add Xposed hook for android nfc service

update AGP version

app/build.gradle

@@ -89,6 +89,7 @@ dependencies {
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:1.5.2"
     implementation 'com.google.code.gson:gson:2.8.9'
     implementation 'androidx.preference:preference-ktx:1.1.1'
+    compileOnly("de.robv.android.xposed:api:82")
     testImplementation 'junit:junit:4.13.2'
     androidTestImplementation 'androidx.test.ext:junit:1.1.3'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'

app/src/main/AndroidManifest.xml

@@ -147,6 +147,19 @@
             </intent-filter>
         </receiver>
 
+        <meta-data
+            android:name="xposedmodule"
+            android:value="true" />
+        <meta-data
+            android:name="xposeddescription"
+            android:value="@string/xposeddescription" />
+        <meta-data
+            android:name="xposedminversion"
+            android:value="51" />
+        <meta-data
+            android:name="xposedscope"
+            android:resource="@array/xposedscope" />
+
         <meta-data
             android:name="com.sec.android.support.multiwindow"
             android:value="true" />

app/src/main/assets/xposed_init

@@ -0,0 +1 @@
+cc.ioctl.nfcdevicehost.xposed.HookEntry

app/src/main/java/cc/ioctl/nfcdevicehost/xposed/HookEntry.java

@@ -0,0 +1,30 @@
+package cc.ioctl.nfcdevicehost.xposed;
+
+import de.robv.android.xposed.IXposedHookLoadPackage;
+import de.robv.android.xposed.XC_MethodHook;
+import de.robv.android.xposed.XposedHelpers;
+import de.robv.android.xposed.callbacks.XC_LoadPackage;
+
+public class HookEntry implements IXposedHookLoadPackage {
+
+    private static void initNfcServiceHook(ClassLoader classLoader) {
+        XposedHelpers.findAndHookMethod("com.android.nfc.NfcService", classLoader, "playSound", int.class, new XC_MethodHook() {
+            @Override
+            protected void beforeHookedMethod(MethodHookParam param) {
+                if (SysNfcSvcPatch.sDisableNfcDiscoverySound) {
+                    param.setResult(null);
+                }
+            }
+        });
+        SysNfcSvcPatch.startMainThread();
+    }
+
+    @Override
+    public void handleLoadPackage(XC_LoadPackage.LoadPackageParam lpparam) {
+        if ("com.android.nfc".equals(lpparam.packageName)) {
+            if (lpparam.isFirstApplication) {
+                initNfcServiceHook(lpparam.classLoader);
+            }
+        }
+    }
+}

