Allow capturing multiple target apps

The target app option has been extended to allow the selection
of multiple apps.

Closes #146

app/src/main/AndroidManifest.xml

@@ -110,6 +110,10 @@
         <activity
             android:name=".activities.MitmSetupWizard"
             android:launchMode="singleTop" />
+        <activity
+            android:name=".activities.AppFilterActivity"
+            android:launchMode="singleTop"
+            android:parentActivityName=".activities.MainActivity" />
 
         <service
             android:name=".CaptureService"

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

@@ -86,6 +86,7 @@ import java.net.InetSocketAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
 import java.net.UnknownHostException;
+import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.HashSet;
 import java.util.Iterator;
@@ -127,7 +128,7 @@ public class CaptureService extends VpnService implements Runnable {
     private String dns_server;
     private long last_bytes;
     private int last_connections;
-    private int app_filter_uid;
+    private int[] mAppFilterUids;
     private PcapDumper mDumper;
     private ConnectionsRegister conn_reg;
     private Uri mPcapUri;
@@ -269,7 +270,7 @@ public class CaptureService extends VpnService implements Runnable {
         if(mSettings.readFromPcap()) {
             // Disable incompatible settings
             mSettings.dump_mode = Prefs.DumpMode.NONE;
-            mSettings.app_filter = "";
+            mSettings.app_filter.clear();
             mSettings.socks5_enabled = false;
             mSettings.tls_decryption = false;
             mSettings.root_capture = false;
@@ -406,14 +407,29 @@ public class CaptureService extends VpnService implements Runnable {
             mDecryptionList = null;
 
         if ((mSettings.app_filter != null) && (!mSettings.app_filter.isEmpty())) {
-            try {
-                app_filter_uid = Utils.getPackageUid(getPackageManager(), mSettings.app_filter, 0);
-            } catch (PackageManager.NameNotFoundException e) {
-                e.printStackTrace();
-                app_filter_uid = -1;
+            ArrayList<Integer> uids = new ArrayList<>();
+
+            for (String package_name: mSettings.app_filter) {
+                int uid;
+
+                try {
+                    uid = Utils.getPackageUid(getPackageManager(), package_name, 0);
+                } catch (PackageManager.NameNotFoundException e) {
+                    e.printStackTrace();
+                    continue;
+                }
+
+                uids.add(uid);
             }
+
+            // populate the array only with resolved UIDs
+            mAppFilterUids = new int[uids.size()];
+
+            int i = 0;
+            for (Integer uid: uids)
+                mAppFilterUids[i++] = uid;
         } else
-            app_filter_uid = -1;
+            mAppFilterUids = new int[0];
 
         mMalwareDetectionEnabled = Prefs.isMalwareDetectionEnabled(this, mPrefs);
         mFirewallEnabled = Prefs.isFirewallEnabled(this, mPrefs);
@@ -458,7 +474,8 @@ public class CaptureService extends VpnService implements Runnable {
                     // NOTE: the API requires a package name, however it is converted to a UID
                     // (see Vpn.java addUserToRanges). This means that vpn routing happens on a UID basis,
                     // not on a package-name basis!
-                    builder.addAllowedApplication(mSettings.app_filter);
+                    for (String package_name: mSettings.app_filter)
+                        builder.addAllowedApplication(package_name);
                 } catch (PackageManager.NameNotFoundException e) {
                     String msg = String.format(getResources().getString(R.string.app_not_found), mSettings.app_filter);
                     Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
@@ -958,7 +975,7 @@ public class CaptureService extends VpnService implements Runnable {
         return rv;
     }
 
-    public static String getAppFilter() {
+    public static Set<String> getAppFilter() {
         return((INSTANCE != null) ? INSTANCE.mSettings.app_filter : null);
     }
 
@@ -1291,7 +1308,7 @@ public class CaptureService extends VpnService implements Runnable {
 
     public int isPcapngEnabled() { return(mSettings.pcapng_format ? 1 : 0); }
 
-    public int getAppFilterUid() { return(app_filter_uid); }
+    public int[] getAppFilterUids() { return(mAppFilterUids); }
 
     public int getMitmAddonUid() {
         return MitmAddon.getUid(this);

