cmd/tailscale/cli: [up] move lose-ssh check after other validations

The check was happening too early and in the case of error would wait 5
s and then error out. This makes it so that it does validations before
the SSH check.

Signed-off-by: Maisem Ali <maisem@tailscale.com>

cmd/tailscale/cli/cli_test.go

@@ -789,6 +789,10 @@ func TestUpdatePrefs(t *testing.T) {
 		curPrefs *ipn.Prefs
 		env      upCheckEnv // empty goos means "linux"
 
+		// sshOverTailscale specifies if the cmd being run over SSH over Tailscale.
+		// It is used to test the --accept-risks flag.
+		sshOverTailscale bool
+
 		// checkUpdatePrefsMutations, if non-nil, is run with the new prefs after
 		// updatePrefs might've mutated them (from applyImplicitPrefs).
 		checkUpdatePrefsMutations func(t *testing.T, newPrefs *ipn.Prefs)
@@ -916,15 +920,159 @@ func TestUpdatePrefs(t *testing.T) {
 				}
 			},
 		},
+		{
+			name:  "enable_ssh",
+			flags: []string{"--ssh"},
+			curPrefs: &ipn.Prefs{
+				ControlURL:       "https://login.tailscale.com",
+				Persist:          &persist.Persist{LoginName: "crawshaw.github"},
+				AllowSingleHosts: true,
+				CorpDNS:          true,
+				NetfilterMode:    preftype.NetfilterOn,
+			},
+			wantJustEditMP: &ipn.MaskedPrefs{
+				RunSSHSet:      true,
+				WantRunningSet: true,
+			},
+			checkUpdatePrefsMutations: func(t *testing.T, newPrefs *ipn.Prefs) {
+				if !newPrefs.RunSSH {
+					t.Errorf("RunSSH not set to true")
+				}
+			},
+			env: upCheckEnv{backendState: "Running"},
+		},
+		{
+			name:  "disable_ssh",
+			flags: []string{"--ssh=false"},
+			curPrefs: &ipn.Prefs{
+				ControlURL:       "https://login.tailscale.com",
+				Persist:          &persist.Persist{LoginName: "crawshaw.github"},
+				AllowSingleHosts: true,
+				CorpDNS:          true,
+				RunSSH:           true,
+				NetfilterMode:    preftype.NetfilterOn,
+			},
+			wantJustEditMP: &ipn.MaskedPrefs{
+				RunSSHSet:      true,
+				WantRunningSet: true,
+			},
+			checkUpdatePrefsMutations: func(t *testing.T, newPrefs *ipn.Prefs) {
+				if newPrefs.RunSSH {
+					t.Errorf("RunSSH not set to false")
+				}
+			},
+			env: upCheckEnv{backendState: "Running", upArgs: upArgsT{
+				runSSH: true,
+			}},
+		},
+		{
+			name:             "disable_ssh_over_ssh_no_risk",
+			flags:            []string{"--ssh=false"},
+			sshOverTailscale: true,
+			curPrefs: &ipn.Prefs{
+				ControlURL:       "https://login.tailscale.com",
+				Persist:          &persist.Persist{LoginName: "crawshaw.github"},
+				AllowSingleHosts: true,
+				CorpDNS:          true,
+				NetfilterMode:    preftype.NetfilterOn,
+				RunSSH:           true,
+			},
+			wantJustEditMP: &ipn.MaskedPrefs{
+				RunSSHSet:      true,
+				WantRunningSet: true,
+			},
+			checkUpdatePrefsMutations: func(t *testing.T, newPrefs *ipn.Prefs) {
+				if !newPrefs.RunSSH {
+					t.Errorf("RunSSH not set to true")
+				}
+			},
+			env:          upCheckEnv{backendState: "Running"},
+			wantErrSubtr: "aborted, no changes made",
+		},
+		{
+			name:             "enable_ssh_over_ssh_no_risk",
+			flags:            []string{"--ssh=true"},
+			sshOverTailscale: true,
+			curPrefs: &ipn.Prefs{
+				ControlURL:       "https://login.tailscale.com",
+				Persist:          &persist.Persist{LoginName: "crawshaw.github"},
+				AllowSingleHosts: true,
+				CorpDNS:          true,
+				NetfilterMode:    preftype.NetfilterOn,
+			},
+			wantJustEditMP: &ipn.MaskedPrefs{
+				RunSSHSet:      true,
+				WantRunningSet: true,
+			},
+			checkUpdatePrefsMutations: func(t *testing.T, newPrefs *ipn.Prefs) {
+				if !newPrefs.RunSSH {
+					t.Errorf("RunSSH not set to true")
+				}
+			},
+			env:          upCheckEnv{backendState: "Running"},
+			wantErrSubtr: "aborted, no changes made",
+		},
+		{
+			name:             "enable_ssh_over_ssh",
+			flags:            []string{"--ssh=true", "--accept-risk=lose-ssh"},
+			sshOverTailscale: true,
+			curPrefs: &ipn.Prefs{
+				ControlURL:       "https://login.tailscale.com",
+				Persist:          &persist.Persist{LoginName: "crawshaw.github"},
+				AllowSingleHosts: true,
+				CorpDNS:          true,
+				NetfilterMode:    preftype.NetfilterOn,
+			},
+			wantJustEditMP: &ipn.MaskedPrefs{
+				RunSSHSet:      true,
+				WantRunningSet: true,
+			},
+			checkUpdatePrefsMutations: func(t *testing.T, newPrefs *ipn.Prefs) {
+				if !newPrefs.RunSSH {
+					t.Errorf("RunSSH not set to true")
+				}
+			},
+			env: upCheckEnv{backendState: "Running"},
+		},
+		{
+			name:             "disable_ssh_over_ssh",
+			flags:            []string{"--ssh=false", "--accept-risk=lose-ssh"},
+			sshOverTailscale: true,
+			curPrefs: &ipn.Prefs{
+				ControlURL:       "https://login.tailscale.com",
+				Persist:          &persist.Persist{LoginName: "crawshaw.github"},
+				AllowSingleHosts: true,
+				CorpDNS:          true,
+				RunSSH:           true,
+				NetfilterMode:    preftype.NetfilterOn,
+			},
+			wantJustEditMP: &ipn.MaskedPrefs{
+				RunSSHSet:      true,
+				WantRunningSet: true,
+			},
+			checkUpdatePrefsMutations: func(t *testing.T, newPrefs *ipn.Prefs) {
+				if newPrefs.RunSSH {
+					t.Errorf("RunSSH not set to false")
+				}
+			},
+			env: upCheckEnv{backendState: "Running"},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			if tt.sshOverTailscale {
+				old := getSSHClientEnvVar
+				getSSHClientEnvVar = func() string { return "100.100.100.100 1 1" }
+				t.Cleanup(func() { getSSHClientEnvVar = old })
+			}
 			if tt.env.goos == "" {
 				tt.env.goos = "linux"
 			}
 			tt.env.flagSet = newUpFlagSet(tt.env.goos, &tt.env.upArgs)
 			flags := CleanUpArgs(tt.flags)
-			tt.env.flagSet.Parse(flags)
+			if err := tt.env.flagSet.Parse(flags); err != nil {
+				t.Fatal(err)
+			}
 
