Added validation

lib/l10n/app_en.arb

@@ -468,5 +468,6 @@
     "blockingIpv4": "Blocking IPv4",
     "blockingIpv4Description": "IP address to be returned for a blocked A request",
     "blockingIpv6": "Blocking IPv6",
-    "blockingIpv6Description": "IP address to be returned for a blocked AAAA request"
+    "blockingIpv6Description": "IP address to be returned for a blocked AAAA request",
+    "invalidIp": "Invalid IP address"
 }

lib/l10n/app_es.arb

@@ -468,5 +468,6 @@
     "blockingIpv4": "Bloqueo de IPv4",
     "blockingIpv4Description": "Dirección IP devolverá una petición A bloqueada",
     "blockingIpv6": "Bloqueo de IPv6",
-    "blockingIpv6Description": "Dirección IP devolverá una petición AAAA bloqueada"
+    "blockingIpv6Description": "Dirección IP devolverá una petición AAAA bloqueada",
+    "invalidIp": "Dirección IP no válida"
 }

lib/screens/settings/dns/bootstrap_dns.dart

@@ -16,15 +16,45 @@ class BootstrapDnsScreen extends StatefulWidget {
 }
 
 class _BootstrapDnsScreenState extends State<BootstrapDnsScreen> {
-  List<TextEditingController> bootstrapControllers = [];
+  List<Map<String, dynamic>> bootstrapControllers = [];
+
+  bool validValues = false;
+
+  void validateIp(Map<String, dynamic> field, String value) {
+    RegExp ipAddress = RegExp(r'(?:^(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}$)|(?:^(?:(?:[a-fA-F\d]{1,4}:){7}(?:[a-fA-F\d]{1,4}|:)|(?:[a-fA-F\d]{1,4}:){6}(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|:[a-fA-F\d]{1,4}|:)|(?:[a-fA-F\d]{1,4}:){5}(?::(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,2}|:)|(?:[a-fA-F\d]{1,4}:){4}(?:(?::[a-fA-F\d]{1,4}){0,1}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,3}|:)|(?:[a-fA-F\d]{1,4}:){3}(?:(?::[a-fA-F\d]{1,4}){0,2}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,4}|:)|(?:[a-fA-F\d]{1,4}:){2}(?:(?::[a-fA-F\d]{1,4}){0,3}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,5}|:)|(?:[a-fA-F\d]{1,4}:){1}(?:(?::[a-fA-F\d]{1,4}){0,4}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,6}|:)|(?::(?:(?::[a-fA-F\d]{1,4}){0,5}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,7}|:)))(?:%[0-9a-zA-Z]{1,})?$)');
+    if (ipAddress.hasMatch(value) == true) {
+      setState(() => field['error'] = null);
+    }
+    else {
+      setState(() => field['error'] = AppLocalizations.of(context)!.invalidIp);
+    }
+    checkValidValues();
+  }
+
+  void checkValidValues() {
+    if (
+      bootstrapControllers.isNotEmpty &&
+      bootstrapControllers.every((element) => element['controller'].text != '') &&
+      bootstrapControllers.every((element) => element['error'] == null)
+    ) {
+      setState(() => validValues = true);
+    }
+    else {
+      setState(() => validValues = false);
+    }
+  }
 
   @override
   void initState() {
     for (var item in widget.serversProvider.dnsInfo.data!.bootstrapDns) {
       final controller = TextEditingController();
       controller.text = item;
-      bootstrapControllers.add(controller);
+      bootstrapControllers.add({
+        'controller': controller,
+        'error': null
+      });
     }
+    validValues = true;
     super.initState();
   }
 
