net: fix timeouts during long writes

Add updateWriteQueueSize which updates and returns queue size
(net & tls). Make _onTimeout check whether an active write
is ongoing and if so, call _unrefTimer rather than emitting
a timeout event.

Add http & https test that checks whether long-lasting (but
active) writes timeout or can finish writing as expected.

PR-URL: https://github.com/nodejs/node/pull/15791
Fixes: https://github.com/nodejs/node/issues/15082
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>

lib/net.js

@@ -397,6 +397,14 @@ Socket.prototype.setTimeout = function(msecs, callback) {
 
 
 Socket.prototype._onTimeout = function() {
+  // `.prevWriteQueueSize` !== `.updateWriteQueueSize()` means there is
+  // an active write in progress, so we suppress the timeout.
+  const prevWriteQueueSize = this._handle.writeQueueSize;
+  if (prevWriteQueueSize > 0 &&
+      prevWriteQueueSize !== this._handle.updateWriteQueueSize()) {
+    this._unrefTimer();
+    return;
+  }
   debug('_onTimeout');
   this.emit('timeout');
 };

src/stream_wrap.cc

@@ -104,6 +104,7 @@ LibuvStreamWrap::LibuvStreamWrap(Environment* env,
 void LibuvStreamWrap::AddMethods(Environment* env,
                                  v8::Local<v8::FunctionTemplate> target,
                                  int flags) {
+  env->SetProtoMethod(target, "updateWriteQueueSize", UpdateWriteQueueSize);
   env->SetProtoMethod(target, "setBlocking", SetBlocking);
   StreamBase::AddMethods<LibuvStreamWrap>(env, target, flags);
 }
@@ -144,11 +145,14 @@ bool LibuvStreamWrap::IsIPCPipe() {
 }
 
 
-void LibuvStreamWrap::UpdateWriteQueueSize() {
+uint32_t LibuvStreamWrap::UpdateWriteQueueSize() {
   HandleScope scope(env()->isolate());
-  Local<Integer> write_queue_size =
+  uint32_t write_queue_size = stream()->write_queue_size;
-      Integer::NewFromUnsigned(env()->isolate(), stream()->write_queue_size);
+  object()->Set(env()->context(),
-  object()->Set(env()->write_queue_size_string(), write_queue_size);
+                env()->write_queue_size_string(),
+                Integer::NewFromUnsigned(env()->isolate(),
+                                         write_queue_size)).FromJust();
+  return write_queue_size;
 }
 
 
@@ -273,6 +277,16 @@ void LibuvStreamWrap::OnRead(uv_stream_t* handle,
 }
 
 
+void LibuvStreamWrap::UpdateWriteQueueSize(
+    const FunctionCallbackInfo<Value>& args) {
+  LibuvStreamWrap* wrap;
+  ASSIGN_OR_RETURN_UNWRAP(&wrap, args.Holder());
+
+  uint32_t write_queue_size = wrap->UpdateWriteQueueSize();
+  args.GetReturnValue().Set(write_queue_size);
+}
+
+
 void LibuvStreamWrap::SetBlocking(const FunctionCallbackInfo<Value>& args) {
   LibuvStreamWrap* wrap;
   ASSIGN_OR_RETURN_UNWRAP(&wrap, args.Holder());

src/stream_wrap.h

@@ -84,13 +84,15 @@ class LibuvStreamWrap : public HandleWrap, public StreamBase {
   }
 
   AsyncWrap* GetAsyncWrap() override;
-  void UpdateWriteQueueSize();
+  uint32_t UpdateWriteQueueSize();
 
   static void AddMethods(Environment* env,
                          v8::Local<v8::FunctionTemplate> target,
                          int flags = StreamBase::kFlagNone);
 
  private:
+  static void UpdateWriteQueueSize(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
   static void SetBlocking(const v8::FunctionCallbackInfo<v8::Value>& args);
 
   // Callbacks for libuv

src/tls_wrap.cc

@@ -932,6 +932,15 @@ int TLSWrap::SelectSNIContextCallback(SSL* s, int* ad, void* arg) {
 #endif  // SSL_CTRL_SET_TLSEXT_SERVERNAME_CB
 
 
+void TLSWrap::UpdateWriteQueueSize(const FunctionCallbackInfo<Value>& args) {
+  TLSWrap* wrap;
+  ASSIGN_OR_RETURN_UNWRAP(&wrap, args.Holder());
+
+  uint32_t write_queue_size = wrap->UpdateWriteQueueSize();
+  args.GetReturnValue().Set(write_queue_size);
+}
+
+
 void TLSWrap::Initialize(Local<Object> target,
                          Local<Value> unused,
                          Local<Context> context) {
@@ -958,6 +967,7 @@ void TLSWrap::Initialize(Local<Object> target,
   env->SetProtoMethod(t, "enableSessionCallbacks", EnableSessionCallbacks);
   env->SetProtoMethod(t, "destroySSL", DestroySSL);
   env->SetProtoMethod(t, "enableCertCb", EnableCertCb);
+  env->SetProtoMethod(t, "updateWriteQueueSize", UpdateWriteQueueSize);
 
   StreamBase::AddMethods<TLSWrap>(env, t, StreamBase::kFlagHasWritev);
   SSLWrap<TLSWrap>::AddMethods(env, t);

src/tls_wrap.h

@@ -188,6 +188,10 @@ class TLSWrap : public AsyncWrap,
   // If true - delivered EOF to the js-land, either after `close_notify`, or
   // after the `UV_EOF` on socket.
   bool eof_;
+
+ private:
+  static void UpdateWriteQueueSize(
+      const v8::FunctionCallbackInfo<v8::Value>& args);
 };
 
