Is there a way to set response headers for a webso...

# ktor

[Alexander Zhirkevich]

Is there a way to set response headers for a websocket route?

[Hristijan]

You can intercept the application send pipeline transformation and check if it's WebSocketUpgrade then append a header if that's what you asked

sendPipeline.intercept(ApplicationSendPipelne.Transform) { body -> if (body is WebSocketUpgrade) { call.response.headers. } }

Sorry for format it's from phone

Otherwise if you're trying to set a one that's predefined there's client.websocket(request lambda then you can add headers here)

client.webSocket(host, route, method, request = { header() }

[Alexander Zhirkevich]

> You can intercept the application send pipeline transformation and check if it's WebSocketUpgrade then append a header if that's what you asked
That might work but i have a library module that just provides custom route type on top of websockets so i dont think i have an access for pipline transformation. That route needs to add a Set-Cookie header for every websocket upgrade. There might be other websocket routes that have or have not to set this header. I'm not sure if it even possible to include cookies to the protocol upgrades
> client.webSocket( request = { header() }
I only need it for a ktor server responces

[Hristijan]

Maybe something like this

fun Route.customWebSocket(
path: String,
protocol: String,
handler: suspend DefaultWebScketServerSession.() -> Unit
) {
route(path) {
get {
call.response.cookies.append(
Cookie(
name =
value =
httpOnly =
Etc.)
call.respondWebSocketUpgrade(protocol, handler)
}
}
}

I'm still from phone so this is top of my head

[Hristijan]

Then you can use it as

route { customWebSocket("/ws") { handler }

[Aleksei Tirman [JB]]

You can use the following method to create a WebSockets route with the provided headers in the response for the upgrade request:

fun Route.webSocketWithHeaders(path: String, headers: Headers, block: suspend WebSocketServerSession.() -> Unit) {
    route(path) {
        header(HttpHeaders.Connection, "Upgrade") {
            header(HttpHeaders.Upgrade, "websocket") {
                get {
                    headers.forEach { name, values ->
                        call.response.headers.appendIfAbsent(name, values.joinToString(separator = ", "))
                    }

                    call.respond(WebSocketUpgrade(call, null, installExtensions = true, {
                        val session = toServerSession(call)
                        session.block()
                    }))
                }
            }
        }
    }
}

private fun WebSocketSession.toServerSession(call: ApplicationCall): WebSocketServerSession =
    DelegatedWebSocketServerSession(call, this)

private fun DefaultWebSocketSession.toServerSession(call: ApplicationCall): DefaultWebSocketServerSession =
    DelegatedDefaultWebSocketServerSession(call, this)

private class DelegatedWebSocketServerSession(
    override val call: ApplicationCall,
    val delegate: WebSocketSession
) : WebSocketServerSession, WebSocketSession by delegate

private class DelegatedDefaultWebSocketServerSession(
    override val call: ApplicationCall,
    val delegate: DefaultWebSocketSession
) : DefaultWebSocketServerSession, DefaultWebSocketSession by delegate

Here is how it can be used:

routing {
    webSocketWithHeaders("/ws", Headers.build {
        append(HttpHeaders.SetCookie, "name=value; path=/")
    }) {
        outgoing.send(Frame.Text("Hello World!"))
    }
}

[Alexander Zhirkevich]

Thanks. This one worked for me, a bit simpler:

fun Route.customRoute(path : String){

    route(path, HttpMethod.Get) {
        header(HttpHeaders.Connection, "Upgrade") {
            header(HttpHeaders.Upgrade, "websocket") {
                handle {
                    call.response.headers.append()
                }
            }
        }
    }

    webSocket(path) {
        // ...
    }
}