TetheringService 启动流程

SystemServer.java

private static final String TETHERING_CONNECTOR_CLASS = "android.net.ITetheringConnector";
...
            t.traceBegin("StartTethering");
            try {
                // TODO: hide implementation details, b/146312721.
                ConnectivityModuleConnector.getInstance().startModuleService(
                        TETHERING_CONNECTOR_CLASS,
                        PERMISSION_MAINLINE_NETWORK_STACK, service -> {
                            ServiceManager.addService(Context.TETHERING_SERVICE, service,
                                    false /* allowIsolated */,
                                    DUMP_FLAG_PRIORITY_HIGH | DUMP_FLAG_PRIORITY_NORMAL);
                        });
            } catch (Throwable e) {
                reportWtf("starting Tethering", e);
            }
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开机systemserver 启动，调用ConnectivityModuleConnector.getInstance().startModuleService
接下来，来分析startModuleService流程

    public void startModuleService(
            @NonNull String serviceIntentBaseAction,
            @NonNull String servicePermissionName,
            @NonNull ModuleServiceCallback callback) {
        log("Starting networking module " + serviceIntentBaseAction);

        final PackageManager pm = mContext.getPackageManager();

        // Try to bind in-process if the device was shipped with an in-process version
        1.获取tetherservice name，传入参数inSystemProcess ：true
        Intent intent = mDeps.getModuleServiceIntent(pm, serviceIntentBaseAction,
                servicePermissionName, true /* inSystemProcess */);

        // Otherwise use the updatable module version
        if (intent == null) {
            intent = mDeps.getModuleServiceIntent(pm, serviceIntentBaseAction,
                    servicePermissionName, false /* inSystemProcess */);
            log("Starting networking module in network_stack process");
        } else {
            log("Starting networking module in system_server process");
        }

        if (intent == null) {
            maybeCrashWithTerribleFailure("Could not resolve the networking module", null);
            return;
        }

        final String packageName = intent.getComponent().getPackageName();

        // Start the network stack. The service will be added to the service manager by the
        // corresponding client in ModuleServiceCallback.onModuleServiceConnected().
        //启动TetherService 服务
        if (!mContext.bindServiceAsUser(
                intent, new ModuleServiceConnection(packageName, callback),
                Context.BIND_AUTO_CREATE | Context.BIND_IMPORTANT, UserHandle.SYSTEM)) {
            maybeCrashWithTerribleFailure(
                    "Could not bind to networking module in-process, or in app with "
                            + intent, packageName);
            return;
        }

        log("Networking module service start requested");
    }
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1.通过private static final String TETHERING_CONNECTOR_CLASS = “android.net.ITetheringConnector”，来获取TetheringService对于的报名类名，接下来看看mDeps.getModuleServiceIntent 流程

	private static final String IN_PROCESS_SUFFIX = ".InProcess";
    private static class DependenciesImpl implements Dependencies {
        @Nullable
        @Override
        public Intent getModuleServiceIntent(
                @NonNull PackageManager pm, @NonNull String serviceIntentBaseAction,
                @NonNull String servicePermissionName, boolean inSystemProcess) {
            final Intent intent =
                    new Intent(inSystemProcess
                    		//2.如果参数inSystemProcess：true serviceIntentBaseAction 字串后面+“.InProcess”
                            ? serviceIntentBaseAction + IN_PROCESS_SUFFIX
                            : serviceIntentBaseAction);
            final ComponentName comp = intent.resolveSystemService(pm, 0);
            if (comp == null) {
                return null;
            }
            intent.setComponent(comp);

            final int uid;
            try {
                uid = pm.getPackageUidAsUser(comp.getPackageName(), UserHandle.USER_SYSTEM);
            } catch (PackageManager.NameNotFoundException e) {
                throw new SecurityException(
                        "Could not check network stack UID; package not found.", e);
            }

            final int expectedUid =
                    inSystemProcess ? Process.SYSTEM_UID : Process.NETWORK_STACK_UID;
            if (uid != expectedUid) {
                throw new SecurityException("Invalid network stack UID: " + uid);
            }

            if (!inSystemProcess) {
                checkModuleServicePermission(pm, comp, servicePermissionName);
            }

            return intent;
        }
    }
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上面判断inSystemProcess添加不同的AndroidManifest.xml

