts: [edgePort] },
+  ]);
+
+  const connectedPromise = new Promise<void>((resolve, reject) => {
+    const timeout = setTimeout(() => reject(new Error('Edge did not connect within 10s')), 10000);
+    edge.once('tunnelConnected', () => {
+      clearTimeout(timeout);
+      resolve();
+    });
+  });
+
+  // Edge connects to proxy, not hub directly
+  await edge.start({
+    hubHost: '127.0.0.1',
+    hubPort: proxyPort,
+    edgeId: 'test-edge',
+    secret: 'test-secret',
+    bindAddress: '127.0.0.1',
+  });
+
+  await connectedPromise;
+  await new Promise((resolve) => setTimeout(resolve, 500));
+
+  const status = await edge.getStatus();
+  expect(status.connected).toBeTrue();
+});
+
+tap.test('throttled: 10 streams x 50MB each through 10MB/s tunnel', async () => {
+  const streamCount = 10;
+  const payloadSize = 50 * 1024 * 1024; // 50MB per stream = 500MB total round-trip
+
+  const promises = Array.from({ length: streamCount }, () => {
+    const data = crypto.randomBytes(payloadSize);
+    const hash = sha256(data);
+    return sendAndReceive(edgePort, data, 300000).then((received) => ({
+      sent: hash,
+      received: sha256(received),
+      sizeOk: received.length === payloadSize,
+    }));
+  });
+
+  const results = await Promise.all(promises);
+  const failures = results.filter((r) => !r.sizeOk || r.sent !== r.received);
+  expect(failures.length).toEqual(0);
+
+  const status = await edge.getStatus();
+  expect(status.connected).toBeTrue();
+});
+
+tap.test('throttled: slow consumer with 50MB does not kill other streams', async () => {
+  // Open a connection that creates massive download-direction backpressure:
+  // send 50MB but DON'T read the response — client TCP receive buffer fills
+  const slowSock = net.createConnection({ host: '127.0.0.1', port: edgePort });
+  await new Promise<void>((resolve) => slowSock.on('connect', resolve));
+  const slowData = crypto.randomBytes(50 * 1024 * 1024);
+  slowSock.write(slowData);
+  slowSock.end();
+  // Don't read — backpressure builds on the download path
+
+  // Wait for backpressure to develop
+  await new Promise((r) => setTimeout(r, 3000));
+
+  // Meanwhile, 10 normal echo streams with 50MB each must complete
+  const payload = crypto.randomBytes(50 * 1024 * 1024);
+  const hash = sha256(payload);
+  const promises = Array.from({ length: 10 }, () =>
+    sendAndReceive(edgePort, payload, 300000).then((r) => ({
+      hash: sha256(r),
+      sizeOk: r.length === payload.length,
+    }))
+  );
+  const results = await Promise.all(promises);
+  const failures = results.filter((r) => !r.sizeOk || r.hash !== hash);
+  expect(failures.length).toEqual(0);
+
+  // Tunnel still alive
+  const status = await edge.getStatus();
+  expect(status.connected).toBeTrue();
+
+  slowSock.destroy();
+});
+
+tap.test('throttled: rapid churn — 5 x 50MB long + 200 x 1MB short streams', async () => {
+  // 5 long streams (50MB each) running alongside 200 short streams (1MB each)
+  const longPayload = crypto.randomBytes(50 * 1024 * 1024);
+  const longHash = sha256(longPayload);
+  const longPromises = Array.from({ length: 5 }, () =>
+    sendAndReceive(edgePort, longPayload, 300000).then((r) => ({
+      hash: sha256(r),
+      sizeOk: r.length === longPayload.length,
+    }))
+  );
+
+  const shortPayload = crypto.randomBytes(1024 * 1024);
+  const shortHash = sha256(shortPayload);
+  const shortPromises = Array.from({ length: 200 }, () =>
+    sendAndReceive(edgePort, shortPayload, 300000).then((r) => ({
+      hash: sha256(r),
+      sizeOk: r.length === shortPayload.length,
+    }))
+  );
+
+  const [longResults, shortResults] = await Promise.all([
+    Promise.all(longPromises),
+    Promise.all(shortPromises),
+  ]);
+
+  const longFails = longResults.filter((r) => !r.sizeOk || r.hash !== longHash);
+  const shortFails = shortResults.filter((r) => !r.sizeOk || r.hash !== shortHash);
+  expect(longFails.length).toEqual(0);
+  expect(shortFails.length).toEqual(0);
+
+  const status = await edge.getStatus();
+  expect(status.connected).toBeTrue();
+});
+
+tap.test('throttled: 5 burst waves of 20 streams x 50MB each', async () => {
+  for (let wave = 0; wave < 5; wave++) {
+    const streamCount = 20;
+    const payloadSize = 50 * 1024 * 1024; // 50MB per stream = 1GB per wave
+
+    const promises = Array.from({ length: streamCount }, () => {
+      const data = crypto.randomBytes(payloadSize);
+      return sendAndReceive(edgePort, data, 300000).then((r) => r.length === payloadSize);
+    });
+
+    const results = await Promise.all(promises);
+    const ok = results.filter(Boolean).length;
+    expect(ok).toEqual(streamCount);
+
+    // Brief pause between waves
+    await new Promise((r) => setTimeout(r, 500));
+
+    const status = await edge.getStatus();
+    expect(status.connected).toBeTrue();
+  }
+});
+
+tap.test('throttled: tunnel still works after all load tests', async () => {
+  const data = crypto.randomBytes(1024);
+  const hash = sha256(data);
+  const received = await sendAndReceive(edgePort, data, 30000);
+  expect(sha256(received)).toEqual(hash);
+
+  const status = await edge.getStatus();
+  expect(status.connected).toBeTrue();
+});
+
+tap.test('teardown: stop tunnel', async () => {
+  await edge.stop();
+  await hub.stop();
+  if (throttle) await throttle.close();
+  await new Promise<void>((resolve) => echoServer.close(() => resolve()));
+});
+
+export default tap.start();

ts/00_commitinfo_data.ts

@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@serve.zone/remoteingress',
-  version: '4.8.11',
+  version: '4.8.12',
   description: 'Edge ingress tunnel for DcRouter - accepts incoming TCP connections at network edge and tunnels them to DcRouter SmartProxy preserving client IP via PROXY protocol v1.'
 }