cmd/tailscale: add up --qr to show QR code

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

cmd/tailscale/cli/up.go

@@ -9,6 +9,7 @@
 	"errors"
 	"flag"
 	"fmt"
+	"log"
 	"os"
 	"reflect"
 	"runtime"
@@ -18,6 +19,7 @@
 
 	shellquote "github.com/kballard/go-shellquote"
 	"github.com/peterbourgon/ff/v3/ffcli"
+	qrcode "github.com/skip2/go-qrcode"
 	"inet.af/netaddr"
 	"tailscale.com/client/tailscale"
 	"tailscale.com/ipn"
@@ -63,6 +65,7 @@ func effectiveGOOS() string {
 func newUpFlagSet(goos string, upArgs *upArgsT) *flag.FlagSet {
 	upf := flag.NewFlagSet("up", flag.ExitOnError)
 
+	upf.BoolVar(&upArgs.qr, "qr", false, "show QR code for login URLs")
 	upf.BoolVar(&upArgs.forceReauth, "force-reauth", false, "force reauthentication")
 	upf.BoolVar(&upArgs.reset, "reset", false, "reset unspecified settings to their default values")
 
@@ -99,6 +102,7 @@ func defaultNetfilterMode() string {
 }
 
 type upArgsT struct {
+	qr                     bool
 	reset                  bool
 	server                 string
 	acceptRoutes           bool
@@ -445,6 +449,15 @@ func runUp(ctx context.Context, args []string) error {
 		if url := n.BrowseToURL; url != nil && printAuthURL(*url) {
 			printed = true
 			fmt.Fprintf(os.Stderr, "\nTo authenticate, visit:\n\n\t%s\n\n", *url)
+			if upArgs.qr {
+				q, err := qrcode.New(*url, qrcode.Medium)
+				if err != nil {
+					log.Printf("QR code error: %v", err)
+				} else {
+					fmt.Fprintf(os.Stderr, "%s\n", q.ToString(false))
+				}
+
+			}
 		}
 	})
 	// Wait for backend client to be connected so we know
@@ -572,7 +585,7 @@ func addPrefFlagMapping(flagName string, prefNames ...string) {
 // correspond to an ipn.Pref.
 func preflessFlag(flagName string) bool {
 	switch flagName {
-	case "authkey", "force-reauth", "reset":
+	case "authkey", "force-reauth", "reset", "qr":
 		return true
 	}
 	return false

cmd/tailscale/depaware.txt

@@ -7,6 +7,9 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
      💣 github.com/mitchellh/go-ps                                   from tailscale.com/cmd/tailscale/cli+
         github.com/peterbourgon/ff/v3                                from github.com/peterbourgon/ff/v3/ffcli
         github.com/peterbourgon/ff/v3/ffcli                          from tailscale.com/cmd/tailscale/cli
+        github.com/skip2/go-qrcode                                   from tailscale.com/cmd/tailscale/cli
+        github.com/skip2/go-qrcode/bitset                            from github.com/skip2/go-qrcode+
+        github.com/skip2/go-qrcode/reedsolomon                       from github.com/skip2/go-qrcode
         github.com/tailscale/goupnp                                  from github.com/tailscale/goupnp/dcps/internetgateway2+
         github.com/tailscale/goupnp/dcps/internetgateway2            from tailscale.com/net/portmapper
         github.com/tailscale/goupnp/httpu                            from github.com/tailscale/goupnp+
@@ -102,8 +105,9 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         golang.org/x/time/rate                                       from tailscale.com/cmd/tailscale/cli+
         bufio                                                        from compress/flate+
         bytes                                                        from bufio+
-        compress/flate                                               from compress/gzip
+        compress/flate                                               from compress/gzip+
         compress/gzip                                                from net/http
+        compress/zlib                                                from image/png
         container/list                                               from crypto/tls+
         context                                                      from crypto/tls+
         crypto                                                       from crypto/ecdsa+
@@ -140,10 +144,14 @@ tailscale.com/cmd/tailscale dependencies: (generated by github.com/tailscale/dep
         flag                                                         from github.com/peterbourgon/ff/v3+
         fmt                                                          from compress/flate+
         hash                                                         from crypto+
+        hash/adler32                                                 from compress/zlib
         hash/crc32                                                   from compress/gzip+
         hash/maphash                                                 from go4.org/mem
         html                                                         from tailscale.com/ipn/ipnstate+
         html/template                                                from tailscale.com/cmd/tailscale/cli
+        image                                                        from github.com/skip2/go-qrcode+
+        image/color                                                  from github.com/skip2/go-qrcode+
+        image/png                                                    from github.com/skip2/go-qrcode
         io                                                           from bufio+
         io/fs                                                        from crypto/rand+
         io/ioutil                                                    from golang.org/x/sys/cpu+

go.mod

@@ -30,6 +30,7 @@ require (
 	github.com/pborman/getopt v1.1.0
 	github.com/peterbourgon/ff/v3 v3.1.0
 	github.com/pkg/sftp v1.13.4
+	github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e
 	github.com/tailscale/certstore v0.0.0-20210528134328-066c94b793d3
 	github.com/tailscale/depaware v0.0.0-20201214215404-77d1e9757027
 	github.com/tailscale/goexpect v0.0.0-20210902213824-6e8c725cea41

go.sum

@@ -536,6 +536,8 @@ github.com/sirupsen/logrus v1.4.1/go.mod h1:ni0Sbl8bgC9z8RoU9G6nDWqqs/fq4eDPysMB
 github.com/sirupsen/logrus v1.6.0/go.mod h1:7uNnSEd1DgxDLC74fIahvMZmmYsHGZGEOFrfsX/uA88=
 github.com/sirupsen/logrus v1.7.0 h1:ShrD1U9pZB12TX0cVy0DtePoCH97K8EtX+mg7ZARUtM=
 github.com/sirupsen/logrus v1.7.0/go.mod h1:yWOB1SBYBC5VeMP7gHvWumXLIWorT60ONWic61uBYv0=
+github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e h1:MRM5ITcdelLK2j1vwZ3Je0FKVCfqOLp5zO6trqMLYs0=
+github.com/skip2/go-qrcode v0.0.0-20200617195104-da1b6568686e/go.mod h1:XV66xRDqSt+GTGFMVlhk3ULuV0y9ZmzeVGR4mloJI3M=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d h1:zE9ykElWQ6/NYmHa3jpm/yHnI4xSofP+UP6SpjHcSeM=
 github.com/smartystreets/assertions v0.0.0-20180927180507-b2de0cb4f26d/go.mod h1:OnSkiWE9lh6wB0YB77sQom3nweQdgAjqCqsofrRNTgc=
 github.com/smartystreets/goconvey v1.6.4 h1:fv0U8FUIMPNf1L9lnHLvLhgicrIVChEkdzIKYqbNC9s=