Warn when trying to add public DNS address

2 files changed, 21 insertions, 2 deletions

diff --git a/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/AdvancedFragment.kt b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/AdvancedFragment.kt
index bdeb4a879c..f02f5cca91 100644
--- a/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/AdvancedFragment.kt
+++ b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/AdvancedFragment.kt
@@ -36,7 +36,11 @@ class AdvancedFragment : ServiceDependentFragment(OnNoService.GoBack) {
 
         titleController = CollapsibleTitleController(view, R.id.contents)
 
-        customDnsAdapter = CustomDnsAdapter(customDns)
+        customDnsAdapter = CustomDnsAdapter(customDns).apply {
+            showPublicDnsAddressWarning = { confirmation ->
+                showConfirmPublicDnsServerDialog(confirmation)
+            }
+        }
 
         view.findViewById<CustomRecyclerView>(R.id.contents).apply {
             layoutManager = LinearLayoutManager(parentActivity)
diff --git a/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/CustomDnsAdapter.kt b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/CustomDnsAdapter.kt
index 5c3eeee3a5..44af15c1f7 100644
--- a/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/CustomDnsAdapter.kt
+++ b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/CustomDnsAdapter.kt
@@ -5,6 +5,7 @@ import android.view.LayoutInflater
 import android.view.ViewGroup
 import java.net.InetAddress
 import kotlin.properties.Delegates.observable
+import kotlinx.coroutines.CompletableDeferred
 import kotlinx.coroutines.sync.Mutex
 import kotlinx.coroutines.sync.withLock
 import net.mullvad.mullvadvpn.R
@@ -53,6 +54,8 @@ class CustomDnsAdapter(val customDns: CustomDns) : Adapter<CustomDnsItemHolder>(
     val isEditing
         get() = editingPosition != null
 
+    var showPublicDnsAddressWarning: ((CompletableDeferred<Boolean>) -> Unit)? = null
+
     init {
         customDns.apply {
             onDnsServersChanged.subscribe(this) { dnsServers ->
@@ -282,10 +285,22 @@ class CustomDnsAdapter(val customDns: CustomDns) : Adapter<CustomDnsItemHolder>(
             if (inetAddressValidator.isValid(addressText)) {
                 val address = InetAddress.getByName(addressText)
 
-                if (!address.isLoopbackAddress()) {
+                if (!address.isLoopbackAddress() && confirmAddIfPublicAddress(address)) {
                     handler(address)
                 }
             }
         }
     }
+
+    private suspend fun confirmAddIfPublicAddress(address: InetAddress): Boolean {
+        if (address.isLinkLocalAddress() || address.isSiteLocalAddress()) {
+            return true
+        }
+
+        val confirmation = CompletableDeferred<Boolean>()
+
+        showPublicDnsAddressWarning?.invoke(confirmation)
+
+        return confirmation.await()
+    }
 }