Hi all,

we have recently merged a profound change to the inner workings of the VTY configuration. We've hit some fallout due to that, hence I would like to let you know that you might hit the same.

The VTY parsing of config files is now strict about indenting. A child node *must* be indented below the parent node, and indenting must be consistent.

For more details on the reason why and a definition of 'consistent', see the commit log of https://git.osmocom.org/libosmocore/commit/?id=4a31ffa2f0097d96201f80305a049...

So, if you are in the near future faced with config files being rejected that worked perfectly before, it is most probably because your indenting was wrong all the time, and only now did we start checking it.

If the cause is hard to figure out, a good aid is the telnet VTY, where you may either 'show running-config' or traverse the nodes manually to query which command exists on which level. If your current config is broken, you may be able to start the program with an empty or stripped down config file to make its telnet available.

The above is about reading config files, but we have also dropped the implicit 'exit' to parent level on the telnet VTY console. This caused fallout where nodes by plain omission lack the 'exit' command: one is unable to leave such a node once it is entered. That is a fault in the program's VTY setup that was not found before, because the VTY would often just find the parent node's exit command instead. I have a patch to avoid all of these everywhere, by installing the exit and end commands automatically for every VTY node that gets created; it is not merged yet: https://gerrit.osmocom.org/3998

------ Config Fallout Example ------

For example, we hit a breakage with this osmo-bts-trx.cfg:

phy 0 instance 0 osmotrx rx-gain 25 osmotrx tx-attenuation oml osmotrx ip local 10.23.42.1 osmotrx ip remote 10.23.42.2

Before, this worked perfectly. Now it says the command 'osmotrx rx-gain' does not exist. The reason is that 'osmotrx rx-gain' is a child node of 'instance 0'. The first fix looked like this:

phy 0 instance 0 osmotrx rx-gain 25 osmotrx tx-attenuation oml osmotrx ip local 10.23.42.1 osmotrx ip remote 10.23.42.2

But alas, this time it said the command 'osmotrx ip local' does not exist. I suspected bugs in the new parsing, but indeed, 'osmotrx ip' is actually a direct child of the 'phy 0' level. Before, the VTY would implicitly step out of a child level if it found a matching command one parent above. That is confusing in other situations (see above commit log), hence we now require indenting to clarify the structure. This is the correct one:

phy 0 instance 0 osmotrx rx-gain 25 osmotrx tx-attenuation oml osmotrx ip local 10.23.42.1 osmotrx ip remote 10.23.42.2

Or rephrased:

phy 0 osmotrx ip local 10.23.42.1 osmotrx ip remote 10.23.42.2 instance 0 osmotrx rx-gain 25 osmotrx tx-attenuation oml

To query the structure via telnet, I did:

$ ./osmo-bts/src/osmo-bts-trx/osmo-bts-trx -c osmo-bts/doc/examples/trx/osmo-bts.cfg

$ telnet localhost 4241 OsmoBTS> enable OsmoBTS# configure terminal OsmoBTS(config)# phy 0 OsmoBTS(phy)# list [...] osmotrx ip HOST osmotrx ip (local|remote) A.B.C.D [...] OsmoBTS(phy)# inst OsmoBTS(phy)# instance 0 OsmoBTS(phy-inst)# list [...] osmotrx rx-gain <0-50> osmotrx tx-attenuation <0-50> osmotrx tx-attenuation oml [...]

------ No Exit Example ------

The same osmo-trx VTY nodes also show the exit failure:

$ telnet localhost 4241 OsmoBTS> enable OsmoBTS# configure terminal OsmoBTS(config)# phy 0 OsmoBTS(phy)# exit % Unknown command. OsmoBTS(phy)# instance 0 OsmoBTS(phy-inst)# exit % Unknown command.

On the phy level, we would previously find the parent's 'exit' command, but in the 'instance' level, 'exit' has never been available. Above patch should fix all of these.

~N