tree 0d00b16a3d42ce2c8ed9df6014f7ebf444d17349
parent a75d1c2c94bc45ee051a07563e633bfb9911dc52
author Neels Hofmeyr <neels@hofmeyr.de> 1574217337 +0100
committer Neels Hofmeyr <neels@hofmeyr.de> 1588078435 +0200

D-GSM 3/n: implement roaming by mslookup in osmo-hlr

Add mslookup client to find remote home HLRs of unknown IMSIs, and
proxy/forward GSUP for those to the right remote HLR instances.

Add remote_hlr.c to manage one GSUP client per remote HLR GSUP address.

Add proxy.c to keep state about remotely handled IMSIs (remote GSUP address,
MSISDN, and probably more in future patches).  The mslookup_server that
determines whether a given MSISDN is attached locally now also needs to look in
the proxy record: it is always the osmo-hlr immediately peering for the MSC
that should respond to mslookup service address queries like SIP and SMPP.
(Only gsup.hlr service is always answered by the home HLR.)

Add dgsm.c to set up an mdns mslookup client, ask for IMSI homes, and to decide
which GSUP is handled locally and which needs to go to a remote HLR.

Add full VTY config and VTY tests.

For a detailed overview of the D-GSM and mslookup related files, please see the
elaborate comment at the top of mslookup.c (already added in an earlier patch).

Change-Id: I2fe453553c90e6ee527ed13a13089900efd488aa