From 4e74f519e1ec2a5fb7bbb383db6378d6d9e21dc7 Mon Sep 17 00:00:00 2001
From: Zoltan Papp <zoltan.pmail@gmail.com>
Date: Sun, 26 May 2024 14:31:26 +0200
Subject: [PATCH] fix unmodifiable List type (#20)

The Android SDK returns with an unmodifiable Link type. The code tries to touch this list and it causes an exception.
---
 .../java/io/netbird/client/tool/DNSWatch.java | 28 +++++++++++--------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/android/tool/src/main/java/io/netbird/client/tool/DNSWatch.java b/android/tool/src/main/java/io/netbird/client/tool/DNSWatch.java
index 960aacf..d976769 100644
--- a/android/tool/src/main/java/io/netbird/client/tool/DNSWatch.java
+++ b/android/tool/src/main/java/io/netbird/client/tool/DNSWatch.java
@@ -13,6 +13,7 @@
 
 import java.net.InetAddress;
 import java.net.UnknownHostException;
+import java.util.ArrayList;
 import java.util.List;
 
 import io.netbird.gomobile.android.DNSList;
@@ -67,8 +68,7 @@ private DNSList readActiveDns() {
             isPrivateDnsActive = props.isPrivateDnsActive();
         }
 
-        List<InetAddress> list = props.getDnsServers();
-        extendWithFallbackDNS(list);
+        List<InetAddress>  list = extendWithFallbackDNS(props.getDnsServers());
         return toDnsList(list);
     }
 
@@ -84,8 +84,8 @@ private void registerNetworkCallback() {
     }
 
     private synchronized void onNewDNSList(LinkProperties linkProperties) {
-        List<InetAddress> newDNSList = linkProperties.getDnsServers();
-        extendWithFallbackDNS(newDNSList);
+        List<InetAddress>  newDNSList = extendWithFallbackDNS(linkProperties.getDnsServers());
+
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
             isPrivateDnsActive = linkProperties.isPrivateDnsActive();
@@ -117,16 +117,22 @@ private synchronized void onNewDNSList(LinkProperties linkProperties) {
         }
     }
 
-    private void extendWithFallbackDNS(List<InetAddress> dnsServers) {
+    private List<InetAddress> extendWithFallbackDNS(List<InetAddress> dnsServers) {
+        List<InetAddress> modifiableDnsServers = new ArrayList<>(dnsServers);
+
         if (dnsServers.isEmpty()) {
-            return;
+            return modifiableDnsServers;
         }
-        if (dnsServers.get(0).isLinkLocalAddress()) {
-            try {
-                InetAddress addr = InetAddress.getByName("1.1.1.1");
-                dnsServers.add(0, addr);
-            } catch (UnknownHostException e) {}
+
+        if (!dnsServers.get(0).isLinkLocalAddress()) {
+            return modifiableDnsServers;
         }
+
+        try {
+            InetAddress addr = InetAddress.getByName("1.1.1.1");
+            modifiableDnsServers.add(0, addr);
+        } catch (UnknownHostException e) {}
+        return modifiableDnsServers;
     }
 
     private void notifyDnsWatcher(DNSList dnsServers) throws Exception {