How to implement "Access-Control-Allow-Origin" header in asp.net

Question

Is it possible to implement "Access-Control-Allow-Origin" header in asp.net

Impulsion

Answer 1

From enable-cors.org:

CORS on ASP.NET

If you don't have access to configure IIS, you can still add the header through ASP.NET by adding the following line to your source pages:

Response.AppendHeader("Access-Control-Allow-Origin", "*");

See also: Configuring IIS6 / IIS7

Mollymollycoddle

+1 Thanks, But I need to add this header only for resource files e.g. css & js files – Impulsion

I have some js files which are frequently updated and i want to use them on other domain, but they wont work coz cross domain policy – Impulsion

Anyways I'll add this to whole site – Impulsion

How do you add it to the resource files? – Garling

At me, in the current version of c#, the accepted syntax was Response.Headers.Add("Access-Control-Allow-Origin", "*"); – Mecke

Answer 2

Another option is to add it on the web.config directly:

<system.webServer>
    <httpProtocol>
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="http://www.yourSite.com" />
        <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS"/>
        <add name="Access-Control-Allow-Headers" value="Origin, X-Requested-With, Content-Type, Accept" />
      </customHeaders>
    </httpProtocol>

... I found this in here

Coombs

Is there a reason setting the value to a URL instead of a * doesn't work with json calls? – Sclerophyll

Answer 3

1.Install-Package Microsoft.AspNet.WebApi.Cors

2 . Add this code in WebApiConfig.cs.

public static void Register(HttpConfiguration config)
{
    // Web API configuration and services

    // Web API routes

    config.EnableCors();

    config.MapHttpAttributeRoutes();

    config.Routes.MapHttpRoute(
        name: "DefaultApi",
        routeTemplate: "api/{controller}/{id}",
        defaults: new { id = RouteParameter.Optional }
    );
}

3. Add this

using System.Web.Http.Cors; 

4. Add this code in Api Controller (HomeController.cs)

[EnableCors(origins: "*", headers: "*", methods: "*")]
public class HomeController : ApiController
{
    [HttpGet]
    [Route("api/Home/test")]
    public string test()
    {
       return "";
    }
}

Gouda

this code allows CORS on specific action method and not a js file – Impulsion

Answer 4

You would need an HTTP module that looked at the requested resource and if it was a css or js, it would tack on the Access-Control-Allow-Origin header with the requestors URL, unless you want it wide open with '*'.

Japan

Answer 5

Configuring the CORS response headers on the server wasn't really an option. You should configure a proxy in client side.

Sample to Angular - So, I created a proxy.conf.json file to act as a proxy server. Below is my proxy.conf.json file:

{
  "/api": {
    "target": "http://localhost:49389",
    "secure": true,
    "pathRewrite": {
      "^/api": "/api"
    },
    "changeOrigin": true
  }
}

Put the file in the same directory the package.json then I modified the start command in the package.json file like below

"start": "ng serve --proxy-config proxy.conf.json"

now, the http call from the app component is as follows:

return this.http.get('/api/customers').map((res: Response) => res.json());

Lastly to run use npm start or ng serve --proxy-config proxy.conf.json

Emma