README.md

Golang bindings for Avahi

Avahi is an implementation of the mDNS protocol. Refer to the Wikipedia article, the website and the GitHub project for further information.

This Go package provides bindings for DBus interfaces exposed by the Avahi daemon.

Install

Install the package like this:

go get https://github.com/holoplot/go-avahi

And then use it in your source code.

import "github.com/holoplot/go-avahi"

Examples

Below are some examples to illustrate the usage of this package. Note that you will need to have a working Avahi installation.

Browsing and resolving

package main

import (
	"log"

	"github.com/godbus/dbus/v5"
	"github.com/holoplot/go-avahi"
)

func cb(event Event) {
	log.Println("Avahi Disconnected")
	// initiate reconnect
}

func main() {
	server, err := avahi.ServerNew(cb)
	if err != nil {
		log.Fatalf("Avahi new failed: %v", err)
	}

	host, err := server.GetHostName()
	if err != nil {
		log.Fatalf("GetHostName() failed: %v", err)
	}
	log.Println("GetHostName()", host)

	fqdn, err := server.GetHostNameFqdn()
	if err != nil {
		log.Fatalf("GetHostNameFqdn() failed: %v", err)
	}
	log.Println("GetHostNameFqdn()", fqdn)

	s, err := server.GetAlternativeHostName(host)
	if err != nil {
		log.Fatalf("GetAlternativeHostName() failed: %v", err)
	}
	log.Println("GetAlternativeHostName()", s)

	i, err := server.GetAPIVersion()
	if err != nil {
		log.Fatalf("GetAPIVersion() failed: %v", err)
	}
	log.Println("GetAPIVersion()", i)

	hn, err := server.ResolveHostName(avahi.InterfaceUnspec, avahi.ProtoUnspec, fqdn, avahi.ProtoUnspec, 0)
	if err != nil {
		log.Fatalf("ResolveHostName() failed: %v", err)
	}
	log.Println("ResolveHostName:", hn)

	db, err := server.DomainBrowserNew(avahi.InterfaceUnspec, avahi.ProtoUnspec, "", avahi.DomainBrowserTypeBrowseDefault, 0)
	if err != nil {
		log.Fatalf("DomainBrowserNew() failed: %v", err)
	}

	stb, err := server.ServiceTypeBrowserNew(avahi.InterfaceUnspec, avahi.ProtoUnspec, "local", 0)
	if err != nil {
		log.Fatalf("ServiceTypeBrowserNew() failed: %v", err)
	}

	sb, err := server.ServiceBrowserNew(avahi.InterfaceUnspec, avahi.ProtoUnspec, "_my-nifty-service._tcp", "local", 0)
	if err != nil {
		log.Fatalf("ServiceBrowserNew() failed: %v", err)
	}

	sr, err := server.ServiceResolverNew(avahi.InterfaceUnspec, avahi.ProtoUnspec, "", "_my-nifty-service._tcp", "local", avahi.ProtoUnspec, 0)
	if err != nil {
		log.Fatalf("ServiceResolverNew() failed: %v", err)
	}

	var domain avahi.Domain
	var service avahi.Service
	var serviceType avahi.ServiceType

	for {
		select {
		case domain = <-db.AddChannel:
			log.Println("DomainBrowser ADD: ", domain)
		case domain = <-db.RemoveChannel:
			log.Println("DomainBrowser REMOVE: ", domain)
		case serviceType = <-stb.AddChannel:
			log.Println("ServiceTypeBrowser ADD: ", serviceType)
		case serviceType = <-stb.RemoveChannel:
			log.Println("ServiceTypeBrowser REMOVE: ", serviceType)
		case service = <-sb.AddChannel:
			log.Println("ServiceBrowser ADD: ", service)

			service, err := server.ResolveService(service.Interface, service.Protocol, service.Name,
				service.Type, service.Domain, avahi.ProtoUnspec, 0)
			if err == nil {
				log.Println(" RESOLVED >>", service.Address)
			}
		case service = <-sb.RemoveChannel:
			log.Println("ServiceBrowser REMOVE: ", service)
		case service = <-sr.FoundChannel:
			log.Println("ServiceResolver FOUND: ", service)
		}
	}
}

Publishing

package main

import (
	"log"

	"github.com/godbus/dbus/v5"
	"github.com/holoplot/go-avahi"
)

func cb(event Event) {
	log.Println("Avahi Disconnected")
	// initiate reconnect
}

func main() {
	a, err := avahi.ServerNew(cb)
	if err != nil {
		log.Fatalf("Avahi new failed: %v", err)
	}

	eg, err := a.EntryGroupNew()
	if err != nil {
		log.Fatalf("EntryGroupNew() failed: %v", err)
	}

	hostname, err := a.GetHostName()
	if err != nil {
		log.Fatalf("GetHostName() failed: %v", err)
	}

	fqdn, err := a.GetHostNameFqdn()
	if err != nil {
		log.Fatalf("GetHostNameFqdn() failed: %v", err)
	}

	err = eg.AddService(avahi.InterfaceUnspec, avahi.ProtoUnspec, 0, hostname, "_my-nifty-service._tcp", "local", fqdn, 1234, nil)
	if err != nil {
		log.Fatalf("AddService() failed: %v", err)
	}

	err = eg.Commit()
	if err != nil {
		log.Fatalf("Commit() failed: %v", err)
	}

	log.Println("Entry published. Hit ^C to exit.")

	for {
		select {}
	}
}

MIT License

See file LICENSE for details.