stratux/1090es_relay.go

package main

import (
	"bufio"
	"fmt"
	"net"
	"strconv"
	"strings"
	"sync"
	"time"
)

const (
	ipadAddr        = "192.168.10.255:49002"
	dump1090Addr    = "127.0.0.1:30003"
	maxDatagramSize = 8192
)

type PositionInfo struct {
	lat       string
	lng       string
	alt       string
	hdg       string
	vel       string
	vr        string
	tail      string
	last_seen time.Time
}

func cleanupOldEntries() {
	for icaoDec, pi := range blips {
		s := time.Since(pi.last_seen)
		if s.Seconds() >= float64(15) { // Timeout time.
			//fmt.Printf("REMOVED %d\n", icaoDec)
			delete(blips, icaoDec)
		}
	}
}

func ipadUpdate(mutex *sync.Mutex) {
	addr, err := net.ResolveUDPAddr("udp", ipadAddr)
	if err != nil {
		panic(err)
	}
	outConn, err := net.DialUDP("udp", nil, addr)

	for {
		mutex.Lock()
		cleanupOldEntries()
		for icaoDec, pi := range blips {
			msg := fmt.Sprintf("XTRAFFICMy Sim,%d,%s,%s,%s,%s,1,%s,%s,%s", icaoDec, pi.lat, pi.lng, pi.alt, pi.vr, pi.hdg, pi.vel, pi.tail)
			//fmt.Println(msg)
			outConn.Write([]byte(msg))
		}
		mutex.Unlock()
		time.Sleep(1 * time.Second)
	}
	//			c.Write([]byte("XTRAFFICMy Sim,168,42.503464,-83.622551,3749.9,-213.0,1,68.2,126.0,KS6"))
}

var blips map[int64]PositionInfo

func main() {
	mutex := &sync.Mutex{}
	blips = make(map[int64]PositionInfo)
	go ipadUpdate(mutex)
	for {
		inConn, err := net.Dial("tcp", dump1090Addr)
		if err != nil {
			time.Sleep(1 * time.Second)
			continue
		}
		rdr := bufio.NewReader(inConn)
		for {
			buf, err := rdr.ReadString('\n')
			if err != nil { // Must have disconnected?
				break
			}
			buf = strings.Trim(buf, "\r\n")
			//fmt.Printf("%s\n", buf)
			x := strings.Split(buf, ",")
			//TODO: Add more sophisticated stuff that combines heading/speed updates with the location.
			if len(x) < 22 {
				continue
			}
			icao := x[4]
			icaoDec, err := strconv.ParseInt(icao, 16, 32)
			if err != nil {
				continue
			}
			mutex.Lock()
			// Retrieve previous information on this ICAO code.
			var pi PositionInfo
			if _, ok := blips[icaoDec]; ok {
				pi = blips[icaoDec]
			}

			if x[1] == "3" {
				//MSG,3,111,11111,AC2BB7,111111,2015/07/28,03:59:12.363,2015/07/28,03:59:12.353,,5550,,,42.35847,-83.42212,,,,,,0
				alt := x[11]
				lat := x[14]
				lng := x[15]

				//fmt.Printf("icao=%s, icaoDec=%d, alt=%s, lat=%s, lng=%s\n", icao, icaoDec, alt, lat, lng)
				pi.alt = alt
				pi.lat = lat
				pi.lng = lng
			}
			if x[1] == "4" {
				// MSG,4,111,11111,A3B557,111111,2015/07/28,06:13:36.417,2015/07/28,06:13:36.398,,,414,278,,,-64,,,,,0
				vel := x[12]
				hdg := x[13]
				vr := x[16]

				//fmt.Printf("icao=%s, icaoDec=%d, vel=%s, hdg=%s, vr=%s\n", icao, icaoDec, vel, hdg, vr)
				pi.vel = vel
				pi.hdg = hdg
				pi.vr = vr
			}
			if x[1] == "1" {
				// MSG,1,,,%02X%02X%02X,,,,,,%s,,,,,,,,0,0,0,0
				tail := x[10]
				pi.tail = tail
			}

			// Update "last seen" (any type of message).
			pi.last_seen = time.Now()

			blips[icaoDec] = pi // Update information on this ICAO code.
			mutex.Unlock()
		}
	}
}