New: Newznab providers will be rejected if they are not valid addresses.

Tests added for checking DNS.

NzbDrone.Core.Test/ProviderTests/NewznabProviderTest.cs

@@ -9,6 +9,7 @@ using NzbDrone.Core.Providers;
 using NzbDrone.Core.Repository;
 using NzbDrone.Core.Repository.Quality;
 using NzbDrone.Core.Test.Framework;
+using NzbDrone.Test.Common;
 using NzbDrone.Test.Common.AutoMoq;
 
 namespace NzbDrone.Core.Test.ProviderTests
@@ -295,5 +296,19 @@ namespace NzbDrone.Core.Test.ProviderTests
             var result = db.Fetch<NewznabDefinition>();
             result.Should().HaveCount(2);
         }
+
+        [Test]
+        public void CheckHostname_should_do_nothing_if_hostname_is_valid()
+        {
+            Mocker.Resolve<NewznabProvider>().CheckHostname("http://www.google.com");
+        }
+
+        [Test]
+        [ExpectedException("System.Net.Sockets.SocketException")]  
+        public void CheckHostname_should_log_error_and_throw_exception_if_dnsHostname_is_invalid()
+        {
+            Mocker.Resolve<NewznabProvider>().CheckHostname("http://BadName");
+            ExceptionVerification.ExpectedErrors(1);
+        }
     }
 }

NzbDrone.Core/Providers/NewznabProvider.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Net;
 using Ninject;
 using NLog;
 using NzbDrone.Core.Providers.Indexer;
@@ -56,7 +57,11 @@ namespace NzbDrone.Core.Providers
             var definitionsList = definitions.ToList();
 
             //Cleanup the URL for each definition
-            definitionsList.ForEach(p => p.Url = (new Uri(p.Url).ParentUriString()));
+            foreach(var newznabDefinition in definitionsList)
+            {
+                CheckHostname(newznabDefinition.Url);
+                newznabDefinition.Url = new Uri(newznabDefinition.Url).ParentUriString();
+            }
 
             _database.UpdateMany(definitionsList);
         }
@@ -99,5 +104,22 @@ namespace NzbDrone.Core.Providers
         {
             _database.Delete<NewznabDefinition>(id);
         }
+
+        public virtual void CheckHostname(string url)
+        {
+            try
+            {
+                var uri = new Uri(url);
+                var hostname = uri.DnsSafeHost;
+
+                Dns.GetHostEntry(hostname);
+            }
+            catch (Exception ex)
+            {
+                Logger.Error("Invalid address {0}, please correct the site URL.", url);
+                throw;
+            }
+
+        }
     }
 }

NzbDrone.Web/Controllers/SettingsController.cs

@@ -391,8 +391,15 @@ namespace NzbDrone.Web.Controllers
                 _configProvider.FileSharingTalkUid = data.FileSharingTalkUid;
                 _configProvider.FileSharingTalkSecret = data.FileSharingTalkSecret;
 
+                try
+                {
                     if (data.NewznabDefinitions != null)
                         _newznabProvider.SaveAll(data.NewznabDefinitions);
+                }
+                catch(Exception)
+                {
+                    return JsonNotificationResult.Oops("Invalid Nzbnab Indexer found, please check your settings");
+                }
 
                 return GetSuccessResult();
             }