Add support new version of Slack applocation

- Added support of Event API in socketMode
- Fix files upload for new applications

vendor/github.com/slack-go/slack/socketmode/client.go

@@ -0,0 +1,63 @@
+package socketmode
+
+import (
+	"encoding/json"
+	"time"
+
+	"github.com/slack-go/slack"
+
+	"github.com/gorilla/websocket"
+)
+
+type ConnectedEvent struct {
+	ConnectionCount int // 1 = first time, 2 = second time
+	Info            *slack.SocketModeConnection
+}
+
+type DebugInfo struct {
+	// Host is the name of the host name on the Slack end, that can be something like `applink-7fc4fdbb64-4x5xq`
+	Host string `json:"host"`
+
+	// `hello` type only
+	BuildNumber               int `json:"build_number"`
+	ApproximateConnectionTime int `json:"approximate_connection_time"`
+}
+
+type ConnectionInfo struct {
+	AppID string `json:"app_id"`
+}
+
+type SocketModeMessagePayload struct {
+	Event json.RawMessage `json:"event"`
+}
+
+// Client is a Socket Mode client that allows programs to use [Events API](https://api.slack.com/events-api)
+// and [interactive components](https://api.slack.com/interactivity) over WebSocket.
+// Please see [Intro to Socket Mode](https://api.slack.com/apis/connections/socket) for more information
+// on Socket Mode.
+//
+// The implementation is highly inspired by https://www.npmjs.com/package/@slack/socket-mode,
+// but the structure and the design has been adapted as much as possible to that of our RTM client for consistency
+// within the library.
+//
+// You can instantiate the socket mode client with
+// Client's New() and call Run() to start it. Please see examples/socketmode for the usage.
+type Client struct {
+	// Client is the main API, embedded
+	slack.Client
+
+	// maxPingInterval is the maximum duration elapsed after the last WebSocket PING sent from Slack
+	// until Client considers the WebSocket connection is dead and needs to be reopened.
+	maxPingInterval time.Duration
+
+	// Connection life-cycle
+	Events              chan Event
+	socketModeResponses chan *Response
+
+	// dialer is a gorilla/websocket Dialer. If nil, use the default
+	// Dialer.
+	dialer *websocket.Dialer
+
+	debug bool
+	log   ilogger
+}

vendor/github.com/slack-go/slack/socketmode/event.go

@@ -0,0 +1,30 @@
+package socketmode
+
+import "encoding/json"
+
+// Event is the event sent to the consumer of Client
+type Event struct {
+	Type EventType
+	Data interface{}
+
+	// Request is the json-decoded raw WebSocket message that is received via the Slack Socket Mode
+	// WebSocket connection.
+	Request *Request
+}
+
+type ErrorBadMessage struct {
+	Cause   error
+	Message json.RawMessage
+}
+
+type ErrorWriteFailed struct {
+	Cause    error
+	Response *Response
+}
+
+type errorRequestedDisconnect struct {
+}
+
+func (e errorRequestedDisconnect) Error() string {
+	return "disconnection requested: Slack requested us to disconnect"
+}

vendor/github.com/slack-go/slack/socketmode/log.go

@@ -0,0 +1,51 @@
+package socketmode
+
+import "fmt"
+
+// TODO merge logger, ilogger, and internalLogger with the top-level package's equivalents
+
+// logger is a logger interface compatible with both stdlib and some
+// 3rd party loggers.
+type logger interface {
+	Output(int, string) error
+}
+
+// ilogger represents the internal logging api we use.
+type ilogger interface {
+	logger
+	Print(...interface{})
+	Printf(string, ...interface{})
+	Println(...interface{})
+}
+
+// internalLog implements the additional methods used by our internal logging.
+type internalLog struct {
+	logger
+}
+
+// Println replicates the behaviour of the standard logger.
+func (t internalLog) Println(v ...interface{}) {
+	t.Output(2, fmt.Sprintln(v...))
+}
+
+// Printf replicates the behaviour of the standard logger.
+func (t internalLog) Printf(format string, v ...interface{}) {
+	t.Output(2, fmt.Sprintf(format, v...))
+}
+
+// Print replicates the behaviour of the standard logger.
+func (t internalLog) Print(v ...interface{}) {
+	t.Output(2, fmt.Sprint(v...))
+}
+
+func (smc *Client) Debugf(format string, v ...interface{}) {
+	if smc.debug {
+		smc.log.Output(2, fmt.Sprintf(format, v...))
+	}
+}
+
+func (smc *Client) Debugln(v ...interface{}) {
+	if smc.debug {
+		smc.log.Output(2, fmt.Sprintln(v...))
+	}
+}

