Suggested partual fix - add this possible value for o_cancel:
#define SLAP_CANCEL_INVALID 0x04 /* like 0 but prevents Cancel */
Something like this:
Does not reject abandon(Cancel/StartTLS), would need to extend o_cancel
with yet another value. That's ugly enough already, so I let that wait.
connection_abandon() in particular isn't invalid client action, but it
shouldn't be worse than causing a surprising result code or not response
before closing the connection.
Does not address syncprov's Cancel handler.
I don't know if the bconfig.c pathces are correct, but need to reject
cancel before (reacting to) thread pool pauses there and maybe in