MireaBackend/Endpoint/Common/Attributes/LocalhostAttribute.cs

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using System;
using System.Net;

namespace Mirea.Api.Endpoint.Common.Attributes;

public class LocalhostAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext context)
    {
        var ip = context.HttpContext.Connection.RemoteIpAddress;

        if (ip == null)
        {
            context.Result = new UnauthorizedResult();
            return;
        }

        var isRunningInContainer = Environment.GetEnvironmentVariable("DOTNET_RUNNING_IN_CONTAINER")?.ToLower() == "true";

        if (IPAddress.IsLoopback(ip) || (isRunningInContainer && ip.ToString().StartsWith("172.")))
        {
            base.OnActionExecuting(context);
            return;
        }

        context.Result = new UnauthorizedResult();
    }
}