Add socks5 proxy to the remote server check

Also show a message the first time export to a remote server is
tried by the user

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

@@ -22,6 +22,7 @@ package com.emanuelef.remote_capture.activities;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
+import android.content.SharedPreferences;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Handler;
@@ -199,6 +200,27 @@ public class CaptureCtrl extends AppCompatActivity {
         finish();
     }
 
+    // Check if the capture is requesting to send traffic to a remote server.
+    // For security reasons, this is only allowed if such server is already configured by
+    // the user in the app prefs.
+    // see also MainActivity.showRemoteServerAlert
+    private String checkRemoteServerNotAllowed(CaptureSettings settings) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
+
+        if((settings.dump_mode == Prefs.DumpMode.UDP_EXPORTER) &&
+                !Utils.isLocalNetworkAddress(settings.collector_address) &&
+                !Prefs.getCollectorIp(prefs).equals(settings.collector_address))
+            return settings.collector_address;
+
+        if(settings.socks5_enabled &&
+                !Utils.isLocalNetworkAddress(settings.socks5_proxy_address) &&
+                !Prefs.getSocks5ProxyAddress(prefs).equals(settings.socks5_proxy_address))
+            return settings.socks5_proxy_address;
+
+        // ok
+        return null;
+    }
+
     private void processRequest(Intent req_intent, @NonNull String action) {
         Intent res = new Intent();
         Utils.showToast(this, R.string.ctrl_consent_allowed);
@@ -209,13 +231,11 @@ public class CaptureCtrl extends AppCompatActivity {
             Log.d(TAG, "Starting capture, caller=" + mStarterApp);
 
             CaptureSettings settings = new CaptureSettings(req_intent);
-            if((settings.dump_mode == Prefs.DumpMode.UDP_EXPORTER) && (!Utils.isLocalNetworkAddress(settings.collector_address))) {
-                if(!Prefs.getCollectorIp(PreferenceManager.getDefaultSharedPreferences(this)).equals(settings.collector_address)) {
-                    Log.w(TAG, "For security reasons, exporting to the remote UDP collector \"" + settings.collector_address + "\" is disabled");
-                    abort();
-                    return;
-                } else
-                    Log.i(TAG, "Allowing export to remote collector as it matches user pref");
+            String disallowedServer = checkRemoteServerNotAllowed(settings);
+            if(disallowedServer != null) {
+                Utils.showToastLong(this, R.string.remote_server_warning, disallowedServer);
+                abort();
+                return;
             }
 
             // will call the mCapHelper listener

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

@@ -674,6 +674,9 @@ public class MainActivity extends BaseActivity implements NavigationView.OnNavig
     }
 
     public void startCapture() {
+        if(showRemoteServerAlert())
+            return;
+
         if(Prefs.getTlsDecryptionEnabled(mPrefs) && MitmAddon.needsSetup(this)) {
             Intent intent = new Intent(this, MitmSetupWizard.class);
             startActivity(intent);
@@ -700,7 +703,28 @@ public class MainActivity extends BaseActivity implements NavigationView.OnNavig
         CaptureService.stopService();
     }
 
-    public void openFileSelector() {
+    // see also CaptureCtrl.checkRemoteServerNotAllowed
+    private boolean showRemoteServerAlert() {
+        if(mPrefs.getBoolean(Prefs.PREF_REMOTE_COLLECTOR_ACK, false))
+            return false; // already acknowledged
+
+        if(((Prefs.getDumpMode(mPrefs) == Prefs.DumpMode.UDP_EXPORTER) && !Utils.isLocalNetworkAddress(Prefs.getCollectorIp(mPrefs))) ||
+                (Prefs.getSocks5Enabled(mPrefs) && !Utils.isLocalNetworkAddress(Prefs.getSocks5ProxyAddress(mPrefs)))) {
+            Log.i(TAG, "Showing possible scan notice");
+
+            AlertDialog dialog = new AlertDialog.Builder(this)
+                    .setTitle(R.string.scam_alert)
+                    .setMessage(R.string.remote_collector_notice)
+                    .setPositiveButton(R.string.ok, (d, whichButton) -> mPrefs.edit().putBoolean(Prefs.PREF_REMOTE_COLLECTOR_ACK, true).apply())
+                    .show();
+            dialog.setCanceledOnTouchOutside(false);
+            return true;
+        }
+
+        return false;
+    }
+
+    private void openFileSelector() {
         boolean noFileDialog = false;
         String fname = Utils.getUniquePcapFileName(this);
         Intent intent = new Intent(Intent.ACTION_CREATE_DOCUMENT);

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

@@ -77,6 +77,7 @@ public class Prefs {
     public static final String PREF_VPN_EXCEPTIONS = "vpn_exceptions";
     public static final String PREF_BLOCK_NEW_APPS = "block_new_apps";
     public static final String PREF_PAYLOAD_NOTICE_ACK = "payload_notice";
+    public static final String PREF_REMOTE_COLLECTOR_ACK = "remote_collector_notice";
 
     public enum DumpMode {
         NONE,

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

@@ -386,4 +386,6 @@
     <string name="payload_scams_notice">This view may contain sensitive information, like your passwords and access tokens.\n\nNever give out this information to anyone, it may be a scam attempt</string>
     <string name="cancel_action">Cancel</string>
     <string name="show_data_action">Show data</string>
+    <string name="remote_collector_notice">You have configured PCAPdroid to send traffic to a remote server. The server will be able to access your sensitive information.\n\nIf someone asked you to do this, it is probably a scam attempt</string>
+    <string name="remote_server_warning">For security reasons, sending traffic to the remote server \"%1$s\" is not allowed"</string>
 </resources>