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https://github.com/42wim/matterbridge.git
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322 lines
11 KiB
Go
322 lines
11 KiB
Go
// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
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// See LICENSE.txt for license information.
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package model
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import (
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"bytes"
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"encoding/json"
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"net/http"
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"sync/atomic"
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"time"
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"github.com/gorilla/websocket"
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)
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const (
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SOCKET_MAX_MESSAGE_SIZE_KB = 8 * 1024 // 8KB
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PING_TIMEOUT_BUFFER_SECONDS = 5
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)
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type msgType int
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const (
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msgTypeJSON msgType = iota + 1
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msgTypePong
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)
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type writeMessage struct {
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msgType msgType
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data interface{}
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}
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const avgReadMsgSizeBytes = 1024
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// WebSocketClient stores the necessary information required to
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// communicate with a WebSocket endpoint.
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// A client must read from PingTimeoutChannel, EventChannel and ResponseChannel to prevent
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// deadlocks from occuring in the program.
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type WebSocketClient struct {
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Url string // The location of the server like "ws://localhost:8065"
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ApiUrl string // The API location of the server like "ws://localhost:8065/api/v3"
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ConnectUrl string // The WebSocket URL to connect to like "ws://localhost:8065/api/v3/path/to/websocket"
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Conn *websocket.Conn // The WebSocket connection
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AuthToken string // The token used to open the WebSocket connection
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Sequence int64 // The ever-incrementing sequence attached to each WebSocket action
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PingTimeoutChannel chan bool // The channel used to signal ping timeouts
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EventChannel chan *WebSocketEvent // The channel used to receive various events pushed from the server. For example: typing, posted
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ResponseChannel chan *WebSocketResponse // The channel used to receive responses for requests made to the server
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ListenError *AppError // A field that is set if there was an abnormal closure of the WebSocket connection
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writeChan chan writeMessage
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pingTimeoutTimer *time.Timer
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quitPingWatchdog chan struct{}
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quitWriterChan chan struct{}
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resetTimerChan chan struct{}
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closed int32
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}
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// NewWebSocketClient constructs a new WebSocket client with convenience
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// methods for talking to the server.
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func NewWebSocketClient(url, authToken string) (*WebSocketClient, *AppError) {
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return NewWebSocketClientWithDialer(websocket.DefaultDialer, url, authToken)
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}
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// NewWebSocketClientWithDialer constructs a new WebSocket client with convenience
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// methods for talking to the server using a custom dialer.
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func NewWebSocketClientWithDialer(dialer *websocket.Dialer, url, authToken string) (*WebSocketClient, *AppError) {
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conn, _, err := dialer.Dial(url+API_URL_SUFFIX+"/websocket", nil)
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if err != nil {
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return nil, NewAppError("NewWebSocketClient", "model.websocket_client.connect_fail.app_error", nil, err.Error(), http.StatusInternalServerError)
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}
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client := &WebSocketClient{
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Url: url,
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ApiUrl: url + API_URL_SUFFIX,
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ConnectUrl: url + API_URL_SUFFIX + "/websocket",
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Conn: conn,
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AuthToken: authToken,
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Sequence: 1,
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PingTimeoutChannel: make(chan bool, 1),
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EventChannel: make(chan *WebSocketEvent, 100),
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ResponseChannel: make(chan *WebSocketResponse, 100),
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writeChan: make(chan writeMessage),
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quitPingWatchdog: make(chan struct{}),
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quitWriterChan: make(chan struct{}),
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resetTimerChan: make(chan struct{}),
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}
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client.configurePingHandling()
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go client.writer()
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client.SendMessage(WEBSOCKET_AUTHENTICATION_CHALLENGE, map[string]interface{}{"token": authToken})
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return client, nil
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}
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// NewWebSocketClient4 constructs a new WebSocket client with convenience
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// methods for talking to the server. Uses the v4 endpoint.
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func NewWebSocketClient4(url, authToken string) (*WebSocketClient, *AppError) {
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return NewWebSocketClient4WithDialer(websocket.DefaultDialer, url, authToken)
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}
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// NewWebSocketClient4WithDialer constructs a new WebSocket client with convenience
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// methods for talking to the server using a custom dialer. Uses the v4 endpoint.
