Resolve Contributors

You can implement you own custom resolver contributors (for the client id and/or IP) via the RateLimitConfiguration class:

public class RateLimitConfiguration : IRateLimitConfiguration
{
        
    protected virtual void RegisterResolvers()
    {
        if (!string.IsNullOrEmpty(ClientRateLimitOptions?.ClientIdHeader))
        {
            ClientResolvers.Add(new ClientHeaderResolveContributor(HttpContextAccessor, ClientRateLimitOptions.ClientIdHeader));
        }

        // the contributors are resolved in the order of their collection index
        if (!string.IsNullOrEmpty(IpRateLimitOptions?.RealIpHeader))
        {
                IpResolvers.Add(new IpHeaderResolveContributor(HttpContextAccessor, IpRateLimitOptions.RealIpHeader));
        }

        IpResolvers.Add(new IpConnectionResolveContributor(HttpContextAccessor));
    }
}

There are some predefined resolve contributors:

• IpConnectionResolveContributor - gets the IP from the HttpContext.Connection.RemoteIpAddress property

• IpHeaderResolveContributor - gets the IP from the HTTP header named via the RealIpHeader application setting - can be used if the application is hosted behind a proxy

• ClientHeaderResolveContributor - gets the Client Id from the HTTP header named via the ClientIdHeader application setting

You can define your own contributor by implementing the IClientResolveContributor interface (that for example parses the query string to get the Client Id) and add it to the configuration:

public class CustomRateLimitConfiguration : RateLimitConfiguration
{
    protected override void RegisterResolvers()
    {
    	base.RegisterResolvers();

    	ClientResolvers.Add(new ClientQueryStringResolveContributor(HttpContextAccessor, "queryStringParamName"));
    }
}

Then, you just need to add it to the dependency container:

services.AddSingleton<IRateLimitConfiguration, CustomRateLimitConfiguration>();