[tor-dev] Modifying Path Selection based on geography

Hello there. I recently started to do some modifications on tor path selection by using stem, torflow/op-addon and txtorconn. but as long as i enable __LeaveStreamsUnattached option, tor will not function properly. so i decided to hack the source for this feature i seek: custom country for each position: entry:{{entry country-code}} middle:{{middle country-code}} exit:{{country-code}} i really appreciate you guys give me some hint, that which part of the source i must start to hack? i have dived into circuitbuild.c and some other core/or modules but i am confused where to start. thanks in advance.