vendor/github.com/slack-go/slack/socketmode/request.go

@@ -0,0 +1,38 @@
+package socketmode
+
+import "encoding/json"
+
+// Request maps to the content of each WebSocket message received via a Socket Mode WebSocket connection
+//
+// We call this a "request" rather than e.g. a WebSocket message or an Socket Mode "event" following python-slack-sdk:
+//
+// https://github.com/slackapi/python-slack-sdk/blob/3f1c4c6e27bf7ee8af57699b2543e6eb7848bcf9/slack_sdk/socket_mode/request.py#L6
+//
+// We know that node-slack-sdk calls it an "event", that makes it hard for us to distinguish our client's own event
+// that wraps both internal events and Socket Mode "events", vs node-slack-sdk's is for the latter only.
+//
+// https://github.com/slackapi/node-slack-sdk/blob/main/packages/socket-mode/src/SocketModeClient.ts#L537
+type Request struct {
+	Type string `json:"type"`
+
+	// `hello` type only
+	NumConnections int            `json:"num_connections"`
+	ConnectionInfo ConnectionInfo `json:"connection_info"`
+
+	// `disconnect` type only
+
+	// Reason can be "warning" or else
+	Reason string `json:"reason"`
+
+	// `hello` and `disconnect` types only
+	DebugInfo DebugInfo `json:"debug_info"`
+
+	// `events_api` type only
+	EnvelopeID string `json:"envelope_id"`
+	// TODO Can it really be a non-object type?
+	// See https://github.com/slackapi/python-slack-sdk/blob/3f1c4c6e27bf7ee8af57699b2543e6eb7848bcf9/slack_sdk/socket_mode/request.py#L26-L31
+	Payload                json.RawMessage `json:"payload"`
+	AcceptsResponsePayload bool            `json:"accepts_response_payload"`
+	RetryAttempt           int             `json:"retry_attempt"`
+	RetryReason            string          `json:"retry_reason"`
+}

vendor/github.com/slack-go/slack/socketmode/response.go

@@ -0,0 +1,6 @@
+package socketmode
+
+type Response struct {
+	EnvelopeID string      `json:"envelope_id"`
+	Payload    interface{} `json:"payload,omitempty"`
+}

