conn.go

package main

import (
	"log"
	"net/http"
	"net/url"
	"strings"
	"time"

	"github.com/gorilla/websocket"
)

const (
	// Time allowed to write a message to the peer.
	writeWait = 10 * time.Second

	// Time allowed to read the next pong message from the peer.
	pongWait = 60 * time.Second

	// Send pings to peer with this period. Must be less than pongWait.
	pingPeriod = (pongWait * 9) / 10

	// 20MB maximum message size allowed from peer.
	maxMessageSize = 20971520
)

var upgrader = websocket.Upgrader{
	ReadBufferSize:  1024,
	WriteBufferSize: 1024,
	CheckOrigin: func(r *http.Request) bool {
		origin := r.Header["Origin"]

		if len(origin) == 0 {
			return true
		}

		u, err := url.Parse(origin[0])
		if err != nil {
			return false
		}

		// Allow development from other localhost connections
		if strings.Contains(u.Host, "localhost:") {
			return true
		}

		return strings.ToLower(u.Host) == strings.ToLower(r.Host)
	},
}

// connection is an middleman between the websocket connection and the hub.
type connection struct {
	// The websocket connection.
	ws *websocket.Conn

	// Buffered channel of outbound messages.
	send chan []byte
}

// readPump pumps messages from the websocket connection to the hub.
func (s subscription) readPump() {
	c := s.conn
	defer func() {
		h.unregister <- s
		c.ws.Close()
	}()
	c.ws.SetReadLimit(maxMessageSize)
	c.ws.SetReadDeadline(time.Now().Add(pongWait))
	c.ws.SetPongHandler(func(string) error { c.ws.SetReadDeadline(time.Now().Add(pongWait)); return nil })
	for {
		_, msg, err := c.ws.ReadMessage()
		if err != nil {
			// log.Printf("other error: %v", err)
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway) {
				log.Printf("error: %v", err)
			}
			break
		}
		m := message{msg, s.room, c}

		// log.Printf("Got message: %#v\n", m)
		log.Printf("Got message in room %v", s.room)

		h.broadcast <- m
	}
}

// write writes a message with the given message type and payload.
func (c *connection) write(mt int, payload []byte) error {
	c.ws.SetWriteDeadline(time.Now().Add(writeWait))
	return c.ws.WriteMessage(mt, payload)
}

// writePump pumps messages from the hub to the websocket connection.
func (s *subscription) writePump() {
	c := s.conn
	ticker := time.NewTicker(pingPeriod)
	defer func() {
		ticker.Stop()
		c.ws.Close()
	}()
	for {
		select {
		case message, ok := <-c.send:
			if !ok {
				c.write(websocket.CloseMessage, []byte{})
				return
			}
			if err := c.write(websocket.TextMessage, message); err != nil {
				return
			}
		case <-ticker.C:
			if err := c.write(websocket.PingMessage, []byte{}); err != nil {
				return
			}
		}
	}
}

// serveWs handles websocket requests from the peer.
func serveWs(w http.ResponseWriter, r *http.Request, room string) {
	ws, err := upgrader.Upgrade(w, r, nil)

	if err != nil {
		log.Println(err)
		return
	}
	c := &connection{send: make(chan []byte, 256), ws: ws}
	s := subscription{c, room}
	h.register <- s
	go s.writePump()
	go s.readPump()
}