Stripping the calling station id

Hello, Could someone help me to strip the calling station id recieved in the request to use it later for the checkval module. I am applying the mac authentication using checkval but the problem is that I am recieving a long calling station id containing the mac address. this is an exemple of the calling station id recieved : lag-50:1201.0#BNG Kasbah###pppoe 94:a7:b7:3e:93:5b# its always in this format and I only want to extract the mac address from it. I dont know if it can be achieved using unlang or anything else.