tls: support changing credentials dynamically

This commit adds a setSecureContext() method to TLS servers. In
order to maintain backwards compatibility, the method takes the
options needed to create a new SecureContext, rather than an
instance of SecureContext.

Fixes: https://github.com/nodejs/node/issues/4464
Refs: https://github.com/nodejs/node/issues/10349
Refs: https://github.com/nodejs/help/issues/603
Refs: https://github.com/nodejs/node/issues/15115
PR-URL: https://github.com/nodejs/node/pull/23644
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

3 files changed, 214 insertions, 24 deletions

diff --git a/doc/api/tls.md b/doc/api/tls.md
index 4f3430854e..f9a313f914 100644
--- a/doc/api/tls.md
+++ b/doc/api/tls.md
@@ -411,6 +411,18 @@ encryption/decryption of the [TLS Session Tickets][].
 Starts the server listening for encrypted connections.
 This method is identical to [`server.listen()`][] from [`net.Server`][].
 
+### server.setSecureContext(options)
+<!-- YAML
+added: REPLACEME
+-->
+
+* `options` {Object} An object containing any of the possible properties from
+  the [`tls.createSecureContext()`][] `options` arguments (e.g. `key`, `cert`,
+  `ca`, etc).
+
+The `server.setSecureContext()` method replaces the secure context of an
+existing server. Existing connections to the server are not interrupted.
+
 ### server.setTicketKeys(keys)
 <!-- YAML
 added: v3.0.0
diff --git a/lib/_tls_wrap.js b/lib/_tls_wrap.js
index b28e3b62b7..aa8b66b715 100644
--- a/lib/_tls_wrap.js
+++ b/lib/_tls_wrap.js
@@ -833,22 +833,11 @@ function Server(options, listener) {
   // Handle option defaults:
   this.setOptions(options);
 
-  this._sharedCreds = tls.createSecureContext({
-    pfx: this.pfx,
-    key: this.key,
-    passphrase: this.passphrase,
-    cert: this.cert,
-    clientCertEngine: this.clientCertEngine,
-    ca: this.ca,
-    ciphers: this.ciphers,
-    ecdhCurve: this.ecdhCurve,
-    dhparam: this.dhparam,
-    secureProtocol: this.secureProtocol,
-    secureOptions: this.secureOptions,
-    honorCipherOrder: this.honorCipherOrder,
-    crl: this.crl,
-    sessionIdContext: this.sessionIdContext
-  });
+  // setSecureContext() overlaps with setOptions() quite a bit. setOptions()
+  // is an undocumented API that was probably never intended to be exposed
+  // publicly. Unfortunately, it would be a breaking change to just remove it,
+  // and there is at least one test that depends on it.
+  this.setSecureContext(options);
 
   this[kHandshakeTimeout] = options.handshakeTimeout || (120 * 1000);
   this[kSNICallback] = options.SNICallback;
@@ -863,14 +852,6 @@ function Server(options, listener) {
       'options.SNICallback', 'function', options.SNICallback);
   }
 
-  if (this.sessionTimeout) {
-    this._sharedCreds.context.setSessionTimeout(this.sessionTimeout);
-  }
-
-  if (this.ticketKeys) {
-    this._sharedCreds.context.setTicketKeys(this.ticketKeys);
-  }
-
   // constructor call
   net.Server.call(this, tlsConnectionListener);
 
@@ -886,6 +867,115 @@ exports.createServer = function createServer(options, listener) {
 };
 
