Safari: failed to write data frame: WebSocket closed: received close frame: status = StatusProtocolError and reason = ""

[andig]

I have an application that I'm migrating from gorilla/websocket to nhooyr. Changing the code is straightforward based on the chat example. This is the core send loop:

func (h *SocketHub) subscribe(ctx context.Context, conn *websocket.Conn) error {
	ctx = conn.CloseRead(ctx)

	s := &socketSubscriber{
		send: make(chan []byte, 1024),
		closeSlow: func() {
			conn.Close(websocket.StatusPolicyViolation, "connection too slow to keep up with messages")
		},
	}

	h.addSubscriber(s)
	defer h.deleteSubscriber(s)

	// send welcome message
	s.send <- []byte(`{"bufferSoc":0,"loadpoints.0.phasesConfigured":null,"savingsTotalCharged":12.804,"loadpoints.0.pvAction":"inactive","auth":{"vehicles":{}},"batteryCapacity":13,"smartCostUnit":"gCO2eq","vehicles":["blauer e-Golf","weißes Model 3","grüner Honda e","schwarzes VanMoof","Wärmepumpe"],"loadpoints.0.phasesActive":1,"loadpoints.0.phaseRemaining":0,"loadpoints.1.chargePower":0,"loadpoints.0.connectedDuration":0,"loadpoints.0.guardAction":"inactive","loadpoints.0.vehicleIcon":"","loadpoints.0.mode":"pv","loadpoints.1.phasesEnabled":0,"loadpoints.0.connected":true,"batteryConfigured":true,"residualPower":0,"loadpoints.0.maxCurrent":16,"sponsor":"sponsorship unavailable","loadpoints.0.phasesEnabled":1,"loadpoints.1.vehicleCapacity":80,"loadpoints.0.enabled":true,"loadpoints.1.phaseRemaining":0,"loadpoints.1.guardAction":"inactive","version":"0.0.1-alpha","sponsorTokenExpires":0,"loadpoints.0.minCurrent":6,"loadpoints.0.vehicleCapacity":44,"loadpoints.1.phasesActive":3,"loadpoints.1.phaseAction":"inactive","loadpoints.1.vehiclePresent":true,"loadpoints.1.vehicleIcon":"","loadpoints.1.mode":"off","savingsEffectivePrice":0.082125,"gridConfigured":true,"loadpoints.0.phaseAction":"inactive","loadpoints.0.vehicleTargetSoc":0,"loadpoints.1.minCurrent":6,"loadpoints.1.targetSoc":75,"loadpoints.1.targetEnergy":0,"loadpoints.0.charging":true,"prioritySoc":0,"loadpoints.0.chargerFeatureIntegratedDevice":false,"loadpoints.0.vehicleDetectionActive":false,"loadpoints.1.guardRemaining":0,"loadpoints.0.chargeCurrent":16,"batterySoc":55,"tariffEffectivePrice":0.08,"loadpoints.0.vehicleSoc":62.2,"pv":[{"power":8179.472084980387}],"loadpoints.0.chargePower":3680,"batteryPower":0,"siteTitle":"Zuhause","savingsSince":"2023-03-09T22:59:09+01:00","loadpoints.0.minSoc":0,"loadpoints.0.vehicleTitle":"blauer e-Golf","loadpoints.0.planActive":false,"gridPower":-4175.3,"homePower":324.22,"tariffCo2":675,"savingsSelfConsumptionCharged":12.626,"loadpoints.0.pvRemaining":0,"loadpoints.0.vehicleRange":182,"loadpoints.1.title":"Garage","loadpoints.1.pvAction":"inactive","loadpoints.1.phasesConfigured":0,"loadpoints.1.chargerFeatureIntegratedDevice":false,"loadpoints.1.chargerIcon":"","battery":[{"power":0,"soc":55,"capacity":13.4}],"loadpoints.0.guardRemaining":0,"loadpoints.0.targetEnergy":0,"loadpoints.0.vehiclePresent":true,"loadpoints.1.maxCurrent":16,"loadpoints.0.chargeRemainingDuration":13296,"loadpoints.0.chargeRemainingEnergy":13591,"greenShare":1,"savingsGridCharged":0.17814,"loadpoints.1.vehicleRange":0,"loadpoints.0.chargedEnergy":0.0014228,"tariffFeedIn":0.08,"tariffEffectiveCo2":0,"smartCostLimit":0,"currency":"EUR","loadpoints.1.minSoc":0,"loadpoints.1.vehicleTitle":"weißes Model 3","savingsSelfConsumptionPercent":98.609,"availableVersion":"0.116.7","loadpoints.0.chargerIcon":"","loadpoints.1.vehicleFeatureOffline":false,"pvPower":8179.5,"loadpoints.0.chargeDuration":0,"loadpoints.1.vehicleTargetSoc":0,"tariffGrid":0.399,"savingsAmount":4.0079,"pvConfigured":true,"loadpoints.0.title":"Carport","loadpoints.0.targetSoc":90,"loadpoints.1.pvRemaining":0,"smartCostAvailable":true,"loadpoints.0.vehicleFeatureOffline":false,"loadpoints.1.vehicleSoc":0,"loadpoints.1.vehicleDetectionActive":false}`)

	for {
		select {
		case msg := <-s.send:
			if err := writeTimeout(ctx, socketWriteTimeout, conn, msg); err != nil {
				return err
			}
		case <-ctx.Done():
			return ctx.Err()
		}
	}
}

The welcome message contains a bunch of JSON state that each client obtains on connection. This works with Chrome and Firefox, but not Safari. On Safari, the client apparently receives the data but then disconnects. Server log sometimes shows

failed to write msg: failed to write: failed to write data frame: WebSocket closed: received close frame: status = StatusProtocolError and reason = ""

The error does not happens when no welcome message is sent or the welcome message is small. I did not try yet to determine if the size of message has a clear bound for the error to occur.

Any idea what might be special about Safari in this context?

[andig]

Breaks at 512 characters. Duplicate of #218?

[nhooyr]

Yup I think so. Compression will be disabled by default in the next release anyway. Not very reliable based on the number of issues related to it.