Return correct expiration

[bodgit]

The negotiated context attempts to indicate the expiration time of the context however it never seems to match reality. The TKEY record has an expiry field which will indicate validity for an hour yet after five minutes the negotiated context will cease to work.

Perhaps the expiry field in the TKEY record needs to be ignored and the expiration is buried in the negotiated GSSAPI/Kerberos/SSPI context.

[bodgit]

Just found in RFC 2930:

The inception and expiry times in a GSS-API mode TKEY RR are ignored.

I can probably simplify the code to just put 0 for these fields, but there still must be some sort of expiry time buried somewhere.

[bodgit]

Doesn't work if you set them to 0, the server refuses to deal. Interestingly I send a TKEY with an hour validity, I get back a TKEY with a whole day validity, yet it only seems to work for five minutes.