net: fix timeout with null handle

This commit handles the case where _onTimeout is called with a
null handle.

Refs: nodejs/node#15791
Fixes: nodejs/node#16484
PR-URL: nodejs/node#16489
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>

lib/net.js

@@ -397,13 +397,15 @@ 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;
+  if (this._handle) {
+    // `.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');

test/parallel/test-net-timeout-no-handle.js

@@ -0,0 +1,17 @@
+'use strict';
+
+const common = require('../common');
+const net = require('net');
+const assert = require('assert');
+
+const socket = new net.Socket();
+socket.setTimeout(common.platformTimeout(50));
+
+socket.on('timeout', common.mustCall(() => {
+  assert.strictEqual(socket._handle, null);
+}));
+
+socket.on('connect', common.mustNotCall());
+
+// since the timeout is unrefed, the code will exit without this
+setTimeout(() => {}, common.platformTimeout(200));