Only accept change cipher spec when it is expected instead of at any
time. This prevents premature setting of session keys before the master
secret is determined which an attacker could use as a MITM attack.
Thanks to KIKUCHI Masashi (Lepidum Co. Ltd.) for reporting this issue
and providing the initial fix this patch is based on.
(Imported from upstream's 77719aefb8f549ccc7f04222174889615d62057b)
This patch removes support for empty records (which is almost
universally disabled via SSL_OP_ALL) and adds optional support for 1/n-1
record splitting.
The latter is not enabled by default, since it's not typically used on
servers, but it should be enabled in web browsers since there are known
attacks in that case (see BEAST).
Limit the number of empty records that will be processed consecutively
in order to prevent ssl3_get_record from never returning.
Reported by "oftc_must_be_destroyed" and George Kadianakis.
Initial fork from f2d678e6e89b6508147086610e985d4e8416e867 (1.0.2 beta).
(This change contains substantial changes from the original and
effectively starts a new history.)
