Implement license activation via QR code

It's now possible to use a QR code to activate licenses on
non-Play builds of the app. This comes handy on TV devices

app/build.gradle

@@ -87,4 +87,5 @@ dependencies {
     implementation 'cat.ereza:customactivityoncrash:2.3.0'
     implementation 'com.github.KaKaVip:Android-Flag-Kit:v0.1'
     implementation 'com.github.AppIntro:AppIntro:6.2.0'
+    implementation 'com.github.androidmads:QRGenerator:1.0.1'
 }

app/src/main/java/com/emanuelef/remote_capture/Billing.java

@@ -115,13 +115,18 @@ public class Billing {
     public void connectBilling() {}
     public void disconnectBilling() {}
 
-    public void setLicense(String license) {
-        if(!isValidLicense(license))
+    public boolean setLicense(String license) {
+        boolean valid = true;
+        if(!isValidLicense(license)) {
             license = "";
+            valid = false;
+        }
 
         mPrefs.edit()
                 .putString("license", license)
                 .apply();
+
+        return valid;
     }
 
     public boolean isValidLicense(String license) {

app/src/main/java/com/emanuelef/remote_capture/Utils.java

@@ -60,6 +60,7 @@ import android.os.Handler;
 import android.os.Looper;
 import android.provider.MediaStore;
 import android.provider.OpenableColumns;
+import android.provider.Settings;
 import android.text.SpannableString;
 import android.text.SpannedString;
 import android.text.TextUtils;
@@ -139,6 +140,7 @@ import javax.net.ssl.HttpsURLConnection;
 public class Utils {
     static final String TAG = "Utils";
     public static final String INTERACT_ACROSS_USERS = "android.permission.INTERACT_ACROSS_USERS";
+    public static final String PCAPDROID_WEBSITE = "https://pcapdroid.org";
     public static final int PER_USER_RANGE = 100000;
     public static final int UID_UNKNOWN = -1;
     public static final int UID_NO_FILTER = -2;
@@ -1410,6 +1412,10 @@ public class Utils {
                 "OS version: " + getOsVersion() + "\n";
     }
 
+    public static String getDeviceName(Context ctx) {
+        return Settings.Secure.getString(ctx.getContentResolver(), "bluetooth_name");
+    }
+
     public static String getAppVersionString() {
         return "PCAPdroid v" + BuildConfig.VERSION_NAME;
     }

app/src/main/java/com/emanuelef/remote_capture/activities/AboutActivity.java

@@ -20,30 +20,66 @@
 package com.emanuelef.remote_capture.activities;
 
 import android.content.Intent;
+import android.content.res.Resources;
+import android.graphics.Bitmap;
+import android.graphics.Point;
+import android.net.Uri;
 import android.os.Bundle;
+import android.os.Handler;
+import android.os.Looper;
+import android.os.SystemClock;
 import android.text.method.LinkMovementMethod;
+import android.util.TypedValue;
+import android.view.Display;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
+import android.view.WindowManager;
 import android.widget.EditText;
+import android.widget.ImageView;
 import android.widget.LinearLayout;
+import android.widget.ProgressBar;
 import android.widget.TextView;
+import android.widget.Toast;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
 import androidx.appcompat.app.AlertDialog;
 import androidx.core.content.ContextCompat;
 import androidx.core.text.HtmlCompat;
 import androidx.core.view.MenuProvider;
 
 import com.emanuelef.remote_capture.Billing;
+import com.emanuelef.remote_capture.Log;
 import com.emanuelef.remote_capture.R;
 import com.emanuelef.remote_capture.Utils;
 import com.emanuelef.remote_capture.model.Prefs;
 
+import java.io.BufferedOutputStream;
+import java.io.BufferedReader;
+import java.io.EOFException;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.net.URL;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import javax.net.ssl.HttpsURLConnection;
+
+import androidmads.library.qrgenearator.QRGContents;
+import androidmads.library.qrgenearator.QRGEncoder;
+
 public class AboutActivity extends BaseActivity implements MenuProvider {
     private static final String TAG = "AboutActivity";
+    private ExecutorService mQrReqExecutor;
+    private HttpsURLConnection mQrCon;
+    private boolean mDialogClosing = false;
+    private long mQrStartTime = 0;
+    private long mQrDeadline = 0;
+    private Handler mHandler;
+    private AlertDialog mLicenseDialog;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
@@ -52,6 +88,7 @@ public class AboutActivity extends BaseActivity implements MenuProvider {
         setContentView(R.layout.about_activity);
         addMenuProvider(this);
 
