tls: add tlsSocket.disableRenegotiation()

Allows TLS renegotiation to be disabled per `TLSSocket` instance.
Per HTTP/2, TLS renegotiation is forbidden after the initial
connection prefix is exchanged.

PR-URL: #14239
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

doc/api/tls.md

@@ -552,6 +552,14 @@ added: v0.11.4
 Returns `true` if the peer certificate was signed by one of the CAs specified
 when creating the `tls.TLSSocket` instance, otherwise `false`.
 
+### tlsSocket.disableRenegotiation()
+<!-- YAML
+added: REPLACEME
+-->
+
+Disables TLS renegotiation for this `TLSSocket` instance. Once called, attempts
+to renegotiate will trigger an `'error'` event on the `TLSSocket`.
+
 ### tlsSocket.encrypted
 <!-- YAML
 added: v0.11.4

lib/_tls_wrap.js

@@ -37,6 +37,7 @@ const tls_wrap = process.binding('tls_wrap');
 const TCP = process.binding('tcp_wrap').TCP;
 const Pipe = process.binding('pipe_wrap').Pipe;
 const errors = require('internal/errors');
+const kDisableRenegotiation = Symbol('disable-renegotiation');
 
 function onhandshakestart() {
   debug('onhandshakestart');
@@ -64,6 +65,11 @@ function onhandshakestart() {
       self._emitTLSError(err);
     });
   }
+
+  if (this[kDisableRenegotiation] && ssl.handshakes > 0) {
+    const err = new Error('TLS session renegotiation disabled for this socket');
+    self._emitTLSError(err);
+  }
 }
 
 
@@ -358,6 +364,10 @@ tls_wrap.TLSWrap.prototype.close = function close(cb) {
   return this._parent.close(done);
 };
 
+TLSSocket.prototype.disableRenegotiation = function disableRenegotiation() {
+  this[kDisableRenegotiation] = true;
+};
+
 TLSSocket.prototype._wrapHandle = function(wrap) {
   var res;
   var handle;

test/parallel/test-tls-disable-renegotiation.js

@@ -0,0 +1,67 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const fs = require('fs');
+
+// Tests that calling disableRenegotiation on a TLSSocket stops renegotiation.
+
+if (!common.hasCrypto) {
+  common.skip('missing crypto');
+  return;
+}
+const tls = require('tls');
+
+const options = {
+  key: fs.readFileSync(`${common.fixturesDir}/keys/agent1-key.pem`),
+  cert: fs.readFileSync(`${common.fixturesDir}/keys/agent1-cert.pem`)
+};
+
+const server = tls.Server(options, common.mustCall((socket) => {
+  socket.on('error', common.mustCall((err) => {
+    assert.strictEqual(
+      err.message,
+      'TLS session renegotiation disabled for this socket');
+    socket.destroy();
+    server.close();
+  }));
+  // Disable renegotiation after the first chunk of data received.
+  // Demonstrates that renegotiation works successfully up until
+  // disableRenegotiation is called.
+  socket.on('data', common.mustCall((chunk) => {
+    socket.write(chunk);
+    socket.disableRenegotiation();
+  }));
+  socket.on('secure', common.mustCall(() => {
+    assert(socket._handle.handshakes < 2,
+           `Too many handshakes [${socket._handle.handshakes}]`);
+  }));
+}));
+
+
+server.listen(0, common.mustCall(() => {
+  const port = server.address().port;
+  const client =
+    tls.connect({rejectUnauthorized: false, port: port}, common.mustCall(() => {
+      client.write('');
+      // Negotiation is still permitted for this first
+      // attempt. This should succeed.
+      client.renegotiate(
+        {rejectUnauthorized: false},
+        common.mustCall(() => {
+          // Once renegotiation completes, we write some
+          // data to the socket, which triggers the on
+          // data event on the server. After that data
+          // is received, disableRenegotiation is called.
+          client.write('data', common.mustCall(() => {
+            client.write('');
+            // This second renegotiation attempt should fail
+            // and the callback should never be invoked. The
+            // server will simply drop the connection after
+            // emitting the error.
+            client.renegotiate(
+              {rejectUnauthorized: false},
+              common.mustNotCall());
+          }));
+        }));
+    }));
+}));