Add config option to allow arbitrary domain names in endpoints
Connecting osmo-mgw to an SCCPlite MSC, I find the MSC issuing a CRCX on endpoint "email@example.com" (the IP address osmo-mgw is bound to)
osmo-mgw so far expects exactly one domain name, by default "@mgw", which is configurable.
The "proper" way to handle this would be to also make the domain name in osmo-bsc configurable, see #3489.
However, I am thinking, another route could be to simply not care about the domain name part on the osmo-mgw side, as a quick and dirty workaround.
Implementation wise, the easiest route to get osmo-bsc and osmo-mgw connected to the SCCPlite MSC is to simply not be strict about domain names.
If osmo-mgw ignored the domain name part, osmo-bsc would address "3@mgw" and the SCCPlite MSC "firstname.lastname@example.org", and both would mean "endpoint 3" without any apparent problems.
If I quickly hack the domain name check away, things carry on without much ado. It could be useful to allow this from a config option (that is off by default).
In my concrete situation, there is only one domain name sent by one MSC, but hypothetically, if the MGW were receiving several different domain names from separate clients that aren't easily configurable, ignoring the domain part could be useful.