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

@@ -0,0 +1,142 @@
+package com.emanuelef.remote_capture.activities;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.os.Build;
+import android.os.Bundle;
+import android.view.Menu;
+import android.view.MenuInflater;
+import android.view.MenuItem;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.core.view.MenuProvider;
+import androidx.preference.PreferenceManager;
+
+import com.emanuelef.remote_capture.Log;
+import com.emanuelef.remote_capture.R;
+import com.emanuelef.remote_capture.Utils;
+import com.emanuelef.remote_capture.fragments.AppsToggles;
+import com.emanuelef.remote_capture.model.AppDescriptor;
+import com.emanuelef.remote_capture.model.Prefs;
+
+import java.util.HashSet;
+import java.util.Set;
+
+public class AppFilterActivity extends BaseActivity implements MenuProvider {
+    private static final String TAG = "AppFilterActivity";
+    private AppFilterFragment mFragment;
+
+    @Override
+    @SuppressWarnings("deprecation")
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setTitle(R.string.target_apps);
+        setContentView(R.layout.fragment_activity);
+        addMenuProvider(this);
+        displayBackAction();
+
+        if (savedInstanceState != null)
+            mFragment = (AppFilterFragment) getSupportFragmentManager().getFragment(savedInstanceState, "fragment");
+        if (mFragment == null)
+            mFragment = new AppFilterFragment();
+
+        getSupportFragmentManager().beginTransaction()
+                .replace(R.id.fragment, mFragment)
+                .commit();
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
+            overrideActivityTransition(OVERRIDE_TRANSITION_OPEN, 0, 0);
+        else
+            overridePendingTransition(0, 0);
+    }
+
+    @Override
+    protected void onSaveInstanceState(@NonNull Bundle outState) {
+        super.onSaveInstanceState(outState);
+        getSupportFragmentManager().putFragment(outState, "fragment", mFragment);
+    }
+
+    @Override
+    public void onCreateMenu(@NonNull Menu menu, MenuInflater inflater) {
+        inflater.inflate(R.menu.hint_menu, menu);
+    }
+
+    @Override
+    public boolean onMenuItemSelected(@NonNull MenuItem item) {
+        int id = item.getItemId();
+
+        if (id == R.id.show_hint) {
+            Utils.showHelpDialog(this, R.string.target_apps_help);
+            return true;
+        }
+
+        return false;
+    }
+
+    @Override
+    @SuppressWarnings("deprecation")
+    public void onBackPressed() {
+        if(mFragment.onBackPressed())
+            return;
+
+        super.onBackPressed();
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
+            overrideActivityTransition(OVERRIDE_TRANSITION_CLOSE, 0, 0);
+        else
+            overridePendingTransition(0, 0);
+    }
+
+    public static class AppFilterFragment extends AppsToggles {
+        private final Set<String> mSelectedApps = new HashSet<>();
+        private @Nullable SharedPreferences mPrefs;
+
+        @Override
+        public void onAttach(@NonNull Context context) {
+            super.onAttach(context);
+            mPrefs = PreferenceManager.getDefaultSharedPreferences(context);
+            assert mPrefs != null;
+
+            mSelectedApps.clear();
+
+            Set<String> saved = Prefs.getStringSet(mPrefs, Prefs.PREF_APP_FILTER);
+            if(!saved.isEmpty()) {
+                Log.d(TAG, "Loading " + saved.size() + " target apps");
+                mSelectedApps.addAll(saved);
+            }
+        }
+
+        @Override
+        public void onDetach() {
+            super.onDetach();
+            mPrefs = null;
+        }
+
+        @Override
+        protected Set<String> getCheckedApps() {
+            return mSelectedApps;
+        }
+
+        @Override
+        public void onAppToggled(AppDescriptor app, boolean checked) {
+            String packageName = app.getPackageName();
+            if(mSelectedApps.contains(packageName) == checked)
+                return; // nothing to do
+
+            if(checked)
+                mSelectedApps.add(packageName);
+            else
+                mSelectedApps.remove(packageName);
+
+            Log.d(TAG, "Saving " + mSelectedApps.size() + " target apps");
+
+            if(mPrefs == null)
+                return;
+
+            mPrefs.edit()
+                    .putStringSet(Prefs.PREF_APP_FILTER, mSelectedApps)
+                    .apply();
+        }
+    }
+}

app/src/main/java/com/emanuelef/remote_capture/activities/prefs/VpnExemptionsActivity.java

@@ -46,6 +46,7 @@ public class VpnExemptionsActivity extends BaseActivity {
         super.onCreate(savedInstanceState);
         setTitle(R.string.vpn_exemptions);
         setContentView(R.layout.fragment_activity);
+        displayBackAction();
 
         if(savedInstanceState != null)
             mFragment = (VpnExceptionsFragment) getSupportFragmentManager().getFragment(savedInstanceState, "fragment");
@@ -63,15 +64,6 @@ public class VpnExemptionsActivity extends BaseActivity {
         getSupportFragmentManager().putFragment(outState, "fragment", mFragment);
     }
 
