After a rekeying the outbound SA and policy is deleted immediately, however,
the inbound SA is not removed until a few seconds later, so delayed packets
can still be processed.
This adds a flag to get_esa_id() that specifies the location of the
given SPI.
The main difference is that ping now reports icmp_seq instead of
icmp_req, so we match for icmp_.eq, which works with both releases.
tcpdump now also reports port 4500 as ipsec-nat-t.
This test asserts that the handling of XFRM expire messages from the
kernel are handled correctly by the xfrm-proxy and the Esa Event Service
(EES) in charon-tkm.