vendor/github.com/slack-go/slack/socketmode/socket_mode_managed_conn.go

@@ -0,0 +1,633 @@
+package socketmode
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"sync"
+	"time"
+
+	"github.com/gorilla/websocket"
+
+	"github.com/slack-go/slack"
+	"github.com/slack-go/slack/internal/backoff"
+	"github.com/slack-go/slack/internal/timex"
+	"github.com/slack-go/slack/slackevents"
+)
+
+// Run is a blocking function that connects the Slack Socket Mode API and handles all incoming
+// requests and outgoing responses.
+//
+// The consumer of the Client and this function should read the Client.Events channel to receive
+// `socketmode.Event`s that includes the client-specific events that may or may not wrap Socket Mode requests.
+//
+// Note that this function automatically reconnect on requested by Slack through a `disconnect` message.
+// This function exists with an error only when a reconnection is failued due to some reason.
+// If you want to retry even on reconnection failure, you'd need to write your own wrapper for this function
+// to do so.
+func (smc *Client) Run() error {
+	return smc.RunContext(context.TODO())
+}
+
+// RunContext is a blocking function that connects the Slack Socket Mode API and handles all incoming
+// requests and outgoing responses.
+//
+// The consumer of the Client and this function should read the Client.Events channel to receive
+// `socketmode.Event`s that includes the client-specific events that may or may not wrap Socket Mode requests.
+//
+// Note that this function automatically reconnect on requested by Slack through a `disconnect` message.
+// This function exists with an error only when a reconnection is failued due to some reason.
+// If you want to retry even on reconnection failure, you'd need to write your own wrapper for this function
+// to do so.
+func (smc *Client) RunContext(ctx context.Context) error {
+	for connectionCount := 0; ; connectionCount++ {
+		if err := smc.run(ctx, connectionCount); err != nil {
+			return err
+		}
+
+		// Continue and run the loop again to reconnect
+	}
+}
+
+func (smc *Client) run(ctx context.Context, connectionCount int) error {
+	messages := make(chan json.RawMessage, 1)
+
+	pingChan := make(chan time.Time, 1)
+	pingHandler := func(_ string) error {
+		select {
+		case pingChan <- time.Now():
+		default:
+		}
+
+		return nil
+	}
+
+	// Start trying to connect
+	// the returned err is already passed onto the Events channel
+	//
+	// We also configures an additional ping handler for the deadmanTimer that triggers a timeout when
+	// Slack did not send us WebSocket PING for more than Client.maxPingInterval.
+	// We can use `<-smc.pingTimeout.C` to wait for the timeout.
+	info, conn, err := smc.connect(ctx, connectionCount, pingHandler)
+	if err != nil {
+		// when the connection is unsuccessful its fatal, and we need to bail out.
+		smc.Debugf("Failed to connect with Socket Mode on try %d: %s", connectionCount, err)
+
+		return err
+	}
+
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+
+	smc.sendEvent(ctx, newEvent(EventTypeConnected, &ConnectedEvent{
+		ConnectionCount: connectionCount,
+		Info:            info,
+	}))
+
+	smc.Debugf("WebSocket connection succeeded on try %d", connectionCount)
+
+	// We're now connected so we can set up listeners
+
+	wg := new(sync.WaitGroup)
+	// sendErr relies on the buffer of 1 here
+	errc := make(chan error, 1)
+	sendErr := func(err error) {
+		select {
+		case errc <- err:
+		default:
+		}
+	}
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		defer cancel()
+
+		// The response sender sends Socket Mode responses over the WebSocket conn
+		if err := smc.runResponseSender(ctx, conn); err != nil {
+			sendErr(err)
+		}
+	}()
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		defer cancel()
+
+		// The handler reads Socket Mode requests, and enqueues responses for sending by the response sender
+		if err := smc.runRequestHandler(ctx, messages); err != nil {
+			sendErr(err)
+		}
+	}()
+
+	go func() {
+		defer cancel()
+		// We close messages here as it is the producer for the channel.
+		defer close(messages)
+
+		// The receiver reads WebSocket messages, and enqueues parsed Socket Mode requests to be handled by
+		// the request handler
+		if err := smc.runMessageReceiver(ctx, conn, messages); err != nil {
+			sendErr(err)
+		}
+	}()
+
+	wg.Add(1)
+	go func(pingInterval time.Duration) {
+		defer wg.Done()
+		defer func() {
+			// Detect when the connection is dead and try close connection.
+			if err := conn.Close(); err != nil {
+				smc.Debugf("Failed to close connection: %v", err)
+			}
+		}()
+
+		done := ctx.Done()
+		var lastPing time.Time
+
+		// More efficient than constantly resetting a timer w/ Stop+Reset
+		ticker := time.NewTicker(pingInterval)
+		defer ticker.Stop()
+
+		for {
+			select {
+			case <-done:
+				return
+
+			case lastPing = <-pingChan:
+				// This case gets the time of the last ping.
+				// If this case never fires then the pingHandler was never called
+				// in which case lastPing is the zero time.Time value, and will 'fail'
+				// the next tick, causing us to exit.
+
+			case now := <-ticker.C:
+				// Our last ping is older than our interval
+				if now.Sub(lastPing) > pingInterval {
+					sendErr(errors.New("ping timeout: Slack did not send us WebSocket PING for more than Client.maxInterval"))