-    @Override
-    public boolean onOptionsItemSelected(@NonNull MenuItem item) {
-        if(item.getItemId() == android.R.id.home) {
-            onBackPressed();
-            return true;
-        }
-        return super.onOptionsItemSelected(item);
-    }
-
     @Override
     @SuppressWarnings("deprecation")
     public void onBackPressed() {

app/src/main/java/com/emanuelef/remote_capture/fragments/StatusFragment.java

@@ -14,19 +14,21 @@
  * You should have received a copy of the GNU General Public License
  * along with PCAPdroid.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Copyright 2020-21 - Emanuele Faranda
+ * Copyright 2020-24 - Emanuele Faranda
  */
 
 package com.emanuelef.remote_capture.fragments;
 
 import android.annotation.SuppressLint;
 import android.content.Context;
+import android.content.Intent;
 import android.content.SharedPreferences;
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Looper;
 import android.text.method.LinkMovementMethod;
+import android.util.Pair;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -38,8 +40,8 @@ import android.widget.TextView;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
-import androidx.appcompat.app.AppCompatActivity;
 import androidx.appcompat.widget.SwitchCompat;
+import androidx.core.content.ContextCompat;
 import androidx.core.view.MenuProvider;
 import androidx.fragment.app.Fragment;
 import androidx.lifecycle.Lifecycle;
@@ -48,6 +50,7 @@ import androidx.preference.PreferenceManager;
 import com.emanuelef.remote_capture.AppsResolver;
 import com.emanuelef.remote_capture.Log;
 import com.emanuelef.remote_capture.MitmReceiver;
+import com.emanuelef.remote_capture.activities.AppFilterActivity;
 import com.emanuelef.remote_capture.model.AppDescriptor;
 import com.emanuelef.remote_capture.model.AppState;
 import com.emanuelef.remote_capture.CaptureService;
@@ -57,9 +60,11 @@ import com.emanuelef.remote_capture.activities.MainActivity;
 import com.emanuelef.remote_capture.interfaces.AppStateListener;
 import com.emanuelef.remote_capture.model.Prefs;
 import com.emanuelef.remote_capture.model.CaptureStats;
-import com.emanuelef.remote_capture.views.AppSelectDialog;
 import com.emanuelef.remote_capture.views.PrefSpinner;
 
+import java.util.ArrayList;
+import java.util.Set;
+
 public class StatusFragment extends Fragment implements AppStateListener, MenuProvider {
     private static final String TAG = "StatusFragment";
     private Handler mHandler;
@@ -75,9 +80,8 @@ public class StatusFragment extends Fragment implements AppStateListener, MenuPr
     private SharedPreferences mPrefs;
     private TextView mFilterDescription;
     private SwitchCompat mAppFilterSwitch;
-    private String mAppFilter;
+    private Set<String> mAppFilter;
     private TextView mFilterRootDecryptionWarning;
-    private AppSelectDialog mAppSelDialog;
 
     @Override
     public void onAttach(@NonNull Context context) {
@@ -88,7 +92,6 @@ public class StatusFragment extends Fragment implements AppStateListener, MenuPr
     @Override
     public void onDetach() {
         super.onDetach();
-        abortAppSelection();
         mActivity.setAppStateListener(null);
         mActivity = null;
     }
@@ -145,14 +148,11 @@ public class StatusFragment extends Fragment implements AppStateListener, MenuPr
             });
         }
 
-        filterTitle.setText(R.string.app_filter);
+        filterTitle.setText(R.string.target_apps);
 
-        mAppFilterSwitch.setOnCheckedChangeListener((buttonView, isChecked) -> {
-            if(isChecked) {
-                if((mAppFilter == null) || (mAppFilter.isEmpty()))
-                    openAppFilterSelector();
-            } else
-                setAppFilter(null);
+        mAppFilterSwitch.setOnClickListener((buttonView) -> {
+            mAppFilterSwitch.setChecked(!mAppFilterSwitch.isChecked());
+            openAppFilterSelector();
         });
 
         refreshFilterInfo();
@@ -222,34 +222,20 @@ public class StatusFragment extends Fragment implements AppStateListener, MenuPr
 
         mAppFilterSwitch.setChecked(true);
 
-        AppDescriptor app = AppsResolver.resolveInstalledApp(context.getPackageManager(), mAppFilter, 0);
-        String description;
+        Pair<String, Drawable> pair = getAppFilterTextAndIcon(context);
 
-        if(app == null)
-            description = mAppFilter;
-        else {
-            description = app.getName() + " (" + app.getPackageName() + ")";
+        mFilterDescription.setText(pair.first);
+
+        if (pair.second != null) {
             int height = mFilterDescription.getMeasuredHeight();
 
