Fix Android VPN traffic from external apps

clients/android/app/build.gradle

@@ -30,8 +30,8 @@ android {
         applicationId "su.cin.rapvpn"
         minSdk 26
         targetSdk 35
-        versionCode 182
-        versionName "0.2.182"
+        versionCode 183
+        versionName "0.2.183"
         buildConfigField "String", "DEFAULT_BACKEND_URL", "\"${normalizeGradleString(defaultBackendUrl)}\""
         buildConfigField "String", "DEFAULT_CLUSTER_ID", "\"${normalizeGradleString(defaultClusterId)}\""
         buildConfigField "String", "DEFAULT_ORGANIZATION_ID", "\"${normalizeGradleString(defaultOrganizationId)}\""

clients/android/app/src/main/java/su/cin/rapvpn/RapVpnService.java

@@ -1771,12 +1771,16 @@ public class RapVpnService extends VpnService {
         byte[] copy = new byte[length];
         System.arraycopy(packet, 0, copy, 0, length);
         if (!hasIPv4Source(copy, length)) {
+            String natKey = natKeyForOutboundReturn(copy, length);
+            if (natKey.isEmpty() || !rewriteIPv4SourceToVPN(copy, length, natKey)) {
                 long mismatch = uplinkSourceMismatchPackets.incrementAndGet();
                 Log.w(TAG, "vpn uplink source is not vpn address; dropping " + packetSummary(copy, length));
                 writeRuntimeDetail("source_drop", packetSummary(copy, length), "uplink", -1, mismatch, "SOURCE_MISMATCH");
                 recordUplinkDrop(length);
                 return;
             }
+            writeRuntimeDetail("source_nat", packetSummary(copy, length), "uplink", -1, -1, "");
+        }
         if (clampIPv4TCPMSS(copy, length, VPN_TCP_MSS_CLAMP)) {
             writeRuntimeDetail("tcp_mss_clamp", packetSummary(copy, length), "uplink_tcp", -1, -1, "");
         }