android 添加USB网卡并配置DNS

工作需要，需要使用TBox分享的网络，Android将TBox当作一个USB网卡，接下来就简单了，配置这个网卡的信息即可。

加载默认网卡的信息在frameworks/opt/net/ethernet/java/com/android/server/ethernet/EthernetTracker.java中

    EthernetTracker(Context context, Handler handler) {
        mHandler = handler;

        // The services we use.
        IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);
        mNMService = INetworkManagementService.Stub.asInterface(b);

        // Interface match regex.
        mIfaceMatch = context.getResources().getString(
                com.android.internal.R.string.config_ethernet_iface_regex);

        // Read default Ethernet interface configuration from resources
        final String[] interfaceConfigs = context.getResources().getStringArray(
                com.android.internal.R.array.config_ethernet_interfaces);
        for (String strConfig : interfaceConfigs) {
            parseEthernetConfig(strConfig);
        }   

        mConfigStore = new EthernetConfigStore();

        NetworkCapabilities nc = createNetworkCapabilities(true /* clear default capabilities */);
        mFactory = new EthernetNetworkFactory(handler, context, nc);
        mFactory.register();
    }  

网卡配置文件在frameworks/base/core/res/res/values/config.xml

    <string-array translatable="false" name="config_ethernet_interfaces">
        <item>eth0;30;12,13,14,15;ip=10.100.114.139/24</item>
        <item>usb0;40;12,13,14,15,16</item>
        <item>wwan0;45;12,13,14,15,16;ip=192.168.1.6/24 gateway=192.168.1.5 dns=114.114.114.114</item>
    </string-array>

wwan0是添加的网卡信息