2 files changed, 40 insertions, 8 deletions
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 095a7ae7a8..3eff101a3b 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
@@ -139,13 +139,19 @@ class CustomDnsAdapter(val customDns: CustomDns) : Adapter<CustomDnsItemHolder>(
         }
     }
 
-    fun saveDnsServer(address: String) {
+    fun saveDnsServer(address: String, errorCallback: () -> Unit) {
         jobTracker.newUiJob("saveDnsServer $address") {
             editingPosition?.let { position ->
+                var validAddress: Boolean
+                
                 if (position >= cachedCustomDnsServers.size) {
-                    addDnsServer(address)
+                    validAddress = addDnsServer(address)
                 } else {
-                    replaceDnsServer(address, position)
+                    validAddress = replaceDnsServer(address, position)
+                }
+
+                if (!validAddress) {
+                    errorCallback()
                 }
             }
         }
@@ -190,12 +196,12 @@ class CustomDnsAdapter(val customDns: CustomDns) : Adapter<CustomDnsItemHolder>(
         }
     }
 
-    private suspend fun addDnsServer(address: String) {
+    private suspend fun addDnsServer(addressText: String): Boolean {
         var added = false
 
         jobTracker.runOnBackground {
-            if (inetAddressValidator.isValid(address)) {
-                val address = InetAddress.getByName(address)
+            if (inetAddressValidator.isValid(addressText)) {
+                val address = InetAddress.getByName(addressText)
 
                 if (customDns.addDnsServer(address)) {
                     cachedCustomDnsServers.add(address)
@@ -212,9 +218,11 @@ class CustomDnsAdapter(val customDns: CustomDns) : Adapter<CustomDnsItemHolder>(
             notifyItemChanged(count - 3)
             notifyItemInserted(count - 2)
         }
+
+        return added
     }
 
-    private suspend fun replaceDnsServer(address: String, position: Int) {
+    private suspend fun replaceDnsServer(address: String, position: Int): Boolean {
         var replaced = false
 
         jobTracker.runOnBackground {
@@ -233,6 +241,8 @@ class CustomDnsAdapter(val customDns: CustomDns) : Adapter<CustomDnsItemHolder>(
             editingPosition = null
             notifyItemChanged(position)
         }
+
+        return replaced
     }
 
     private fun editDnsServerAt(position: Int?) {
diff --git a/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/EditCustomDnsServerHolder.kt b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/EditCustomDnsServerHolder.kt
index edebc30266..560bfb22d8 100644
--- a/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/EditCustomDnsServerHolder.kt
+++ b/android/src/main/kotlin/net/mullvad/mullvadvpn/ui/customdns/EditCustomDnsServerHolder.kt
@@ -1,5 +1,7 @@
 package net.mullvad.mullvadvpn.ui.customdns
 
+import android.text.Editable
+import android.text.TextWatcher
 import android.view.View
 import android.view.View.OnFocusChangeListener
 import android.widget.EditText
@@ -9,6 +11,10 @@ import net.mullvad.mullvadvpn.R
 import net.mullvad.talpid.util.addressString
 
 class EditCustomDnsServerHolder(view: View, adapter: CustomDnsAdapter) : CustomDnsItemHolder(view) {
+    private val context = view.context
+    private val errorColor = context.getColor(R.color.red)
+    private val normalColor = context.getColor(R.color.blue)
+
     private val input: EditText = view.findViewById<EditText>(R.id.input).apply {
         onFocusChangeListener = OnFocusChangeListener { _, hasFocus ->
             if (!hasFocus) {
@@ -19,6 +25,17 @@ class EditCustomDnsServerHolder(view: View, adapter: CustomDnsAdapter) : CustomD
         }
     }
 
+    private val watcher = object : TextWatcher {
+        override fun beforeTextChanged(text: CharSequence, start: Int, count: Int, after: Int) {}
+
+        override fun afterTextChanged(text: Editable) {
+            input.setTextColor(normalColor)
+            input.removeTextChangedListener(this)
+        }
+
+        override fun onTextChanged(text: CharSequence, start: Int, before: Int, count: Int) {}
+    }
+
     var serverAddress by observable<InetAddress?>(null) { _, _, address ->
         if (address != null) {
             val addressString = address.addressString()
@@ -34,7 +51,12 @@ class EditCustomDnsServerHolder(view: View, adapter: CustomDnsAdapter) : CustomD
 
     init {
         view.findViewById<View>(R.id.save).setOnClickListener {
-            adapter.saveDnsServer(input.text.toString())
+            adapter.saveDnsServer(input.text.toString()) {
+                input.apply {
+                    setTextColor(errorColor)
+                    addTextChangedListener(watcher)
+                }
+            }
         }
     }
 }