http: handle cases where socket.server is null

Fixes a regression that caused an error to be thrown when trying to
emit the 'timeout' event on the server referenced by `socket.server`.

Fixes: #13435
Refs: #11926
PR-URL: #13578
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/_http_server.js

@@ -294,6 +294,11 @@ function connectionListener(socket) {
 
   httpSocketSetup(socket);
 
+  // Ensure that the server property of the socket is correctly set.
+  // See https://github.com/nodejs/node/issues/13435
+  if (socket.server === null)
+    socket.server = this;
+
   // If the user has added a listener to the server,
   // request, or response, then it's their responsibility.
   // otherwise, destroy on timeout by default

test/parallel/test-cluster-send-socket-to-worker-http-server.js

@@ -0,0 +1,39 @@
+'use strict';
+
+// Regression test for https://github.com/nodejs/node/issues/13435
+// Tests that `socket.server` is correctly set when a socket is sent to a worker
+// and the `'connection'` event is emitted manually on an HTTP server.
+
+const common = require('../common');
+const assert = require('assert');
+const cluster = require('cluster');
+const http = require('http');
+const net = require('net');
+
+if (cluster.isMaster) {
+  const worker = cluster.fork();
+  const server = net.createServer(common.mustCall((socket) => {
+    worker.send('socket', socket);
+  }));
+
+  worker.on('exit', common.mustCall((code) => {
+    assert.strictEqual(code, 0);
+    server.close();
+  }));
+
+  server.listen(0, common.mustCall(() => {
+    net.createConnection(server.address().port);
+  }));
+} else {
+  const server = http.createServer();
+
+  server.on('connection', common.mustCall((socket) => {
+    assert.strictEqual(socket.server, server);
+    socket.destroy();
+    cluster.worker.disconnect();
+  }));
+
+  process.on('message', common.mustCall((message, socket) => {
+    server.emit('connection', socket);
+  }));
+}