Android系统中如何添加USB网络共享

类别

需求

索引类别

USB网络共享

问题描述

平台是RT1296,在Android系统中已经有支持USB网络共享，但相应的产品系统中还未开启USB网络共享，那么这个时候就需要添加USB网络共享的一些配置，使得产品支持此功能。（以下是个人的一些理解，如有错误，请各位大佬多多指教）

代码关联

对应的代码修改部分如下：

①对应内核中添加配置（系统中添加USB网络驱动）

@@ -837,3 +837,6 @@ CONFIG_ZRAM=yCONFIG_ZRAM_LZ4_COMPRESS=yCONFIG_ZSMALLOC=y# CONFIG_ZSMALLOC_STAT is not set
+CONFIG_USB_USBNET=y
+CONFIG_USB_IPHETH=y
+CONFIG_USB_NET_RNDIS_HOST=y

②在init.rc中增加两个针对usb0的配置服务，才能让framework配置得了usb0网卡(服务是是USB网络共享的核心)

@@ -134,3 +134,16 @@ on property:persist.iso.state=unmounted
#在开机启动的时候会发送一个bootcomplete广播，接收广播后启动scdetect、rootshellserviceon property:dev.bootcomplete=1start scdetectstart rootshellservice
#启动usb网络分配dhcp
+service dhcpcd_usb0 /system/bin/dhcpcd -ABDKL -f/system/etc/dhcpcd/dhcpcd.conf
+    class main
+    disabled
+    oneshot
+    seclabel u:r:dhcp:s0
#启动usb网络分配ip
+service iprenew_usb0 /system/bin/dhcpcd -n
+    class main
+    disabled
+    oneshot
+    seclabel u:r:dhcp:s0

③对应Android源码，frameworks中添加配置(这边主要是讲述网络是如何启动的，是选择那个网络)

/frameworks/base/core/res/res/values/config.xml <bool name="config_enableMonitorInputSource">true</bool>
-    <string translatable="false" name="config_ethernet_iface_regex">eth\\d</string>
+    <string translatable="false" name="config_ethernet_iface_regex">eth\\d|usb\\d</string>

上面的作用是提供两种网络的方式，一种是以太网络，一种是走usb共享

    /frameworks/opt/net/ethernet/java/com/android/server/ethernet/EthernetNetworkFactory.javapublic synchronized void start(Context context, Handler target) {Log.i(TAG, "monitoring start");// The services we use.IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);mNMService = INetworkManagementService.Stub.asInterface(b);mEthernetManager = (EthernetManager) context.getSystemService(Context.ETHERNET_SERVICE);//在这里就获取上面设定config_ethernet_iface_regex的值mIfaceMatch = context.getResources().getString(com.android.internal.R.string.config_ethernet_iface_regex);// Create and register our NetworkFactory.mFactory = new LocalNetworkFactory(NETWORK_TYPE, context, target.getLooper());mFactory.setCapabilityFilter(mNetworkCapabilities);mFactory.setScoreFilter(-1); // this set high when we have an ifacemFactory.register();mContext = context;// Start tracking interface change events.mInterfaceObserver = new InterfaceObserver();try {mNMService.registerObserver(mInterfaceObserver);} catch (RemoteException e) {Log.e(TAG, "Could not register InterfaceObserver " + e);}// If an Ethernet interface is already connected, start tracking that.// Otherwise, the first Ethernet interface to appear will be tracked.try {final String[] ifaces = mNMService.listInterfaces();for (String iface : ifaces) {synchronized(this) {//在这里判断是采用哪个网络if (maybeTrackInterface(iface)) { // We have our interface. Track it.// Note: if the interface already has link (e.g., if we// crashed and got restarted while it was running),// we need to fake a link up notification so we start// configuring it. Since we're already holding the lock,// any real link up/down notification will only arrive// after we've done this.if (mNMService.getInterfaceConfig(iface).hasFlag("running")) {updateInterfaceState(iface, true);}break;}}}****}}//在这边可以选择是走那个网络是eth还是usb         private boolean maybeTrackInterface(String iface) {// If we don't already have an interface, and if this interface matches// our regex, start tracking it.if (!iface.matches(mIfaceMatch) || isTrackingInterface())return false;if(UbusRpc.isOpenWrt() && !UbusRpc.isOttWifi()){if(!iface.equals("eth9"))return false;} else if(!iface.equals(SystemProperties.get("net.eth.iface", "eth0"))){return false;}Log.d(TAG, "Started tracking interface " + iface);setInterfaceUp(iface);return true;}

④最后在设置一个属性值:setprop net.eth.iface usb0/eth0 （usb0强制网络走手机USB网络共享）

应用层发送一个广播，这样就可以自由的切换是使用USB还是以太网。

 Intent intent = new Intent("rtk.intent.action.SET_ETH_IFACE");intent.putExtra("EXTRA_ETH_IFACE"," usb0/eth0 ");sendBroadcast(intent);

对应frameworks的接收应用发送的广播代码：

/frameworks/opt/net/ethernet/java/com/android/server/ethernet/EthernetServiceImpl.javaprivate final BroadcastReceiver mIntentReceiver = new BroadcastReceiver(){@Overridepublic void onReceive(Context context, Intent intent) {String action = intent.getAction();if("rtk.intent.action.SET_ETH_IFACE".equals(action)){String iface = intent.getStringExtra("EXTRA_ETH_IFACE");if(iface==null) iface="eth0";SystemProperties.set("net.eth.iface", iface);Log.i(TAG, "restart EthernetNetworkFactory");enforceConnectivityInternalPermission();synchronized (mIpConfiguration) {mTracker.stop(); //重启网络，即调用第③步的startmTracker.start(mContext, mHandler); }}}};

如果没有效果，请排查一下/sys/class/net/中是否有新生成一个usb0的节点，如果没有生成的话排查第①第②步是否正常开启。

知识拓展

参考资料：https://blog.csdn.net/tankai19880619/article/details/44559419?_t=t

改进建议

若有错误请指正，悉心接受大佬的指点谢谢 ! ^v。

工作记录。。。。。