Adapt scp source and target arguments for legacy openssh

This commit restricts use of URIs in scp command to openssh
clients starting from v8.0. On legacy clients the old syntax is
used.

For pre v8.0 openSSH clients only commands involving a single instance
are allowed.

Signed-off-by: David Cassany <dcassany@suse.com>

cmd/limactl/copy.go

@@ -7,6 +7,7 @@ import (
 	"os/exec"
 	"strings"
 
+	"github.com/coreos/go-semver/semver"
 	"github.com/lima-vm/lima/pkg/osutil"
 	"github.com/lima-vm/lima/pkg/sshutil"
 	"github.com/lima-vm/lima/pkg/store"
@@ -51,18 +52,22 @@ func copyAction(cmd *cobra.Command, args []string) error {
 		return err
 	}
 	instDirs := make(map[string]string)
+	scpFlags := []string{}
 	scpArgs := []string{}
 	debug, err := cmd.Flags().GetBool("debug")
 	if err != nil {
 		return err
 	}
 	if debug {
-		scpArgs = append(scpArgs, "-v")
+		scpFlags = append(scpFlags, "-v")
 	}
 	if recursive {
-		scpArgs = append(scpArgs, "-r")
+		scpFlags = append(scpFlags, "-r")
+	}
+	legacySSH := false
+	if sshutil.DetectOpenSSHVersion().LessThan(*semver.New("8.0.0")) {
+		legacySSH = true
 	}
-	scpArgs = append(scpArgs, "-3", "--")
 	for _, arg := range args {
 		path := strings.Split(arg, ":")
 		switch len(path) {
@@ -80,12 +85,22 @@ func copyAction(cmd *cobra.Command, args []string) error {
 			if inst.Status == store.StatusStopped {
 				return fmt.Errorf("instance %q is stopped, run `limactl start %s` to start the instance", instName, instName)
 			}
-			scpArgs = append(scpArgs, fmt.Sprintf("scp://%s@127.0.0.1:%d/%s", u.Username, inst.SSHLocalPort, path[1]))
+			if legacySSH {
+				scpFlags = append(scpFlags, "-P", fmt.Sprintf("%d", inst.SSHLocalPort))
+				scpArgs = append(scpArgs, fmt.Sprintf("%s@127.0.0.1:%s", u.Username, path[1]))
+			} else {
+				scpArgs = append(scpArgs, fmt.Sprintf("scp://%s@127.0.0.1:%d/%s", u.Username, inst.SSHLocalPort, path[1]))
+			}
 			instDirs[instName] = inst.Dir
 		default:
 			return fmt.Errorf("path %q contains multiple colons", arg)
 		}
 	}
+	if legacySSH && len(instDirs) > 1 {
+		return fmt.Errorf("More than one (instance) host is involved in this command, this is only supported for openSSH v8.0 or higher")
+	}
+	scpFlags = append(scpFlags, "-3", "--")
+	scpArgs = append(scpFlags, scpArgs...)
 
 	var sshOpts []string
 	if len(instDirs) == 1 {

pkg/sshutil/sshutil.go

@@ -178,7 +178,7 @@ func CommonOpts(useDotSSH bool) ([]string, error) {
 
 	sshInfo.Do(func() {
 		sshInfo.aesAccelerated = detectAESAcceleration()
-		sshInfo.openSSHVersion = detectOpenSSHVersion()
+		sshInfo.openSSHVersion = DetectOpenSSHVersion()
 	})
 
 	// Only OpenSSH version 8.1 and later support adding ciphers to the front of the default set
@@ -246,7 +246,7 @@ func ParseOpenSSHVersion(version []byte) *semver.Version {
 	return &semver.Version{}
 }
 
-func detectOpenSSHVersion() semver.Version {
+func DetectOpenSSHVersion() semver.Version {
 	var (
 		v      semver.Version
 		stderr bytes.Buffer