Golang shuts down listener network

I am having trouble closing the listener so that I can reopen it on the same port. I am writing a proxy that is hot configured - what it does (redirects / blocks, etc) can be configured on the fly. The proxy server works in a routine. The problem I am facing is that when I reconfigured the listener and proxy, the listener is still using that port from the previous configuration. (FYI listener is a global pointer) I am trying something like:

to kill the listener:

func KillProxy() {

    if listener != nil {
        log.Println(" *** TRYING TO STOP THE PROXY SERVER")
        (*listener).Close()
        listener = nil
    }
}

      

        
        
        
      

    

before reconfiguring it like this:

log.Println("listener (S1): ", listener)
if listener == nil {
    // Start the listener to listen on the connection.
    l, err := net.Listen(CONN_TYPE, CONN_HOST + ":" + CONN_PORT)

    if err != nil {
        log.Println("error here: ", err)
    }    
    listener = &l //set it as a pointer to the newly created listener
} 
log.Println("listener (S2): ", listener)

      

        
        
        
      

    

however, it doesn't seem to work - I get the error:

listener (S1):

here: listen tcp 0.0.0.0:8080: bind: address is already in use

listener (S2): 0xc2080015e0

and then a massive stack trace that adds up to:

panic: runtime error: invalid memory address or pointer spread to zero

CHANGE ANSWER TO JIM:

Interesting re-pointers. OK. I am not working while waiting for the socket to close, I am not sure how this should be done. The proxy library I'm using is this: https://github.com/abourget/goproxy . Things happen:

KillProxy()
refreshProxy()

      

        
        
        
      

    

refreshProxy stores the above code that tries to repurpose the listener. The last thing that happens in refreshProxy()

:

go http.Serve(*listener, proxy)

So, if I return to the listener as a global variable rather than a pointer, I can do KillProxy ():

func KillProxy() {
    if listener != nil {
        listener.Close()
        listener = nil
    }
}

      

        
        
        
      

    

and then set up the listener again like

listener, err := net.Listen(CONN_TYPE, CONN_HOST + ":" + CONN_PORT) 
    if err != nil {
        log.Println("error here: ", err)
    }    

      

        
        
        
      

    

However, I don't know how to wait and check if the socket is closed before trying to create a listener object?