This patch adds support to set up a CBSP link so that osmo-cbc connects
as a TCP client to the BSC, which runs as a TCP server.
Similary, support to set up a SBc-AP link so that osmo-cbc connects
as a SCTP client to the MME, which runs as SCTP server.
A new "mode (client|server|disabled)" VTY command is added to use one
mother or the other, and also to disable the link and hence the peer
until it is set again. This is useful if the peer is under manintenance
for instance.
client sockets are created automatically when the "peer" vty node is
exited if the link is not yet created, hence creating it at startup or
if moved back from "disabled" mode. If client socket dies, it will
keep attempting reconnect every 5 seconds.
Related: OS#4945
Change-Id: I3ec54b615b41b56f7a9c64298e3fcaac37f4b60e
Rename osmo_*_cbc -> cbc_*_mgr:
Now they only hold TCP/SCTP server related conns, but will also hold
TCP/SCTP client conns in the near future.
Rename osmo_cbc_*_client -> cbc_*_link:
The term "client" is confusing, since it doesn't exist in CBSP/SBcAP,
and will later support connecting to server at TCP/SCTP level.
Let's use "link" instead, similar to what's used in osmo-bsc which
already supports both TCP client and server modes.
Change-Id: Ia9d26dc1593c8ee08dce348fe9f5f4c9398ea2a5