tls: reduce TLS 'close' event listener warnings

Without this, some heavy usage of TLS sockets can result in
MaxListenersExceededWarning firing, from the 'this.on('close', ...)'
line here.

These appear to come from reinitializeHandle, which calls _wrapHandle
repeatedly on the same socket instance.

PR-URL: https://github.com/nodejs/node/pull/50136
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

lib/_tls_wrap.js

@@ -713,7 +713,12 @@ TLSSocket.prototype._wrapHandle = function(wrap, handle, wrapHasActiveWriteFromP
   this[kRes] = res;
   defineHandleReading(this, handle);
 
-  this.on('close', onSocketCloseDestroySSL);
+  // Guard against adding multiple listeners, as this method may be called
+  // repeatedly on the same socket by reinitializeHandle
+  if (this.listenerCount('close', onSocketCloseDestroySSL) === 0) {
+    this.on('close', onSocketCloseDestroySSL);
+  }
+
   if (wrap) {
     wrap.on('close', () => this.destroy());
   }

test/parallel/test-tls-reinitialize-listeners.js

@@ -0,0 +1,42 @@
+// Flags: --expose-internals
+'use strict';
+
+const common = require('../common');
+
+if (!common.hasCrypto) {
+  common.skip('missing crypto');
+}
+
+const events = require('events');
+const fixtures = require('../common/fixtures');
+const tls = require('tls');
+const { kReinitializeHandle } = require('internal/net');
+
+// Test that repeated calls to kReinitializeHandle() do not result in repeatedly
+// adding new listeners on the socket (i.e. no MaxListenersExceededWarnings)
+
+process.on('warning', common.mustNotCall());
+
+const server = tls.createServer({
+  key: fixtures.readKey('agent1-key.pem'),
+  cert: fixtures.readKey('agent1-cert.pem')
+});
+
+server.listen(0, common.mustCall(function() {
+  const socket = tls.connect({
+    port: this.address().port,
+    rejectUnauthorized: false
+  });
+
+  socket.on('secureConnect', common.mustCall(function() {
+    for (let i = 0; i < events.defaultMaxListeners + 1; i++) {
+      socket[kReinitializeHandle]();
+    }
+
+    socket.destroy();
+  }));
+
+  socket.on('close', function() {
+    server.close();
+  });
+}));