@@ -33,6 +63,16 @@ class _BootstrapDnsScreenState extends State<BootstrapDnsScreen> {
     return Scaffold(
       appBar: AppBar(
         title: Text(AppLocalizations.of(context)!.bootstrapDns),
+        actions: [
+          IconButton(
+            onPressed: validValues == true
+              ? () => {}
+              : null, 
+            icon: const Icon(Icons.save_rounded),
+            tooltip: AppLocalizations.of(context)!.save,
+          ),
+          const SizedBox(width: 10)
+        ],
       ),
       body: ListView(
         padding: const EdgeInsets.only(top: 10),
@@ -83,8 +123,8 @@ class _BootstrapDnsScreenState extends State<BootstrapDnsScreen> {
                 SizedBox(
                   width: MediaQuery.of(context).size.width-90,
                   child: TextFormField(
-                    controller: c,
-                    // onChanged: (_) => checkValidValues(),
+                    controller: c['controller'],
+                    onChanged: (value) => validateIp(c, value),
                     decoration: InputDecoration(
                       prefixIcon: const Icon(Icons.dns_rounded),
                       border: const OutlineInputBorder(
@@ -92,12 +132,16 @@ class _BootstrapDnsScreenState extends State<BootstrapDnsScreen> {
                           Radius.circular(10)
                         )
                       ),
+                      errorText: c['error'],
                       labelText: AppLocalizations.of(context)!.dnsServer,
                     )
                   ),
                 ),
                 IconButton(
-                  onPressed: () => setState(() => bootstrapControllers = bootstrapControllers.where((con) => con != c).toList()), 
+                  onPressed: () {
+                    setState(() => bootstrapControllers = bootstrapControllers.where((con) => con != c).toList());
+                    checkValidValues();
+                  }, 
                   icon: const Icon(Icons.remove_circle_outline)
                 )
               ],
@@ -108,7 +152,13 @@ class _BootstrapDnsScreenState extends State<BootstrapDnsScreen> {
             mainAxisSize: MainAxisSize.min,
             children: [
               ElevatedButton.icon(
-                onPressed: () => setState(() => bootstrapControllers.add(TextEditingController())), 
+                onPressed: () {
+                  setState(() => bootstrapControllers.add({
+                    'controller': TextEditingController(),
+                    'error': null
+                  }));
+                  checkValidValues();
+                }, 
                 icon: const Icon(Icons.add), 
                 label: Text(AppLocalizations.of(context)!.addItem)
               ),

lib/screens/settings/dns/cache_config.dart

@@ -29,12 +29,31 @@ class _CacheConfigDnsScreenState extends State<CacheConfigDnsScreen> {
 
   bool optimisticCache = false;
 
+  bool validData = false;
+
+  void checkValidData() {
+    if (
+      cacheSizeController.text != '' &&
+      cacheSizeError == null &&
+      overrideMinTtlController.text != '' && 
+      overrideMinTtlError == null && 
+      overrideMaxTtlController.text != '' && 
+      overrideMaxTtlError == null
+    ) {
+      setState(() => validData = true);
+    }
+    else {
+      setState(() => validData = false);
+    }
+  }
+
   @override
   void initState() {
     cacheSizeController.text = widget.serversProvider.dnsInfo.data!.cacheSize.toString();
     overrideMinTtlController.text = widget.serversProvider.dnsInfo.data!.cacheTtlMin.toString();
     overrideMaxTtlController.text = widget.serversProvider.dnsInfo.data!.cacheTtlMax.toString();
     optimisticCache = widget.serversProvider.dnsInfo.data!.cacheOptimistic;
+    validData = true;
     super.initState();
   }
 
@@ -73,6 +92,16 @@ class _CacheConfigDnsScreenState extends State<CacheConfigDnsScreen> {
     return Scaffold(
       appBar: AppBar(
         title: Text(AppLocalizations.of(context)!.dnsCacheConfig),
+        actions: [
+          IconButton(
+            onPressed: validData == true
+              ? () => {}
+              : null, 
+            icon: const Icon(Icons.save_rounded),
+            tooltip: AppLocalizations.of(context)!.save,
+          ),
+          const SizedBox(width: 10)
+        ],
       ),
       body: ListView(
         padding: const EdgeInsets.only(top: 10),
@@ -89,6 +118,7 @@ class _CacheConfigDnsScreenState extends State<CacheConfigDnsScreen> {
               else {
                 setState(() => cacheSizeError = AppLocalizations.of(context)!.valueNotNumber);
               }
+              checkValidData();
             }
           ),
           const SizedBox(height: 30),
@@ -104,6 +134,7 @@ class _CacheConfigDnsScreenState extends State<CacheConfigDnsScreen> {
               else {
                 setState(() => overrideMinTtlError = AppLocalizations.of(context)!.valueNotNumber);
               }
+              checkValidData();
             }
           ),
           const SizedBox(height: 30),
@@ -119,6 +150,7 @@ class _CacheConfigDnsScreenState extends State<CacheConfigDnsScreen> {
               else {
                 setState(() => overrideMaxTtlError = AppLocalizations.of(context)!.valueNotNumber);
               }
+              checkValidData();
             }
           ),
           const SizedBox(height: 10),

