New: Setting to disable authentication for local addresses

(cherry picked from commit b154b00c6156512e7fbd0a2c4833c116a74f23ca)

src/Sonarr.Http/Authentication/UiAuthorizationHandler.cs

@@ -0,0 +1,45 @@
+using System.Net;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Http;
+using NzbDrone.Common.Extensions;
+using NzbDrone.Core.Authentication;
+using NzbDrone.Core.Configuration;
+using NzbDrone.Core.Configuration.Events;
+using NzbDrone.Core.Messaging.Events;
+using Sonarr.Http.Extensions;
+
+namespace NzbDrone.Http.Authentication
+{
+    public class UiAuthorizationHandler : AuthorizationHandler<BypassableDenyAnonymousAuthorizationRequirement>, IAuthorizationRequirement, IHandle<ConfigSavedEvent>
+    {
+        private readonly IConfigFileProvider _configService;
+        private static AuthenticationRequiredType _authenticationRequired;
+
+        public UiAuthorizationHandler(IConfigFileProvider configService)
+        {
+            _configService = configService;
+            _authenticationRequired = configService.AuthenticationRequired;
+        }
+
+        protected override Task HandleRequirementAsync(AuthorizationHandlerContext context, BypassableDenyAnonymousAuthorizationRequirement requirement)
+        {
+            if (_authenticationRequired == AuthenticationRequiredType.DisabledForLocalAddresses)
+            {
+                if (context.Resource is HttpContext httpContext &&
+                    IPAddress.TryParse(httpContext.GetRemoteIP(), out var ipAddress) &&
+                    ipAddress.IsLocalAddress())
+                {
+                    context.Succeed(requirement);
+                }
+            }
+
+            return Task.CompletedTask;
+        }
+
+        public void Handle(ConfigSavedEvent message)
+        {
+            _authenticationRequired = _configService.AuthenticationRequired;
+        }
+    }
+}