gskit: remove unused function set_callback

[danielgustafsson]

This function has been unused since the initial commit of the GSKit backend in 0eba02f. @monnerat, am I missing something?

[monnerat]

You're right, it's unused.

My motivation for it was getting the whole certificate chain: the only place where the latter is available is as a callback parameter and I planned to get the certs from there.

Unfortunately this is not possible to pass a user pointer to this callback, effectively precluding the possibility to associate the cert chain with a data/conn structure.

There's a comment about it at

curl/lib/vtls/gskit.c

Lines 1070 to 1074 in a7b2912

	/* The only place GSKit can get the whole CA chain is a validation
	callback where no user data pointer is available. Therefore it's not
	possible to copy this chain into our structures for CAINFO.
	However the server certificate may be available, thus we can return
	info about it. */

.

See also https://www.ibm.com/docs/api/v1/content/ssw_ibm_i_71/apis/gsk_attribute_set_callback.htm and search for pgsk_cert_validation_callback on the page.

I kept the function around in hope IBM would add such a parameter but they never did. 9 years later, I'm convinced they'll never do thus we'll never have the whole chain in CAINFO and I approve this removal.

Thanks for looking at it.

[danielgustafsson]

Thanks for clarifying!