Handling 404s in my remote image provider

[skttl]

I've created a provider for fetching images over http (https://github.com/skttl/ImageSharpCommunity.Providers.Remote/).

From time to time I run in to a problem where bots or users are requesting images that simply doesn't exist. Eg. /remote/nonexisting.com/404.jpg.

This returns a 500 error, since the stream returned in https://github.com/skttl/ImageSharpCommunity.Providers.Remote/blob/main/src/ImageSharpCommunity.Providers.Remote/RemoteImageResolver.cs#L47 doesn't contain an image.

I would love if I could return a 404 from here, but the only possible solution I can think if, is by adding a request in the provider (https://github.com/skttl/ImageSharpCommunity.Providers.Remote/blob/main/src/ImageSharpCommunity.Providers.Remote/RemoteImageProvider.cs#L43) to check if the url returns anything.

But I think that would make it do that request every time the image is requested from /remote/nonexisting.com/404.jpg, and also when requesting images that actually exists. Doing the request for images we "don't know" yet is not a problem, we do it anyway in the resolver. But having that request each and every time a "known" image, that might already be in the ImageSharp.Web cache feels wrong.

Am I wrong, or is there a better way of doing this?

[JimBobSquarePants]

You could do a HEAD request. That way you avoid the full download but get whatever info you need.

[JimBobSquarePants]

You should also be locking down your requests with HMAC.

[skttl]

Yes, I thought that too. But still, a request for every request to the image feels wrong, maybe I can cache it...

HMAC sounds like a good idea, need to read up on that!

[skttl]

I added a request (with caching according to response headers) in the provider > skttl/ImageSharpCommunity.Providers.Remote#4

Seeking advice, if I should worry about anything for this?

[JimBobSquarePants]

I'll have a look when I have some downtime