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安卓9 设置热点固定IP (Xposed)

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安卓12 固定Wifi热点IP (Xposed)

安卓10、11 固定Wifi热点IP (Xposed)

项目地址

SoftApHelper

概述

手机系统升级到安卓9之后，开热点的主机IP地址是随机的。其他设备设置代理很不方便，于是考虑固定热点IP。

Hook点

安卓9

com.android.server.connectivity.tethering.TetherInterfaceStateMachine的getRandomWifiIPv4Address函数。

TetherInterfaceStateMachine.java#259

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private String getRandomWifiIPv4Address()

安卓8热点开启流程


图源：android8.0热点打开流程，从Setting到framework

跟踪源码

最终定位到com.android.server.connectivity.tethering.TetherInterfaceStateMachine类（源代码）

函数调用链：startIPv4-configureIPv4-getRandomWifiIPv4Address

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private boolean configureIPv4(boolean enabled) {
    // ...
else if (mInterfaceType == ConnectivityManager.TETHERING_WIFI) {
    ipAsString = getRandomWifiIPv4Address();
    prefixLen = WIFI_HOST_IFACE_PREFIX_LENGTH;
}
    // ...
}

调用getRandomWifiIPv4Address函数生成主机IP地址后，转换为LinkAddress，最终调用ifcg.setLinkAddress设置IP：

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final LinkAddress linkAddr;
try {
    final InterfaceConfiguration ifcg = mNMService.getInterfaceConfig(mIfaceName);
    if (ifcg == null) {
        mLog.e("Received null interface config");
        return false;
    }

    InetAddress addr = NetworkUtils.numericToInetAddress(ipAsString);
    linkAddr = new LinkAddress(addr, prefixLen);
    ifcg.setLinkAddress(linkAddr);
// ...
}

查找getRandomWifiIPv4Address的交叉引用，发现只有这一处。直接修改返回值，即可固定IP。

解决方案

使用Xposed框架Hook该函数（过滤包名android），设置返回值为192.168.43.1即可

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public class Hook implements IXposedHookLoadPackage {

    private static final String classname = "com.android.server.connectivity.tethering.TetherInterfaceStateMachine";
    private static final String methodname = "getRandomWifiIPv4Address";
    private static final String WIFI_HOST_IFACE_ADDR = "192.168.43.1";

    @Override
    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam lpparam) throws Throwable {
        if (lpparam.packageName.equals("android")) {
            Class<?> clz = XposedHelpers.findClass(classname, lpparam.classLoader);

            findAndHookMethod(clz, methodname, new XC_MethodReplacement() {
                @Override
                protected Object replaceHookedMethod(MethodHookParam param) {
                    return WIFI_HOST_IFACE_ADDR;
                }
            });
        }
    }

}

参考

How can I permanently change my hotspot tethering IP address?