Use github.com/brutella/dnssd

So we have "Remove" callback for free
Something like "reachability filter" in Java IDE could be advisable for boards declaring "fake" TTL

Author: facchinm

main.go

@@ -22,11 +22,12 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"strconv"
 	"strings"
 	"sync"
 
 	properties "github.com/arduino/go-properties-orderedmap"
-	"github.com/oleksandr/bonjour"
+	"github.com/brutella/dnssd"
 )
 
 func main() {
@@ -108,19 +109,30 @@ func outputList() {
 	*/
 }
 
-func newBoardPortJSON(port *bonjour.ServiceEntry) *boardPortJSON {
+func newBoardPortJSON(port *dnssd.Service) *boardPortJSON {
 	prefs := properties.NewMap()
 	identificationPrefs := properties.NewMap()
+
+	ip := "127.0.0.1"
+
+	if len(port.IPs) > 0 {
+		ip = port.IPs[0].String()
+	}
+
 	portJSON := &boardPortJSON{
-		Address:             port.AddrIPv4.String(),
-		Label:               port.AddrIPv4.String(),
+		Address:             ip,
+		Label:               ip,
 		Protocol:            "network",
 		ProtocolLabel:       "Network Port",
 		Prefs:               prefs,
 		IdentificationPrefs: identificationPrefs,
 	}
-	portJSON.Prefs.Set("hostname", port.HostName)
-	portJSON.Prefs.Set("text", port.Text[0])
+	portJSON.Prefs.Set("ttl", port.Ttl.String())
+	portJSON.Prefs.Set("hostname", port.Hostname())
+	portJSON.Prefs.Set("port", strconv.Itoa(port.Port))
+	for key, value := range port.Text {
+		portJSON.Prefs.Set(key, value)
+	}
 	return portJSON
 }
 

sync.go

@@ -18,13 +18,14 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
-	"fmt"
-	"log"
 
-	"github.com/oleksandr/bonjour"
+	"github.com/brutella/dnssd"
 )
 
+var service = "_arduino._tcp.local."
+
 type syncOutputJSON struct {
 	EventType string         `json:"eventType"`
 	Port      *boardPortJSON `json:"port"`
@@ -43,32 +44,24 @@ func startSync() (chan<- bool, error) {
 
 	closeChan := make(chan bool)
 
-	resolver, err := bonjour.NewResolver(nil)
-	if err != nil {
-		log.Println("Failed to initialize resolver:", err.Error())
-		return nil, err
+	addFn := func(srv dnssd.Service) {
+		outputSyncMessage(&syncOutputJSON{
+			EventType: "add",
+			Port:      newBoardPortJSON(&srv),
+		})
 	}
 
-	results := make(chan *bonjour.ServiceEntry)
-
-	go func(results chan *bonjour.ServiceEntry, exitCh chan<- bool) {
-		for {
-			for e := range results {
-				log.Printf("%+v", e)
-				if e.AddrIPv4 != nil {
-					fmt.Println(e)
-				}
-			}
-		}
-	}(results, resolver.Exit)
+	remFn := func(srv dnssd.Service) {
+		outputSyncMessage(&syncOutputJSON{
+			EventType: "remove",
+			Port:      newBoardPortJSON(&srv),
+		})
+	}
 
-	// Sample output
-	//2018/12/12 18:05:14 &{ServiceRecord:{Instance:Arduino Service:_arduino._tcp Domain:local serviceName: serviceInstanceName: serviceTypeName:} HostName:Arduino.local. Port:65280 Text:[ssh_upload=no tcp_check=no auth_upload=yes board=uno2018] TTL:120 AddrIPv4:10.130.22.247 AddrIPv6:<nil>}
-	//&{{Arduino _arduino._tcp local   } Arduino.local. 65280 [ssh_upload=no tcp_check=no auth_upload=yes board=uno2018] 120 10.130.22.247 <nil>}
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
 
-	err = resolver.Browse("_arduino._tcp", "", results)
-	if err != nil {
-		log.Println("Failed to browse:", err.Error())
+	if err := dnssd.LookupType(ctx, service, addFn, remFn); err != nil {
 		return nil, err
 	}