How to implement http.Hijacker using Gorilla Websockets and alexedwards/scs/v2

php Editor Apple today introduces a method to implement http.Hijacker using Gorilla Websockets and the alexedwards/scs/v2 library. This method can help developers implement real-time communication functions in their own applications, whether it is a chat room or real-time updates, etc., can be implemented in this way. Next, we will explain in detail how to use these two libraries to implement http.Hijacker to make your application more powerful and flexible.

Question content

The excellent alexedwards/scs/v2 in Go web applications was recently upgraded from 2.5.0 to 2.7.0 to allow Go 1.20 to support http.NewResponseController(). Subsequently allow extension handler specific server write timeout for large file uploads. This is good. An unfortunate consequence of this necessary upgrade is the loss of websocket functionality, currently using Gorilla websockets v1.5.1 (latest). I'm getting a common error when trying to connect to upgrade... websocket: response not implemented http.Hijacker I've looked into a few threads for this, some of them on SO, but I haven't been able to resolve anything specific to this case. I've tried a few things to try and implement http.Hijacker in my websocket endpoint handler along with my other middleware code (commented out, attached "misleading" example for illustration)... I just think I understand this Not good enough. ..

type WebsocketConnection struct {
    *websocket.Conn
}

type WebsocketPayload struct {
    Action      string              `json:"action"`
    Message     string              `json:"message"`
    AdminName   string              `json:"admin_name"`
    MessageType string              `json:"message_type"`
    AdminID     int                 `json:"admin_id"`
    Connection  WebsocketConnection `json:"-"`
}

type WebsocketJSONResponse struct {
    Action        string   `json:"action"`
    Message       string   `json:"message"`
    AdminName     string   `json:"admin_name"`
    AdminID       int      `json:"admin_id"`
    CurrentLogins []string `json:"current_logins"`
}

var upgradeConnection = websocket.Upgrader{
    ReadBufferSize:  1024,
    WriteBufferSize: 1024,
    CheckOrigin:     func(r *http.Request) bool { return true },
}

var webClients = make(map[WebsocketConnection]string)

var websocketChannel = make(chan WebsocketPayload)

func (app *application) WebsocketEndPoint(w http.ResponseWriter, r *http.Request) {
    // rc := http.NewResponseController(w)
    // netConn, _, err := rc.Hijack()
    // if err != nil {
    //  app.errorLog.Println(err)
    //  return
    // }
    // defer netConn.Close()

    app.debugLog.Printf("w's type is %T\n", w)

    ws, err := upgradeConnection.Upgrade(w, r, nil)
    if err != nil {
        app.errorLog.Println(err)  <= ERROR HERE
        return
    }

    app.infoLog.Printf("Web client connected from %s", r.RemoteAddr)
    var response WebsocketJSONResponse
    response.Message = "Connected to server..."

    err = ws.WriteJSON(response)
    if err != nil {
        app.errorLog.Println(err)
        return
    }

    conn := WebsocketConnection{Conn: ws}
    webClients[conn] = ""

    go app.ListenForWebsocket(&conn)
}

The "w" in this example is *scs.sessionResponseWriter. How can I implement http.Hijacker in the response without breaking the connection and upgrading? What is the correct approach?

Workaround

alexedwards/scs/v2 package version 2.5.0 Supports hijacker interface. Version 2.7.0 does not support Hijacker interface, but supports Support response controller. The gorilla websocket package does not use response controllers.

Option 1

2.5.0 using alexedwards/scs/v2 package.

Option 2

Work around the gorilla package flaw by unpacking the response writer in the application code:

func (app *application) WebsocketEndPoint(w http.ResponseWriter, r *http.Request) {

    wupgrade := w
    if u, ok := w.(interface{ Unwrap() http.ResponseWriter }); ok {
        wupgrade = u.Unwrap()
    }

    app.debugLog.Printf("w's type is %T\n", w)

    ws, err := upgradeConnection.Upgrade(wupgrade, r, nil)
    if err != nil {
        app.errorLog.Println(err)
        return
    }

    app.infoLog.Printf("Web client connected from %s", r.RemoteAddr)
    var response WebsocketJSONResponse
    response.Message = "Connected to server..."

    err = ws.WriteJSON(response)
    if err != nil {
        app.errorLog.Println(err)
        return
    }

    conn := WebsocketConnection{Conn: ws}
    webClients[conn] = ""

    go app.ListenForWebsocket(&conn)
}

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