go-emlid/cmd/fake-reach/main.go

package main

import (
	"context"
	"fmt"
	"log/slog"
	"net"
	"net/http"
	"os"
	"os/signal"

	"forge.cadoles.com/cadoles/go-emlid/reach/discovery"
	socketio "github.com/googollee/go-socket.io"
	"github.com/grandcat/zeroconf"
	"github.com/pkg/errors"
	sloghttp "github.com/samber/slog-http"
	"github.com/wlynxg/anet"
)

func main() {
	ctx := context.Background()

	server, err := startHTTPServer(ctx)
	if err != nil {
		slog.Error("could not start http server", slog.Any("error", errors.WithStack(err)))
		os.Exit(1)
	}

	defer server.Close()

	service, err := startMDNSService(ctx)
	if err != nil {
		slog.Error("could not start mdns service", slog.Any("error", errors.WithStack(err)))
		os.Exit(1)
	}

	defer service.Shutdown()

	interrupt := make(chan os.Signal, 1)
	signal.Notify(interrupt, os.Interrupt)

	slog.Info("Ctrl+C to interrupt")

	<-interrupt
}

func startHTTPServer(ctx context.Context) (*http.Server, error) {
	mux := http.NewServeMux()

	sioServer := NewSocketIOServer()
	go func() {
		if err := sioServer.Serve(); err != nil {
			slog.Error("could not serve socketio", slog.Any("error", errors.WithStack(err)))
		}
	}()

	sioServer.OnEvent("/", "action", func(s socketio.Conn, msg map[string]any) {
		slog.Info("action event", slog.Any("id", s.ID()), slog.Any("message", msg))

		name, ok := msg["name"]
		if !ok {
			return
		}

		switch name {
		case "reboot":
			if err := s.Close(); err != nil {
				slog.Error("could not close connection", slog.Any("error", errors.WithStack(err)))
			}
		}
	})

	mux.Handle("/socket.io/", sioServer)
	mux.HandleFunc("GET /info", GetInfo)
	mux.HandleFunc("GET /configuration", GetConfiguration)
	mux.HandleFunc("POST /configuration/base_mode/base_coordinates", PostJSON)

	handler := sloghttp.Recovery(mux)
	handler = sloghttp.New(slog.Default())(handler)

	server := &http.Server{
		Addr:    ":8080",
		Handler: handler,
	}

	go func() {
		defer sioServer.Close()

		slog.Info("starting http server", slog.Any("address", server.Addr))

		if err := server.ListenAndServe(); err != nil {
			slog.Error("could not listen and serve http requests", slog.Any("error", errors.WithStack(err)))
		}
	}()

	return server, nil
}

func startMDNSService(ctx context.Context) (*zeroconf.Server, error) {
	hostname, err := os.Hostname()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	ifaces, err := anet.Interfaces()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	ips, err := GetLANIPv4Addrs()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	info := []string{
		fmt.Sprintf("local_name=%s", hostname),
		"device=FakeReach",
		"manufacturer_data=egoHIABggkMnZWSuoy0KAgAA",
	}

	slog.Info("announcing mdns service", slog.Any("ips", ips), slog.Any("info", info))

	server, err := zeroconf.RegisterProxy("Reach", discovery.ReachService, "local.", 8080, hostname, ips, info, ifaces)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return server, nil
}

var (
	_, lanA, _ = net.ParseCIDR("10.0.0.0/8")
	_, lanB, _ = net.ParseCIDR("172.16.0.0/12")
	_, lanC, _ = net.ParseCIDR("192.168.0.0/16")
)

func GetLANIPv4Addrs() ([]string, error) {
	ips := make([]string, 0)

	addrs, err := anet.InterfaceAddrs()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	for _, address := range addrs {
		if ipnet, ok := address.(*net.IPNet); ok && !ipnet.IP.IsLoopback() {
			ipv4 := ipnet.IP.To4()
			if ipv4 == nil {
				continue
			}

			isLAN := lanA.Contains(ipv4) || lanB.Contains(ipv4) || lanC.Contains(ipv4)
			if !isLAN {
				continue
			}

			ips = append(ips, ipv4.String())
		}
	}

	return ips, nil
}