[RFC] proposal for new library: libosmo-net

[Pablo Neira Ayuso]

Hi,

After some private discussion with Harald, I'd like to propose one new
library to abstract the network interface that is used to communicate
two elements that are part of one GSM network (no matter if it's on
the A-bis interface, A interface, ...).

This new library, whose proposed name can be "libosmo-net", would
initially support:

- E1 interfaces.
- Ethernet + IPA TCP/IP.
- rs232 (as required by bs11 its config interface).

This support is included in libosmo-abis, so my idea is to extract
this code from it and leave in libosmo-abis only the specific A-bis
bits.

The libosmo-net library would be extensible, so we can add new
interfaces to it (new E1 cards supported, new protocols over BSD
sockets, and so on).

The interface provided to the client of the library will be homogeneous
for all supported interfaces (at least, as much as we can).

The new library will provide:

* a constructor/destructor to create/release some network interface of
* a given supported type.
* a call-back for receiving incoming messages that will take the
  actual msgb.
* one function for sending signalling messages.

As well as many helper functions in this regard.

Therefore, libosmo-abis will require this new libosmo-net library
after all is done.

For the A interface, I'd propose some hypothetical libosmo-a library
that will contain the specific A interface protocols.

Let me know what you think.