Introduce Client Certificate configuration (#1183)

⚠️ This API is released as preview.
⚠️ This feature is NodeJS only. Browser should configure the client certificate in the system certificates. 

The ClientCertificate is a mechanism to support mutual TLS as a second factor for authentication. The driver's certificate will not be used to authenticate a user on the DBMS, but only to authenticate the driver as a trusted client to the DBMS. Another authentication mechanism is still required to authenticate the user.

The configuration is done by using the driver configuration, the property name is `clientCertificate` and this a object with the following properties:

* `certfile`: The path to client certificate file. This is can configured as list of paths.
* `keyfile`: The path to key file. This can also be configured as a list of paths, an object contain `path` and `password` or a list of objects contain `path` and `password`.
* `password` (optional): The client key password.

See [node documentation](https://nodejs.org/api/tls.html#tlscreatesecurecontextoptions) for understanding how password, certs and keys work together. 

Configuration example:

```javascript
import neo4j from 'neo4j-driver'

const driver = neo4j.driver('neo4j+s://myhost:7687', MY_CREDENTIALS, {
   clientCertificate: {
      certfile: '/path/to/cert/file.cert',
      keyfile: '/path/to/cert/file.pem',
      password: 'the_key_password' // optional
   }
})

// then use your driver as usual. 
```

### Client Certificate Provider and Certificate Rotation

In case of the certificate needs to be changed, the driver offers an api for change client certificates without creating a new driver instance. The change is done by inform an `ClientCertificateProvider` instead of a `ClientCertificate` in the driver configuration. 

`ClientCertificateProvider` is a public interface which can be implemented by user. However, the driver offers an implementation of this interface for working with certificate rotation scenarios. 

```javascript
import neo4j from 'neo4j-driver'

const initialClientCertificate: {
  certfile: '/path/to/cert/file.cert',
  keyfile: '/path/to/cert/file.pem',
  password: 'the_key_password' // optional
}

const clientCertificateProvider = neo4j.clientCertificateProviders.rotating({
    initialCertificate: initialClientCertificate
})

const driver = neo4j.driver('neo4j+s://myhost:7687', MY_CREDENTIALS, {
   clientCertificate: clientCertificateProvider
})


// use the driver as usual

// then you have new certificate which will replace the old one
clientCertificateProvider.updateCertificate({
  certfile: '/path/to/cert/new_file.cert',
  keyfile: '/path/to/cert/new_file.pem',
  password: 'the_new_key_password' // optional
})

// New connections will be created using the new certificate.
// however, older connections will not be closed if they still working.
```

⚠️ This feature is NodeJS only. Browser should configure the client certificate in the system certificates. 
⚠️ This API is released as preview.

Author: bigmontz

packages/bolt-connection/src/channel/browser/browser-client-certificates-loader.js

@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [https://neo4j.com]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+export default {
+  async load (clientCertificate) {
+    return clientCertificate
+  }
+}

packages/bolt-connection/src/channel/browser/index.js

@@ -17,7 +17,7 @@
 
 import WebSocketChannel from './browser-channel'
 import BrowserHosNameResolver from './browser-host-name-resolver'
-
+import BrowserClientCertificatesLoader from './browser-client-certificates-loader'
 /*
 
 This module exports a set of components to be used in browser environment.
@@ -30,3 +30,4 @@ NOTE: exports in this module should have exactly the same names/structure as exp
  */
 export const Channel = WebSocketChannel
 export const HostNameResolver = BrowserHosNameResolver
+export const ClientCertificatesLoader = BrowserClientCertificatesLoader

packages/bolt-connection/src/channel/channel-config.js

@@ -46,15 +46,17 @@ export default class ChannelConfig {
    * @param {ServerAddress} address the address for the channel to connect to.
    * @param {Object} driverConfig the driver config provided by the user when driver is created.
    * @param {string} connectionErrorCode the default error code to use on connection errors.
+   * @param {object} clientCertificate the client certificate
    */
-  constructor (address, driverConfig, connectionErrorCode) {
+  constructor (address, driverConfig, connectionErrorCode, clientCertificate) {
     this.address = address
     this.encrypted = extractEncrypted(driverConfig)
     this.trust = extractTrust(driverConfig)
     this.trustedCertificates = extractTrustedCertificates(driverConfig)
     this.knownHostsPath = extractKnownHostsPath(driverConfig)
     this.connectionErrorCode = connectionErrorCode || SERVICE_UNAVAILABLE
     this.connectionTimeout = driverConfig.connectionTimeout
+    this.clientCertificate = clientCertificate
   }
 }
 

