NetworkManagementService 解读

在前面文章介绍了其自身定义的接口功能提供给客户端：https://blog.youkuaiyun.com/Vince_/article/details/115203280

在与底层 netd 通信过程中实际上采用了 NetdUnsolicitedEventListener 内部类定义的接口进行，它自身作为服务端，netd 作为客户端对该功能进行引用调用。

NetdUnsolicitedEventListener 的 定义在 NetworkManagementService.java 中，不过其继承实现了接口类 INetdUnsolicitedEventListener.Stub，其定义如下：

文件：system/netd/server/binder/android/net/INetdUnsolicitedEventListener.aidl

/**
 * Unsolicited netd events which are reported by the kernel via netlink.
 * This one-way interface groups asynchronous notifications sent
 * by netd to any process that registered itself via INetd.registerUnsolEventListener.
 *
 * {@hide}
 */
oneway interface INetdUnsolicitedEventListener {

    /**
     * Notifies that an interface has been idle/active for a certain period of time.
     * It is the event for idletimer.
     *
     * @param isActive true for active status, false for idle
     * @param timerLabel unique identifier of the idletimer.
     *              Since NMS only set the identifier as int, only report event with int label.
     * @param timestampNs kernel timestamp of this event, 0 for no timestamp
     * @param uid uid of this event, -1 for no uid.
     *            It represents the uid that was responsible for waking the radio.
     */
    void onInterfaceClassActivityChanged(
            boolean isActive,
            int timerLabel,
            long timestampNs,
            int uid);

    /**
     * Notifies that a specific interface reached its quota limit.
     *
     * @param alertName alert name of the quota limit
     * @param ifName interface which reached the limit
     */
    void onQuotaLimitReached(@utf8InCpp String alertName, @utf8InCpp String ifName);

    /**
     * Provides information on IPv6 DNS servers on a specific interface.
     *
     * @param ifName interface name
     * @param lifetimeS lifetime for the DNS servers in seconds
     * @param servers the address of servers.
     *                  e.g. IpV6: "2001:4860:4860::6464"
     *
     */
    void onInterfaceDnsServerInfo(
            @utf8InCpp String ifName, long lifetimeS, in @utf8InCpp String[] servers);

    /**
     * Notifies that an address has updated on a specific interface.
     *
     * @param addr address that is being updated
     * @param ifName the name of the interface on which the address is configured
     * @param flags address flags, see ifa_flags in if_addr.h
     * @param scope current scope of the address
     */
    void onInterfaceAddressUpdated(
            @utf8InCpp String addr,
            @utf8InCpp String ifName,
            int flags,
            int scope);

    /**
     * Notifies that an address has been removed on a specific interface.
     *
     * @param addr address of this change
     * @param ifName the name of the interface that changed addresses
     * @param flags address flags, see ifa_flags in if_addr.h
     * @param scope address address scope
     */
    void onInterfaceAddressRemoved(
            @utf8InCpp String addr,
            @utf8InCpp String ifName,
            int flags,
            int scope);

    /**
     * Notifies that an interface has been added.
     *
     * @param ifName the name of the added interface
     */
    void onInterfaceAdded(@utf8InCpp String ifName);

    /**
     * Notifies that an interface has been removed.
     *
     * @param ifName the name of the removed interface
     */
    void onInterfaceRemoved(@utf8InCpp String ifName);

    /**
     * Notifies that the status of the specific interface has changed.
     *
     * @param ifName the name of the interface that changed status
     * @param up true for interface up, false for down
     */
    void onInterfaceChanged(@utf8InCpp String ifName, boolean up);

    /**
     * Notifies that the link state of the specific interface has changed.
     *
     * @param ifName the name of the interface whose link state has changed
     * @param up true for interface link state up, false for link state down
     */
    void onInterfaceLinkStateChanged(@utf8InCpp String ifName, boolean up);

    /**
     * Notifies that an IP route has changed.
     *
     * @param updated true for update, false for remove
     * @param route destination prefix of this route, e.g., "2001:db8::/64"
     * @param gateway address of gateway, empty string for no gateway
     * @param ifName interface name of this route, empty string for no interface
     */
    void onRouteChanged(
            boolean updated,
            @utf8InCpp String route,
            @utf8InCpp String gateway,
            @utf8InCpp String ifName);

    /**
     * Notifies that kernel has detected a socket sending data not wrapped
     * inside a layer of SSL/TLS encryption.
     *
     * @param uid uid of this event
     * @param hex packet content in hex format
     */
    void onStrictCleartextDetected(int uid, @utf8InCpp String hex);
}

可以看到主要有如下几个接口：

• void onInterfaceClassActivityChanged(boolean isActive, int timerLabel, long timestampNs, int uid);
• void onQuotaLimitReached(String alertName, String ifName);
• void onInterfaceDnsServerInfo(String ifName, long lifetimeS, String[] servers);
• void onInterfaceAddressUpdated(String addr, String ifName, int flags, int scope);
• void onInterfaceAddressRemoved(String addr, String ifName, int flags, int scope);
• void onInterfaceAdded(String ifName);
• void onInterfaceRemoved(String ifName);
• void onInterfaceChanged(String ifName, boolean up);
• void onInterfaceLinkStateChanged(String ifName, boolean up);
• void onRouteChanged(boolean updated, String route, String gateway, String ifName);
• void onStrictCleartextDetected(int uid, String hex);

主要实现了接口 Active 状态改变，配合用完，Dns 信息，地址更新或删除，接口添加、删除或者更新，接口链接状态变化，路由变更，严格路由信息等的回调。这里看起来是回调形式的定义，其实并非回调，而是一个 binder 的 Client 和 Server 接口的直接调用。binder 接口以私有的方式从 NetworkManagementService 类进程传递到 netd 后台进程中，以客户端的形式存在进行调用。