 
+Server.prototype.setSecureContext = function(options) {
+  if (options === null || typeof options !== 'object')
+    throw new ERR_INVALID_ARG_TYPE('options', 'Object', options);
+
+  if (options.pfx)
+    this.pfx = options.pfx;
+  else
+    this.pfx = undefined;
+
+  if (options.key)
+    this.key = options.key;
+  else
+    this.key = undefined;
+
+  if (options.passphrase)
+    this.passphrase = options.passphrase;
+  else
+    this.passphrase = undefined;
+
+  if (options.cert)
+    this.cert = options.cert;
+  else
+    this.cert = undefined;
+
+  if (options.clientCertEngine)
+    this.clientCertEngine = options.clientCertEngine;
+  else
+    this.clientCertEngine = undefined;
+
+  if (options.ca)
+    this.ca = options.ca;
+  else
+    this.ca = undefined;
+
+  if (options.secureProtocol)
+    this.secureProtocol = options.secureProtocol;
+  else
+    this.secureProtocol = undefined;
+
+  if (options.crl)
+    this.crl = options.crl;
+  else
+    this.crl = undefined;
+
+  if (options.ciphers)
+    this.ciphers = options.ciphers;
+  else
+    this.ciphers = undefined;
+
+  if (options.ecdhCurve !== undefined)
+    this.ecdhCurve = options.ecdhCurve;
+  else
+    this.ecdhCurve = undefined;
+
+  if (options.dhparam)
+    this.dhparam = options.dhparam;
+  else
+    this.dhparam = undefined;
+
+  if (options.honorCipherOrder !== undefined)
+    this.honorCipherOrder = !!options.honorCipherOrder;
+  else
+    this.honorCipherOrder = true;
+
+  const secureOptions = options.secureOptions || 0;
+
+  if (secureOptions)
+    this.secureOptions = secureOptions;
+  else
+    this.secureOptions = undefined;
+
+  if (options.sessionIdContext) {
+    this.sessionIdContext = options.sessionIdContext;
+  } else {
+    this.sessionIdContext = crypto.createHash('sha1')
+                                  .update(process.argv.join(' '))
+                                  .digest('hex')
+                                  .slice(0, 32);
+  }
+
+  this._sharedCreds = tls.createSecureContext({
+    pfx: this.pfx,
+    key: this.key,
+    passphrase: this.passphrase,
+    cert: this.cert,
+    clientCertEngine: this.clientCertEngine,
+    ca: this.ca,
+    ciphers: this.ciphers,
+    ecdhCurve: this.ecdhCurve,
+    dhparam: this.dhparam,
+    secureProtocol: this.secureProtocol,
+    secureOptions: this.secureOptions,
+    honorCipherOrder: this.honorCipherOrder,
+    crl: this.crl,
+    sessionIdContext: this.sessionIdContext
+  });
+
+  if (this.sessionTimeout)
+    this._sharedCreds.context.setSessionTimeout(this.sessionTimeout);
+
+  if (options.ticketKeys) {
+    this.ticketKeys = options.ticketKeys;
+    this.setTicketKeys(this.ticketKeys);
+  } else {
+    this.setTicketKeys(this.getTicketKeys());
+  }
+};
+
+
 Server.prototype._getServerData = function() {
   return {
     ticketKeys: this.getTicketKeys().toString('hex')
diff --git a/test/parallel/test-tls-set-secure-context.js b/test/parallel/test-tls-set-secure-context.js
new file mode 100644
index 0000000000..51ab3af10b
--- /dev/null
+++ b/test/parallel/test-tls-set-secure-context.js
@@ -0,0 +1,88 @@
+'use strict';
+const common = require('../common');
+
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+
+const assert = require('assert');
+const https = require('https');
+const fixtures = require('../common/fixtures');
+const credentialOptions = [
+  {
+    key: fixtures.readKey('agent1-key.pem'),
+    cert: fixtures.readKey('agent1-cert.pem'),
+    ca: fixtures.readKey('ca1-cert.pem')
+  },
+  {
+    key: fixtures.readKey('agent2-key.pem'),
+    cert: fixtures.readKey('agent2-cert.pem'),
+    ca: fixtures.readKey('ca2-cert.pem')
+  }
+];
+let requestsCount = 0;
+let firstResponse;
+
+const server = https.createServer(credentialOptions[0], (req, res) => {
+  requestsCount++;
+
+  if (requestsCount === 1) {
+    firstResponse = res;
+    firstResponse.write('multi-');
+    return;
+  } else if (requestsCount === 3) {
+    firstResponse.write('success-');
+  }
+
+  res.end('success');
+});
+
+server.listen(0, common.mustCall(async () => {
+  const { port } = server.address();
+  const firstRequest = makeRequest(port);
+
+  assert.strictEqual(await makeRequest(port), 'success');
+
+  server.setSecureContext(credentialOptions[1]);
+  firstResponse.write('request-');
+  await assert.rejects(async () => {
+    await makeRequest(port);
+  }, /^Error: self signed certificate$/);
+
+  server.setSecureContext(credentialOptions[0]);
+  assert.strictEqual(await makeRequest(port), 'success');
+
+  server.setSecureContext(credentialOptions[1]);
+  firstResponse.end('fun!');
+  await assert.rejects(async () => {
+    await makeRequest(port);
+  }, /^Error: self signed certificate$/);
+
+  assert.strictEqual(await firstRequest, 'multi-request-success-fun!');
+  server.close();
+}));
+
+function makeRequest(port) {
+  return new Promise((resolve, reject) => {
+    const options = {
+      rejectUnauthorized: true,
+      ca: credentialOptions[0].ca,
+      servername: 'agent1'
+    };
+
+    https.get(`https://localhost:${port}`, options, (res) => {
+      let response = '';
+
+      res.setEncoding('utf8');
+
+      res.on('data', (chunk) => {
+        response += chunk;
+      });
+
+      res.on('end', common.mustCall(() => {
+        resolve(response);
+      }));
+    }).on('error', (err) => {
+      reject(err);
+    });
+  });
+}