packages/bolt-connection/src/channel/deno/deno-channel.js

@@ -239,6 +239,8 @@ const TrustStrategy = {
       );
     }
 
+    assertNotClientCertificates(config)
+
     const caCerts = await Promise.all(
       config.trustedCertificates.map(f => Deno.readTextFile(f))
     )
@@ -250,6 +252,8 @@ const TrustStrategy = {
     })
   },
   TRUST_SYSTEM_CA_SIGNED_CERTIFICATES: function (config) {
+    assertNotClientCertificates(config)
+    
     return Deno.connectTls({ 
       hostname: config.address.resolvedHost(), 
       port: config.address.port()
@@ -265,6 +269,13 @@ const TrustStrategy = {
   }
 }
 
+async function assertNotClientCertificates (config) {
+  if (config.clientCertificate != null) {
+    throw newError('clientCertificates are not supported in DenoJS since the API does not ' +
+      'support its configuration. See, https://deno.land/api@v1.29.0?s=Deno.ConnectTlsOptions.')
+  } 
+}
+
 async function _connect (config) {
   if (!isEncrypted(config)) {
     return Deno.connect({ 

packages/bolt-connection/src/channel/deno/deno-client-certificates-loader.js

@@ -0,0 +1,21 @@
+/**
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [https://neo4j.com]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+export default {
+  async load (clientCertificate) {
+    return clientCertificate
+  }
+}

packages/bolt-connection/src/channel/deno/index.js

@@ -17,7 +17,7 @@
 
 import DenoChannel from './deno-channel'
 import DenoHostNameResolver from './deno-host-name-resolver'
-
+import DenoClientCertificatesLoader from './deno-client-certificates-loader'
 /*
 
  This module exports a set of components to be used in deno environment.
@@ -30,3 +30,4 @@ import DenoHostNameResolver from './deno-host-name-resolver'
   */
 export const Channel = DenoChannel
 export const HostNameResolver = DenoHostNameResolver
+export const ClientCertificatesLoader = DenoClientCertificatesLoader

packages/bolt-connection/src/channel/node/index.js

@@ -17,7 +17,7 @@
 
 import NodeChannel from './node-channel'
 import NodeHostNameResolver from './node-host-name-resolver'
-
+import NodeClientCertificatesLoader from './node-client-certificates-loader'
 /*
 
 This module exports a set of components to be used in NodeJS environment.
@@ -31,3 +31,4 @@ NOTE: exports in this module should have exactly the same names/structure as exp
 
 export const Channel = NodeChannel
 export const HostNameResolver = NodeHostNameResolver
+export const ClientCertificatesLoader = NodeClientCertificatesLoader