app/src/main/java/cc/ioctl/nfcdevicehost/xposed/SysNfcSvcPatch.java

@@ -0,0 +1,194 @@
+package cc.ioctl.nfcdevicehost.xposed;
+
+import android.net.Credentials;
+import android.net.LocalServerSocket;
+import android.net.LocalSocket;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import de.robv.android.xposed.XposedBridge;
+
+public class SysNfcSvcPatch {
+
+    private static Thread sWorkingThread = null;
+    public static boolean sDisableNfcDiscoverySound = false;
+    private static boolean sShouldRunning = true;
+
+    static void run() {
+        try {
+            int myPid = android.os.Process.myPid();
+            while (sShouldRunning) {
+                LocalServerSocket localServerSocket;
+                try {
+                    localServerSocket = new LocalServerSocket("com.android.nfc/cc.ioctl.nfcdevicehost.xposed.SysNfcSvcPatch@" + myPid);
+                    while (sShouldRunning) {
+                        LocalSocket localSocket = localServerSocket.accept();
+                        Credentials cred = null;
+                        try {
+                            cred = localSocket.getPeerCredentials();
+                        } catch (IOException ignored) {
+                        }
+                        if (cred != null && cred.getUid() == 0) {
+                            localServerSocket.close();
+                            handleTransaction(localSocket);
+                            // socket is closed in handleTransaction
+                            break;
+                        } else {
+                            try {
+                                localSocket.close();
+                            } catch (IOException ignored) {
+                            }
+                        }
+                    }
+                } catch (IOException e) {
+                    XposedBridge.log("SysNfcSvcPatch: " + e.getMessage());
+                    XposedBridge.log(e);
+                    return;
+                }
+            }
+        } catch (RuntimeException e) {
+            XposedBridge.log(e);
+        }
+    }
+
+    static final int TYPE_REQUEST = 1;
+    static final int TYPE_RESPONSE = 2;
+    static final int TYPE_EVENT = 3;
+    static final byte[] EMPTY_BYTE_ARRAY = new byte[0];
+
+    static final int REQUEST_SET_NFC_SOUND_DISABLE = 0x30;
+    static final int REQUEST_GET_NFC_SOUND_DISABLE = 0x31;
+
+    static void handleTransaction(LocalSocket socket) {
+        try {
+            byte[] buffer = new byte[65536];
+            InputStream is = socket.getInputStream();
+            while (sShouldRunning) {
+                // read 4 bytes length
+                readFully(is, buffer, 0, 4);
+                int length = getInt32Le(buffer, 0);
+                if (length < 16 || length > 65535) {
+                    break;
+                }
+                // read length bytes
+                readFully(is, buffer, 0, length);
+                // uint32_t type
+                int type = getInt32Le(buffer, 0);
+                // uint32_t sequence
+                int sequence = getInt32Le(buffer, 4);
+                // uint32_t requestCode
+                int requestCode = getInt32Le(buffer, 8);
+                // uint32_t arg0
+                int arg0 = getInt32Le(buffer, 12);
+                byte[] data;
+                if (length > 16) {
+                    data = new byte[length - 16];
+                    System.arraycopy(buffer, 16, data, 0, length - 16);
+                } else {
+                    data = EMPTY_BYTE_ARRAY;
+                }
+                switch (type) {
+                    case TYPE_REQUEST:
+                        handleRequest(socket, sequence, requestCode, arg0, data);
+                        break;
+                    case TYPE_RESPONSE:
+                    case TYPE_EVENT:
+                    default:
+                        break;
+                }
+            }
+        } catch (IOException e) {
+            XposedBridge.log("SysNfcSvcPatch: " + e.getMessage());
+        }
+        try {
+            socket.close();
+        } catch (IOException ignored) {
+        }
+    }
+
+    private static void handleRequest(LocalSocket socket, int sequence, int requestCode, int arg0, byte[] data) {
+        switch (requestCode) {
+            case REQUEST_SET_NFC_SOUND_DISABLE: {
+                sDisableNfcDiscoverySound = (arg0 != 0);
+                sendResponse(socket, sequence, 0, 0, null);
+                break;
+            }
+            case REQUEST_GET_NFC_SOUND_DISABLE: {
+                sendResponse(socket, sequence, sDisableNfcDiscoverySound ? 1 : 0, 0, null);
+                break;
+            }
+            default: {
+                sendResponse(socket, sequence, -1, -1, null);
+            }
+        }
+    }
+
+    static void sendResponse(LocalSocket socket, int sequence, int resultCode, int errCode, byte[] data) {
+        if (data == null) {
+            data = EMPTY_BYTE_ARRAY;
+        }
+        byte[] bufferLen4 = new byte[4];
+        putInt32Le(bufferLen4, 0, data.length + 16);
+        byte[] buffer = new byte[16 + data.length];
+        putInt32Le(buffer, 0, TYPE_RESPONSE);
+        putInt32Le(buffer, 4, sequence);
+        putInt32Le(buffer, 8, resultCode);
+        putInt32Le(buffer, 12, errCode);
+        System.arraycopy(data, 0, buffer, 16, data.length);
+        try {
+            OutputStream os = socket.getOutputStream();
+            os.write(bufferLen4);
+            os.write(buffer);
+            os.flush();
+        } catch (IOException e) {
+            XposedBridge.log("SysNfcSvcPatch: " + e.getMessage());
+        }
+    }
+
+    public static synchronized void startMainThread() {
+        if (sWorkingThread == null || !sWorkingThread.isAlive()) {
+            sWorkingThread = new Thread(SysNfcSvcPatch::run);
+            sWorkingThread.start();
+        }
+    }
+
+    static void readFully(InputStream is, byte[] buffer, int offset, int length) throws IOException {
+        int remaining = length;
+        while (remaining > 0) {
+            int read = is.read(buffer, offset, remaining);
+            if (read < 0) {
+                throw new IOException("Unexpected EOF");
+            }
+            remaining -= read;
+            offset += read;
+        }
+    }
+
+    /**
+     * Read a little-endian 32-bit integer from the given byte array.
+     *
+     * @param buffer The byte array to read from.
+     * @param offset The offset to start reading from.
+     * @return The 32-bit integer read.
+     */
+    static int getInt32Le(byte[] buffer, int offset) {
+        return (buffer[offset] & 0xFF) | ((buffer[offset + 1] & 0xFF) << 8)
+                | ((buffer[offset + 2] & 0xFF) << 16) | ((buffer[offset + 3] & 0xFF) << 24);
+    }
+
+    /**
+     * Put a little-endian 32-bit integer to the given byte array.
+     *
+     * @param buffer The byte array to write to.
+     * @param offset The offset to start writing to.
+     * @param value  the value to put
+     */
+    static void putInt32Le(byte[] buffer, int offset, int value) {
+        buffer[offset] = (byte) (value & 0xFF);
+        buffer[offset + 1] = (byte) ((value >> 8) & 0xFF);
+        buffer[offset + 2] = (byte) ((value >> 16) & 0xFF);
+        buffer[offset + 3] = (byte) ((value >> 24) & 0xFF);
+    }
+}

app/src/main/res/values-zh-rCN/strings.xml

@@ -70,5 +70,6 @@ NCI Host 的开发人员不对使用此应用程序造成的任何损失负责
     <string name="action_decoder_config">解码选项</string>
     <string name="ui_hal_dump_decoder_config_title">解码选项</string>
     <string name="action_confirm">确认</string>
+    <string name="xposeddescription">NFC 系统服务附加功能</string>
 
 </resources>

app/src/main/res/values/arrays.xml

@@ -9,8 +9,14 @@
         <item>reply</item>
         <item>reply_all</item>
     </string-array>
+
     <string-array name="ui_hal_dump_decoder_config_items">
         <item>None(raw syscall dump)</item>
         <item>NCI protocol</item>
     </string-array>
+
+    <string-array name="xposedscope">
+        <item>com.android.nfc</item>
+    </string-array>
+
 </resources>

app/src/main/res/values/strings.xml

@@ -99,4 +99,5 @@ By using this application, you accept all responsibility using it and agree that
     <string name="action_decoder_config">Decoder properties</string>
     <string name="ui_hal_dump_decoder_config_title">Decoder Properties</string>
     <string name="action_confirm">Confirm</string>
+    <string name="xposeddescription">Extra features for NFC service.</string>
 </resources>

build.gradle

@@ -7,7 +7,7 @@ buildscript {
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.0.3'
+        classpath 'com.android.tools.build:gradle:7.0.4'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files
@@ -19,6 +19,7 @@ allprojects {
         google()
         mavenCentral()
         maven { url 'https://jitpack.io' }
+        maven { url 'https://api.xposed.info/' }
     }
 }