Sending compressed file (gzip) though HTTP messes with the encoding - http

Question

I have a compressed file.
How do I send it to the browser and make it decode it?
ASP.NET Core suports compression like this:
services.AddResponseCompression();
...
app.UseResponseCompresssion
app.Run(async (context) =>
{
var file = System.IO.File.ReadAllText("file.txt");
await context.Response.WriteAsync(file);
});
But my file is already compressed. I tried just setting the headers, reading the file and sending the content, but it messes with the encoding.
app.Run(async (context) =>
{
context.Response.Headers.Add("Content-Type", "text/plain");
context.Response.Headers.Add("Content-Encoding", "gzip");
context.Response.Headers.Add("Vary", "Accept-Encoding");
var file = System.IO.File.ReadAllText("compressed.gz");
await context.Response.WriteAsync(file);
});
If I just send the file, firefox and chrome try to download it, but do not decompress it.
Proof of that:
$ cat compressed.gz | hexdump | head -1
0000000 8b1f 0808 3768 5bc6 0302 6966 656c 742e
# that's the magic number: 8b 1f 08
$ curl -X GET http://localhost:5000/ -H 'Accept-Encoding: gzip' -H 'Cache-Control: no-cache' --output - | hexdump | head -1
0000000 ef1f bdbf 0808 3768 bfef 5bbd 0302 6966
How do I prevent encoding problems?

Answer 1

As #t.niese pointed out, the problem is reading the text by lines.
The proper way to do this task is to return a FileStreamResult
Example:
Response.Headers["Content-Encoding"] = "gzip";
return new FileStreamResult(new FileStream(fileName, FileMode.Open), "text/plain");