lib/screens/settings/dns/dns_server_settings.dart

@@ -33,6 +33,52 @@ class _DnsServerSettingsScreenState extends State<DnsServerSettingsScreen> {
   final TextEditingController ipv6controller = TextEditingController();
   String? ipv6error;
 
+  bool isDataValid = false;
+
+  void validateIpv4(String value) {
+    RegExp ipAddress = RegExp(r'^((25[0-5]|(2[0-4]|1\d|[1-9]|)\d)\.?\b){4}$');
+    if (ipAddress.hasMatch(value) == true) {
+      setState(() => ipv4error = null);
+    }
+    else {
+      setState(() => ipv4error = AppLocalizations.of(context)!.invalidIp);
+    }
+    validateData();
+  }
+
+  void validateIpv6(String value) {
+    RegExp ipAddress = RegExp(r'(?:^(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}$)|(?:^(?:(?:[a-fA-F\d]{1,4}:){7}(?:[a-fA-F\d]{1,4}|:)|(?:[a-fA-F\d]{1,4}:){6}(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|:[a-fA-F\d]{1,4}|:)|(?:[a-fA-F\d]{1,4}:){5}(?::(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,2}|:)|(?:[a-fA-F\d]{1,4}:){4}(?:(?::[a-fA-F\d]{1,4}){0,1}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,3}|:)|(?:[a-fA-F\d]{1,4}:){3}(?:(?::[a-fA-F\d]{1,4}){0,2}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,4}|:)|(?:[a-fA-F\d]{1,4}:){2}(?:(?::[a-fA-F\d]{1,4}){0,3}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,5}|:)|(?:[a-fA-F\d]{1,4}:){1}(?:(?::[a-fA-F\d]{1,4}){0,4}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,6}|:)|(?::(?:(?::[a-fA-F\d]{1,4}){0,5}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,7}|:)))(?:%[0-9a-zA-Z]{1,})?$)');
+    if (ipAddress.hasMatch(value) == true) {
+      setState(() => ipv6error = null);
+    }
+    else {
+      setState(() => ipv6error = AppLocalizations.of(context)!.invalidIp);
+    }
+    validateData();
+  }
+
+  void validateData() {
+    if (
+      limitRequestsController.text != '' &&
+      limitRequestsError == null &&
+      (
+        blockingMode != 'custom_ip' ||
+        (
+          blockingMode == 'custom_ip' && 
+          ipv4controller.text != '' &&
+          ipv4error == null &&
+          ipv6controller.text != '' &&
+          ipv6error == null
+        )
+      ) == true
+    ) {
+      setState(() => isDataValid = true);
+    }
+    else {
+      setState(() => isDataValid = false);
+    }
+  }
+
   @override
   void initState() {
     limitRequestsController.text = widget.serversProvider.dnsInfo.data!.ratelimit.toString();
@@ -42,6 +88,7 @@ class _DnsServerSettingsScreenState extends State<DnsServerSettingsScreen> {
     blockingMode = widget.serversProvider.dnsInfo.data!.blockingMode;
     ipv4controller.text = widget.serversProvider.dnsInfo.data!.blockingIpv4;
     ipv6controller.text = widget.serversProvider.dnsInfo.data!.blockingIpv6;
+    isDataValid = true;
     super.initState();
   }
 
