Link status.
If not zero, all attempts of filter_frame or request_frame
will fail with the corresponding code, and if necessary the reference
will be destroyed.
If request_frame returns an error, the status is set on the
corresponding link.
It can be set also be set by either the source or the destination
filter.
Link status. If not zero, all attempts of filter_frame or request_frame will fail with the corresponding code, and if necessary the reference will be destroyed. If request_frame returns an error, the status is set on the corresponding link. It can be set also be set by either the source or the destination filter.