VPN Management

Overview

A virtual private network (VPN) is a dedicated network established on a public network. Unlike a traditional private network, a VPN does not require an end-to-end physical link between any two nodes. It is built over a network platform (for example, Internet) provided by a public network service provider. User data is transmitted over the logical link.

OpenHarmony provides the VPN Extension solution for enhanced VPN management. Currently, the VPN capabilities provided to third-party applications are primarily used for creating virtual NICs and configuring VPN routing information. The connection tunnel process and internal connection protocols need to be implemented by the applications themselves. The following guides you through on how to develop your own VPN client.

NOTE

• To maximize the application running efficiency, all APIs are called asynchronously in callback or promise mode. The following code examples use the promise mode. For details about the APIs, see API Reference.
• For details about the complete JavaScript APIs and sample code, see API Reference.
• To use related APIs, you must declare the ohos.permission.INTERNET permission.

VPN Extension Ability UI

With the VPN Extension APIs provided by OpenHarmony, you can build VPN services that support different protocols. OpenHarmony provides a UI for users to learn about VPN startup and connection.

• When the VPN application sets up a connection for the first time, the VPN connection authorization dialog box is displayed. The dialog box prompts users whether to trust the VPN application and accept the VPN connection request.
• If the VPN connection is successful, a VPN icon (a key) is displayed in the status bar to remind the user that the VPN is connected.

To facilitate the query and configuration, your VPN application needs to provide the following UIs:

• UI for manually starting and stopping the VPN connection.
• UI for displaying the connection status of the VPN application in the notification bar or providing network statistics (such as the connection duration and traffic) of the VPN connection. Touching the notification in notification bar should bring your VPN application to the foreground.

How to Develop

Creating a VPN Extension Ability

To enable your application to support the VPN functionality, you need to create an ExtensionAbilities instance inherited from VpnExtensionAbility.

// Assume that the VNP application is named MyVpnExtAbility. Define it in module.json5.
"extensionAbilities": [
// ···
  {
    "name": "MyVpnExtAbility",
    "srcEntry": "./ets/vpnability/VPNExtentionAbility.ets",
    "type": "vpn"
  }
],

NOTE

If the DevEco Studio tool displays a message indicating unrecognizable "type": "vpn", you need to manually add vpn to the type enums corresponding to extensionAbilities in the toolchains\modulecheck\module.json file of the SDK, clear the build cache, and restart DevEco Studio.

Next, you need to configure, start, and stop the VPN in the created VpnExtensionAbility.

• Establish a VPN tunnel. The following uses the UDP tunnel as an example. For details, see the UdpConnect() API in the napi_init demo project.
• Use VpnConnection.protect to enable protection for the UDP tunnel.
• Construct VPN Config parameters. For details, see VPN Config Parameters.
• Use VpnConnection.create to establish a VPN connection.
• Process data of the virtual network interface card (vNIC), such as reading or writing data.

Starting the VPN Extension Ability

To start a connection from the VPN application, you need to call startVpnExtensionAbility with the VpnExtensionAbility information specified. Make sure that bundleName is the same as that of the VPN application, and abilityName is the name of the VpnExtensionAbility you created. The sample code is as follows:

import { common, Want } from '@kit.AbilityKit';
import { vpnExtension } from '@kit.NetworkKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
// ···

const TITLE_FONT_SIZE = 35; // Title font size.
const BUTTON_FONT_SIZE = 25; // Button font size.
const BUTTON_MARGIN = 16;

let want: Want = {
  deviceId: '',
  bundleName: 'com.samples.vpncontrol_case',
  abilityName: 'MyVpnExtAbility',
};

@Entry
@Component
struct StartVpn {
  @State message: string = 'VPN';
// ···
  build() {
    Row() {
      Column() {
        // ···
        Text(this.message)
          .fontSize(TITLE_FONT_SIZE)
          .fontWeight(FontWeight.Bold)
        // ···
          .onClick(() => {
            hilog.info(0x0000, 'testTag', 'developTag', '%{public}s', 'vpn Client');
          })
        // ···
        Button($r('app.string.start_vpnExt'))
          .onClick(() => {
            // ···
              vpnExtension.startVpnExtensionAbility(want)
            // ···
          })
          .width('70%')
        // ···
          .fontSize(BUTTON_FONT_SIZE)
          .margin(BUTTON_MARGIN)
        // ···
      }.width('100%');
    }.height('100%');

  }
}

If your VPN app is not trusted by the user, the system displays a dialog box asking the user to authorize the VPN connection. After obtaining the authorization, the system automatically calls onCreate of the VpnExtensionAbility.

Currently, only one active VPN connection is supported. If the application calls startVpnExtensionAbility when a VPN connection is active, it will receive a system rejection error. In this case, you are advised to remind the user to disconnect the active VPN connection first.

Stopping the VPN Extension Ability

To stop a VPN connection, the VPN application needs to call stopVpnExtensionAbility with the target VpnExtensionAbility specified. The system verifies the permission of the caller. The caller of stopVpnExtensionAbility must have obtained the VPN connection authorization of the user and can only stop the VpnExtensionAbility it started. Therefore, make sure that the value of bundleName passed by the API is the same as that of the VPN application, and the value of abilityName is the same as that of the target VpnExtensionAbility.

