1# VPN Extension Ability Development 2 3## Introduction 4 5A 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. 6 7OpenHarmony provides the VPN Extension solution for enhanced VPN management. The following guides you through on how to develop your own VPN client. 8 9> **NOTE** 10> 11> 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](../reference/apis-network-kit/js-apis-net-vpnExtension.md). 12 13## VPN Extension Ability UI 14 15With 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. 16 17- 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. 18- 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. 19 20To facilitate the query and configuration, your VPN application needs to provide the following UIs: 21 22- UI for manually starting and stopping the VPN connection. 23- 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. 24 25## Available APIs 26 27For details about the complete JavaScript APIs and sample code, see [API Reference](../reference/apis-network-kit/js-apis-net-vpnExtension.md). 28 29## Creating a VPN Extension Ability 30 31To enable your application to support the VPN functionality, you need to create an **ExtensionAbilities** instance inherited from **VpnExtensionAbility**. 32 33```ts 34// Assume that the VNP application is named MyVpnExtAbility. Define it in module.json5. 35"extensionAbilities": [ 36 { 37 "name": "MyVpnExtAbility", 38 "description": "vpnservice", 39 "type": "vpn", 40 "srcEntry": "./ets/serviceextability/MyVpnExtAbility.ts" 41 } 42] 43``` 44 45> **NOTE** 46> 47> 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 and clear the build cache. 48 49Next, you need to configure, start, and stop the VPN in the created **VpnExtensionAbility**. 50 51- Create a VPN tunnel. The TCP tunnel is used as an example. For details, see **TcpConnect()** in [vpn_client](https://gitee.com/openharmony/applications_app_samples/blob/master/code/BasicFeature/Connectivity/VPN/entry/src/main/cpp/vpn_client.cpp) demo project. 52- Use [VpnConnection.protect](../reference/apis-network-kit/js-apis-net-vpnExtension.md#protect) to enable protection for the TCP tunnel. 53- Construct VPN Config parameters. For details, see [VPN Config Parameters](#description-of-vpn-config-parameters). 54- Use [VpnConnection.create](../reference/apis-network-kit/js-apis-net-vpnExtension.md#create) to establish a VPN connection. 55- Process data of the virtual network interface card (vNIC), such as reading or writing data. 56 57 58## Starting the VPN Extension Ability 59 60To 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: 61 62```ts 63import { common, Want } from '@kit.AbilityKit'; 64import { vpnExtension } from '@kit.NetworkKit'; 65 66let context = getContext(this) as common.VpnExtensionContext; 67let want: Want = { 68 deviceId: "", 69 bundleName: "com.example.myvpndemo", 70 abilityName: "MyVpnExtAbility", 71}; 72 73@Entry 74@Component 75struct Index { 76 @State message: string = 'Hello World'; 77 78 build() { 79 Row() { 80 Column() { 81 Text(this.message) 82 .fontSize(50) 83 .fontWeight(FontWeight.Bold).onClick(() => { 84 console.info("btn click") }) 85 Button('Start Extension').onClick(() => { 86 vpnExtension.startVpnExtensionAbility(want); 87 }).width('70%').fontSize(45).margin(16) 88 }.width('100%') 89 }.height('100%') 90 } 91} 92``` 93 94If 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](../reference/apis-network-kit/js-apis-VpnExtensionAbility.md#vpnextensionabilityoncreate) of the **VpnExtensionAbility**. 95 96Currently, 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. 97 98 99 100## Stopping the VPN Extension Ability 101 102To 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**. 103 104The sample code is as follows: 105 106```ts 107import { common, Want } from '@kit.AbilityKit'; 108import { vpnExtension } from '@kit.NetworkKit'; 109 110let context = getContext(this) as common.VpnExtensionContext; 111let want: Want = { 112 deviceId: "", 113 bundleName: "com.example.myvpndemo", 114 abilityName: "MyVpnExtAbility", 115}; 116 117@Entry 118@Component 119struct Index { 120 @State message: string = 'Hello World'; 121 122 build() { 123 Row() { 124 Column() { 125 Text(this.message) 126 .fontSize(50) 127 .fontWeight(FontWeight.Bold).onClick(() => { 128 console.info("btn click") }) 129 Button('Start Extension').onClick(() => { 130 vpnExtension.startVpnExtensionAbility(want); 131 }).width('70%').fontSize(45).margin(16) 132 Button('Stop Extension').onClick(() => { 133 console.info("btn end") 134 vpnExtension.stopVpnExtensionAbility(want); 135 }).width('70%').fontSize(45).margin(16) 136 137 }.width('100%') 138 }.height('100%') 139 } 140} 141``` 142 143After the **VPNExtensionAbility** is stopped, call [onDestroy](../reference/apis-network-kit/js-apis-VpnExtensionAbility.md#vpnextensionabilityondestroy) to destroy the VPN connection and release related resources. 