+
+					cancel()
+					return
+				}
+			}
+		}
+	}(smc.maxPingInterval)
+
+	wg.Wait()
+
+	select {
+	case err = <-errc:
+		// Get buffered error
+	default:
+		// Or nothing if they all exited nil
+	}
+
+	if errors.Is(err, context.Canceled) {
+		return err
+	}
+
+	// wg.Wait() finishes only after any of the above go routines finishes and cancels the
+	// context, allowing the other threads to shut down gracefully.
+	// Also, we can expect our (first)err to be not nil, as goroutines can finish only on error.
+	smc.Debugf("Reconnecting due to %v", err)
+
+	return nil
+}
+
+// connect attempts to connect to the slack websocket API. It handles any
+// errors that occur while connecting and will return once a connection
+// has been successfully opened.
+func (smc *Client) connect(ctx context.Context, connectionCount int, additionalPingHandler func(string) error) (*slack.SocketModeConnection, *websocket.Conn, error) {
+	const (
+		errInvalidAuth      = "invalid_auth"
+		errInactiveAccount  = "account_inactive"
+		errMissingAuthToken = "not_authed"
+		errTokenRevoked     = "token_revoked"
+	)
+
+	// used to provide exponential backoff wait time with jitter before trying
+	// to connect to slack again
+	boff := &backoff.Backoff{
+		Max: 5 * time.Minute,
+	}
+
+	for {
+		var (
+			backoff time.Duration
+		)
+
+		// send connecting event
+		smc.sendEvent(ctx, newEvent(EventTypeConnecting, &slack.ConnectingEvent{
+			Attempt:         boff.Attempts() + 1,
+			ConnectionCount: connectionCount,
+		}))
+
+		// attempt to start the connection
+		info, conn, err := smc.openAndDial(ctx, additionalPingHandler)
+		if err == nil {
+			return info, conn, nil
+		}
+
+		// check for fatal errors
+		switch err.Error() {
+		case errInvalidAuth, errInactiveAccount, errMissingAuthToken, errTokenRevoked:
+			smc.Debugf("invalid auth when connecting with SocketMode: %s", err)
+			return nil, nil, err
+		default:
+		}
+
+		var (
+			actual  slack.StatusCodeError
+			rlError *slack.RateLimitedError
+		)
+
+		if errors.As(err, &actual) && actual.Code == http.StatusNotFound {
+			smc.Debugf("invalid auth when connecting with Socket Mode: %s", err)
+			smc.sendEvent(ctx, newEvent(EventTypeInvalidAuth, &slack.InvalidAuthEvent{}))
+
+			return nil, nil, err
+		} else if errors.As(err, &rlError) {
+			backoff = rlError.RetryAfter
+		}
+
+		// If we check for errors.Is(err, context.Canceled) here and
+		// return early then we don't send the Event below that some users
+		// may already rely on; ie a behavior change.
+
+		backoff = timex.Max(backoff, boff.Duration())
+		// any other errors are treated as recoverable and we try again after
+		// sending the event along the Events channel
+		smc.sendEvent(ctx, newEvent(EventTypeConnectionError, &slack.ConnectionErrorEvent{
+			Attempt:  boff.Attempts(),
+			Backoff:  backoff,
+			ErrorObj: err,
+		}))
+
+		// get time we should wait before attempting to connect again
+		smc.Debugf("reconnection %d failed: %s reconnecting in %v\n", boff.Attempts(), err, backoff)
+
+		// wait for one of the following to occur,
+		// backoff duration has elapsed, disconnectCh is signalled, or
+		// the smc finishes disconnecting.
+		timer := time.NewTimer(backoff)
+		select {
+		case <-timer.C: // retry after the backoff.
+		case <-ctx.Done():
+			timer.Stop()
+			return nil, nil, ctx.Err()
+		}
+	}
+}
+
+// openAndDial attempts to open a Socket Mode connection and dial to the connection endpoint using WebSocket.
+// It returns the  full information returned by the "apps.connections.open" method on the
+// Slack API.
+func (smc *Client) openAndDial(ctx context.Context, additionalPingHandler func(string) error) (info *slack.SocketModeConnection, _ *websocket.Conn, err error) {
+	var (
+		url string
+	)
+
+	smc.Debugf("Starting SocketMode")
+	info, url, err = smc.OpenContext(ctx)
+
+	if err != nil {
+		smc.Debugf("Failed to start or connect with SocketMode: %s", err)
+		return nil, nil, err
+	}
+
+	smc.Debugf("Dialing to websocket on url %s", url)
+	// Only use HTTPS for connections to prevent MITM attacks on the connection.
+	upgradeHeader := http.Header{}
+	upgradeHeader.Add("Origin", "https://api.slack.com")
+	dialer := websocket.DefaultDialer
+	if smc.dialer != nil {
+		dialer = smc.dialer
+	}
+	conn, _, err := dialer.DialContext(ctx, url, upgradeHeader)
+	if err != nil {
+		smc.Debugf("Failed to dial to the websocket: %s", err)
+		return nil, nil, err
+	}
+	if additionalPingHandler == nil {
+		additionalPingHandler = func(_ string) error { return nil }
+	}
+
+	conn.SetPingHandler(func(appData string) error {
+		if err := additionalPingHandler(appData); err != nil {
+			return err
+		}
+
+		smc.handlePing(conn, appData)
+
+		return nil
+	})
+
+	// We don't need to conn.SetCloseHandler because the default handler is effective enough that
+	// it sends back the CLOSE message to the server and let conn.ReadJSON() fail with CloseError.
+	// The CloseError must be handled normally in our receiveMessagesInto function.
+	//conn.SetCloseHandler(func(code int, text string) error {
+	//  ...
+	// })
+
+	return info, conn, err
+}
+
+// runResponseSender runs the handler that reads Socket Mode responses enqueued onto Client.socketModeResponses channel
+// and sends them one by one over the WebSocket connection.
