How to pass the Request.Body to the IsAuthenticWebhook method in Asp.Net Core 1.1

How do you use the ShopifyAuthorizationService.IsAuthenticWebhook method with a Stream?

I’m using ASP.NET Core 1.1. When passing the Resquest.Body from the controller action to the IsAuthenticWebhook I get a “NotSupportedException: Specified method is not supported” becuase the Stream doesn’t suppor the seek method. When you see the IsAuthenticWebhook’s source code, there is a inputStream.Position = 0; call but the stream doesn’t support it.

NotSupportedException: Specified method is not supported.

Microsoft.AspNetCore.Server.Kestrel.Internal.Http.FrameRequestStream.set_Position(long value)

[ernestogutierrez]

@nozzlegear thanks for taking time to solve this. As the post you shared says, there are two solutions, it could be replacing the stream or using the EnableRewind extension method.

So, using a custom middleware you can activate the seeking function of the stream, although I don’t know the implications of that.

In the startup.cs file we should add this: using Microsoft.AspNetCore.Http.Internal;

Next, in the Configure method of the Startup class before adding MVC and probably other middleware we have to add this:

app.Use(next => context => 
            {
                context.Request.EnableRewind();
                return next(context);
            });

Now, when calling IsAuthenticWebhook from a controller or probably from a action filter we can pass the Request.Body to the IsAuthenticWebhook without problems.

When I started to use ShopifySharp a year ago I was using another solution with ASP.NET WebApi, I didn’t like it but it worked in that moment. It was based on this post: Accepting Raw Request Body Content with ASP.NET Web API. I won’t use that solution anymore.

[clement911]

This is what I use:

var memoryStream = new MemoryStream();
            await Request.Body.CopyToAsync(memoryStream);
            bool isValidRequest = await AuthorizationService.IsAuthenticWebhook(Request.Headers, memoryStream, _shopifyLibOptions.SecretKey);
            if (!isValidRequest)
            {
                throw new UnauthorizedAccessException("This request is not an authentic webhook request.");
            }
            memoryStream.Position = 0;
            string body = new StreamReader(memoryStream).ReadToEnd();
            string topic = Request.Headers[ShopifyHelper.WEB_HOOK_TOPIC_NAME_HEADER].First();
            string shop = Request.Headers[ShopifyHelper.WEB_HOOK_SHOP_HEADER].First();
            string hmac = Request.Headers[ShopifyHelper.WEB_HOOK_HMAC_HEADER].First();
...