dial.go
func (d *Dialer) rawConnDial(ctx context.Context, raddr ma.Multiaddr, remote peer.ID) (transport.Conn, error) {
	if strings.HasPrefix(raddr.String(), "/ip4/0.0.0.0") {
		log.Event(ctx, "connDialZeroAddr", lgbl.Dial("conn", d.LocalPeer, remote, nil, raddr))
		return nil, fmt.Errorf("Attempted to connect to zero address: %s", raddr)
	}

	sd := d.subDialerForAddr(raddr)
	if sd == nil {
		return nil, fmt.Errorf("no dialer for %s", raddr)
	}

	return sd.DialContext(ctx, raddr)
}
func (d *Dialer) rawConnDial(ctx context.Context, raddr ma.Multiaddr, remote peer.ID) (transport.Conn, error) {
	if strings.HasPrefix(raddr.String(), "/ip4/0.0.0.0") {
		log.Event(ctx, "connDialZeroAddr", lgbl.Dial("conn", d.LocalPeer, remote, nil, raddr))
		return nil, fmt.Errorf("Attempted to connect to zero address: %s", raddr)
	}

	sd := d.subDialerForAddr(raddr)
	if sd == nil {
		return nil, fmt.Errorf("no dialer for %s", raddr)
	}

	return sd.DialContext(ctx, raddr)
}
// rawConnDial dials the underlying net.Conn + manet.Conns