Where does the peer call golang's built in net.Dial to perform connection?

[FrontMage]

Hi, I'm trying to make a data channel based VPN with tunnel mode, in which all traffic will be routed to the VPN network interface for handling, thus I need to identify where the peer calls net.Dial and then mark the socket to not go to the VPN network iface.
After some reading and digging, I found out that dtls and sctp might be the place to do this, but it seems that the Dial in those places is not used in peer negotiation, so I went into the ICE repo, but I can't find where the peer does these connections, plz help, thx a lot!

[FrontMage]

I was trying to read the code from ice/transport.go from pion/ice but the dial is complete by using a custom connect method which does not call any net.DialUDP
After following the connect method, it seems the connection is already done by creating CandidatePair, but the CandidatePair's connection comes from a net.ListenUDP not any dial, so I'm kind of confused.