[PATCH] sysmobts: Deal with ciphering when we have a transport clash

[Harald Welte]

Hi Holger,

the patches look fine to me, although it hurts that such a hack and
layering violations is actually needed. I'm wondering if the spec
designers didn't come up with a more elegant method.

In OpenBSC we could of course disable early classmark sending, but we
cannot exclude osmo-bts / sysmobts from being used with other
implementations either.

What about OpenBSC waiting for the classmark change to arrive _if_ early
classmark sending is enabled? At least, if A5/4 is ever used, this is
the only way to support it anyway, as A5/4 is indicated only in CM3, and
CM3 is only part of CLASSMARK CHANGE, but not part of the CM SERVICE
REQUEST or PAGING RESPONSE.

However, as we are probably all quite sure that the GSM industry is not
capable of rolling out a 'new' cipher in less than 10 years, I'm not
sure if we should worry about this here.