-            if((height > 0) && (app.getIcon() != null)) {
-                Drawable drawable = Utils.scaleDrawable(context.getResources(), app.getIcon(), height, height);
+            if(height > 0) {
+                Drawable drawable = Utils.scaleDrawable(context.getResources(), pair.second, height, height);
 
                 if(drawable != null)
                     mFilterDescription.setCompoundDrawablesWithIntrinsicBounds(drawable, null, null, null);
             }
         }
-
-        mFilterDescription.setText(description);
-    }
-
-    private void setAppFilter(AppDescriptor filter) {
-        SharedPreferences.Editor editor = mPrefs.edit();
-        mAppFilter = (filter != null) ? filter.getPackageName() : "";
-
-        editor.putString(Prefs.PREF_APP_FILTER, mAppFilter);
-        editor.apply();
-        refreshFilterInfo();
-        recheckFilterWarning();
     }
 
     private void onStatsUpdate(CaptureStats stats) {
@@ -259,6 +245,42 @@ public class StatusFragment extends Fragment implements AppStateListener, MenuPr
         mCaptureStatus.setText(Utils.formatBytes(stats.bytes_sent + stats.bytes_rcvd));
     }
 
+    private Pair<String, Drawable> getAppFilterTextAndIcon(@NonNull Context context) {
+        Drawable icon = null;
+        String text = "";
+
+        if((mAppFilter != null) && (!mAppFilter.isEmpty())) {
+            if (mAppFilter.size() == 1) {
+                // only a single app is selected, show its image and text
+                String package_name = mAppFilter.iterator().next();
+                AppDescriptor app = AppsResolver.resolveInstalledApp(requireContext().getPackageManager(), package_name, 0);
+
+                if((app != null) && (app.getIcon() != null)) {
+                    icon = app.getIcon();
+                    text = app.getName() + " (" + app.getPackageName() + ")";
+                }
+            } else {
+                // multiple apps, show default icon and comprehensive text
+                icon = ContextCompat.getDrawable(context, R.drawable.ic_image);
+                ArrayList<String> parts = new ArrayList<>();
+
+                for (String package_name: mAppFilter) {
+                    AppDescriptor app = AppsResolver.resolveInstalledApp(requireContext().getPackageManager(), package_name, 0);
+                    String tmp = package_name;
+
+                    if (app != null)
+                        tmp = app.getName();
+
+                    parts.add(tmp);
+                }
+
+                text = Utils.shorten(String.join(", ", parts), 48);
+            }
+        }
+
+        return new Pair<>(text, icon);
+    }
+
     private void refreshPcapDumpInfo() {
         String info = "";
 
@@ -287,26 +309,29 @@ public class StatusFragment extends Fragment implements AppStateListener, MenuPr
 
         mCollectorInfo.setText(info);
 
-        // Check if a filter is set
-        if((mAppFilter != null) && (!mAppFilter.isEmpty())) {
-            AppDescriptor app = AppsResolver.resolveInstalledApp(requireContext().getPackageManager(), mAppFilter, 0);
+        // Rendering after mCollectorInfo.setText is deferred, so getMeasuredHeight must be postponed
+        mHandler.post(() -> {
+            Context context = getContext();
+            if(context == null)
+                return;
 
-            if((app != null) && (app.getIcon() != null)) {
-                // Rendering after mCollectorInfo.setText is deferred, so getMeasuredHeight must be postponed
-                mHandler.post(() -> {
-                    if(getContext() == null)
-                        return;
+            // Check if a filter is set
+            if((mAppFilter != null) && (!mAppFilter.isEmpty())) {
+                Pair<String, Drawable> pair = getAppFilterTextAndIcon(context);
 
+                if (pair.second != null) {
+                    // scale and set
                     int height = mCollectorInfo.getMeasuredHeight();
-                    Drawable drawable = Utils.scaleDrawable(getResources(), app.getIcon(), height, height);
+                    Drawable drawable = Utils.scaleDrawable(getResources(), pair.second, height, height);
 
-                    if(drawable != null)
+                    if (drawable != null)
                         mCollectorInfo.setCompoundDrawablesWithIntrinsicBounds(null, null, drawable, null);
-                });
-            } else
-                mCollectorInfo.setCompoundDrawablesWithIntrinsicBounds(null, null, null, null);
-        } else
-            mCollectorInfo.setCompoundDrawablesWithIntrinsicBounds(null, null, null, null);
+                }
+            }
+        });
+
+        // will be overriden in the above handler if necessary
+        mCollectorInfo.setCompoundDrawablesWithIntrinsicBounds(null, null, null, null);
     }
 
