Validate current generation of WSL2 with user-mode-networking

Fail with a helpful message when older version is present.

[NO NEW TESTS NEEDED]

Signed-off-by: Jason T. Greene <[email protected]>

pkg/machine/wsl/machine.go

@@ -338,6 +338,12 @@ func (v *MachineVM) Init(opts machine.InitOptions) (bool, error) {
 	v.Rootful = opts.Rootful
 	v.Version = currentMachineVersion
 
+	if v.UserModeNetworking {
+		if err := verifyWSLUserModeCompat(); err != nil {
+			return false, err
+		}
+	}
+
 	if err := downloadDistro(v, opts); err != nil {
 		return false, err
 	}

pkg/machine/wsl/usermodenet.go

@@ -10,6 +10,7 @@ import (
 	"path/filepath"
 
 	"github.com/containers/podman/v4/pkg/machine"
+	"github.com/containers/podman/v4/pkg/machine/wsl/wutil"
 	"github.com/containers/podman/v4/pkg/specgen"
 	"github.com/sirupsen/logrus"
 )
@@ -53,6 +54,21 @@ ip route add $ROUTE
 rm -rf /mnt/wsl/podman-usermodenet
 `
 
+func verifyWSLUserModeCompat() error {
+	if wutil.IsWSLStoreVersionInstalled() {
+		return nil
+	}
+
+	prefix := ""
+	if !winVersionAtLeast(10, 0, 19043) {
+		prefix = "upgrade to 22H2, "
+	}
+
+	return fmt.Errorf("user-mode networking requires a newer version of WSL: "+
+		"%sapply all outstanding windows updates, and then run `wsl --update`",
+		prefix)
+}
+
 func (v *MachineVM) startUserModeNetworking() error {
 	if !v.UserModeNetworking {
 		return nil
@@ -299,6 +315,10 @@ func (v *MachineVM) obtainUserModeNetLock() (*fileLock, error) {
 }
 
 func changeDistUserModeNetworking(dist string, user string, image string, enable bool) error {
+	if err := verifyWSLUserModeCompat(); err != nil {
+		return err
+	}
+
 	// Only install if user-mode is being enabled and there was an image path passed
 	if enable && len(image) > 0 {
 		if err := installUserModeDist(dist, image); err != nil {

pkg/machine/wsl/wutil/wutil.go

@@ -5,6 +5,7 @@ package wutil
 
 import (
 	"bufio"
+	"io"
 	"os/exec"
 	"strings"
 	"syscall"
@@ -37,19 +38,41 @@ func IsWSLInstalled() bool {
 	if err = cmd.Start(); err != nil {
 		return false
 	}
-	scanner := bufio.NewScanner(transform.NewReader(out, unicode.UTF16(unicode.LittleEndian, unicode.UseBOM).NewDecoder()))
-	result := true
-	for scanner.Scan() {
-		line := scanner.Text()
-		// Windows 11 does not set an error exit code when a kernel is not avail
-		if strings.Contains(line, "kernel file is not found") {
-			result = false
-			break
-		}
+
+	kernelNotFound := matchOutputLine(out, "kernel file is not found")
+
+	if err := cmd.Wait(); err != nil {
+		return false
 	}
-	if err := cmd.Wait(); !result || err != nil {
+
+	return !kernelNotFound
+}
+
+func IsWSLStoreVersionInstalled() bool {
+	cmd := SilentExecCmd("wsl", "--version")
+	out, err := cmd.StdoutPipe()
+	cmd.Stderr = nil
+	if err != nil {
+		return false
+	}
+	if err = cmd.Start(); err != nil {
+		return false
+	}
+	hasVersion := matchOutputLine(out, "WSL version:")
+	if err := cmd.Wait(); err != nil {
 		return false
 	}
 
-	return true
+	return hasVersion
+}
+
+func matchOutputLine(output io.ReadCloser, match string) bool {
+	scanner := bufio.NewScanner(transform.NewReader(output, unicode.UTF16(unicode.LittleEndian, unicode.UseBOM).NewDecoder()))
+	for scanner.Scan() {
+		line := scanner.Text()
+		if strings.Contains(line, match) {
+			return true
+		}
+	}
+	return false
 }