Refactoring modules

modules/api_rest/api_rest_ws.go

@@ -0,0 +1,118 @@
+package api_rest
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+	"time"
+
+	"github.com/bettercap/bettercap/log"
+	"github.com/bettercap/bettercap/session"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	// Time allowed to write an event to the client.
+	writeWait = 10 * time.Second
+	// Time allowed to read the next pong message from the client.
+	pongWait = 60 * time.Second
+	// Send pings to client with this period. Must be less than pongWait.
+	pingPeriod = (pongWait * 9) / 10
+)
+
+func (api *RestAPI) streamEvent(ws *websocket.Conn, event session.Event) error {
+	msg, err := json.Marshal(event)
+	if err != nil {
+		log.Error("Error while creating websocket message: %s", err)
+		return err
+	}
+
+	ws.SetWriteDeadline(time.Now().Add(writeWait))
+	if err := ws.WriteMessage(websocket.TextMessage, msg); err != nil {
+		if !strings.Contains(err.Error(), "closed connection") {
+			log.Error("Error while writing websocket message: %s", err)
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (api *RestAPI) sendPing(ws *websocket.Conn) error {
+	ws.SetWriteDeadline(time.Now().Add(writeWait))
+	if err := ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
+		log.Error("Error while writing websocket ping message: %s", err)
+		return err
+	}
+	return nil
+}
+
+func (api *RestAPI) streamWriter(ws *websocket.Conn, w http.ResponseWriter, r *http.Request) {
+	defer ws.Close()
+
+	// first we stream what we already have
+	events := session.I.Events.Sorted()
+	n := len(events)
+	if n > 0 {
+		log.Debug("Sending %d events.", n)
+		for _, event := range events {
+			if err := api.streamEvent(ws, event); err != nil {
+				return
+			}
+		}
+	}
+
+	session.I.Events.Clear()
+
+	log.Debug("Listening for events and streaming to ws endpoint ...")
+
+	pingTicker := time.NewTicker(pingPeriod)
+	listener := session.I.Events.Listen()
+	defer session.I.Events.Unlisten(listener)
+
+	for {
+		select {
+		case <-pingTicker.C:
+			if err := api.sendPing(ws); err != nil {
+				return
+			}
+		case event := <-listener:
+			if err := api.streamEvent(ws, event); err != nil {
+				return
+			}
+		case <-api.quit:
+			log.Info("Stopping websocket events streamer ...")
+			return
+		}
+	}
+}
+
+func (api *RestAPI) streamReader(ws *websocket.Conn) {
+	defer ws.Close()
+	ws.SetReadLimit(512)
+	ws.SetReadDeadline(time.Now().Add(pongWait))
+	ws.SetPongHandler(func(string) error { ws.SetReadDeadline(time.Now().Add(pongWait)); return nil })
+	for {
+		_, _, err := ws.ReadMessage()
+		if err != nil {
+			log.Debug("Closing websocket reader.")
+			break
+		}
+	}
+}
+
+func (api *RestAPI) startStreamingEvents(w http.ResponseWriter, r *http.Request) {
+	ws, err := api.upgrader.Upgrade(w, r, nil)
+	if err != nil {
+		if _, ok := err.(websocket.HandshakeError); !ok {
+			log.Error("Error while updating api.rest connection to websocket: %s", err)
+		}
+		return
+	}
+
+	log.Debug("Websocket streaming started for %s", r.RemoteAddr)
+
+	go api.streamWriter(ws, w, r)
+	api.streamReader(ws)
+}