[client] Display QR code for device auth login URL (#5415)

client/cmd/login.go

@@ -10,6 +10,7 @@ import (
 
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
+	"golang.org/x/term"
 	"google.golang.org/grpc/codes"
 	gstatus "google.golang.org/grpc/status"
 
@@ -23,6 +24,7 @@ import (
 
 func init() {
 	loginCmd.PersistentFlags().BoolVar(&noBrowser, noBrowserFlag, false, noBrowserDesc)
+	loginCmd.PersistentFlags().BoolVar(&showQR, showQRFlag, false, showQRDesc)
 	loginCmd.PersistentFlags().StringVar(&profileName, profileNameFlag, "", profileNameDesc)
 	loginCmd.PersistentFlags().StringVarP(&configPath, "config", "c", "", "(DEPRECATED) Netbird config file location")
 }
@@ -256,7 +258,7 @@ func doForegroundLogin(ctx context.Context, cmd *cobra.Command, setupKey string,
 }
 
 func handleSSOLogin(ctx context.Context, cmd *cobra.Command, loginResp *proto.LoginResponse, client proto.DaemonServiceClient, pm *profilemanager.ProfileManager) error {
-	openURL(cmd, loginResp.VerificationURIComplete, loginResp.UserCode, noBrowser)
+	openURL(cmd, loginResp.VerificationURIComplete, loginResp.UserCode, noBrowser, showQR)
 
 	resp, err := client.WaitSSOLogin(ctx, &proto.WaitSSOLoginRequest{UserCode: loginResp.UserCode, Hostname: hostName})
 	if err != nil {
@@ -324,7 +326,7 @@ func foregroundGetTokenInfo(ctx context.Context, cmd *cobra.Command, config *pro
 		return nil, fmt.Errorf("getting a request OAuth flow info failed: %v", err)
 	}
 
-	openURL(cmd, flowInfo.VerificationURIComplete, flowInfo.UserCode, noBrowser)
+	openURL(cmd, flowInfo.VerificationURIComplete, flowInfo.UserCode, noBrowser, showQR)
 
 	tokenInfo, err := oAuthFlow.WaitToken(context.TODO(), flowInfo)
 	if err != nil {
@@ -334,7 +336,7 @@ func foregroundGetTokenInfo(ctx context.Context, cmd *cobra.Command, config *pro
 	return &tokenInfo, nil
 }
 
-func openURL(cmd *cobra.Command, verificationURIComplete, userCode string, noBrowser bool) {
+func openURL(cmd *cobra.Command, verificationURIComplete, userCode string, noBrowser, showQR bool) {
 	var codeMsg string
 	if userCode != "" && !strings.Contains(verificationURIComplete, userCode) {
 		codeMsg = fmt.Sprintf("and enter the code %s to authenticate.", userCode)
@@ -348,6 +350,12 @@ func openURL(cmd *cobra.Command, verificationURIComplete, userCode string, noBro
 			verificationURIComplete + " " + codeMsg)
 	}
 
+	if showQR {
+		if f, ok := cmd.OutOrStdout().(*os.File); ok && term.IsTerminal(int(f.Fd())) {
+			printQRCode(f, verificationURIComplete)
+		}
+	}
+
 	cmd.Println("")
 
 	if !noBrowser {

client/cmd/qr.go

@@ -0,0 +1,25 @@
+package cmd
+
+import (
+	"io"
+
+	"github.com/mdp/qrterminal/v3"
+)
+
+// printQRCode prints a QR code for the given URL to the writer.
+// Called only when the user explicitly requests QR output via --qr.
+func printQRCode(w io.Writer, url string) {
+	if url == "" {
+		return
+	}
+	qrterminal.GenerateWithConfig(url, qrterminal.Config{
+		Level:          qrterminal.M,
+		Writer:         w,
+		HalfBlocks:     true,
+		BlackChar:      qrterminal.BLACK_BLACK,
+		WhiteChar:      qrterminal.WHITE_WHITE,
+		BlackWhiteChar: qrterminal.BLACK_WHITE,
+		WhiteBlackChar: qrterminal.WHITE_BLACK,
+		QuietZone:      qrterminal.QUIET_ZONE,
+	})
+}

client/cmd/qr_test.go

@@ -0,0 +1,26 @@
+package cmd
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestPrintQRCode_EmptyURL(t *testing.T) {
+	var buf bytes.Buffer
+
+	printQRCode(&buf, "")
+
+	if buf.Len() != 0 {
+		t.Error("expected no output for empty URL")
+	}
+}
+
+func TestPrintQRCode_WritesOutput(t *testing.T) {
+	var buf bytes.Buffer
+
+	printQRCode(&buf, "https://example.com/auth")
+
+	if buf.Len() == 0 {
+		t.Error("expected QR code output for non-empty URL")
+	}
+}

client/cmd/up.go

@@ -39,6 +39,9 @@ const (
 	noBrowserFlag = "no-browser"
 	noBrowserDesc = "do not open the browser for SSO login"
 
+	showQRFlag = "qr"
+	showQRDesc = "show QR code for the SSO login URL (useful for headless machines without browser access)"
+
 	profileNameFlag = "profile"
 	profileNameDesc = "profile name to use for the login. If not specified, the last used profile will be used."
 )
@@ -48,6 +51,7 @@ var (
 	dnsLabels          []string
 	dnsLabelsValidated domain.List
 	noBrowser          bool
+	showQR             bool
 	profileName        string
 	configPath         string
 
@@ -80,6 +84,7 @@ func init() {
 	)
 
 	upCmd.PersistentFlags().BoolVar(&noBrowser, noBrowserFlag, false, noBrowserDesc)
+	upCmd.PersistentFlags().BoolVar(&showQR, showQRFlag, false, showQRDesc)
 	upCmd.PersistentFlags().StringVar(&profileName, profileNameFlag, "", profileNameDesc)
 	upCmd.PersistentFlags().StringVarP(&configPath, "config", "c", "", "(DEPRECATED) NetBird config file location. ")