区别在对于的报名不同
com.android.networkstack.tethering
com.android.networkstack.tethering.inprocess
但是TetheringService.java是同一个。

接下来，我们看看TetheringService 启动

    @Override
    public void onCreate() {
    	//初始化tether依赖关系
        final TetheringDependencies deps = makeTetheringDependencies();
        // The Tethering object needs a fully functional context to start, so this can't be done
        // in the constructor.
        //初始化tether 连接器
        mConnector = new TetheringConnector(makeTethering(deps), TetheringService.this);
    }
    
    @VisibleForTesting
    public Tethering makeTethering(TetheringDependencies deps) {
        System.loadLibrary("tetherutilsjni");
        return new Tethering(deps);
    }
        private static class TetheringConnector extends ITetheringConnector.Stub {
        private final TetheringService mService;
        private final Tethering mTethering;

        TetheringConnector(Tethering tether, TetheringService service) {
            mTethering = tether;
            mService = service;
        }

        @Override
        public void tether(String iface, String callerPkg, IIntResultListener listener) {
            if (checkAndNotifyCommonError(callerPkg, listener)) return;

            try {
                listener.onResult(mTethering.tether(iface));
            } catch (RemoteException e) { }
        }

        @Override
        public void untether(String iface, String callerPkg, IIntResultListener listener) {
            if (checkAndNotifyCommonError(callerPkg, listener)) return;

            try {
                listener.onResult(mTethering.untether(iface));
            } catch (RemoteException e) { }
        }

        @Override
        public void setUsbTethering(boolean enable, String callerPkg, IIntResultListener listener) {
            if (checkAndNotifyCommonError(callerPkg, listener)) return;

            try {
                listener.onResult(mTethering.setUsbTethering(enable));
            } catch (RemoteException e) { }
        }

        @Override
        public void startTethering(TetheringRequestParcel request, String callerPkg,
                IIntResultListener listener) {
            if (checkAndNotifyCommonError(callerPkg,
                    request.exemptFromEntitlementCheck /* onlyAllowPrivileged */,
                    listener)) {
                return;
            }

            mTethering.startTethering(request, listener);
        }

        @Override
        public void stopTethering(int type, String callerPkg, IIntResultListener listener) {
            if (checkAndNotifyCommonError(callerPkg, listener)) return;

            try {
                mTethering.stopTethering(type);
                listener.onResult(TETHER_ERROR_NO_ERROR);
            } catch (RemoteException e) { }
        }

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TetheringService 主要处理事务的其实是mTethering

如何调用TetherService

    public void setHotspotEnabled(boolean enabled) {
        if (mWaitingForTerminalState) {
            if (DEBUG) Log.d(TAG, "Ignoring setHotspotEnabled; waiting for terminal state.");
            return;
        }
        if (enabled) {
            mWaitingForTerminalState = true;
            if (DEBUG) Log.d(TAG, "Starting tethering");
            mTetheringManager.startTethering(new TetheringRequest.Builder(TETHERING_WIFI).build(),
                    ConcurrentUtils.DIRECT_EXECUTOR,
                    new TetheringManager.StartTetheringCallback() {
                        @Override
                        public void onTetheringFailed(final int result) {
                            if (DEBUG) Log.d(TAG, "onTetheringFailed");
                            maybeResetSoftApState();
                            fireHotspotChangedCallback();
                        }
                    });
        } else {
            mTetheringManager.stopTethering(ConnectivityManager.TETHERING_WIFI);
        }
    }
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通过TetheringManager 调用TetherService–Tether

对于Tether管理代码目录