rk3288 android以太网和wifi共存

使用以太网做内网访问，wifi做外网访问，也就是说wifi的优先级应该比以太网高，当wifi内网无法访问时，才发切换到以太网使用

首先是准备

1、以下四个变量代表着安卓平台不同网络的评分，这些评分用于网络选择仲裁，评分越高就会优先选择。

NETWORK_SCORE,
WIFI_BASE_SCORE,
NETWORK_SCORE,
TELEPHONY_NETWORK_SCORE

2、这四个变量分别出自如下安卓SDK文件：

NETWORK_SCORE 有两个网络都用这个定义，一个是以太网，另一个是蓝牙

a. 以太网如下：

./frameworks/opt/net/ethernet/java/com/android/server/ethernet/EthernetNetworkFactory.java:97
private static final int NETWORK_SCORE = 70

b. 蓝牙的如下：

./packages/apps/Bluetooth/src/com/android/bluetooth/pan/BluetoothTetheringNetworkFactory.java:52
private static final int NETWORK_SCORE = 69;

c. Wifi的如下：

./frameworks/base/core/java/android/net/NetworkAgent.java:94
public static final int WIFI_BASE_SCORE = 60;

d. 移动网络的如下：

./frameworks/opt/telephony/src/java/com/android/internal/telephony/dataconnection/TelephonyNetworkFactory.java:61
private final static int TELEPHONY_NETWORK_SCORE = 50;

3、从上面四种网络的评分，我们就知道了，安卓平台网络选择顺序：以太网，蓝牙PAN, WiFi, 最后移动网络。

下面是修改过程

1.修改 frameworks/base/core/java/android/net/NetworkFactory.java

evalRequest 方法 注释两行

private void evalRequest(NetworkRequestInfo n) {
        if (VDBG) log("evalRequest");
        if (n.requested == false && n.score < mScore &&
                n.request.networkCapabilities.satisfiedByNetworkCapabilities(
                mCapabilityFilter) && acceptRequest(n.request, n.score)) {
            if (VDBG) log("  needNetworkFor");
            needNetworkFor(n.request, n.score);
            n.requested = true;
            Log.d(TAG, "needNetworkFor");
        } else if (n.requested == true &&
                (n.score > mScore || n.request.networkCapabilities.satisfiedByNetworkCapabilities(
                mCapabilityFilter) == false || acceptRequest(n.request, n.score) == false)) {
            if (VDBG) log("  releaseNetworkFor");
            Log.d(TAG, "releaseNetworkFor");
            //releaseNetworkFor(n.request);//注释这一句
            //n.requested = false;//注释这一句
        } else {
            if (VDBG) log("  done");
        }
    }

2.修改frameworks/opt/net/ethernet/java/com/android/server/ethernet/EthernetNetworkFactory.java文件修改 NETWORK_SCORE=30 降低优先级

这样以太网和wifi都能连接成功

Android12及以上的网络策略不太一致

Android 12 

frameworks\opt\net\ethernet\java\com\android\server\ethernet\EthernetNetworkFactory.java

需要修改下面的得分

private static final SparseArray sTransports = new SparseArray();
        static {
            // LowpanInterfaceTracker.NETWORK_SCORE
            sTransports.put(NetworkCapabilities.TRANSPORT_LOWPAN,
                    new TransportInfo(ConnectivityManager.TYPE_NONE, 30));
            // WifiAwareDataPathStateManager.NETWORK_FACTORY_SCORE_AVAIL
            sTransports.put(NetworkCapabilities.TRANSPORT_WIFI_AWARE,
                    new TransportInfo(ConnectivityManager.TYPE_NONE, 1));
            // EthernetNetworkFactory.NETWORK_SCORE
            sTransports.put(NetworkCapabilities.TRANSPORT_ETHERNET,
                    new TransportInfo(ConnectivityManager.TYPE_ETHERNET, 70));
            // BluetoothTetheringNetworkFactory.NETWORK_SCORE
            sTransports.put(NetworkCapabilities.TRANSPORT_BLUETOOTH,
                    new TransportInfo(ConnectivityManager.TYPE_BLUETOOTH, 69));
            // WifiNetworkFactory.SCORE_FILTER / NetworkAgent.WIFI_BASE_SCORE
            sTransports.put(NetworkCapabilities.TRANSPORT_WIFI,
                    new TransportInfo(ConnectivityManager.TYPE_WIFI, 60));
            // TelephonyNetworkFactory.TELEPHONY_NETWORK_SCORE
            sTransports.put(NetworkCapabilities.TRANSPORT_CELLULAR,
                    new TransportInfo(ConnectivityManager.TYPE_MOBILE, 50));
        }

