image: Add several parsing related helpers

In the next commits, we'll want to parse/validate docker:// URLs,
this commit adds several helpers to make it easier to go from
docker://quay.io/crcont/podman-bundle:4.1.1 to the expected bundle name
(crc_podman_libvirt_4.1.1_amd64.crcbundle)

The requirements on the docker:// URL are very strict, hopefully in the
future we'll relax them, and allow stuff like
quay.io/myorg/my-custom-bundle:latest , and crc will be able to figure
out the corresponding bundle name through the use of labels, or through
an intermediate metadata file.

pkg/crc/image/image.go

@@ -5,7 +5,9 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"net/url"
 	"os"
+	"path"
 	"path/filepath"
 	"strings"
 
@@ -30,6 +32,21 @@ func defaultURI(preset crcpreset.Preset) string {
 	return fmt.Sprintf("//%s/%s:%s", constants.RegistryURI, getImageName(preset), version.GetCRCVersion())
 }
 
+func ValidateURI(uri *url.URL) error {
+	/* For now we are very restrictive on the docker:// URLs we accept, it
+	 * has to contain the bundle version as the tag, and it has to use the
+	 * same image names as the official registry (openshift-bundle,
+	 * okd-bundle, podman-bundle). In future releases, we'll make this more
+	 * flexible
+	 */
+	imageAndTag := strings.Split(path.Base(uri.Path), ":")
+	if len(imageAndTag) != 2 {
+		return fmt.Errorf("invalid %s registry URL, tag is required (such as docker://quay.io/crcont/openshift-bundle:4.11.0)", uri)
+	}
+	_, err := getPresetNameE(imageAndTag[0])
+	return err
+}
+
 func (img *imageHandler) policyContext() (*signature.PolicyContext, error) {
 	policy := &signature.Policy{Default: []signature.PolicyRequirement{signature.NewPRInsecureAcceptAnything()}}
 	policyContext, err := signature.NewPolicyContext(policy)
@@ -95,6 +112,23 @@ func getImageName(preset crcpreset.Preset) string {
 	}
 }
 
+func getPresetNameE(imageName string) (crcpreset.Preset, error) {
+	switch imageName {
+	case "openshift-bundle":
+		return crcpreset.OpenShift, nil
+	case "okd-bundle":
+		return crcpreset.OKD, nil
+	case "podman-bundle":
+		return crcpreset.Podman, nil
+	default:
+		return crcpreset.OpenShift, fmt.Errorf("invalid image name '%s' (Should be openshift-bundle, okd-bundle or podman-bundle)", imageName)
+	}
+}
+func GetPresetName(imageName string) crcpreset.Preset {
+	preset, _ := getPresetNameE(imageName)
+	return preset
+}
+
 func PullBundle(preset crcpreset.Preset, imageURI string) error {
 	if imageURI == "" {
 		imageURI = defaultURI(preset)