Proper way to share code between several modules

Hi there I wrote several modules which share similar logic and the same DB backend. Right now I'm using a source file for this purpose which is included in every module's SOURCES variable (all.mk). I don't like this approach very much. But are there better alternatives? I could add the shared code as a library. But it uses Freeradius functions, so I had to build it somewhere in the Freeradius source tree... At this point I am overwhelmed with my little knowledge... Best regards, Till