+// Gorilla WebSocket is not goroutine safe hence this needs to be the single place you write to the WebSocket connection.
+func (smc *Client) runResponseSender(ctx context.Context, conn *websocket.Conn) error {
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		// 3. listen for messages that need to be sent
+		case res := <-smc.socketModeResponses:
+			smc.Debugf("Sending Socket Mode response with envelope ID %q: %v", res.EnvelopeID, res)
+
+			if err := unsafeWriteSocketModeResponse(conn, res); err != nil {
+				smc.sendEvent(ctx, newEvent(EventTypeErrorWriteFailed, &ErrorWriteFailed{
+					Cause:    err,
+					Response: res,
+				}))
+			}
+
+			smc.Debugf("Finished sending Socket Mode response with envelope ID %q", res.EnvelopeID)
+		}
+	}
+}
+
+// runRequestHandler is a blocking function that runs the Socket Mode request receiver.
+//
+// It reads WebSocket messages sent from Slack's Socket Mode WebSocket connection,
+// parses them as Socket Mode requests, and processes them and optionally emit our own events into Client.Events channel.
+func (smc *Client) runRequestHandler(ctx context.Context, websocket chan json.RawMessage) error {
+	for {
+		select {
+		case <-ctx.Done():
+			return ctx.Err()
+		case message, ok := <-websocket:
+			if !ok {
+				// The producer closed the channel because it encountered an error (or panic),
+				// we need only return.
+				return nil
+			}
+
+			smc.Debugf("Received WebSocket message: %s", message)
+
+			// listen for incoming messages that need to be parsed
+			evt, err := smc.parseEvent(message)
+			if err != nil {
+				smc.sendEvent(ctx, newEvent(EventTypeErrorBadMessage, &ErrorBadMessage{
+					Cause:   err,
+					Message: message,
+				}))
+			} else if evt != nil {
+				if evt.Type == EventTypeDisconnect {
+					// We treat the `disconnect` request from Slack as an error internally,
+					// so that we can tell the consumer of this function to reopen the connection on it.
+					return errorRequestedDisconnect{}
+				}
+
+				smc.sendEvent(ctx, *evt)
+			}
+		}
+	}
+}
+
+// runMessageReceiver monitors the Socket Mode opened WebSocket connection for any incoming
+// messages. It pushes the raw events into the channel.
+// The receiver runs until the context is closed.
+func (smc *Client) runMessageReceiver(ctx context.Context, conn *websocket.Conn, sink chan json.RawMessage) error {
+	for {
+		if err := smc.receiveMessagesInto(ctx, conn, sink); err != nil {
+			return err
+		}
+	}
+}
+
+// unsafeWriteSocketModeResponse sends a WebSocket message back to Slack.
+// WARNING: Call to this function must be serialized!
+//
+// Here's why - Gorilla WebSocket's Writes functions are not concurrency-safe.
+// That is, we must serialize all the writes to it with e.g. a goroutine or mutex.
+// We intentionally chose to use goroutine, which makes it harder to propagate write errors to the caller,
+// but is more computationally efficient.
+//
+// See the below for more information on this topic:
+// https://stackoverflow.com/questions/43225340/how-to-ensure-concurrency-in-golang-gorilla-websocket-package
+func unsafeWriteSocketModeResponse(conn *websocket.Conn, res *Response) error {
+	// set a write deadline on the connection
+	if err := conn.SetWriteDeadline(time.Now().Add(10 * time.Second)); err != nil {
+		return err
+	}
+
+	// Remove write deadline regardless of WriteJSON succeeds or not
+	defer conn.SetWriteDeadline(time.Time{})
+
+	return conn.WriteJSON(res)
+}
+
+func newEvent(tpe EventType, data interface{}, req ...*Request) Event {
+	evt := Event{Type: tpe, Data: data}
+
+	if len(req) > 0 {
+		evt.Request = req[0]
+	}
+
+	return evt
+}
+
+// Ack acknowledges the Socket Mode request with the payload.
+//
+// This tells Slack that the we have received the request denoted by the envelope ID,
+// by sending back the envelope ID over the WebSocket connection.
+func (smc *Client) Ack(req Request, payload ...interface{}) {
+	var pld interface{}
+	if len(payload) > 0 {
+		pld = payload[0]
+	}
+
+	smc.AckCtx(context.TODO(), req.EnvelopeID, pld)
+}
+
+// AckCtx acknowledges the Socket Mode request envelope ID with the payload.
+//
+// This tells Slack that the we have received the request denoted by the request (envelope) ID,
+// by sending back the ID over the WebSocket connection.
+func (smc *Client) AckCtx(ctx context.Context, reqID string, payload interface{}) error {
+	return smc.SendCtx(ctx, Response{
+		EnvelopeID: reqID,
+		Payload:    payload,
+	})
+}
+
+// Send sends the Socket Mode response over a WebSocket connection.
+// This is usually used for acknowledging requests, but if you need more control over Client.Ack().
+// It's normally recommended to use Client.Ack() instead of this.
+func (smc *Client) Send(res Response) {
+	smc.SendCtx(context.TODO(), res)
+}
+
+// SendCtx sends the Socket Mode response over a WebSocket connection.
+// This is usually used for acknowledging requests, but if you need more control
+// it's normally recommended to use Client.AckCtx() instead of this.
+func (smc *Client) SendCtx(ctx context.Context, res Response) error {
+	if smc.debug {
+		js, err := json.Marshal(res)
+
+		// Log the error so users of `Send` don't see it entirely disappear as that method
+		// does not return an error and used to panic on failure (with or without debug)