 			newPrefs, err := prefsFromUpArgs(tt.env.upArgs, t.Logf, new(ipnstate.Status), tt.env.goos)
 			if err != nil {
@@ -939,6 +1087,8 @@ func TestUpdatePrefs(t *testing.T) {
 					return
 				}
 				t.Fatal(err)
+			} else if tt.wantErrSubtr != "" {
+				t.Fatalf("want error %q, got nil", tt.wantErrSubtr)
 			}
 			if tt.checkUpdatePrefsMutations != nil {
 				tt.checkUpdatePrefsMutations(t, newPrefs)
@@ -952,13 +1102,18 @@ func TestUpdatePrefs(t *testing.T) {
 				justEditMP.Prefs = ipn.Prefs{} // uninteresting
 			}
 			if !reflect.DeepEqual(justEditMP, tt.wantJustEditMP) {
-				t.Logf("justEditMP != wantJustEditMP; following diff omits the Prefs field, which was %+v", oldEditPrefs)
+				t.Logf("justEditMP != wantJustEditMP; following diff omits the Prefs field, which was \n%v", asJSON(oldEditPrefs))
 				t.Fatalf("justEditMP: %v\n\n: ", cmp.Diff(justEditMP, tt.wantJustEditMP, cmpIP))
 			}
 		})
 	}
 }
 
+func asJSON(v any) string {
+	b, _ := json.MarshalIndent(v, "", "\t")
+	return string(b)
+}
+
 var cmpIP = cmp.Comparer(func(a, b netip.Addr) bool {
 	return a == b
 })

cmd/tailscale/cli/down.go

@@ -22,9 +22,13 @@ var downCmd = &ffcli.Command{
 	FlagSet: newDownFlagSet(),
 }
 
+var downArgs struct {
+	acceptedRisks string
+}
+
 func newDownFlagSet() *flag.FlagSet {
 	downf := newFlagSet("down")
-	registerAcceptRiskFlag(downf)
+	registerAcceptRiskFlag(downf, &downArgs.acceptedRisks)
 	return downf
 }
 
@@ -34,7 +38,7 @@ func runDown(ctx context.Context, args []string) error {
 	}
 
 	if isSSHOverTailscale() {
-		if err := presentRiskToUser(riskLoseSSH, `You are connected over Tailscale; this action will disable Tailscale and result in your session disconnecting.`); err != nil {
+		if err := presentRiskToUser(riskLoseSSH, `You are connected over Tailscale; this action will disable Tailscale and result in your session disconnecting.`, downArgs.acceptedRisks); err != nil {
 			return err
 		}
 	}

cmd/tailscale/cli/risks.go

@@ -16,9 +16,8 @@ import (
 )
 
 var (
-	riskTypes     []string
-	acceptedRisks string
-	riskLoseSSH   = registerRiskType("lose-ssh")
+	riskTypes   []string
+	riskLoseSSH = registerRiskType("lose-ssh")
 )
 
 func registerRiskType(riskType string) string {
@@ -28,12 +27,13 @@ func registerRiskType(riskType string) string {
 
