Content-Length wrong when IIndexHtmlTransformer transform html

[julien-vandenbussche]

Hello,

I am using AddFrontends for my application.
In my code, I use WithProxiedStaticAssets and define a custom IIndexHtmlTransformer. When running the application, I encounter the following exception:

"System.InvalidOperationException: Response Content-Length mismatch: too many bytes written...."

The exception is thrown in the file bff/src/Bff/DynamicFrontends/Internal/StaticFilesHttpClient.cs (line 109) because the Content-Length header is set at line 94 or 98 (identical instructions within a foreach loop).

To resolve this issue, I set the Content-Length header after the call to the IIndexHtmlTransformer's transformation method.

this original code:

var html = await transformer.Transform(html, frontend, ct);
await context.Response.WriteAsync(html ?? string.Empty, ct);
return;

my fix:

var html = await transformer.Transform(html, frontend, ct) ?? string.Empty;
context.Response.Headers.ContentLength = html.Length;
await context.Response.WriteAsync(html, ct);

I would like contributing, if it's possible.

DuendeSoftware/products@6a22a61

[Erwinvandervalk]

Thank you for reporting this. I've put it on the backlog to be picked up soon.

We don't take PR's to our products, but with your clear issue description the fix would be straigtforward.