+		smc.Debugf("Scheduling Socket Mode response (error: %v) for envelope ID %s: %s", err, res.EnvelopeID, js)
+		if err != nil {
+			return err
+		}
+	}
+
+	select {
+	case <-ctx.Done():
+		return ctx.Err()
+	case smc.socketModeResponses <- &res:
+	}
+
+	return nil
+}
+
+// receiveMessagesInto attempts to receive an event from the WebSocket connection for Socket Mode.
+// This will block until a frame is available from the WebSocket.
+// If the read from the WebSocket results in a fatal error, this function will return non-nil.
+func (smc *Client) receiveMessagesInto(ctx context.Context, conn *websocket.Conn, sink chan json.RawMessage) error {
+	smc.Debugf("Starting to receive message")
+	defer smc.Debugf("Finished to receive message")
+
+	event := json.RawMessage{}
+	err := conn.ReadJSON(&event)
+	if err != nil {
+		// check if the connection was closed.
+		// This version of the gorilla/websocket package also does a type assertion
+		// on the error, rather than unwrapping it, so we'll do the unwrapping then pass
+		// the unwrapped error
+		var wsErr *websocket.CloseError
+		if errors.As(err, &wsErr) && websocket.IsUnexpectedCloseError(wsErr) {
+			return err
+		}
+
+		if errors.Is(err, io.ErrUnexpectedEOF) {
+			// EOF's don't seem to signify a failed connection so instead we ignore
+			// them here and detect a failed connection upon attempting to send a
+			// 'PING' message
+
+			// Unlike RTM, we don't ping from the our end as there seem to have no client ping.
+			// We just continue to the next loop so that we `smc.disconnected` should be received if
+			// this EOF error was actually due to disconnection.
+
+			return nil
+		}
+
+		// All other errors from ReadJSON come from NextReader, and should
+		// kill the read loop and force a reconnect.
+		// TODO: Unless it's a JSON unmarshal-type error in which case maybe reconnecting isn't needed...
+		smc.sendEvent(ctx, newEvent(EventTypeIncomingError, &slack.IncomingEventError{
+			ErrorObj: err,
+		}))
+
+		return err
+	}
+
+	if smc.debug {
+		buf := &bytes.Buffer{}
+		d := json.NewEncoder(buf)
+		d.SetIndent("", "  ")
+		if err := d.Encode(event); err != nil {
+			smc.Debugln("Failed encoding decoded json:", err)
+		}
+		reencoded := buf.String()
+
+		smc.Debugln("Incoming WebSocket message:", reencoded)
+	}
+
+	select {
+	case sink <- event:
+	case <-ctx.Done():
+		smc.Debugln("cancelled while attempting to send raw event")
+
+		return ctx.Err()
+	}
+
+	return nil
+}
+
+// parseEvent takes a raw JSON message received from the slack websocket
+// and handles the encoded event.
+// returns the our own event that wraps the socket mode request.
+func (smc *Client) parseEvent(wsMsg json.RawMessage) (*Event, error) {
+	req := &Request{}
+	err := json.Unmarshal(wsMsg, req)
+	if err != nil {
+		return nil, fmt.Errorf("unmarshalling WebSocket message: %w", err)
+	}
+
+	var evt Event
+
+	// See below two links for all the available message types.
+	// - https://github.com/slackapi/node-slack-sdk/blob/c3f4d7109062a0356fb765d53794b7b5f6b3b5ae/packages/socket-mode/src/SocketModeClient.ts#L533
+	// - https://api.slack.com/apis/connections/socket-implement
+	switch req.Type {
+	case RequestTypeHello:
+		evt = newEvent(EventTypeHello, nil, req)
+	case RequestTypeEventsAPI:
+		payloadEvent := req.Payload
+
+		eventsAPIEvent, err := slackevents.ParseEvent(payloadEvent, slackevents.OptionNoVerifyToken())
+		if err != nil {
+			return nil, fmt.Errorf("parsing Events API event: %w", err)
+		}
+
+		evt = newEvent(EventTypeEventsAPI, eventsAPIEvent, req)
+	case RequestTypeDisconnect:
+		// See https://api.slack.com/apis/connections/socket-implement#disconnect
+
+		evt = newEvent(EventTypeDisconnect, nil, req)
+	case RequestTypeSlashCommands:
+		// See https://api.slack.com/apis/connections/socket-implement#command
+		var cmd slack.SlashCommand
+
+		if err := json.Unmarshal(req.Payload, &cmd); err != nil {
+			return nil, fmt.Errorf("parsing slash command: %w", err)
+		}
+
+		evt = newEvent(EventTypeSlashCommand, cmd, req)
+	case RequestTypeInteractive:
+		// See belows:
+		// - https://api.slack.com/apis/connections/socket-implement#button
+		// - https://api.slack.com/apis/connections/socket-implement#home
+		// - https://api.slack.com/apis/connections/socket-implement#modal
+		// - https://api.slack.com/apis/connections/socket-implement#menu
+
+		var callback slack.InteractionCallback
+
+		if err := json.Unmarshal(req.Payload, &callback); err != nil {
+			return nil, fmt.Errorf("parsing interaction callback: %w", err)
+		}
+
+		evt = newEvent(EventTypeInteractive, callback, req)
+	default:
+		return nil, fmt.Errorf("processing WebSocket message: encountered unsupported type %q", req.Type)
+	}
+
+	return &evt, nil
+}
+
+// handlePing handles an incoming 'PONG' message which should be in response to
+// a previously sent 'PING' message. This is then used to compute the
+// connection's latency.
+func (smc *Client) handlePing(conn *websocket.Conn, event string) {
+	smc.Debugf("WebSocket ping message received: %s", event)
+
+	// In WebSocket, we need to respond a PING from the server with a PONG with the same payload as the PING.
+	if err := conn.WriteControl(websocket.PongMessage, []byte(event), time.Now().Add(10*time.Second)); err != nil {
+		smc.Debugf("Failed writing WebSocket PONG message: %v", err)
+	}
+}