+        mHandler = new Handler(Looper.getMainLooper());
         TextView appVersion = findViewById(R.id.app_version);
         appVersion.setText("PCAPdroid " + Utils.getAppVersion(this));
 
@@ -64,6 +101,25 @@ public class AboutActivity extends BaseActivity implements MenuProvider {
         sourceLink.setMovementMethod(LinkMovementMethod.getInstance());
     }
 
+    @Override
+    protected void onStop() {
+        stopQrExecutor();
+        super.onStop();
+    }
+
+    private void stopQrExecutor() {
+        // necessary to interrupt the executor thread
+        if(mQrCon != null)
+            mQrCon.disconnect();
+        mQrCon = null;
+
+        if(mQrReqExecutor != null)
+            mQrReqExecutor.shutdownNow();
+        mQrReqExecutor = null;
+
+        mHandler.removeCallbacksAndMessages(null);
+    }
+
     @Override
     public void onCreateMenu(@NonNull Menu menu, MenuInflater inflater) {
         inflater.inflate(R.menu.about_menu, menu);
@@ -107,13 +163,20 @@ public class AboutActivity extends BaseActivity implements MenuProvider {
     private void showLicenseDialog() {
         Billing billing = Billing.newInstance(this);
         LayoutInflater inflater = getLayoutInflater();
-        View content = inflater.inflate(R.layout.license_dialog, null);
+        final View content = inflater.inflate(R.layout.license_dialog, null);
 
         String instId = billing.getInstallationId();
         TextView instIdText = content.findViewById(R.id.installation_id);
         instIdText.setText(instId);
-        if(Utils.isTv(this))
+
+        mDialogClosing = false;
+        final View showQr = content.findViewById(R.id.show_qr_code);
+        showQr.setOnClickListener(v -> showQrCode(content, instId));
+
+        if(Utils.isTv(this) && !billing.isPurchased(Billing.SUPPORTER_SKU)) {
             instIdText.setOnClickListener(v -> Utils.shareText(this, getString(R.string.installation_id), instId));
+            showQrCode(content, instId);
+        }
 
         TextView validationRc = content.findViewById(R.id.validation_rc);
         EditText licenseCode = content.findViewById(R.id.license_code);
@@ -122,25 +185,208 @@ public class AboutActivity extends BaseActivity implements MenuProvider {
 
         content.findViewById(R.id.copy_id).setOnClickListener(v -> Utils.copyToClipboard(this, instId));
 
-        boolean was_valid = billing.isPurchased(Billing.SUPPORTER_SKU);
-
-        AlertDialog myDialog = new AlertDialog.Builder(this)
+        mLicenseDialog = new AlertDialog.Builder(this)
                 .setView(content)
                 .setPositiveButton(R.string.ok, (dialog, whichButton) -> {
+                    boolean was_valid = billing.isPurchased(Billing.SUPPORTER_SKU);
                     billing.setLicense(licenseCode.getText().toString());
 
                     if(!was_valid && billing.isPurchased(Billing.SUPPORTER_SKU))
                         Utils.showToastLong(this, R.string.paid_features_unlocked);
                 })
+                .setOnDismissListener(dialog -> {
+                    mDialogClosing = true;
+                    mLicenseDialog = null;
+                    stopQrExecutor();
+                })
                 .setNeutralButton(R.string.validate, (dialog, which) -> {}) // see below
                 .create();
 
