feat: add Avahi Zeroconf backend

Author: devgianlu

config_schema.json

@@ -169,7 +169,8 @@
           "type": "string",
           "description": "The Zeroconf implementation to use",
           "enum": [
-            "builtin"
+            "builtin",
+            "avahi"
           ],
           "default": "builtin"
         },

go.mod

@@ -3,6 +3,7 @@ module github.com/devgianlu/go-librespot
 go 1.22.2
 
 require (
+	github.com/OpenPrinting/go-avahi v0.0.0-20250813163007-dd9db1c4a6e9
 	github.com/cenkalti/backoff/v4 v4.2.1
 	github.com/devgianlu/shannon v0.0.0-20230613115856-82ec90b7fa7e
 	github.com/godbus/dbus/v5 v5.1.0

go.sum

@@ -1,3 +1,5 @@
+github.com/OpenPrinting/go-avahi v0.0.0-20250813163007-dd9db1c4a6e9 h1:sYwgzNSkvqBnhfhS5THhHdSYt+8aleQBGMLObOOg5vM=
+github.com/OpenPrinting/go-avahi v0.0.0-20250813163007-dd9db1c4a6e9/go.mod h1:1vYkalHi1N1ZQ+Wt7KX7WK8fTS09iwrZnuQjwpsUMCU=
 github.com/cenkalti/backoff v2.2.1+incompatible h1:tNowT99t7UNflLxfYYSlKYsBpXdEet03Pg2g16Swow4=
 github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
 github.com/cenkalti/backoff/v4 v4.2.1 h1:y4OZtCnogmCPw98Zjyt5a6+QwPLGkiQsYW5oUqylYbM=

zeroconf/discovery/avahi.go

@@ -0,0 +1,58 @@
+//go:build linux
+
+package discovery
+
+import (
+	"fmt"
+	"net"
+
+	"github.com/OpenPrinting/go-avahi"
+)
+
+func init() {
+	discoveryServices["avahi"] = &avahiDiscoveryService{}
+}
+
+type avahiDiscoveryService struct {
+	client *avahi.Client
+	group  *avahi.EntryGroup
+}
+
+func (s *avahiDiscoveryService) Register(name, service, domain string, port int, txt []string, ifaces []net.Interface) (err error) {
+	if len(ifaces) > 0 {
+		return fmt.Errorf("avahi discovery does not support specifying interfaces")
+	}
+
+	s.client, err = avahi.NewClient(avahi.ClientLoopbackWorkarounds)
+	if err != nil {
+		return fmt.Errorf("failed to create Avahi client: %w", err)
+	}
+
+	s.group, err = avahi.NewEntryGroup(s.client)
+	if err != nil {
+		return fmt.Errorf("failed to create Avahi entry group: %w", err)
+	}
+
+	if err = s.group.AddService(&avahi.EntryGroupService{
+		IfIdx:        avahi.IfIndexUnspec,
+		Proto:        avahi.ProtocolUnspec,
+		InstanceName: name,
+		SvcType:      service,
+		Domain:       domain,
+		Port:         port,
+		Txt:          txt,
+	}, 0); err != nil {
+		return fmt.Errorf("failed to add service to Avahi entry group: %w", err)
+	}
+
+	if err = s.group.Commit(); err != nil {
+		return fmt.Errorf("failed to commit Avahi entry group: %w", err)
+	}
+
+	return nil
+}
+
+func (s *avahiDiscoveryService) Shutdown() {
+	s.group.Close()
+	s.client.Close()
+}