@@ -56,11 +103,22 @@ class _DnsServerSettingsScreenState extends State<DnsServerSettingsScreen> {
         ipv6error = null;
       }
       setState(() => blockingMode = mode);
+      validateData();
     }
 
     return Scaffold(
       appBar: AppBar(
         title: Text(AppLocalizations.of(context)!.dnsServerSettings),
+        actions: [
+          IconButton(
+            onPressed: isDataValid == true
+              ? () => {}
+              : null, 
+            icon: const Icon(Icons.save_rounded),
+            tooltip: AppLocalizations.of(context)!.save,
+          ),
+          const SizedBox(width: 10)
+        ],
       ),
       body: ListView(
         padding: const EdgeInsets.only(top: 10),
@@ -76,6 +134,7 @@ class _DnsServerSettingsScreenState extends State<DnsServerSettingsScreen> {
                 else {
                   setState(() => limitRequestsError = AppLocalizations.of(context)!.valueNotNumber);
                 }
+                validateData();
               },
               decoration: InputDecoration(
                 prefixIcon: const Icon(Icons.looks_one_rounded),
@@ -156,7 +215,7 @@ class _DnsServerSettingsScreenState extends State<DnsServerSettingsScreen> {
               padding: const EdgeInsets.symmetric(horizontal: 24),
               child: TextFormField(
                 controller: ipv4controller,
-                // onChanged: onChanged,
+                onChanged: validateIpv4,
                 decoration: InputDecoration(
                   prefixIcon: const Icon(Icons.link_rounded),
                   border: const OutlineInputBorder(
@@ -177,7 +236,7 @@ class _DnsServerSettingsScreenState extends State<DnsServerSettingsScreen> {
               padding: const EdgeInsets.symmetric(horizontal: 24),
               child: TextFormField(
                 controller: ipv6controller,
-                // onChanged: onChanged,
+                onChanged: validateIpv6,
                 decoration: InputDecoration(
                   prefixIcon: const Icon(Icons.link_rounded),
                   border: const OutlineInputBorder(

lib/screens/settings/dns/private_reverse_servers.dart

@@ -20,12 +20,46 @@ class PrivateReverseDnsServersScreen extends StatefulWidget {
 class _PrivateReverseDnsServersScreenState extends State<PrivateReverseDnsServersScreen> {
   List<String> defaultReverseResolvers = [];
   bool editReverseResolvers = false;
-  List<TextEditingController> reverseResolversControllers = [
-    TextEditingController()
+  List<Map<String, dynamic>> reverseResolversControllers = [
+    {
+      'controller': TextEditingController(),
+      'error': null
+    }
   ];
   bool usePrivateReverseDnsResolvers = false;
   bool enableReverseResolve = false;
 
