Osmocom Libraries » libosmo-sccp + libosmo-sigtran

• When a SUA connection becomes active, the osmo_sua_* API should notify the SUA user with an
  N-STATE indication primitive with "User-in-service" information.
• When a connection is lost/closed, the same with "User-out-of-service" should be
  passed to the SUA user.

As discussed in this mail thread:
http://lists.osmocom.org/pipermail/openbsc/2016-April/008349.html

See OSMO_SCU_PRIM_N_STATE, osmo_sua_user_create() and its osmo_prim_cb parameter.

Notably, osmo_stream_* doesn't seem to have an on_disconnect cb, so it's not entirely
clear yet how to invoke the "User-out-of-service" prim.