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func NewWebSocketClient4WithDialer(dialer *websocket.Dialer, url, authToken string) (*WebSocketClient, *AppError) {
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return NewWebSocketClientWithDialer(dialer, url, authToken)
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}
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// Connect creates a websocket connection with the given ConnectUrl.
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// This is racy and error-prone should not be used. Use any of the New* functions to create a websocket.
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func (wsc *WebSocketClient) Connect() *AppError {
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return wsc.ConnectWithDialer(websocket.DefaultDialer)
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}
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// ConnectWithDialer creates a websocket connection with the given ConnectUrl using the dialer.
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// This is racy and error-prone and should not be used. Use any of the New* functions to create a websocket.
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func (wsc *WebSocketClient) ConnectWithDialer(dialer *websocket.Dialer) *AppError {
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var err error
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wsc.Conn, _, err = dialer.Dial(wsc.ConnectUrl, nil)
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if err != nil {
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return NewAppError("Connect", "model.websocket_client.connect_fail.app_error", nil, err.Error(), http.StatusInternalServerError)
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}
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// Super racy and should not be done anyways.
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// All of this needs to be redesigned for v6.
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wsc.configurePingHandling()
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// If it has been closed before, we just restart the writer.
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if atomic.CompareAndSwapInt32(&wsc.closed, 1, 0) {
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wsc.writeChan = make(chan writeMessage)
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wsc.quitWriterChan = make(chan struct{})
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go wsc.writer()
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wsc.resetTimerChan = make(chan struct{})
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wsc.quitPingWatchdog = make(chan struct{})
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}
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wsc.EventChannel = make(chan *WebSocketEvent, 100)
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wsc.ResponseChannel = make(chan *WebSocketResponse, 100)
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wsc.SendMessage(WEBSOCKET_AUTHENTICATION_CHALLENGE, map[string]interface{}{"token": wsc.AuthToken})
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return nil
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}
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// Close closes the websocket client. It is recommended that a closed client should not be
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// reused again. Rather a new client should be created anew.
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func (wsc *WebSocketClient) Close() {
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// CAS to 1 and proceed. Return if already 1.
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if !atomic.CompareAndSwapInt32(&wsc.closed, 0, 1) {
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return
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}
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wsc.quitWriterChan <- struct{}{}
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close(wsc.writeChan)
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// We close the connection, which breaks the reader loop.
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// Then we let the defer block in the reader do further cleanup.
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wsc.Conn.Close()
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}
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// TODO: un-export the Conn so that Write methods go through the writer
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func (wsc *WebSocketClient) writer() {
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for {
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select {
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case msg := <-wsc.writeChan:
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switch msg.msgType {
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case msgTypeJSON:
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wsc.Conn.WriteJSON(msg.data)
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case msgTypePong:
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wsc.Conn.WriteMessage(websocket.PongMessage, []byte{})
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}
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case <-wsc.quitWriterChan:
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return
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}
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}
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}
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// Listen starts the read loop of the websocket client.
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func (wsc *WebSocketClient) Listen() {
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// This loop can exit in 2 conditions:
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// 1. Either the connection breaks naturally.
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// 2. Close was explicitly called, which closes the connection manually.
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//
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// Due to the way the API is written, there is a requirement that a client may NOT
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// call Listen at all and can still call Close and Connect.
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// Therefore, we let the cleanup of the reader stuff rely on closing the connection
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// and then we do the cleanup in the defer block.
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//
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// First, we close some channels and then CAS to 1 and proceed to close the writer chan also.
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// This is needed because then the defer clause does not double-close the writer when (2) happens.
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// But if (1) happens, we set the closed bit, and close the rest of the stuff.
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go func() {
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defer func() {
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close(wsc.EventChannel)
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close(wsc.ResponseChannel)
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close(wsc.quitPingWatchdog)
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close(wsc.resetTimerChan)
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// We CAS to 1 and proceed.
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if !atomic.CompareAndSwapInt32(&wsc.closed, 0, 1) {
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return
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}
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wsc.quitWriterChan <- struct{}{}
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close(wsc.writeChan)
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wsc.Conn.Close() // This can most likely be removed. Needs to be checked.
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}()
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var buf bytes.Buffer
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buf.Grow(avgReadMsgSizeBytes)
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for {
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// Reset buffer.