     @Override
@@ -386,26 +411,7 @@ public class StatusFragment extends Fragment implements AppStateListener, MenuPr
     }
 
     private void openAppFilterSelector() {
-        mAppSelDialog = new AppSelectDialog((AppCompatActivity) requireActivity(), R.string.app_filter,
-                new AppSelectDialog.AppSelectListener() {
-            @Override
-            public void onSelectedApp(AppDescriptor app) {
-                abortAppSelection();
-                setAppFilter(app);
-            }
-
-            @Override
-            public void onAppSelectionAborted() {
-                abortAppSelection();
-                setAppFilter(null);
-            }
-        });
-    }
-
-    private void abortAppSelection() {
-        if(mAppSelDialog != null) {
-            mAppSelDialog.abort();
-            mAppSelDialog = null;
-        }
+        Intent intent = new Intent(requireContext(), AppFilterActivity.class);
+        startActivity(intent);
     }
 }

app/src/main/java/com/emanuelef/remote_capture/model/CaptureSettings.java

@@ -8,10 +8,15 @@ import android.os.Bundle;
 import com.emanuelef.remote_capture.Billing;
 
 import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
 
 public class CaptureSettings implements Serializable {
     public Prefs.DumpMode dump_mode;
-    public String app_filter;
+    public Set<String> app_filter;
     public String collector_address;
     public int collector_port;
     public int http_server_port;
@@ -62,7 +67,7 @@ public class CaptureSettings implements Serializable {
 
     public CaptureSettings(Context ctx, Intent intent) {
         dump_mode = Prefs.getDumpMode(getString(intent, "pcap_dump_mode", "none"));
-        app_filter = getString(intent, Prefs.PREF_APP_FILTER, "");
+        app_filter = new HashSet<>(getStringList(intent, Prefs.PREF_APP_FILTER));
         collector_address = getString(intent, Prefs.PREF_COLLECTOR_IP_KEY, "127.0.0.1");
         collector_port = getInt(intent, Prefs.PREF_COLLECTOR_PORT_KEY, 1234);
         http_server_port = getInt(intent, Prefs.PREF_HTTP_SERVER_PORT, 8080);
@@ -113,6 +118,25 @@ public class CaptureSettings implements Serializable {
         return bundle.getBoolean(key, def_value);
     }
 
+    // get a list of comma-separated strings from the bundle
+    private static List<String> getStringList(Intent intent, String key) {
+        List<String> rv;
+
+        String s = intent.getStringExtra(key);
+        if(s != null) {
+            if (s.indexOf(',') < 0) {
+                rv = new ArrayList<>();
+                rv.add(s);
+            } else {
+                String[] arr = s.split(",");
+                rv = Arrays.asList(arr);
+            }
+        } else
+            rv = new ArrayList<>();
+
+        return rv;
+    }
+
     public boolean readFromPcap() {
         return input_pcap_path != null;
     }

app/src/main/java/com/emanuelef/remote_capture/model/Prefs.java

@@ -19,9 +19,11 @@
 
 package com.emanuelef.remote_capture.model;
 
+import android.annotation.SuppressLint;
 import android.content.Context;
 import android.content.SharedPreferences;
 
+import androidx.annotation.NonNull;
 import androidx.preference.PreferenceManager;
 
 import com.emanuelef.remote_capture.Billing;
@@ -29,6 +31,9 @@ import com.emanuelef.remote_capture.BuildConfig;
 import com.emanuelef.remote_capture.MitmAddon;
 import com.emanuelef.remote_capture.Utils;
 
+import java.util.HashSet;
+import java.util.Set;
+
 public class Prefs {
     public static final String DUMP_NONE = "none";
     public static final String DUMP_HTTP_SERVER = "http_server";
@@ -199,7 +204,7 @@ public class Prefs {
     public static boolean isSocks5AuthEnabled(SharedPreferences p)  { return(p.getBoolean(PREF_SOCKS5_AUTH_ENABLED_KEY, false)); }
     public static String getSocks5Username(SharedPreferences p)     { return(p.getString(PREF_SOCKS5_USERNAME_KEY, "")); }
     public static String getSocks5Password(SharedPreferences p)     { return(p.getString(PREF_SOCKS5_PASSWORD_KEY, "")); }
-    public static String getAppFilter(SharedPreferences p)       { return(p.getString(PREF_APP_FILTER, "")); }
+    public static Set<String> getAppFilter(SharedPreferences p)     { return(getStringSet(p, PREF_APP_FILTER)); }
     public static IpMode getIPMode(SharedPreferences p)          { return(getIPMode(p.getString(PREF_IP_MODE, IP_MODE_DEFAULT))); }
     public static BlockQuicMode getBlockQuicMode(SharedPreferences p) { return(getBlockQuicMode(p.getString(PREF_BLOCK_QUIC, BLOCK_QUIC_MODE_DEFAULT))); }
     public static boolean useEnglishLanguage(SharedPreferences p){ return("english".equals(p.getString(PREF_APP_LANGUAGE, "system")));}
@@ -234,6 +239,31 @@ public class Prefs {
     public static String getDnsServerV4(SharedPreferences p)    { return(p.getString(PREF_DNS_SERVER_V4, "1.1.1.1")); }
     public static String getDnsServerV6(SharedPreferences p)    { return(p.getString(PREF_DNS_SERVER_V6, "2606:4700:4700::1111")); }
 