The sample code is as follows:

import { common, Want } from '@kit.AbilityKit';
import { vpnExtension } from '@kit.NetworkKit';
import { hilog } from '@kit.PerformanceAnalysisKit';

const TITLE_FONT_SIZE = 35; // Title font size.
const BUTTON_FONT_SIZE = 25; // Button font size.
const BUTTON_MARGIN = 16;

let want: Want = {
  deviceId: '',
  bundleName: 'com.samples.vpncontrol_case',
  abilityName: 'MyVpnExtAbility',
};

@Entry
@Component
struct StopVpn {
  @State message: string = 'VPN';

  // ...
  build() {
    Row() {
      Column() {
        // ...
        Text(this.message)
          .fontSize(TITLE_FONT_SIZE)
          .fontWeight(FontWeight.Bold)
          .onClick(() => {
            hilog.info(0x0000, 'testTag', 'developTag', '%{public}s', 'vpn Client');
          })
        // ...
        Button('Start Extension').onClick(() => {
          vpnExtension.startVpnExtensionAbility(want);
        }).width('70%').fontSize(20).margin(16);
        Button($r('app.string.stop_vpnExt'))
          .onClick(() => {
            try {
              hilog.info(0x0000, 'testTag', 'btn end')
              vpnExtension.stopVpnExtensionAbility(want)
              // ...
            } catch (err) {
              // ...
              hilog.error(0x0000, 'testTag', 'developTag', 'stop vpnExt Fail %{public}s', JSON.stringify(err) ?? '');
            }

          })
          .width('70%')
          // ...
          .fontSize(BUTTON_FONT_SIZE)
          .margin(BUTTON_MARGIN)
      }.width('100%');
    }.height('100%');
  }
}

After the VPNExtensionAbility is stopped, call onDestroy to destroy the VPN connection and release related resources.

private context = this.getUIContext().getHostContext() as common.VpnExtensionContext;
private vpnConnection: vpnExtension.VpnConnection = vpnExtension.createVpnConnection(this.context);

Destroy() {
  hilog.info(0x0000, 'testTag', 'developTag', '%{public}s', 'vpn Destroy');
  // ...
  this.vpnConnection.destroy().then(() => {
    hilog.info(0x0000, 'testTag', 'developTag', '%{public}s', 'vpn Destroy Success');
    // ...
  }).catch((err: Error) => {
     hilog.error(0x0000, 'testTag', 'developTag', 'vpn Destroy Failed: %{public}s', JSON.stringify(err) ?? '');
    // ...
  })
}

Generating a VPN ID

When creating a VPN, generate a VPN ID as the unique identifier of the VPN.

The sample code is as follows:

import { vpnExtension, VpnExtensionAbility } from '@kit.NetworkKit';
// ...
export class VpnTest extends VpnExtensionAbility {
  public vpnId: string = '';
  // ...
  getVpnId() {
    // ...
      let vpnConnection = vpnExtension.createVpnConnection(this.context);
      vpnConnection?.generateVpnId().then((data) => {
        if (data) {
          this.vpnId = data;
        }
      });
    // ...
  }
};

Disconnecting from the VPN

To disconnect from the VPN, use the sample code below:

import { vpnExtension, VpnExtensionAbility } from '@kit.NetworkKit';
import { hilog } from '@kit.PerformanceAnalysisKit';
// ...
export class VpnTest extends VpnExtensionAbility {
  public vpnId: string = 'test_vpn_id';
  public vpnConnection: vpnExtension.VpnConnection | undefined;
  // ...
  destroy() {
    // ...
      this.vpnConnection = vpnExtension.createVpnConnection(this.context);
      hilog.info(0x0000, 'testTag', 'create success');
      this.vpnConnection?.destroy(this.vpnId);
      // ...
  }
};

Service Lifecycle Management

To ensure network connectivity, the system automatically stops the VPN connection when detecting that the VPN application is abnormal:

• The application process that calls startVpnExtensionAbility exits.
• The VPN service process is destroyed.

Description of VPN Config parameters

Example

import { vpnExtension } from '@kit.NetworkKit';
import { common } from '@kit.AbilityKit';
import { hilog } from '@kit.PerformanceAnalysisKit';

let vpnConfig: vpnExtension.VpnConfig = {
  // Configure the IP address of the vNIC.
  addresses: [{
    address: {
      address:'192.x.x.5',
      family:1
    },
    prefixLength:24
  }],
  // Configure route information.
  routes: [{
    // Set the name of the vNIC, which has a fixed value of vpn-tun.
    interface: 'vpn-tun',
    destination: {
      address: {
        address:'10.x.x.8',
        family:1,
        port:8080
      },
      prefixLength:24
    },
    gateway: {
      address:'10.x.x.5',
      family:1,
      port:8080
    },
    hasGateway: false,
    isDefaultRoute: false,
  }],
  // Configure the MTU.
  mtu: 1400,
  // Configure IP addresses of DNS serves.
  dnsAddresses: ['223.x.x.5', '223.x.x.6'],
  // List of trusted applications.
  trustedApplications: ['com.test.browser'],
  // List of blocked applications.
  blockedApplications: ['com.test.games'],
}

let context = this.getUIContext().getHostContext() as common.VpnExtensionContext;
let vpnConnection: vpnExtension.VpnConnection = vpnExtension.createVpnConnection(context);
// Create a VPN connection and apply the configuration.
vpnConnection.create(vpnConfig).then((data) => {
  hilog.info(0x0000, 'testTag', 'vpn create ' + JSON.stringify(data));
  // ...
})

VPN Demo

The OpenHarmony project provides a sample application named VPN, which showcases how to implement the VPN service.