Non-DNS data is cached in the BuilderAdapter so the TUN device can be
recreated easily (since the CHILD_SA is gone we couldn't actually gather
that information).
This class proxies DNS requests over VPN-protected UDP sockets.
It is not really Android specific and might be useful for
kernel-libipsec or libipsec in general too, so we could maybe move it later
to libipsec (might need some portability work).
No matter what triggers it. We also don't close the TUN device, but we
might handle that differently in the future to allow reestablishing the
IKE_SA if host names have to be re-resolved via DNS.
Replace the allowany semantic by a more powerful subnet and IP range matching.
Multiple addresses, DNS names, subnets and ranges can be specified in a comma
separated list. Initiators ignore the ranges/subnets, responders match
configurations against all addresses, ranges and subnets.
This new flag gives the kernel-interface a hint how it should priorize the
use of newly installed SAs during rekeying.
Consider the following rekey procedure in IKEv2:
Initiator --- Responder
I1 -------CREATE-------> R1
I2 <------CREATE--------
-------DELETE-------> R2
I3 <------DELETE--------
SAs are always handled as pairs, the following happens at the SA level:
* Initiator starts the exchange at I1
* Responder installs new SA pair at R1
* Initiator installs new SA pair at I2
* Responder removes old SA pair at R2
* Initiator removes old SA pair at I3
This makes sure SAs get installed/removed overlapping during rekeying. However,
to avoid any packet loss, it is crucial that the new outbound SA gets
activated at the correct position:
* as exchange initiator, in I2
* as exchange responder, in R2
This should guarantee that we don't use the new outbound SA before the peer
could install its corresponding inbound SA.
The new parameter allows the kernel backend to install the new SA with
appropriate priorities, i.e. it should:
* as exchange inititator, have the new outbound SA installed with higher
priority than the old SA
* as exchange responder, have the new outbound SA installed with lower
priority than the old SA
While we could split up the SA installation at the responder, this approach
has another advantage: it allows the kernel backend to switch SAs based on
other criteria, for example when receiving traffic on the new inbound SA.
Tobias Brunner