-        myDialog.show();
-        myDialog.getButton(AlertDialog.BUTTON_NEUTRAL).setOnClickListener(v -> {
+        mLicenseDialog.show();
+        mLicenseDialog.getButton(AlertDialog.BUTTON_NEUTRAL).setOnClickListener(v -> {
             boolean valid = billing.isValidLicense(licenseCode.getText().toString());
             validationRc.setText(valid ? R.string.valid : R.string.invalid);
             validationRc.setTextColor(ContextCompat.getColor(this, valid ? R.color.ok : R.color.danger));
         });
-        myDialog.getWindow().setLayout(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
+        mLicenseDialog.getWindow().setLayout(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.WRAP_CONTENT);
+    }
+
+    private void showQrCode(View dialog, String instId) {
+        View qrBox = dialog.findViewById(R.id.qr_box);
+        View qrLoading = dialog.findViewById(R.id.qr_code_loading);
+        View showQr = dialog.findViewById(R.id.show_qr_code);
+        View qrInfo = dialog.findViewById(R.id.qr_info_text);
+
+        showQr.setVisibility(View.GONE);
+        qrLoading.setVisibility(View.VISIBLE);
+        qrBox.setVisibility(View.GONE);
+        qrInfo.setVisibility(View.GONE);
+
+        mQrReqExecutor = Executors.newSingleThreadExecutor();
+        Handler handler = new Handler(Looper.getMainLooper());
+
+        // start activation
+        mQrReqExecutor.execute(() -> {
+            try {
+                URL url = new URL(Utils.PCAPDROID_WEBSITE + "/getlicense/qr_activation");
+                HttpsURLConnection con = (HttpsURLConnection) url.openConnection();
+                mQrCon = con;
+
+                try {
+                    con.setRequestProperty("User-Agent", Utils.getAppVersionString());
+                    con.setRequestMethod("POST");
+                    con.setUseCaches(false);
+                    con.setAllowUserInteraction(false);
+                    con.setDoInput(true);
+                    con.setDoOutput(true);
+                    con.setConnectTimeout(5000);
+
+                    // Send POST request
+                    try (BufferedOutputStream os = new BufferedOutputStream(con.getOutputStream())) {
+                        os.write(("installation_id=" + instId).getBytes());
+                    }
+
+                    int rc = con.getResponseCode();
+                    Log.d(TAG, "QR HTTP response: " + rc);
+                    if (rc != 200) {
+                        handler.post(() ->
+                                hideQrCode(dialog, "QR request failed with code " + rc));
+                        return;
+                    }
+
+                    try (BufferedReader reader = new BufferedReader(new InputStreamReader(con.getInputStream()))) {
+                        // Step 1: get QR request ID
+                        String timeout_s = parseSseLine(reader.readLine());
+                        String qr_req_id = parseSseLine(reader.readLine());
+                        if ((qr_req_id == null) || (timeout_s == null)) {
+                            handler.post(() ->
+                                    hideQrCode(dialog, "Invalid QR request ID"));
+                            return;
+                        }
+                        int timeout_ms = Integer.parseInt(timeout_s) * 1000;
+                        long deadline = SystemClock.uptimeMillis() + timeout_ms;
+                        Log.d(TAG, "QR request_id=" + qr_req_id + ", timeout=" + timeout_ms + " ms");
+
+                        // Step 2: generate QR code
+                        Bitmap qrBitmap = genQrCode(instId, qr_req_id);
+                        handler.post(() -> onQrRequestReady(dialog, qrBitmap, deadline));
+
+                        // Step 3: wait license
+                        String license = parseSseLine(reader.readLine());
+                        if(license == null) {
+                            handler.post(() ->
+                                hideQrCode(dialog, getString(R.string.qr_code_expired)));
+                            return;
+                        }
+                        handler.post(() -> onQrLicenseReceived(dialog, license));
+                    }