+    // Gets a StringSet from the prefs
+    // The preference should either be a StringSet or a String
+    // An empty set is returned as the default value
+    @SuppressLint("MutatingSharedPrefs")
+    public static @NonNull Set<String> getStringSet(SharedPreferences p, String key) {
+        Set<String> rv = null;
+
+        try {
+            rv = p.getStringSet(key, null);
+        } catch (ClassCastException e) {
+            // retry with string
+            String s = p.getString(key, "");
+
+            if (!s.isEmpty()) {
+                rv = new HashSet<>();
+                rv.add(s);
+            }
+        }
+
+        if (rv == null)
+            rv = new HashSet<>();
+
+        return rv;
+    }
+
     public static String asString(Context ctx) {
         SharedPreferences p = PreferenceManager.getDefaultSharedPreferences(ctx);
 
@@ -252,7 +282,7 @@ public class Prefs {
                 "\nFirewall: " + isFirewallEnabled(ctx, p) +
                 "\nPCAPNG: " + isPcapngEnabled(ctx, p) +
                 "\nBlockNewApps: " + blockNewApps(p) +
-                "\nAppFilter: " + getAppFilter(p) +
+                "\nTargetApps: " + getAppFilter(p) +
                 "\nIpMode: " + getIPMode(p) +
                 "\nTrailer: " + isPcapdroidTrailerEnabled(p) +
                 "\nStartAtBoot: " + startAtBoot(p);

app/src/main/jni/core/capture_libpcap.c

@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with PCAPdroid.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Copyright 2021 - Emanuele Faranda
+ * Copyright 2021-24 - Emanuele Faranda
  */
 
 #include <sys/un.h>
@@ -103,6 +103,25 @@ static bool valid_bpf(const char *bpf) {
 
 /* ******************************************************* */
 
+static const char* get_uids_filter(pcapdroid_t *pd, char *buf, size_t buf_size) {
+    if (pd->tls_decryption.enabled || (pd->pcap.app_filter_uids_size <= 0))
+        return "-1";
+
+    size_t off = 0;
+
+    for (int i = 0; (i < pd->pcap.app_filter_uids_size) && (off < buf_size); i++) {
+        const char * fmt = (i == 0) ? "%d" : ",%d";
+        off += snprintf(buf + off, (buf_size - off), fmt, pd->pcap.app_filter_uids[i]);
+    }
+
+    if (off >= buf_size)
+        log_e("The UID filter has been truncated");
+
+    return buf;
+}
+
+/* ******************************************************* */
+
 static int connectPcapd(pcapdroid_t *pd) {
     int sock;
     int client = -1;
@@ -185,9 +204,11 @@ static int connectPcapd(pcapdroid_t *pd) {
     }
 
     // Start the daemon
+    char uids_filter_buf[128];
     char args[256];
-    snprintf(args, sizeof(args), "-l pcapd.log -L %u -i '%s' -u %d -t -b '%s'%s",
-             getuid(), pd->pcap.capture_interface, pd->tls_decryption.enabled ? -1 : pd->app_filter,
+    snprintf(args, sizeof(args), "-l pcapd.log -L %u -i '%s' -u %s -t -b '%s'%s",
+             getuid(), pd->pcap.capture_interface,
+             get_uids_filter(pd, uids_filter_buf, sizeof(uids_filter_buf)),
              bpf, pd->pcap.daemonize ? " -d" : "");
 
     pid = start_subprocess(pcapd, args, pd->pcap.as_root, NULL);
@@ -271,10 +292,10 @@ cleanup:
 
 /* ******************************************************* */
 
-static char* get_mitm_redirection_args(pcapdroid_t *pd, char *buf, bool add) {
+static char* get_mitm_redirection_args(pcapdroid_t *pd, char *buf, int uid, bool add) {
     int off = sprintf(buf, "-t nat -%c OUTPUT -p tcp -m owner ", add ? 'I' : 'D');
-    if(pd->app_filter >= 0)
-        off += sprintf(buf + off, "--uid-owner %d", pd->app_filter);
+    if(uid >= 0)
+        off += sprintf(buf + off, "--uid-owner %d", uid);
     else
         off += sprintf(buf + off, "! --uid-owner %d", pd->mitm_addon_uid);
     sprintf(buf + off, " -j REDIRECT --to 7780");
@@ -604,6 +625,7 @@ int run_libpcap(pcapdroid_t *pd) {
     char bpf[256];
     bpf[0] = '\0';
 
+    pd->pcap.app_filter_uids_size = getIntArrayPref(pd->env, pd->capture_service, "getAppFilterUids", &pd->pcap.app_filter_uids);
     pd->pcap.as_root = !pd->pcap_file_capture;
     pd->pcap.bpf = getStringPref(pd, "getPcapDumperBpf", bpf, sizeof(bpf));
     pd->pcap.capture_interface = getStringPref(pd, "getCaptureInterface", capture_interface, sizeof(capture_interface));
@@ -628,10 +650,23 @@ int run_libpcap(pcapdroid_t *pd) {
     if(pd->tls_decryption.enabled) {
         char args[128];
 
