ken120-mvc-vuejs-CorsModule.cs

ken120-mvc-vuejs-CorsModule.cs

using System;
using System.Configuration;
using System.Linq;
using System.Web;

namespace CMS.Cors
{
    public class CorsModule : IHttpModule
    {
        private readonly string[] allowedOrigins;

        public CorsModule() =>
            allowedOrigins = ConfigurationManager
                .AppSettings["application:cors:allow-origin"]
                .Split(',');

        public void Init(HttpApplication context) =>
            context.BeginRequest += new EventHandler(Application_BeginRequest);

        public void Application_BeginRequest(object o, EventArgs ea)
        {
            var context = HttpContext.Current;

            var referrerUri = context.Request.UrlReferrer;

            if (referrerUri is null)
            {
                return;
            }

            string referrerOrigin = referrerUri.GetLeftPart(UriPartial.Authority);

            if (!allowedOrigins.Any(origin => string.Equals(origin, referrerOrigin, StringComparison.OrdinalIgnoreCase)))
            {
                return;
            }

            context.Response.Headers.Add("Access-Control-Allow-Origin", referrerOrigin);
            context.Response.Headers.Add("Access-Control-Allow-Credentials", "true");
            context.Response.Headers.Add("Access-Control-Allow-Methods", "GET");
            context.Response.Headers.Add("Access-Control-Allow-Headers", "Content-Type");
        }

        public void Dispose() { }
    }
}


/* How to use this module

Add the following to <system.webServer><modules>

     <add name="CORSModule" preCondition="managedHandler" type="CMS.Cors.CorsModule, CMSApp"/>

Add the following to <system.webServer>handlers>

    <remove name="ExtensionlessUrlHandler-Integrated-4.0" />
    <remove name="OPTIONSVerbHandler" />
    <remove name="TRACEVerbHandler" />

    <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />

Add the following entry to your AppSettings - the list is comma delimited

      <add key="application:cors:allow-origin" value="https://localhost:44397,https://localhost:44392,https://localhost:44391"/>

*/