+                } finally {
+                    con.disconnect();
+                }
+            } catch (IOException | NumberFormatException e) {
+                e.printStackTrace();
+
+                handler.post(() -> {
+                    if(e instanceof EOFException)
+                        hideQrCode(dialog, getString(R.string.qr_code_expired));
+                    else
+                        hideQrCode(dialog, getString(R.string.connection_error, e.getMessage()));
+                });
+            }
+        });
+    }
+
+    private String parseSseLine(String line) {
+        if(line == null)
+            return null;
+
+        if(line.startsWith("data: "))
+            line = line.substring(6);
+        return line;
+    }
+
+    private Bitmap genQrCode(String instId, String qrReqId) {
+        float maxDp = 180f;
+        int maxPx = (int) TypedValue.applyDimension(
+                TypedValue.COMPLEX_UNIT_DIP,
+                maxDp,
+                getResources().getDisplayMetrics()
+        );
+
+        WindowManager manager = (WindowManager) getSystemService(WINDOW_SERVICE);
+        Display display = manager.getDefaultDisplay();
+        Point point = new Point();
+        display.getSize(point);
+        int smallerDimension = Math.min(Math.min(point.x, point.y) / 2, maxPx);
+
+        String qrData = "pcapdroid://get_license?installation_id="+ instId +"&qr_request_id=" + qrReqId + "&device=" + Uri.encode(Utils.getDeviceName(this));
+        Log.d(TAG, "QR activation URI: " + qrData);
+
+        QRGEncoder qrgEncoder = new QRGEncoder(qrData, null, QRGContents.Type.TEXT, smallerDimension);
+        return qrgEncoder.getBitmap(0);
+    }
+
+    private void onQrRequestReady(View dialog, Bitmap qrcode, long deadline) {
+        View qrBox = dialog.findViewById(R.id.qr_box);
+        ImageView qrImage = dialog.findViewById(R.id.qr_code);
+        View qrLoading = dialog.findViewById(R.id.qr_code_loading);
+        View qrInfo = dialog.findViewById(R.id.qr_info_text);
+
+        mQrStartTime = SystemClock.uptimeMillis();
+        mQrDeadline = deadline;
+        updateQrProgress(dialog);
+
+        qrImage.setImageBitmap(qrcode);
+        qrBox.setVisibility(View.VISIBLE);
+        qrInfo.setVisibility(View.VISIBLE);
+        qrLoading.setVisibility(View.GONE);
+    }
+
+    private void updateQrProgress(View dialog) {
+        ProgressBar qrProgress = dialog.findViewById(R.id.qr_remaining_time);
+        if(qrProgress == null)
+            return;
+
+        long interval = mQrDeadline - mQrStartTime;
+        int progress = Math.min((int)((SystemClock.uptimeMillis() - mQrStartTime) * 100 / interval), 100);
+        qrProgress.setProgress(100 - progress);
+
+        mHandler.postDelayed(() -> updateQrProgress(dialog), 1000);
+    }
+
+    private void onQrLicenseReceived(View dialog, String license) {
+        EditText licenseCode = dialog.findViewById(R.id.license_code);
+        Billing billing = Billing.newInstance(this);
+        boolean was_valid = billing.isPurchased(Billing.SUPPORTER_SKU);
+
+        if(billing.setLicense(license)) {
+            licenseCode.setText(license);
+
+            Utils.showToast(this, R.string.license_activation_ok);
+            if(!was_valid)
+                Utils.showToastLong(this, R.string.paid_features_unlocked);
+
+            hideQrCode(dialog, null);
+            if(mLicenseDialog != null)
+                mLicenseDialog.dismiss();
+        } else
+            hideQrCode(dialog, getString(R.string.invalid_license));
+    }
+
+    private void hideQrCode(View dialog, @Nullable String error_msg) {
+        View showQr = dialog.findViewById(R.id.show_qr_code);
+        View qrLoading = dialog.findViewById(R.id.qr_code_loading);
+        View qrBox = dialog.findViewById(R.id.qr_box);
+        View qrInfo = dialog.findViewById(R.id.qr_info_text);
+
+        qrBox.setVisibility(View.GONE);
+        qrInfo.setVisibility(View.GONE);
+        qrLoading.setVisibility(View.GONE);
+        showQr.setVisibility(View.VISIBLE);
+
+        if((error_msg != null) && !mDialogClosing)
+            Toast.makeText(this, error_msg, Toast.LENGTH_LONG).show();
+
+        stopQrExecutor();
     }
 }