packages/bolt-connection/src/channel/node/node-channel.js

@@ -49,7 +49,8 @@ const TrustStrategy = {
 
     const tlsOpts = newTlsOptions(
       config.address.host(),
-      config.trustedCertificates.map(f => fs.readFileSync(f))
+      config.trustedCertificates.map(f => fs.readFileSync(f)),
+      config.clientCertificate
     )
     const socket = tls.connect(
       config.address.port(),
@@ -79,7 +80,11 @@ const TrustStrategy = {
     return configureSocket(socket)
   },
   TRUST_SYSTEM_CA_SIGNED_CERTIFICATES: function (config, onSuccess, onFailure) {
-    const tlsOpts = newTlsOptions(config.address.host())
+    const tlsOpts = newTlsOptions(
+      config.address.host(),
+      undefined,
+      config.clientCertificate
+    )
     const socket = tls.connect(
       config.address.port(),
       config.address.resolvedHost(),
@@ -109,7 +114,11 @@ const TrustStrategy = {
     return configureSocket(socket)
   },
   TRUST_ALL_CERTIFICATES: function (config, onSuccess, onFailure) {
-    const tlsOpts = newTlsOptions(config.address.host())
+    const tlsOpts = newTlsOptions(
+      config.address.host(),
+      undefined,
+      config.clientCertificate
+    )
     const socket = tls.connect(
       config.address.port(),
       config.address.resolvedHost(),
@@ -198,13 +207,17 @@ function trustStrategyName (config) {
  * Create a new configuration options object for the {@code tls.connect()} call.
  * @param {string} hostname the target hostname.
  * @param {string|undefined} ca an optional CA.
+ * @param {string|undefined} cert an optional client cert.
+ * @param {string|undefined} key an optional client cert key.
+ * @param {string|undefined} passphrase an optional client cert passphrase
  * @return {Object} a new options object.
  */
-function newTlsOptions (hostname, ca = undefined) {
+function newTlsOptions (hostname, ca = undefined, clientCertificate = undefined) {
   return {
     rejectUnauthorized: false, // we manually check for this in the connect callback, to give a more helpful error to the user
     servername: hostname, // server name for the SNI (Server Name Indication) TLS extension
-    ca // optional CA useful for TRUST_CUSTOM_CA_SIGNED_CERTIFICATES trust mode
+    ca, // optional CA useful for TRUST_CUSTOM_CA_SIGNED_CERTIFICATES trust mode,
+    ...clientCertificate
   }
 }
 

packages/bolt-connection/src/channel/node/node-client-certificates-loader.js

@@ -0,0 +1,65 @@
+/**
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [https://neo4j.com]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import fs from 'fs'
+
+function readFile (file) {
+  return new Promise((resolve, reject) => fs.readFile(file, (err, data) => {
+    if (err) {
+      return reject(err)
+    }
+    return resolve(data)
+  }))
+}
+
+function loadCert (fileOrFiles) {
+  if (Array.isArray(fileOrFiles)) {
+    return Promise.all(fileOrFiles.map(loadCert))
+  }
+  return readFile(fileOrFiles)
+}
+
+function loadKey (fileOrFiles) {
+  if (Array.isArray(fileOrFiles)) {
+    return Promise.all(fileOrFiles.map(loadKey))
+  }
+
+  if (typeof fileOrFiles === 'string') {
+    return readFile(fileOrFiles)
+  }
+
+  return readFile(fileOrFiles.path)
+    .then(pem => ({
+      pem,
+      passphrase: fileOrFiles.password
+    }))
+}
+
+export default {
+  async load (clientCertificate) {
+    const certPromise = loadCert(clientCertificate.certfile)
+    const keyPromise = loadKey(clientCertificate.keyfile)
+
+    const [cert, key] = await Promise.all([certPromise, keyPromise])
+
+    return {
+      cert,
+      key,
+      passphrase: clientCertificate.password
+    }
+  }
+}

packages/bolt-connection/src/connection-provider/client-certificate-holder.js

@@ -0,0 +1,43 @@
+/**
+ * Copyright (c) "Neo4j"
+ * Neo4j Sweden AB [https://neo4j.com]
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import { ClientCertificatesLoader } from '../channel'
+
+export default class ClientCertificateHolder {
+  constructor ({ clientCertificateProvider, loader }) {
+    this._clientCertificateProvider = clientCertificateProvider
+    this._loader = loader || ClientCertificatesLoader
+    this._clientCertificate = null
+  }
+
+  async getClientCertificate () {
+    if (this._clientCertificateProvider != null &&
+      (this._clientCertificate == null || await this._clientCertificateProvider.hasUpdate())) {
+      this._clientCertificate = Promise.resolve(this._clientCertificateProvider.getClientCertificate())
+        .then(this._loader.load)
+        .then(clientCertificate => {
+          this._clientCertificate = clientCertificate
+          return this._clientCertificate
+        })
+        .catch(error => {
+          this._clientCertificate = null
+          throw error
+        })
+    }
+
+    return this._clientCertificate
+  }
+}