How Does Openssh Implement Local Port Forward?

I started a sshd(using go-ssh) to listen ssh-client,

and run ssh -L 2345:127.0.0.1:5244 127.0.0.1 -p 2022 -N.

I didn't receive any message from client (include "direct-tcpip" ), but I can access web through 127.0.0.1:2345.

How does OpenSSH implement local port forward?

I hope than I can receive "direct-tcpip" from client.

sshConn, ch, globalRequestCh, err := ssh.NewServerConn(conn, config)
    if err != nil {
        log.Println("Handshake  err", err)
        return
    }

    log.Println("sshd serving", "ssh client", sshConn.RemoteAddr())

        
    go func() {
    // handle newChan
    for newChannel := range ch {
        log.Println("new channel", "type", newChannel.ChannelType())
        switch newChannel.ChannelType() {
        case "session":
                    
        case "direct-tcpip":
                    
        default:

            }
    }
    }()

    // handle globalRequest
    for globalRequest := range globalRequestCh {
    log.Println("global request", "type", globalRequest.Type)
    switch globalRequest.Type {
        case "tcpip-forward":

        case "cancel-tcpip-forward":

        default:
    
        }
    }