|
| 1 | +package websocket |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "encoding/json" |
| 6 | + "fmt" |
| 7 | + "log/slog" |
| 8 | + "net/http" |
| 9 | + "net/url" |
| 10 | + "sync" |
| 11 | + "time" |
| 12 | + |
| 13 | + "github.com/gorilla/websocket" |
| 14 | +) |
| 15 | + |
| 16 | +const ( |
| 17 | + // Time allowed to write a message to the peer. |
| 18 | + writeWait = 10 * time.Second |
| 19 | + |
| 20 | + // Time allowed to read the next pong message from the peer. |
| 21 | + pongWait = 60 * time.Second |
| 22 | + |
| 23 | + // Send pings to peer with this period. Must be less than pongWait. |
| 24 | + pingPeriod = (pongWait * 9) / 10 |
| 25 | + |
| 26 | + // Maximum message size allowed from peer. |
| 27 | + maxMessageSize = 16384 // 16 KB |
| 28 | +) |
| 29 | + |
| 30 | +// MessageHandler is a function that processes a message received from a websocket connection. |
| 31 | +type MessageHandler func(msgType int, msg []byte) error |
| 32 | + |
| 33 | +type APIErrorResponse struct { |
| 34 | + Error string `json:"error"` |
| 35 | + Details string `json:"details"` |
| 36 | +} |
| 37 | + |
| 38 | +// NewReader creates a new websocket reader. The reader will pass on any message it receives to the |
| 39 | +// handler function. The handler function should return an error if it fails to process the message. |
| 40 | +func NewReader(ctx context.Context, baseURL, pth, token string, handler MessageHandler) (*Reader, error) { |
| 41 | + parsedURL, err := url.Parse(baseURL) |
| 42 | + if err != nil { |
| 43 | + return nil, err |
| 44 | + } |
| 45 | + |
| 46 | + wsScheme := "ws" |
| 47 | + if parsedURL.Scheme == "https" { |
| 48 | + wsScheme = "wss" |
| 49 | + } |
| 50 | + u := url.URL{Scheme: wsScheme, Host: parsedURL.Host, Path: pth} |
| 51 | + header := http.Header{} |
| 52 | + header.Add("Authorization", fmt.Sprintf("Bearer %s", token)) |
| 53 | + |
| 54 | + return &Reader{ |
| 55 | + ctx: ctx, |
| 56 | + url: u, |
| 57 | + header: header, |
| 58 | + handler: handler, |
| 59 | + done: make(chan struct{}), |
| 60 | + }, nil |
| 61 | +} |
| 62 | + |
| 63 | +type Reader struct { |
| 64 | + ctx context.Context |
| 65 | + url url.URL |
| 66 | + header http.Header |
| 67 | + |
| 68 | + done chan struct{} |
| 69 | + running bool |
| 70 | + |
| 71 | + handler MessageHandler |
| 72 | + |
| 73 | + conn *websocket.Conn |
| 74 | + mux sync.Mutex |
| 75 | + writeMux sync.Mutex |
| 76 | +} |
| 77 | + |
| 78 | +func (w *Reader) Stop() { |
| 79 | + w.mux.Lock() |
| 80 | + defer w.mux.Unlock() |
| 81 | + if !w.running { |
| 82 | + return |
| 83 | + } |
| 84 | + w.conn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, "")) |
| 85 | + w.conn.Close() |
| 86 | + close(w.done) |
| 87 | + w.running = false |
| 88 | +} |
| 89 | + |
| 90 | +func (w *Reader) Done() <-chan struct{} { |
| 91 | + return w.done |
| 92 | +} |
| 93 | + |
| 94 | +func (w *Reader) WriteMessage(messageType int, data []byte) error { |
| 95 | + // The websocket package does not support concurrent writes and panics if it |
| 96 | + // detects that one has occurred, so we need to lock the writeMux to prevent |
| 97 | + // concurrent writes to the same connection. |
| 98 | + w.writeMux.Lock() |
| 99 | + defer w.writeMux.Unlock() |
| 100 | + if !w.running { |
| 101 | + return fmt.Errorf("websocket is not running") |
| 102 | + } |
| 103 | + if err := w.conn.SetWriteDeadline(time.Now().Add(writeWait)); err != nil { |
| 104 | + return err |
| 105 | + } |
| 106 | + return w.conn.WriteMessage(messageType, data) |
| 107 | +} |
| 108 | + |
| 109 | +func (w *Reader) Start() error { |
| 110 | + w.mux.Lock() |
| 111 | + defer w.mux.Unlock() |
| 112 | + if w.running { |
| 113 | + return nil |
| 114 | + } |
| 115 | + |
| 116 | + c, response, err := websocket.DefaultDialer.Dial(w.url.String(), w.header) |
| 117 | + if err != nil { |
| 118 | + var resp APIErrorResponse |
| 119 | + var msg string |
| 120 | + var status string |
| 121 | + if response != nil { |
| 122 | + if response.Body != nil { |
| 123 | + if err := json.NewDecoder(response.Body).Decode(&resp); err == nil { |
| 124 | + msg = resp.Details |
| 125 | + } |
| 126 | + } |
| 127 | + status = response.Status |
| 128 | + } |
| 129 | + return fmt.Errorf("failed to stream logs: %q %s (%s)", err, msg, status) |
| 130 | + } |
| 131 | + w.conn = c |
| 132 | + w.running = true |
| 133 | + go w.loop() |
| 134 | + go w.handlerReader() |
| 135 | + return nil |
| 136 | +} |
| 137 | + |
| 138 | +func (w *Reader) handlerReader() { |
| 139 | + defer w.Stop() |
| 140 | + w.writeMux.Lock() |
| 141 | + w.conn.SetReadLimit(maxMessageSize) |
| 142 | + w.conn.SetReadDeadline(time.Now().Add(pongWait)) |
| 143 | + w.conn.SetPongHandler(func(string) error { w.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil }) |
| 144 | + w.writeMux.Unlock() |
| 145 | + for { |
| 146 | + msgType, message, err := w.conn.ReadMessage() |
| 147 | + if err != nil { |
| 148 | + if IsErrorOfInterest(err) { |
| 149 | + // TODO(gabriel-samfira): we should allow for an error channel that can be used to signal |
| 150 | + // the caller that the connection has been closed. |
| 151 | + slog.With(slog.Any("error", err)).Error("reading log message") |
| 152 | + } |
| 153 | + return |
| 154 | + } |
| 155 | + if w.handler != nil { |
| 156 | + if err := w.handler(msgType, message); err != nil { |
| 157 | + slog.With(slog.Any("error", err)).Error("handling log message") |
| 158 | + } |
| 159 | + } |
| 160 | + } |
| 161 | +} |
| 162 | + |
| 163 | +func (w *Reader) loop() { |
| 164 | + defer w.Stop() |
| 165 | + ticker := time.NewTicker(pingPeriod) |
| 166 | + defer ticker.Stop() |
| 167 | + for { |
| 168 | + select { |
| 169 | + case <-w.ctx.Done(): |
| 170 | + return |
| 171 | + case <-w.Done(): |
| 172 | + return |
| 173 | + case <-ticker.C: |
| 174 | + w.writeMux.Lock() |
| 175 | + w.conn.SetWriteDeadline(time.Now().Add(writeWait)) |
| 176 | + err := w.conn.WriteMessage(websocket.PingMessage, nil) |
| 177 | + if err != nil { |
| 178 | + w.writeMux.Unlock() |
| 179 | + return |
| 180 | + } |
| 181 | + w.writeMux.Unlock() |
| 182 | + } |
| 183 | + } |
| 184 | +} |
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