Refactor getNetworkForIp for Android<=10, use RouteInfo instead of LinkAddress

* In Android 10, with previous versions of Android SDK this fallback was working but something changed. The previous logic was incorrect and was matching the host ip (current device) with the targetHostIp (the device we want to connect to).
* Code is now more robust and uses DHCP (A11+) or Route info (A10 or older, and A11+ if DHCP fails)

Author: davidalo

android/src/main/java/com/ReactNativeBlobUtil/ReactNativeBlobUtilReq.java

@@ -12,8 +12,9 @@
 import android.net.NetworkInfo;
 import android.net.Uri;
 import android.net.LinkProperties;
-import android.net.LinkAddress;
-import java.net.Inet4Address;  
+import android.net.RouteInfo;
+import java.net.Inet4Address;
+import java.net.InetAddress;
 import android.os.Build;
 import android.os.Bundle;
 import android.os.Environment;
@@ -44,6 +45,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.net.MalformedURLException;
+import java.net.UnknownHostException;
 import java.net.Proxy;
 import java.net.SocketException;
 import java.net.SocketTimeoutException;
@@ -391,10 +393,22 @@ else if (this.options.fileCache)
 
             // wifi only, need ACCESS_NETWORK_STATE permission
             // and API level >= 21
-            boolean targetHostIpAvailable = (this.options.targetHostIp != null && !this.options.targetHostIp.isEmpty());
+            final String targetHostIp = this.options.targetHostIp;
+            boolean targetHostIpAvailable = (targetHostIp != null && !targetHostIp.isEmpty());
+            
             if (this.options.wifiOnly) {
                 boolean found = false;
 
+                // convert targetHostIp from String into InetAddress
+                InetAddress targetHostAddr = null;
+                if (targetHostIpAvailable) {
+                    try {
+                        targetHostAddr = InetAddress.getByName(targetHostIp);
+                    } catch (UnknownHostException e) {
+                        targetHostAddr = null; // skip
+                    }
+                }
+
                 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                     ConnectivityManager connectivityManager = (ConnectivityManager) ReactNativeBlobUtilImpl.RCTContext.getSystemService(ReactNativeBlobUtilImpl.RCTContext.CONNECTIVITY_SERVICE);
                     Network[] networks = connectivityManager.getAllNetworks();
@@ -408,9 +422,7 @@ else if (this.options.fileCache)
 
                         // if targetHostIpAvailable does not match, fallback to any wifi
                         if (targetHostIpAvailable) {
-                            String targetHostIp = this.options.targetHostIp;
-
-                            if (networkMatchesTargetIp(connectivityManager, network, targetHostIp)) {
+                            if (networkMatchesTargetIp(connectivityManager, network, targetHostIp, targetHostAddr)) {
                                 clientBuilder.proxy(Proxy.NO_PROXY);
                                 clientBuilder.socketFactory(network.getSocketFactory());
                                 found = true;
@@ -1048,28 +1060,33 @@ private boolean isValidWifiNetwork(ConnectivityManager cm, Network network) {
     /**
      * Check if a network matches the target host IP address
      */
-    private boolean networkMatchesTargetIp(ConnectivityManager cm, Network network, String targetHostIp) {
+    private boolean networkMatchesTargetIp(ConnectivityManager cm, Network network, String targetHostIp, InetAddress targetHostAddr) {
         LinkProperties lp = cm.getLinkProperties(network);
         if (lp == null) return false;
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
-            // For Android R and above, use DHCP server address
+            // For Android 11 and above, use DHCP server address
             Inet4Address dhcpServer = lp.getDhcpServerAddress();
             if (dhcpServer != null && dhcpServer.getHostAddress().equals(targetHostIp)) {
                 return true;
             }
         }
-        
-        // Always fall back to linkAddresses check
-        List<LinkAddress> linkAddresses = lp.getLinkAddresses();
-        if (linkAddresses != null && !linkAddresses.isEmpty()) {
-            for (LinkAddress la : linkAddresses) {
-                if (la.getAddress().getHostAddress().equals(targetHostIp)) {
-                    return true;
+
+        // For older versions or Android 11+ if DHCP does not match, check routing table
+        if (targetHostAddr != null) {
+            List<RouteInfo> routes = lp.getRoutes();
+            if (routes != null) {
+                for (RouteInfo route : routes) {
+                    if (route.isDefaultRoute()) {
+                        continue;
+                    }
+                    if (route.matches(targetHostAddr)) {
+                        return true;
+                    }
                 }
             }
         }
-        
+
         return false;
     }
 }