vendor/github.com/slack-go/slack/socketmode/socketmode.go

@@ -0,0 +1,133 @@
+package socketmode
+
+import (
+	"context"
+	"log"
+	"os"
+	"time"
+
+	"github.com/gorilla/websocket"
+
+	"github.com/slack-go/slack"
+)
+
+// EventType is the type of events that are emitted by scoketmode.Client.
+// You receive and handle those events from a socketmode.Client.Events channel.
+// Those event types does not necessarily match 1:1 to those of Slack Events API events.
+type EventType string
+
+const (
+	// The following request types are the types of requests sent from Slack via Socket Mode WebSocket connection
+	// and handled internally by the socketmode.Client.
+	// The consumer of socketmode.Client will never see it.
+
+	RequestTypeHello         = "hello"
+	RequestTypeEventsAPI     = "events_api"
+	RequestTypeDisconnect    = "disconnect"
+	RequestTypeSlashCommands = "slash_commands"
+	RequestTypeInteractive   = "interactive"
+
+	// The following event types are for events emitted by socketmode.Client itself and
+	// does not originate from Slack.
+	EventTypeConnecting       = EventType("connecting")
+	EventTypeInvalidAuth      = EventType("invalid_auth")
+	EventTypeConnectionError  = EventType("connection_error")
+	EventTypeConnected        = EventType("connected")
+	EventTypeIncomingError    = EventType("incoming_error")
+	EventTypeErrorWriteFailed = EventType("write_error")
+	EventTypeErrorBadMessage  = EventType("error_bad_message")
+
+	//
+	// The following event types are guaranteed to not change unless Slack changes
+	//
+
+	EventTypeHello        = EventType("hello")
+	EventTypeDisconnect   = EventType("disconnect")
+	EventTypeEventsAPI    = EventType("events_api")
+	EventTypeInteractive  = EventType("interactive")
+	EventTypeSlashCommand = EventType("slash_commands")
+
+	websocketDefaultTimeout = 10 * time.Second
+	defaultMaxPingInterval  = 30 * time.Second
+)
+
+// Open calls the "apps.connections.open" endpoint and returns the provided URL and the full Info block.
+//
+// To have a fully managed Websocket connection, use `New`, and call `Run()` on it.
+func (smc *Client) Open() (info *slack.SocketModeConnection, websocketURL string, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), websocketDefaultTimeout)
+	defer cancel()
+
+	return smc.StartSocketModeContext(ctx)
+}
+
+// OpenContext calls the "apps.connections.open" endpoint and returns the provided URL and the full Info block.
+//
+// To have a fully managed Websocket connection, use `New`, and call `Run()` on it.
+func (smc *Client) OpenContext(ctx context.Context) (info *slack.SocketModeConnection, websocketURL string, err error) {
+	return smc.StartSocketModeContext(ctx)
+}
+
+// Option options for the managed Client.
+type Option func(client *Client)
+
+// OptionDialer takes a gorilla websocket Dialer and uses it as the
+// Dialer when opening the websocket for the Socket Mode connection.
+func OptionDialer(d *websocket.Dialer) Option {
+	return func(smc *Client) {
+		smc.dialer = d
+	}
+}
+
+// OptionPingInterval determines how often we expect Slack to deliver WebSocket ping to us.
+// If no ping is delivered to us within this interval after the last ping, we assumes the WebSocket connection
+// is dead and needs to be reconnected.
+func OptionPingInterval(d time.Duration) Option {
+	return func(smc *Client) {
+		smc.maxPingInterval = d
+	}
+}
+
+// OptionDebug enable debugging for the client
+func OptionDebug(b bool) func(*Client) {
+	return func(c *Client) {
+		c.debug = b
+	}
+}
+
+// OptionLog set logging for client.
+func OptionLog(l logger) func(*Client) {
+	return func(c *Client) {
+		c.log = internalLog{logger: l}
+	}
+}
+
+// New returns a Socket Mode client which provides a fully managed connection to
+// Slack's Websocket-based Socket Mode.
+func New(api *slack.Client, options ...Option) *Client {
+	result := &Client{
+		Client:              *api,
+		Events:              make(chan Event, 50),
+		socketModeResponses: make(chan *Response, 20),
+		maxPingInterval:     defaultMaxPingInterval,
+		log:                 log.New(os.Stderr, "slack-go/slack/socketmode", log.LstdFlags|log.Lshortfile),
+	}
+
+	for _, opt := range options {
+		opt(result)
+	}
+
+	return result
+}
+
+// sendEvent safely sends an event into the Clients Events channel
+// and blocks until buffer space is had, or the context is canceled.
+// This prevents deadlocking in the event that Events buffer is full,
+// other goroutines are waiting, and/or timing allows receivers to exit
+// before all senders are finished.
+func (smc *Client) sendEvent(ctx context.Context, event Event) {
+	select {
+	case smc.Events <- event:
+	case <-ctx.Done():
+	}
+}

