gocryptotrader/exchanges/stream/websocket_connection.go

package stream

import (
	"bytes"
	"compress/flate"
	"compress/gzip"
	"crypto/rand"
	"encoding/json"
	"fmt"
	"io"
	"math/big"
	"net"
	"net/http"
	"net/url"
	"sync/atomic"
	"time"

	"github.com/gorilla/websocket"
	"github.com/thrasher-corp/gocryptotrader/log"
)

// SendMessageReturnResponse will send a WS message to the connection and wait
// for response
func (w *WebsocketConnection) SendMessageReturnResponse(signature, request interface{}) ([]byte, error) {
	m, err := w.Match.Set(signature)
	if err != nil {
		return nil, err
	}
	defer m.Cleanup()

	b, err := json.Marshal(request)
	if err != nil {
		return nil, fmt.Errorf("error marshaling json for %s: %w", signature, err)
	}

	start := time.Now()
	err = w.SendRawMessage(websocket.TextMessage, b)
	if err != nil {
		return nil, err
	}

	timer := time.NewTimer(w.ResponseMaxLimit)

	select {
	case payload := <-m.C:
		if w.Reporter != nil {
			w.Reporter.Latency(w.ExchangeName, b, time.Since(start))
		}

		return payload, nil
	case <-timer.C:
		timer.Stop()
		return nil, fmt.Errorf("%s websocket connection: timeout waiting for response with signature: %v",
			w.ExchangeName,
			signature)
	}
}

// Dial sets proxy urls and then connects to the websocket
func (w *WebsocketConnection) Dial(dialer *websocket.Dialer, headers http.Header) error {
	if w.ProxyURL != "" {
		proxy, err := url.Parse(w.ProxyURL)
		if err != nil {
			return err
		}
		dialer.Proxy = http.ProxyURL(proxy)
	}

	var err error
	var conStatus *http.Response

	w.Connection, conStatus, err = dialer.Dial(w.URL, headers)
	if err != nil {
		if conStatus != nil {
			return fmt.Errorf("%s websocket connection: %v %v %v Error: %v",
				w.ExchangeName,
				w.URL,
				conStatus,
				conStatus.StatusCode,
				err)
		}
		return fmt.Errorf("%s websocket connection: %v Error: %v",
			w.ExchangeName,
			w.URL,
			err)
	}
	defer conStatus.Body.Close()

	if w.Verbose {
		log.Infof(log.WebsocketMgr,
			"%v Websocket connected to %s\n",
			w.ExchangeName,
			w.URL)
	}
	select {
	case w.Traffic <- struct{}{}:
	default:
	}
	w.setConnectedStatus(true)
	return nil
}

// SendJSONMessage sends a JSON encoded message over the connection
func (w *WebsocketConnection) SendJSONMessage(data interface{}) error {
	if !w.IsConnected() {
		return fmt.Errorf("%s websocket connection: cannot send message to a disconnected websocket",
			w.ExchangeName)
	}

	w.writeControl.Lock()
	defer w.writeControl.Unlock()

	if w.Verbose {
		log.Debugf(log.WebsocketMgr,
			"%s websocket connection: sending message to websocket %+v\n",
			w.ExchangeName,
			data)
	}

	if w.RateLimit > 0 {
		time.Sleep(time.Duration(w.RateLimit) * time.Millisecond)
		if !w.IsConnected() {
			return fmt.Errorf("%v websocket connection: cannot send message to a disconnected websocket",
				w.ExchangeName)
		}
	}
	return w.Connection.WriteJSON(data)
}

// SendRawMessage sends a message over the connection without JSON encoding it
func (w *WebsocketConnection) SendRawMessage(messageType int, message []byte) error {
	if !w.IsConnected() {
		return fmt.Errorf("%v websocket connection: cannot send message to a disconnected websocket",
			w.ExchangeName)
	}

	w.writeControl.Lock()
	defer w.writeControl.Unlock()

	if w.Verbose {
		log.Debugf(log.WebsocketMgr,
			"%v websocket connection: sending message [%s]\n",
			w.ExchangeName,
			message)
	}
	if w.RateLimit > 0 {
		time.Sleep(time.Duration(w.RateLimit) * time.Millisecond)
		if !w.IsConnected() {
			return fmt.Errorf("%v websocket connection: cannot send message to a disconnected websocket",
				w.ExchangeName)
		}
	}
	if !w.IsConnected() {
		return fmt.Errorf("%v websocket connection: cannot send message to a disconnected websocket",
			w.ExchangeName)
	}
	return w.Connection.WriteMessage(messageType, message)
}