144 145```ts 146import { vpnExtension, VpnExtensionAbility } from '@kit.NetworkKit'; 147import { common, Want } from '@kit.AbilityKit'; 148import { BusinessError } from '@kit.BasicServicesKit'; 149 150let context: vpnExtension.VpnExtensionContext; 151export default class MyVpnExtAbility extends VpnExtensionAbility { 152 onDestroy() { 153 let VpnConnection : vpnExtension.VpnConnection = vpnExtension.createVpnConnection(context); 154 console.info("vpn createVpnConnection: " + JSON.stringify(VpnConnection)); 155 VpnConnection.destroy().then(() => { 156 console.info("destroy success."); 157 }).catch((error : BusinessError) => { 158 console.error("destroy fail" + JSON.stringify(error)); 159 }); 160 } 161} 162``` 163 164## Service Lifecycle Management 165 166To ensure network connectivity, the system automatically stops the VPN connection when detecting that the VPN application is abnormal: 167 168- The application process that calls **startVpnExtensionAbility** exits. 169- The VPN service process is destroyed. 170 171## Description of VPN Config parameters 172 173| Name | Type | Mandatory| Description | 174| ------------------- | ------------------------------------------------------------ | ---- | ------------------------------------------------------------ | 175| addresses | Array\<[LinkAddress](../reference/apis-network-kit/js-apis-net-connection.md#linkaddress)\> | Yes | IP addresses of virtual network interface cards (vNICs). | 176| routes | Array\<[RouteInfo](../reference/apis-network-kit/js-apis-net-connection.md#routeinfo)\> | No | Routes of vNICs. Currently, a maximum of 1024 routes can be configured. | 177| dnsAddresses | Array\<string\> | No | IP addresses of DNS servers. Trusted VPN applications can access the network through these IP addresses. If this parameter is not configured, IP address allocated by the system will be used.| 178| searchDomains | Array\<string\> | No | List of DNS search domains. | 179| mtu | number | No | Maximum transmission unit (MTU), in bytes. | 180| isIPv4Accepted | boolean | No | Whether IPv4 is supported. The default value is **true**. | 181| isIPv6Accepted | boolean | No | Whether IPv6 is supported. The default value is **false**. | 182| isInternal | boolean | No | Whether the built-in VPN is supported. The default value is **false**. | 183| isBlocking | boolean | No | Whether the blocking mode is used. The default value is **false**. | 184| trustedApplications | Array\<string\> | No | Trusted VPN applications, which are represented by bundle names of the string type | 185| blockedApplications | Array\<string\> | No | Blocked VPN applications, which are represented by bundle names of the string type | 186 187**Example** 188 189```ts 190import { vpnExtension} from '@kit.NetworkKit'; 191 192let vpnConfig: vpnExtension.VpnConfig = { 193 // Configure the IP address of the vNIC. 194 addresses: [{ 195 address: { 196 address:'192.x.x.5', 197 family:1 198 }, 199 prefixLength:24 200 }], 201 // Configure route information. 202 routes: [{ 203 // Set the name of the vNIC, which has a fixed value of vpn-tun. 204 interface: 'vpn-tun', 205 destination: { 206 address: { 207 address:'10.x.x.8', 208 family:1, 209 port:8080 210 }, 211 prefixLength:24 212 }, 213 gateway: { 214 address:'10.x.x.5', 215 family:1, 216 port:8080 217 }, 218 hasGateway: false, 219 isDefaultRoute: false, 220 }], 221 // Configure the MTU. 222 mtu: 1400, 223 // Configure IP addresses of DNS serves. 224 dnsAddresses: ['223.x.x.5', '223.x.x.6'], 225 // Configure trusted VPN applications. 226 trustedApplications: ['com.test.browser'], 227 // Configure blocked VPN applications. 228 blockedApplications: ['com.test.games'], 229} 230let context: vpnExtension.VpnExtensionContext; 231 232function vpnCreate(){ 233 let VpnConnection: vpnExtension.VpnConnection = vpnExtension.createVpnConnection(context); 234 VpnConnection.create(vpnConfig).then((data) => { 235 console.info("vpn create " + JSON.stringify(data)); 236 }) 237} 238``` 239 240 241 242## VPN Demo 243 244The OpenHarmony project provides a sample application named [VPN](https://gitee.com/openharmony/applications_app_samples/tree/master/code/BasicFeature/Connectivity/VPN), which showcases how to implement the VPN service. 245