+  bool validValues = false;
+
+  void validateAddress(Map<String, dynamic> item ,String value) {
+    RegExp ipAddress = RegExp(r'(?:^(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}$)|(?:^(?:(?:[a-fA-F\d]{1,4}:){7}(?:[a-fA-F\d]{1,4}|:)|(?:[a-fA-F\d]{1,4}:){6}(?:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|:[a-fA-F\d]{1,4}|:)|(?:[a-fA-F\d]{1,4}:){5}(?::(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,2}|:)|(?:[a-fA-F\d]{1,4}:){4}(?:(?::[a-fA-F\d]{1,4}){0,1}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,3}|:)|(?:[a-fA-F\d]{1,4}:){3}(?:(?::[a-fA-F\d]{1,4}){0,2}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,4}|:)|(?:[a-fA-F\d]{1,4}:){2}(?:(?::[a-fA-F\d]{1,4}){0,3}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,5}|:)|(?:[a-fA-F\d]{1,4}:){1}(?:(?::[a-fA-F\d]{1,4}){0,4}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,6}|:)|(?::(?:(?::[a-fA-F\d]{1,4}){0,5}:(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)(?:\\.(?:25[0-5]|2[0-4]\d|1\d\d|[1-9]\d|\d)){3}|(?::[a-fA-F\d]{1,4}){1,7}|:)))(?:%[0-9a-zA-Z]{1,})?$)');
+    RegExp domain = RegExp(r'^((http|https|tls|udp|tcp|quic|sdns):\/\/)?([a-z0-9|-]+\.)*[a-z0-9|-]+\.[a-z]+$');
+    if (ipAddress.hasMatch(value) == true || domain.hasMatch(value) == true) {
+      setState(() => item['error'] = null);
+    }
+    else {
+      setState(() => item['error'] = AppLocalizations.of(context)!.invalidIpDomain);
+    }
+
+    checkDataValid();
+  }
+
+  void checkDataValid() {
+    if (
+      (
+        editReverseResolvers == true &&
+        reverseResolversControllers.isNotEmpty &&
+        reverseResolversControllers.every((element) => element['controller'].text != '') &&
+        reverseResolversControllers.every((element) => element['error'] == null)
+      ) == true
+    ) {
+      setState(() => validValues = true);
+    }
+    else {
+      setState(() => validValues = false);
+    }
+  }
+
   @override
   void initState() {
     for (var item in widget.serversProvider.dnsInfo.data!.defaultLocalPtrUpstreams) {
@@ -34,13 +68,17 @@ class _PrivateReverseDnsServersScreenState extends State<PrivateReverseDnsServer
     for (var item in widget.serversProvider.dnsInfo.data!.localPtrUpstreams) {
       final controller = TextEditingController();
       controller.text = item;
-      reverseResolversControllers.add(controller);
+      reverseResolversControllers.add({
+        'controller': controller,
+        'error': null
+      });
     }
     if (widget.serversProvider.dnsInfo.data!.localPtrUpstreams.isNotEmpty) {
       editReverseResolvers = true;
     }
     usePrivateReverseDnsResolvers = widget.serversProvider.dnsInfo.data!.usePrivatePtrResolvers;
     enableReverseResolve = widget.serversProvider.dnsInfo.data!.resolveClients;
+    validValues = true;
     super.initState();
   }
 
@@ -49,6 +87,16 @@ class _PrivateReverseDnsServersScreenState extends State<PrivateReverseDnsServer
     return Scaffold(
       appBar: AppBar(
         title: Text(AppLocalizations.of(context)!.privateReverseDnsServers),
+        actions: [
+          IconButton(
+            onPressed: validValues == true
+              ? () => {}
+              : null, 
+            icon: const Icon(Icons.save_rounded),
+            tooltip: AppLocalizations.of(context)!.save,
+          ),
+          const SizedBox(width: 10)
+        ],
       ),
       body: ListView(
         padding: const EdgeInsets.only(top: 10),
@@ -90,7 +138,10 @@ class _PrivateReverseDnsServersScreenState extends State<PrivateReverseDnsServer
                 mainAxisAlignment: MainAxisAlignment.center,
                 children: [
                   ElevatedButton.icon(
-                    onPressed: () => setState(() => editReverseResolvers = true), 
+                    onPressed: () {
+                      setState(() => editReverseResolvers = true);
+                      checkDataValid();
+                    }, 
                     icon: const Icon(Icons.edit), 
                     label: Text(AppLocalizations.of(context)!.edit)
                   ),
@@ -110,8 +161,8 @@ class _PrivateReverseDnsServersScreenState extends State<PrivateReverseDnsServer
                   SizedBox(
                     width: MediaQuery.of(context).size.width-90,
                     child: TextFormField(
-                      controller: c,
-                      // onChanged: (_) => checkValidValues(),
+                      controller: c['controller'],
+                      onChanged: (value) => validateAddress(c, value),
                       decoration: InputDecoration(
                         prefixIcon: const Icon(Icons.dns_rounded),
                         border: const OutlineInputBorder(
@@ -119,12 +170,16 @@ class _PrivateReverseDnsServersScreenState extends State<PrivateReverseDnsServer
                             Radius.circular(10)
                           )
                         ),
+                        errorText: c['error'],
                         labelText: AppLocalizations.of(context)!.serverAddress,
                       )
                     ),
                   ),
                   IconButton(
-                    onPressed: () => setState(() => reverseResolversControllers = reverseResolversControllers.where((con) => con != c).toList()), 
+                    onPressed: () {
+                      setState(() => reverseResolversControllers = reverseResolversControllers.where((con) => con != c).toList());
+                      checkDataValid();
+                    }, 
                     icon: const Icon(Icons.remove_circle_outline)
                   )
                 ],
@@ -152,7 +207,13 @@ class _PrivateReverseDnsServersScreenState extends State<PrivateReverseDnsServer
                 mainAxisSize: MainAxisSize.min,
                 children: [
                   ElevatedButton.icon(
-                    onPressed: () => setState(() => reverseResolversControllers.add(TextEditingController())), 
+                    onPressed: () {
+                      setState(() => reverseResolversControllers.add({
+                        'controller': TextEditingController(),
+                        'error': null
+                      }));
+                      checkDataValid();
+                    }, 
                     icon: const Icon(Icons.add), 
                     label: Text(AppLocalizations.of(context)!.addItem)
                   ),

