Added the option to disable register

Moonlight/Core/Configuration/CoreConfiguration.cs

@@ -69,6 +69,10 @@ public class CoreConfiguration
         [JsonProperty("TokenDuration")]
         [Description("This specifies the duration the token of an user will be valid. The value specifies the days")]
         public int TokenDuration { get; set; } = 30;
+
+        [JsonProperty("DenyRegister")]
+        [Description("This disables the register function. No user will be able to sign up anymore. Its recommended to enable this for private instances")]
+        public bool DenyRegister { get; set; } = false;
     }
 
     public class SecurityData

Moonlight/Core/UI/Components/Auth/Register.razor

@@ -6,16 +6,28 @@
 @using Moonlight.Core.Models.Forms
 @using Moonlight.Core.Services
 @using MoonCore.Exceptions
+@using MoonCore.Services
 @using MoonCoreUI.Services
+@using Moonlight.Core.Configuration
 
 @inject IAuthenticationProvider AuthenticationProvider
 @inject IdentityService IdentityService
 @inject CookieService CookieService
 @inject NavigationManager Navigation
+@inject ConfigService<CoreConfiguration> ConfigService
 
 <div class="d-flex justify-content-center">
     <div class="d-flex align-items-center">
         <div class="card card-body m-15 p-15">
+            @if (ConfigService.Get().Authentication.DenyRegister)
+            {
+                <IconAlert Color="danger" Icon="bx-shield-quarter" Title="Sign up disabled">
+                    The administrator of this instance has disabled to sign up function<br />
+                    Back to <a href="/login">login</a>
+                </IconAlert>
+            }
+            else
+            {
                 <div class="text-center mb-8">
                     <div class="fw-bold mb-3 fs-1">
                         Register
@@ -57,6 +69,7 @@
                         </div>
                     </div>
                 </SmartForm>
+            }
         </div>
     </div>
 </div>
@@ -67,6 +80,9 @@
 
     private async Task OnValidSubmit()
     {
+        if (ConfigService.Get().Authentication.DenyRegister)
+            throw new DisplayException("The sign up function has been disabled");
+        
         if (Form.Password != Form.RepeatedPassword)
             throw new DisplayException("The passwords do not match");