common.h: clean out ip_addr stuff, add dns, prototypes
common.h: clean out ip_addr stuff, add dns, prototypes

TidyHuang/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor,TidyHuang/sdn_sensor,TidyHuang/sdn_sensor,TidyHuang/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,megahall/sdn_sensor,TidyHuang/sdn_sensor