lib/screens/settings/dns/upstream_dns.dart

@@ -21,7 +21,21 @@ class UpstreamDnsScreen extends StatefulWidget {
 class _UpstreamDnsScreenState extends State<UpstreamDnsScreen> {
   List<TextEditingController> upstreamControllers = [];
 
-  String upstreamMode = "load_balancing";
+  String upstreamMode = "";
+
+  bool validValues = false;
+
+  checkValidValues() {
+    if (
+      upstreamControllers.isNotEmpty &&
+      upstreamControllers.every((element) => element.text != '')
+    ) {
+      setState(() => validValues = true);
+    }
+    else {
+      setState(() => validValues = false);
+    }
+  }
 
   @override
   void initState() {
@@ -31,6 +45,7 @@ class _UpstreamDnsScreenState extends State<UpstreamDnsScreen> {
       upstreamControllers.add(controller);
     }
     upstreamMode = widget.serversProvider.dnsInfo.data!.upstreamMode;
+    validValues = true;
     super.initState();
   }
 
@@ -39,6 +54,16 @@ class _UpstreamDnsScreenState extends State<UpstreamDnsScreen> {
     return Scaffold(
       appBar: AppBar(
         title: Text(AppLocalizations.of(context)!.upstreamDns),
+        actions: [
+          IconButton(
+            onPressed: validValues == true
+              ? () => {}
+              : null, 
+            icon: const Icon(Icons.save_rounded),
+            tooltip: AppLocalizations.of(context)!.save,
+          ),
+          const SizedBox(width: 10)
+        ],
       ),
       body: ListView(
         padding: const EdgeInsets.only(top: 10),
@@ -71,7 +96,7 @@ class _UpstreamDnsScreenState extends State<UpstreamDnsScreen> {
                   width: MediaQuery.of(context).size.width-90,
                   child: TextFormField(
                     controller: c,
-                    // onChanged: (_) => checkValidValues(),
+                    onChanged: (_) => checkValidValues(),
                     decoration: InputDecoration(
                       prefixIcon: const Icon(Icons.dns_rounded),
                       border: const OutlineInputBorder(
@@ -84,7 +109,10 @@ class _UpstreamDnsScreenState extends State<UpstreamDnsScreen> {
                   ),
                 ),
                 IconButton(
-                  onPressed: () => setState(() => upstreamControllers = upstreamControllers.where((con) => con != c).toList()), 
+                  onPressed: () {
+                    setState(() => upstreamControllers = upstreamControllers.where((con) => con != c).toList());
+                    checkValidValues();
+                  }, 
                   icon: const Icon(Icons.remove_circle_outline)
                 )
               ],
@@ -95,7 +123,10 @@ class _UpstreamDnsScreenState extends State<UpstreamDnsScreen> {
             mainAxisSize: MainAxisSize.min,
             children: [
               ElevatedButton.icon(
-                onPressed: () => setState(() => upstreamControllers.add(TextEditingController())), 
+                onPressed: () {
+                  setState(() => upstreamControllers.add(TextEditingController()));
+                  checkValidValues();
+                }, 
                 icon: const Icon(Icons.add), 
                 label: Text(AppLocalizations.of(context)!.addItem)
               ),