need callback for each internal requests

[hbakhtiyor]

how many internally call http requests? if file exists one head request, is it only this call? or have another?
i need to get header ("auth") of the head request and set new one on next request.

any apis to achieve this?

[cavaliercoder]

This is currently not possible but something I should consider.
Alternatively, you can perform the head request yourself first and then populate a grab request.

[hbakhtiyor]

how to disable internal additional head requests?

[cavaliercoder]

You can disable grab's HEAD requests by setting Request.NoResume = true. Naturally, this will also prevent grab from being able to resume incomplete downloads.

If you want both features, you will need three request:

• first you send a HEAD request to get the auth header
• second, grab will send HEAD request to determine file size, resume-ability, etc.
• last, grab will send GET request to download the file

If your program is not particularly latency sensitive, this additional HEAD request seem inexpensive to me.