[strongSwan] IKE retransmission counters

[Martin Willi]

> Where to register the listeners for these alerts ? Any pointers will be
> greatly appreciated. 

If you want to extend the listcounters functionality, catch
ALERT_RETRANSMIT_SEND and or RECEIVE in the stroke_counters listener
hook [1]. Introduce appropriate counters analogue to those existing.

If you want to register your own plugin, use the same class as
reference.

Regards
Martin

[1]http://git.strongswan.org/?p=strongswan.git;a=blob;f=src/libcharon/plugins/stroke/stroke_counter.c;hb=HEAD#l151