 }  // namespace node

test/sequential/test-http-keep-alive-large-write.js

@@ -0,0 +1,80 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+
+// This test assesses whether long-running writes can complete
+// or timeout because the socket is not aware that the backing
+// stream is still writing.
+// To simulate a slow client, we write a really large chunk and
+// then proceed through the following cycle:
+// 1) Receive first 'data' event and record currently written size
+// 2) Once we've read up to currently written size recorded above,
+//    we pause the stream and wait longer than the server timeout
+// 3) Socket.prototype._onTimeout triggers and should confirm
+//    that the backing stream is still active and writing
+// 4) Our timer fires, we resume the socket and start at 1)
+
+const minReadSize = 250000;
+const serverTimeout = common.platformTimeout(500);
+let offsetTimeout = common.platformTimeout(100);
+let serverConnectionHandle;
+let writeSize = 3000000;
+let didReceiveData = false;
+// this represents each cycles write size, where the cycle consists
+// of `write > read > _onTimeout`
+let currentWriteSize = 0;
+
+const server = http.createServer(common.mustCall((req, res) => {
+  const content = Buffer.alloc(writeSize, 0x44);
+
+  res.writeHead(200, {
+    'Content-Type': 'application/octet-stream',
+    'Content-Length': content.length.toString(),
+    'Vary': 'Accept-Encoding'
+  });
+
+  serverConnectionHandle = res.socket._handle;
+  res.write(content);
+  res.end();
+}));
+server.setTimeout(serverTimeout);
+server.on('timeout', () => {
+  assert.strictEqual(didReceiveData, false, 'Should not timeout');
+});
+
+server.listen(0, common.mustCall(() => {
+  http.get({
+    path: '/',
+    port: server.address().port
+  }, common.mustCall((res) => {
+    const resume = () => res.resume();
+    let receivedBufferLength = 0;
+    let firstReceivedAt;
+    res.on('data', common.mustCallAtLeast((buf) => {
+      if (receivedBufferLength === 0) {
+        currentWriteSize = Math.max(
+          minReadSize,
+          writeSize - serverConnectionHandle.writeQueueSize
+        );
+        didReceiveData = false;
+        firstReceivedAt = Date.now();
+      }
+      receivedBufferLength += buf.length;
+      if (receivedBufferLength >= currentWriteSize) {
+        didReceiveData = true;
+        writeSize = serverConnectionHandle.writeQueueSize;
+        receivedBufferLength = 0;
+        res.pause();
+        setTimeout(
+          resume,
+          serverTimeout + offsetTimeout - (Date.now() - firstReceivedAt)
+        );
+        offsetTimeout = 0;
+      }
+    }, 1));
+    res.on('end', common.mustCall(() => {
+      server.close();
+    }));
+  }));
+}));

test/sequential/test-https-keep-alive-large-write.js

@@ -0,0 +1,87 @@
+'use strict';
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const assert = require('assert');
+const fixtures = require('../common/fixtures');
+const https = require('https');
+
+// This test assesses whether long-running writes can complete
+// or timeout because the socket is not aware that the backing
+// stream is still writing.
+// To simulate a slow client, we write a really large chunk and
+// then proceed through the following cycle:
+// 1) Receive first 'data' event and record currently written size
+// 2) Once we've read up to currently written size recorded above,
+//    we pause the stream and wait longer than the server timeout
+// 3) Socket.prototype._onTimeout triggers and should confirm
+//    that the backing stream is still active and writing
+// 4) Our timer fires, we resume the socket and start at 1)
+
+const minReadSize = 250000;
+const serverTimeout = common.platformTimeout(500);
+let offsetTimeout = common.platformTimeout(100);
+let serverConnectionHandle;
+let writeSize = 2000000;
+let didReceiveData = false;
+// this represents each cycles write size, where the cycle consists
+// of `write > read > _onTimeout`
+let currentWriteSize = 0;
+
+const server = https.createServer({
+  key: fixtures.readKey('agent1-key.pem'),
+  cert: fixtures.readKey('agent1-cert.pem')
+}, common.mustCall((req, res) => {
+  const content = Buffer.alloc(writeSize, 0x44);
+
+  res.writeHead(200, {
+    'Content-Type': 'application/octet-stream',
+    'Content-Length': content.length.toString(),
+    'Vary': 'Accept-Encoding'
+  });
+
+  serverConnectionHandle = res.socket._handle;
+  res.write(content);
+  res.end();
+}));
+server.setTimeout(serverTimeout);
+server.on('timeout', () => {
+  assert.strictEqual(didReceiveData, false, 'Should not timeout');
+});
+
+server.listen(0, common.mustCall(() => {
+  https.get({
+    path: '/',
+    port: server.address().port,
+    rejectUnauthorized: false
+  }, common.mustCall((res) => {
+    const resume = () => res.resume();
+    let receivedBufferLength = 0;
+    let firstReceivedAt;
+    res.on('data', common.mustCallAtLeast((buf) => {
+      if (receivedBufferLength === 0) {
+        currentWriteSize = Math.max(
+          minReadSize,
+          writeSize - serverConnectionHandle.writeQueueSize
+        );
+        didReceiveData = false;
+        firstReceivedAt = Date.now();
+      }
+      receivedBufferLength += buf.length;
+      if (receivedBufferLength >= currentWriteSize) {
+        didReceiveData = true;
+        writeSize = serverConnectionHandle.writeQueueSize;
+        receivedBufferLength = 0;
+        res.pause();
+        setTimeout(
+          resume,
+          serverTimeout + offsetTimeout - (Date.now() - firstReceivedAt)
+        );
+        offsetTimeout = 0;
+      }
+    }, 1));
+    res.on('end', common.mustCall(() => {
+      server.close();
+    }));
+  }));
+}));