-        if(run_shell_cmd("iptables", get_mitm_redirection_args(pd, args, true), true, true) != 0)
-            goto cleanup;
+        if(pd->pcap.app_filter_uids_size > 0) {
+            for (int i = 0; i < pd->pcap.app_filter_uids_size; i++) {
+                int uid = pd->pcap.app_filter_uids[i];
 
-        iptables_cleanup = true;
+                if (uid >= 0) {
+                    if(run_shell_cmd("iptables", get_mitm_redirection_args(pd, args, uid, true), true, true) != 0)
+                        goto cleanup;
+
+                    iptables_cleanup = true;
+                }
+            }
+        } else {
+            if(run_shell_cmd("iptables", get_mitm_redirection_args(pd, args, -1, true), true, true) != 0)
+                goto cleanup;
+
+            iptables_cleanup = true;
+        }
     }
 
     pd_refresh_time(pd);
@@ -722,7 +757,16 @@ cleanup:
 
     if(iptables_cleanup) {
         char args[128];
-        run_shell_cmd("iptables", get_mitm_redirection_args(pd, args, false), true, false);
+
+        if(pd->pcap.app_filter_uids_size > 0) {
+            for (int i = 0; i < pd->pcap.app_filter_uids_size; i++) {
+                int uid = pd->pcap.app_filter_uids[i];
+
+                if (uid >= 0)
+                    run_shell_cmd("iptables", get_mitm_redirection_args(pd, args, uid, false), true, false);
+            }
+        } else
+            run_shell_cmd("iptables", get_mitm_redirection_args(pd, args, -1, false), true, false);
     }
 
     if((pd->pcap.pcapd_pid > 0) && !pd->pcap.daemonize) {
@@ -735,5 +779,14 @@ cleanup:
             process_pcapd_rv(pd, WEXITSTATUS(status));
     }
 
+#if ANDROID
+    if (pd->pcap.app_filter_uids) {
+        pd_free(pd->pcap.app_filter_uids);
+
+        pd->pcap.app_filter_uids = NULL;
+        pd->pcap.app_filter_uids_size = 0;
+    }
+#endif
+
     return rv;
 }

app/src/main/jni/core/jni_impl.c

@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with PCAPdroid.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Copyright 2022 - Emanuele Faranda
+ * Copyright 2022-24 - Emanuele Faranda
  */
 
 #if ANDROID
@@ -585,7 +585,6 @@ Java_com_emanuelef_remote_1capture_CaptureService_runPacketLoop(JNIEnv *env, jcl
                     .notify_blacklists_loaded = notifyBlacklistsLoaded,
                     .dump_payload_chunk = dumpPayloadChunk,
             },
-            .app_filter = getIntPref(env, vpn, "getAppFilterUid"),
             .mitm_addon_uid = getIntPref(env, vpn, "getMitmAddonUid"),
             .vpn_capture = (bool) getIntPref(env, vpn, "isVpnCapture"),
             .pcap_file_capture = (bool) getIntPref(env, vpn, "isPcapFileCapture"),
@@ -1213,6 +1212,41 @@ int getIntPref(JNIEnv *env, jobject vpn_inst, const char *key) {
 
 /* ******************************************************* */
 
+// Retrieve a int[] pref.
+// If rv is >0, out points to the allocated array. It's up to the caller to free it with pd_free
+int getIntArrayPref(JNIEnv *env, jobject vpn_inst, const char *key, int **out) {
+    int rv = -1;
+    jmethodID midMethod = jniGetMethodID(env, cls.vpn_service, key, "()[I");
+    jintArray jarr = (jintArray) (*env)->CallObjectMethod(env, vpn_inst, midMethod);
+
+    if (!jniCheckException(env)) {
+        int size = (*env)->GetArrayLength(env, jarr);
+        log_d("getIntArrayPref(%s) = #%d", key, size);
+
+        if (size > 0) {
+            jint *array = (*env)->GetIntArrayElements(env, jarr, NULL);
+            if (array) {
+                size_t arr_size = size * sizeof(int);
+
+                *out = (int*) pd_malloc(arr_size);
+                if (*out) {
+                    // success
+                    memcpy(*out, array, arr_size);
+                    rv = size;
+                }
+
+                (*env)->ReleaseIntArrayElements(env, jarr, array, 0);
+            }
+        } else
+            rv = size;
+    }
+
+    (*env)->DeleteLocalRef(env, jarr);
+    return rv;
+}
+
+/* ******************************************************* */
+
 void getApplicationByUid(pcapdroid_t *pd, jint uid, char *buf, int bufsize) {
     JNIEnv *env = pd->env;
     const char *value = NULL;

app/src/main/jni/core/pcapdroid.c

@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with PCAPdroid.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Copyright 2020-21 - Emanuele Faranda
+ * Copyright 2020-24 - Emanuele Faranda
  */
 