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buf.Reset()
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_, r, err := wsc.Conn.NextReader()
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if err != nil {
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if !websocket.IsCloseError(err, websocket.CloseNormalClosure, websocket.CloseNoStatusReceived) {
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wsc.ListenError = NewAppError("NewWebSocketClient", "model.websocket_client.connect_fail.app_error", nil, err.Error(), http.StatusInternalServerError)
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}
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return
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}
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// Use pre-allocated buffer.
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_, err = buf.ReadFrom(r)
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if err != nil {
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// This should use a different error ID, but en.json is not imported anyways.
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// It's a different bug altogether but we let it be for now.
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// See MM-24520.
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wsc.ListenError = NewAppError("NewWebSocketClient", "model.websocket_client.connect_fail.app_error", nil, err.Error(), http.StatusInternalServerError)
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return
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}
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event := WebSocketEventFromJson(bytes.NewReader(buf.Bytes()))
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if event == nil {
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continue
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}
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if event.IsValid() {
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wsc.EventChannel <- event
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continue
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}
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var response WebSocketResponse
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if err := json.Unmarshal(buf.Bytes(), &response); err == nil && response.IsValid() {
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wsc.ResponseChannel <- &response
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continue
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}
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}
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}()
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}
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func (wsc *WebSocketClient) SendMessage(action string, data map[string]interface{}) {
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req := &WebSocketRequest{}
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req.Seq = wsc.Sequence
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req.Action = action
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req.Data = data
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wsc.Sequence++
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wsc.writeChan <- writeMessage{
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msgType: msgTypeJSON,
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data: req,
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}
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}
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// UserTyping will push a user_typing event out to all connected users
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// who are in the specified channel
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func (wsc *WebSocketClient) UserTyping(channelId, parentId string) {
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data := map[string]interface{}{
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"channel_id": channelId,
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"parent_id": parentId,
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}
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wsc.SendMessage("user_typing", data)
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}
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// GetStatuses will return a map of string statuses using user id as the key
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func (wsc *WebSocketClient) GetStatuses() {
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wsc.SendMessage("get_statuses", nil)
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}
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// GetStatusesByIds will fetch certain user statuses based on ids and return
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// a map of string statuses using user id as the key
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func (wsc *WebSocketClient) GetStatusesByIds(userIds []string) {
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data := map[string]interface{}{
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"user_ids": userIds,
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}
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wsc.SendMessage("get_statuses_by_ids", data)
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}
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func (wsc *WebSocketClient) configurePingHandling() {
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wsc.Conn.SetPingHandler(wsc.pingHandler)
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wsc.pingTimeoutTimer = time.NewTimer(time.Second * (60 + PING_TIMEOUT_BUFFER_SECONDS))
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go wsc.pingWatchdog()
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}
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func (wsc *WebSocketClient) pingHandler(appData string) error {
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if atomic.LoadInt32(&wsc.closed) == 1 {
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return nil
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}
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wsc.resetTimerChan <- struct{}{}
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wsc.writeChan <- writeMessage{
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msgType: msgTypePong,
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}
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return nil
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}
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// pingWatchdog is used to send values to the PingTimeoutChannel whenever a timeout occurs.
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// We use the resetTimerChan from the pingHandler to pass the signal, and then reset the timer
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// after draining it. And if the timer naturally expires, we also extend it to prevent it from
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// being deadlocked when the resetTimerChan case runs. Because timer.Stop would return false,
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// and the code would be forever stuck trying to read from C.
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func (wsc *WebSocketClient) pingWatchdog() {
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for {
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select {
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case <-wsc.resetTimerChan:
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if !wsc.pingTimeoutTimer.Stop() {
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<-wsc.pingTimeoutTimer.C
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}
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wsc.pingTimeoutTimer.Reset(time.Second * (60 + PING_TIMEOUT_BUFFER_SECONDS))
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case <-wsc.pingTimeoutTimer.C:
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wsc.PingTimeoutChannel <- true
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wsc.pingTimeoutTimer.Reset(time.Second * (60 + PING_TIMEOUT_BUFFER_SECONDS))
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case <-wsc.quitPingWatchdog:
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return
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}
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}
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}
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