app/src/main/res/layout/license_dialog.xml

@@ -1,70 +1,131 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<ScrollView
+    xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
-    android:orientation="vertical"
-    android:layout_width="match_parent"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="wrap_content"
     android:layout_height="wrap_content"
-    android:padding="10dp">
-
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_gravity="center_horizontal"
-        android:textStyle="bold"
-        android:text="@string/installation_id" />
+    android:orientation="vertical">
 
     <LinearLayout
+        android:orientation="vertical"
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:orientation="horizontal"
-        android:gravity="center">
+        android:padding="10dp">
 
         <TextView
-            android:id="@+id/installation_id"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:textIsSelectable="true"
-            android:focusable="true"
-            tools:text="A127ADC1245" />
+            android:layout_gravity="center_horizontal"
+            android:textStyle="bold"
+            android:text="@string/installation_id" />
 
-        <ImageView
-            android:id="@+id/copy_id"
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center">
+
+            <TextView
+                android:id="@+id/installation_id"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:textIsSelectable="true"
+                android:focusable="true"
+                tools:text="A127ADC1245" />
+
+            <ImageView
+                android:id="@+id/copy_id"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginStart="8dp"
+                android:src="@drawable/ic_content_copy" />
+        </LinearLayout>
+
+        <com.google.android.material.button.MaterialButton
+            android:id="@+id/show_qr_code"
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:layout_marginStart="8dp"
-            android:src="@drawable/ic_content_copy" />
+            android:text="@string/activate_via_qr_code"
+            android:layout_gravity="center"
+            style="?attr/materialButtonOutlinedStyle" />
+
+        <TextView
+            android:id="@+id/qr_code_loading"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center"
+            android:visibility="gone"
+            android:text="@string/loading" />
+
+        <TextView
+            android:id="@+id/qr_info_text"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center"
+            android:textAlignment="center"
+            android:visibility="gone"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            android:layout_marginHorizontal="40dp"
+            android:layout_marginTop="10dp"
+            android:text="@string/qr_info_text" />
+
+        <LinearLayout
+            android:id="@+id/qr_box"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:visibility="gone"
+            tools:visibility="visible"
+            android:layout_gravity="center"
+            android:orientation="vertical">
+
+            <ImageView
+                android:id="@+id/qr_code"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginVertical="20dp"
+                tools:layout_width="200dp"
+                tools:layout_height="200dp"/>
+
+            <ProgressBar
+                android:id="@+id/qr_remaining_time"
+                style="@android:style/Widget.Material.ProgressBar.Horizontal"
+                tools:progress="25"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content"/>
+        </LinearLayout>
+
+        <TextView
+            android:id="@+id/paid_features_msg"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginVertical="10dp"
+            android:text="@string/access_paid_features_msg" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:textStyle="bold"
+            android:text="@string/license_code" />
+
+        <EditText
+            android:id="@+id/license_code"
+            android:fontFamily="monospace"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:inputType="textMultiLine"
+            android:gravity="top"
+            android:lines="4" />
+
+        <TextView
+            android:id="@+id/validation_rc"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:textColor="@color/ok"
+            android:textAllCaps="true"
+            android:textSize="13sp"
+            tools:text="@string/valid" />
     </LinearLayout>
-
-    <TextView
-        android:id="@+id/paid_features_msg"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginTop="20dp"
-        android:text="@string/access_paid_features_msg" />
-
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginTop="10dp"
-        android:textStyle="bold"
-        android:text="@string/license_code" />
-
-    <EditText
-        android:id="@+id/license_code"
-        android:fontFamily="monospace"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:inputType="textMultiLine"
-        android:gravity="top"
-        android:lines="4" />
-
-    <TextView
-        android:id="@+id/validation_rc"
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:textColor="@color/ok"
-        android:textAllCaps="true"
-        android:textSize="13sp"
-        tools:text="@string/valid" />
-
-</LinearLayout>
+</ScrollView>

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

@@ -26,6 +26,7 @@
         - FlagKit: <a href='https://github.com/madebybowtie/FlagKit/blob/master/LICENSE'>MIT</a>\n\n
         - IP Geolocation by <a href='https://db-ip.com'>DB-IP</a>\n\n
         - AppIntro: <a href='https://github.com/AppIntro/AppIntro/blob/main/LICENSE'>Apache-2.0</a>\n\n
+        - QrGenerator: <a href='https://github.com/androidmads/QRGenerator/blob/master/LICENSE.md'>MIT</a>\n\n
         - Font Awesome: <a href='https://fontawesome.com/license/free'>Licenses</a>\n\n
         - App icon by <a href="https://www.freepik.com" title="Freepik">Freepik</a> from <a href="https://www.flaticon.com/" title="Flaticon">flaticon</a>\n\n
         - SourceCodePro font: <a href='https://github.com/adobe-fonts/source-code-pro/blob/release/LICENSE.md'>OFL-1.1</a>\n\n
@@ -461,4 +462,15 @@
     <string name="username">Username</string>
     <string name="password">Password</string>
     <string name="mitm_addon_autostart_workaround">Connection to the mitm addon failed. As a workaround, you can try to open the mitm addon app and then go back to PCAPdroid without closing it. Do you want to open it now?</string>
+    <string name="qr_license_confirm">Do you want to generate a license for the \"%1$s\" device using the following unlock token?</string>
+    <string name="invalid_license">Invalid license</string>
+    <string name="connection_error">Connection error: %1$s</string>
+    <string name="activate_via_qr_code">Activate via QR code</string>
+    <string name="qr_code_expired">QR code expired. Generate a new QR code and retry</string>
+    <string name="qr_info_text">Install PCAPdroid from Google Play and scan this QR code</string>
+    <string name="qr_purchase_required">Purchase an unlock token to proceed with the QR code activation</string>
+    <string name="license_limit_reached">You have reached the licenses limit for this unlock token. Buy a new token to generate more licenses</string>
+    <string name="license_error">License generation error [%1$d]: %2$s</string>
+    <string name="requesting_license">Requesting a license code, please wait</string>
+    <string name="license_activation_ok">License activation completed</string>
 </resources>