// SetupPingHandler will automatically send ping or pong messages based on
// WebsocketPingHandler configuration
func (w *WebsocketConnection) SetupPingHandler(handler PingHandler) {
	if handler.UseGorillaHandler {
		h := func(msg string) error {
			err := w.Connection.WriteControl(handler.MessageType,
				[]byte(msg),
				time.Now().Add(handler.Delay))
			if err == websocket.ErrCloseSent {
				return nil
			} else if e, ok := err.(net.Error); ok && e.Timeout() {
				return nil
			}
			return err
		}
		w.Connection.SetPingHandler(h)
		return
	}
	w.Wg.Add(1)
	defer w.Wg.Done()
	go func() {
		ticker := time.NewTicker(handler.Delay)
		for {
			select {
			case <-w.ShutdownC:
				ticker.Stop()
				return
			case <-ticker.C:
				err := w.SendRawMessage(handler.MessageType, handler.Message)
				if err != nil {
					log.Errorf(log.WebsocketMgr,
						"%v websocket connection: ping handler failed to send message [%s]",
						w.ExchangeName,
						handler.Message)
					return
				}
			}
		}
	}()
}

// setConnectedStatus sets connection status if changed it will return true.
// TODO: Swap out these atomic switches and opt for sync.RWMutex.
func (w *WebsocketConnection) setConnectedStatus(b bool) bool {
	if b {
		return atomic.SwapInt32(&w.connected, 1) == 0
	}
	return atomic.SwapInt32(&w.connected, 0) == 1
}

// IsConnected exposes websocket connection status
func (w *WebsocketConnection) IsConnected() bool {
	return atomic.LoadInt32(&w.connected) == 1
}

// ReadMessage reads messages, can handle text, gzip and binary
func (w *WebsocketConnection) ReadMessage() Response {
	mType, resp, err := w.Connection.ReadMessage()
	if err != nil {
		if IsDisconnectionError(err) {
			if w.setConnectedStatus(false) {
				// NOTE: When w.setConnectedStatus() returns true the underlying
				// state was changed and this infers that the connection was
				// externally closed and an error is reported else Shutdown()
				// method on WebsocketConnection type has been called and can
				// be skipped.
				select {
				case w.readMessageErrors <- err:
				default:
					// bypass if there is no receiver, as this stops it returning
					// when shutdown is called.
					log.Warnf(log.WebsocketMgr,
						"%s failed to relay error: %v",
						w.ExchangeName,
						err)
				}
			}
		}
		return Response{}
	}

	select {
	case w.Traffic <- struct{}{}:
	default: // causes contention, just bypass if there is no receiver.
	}

	var standardMessage []byte
	switch mType {
	case websocket.TextMessage:
		standardMessage = resp
	case websocket.BinaryMessage:
		standardMessage, err = w.parseBinaryResponse(resp)
		if err != nil {
			log.Errorf(log.WebsocketMgr,
				"%v websocket connection: parseBinaryResponse error: %v",
				w.ExchangeName,
				err)
			return Response{}
		}
	}
	if w.Verbose {
		log.Debugf(log.WebsocketMgr,
			"%v websocket connection: message received: %v",
			w.ExchangeName,
			string(standardMessage))
	}
	return Response{Raw: standardMessage, Type: mType}
}

// parseBinaryResponse parses a websocket binary response into a usable byte array
func (w *WebsocketConnection) parseBinaryResponse(resp []byte) ([]byte, error) {
	var reader io.ReadCloser
	var err error
	if len(resp) >= 2 && resp[0] == 31 && resp[1] == 139 { // Detect GZIP
		reader, err = gzip.NewReader(bytes.NewReader(resp))
		if err != nil {
			return nil, err
		}
	} else {
		reader = flate.NewReader(bytes.NewReader(resp))
	}
	standardMessage, err := io.ReadAll(reader)
	if err != nil {
		return nil, err
	}
	return standardMessage, reader.Close()
}

// GenerateMessageID Creates a messageID to checkout
func (w *WebsocketConnection) GenerateMessageID(highPrec bool) int64 {
	var min int64 = 1e8
	var max int64 = 2e8
	if highPrec {
		max = 2e12
		min = 1e12
	}
	// utilization of hard coded positive numbers and default crypto/rand
	// io.reader will panic on error instead of returning
	randomNumber, err := rand.Int(rand.Reader, big.NewInt(max-min+1))
	if err != nil {
		panic(err)
	}
	return randomNumber.Int64() + min
}

// Shutdown shuts down and closes specific connection
func (w *WebsocketConnection) Shutdown() error {
	if w == nil || w.Connection == nil {
		return nil
	}
	w.setConnectedStatus(false)
	return w.Connection.UnderlyingConn().Close()
}

// SetURL sets connection URL
func (w *WebsocketConnection) SetURL(url string) {
	w.URL = url
}

// SetProxy sets connection proxy
func (w *WebsocketConnection) SetProxy(proxy string) {
	w.ProxyURL = proxy
}

// GetURL returns the connection URL
func (w *WebsocketConnection) GetURL() string {
	return w.URL
}