 #include <inttypes.h>

app/src/main/jni/core/pcapdroid.h

@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with PCAPdroid.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Copyright 2020-21 - Emanuele Faranda
+ * Copyright 2020-24 - Emanuele Faranda
  */
 
 #ifndef __PCAPDROID_H__
@@ -195,7 +195,6 @@ typedef struct pcapdroid {
     int filesdir_len;
 
     // config
-    jint app_filter;
     jint mitm_addon_uid;
     bool vpn_capture;
     bool pcap_file_capture;
@@ -233,6 +232,9 @@ typedef struct pcapdroid {
             char *bpf;
             char *capture_interface;
             int pcapd_pid;
+
+            int *app_filter_uids;
+            int app_filter_uids_size;
         } pcap;
     };
 
@@ -406,6 +408,7 @@ uint16_t pd_ndpi2proto(ndpi_protocol proto);
 
 char* getStringPref(pcapdroid_t *pd, const char *key, char *buf, int bufsize);
 int getIntPref(JNIEnv *env, jobject vpn_inst, const char *key);
+int getIntArrayPref(JNIEnv *env, jobject vpn_inst, const char *key, int **out);
 zdtun_ip_t getIPPref(JNIEnv *env, jobject vpn_inst, const char *key, int *ip_ver);
 uint32_t getIPv4Pref(JNIEnv *env, jobject vpn_inst, const char *key);
 struct in6_addr getIPv6Pref(JNIEnv *env, jobject vpn_inst, const char *key);

app/src/main/jni/pcapd/pcapd.c

@@ -14,7 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with PCAPdroid.  If not, see <http://www.gnu.org/licenses/>.
  *
- * Copyright 2021-23 - Emanuele Faranda
+ * Copyright 2021-24 - Emanuele Faranda
  */
 
 /*

app/src/main/jni/tests/test_utils.c

@@ -89,7 +89,6 @@ pcapdroid_t* pd_init_test(const char *ifname) {
   pd->pcap_file_capture = true;
   pd->pcap.capture_interface = (char*) ifname;
   pd->pcap.as_root = false;   // don't run as root
-  pd->app_filter = -1;        // don't filter
   pd->cb.get_libprog_path = getPcapdPath;
   pd->payload_mode = PAYLOAD_MODE_FULL;
 

app/src/main/res/menu/hint_menu.xml

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="utf-8"?>
+<menu
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
+
+    <item
+        android:id="@+id/show_hint"
+        android:title="@string/hint"
+        android:orderInCategory="5"
+        android:icon="@drawable/ic_info"
+        app:showAsAction="ifRoom" />
+</menu>

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

@@ -501,4 +501,6 @@
     <string name="always">Always</string>
     <string name="for_connections_to_decrypt">Only for connections to decrypt</string>
     <string name="decrypt_quic_notice">Decrypting QUIC is currently not supported. As a workaround, stop the capture and select the option to block QUIC in the PCAPdroid settings</string>
+    <string name="target_apps">Target apps</string>
+    <string name="target_apps_help">Select the applications to capture</string>
 </resources>

docs/app_api.md

@@ -79,7 +79,7 @@ As shown above, the capture settings can be specified by using intent extras. Th
 | Parameter               | Type   | Ver | Mode | Value                                                              |
 |-------------------------|--------|-----|------|--------------------------------------------------------------------|
 | pcap_dump_mode          | string |     |      | none \| http_server \| udp_exporter \| pcap_file                   |
-| app_filter              | string |     |      | the package name of the app to capture                             |
+| app_filter              | string |     |      | package name of the app(s) to capture (73+: comma separated list)  |
 | collector_ip_address    | string |     |      | the IP address of the collector in udp_exporter mode               |
 | collector_port          | int    |     |      | the UDP port of the collector in udp_exporter mode                 |
 | http_server_port        | int    |     |      | the HTTP server port in http_server mode                           |
@@ -101,7 +101,7 @@ As shown above, the capture settings can be specified by using intent extras. Th
 | pcapng_format           | bool   |  62 |      | true to use the PCAPNG dump format (overrides pcapdroid_trailer)*  |
 | socks5_username         | string |  64 | vpn  | username for the optional SOCKS5 proxy authentication              |
 | socks5_password         | string |  64 | vpn  | password for the optional SOCKS5 proxy authentication              |
-| block_quic              | string |  73 | vpn  | never | always | to_decrypt (matching the decryption whitelist)    |
+| block_quic              | string |  73 | vpn  | never \| always \| to_decrypt (matching the decryption whitelist)  |
 
 \*: paid feature