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//
// rhrdtime
//
// The Radio Helsinki Rivendell Time Websocket Server
//
//
// Copyright (C) 2015 Christian Pointner <equinox@helsinki.at>
//
// This file is part of rhrdtime.
//
// rhrdtime is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// any later version.
//
// rhrdtime is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with rhrdtime. If not, see <http://www.gnu.org/licenses/>.
//
package main
import (
"encoding/json"
"flag"
"fmt"
"net/http"
"time"
"github.com/gorilla/websocket"
)
var (
loc *time.Location
)
func init() {
var err error
if loc, err = time.LoadLocation("Europe/Vienna"); err != nil {
fmt.Println("Error while loading loaction Europe/Vienna:", err)
}
}
func getTZOffset(t time.Time) int {
t = t.In(loc)
_, offset := t.Zone()
return offset
}
type ntpMessage struct {
T1 int64 `json:"t1"`
T2 int64 `json:"t2"`
T3 int64 `json:"t3"`
T4 int64 `json:"t4"`
TZOffset int `json:"tz_offset"`
}
func handleNTPClient(w http.ResponseWriter, r *http.Request) {
ws, err := websocket.Upgrade(w, r, nil, 1024, 1024)
if _, ok := err.(websocket.HandshakeError); ok {
http.Error(w, "Not a websocket handshake", 400)
return
} else if err != nil {
fmt.Println(err)
return
}
fmt.Println("Client", ws.RemoteAddr(), "connected")
for {
msgtype, msg, err := ws.ReadMessage()
if err != nil {
fmt.Println("Client", ws.RemoteAddr(), "disconnected:", err)
return
}
now_t2 := time.Now()
if msgtype == websocket.TextMessage {
var n ntpMessage
if err := json.Unmarshal(msg, &n); err != nil {
fmt.Println("Ignoring malformed (", err, ") NTP message from:", ws.RemoteAddr())
continue
}
n.T2 = (now_t2.Unix() * 1000) + int64(now_t2.Nanosecond()/1000000)
n.TZOffset = getTZOffset(now_t2)
now_t3 := time.Now()
n.T3 = (now_t3.Unix() * 1000) + int64(now_t3.Nanosecond()/1000000)
ntp_json, err := json.Marshal(n)
if err != nil {
fmt.Println("Error while encoding to json:", err)
continue
}
if err := ws.WriteMessage(websocket.TextMessage, ntp_json); err != nil {
fmt.Println("Client", ws.RemoteAddr(), "write error:", err)
return
}
}
}
}
func main() {
addr_s := flag.String("addr", ":3000", "addr:port to listen on, default: ':3000'")
help := flag.Bool("help", false, "show usage")
flag.Parse()
if *help {
flag.Usage()
return
}
http.HandleFunc("/ntp", handleNTPClient)
http.ListenAndServe(*addr_s, nil)
}
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