frameworks\libs\net\common\device\android\net\NetworkFactoryLegacyImpl.java

原因是updateAgent变了

Android 9

private void updateAgent() {
            if (mNetworkAgent == null) return;
            if (DBG) {
                Log.i(TAG, "Updating mNetworkAgent with: " +
                        mCapabilities + ", " +
                        mNetworkInfo + ", " +
                        mLinkProperties);
            }
            mNetworkAgent.sendNetworkCapabilities(mCapabilities);
            mNetworkAgent.sendNetworkInfo(mNetworkInfo);
            mNetworkAgent.sendLinkProperties(mLinkProperties);
            // never set the network score below 0.
            mNetworkAgent.sendNetworkScore(mLinkUp? NETWORK_SCORE : 0);
        }

Android12

private void updateAgent() {
            if (mNetworkAgent == null) return;
            if (DBG) {
                Log.i(TAG, "Updating mNetworkAgent with: " +
                        mCapabilities + ", " +
                        mLinkProperties);
            }
            mNetworkAgent.sendNetworkCapabilities(mCapabilities);
            mNetworkAgent.sendLinkProperties(mLinkProperties);
 
            // As a note, getNetworkScore() is fairly expensive to calculate. This is fine for now
            // since the agent isn't updated frequently. Consider caching the score in the future if
            // agent updating is required more often
            mNetworkAgent.sendNetworkScore(getNetworkScore());
        }

/**
         * Determines the network score based on the transport associated with the interface.
         * Ethernet interfaces could propagate a transport types forward. Since we can't
         * get more information about the statuses of the interfaces on the other end of the local
         * interface, we'll best-effort assign the score as the base score of the assigned transport
         * when the link is up. When the link is down, the score is set to zero.
         *
         * This function is called with the purpose of assigning and updating the network score of
         * the member NetworkAgent.
         */
        private int getNetworkScore() {
            // never set the network score below 0.
            if (!mLinkUp) {
                return 0;
            }
 
            int[] transportTypes = mCapabilities.getTransportTypes();
            if (transportTypes.length < 1) {
                Log.w(TAG, "Network interface '" + mLinkProperties.getInterfaceName() + "' has no "
                        + "transport type associated with it. Score set to zero");
                return 0;
            }
            TransportInfo transportInfo = sTransports.get(transportTypes[0], /* if dne */ null);
            if (transportInfo != null) {
                return transportInfo.mScore;
            }
            return 0;
        }

所谓共存就是让两个网络同时使用，如果想让哪个网络作为外网，则该网络优先级要高于内网的网络，即可达到外网用来上网的需求，那么要想共存，就必须到从低优先级网络切换到优先级高的网络时，不要做断开操作，即可达到，两个网络同时存在的需求，做到以上两点，我们便满足了2个网络同时存在，且使用优先级高的外网上网

到了android12已经废弃了这种直接的打分机制，使用了policy机制，具体可参考
packages/modules/Connectivity/service/src/com/android/server/connectivity/NetworkRanker.java
但由于这种评分机制涉及的条件比较多，对于我们做网络共存这个需求来说更加复杂，
对此android开发者也给我么预留了以前的评分方案，只要我们简单的将
USE_POLICY_RANKING = false; 即可
 

 /**
     * Find the best network satisfying this request among the list of passed networks.
     */
    @Nullable
    public NetworkAgentInfo getBestNetwork(@NonNull final NetworkRequest request,
            @NonNull final Collection nais,
            @Nullable final NetworkAgentInfo currentSatisfier) {
        final ArrayList candidates = filter(nais, nai -> nai.satisfies(request));
        if (candidates.size() == 1) return candidates.get(0); // Only one potential satisfier
        if (candidates.size() <= 0) return null; // No network can satisfy this request
        if (USE_POLICY_RANKING) {
            return getBestNetworkByPolicy(candidates, currentSatisfier);
        } else {
            return getBestNetworkByLegacyInt(candidates);
        }
    }