Enable CORS for Web API 1, .net 4.0

Question

I need to enable CORS for my Web API and I can\'t upgrade to Framework 4.5 at the moment. (I know about System.Web.Http.Cors.EnableCorsAttribute.)

I\'ve tried to add

Answer 1

I had faced the lot of issue with webAPI 1 Cross domain access finally able to fix it have a look at my blog http://keerthirb.blogspot.in/2017/08/making-cross-enable-for-webapi1.html

Cross code is

public class CorsHandler : DelegatingHandler
{
    const string Origin = "Origin";
    const string AccessControlRequestMethod = "Access-Control-Request-Method";
    const string AccessControlRequestHeaders = "Access-Control-Request-Headers";
    const string AccessControlAllowOrigin = "Access-Control-Allow-Origin";
    const string AccessControlAllowMethods = "Access-Control-Allow-Methods";
    const string AccessControlAllowHeaders = "Access-Control-Allow-Headers";

    protected override Task SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        bool isCorsRequest = request.Headers.Contains(Origin);
        bool isPreflightRequest = request.Method == HttpMethod.Options;
        if (isCorsRequest)
        {
            if (isPreflightRequest)
            {
                return Task.Factory.StartNew(() =>
                {
                    HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);
                    response.Headers.Add(AccessControlAllowOrigin, request.Headers.GetValues(Origin).First());

                    string accessControlRequestMethod = request.Headers.GetValues(AccessControlRequestMethod).FirstOrDefault();
                    if (accessControlRequestMethod != null)
                    {
                        response.Headers.Add(AccessControlAllowMethods, accessControlRequestMethod);
                    }

                    string requestedHeaders = string.Join(", ", request.Headers.GetValues(AccessControlRequestHeaders));
                    if (!string.IsNullOrEmpty(requestedHeaders))
                    {
                        response.Headers.Add(AccessControlAllowHeaders, requestedHeaders);
                    }

                    return response;
                }, cancellationToken);
            }
            else
            {
                return base.SendAsync(request, cancellationToken).ContinueWith(t =>
                {
                    HttpResponseMessage resp = t.Result;
                    resp.Headers.Add(AccessControlAllowOrigin, request.Headers.GetValues(Origin).First());
                    return resp;
                });
            }
        }
        else
        {
            return base.SendAsync(request, cancellationToken);
        }
    }
}