vendor/github.com/slack-go/slack/socketmode/socketmode_handler.go

@@ -0,0 +1,260 @@
+package socketmode
+
+import (
+	"context"
+	"github.com/slack-go/slack"
+	"github.com/slack-go/slack/slackevents"
+)
+
+type SocketmodeHandler struct {
+	Client *Client
+
+	//lvl 1 - the most generic type of event
+	EventMap map[EventType][]SocketmodeHandlerFunc
+	//lvl 2 - Manage event by inner type
+	InteractionEventMap map[slack.InteractionType][]SocketmodeHandlerFunc
+	EventApiMap         map[slackevents.EventsAPIType][]SocketmodeHandlerFunc
+	//lvl 3 - the most userfriendly way of managing event
+	InteractionBlockActionEventMap map[string]SocketmodeHandlerFunc
+	SlashCommandMap                map[string]SocketmodeHandlerFunc
+
+	Default SocketmodeHandlerFunc
+}
+
+// Handler have access to the event and socketmode client
+type SocketmodeHandlerFunc func(*Event, *Client)
+
+// Middleware accept SocketmodeHandlerFunc, and return SocketmodeHandlerFunc
+type SocketmodeMiddlewareFunc func(SocketmodeHandlerFunc) SocketmodeHandlerFunc
+
+// Initialization constructor for SocketmodeHandler
+func NewSocketmodeHandler(client *Client) *SocketmodeHandler {
+	eventMap := make(map[EventType][]SocketmodeHandlerFunc)
+	interactionEventMap := make(map[slack.InteractionType][]SocketmodeHandlerFunc)
+	eventApiMap := make(map[slackevents.EventsAPIType][]SocketmodeHandlerFunc)
+
+	interactionBlockActionEventMap := make(map[string]SocketmodeHandlerFunc)
+	slackCommandMap := make(map[string]SocketmodeHandlerFunc)
+
+	return &SocketmodeHandler{
+		Client:                         client,
+		EventMap:                       eventMap,
+		EventApiMap:                    eventApiMap,
+		InteractionEventMap:            interactionEventMap,
+		InteractionBlockActionEventMap: interactionBlockActionEventMap,
+		SlashCommandMap:                slackCommandMap,
+		Default: func(e *Event, c *Client) {
+			c.log.Printf("Unexpected event type received: %v\n", e.Type)
+		},
+	}
+}
+
+// Register a middleware or handler for an Event from socketmode
+// This most general entrypoint
+func (r *SocketmodeHandler) Handle(et EventType, f SocketmodeHandlerFunc) {
+	r.EventMap[et] = append(r.EventMap[et], f)
+}
+
+// Register a middleware or handler for an Interaction
+// There is several types of interactions, decated functions lets you better handle them
+// See
+// * HandleInteractionBlockAction
+// * (Not Implemented) HandleShortcut
+// * (Not Implemented) HandleView
+func (r *SocketmodeHandler) HandleInteraction(et slack.InteractionType, f SocketmodeHandlerFunc) {
+	r.InteractionEventMap[et] = append(r.InteractionEventMap[et], f)
+}
+
+// Register a middleware or handler for a Block Action referenced by its ActionID
+func (r *SocketmodeHandler) HandleInteractionBlockAction(actionID string, f SocketmodeHandlerFunc) {
+	if actionID == "" {
+		panic("invalid command cannot be empty")
+	}
+	if f == nil {
+		panic("invalid handler cannot be nil")
+	}
+	if _, exist := r.InteractionBlockActionEventMap[actionID]; exist {
+		panic("multiple registrations for actionID" + actionID)
+	}
+	r.InteractionBlockActionEventMap[actionID] = f
+}
+
+// Register a middleware or handler for an Event (from slackevents)
+func (r *SocketmodeHandler) HandleEvents(et slackevents.EventsAPIType, f SocketmodeHandlerFunc) {
+	r.EventApiMap[et] = append(r.EventApiMap[et], f)
+}
+
+// Register a middleware or handler for a Slash Command
+func (r *SocketmodeHandler) HandleSlashCommand(command string, f SocketmodeHandlerFunc) {
+	if command == "" {
+		panic("invalid command cannot be empty")
+	}
+	if f == nil {
+		panic("invalid handler cannot be nil")
+	}
+	if _, exist := r.SlashCommandMap[command]; exist {
+		panic("multiple registrations for command" + command)
+	}
+	r.SlashCommandMap[command] = f
+}
+
+// Register a middleware or handler to use as a last resort
+func (r *SocketmodeHandler) HandleDefault(f SocketmodeHandlerFunc) {
+	r.Default = f
+}
+
+// RunSlackEventLoop receives the event via the socket
+func (r *SocketmodeHandler) RunEventLoop() error {
+
+	go r.runEventLoop(context.Background())
+
+	return r.Client.Run()
+}
+
+func (r *SocketmodeHandler) RunEventLoopContext(ctx context.Context) error {
+	go r.runEventLoop(ctx)
+
+	return r.Client.RunContext(ctx)
+}
+
+// Call the dispatcher for each incomming event
+func (r *SocketmodeHandler) runEventLoop(ctx context.Context) {
+	for {
+		select {
+		case evt, ok := <-r.Client.Events:
+			if !ok {
+				return
+			}
+
+			r.dispatcher(evt)
+
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
+// Dispatch events to the specialized dispatcher
+func (r *SocketmodeHandler) dispatcher(evt Event) {
+	var ishandled bool
+
+	// Some eventType can be further decomposed
+	switch evt.Type {
+	case EventTypeInteractive:
+		ishandled = r.interactionDispatcher(&evt)
+	case EventTypeEventsAPI:
+		ishandled = r.eventAPIDispatcher(&evt)
+	case EventTypeSlashCommand:
+		ishandled = r.slashCommandDispatcher(&evt)
+	default:
+		ishandled = r.socketmodeDispatcher(&evt)
+	}
+
+	if !ishandled {
+		go r.Default(&evt, r.Client)
+	}
+}
+
+// Dispatch socketmode events to the registered middleware
+func (r *SocketmodeHandler) socketmodeDispatcher(evt *Event) bool {
+	if handlers, ok := r.EventMap[evt.Type]; ok {
+		// If we registered an event
+		for _, f := range handlers {
+			go f(evt, r.Client)
+		}
+
+		return true
+	}
+
+	return false
+}
+
+// Dispatch interactions to the registered middleware
+func (r *SocketmodeHandler) interactionDispatcher(evt *Event) bool {
+	var ishandled bool = false
+
+	interaction, ok := evt.Data.(slack.InteractionCallback)
+	if !ok {
+		r.Client.log.Printf("Ignored %+v\n", evt)
+		return false
+	}
+
+	// Level 1 - socketmode EventType
+	ishandled = r.socketmodeDispatcher(evt)
+
+	// Level 2 - interaction EventType
+	if handlers, ok := r.InteractionEventMap[interaction.Type]; ok {
+		// If we registered an event
+		for _, f := range handlers {
+			go f(evt, r.Client)
+		}
+
+		ishandled = true
+	}
+
+	// Level 3 - interaction with actionID
+	blockActions := interaction.ActionCallback.BlockActions
+	// outmoded approach won`t be implemented
+	// attachments_actions := interaction.ActionCallback.AttachmentActions
+
+	for _, action := range blockActions {
+		if handler, ok := r.InteractionBlockActionEventMap[action.ActionID]; ok {
+
+			go handler(evt, r.Client)
+
+			ishandled = true
+		}
+	}
+	return ishandled
+}
+
+// Dispatch eventAPI events to the registered middleware
+func (r *SocketmodeHandler) eventAPIDispatcher(evt *Event) bool {
+	var ishandled bool = false
+	eventsAPIEvent, ok := evt.Data.(slackevents.EventsAPIEvent)
+	if !ok {
+		r.Client.log.Printf("Ignored %+v\n", evt)
+		return false
+	}
+
+	innerEventType := slackevents.EventsAPIType(eventsAPIEvent.InnerEvent.Type)
+
+	// Level 1 - socketmode EventType
+	ishandled = r.socketmodeDispatcher(evt)
+
+	// Level 2 - EventAPI EventType
+	if handlers, ok := r.EventApiMap[innerEventType]; ok {
+		// If we registered an event
+		for _, f := range handlers {
+			go f(evt, r.Client)
+		}
+
+		ishandled = true
+	}
+
+	return ishandled
+}
+
+// Dispatch SlashCommands events to the registered middleware
+func (r *SocketmodeHandler) slashCommandDispatcher(evt *Event) bool {
+	var ishandled bool = false
+	slashCommandEvent, ok := evt.Data.(slack.SlashCommand)
+	if !ok {
+		r.Client.log.Printf("Ignored %+v\n", evt)
+		return false
+	}
+
+	// Level 1 - socketmode EventType
+	ishandled = r.socketmodeDispatcher(evt)
+
+	// Level 2 - SlackCommand by name
+	if handler, ok := r.SlashCommandMap[slashCommandEvent.Command]; ok {
+
+		go handler(evt, r.Client)
+
+		ishandled = true
+	}
+
+	return ishandled
+
+}