I started to play with smalltalk somewhere in February, more specific with the GNU Smalltalk implementation. Like it is with any new language and class library it takes a while to get productive and it took me until somewhere the last month where I finally started to do GSM handling in Smalltalk and thanks to laf0rge the code is now in a public repository and hosted along the other Osmocom projects. You can see all the subprojects over here.

So far I can create and parse the ipaccess IPA protocol, SCCP, BSSAP, BSSMAP and messages for Call Control and Mobility Management of GSM48. I also have a small Web-UI to connect to a MSC and then do a Location Updating Request and a Mobile Originated Call for a configurable IMSI (you will need to know your AuKey for that). It is very easy to parse and create the whole stack of messages, adding new GSM48 messages is easy as well (i still consider writing a program to get this directly from the GSM48 PDF).

This code is probably very well suited to do load tests of a MSC, e.g. find out how many LUs it can do a second, also to play easily with various quirks with it. Thanks to the nature of smalltalk one can easily change the creation of messages at runtime without needing to reconnect to the MSC. The next thing would probably to use it for fuzzing a MSC…

One note of caution, it is my first Smalltalk project and there are probably plenty of things I do wrong, I already know some of them and will work on refactoring it to a better structure. The next stop is nice ASN1 support, I will base it on the LDAP work.