refactor: improve constant naming and error handling

Author: grishy

avahi/publisher.go

@@ -10,10 +10,10 @@ import (
 )
 
 const (
-	// https://github.com/lathiat/avahi/blob/v0.8/avahi-common/defs.h#L343
-	AVAHI_DNS_CLASS_IN = uint16(0x01)
-	// https://github.com/lathiat/avahi/blob/v0.8/avahi-common/defs.h#L331
-	AVAHI_DNS_TYPE_CNAME = uint16(0x05)
+	// AvahiDNSClassIn from  https://github.com/lathiat/avahi/blob/v0.8/avahi-common/defs.h#L343
+	AvahiDNSClassIn = uint16(0x01)
+	// AvahiDNSTypeCName from https://github.com/lathiat/avahi/blob/v0.8/avahi-common/defs.h#L331
+	AvahiDNSTypeCName = uint16(0x05)
 )
 
 type Publisher struct {
@@ -91,8 +91,8 @@ func (p *Publisher) PublishCNAMES(cnames []string, ttl uint32) error {
 			avahi.ProtoUnspec,
 			uint32(0), // From Avahi Python bindings https://gist.github.com/gdamjan/3168336#file-avahi-alias-py-L42
 			cname,
-			AVAHI_DNS_CLASS_IN,
-			AVAHI_DNS_TYPE_CNAME,
+			AvahiDNSClassIn,
+			AvahiDNSTypeCName,
 			ttl,
 			p.rdataField,
 		)

cmd/cname.go

@@ -2,6 +2,7 @@ package cmd
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log/slog"
 	"time"
@@ -117,7 +118,7 @@ func Cname(ctx context.Context) *cli.Command {
 			cnames := cCtx.Args().Slice()
 
 			if len(cnames) == 0 {
-				return fmt.Errorf("at least one CNAME should be provided")
+				return errors.New("at least one CNAME should be provided")
 			}
 
 			slog.Info("creating publisher")

cmd/subdomain.go

@@ -66,8 +66,8 @@ func reader(ctx context.Context, conn *net.UDPConn) chan *dnsMsg {
 			}
 			slog.Debug("received UDP message", "bytes", bytesRead, "from", remoteAddress)
 
-			if err := dnsMsg.msg.Unpack(buf[:bytesRead]); err != nil {
-				dnsMsg.err = errors.Join(dnsMsg.err, fmt.Errorf("failed to unpack message: %w", err))
+			if unpackErr := dnsMsg.msg.Unpack(buf[:bytesRead]); unpackErr != nil {
+				dnsMsg.err = errors.Join(dnsMsg.err, fmt.Errorf("failed to unpack message: %w", unpackErr))
 				msgCh <- dnsMsg
 				continue
 			}
@@ -81,10 +81,11 @@ func reader(ctx context.Context, conn *net.UDPConn) chan *dnsMsg {
 }
 
 // selectQuestion filters and selects questions with the given FQDN suffix.
-func selectQuestion(fqdn string, qs []dns.Question) (res []string) {
+func selectQuestion(fqdn string, qs []dns.Question) []string {
 	suffix := strings.ToLower("." + fqdn)
 	slog.Debug("filtering DNS questions", "suffix", suffix, "questions", len(qs))
 
+	res := make([]string, 0, len(qs))
 	for _, q := range qs {
 		slog.Debug("processing question", "name", q.Name, "type", dns.TypeToString[q.Qtype])
 
@@ -114,8 +115,8 @@ func runSubdomain(ctx context.Context, publisher *avahi.Publisher, fqdn string,
 		<-ctx.Done()
 		fmt.Println() // Add new line after ^C
 		slog.Info("closing connection")
-		if err := conn.Close(); err != nil {
-			slog.Error("failed to close connection", "error", err)
+		if closeErr := conn.Close(); closeErr != nil {
+			slog.Error("failed to close connection", "error", closeErr)
 		}
 	}()
 
@@ -132,8 +133,8 @@ func runSubdomain(ctx context.Context, publisher *avahi.Publisher, fqdn string,
 
 		if len(found) > 0 {
 			slog.Debug("publishing matching CNAMEs", "count", len(found))
-			if err := publisher.PublishCNAMES(found, ttl); err != nil {
-				return fmt.Errorf("failed to publish CNAMEs: %w", err)
+			if publishErr := publisher.PublishCNAMES(found, ttl); publishErr != nil {
+				return fmt.Errorf("failed to publish CNAMEs: %w", publishErr)
 			}
 		}
 	}

main.go

@@ -22,7 +22,7 @@ const (
 	appName          = "go-avahi-cname"
 )
 
-// Version information set during build
+// Version information set during build.
 var (
 	version = "dev"
 	commit  = "none"
@@ -48,9 +48,9 @@ func runMain() int {
 	return 0
 }
 
-// run starts and configures the CLI application
+// run starts and configures the CLI application.
 func run(ctx context.Context) error {
-	cli.VersionPrinter = func(c *cli.Context) {
+	cli.VersionPrinter = func(_ *cli.Context) {
 		fmt.Print(buildVersion().String())
 	}
 
@@ -61,7 +61,7 @@ func run(ctx context.Context) error {
 		Description: `A tool that helps you create local domain names for your computer by using the Avahi daemon.
 
 It works in two ways:
-1. Automatic mode (use 'subdomain' command): 
+1. Automatic mode (use 'subdomain' command):
    Any subdomain you try to use (like myapp.computer.local) will automatically point to your computer
 
 2. Manual mode (use 'cname' command):
@@ -91,7 +91,7 @@ Need help? Visit https://github.com/grishy/go-avahi-cname`,
 	return app.Run(os.Args)
 }
 
-// handleGracefulShutdown manages graceful shutdown with timeout
+// handleGracefulShutdown manages graceful shutdown with timeout.
 func handleGracefulShutdown(ctx context.Context) {
 	<-ctx.Done()
 	slog.Info("initiating graceful shutdown...")
@@ -108,7 +108,7 @@ func handleGracefulShutdown(ctx context.Context) {
 	}
 }
 
-// setupLogger configures the global structured logger with appropriate settings
+// setupLogger configures the global structured logger with appropriate settings.
 func setupLogger(c *cli.Context) error {
 	w := os.Stdout
 	level := slog.LevelInfo
@@ -127,7 +127,7 @@ func setupLogger(c *cli.Context) error {
 	return nil
 }
 
-// buildVersion constructs version information for the application
+// buildVersion constructs version information for the application.
 func buildVersion() goversion.Info {
 	return goversion.GetVersionInfo(
 		func(i *goversion.Info) {