private static async Task SendFileToResponse(OwinResponse response, CrossAppDomainResponseFile file) {
if(response.CanSendFile)
{
await response.SendFileAsync(file.Path, file.Length, file.Offset, CancellationToken.None);
return;
}
var buffer = new byte[file.Length - file.Offset];
using (var stream = File.OpenRead(file.Path)) {
stream.Seek(file.Offset, SeekOrigin.Begin);
await stream.ReadAsync(buffer, 0, (int)file.Length);
}
await response.WriteAsync(buffer);
}