 // registerAcceptRiskFlag registers the --accept-risk flag. Accepted risks are accounted for
 // in presentRiskToUser.
-func registerAcceptRiskFlag(f *flag.FlagSet) {
-	f.StringVar(&acceptedRisks, "accept-risk", "", "accept risk and skip confirmation for risk types: "+strings.Join(riskTypes, ","))
+func registerAcceptRiskFlag(f *flag.FlagSet, acceptedRisks *string) {
+	f.StringVar(acceptedRisks, "accept-risk", "", "accept risk and skip confirmation for risk types: "+strings.Join(riskTypes, ","))
 }
 
-// riskAccepted reports whether riskType is in acceptedRisks.
-func riskAccepted(riskType string) bool {
+// isRiskAccepted reports whether riskType is in the comma-separated list of
+// risks in acceptedRisks.
+func isRiskAccepted(riskType, acceptedRisks string) bool {
 	for _, r := range strings.Split(acceptedRisks, ",") {
 		if r == riskType {
 			return true
@@ -49,12 +49,16 @@ var errAborted = errors.New("aborted, no changes made")
 // It is used by the presentRiskToUser function below.
 const riskAbortTimeSeconds = 5
 
-// presentRiskToUser displays the risk message and waits for the user to
-// cancel. It returns errorAborted if the user aborts.
-func presentRiskToUser(riskType, riskMessage string) error {
-	if riskAccepted(riskType) {
+// presentRiskToUser displays the risk message and waits for the user to cancel.
+// It returns errorAborted if the user aborts. In tests it returns errAborted
+// immediately unless the risk has been explicitly accepted.
+func presentRiskToUser(riskType, riskMessage, acceptedRisks string) error {
+	if isRiskAccepted(riskType, acceptedRisks) {
 		return nil
 	}
+	if inTest() {
+		return errAborted
+	}
 	outln(riskMessage)
 	printf("To skip this warning, use --accept-risk=%s\n", riskType)
 

cmd/tailscale/cli/up.go

@@ -116,7 +116,7 @@ func newUpFlagSet(goos string, upArgs *upArgsT) *flag.FlagSet {
 		upf.BoolVar(&upArgs.forceDaemon, "unattended", false, "run in \"Unattended Mode\" where Tailscale keeps running even after the current GUI user logs out (Windows-only)")
 	}
 	upf.DurationVar(&upArgs.timeout, "timeout", 0, "maximum amount of time to wait for tailscaled to enter a Running state; default (0s) blocks forever")
-	registerAcceptRiskFlag(upf)
+	registerAcceptRiskFlag(upf, &upArgs.acceptedRisks)
 	return upf
 }
 
@@ -150,6 +150,7 @@ type upArgsT struct {
 	opUser                 string
 	json                   bool
 	timeout                time.Duration
+	acceptedRisks          string
 }
 
 func (a upArgsT) getAuthKey() (string, error) {
@@ -376,6 +377,21 @@ func updatePrefs(prefs, curPrefs *ipn.Prefs, env upCheckEnv) (simpleUp bool, jus
 		return false, nil, fmt.Errorf("can't change --login-server without --force-reauth")
 	}
 
+	// Do this after validations to avoid the 5s delay if we're going to error
+	// out anyway.
+	wantSSH, haveSSH := env.upArgs.runSSH, curPrefs.RunSSH
+	fmt.Println("wantSSH", wantSSH, "haveSSH", haveSSH)
+	if wantSSH != haveSSH && isSSHOverTailscale() {
+		if wantSSH {
+			err = presentRiskToUser(riskLoseSSH, `You are connected over Tailscale; this action will reroute SSH traffic to Tailscale SSH and will result in your session disconnecting.`, env.upArgs.acceptedRisks)
+		} else {
+			err = presentRiskToUser(riskLoseSSH, `You are connected using Tailscale SSH; this action will result in your session disconnecting.`, env.upArgs.acceptedRisks)
+		}
+		if err != nil {
+			return false, nil, err
+		}
+	}
+
 	tagsChanged := !reflect.DeepEqual(curPrefs.AdvertiseTags, prefs.AdvertiseTags)
 
 	simpleUp = env.flagSet.NFlag() == 0 &&
@@ -475,17 +491,6 @@ func runUp(ctx context.Context, args []string) (retErr error) {
 		curExitNodeIP: exitNodeIP(curPrefs, st),
 	}
 
-	if upArgs.runSSH != curPrefs.RunSSH && isSSHOverTailscale() {
-		if upArgs.runSSH {
-			err = presentRiskToUser(riskLoseSSH, `You are connected over Tailscale; this action will reroute SSH traffic to Tailscale SSH and will result in your session disconnecting.`)
-		} else {
-			err = presentRiskToUser(riskLoseSSH, `You are connected using Tailscale SSH; this action will result in your session disconnecting.`)
-		}
-		if err != nil {
-			return err
-		}
-	}
-
 	defer func() {
 		if retErr == nil {
 			checkSSHUpWarnings(ctx)