Using AdvantageApiCorsPolicyProvider to Manage CORS Policies
This guide explains how to use the to manage Cross-Origin Resource Sharing (CORS) policies in API endpoints by dynamically configuring allowed origins.
Developers can implement this by decorating their API controllers or specific actions with the attribute.
public class MyCorsPolicyProvider : AdvantageApiCorsPolicyProviderBase
{
public override async Task<CorsPolicy> GetCorsPolicyAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
var policy = new CorsPolicy
{
AllowAnyHeader = true,
AllowAnyMethod = true,
SupportsCredentials = true
};
if (request.Headers.Contains("Origin"))
{
var origins = GetAllowedOrigins();
if (orgins!=null){
foreach (var origin in origins)
policy.Origins.Add(origin);
}
}
return policy;
}
private IEnumerable<string> GetAllowedOrigins()
{
var originsConfig = System.Configuration.ConfigurationManager.AppSettings["AllowedOrigins"];
return !string.IsNullOrEmpty(originsConfig) ? originsConfig.Split(',') : null;
}
}
[AdvantageApiCorsPolicy(typeof(MyCorsPolicyProvider))] public class SecureController : AdvantageApiControllerBase { public IHttpActionResult GetSecureData() { return Ok("Access granted to secure data."); } }
The EXAMPLE CORS policy ensures that only the allowed origins can access the API, based on the values specified in the Web.config. Below is an example implementation of how the allowed origins are retrieved and applied to the CORS policy:
<appSettings> <add key="AllowedOrigins" value="https://example.com, https://anotherdomain.com" /> </appSettings>
This configuration ensures that only requests from the specified origins are allowed to access your API, improving security by preventing unauthorized access.