From 10815c4eff5361a18bafb718287c947e7b5f6e1e Mon Sep 17 00:00:00 2001
From: Robert Nagy <ronagy@icloud.com>
Date: Thu, 30 Jul 2020 16:58:08 +0200
Subject: [PATCH] http: provide keep-alive timeout response header

In http 1.1 persistent connection protocol there is a
timing race where the client sends the request and then
the server kills the connection (due to inactivity)
before receiving the client's request.

By providing a keep-alive header it is possible to provide
the client a hint of when idle timeout would occur and
avoid the race.

Fixes: https://github.com/nodejs/node/issues/34560

PR-URL: https://github.com/nodejs/node/pull/34561
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Pranshu Srivastava <rexagod@gmail.com>
---
 lib/_http_outgoing.js                         |  7 +++++
 lib/_http_server.js                           |  1 +
 test/parallel/test-http-keep-alive-timeout.js | 28 +++++++++++++++++++
 3 files changed, 36 insertions(+)
 create mode 100644 test/parallel/test-http-keep-alive-timeout.js

diff --git a/lib/_http_outgoing.js b/lib/_http_outgoing.js
index 442369581d3779..8de389e1f09dd4 100644
--- a/lib/_http_outgoing.js
+++ b/lib/_http_outgoing.js
@@ -28,6 +28,7 @@ const {
   ObjectKeys,
   ObjectPrototypeHasOwnProperty,
   ObjectSetPrototypeOf,
+  MathFloor,
   Symbol,
 } = primordials;
 
@@ -117,6 +118,8 @@ function OutgoingMessage() {
   this._header = null;
   this[kOutHeaders] = null;
 
+  this._keepAliveTimeout = 0;
+
   this._onPendingData = noopPendingOutput;
 }
 ObjectSetPrototypeOf(OutgoingMessage.prototype, Stream.prototype);
@@ -402,6 +405,10 @@ function _storeHeader(firstLine, headers) {
         (state.contLen || this.useChunkedEncodingByDefault || this.agent);
     if (shouldSendKeepAlive) {
       header += 'Connection: keep-alive\r\n';
+      if (this._keepAliveTimeout) {
+        const timeoutSeconds = MathFloor(this._keepAliveTimeout) / 1000;
+        header += `Keep-Alive: timeout=${timeoutSeconds}\r\n`;
+      }
     } else {
       this._last = true;
       header += 'Connection: close\r\n';
diff --git a/lib/_http_server.js b/lib/_http_server.js
index c707ca3f9949b1..4d1f8e4fbd7077 100644
--- a/lib/_http_server.js
+++ b/lib/_http_server.js
@@ -740,6 +740,7 @@ function parserOnIncoming(server, socket, state, req, keepAlive) {
   }
 
   const res = new server[kServerResponse](req);
+  res._keepAliveTimeout = server.keepAliveTimeout;
   res._onPendingData = updateOutgoingData.bind(undefined, socket, state);
 
   res.shouldKeepAlive = keepAlive;
diff --git a/test/parallel/test-http-keep-alive-timeout.js b/test/parallel/test-http-keep-alive-timeout.js
new file mode 100644
index 00000000000000..fccb267b8e9ee2
--- /dev/null
+++ b/test/parallel/test-http-keep-alive-timeout.js
@@ -0,0 +1,28 @@
+'use strict';
+
+const common = require('../common');
+const http = require('http');
+const assert = require('assert');
+
+const server = http.createServer(common.mustCall((req, res) => {
+  const body = 'hello world\n';
+
+  res.writeHead(200, { 'Content-Length': body.length });
+  res.write(body);
+  res.end();
+}));
+server.keepAliveTimeout = 12000;
+
+const agent = new http.Agent({ maxSockets: 1, keepAlive: true });
+
+server.listen(0, common.mustCall(function() {
+  http.get({
+    path: '/', port: this.address().port, agent: agent
+  }, common.mustCall((response) => {
+    response.resume();
+    assert.strictEqual(
+      response.headers['keep-alive'], 'timeout=12');
+    server.close();
+    agent.destroy();
+  }));
+}));