[nat] Begin to patch SCCP connections

For the one MSC and n BSC case we need to patch the SCCP source
local reference on connection orientated links to avoid a clash.

For simple UDT packages we just let them pass and for SCCP connection
we have to:
    1.) Create an entry on Connection Request
    2.) Patch the entry on Connection Confirm, Connection Refuse,
        Connection Release, DT1, Connect Release Complete
    3.) Remove the entry on Connection Release Complete

The current code is blocking CRs, Release Complete from the MSC, and
creates the connection state only from the BSC side. The code to
assign a source reference is taken from sccp.c and handles wrap
arounds and such properly. We rely on the SCCP parser to fill out the
place to the source reference correctly so we can easily fix it.

The whole code is young and might contain bugs we need to resolve..
1 file changed
tree: a87ad86d21f56bc9fb68a3cff93b4e5f9423878c
  1. hlrsync/
  2. linux-kernel/
  3. openbsc/
  4. wireshark/