1 files changed, 288 insertions, 0 deletions
diff --git a/pkg/v1/validate/image.go b/pkg/v1/validate/image.go
new file mode 100644
index 0000000..94fb767
--- /dev/null
+++ b/pkg/v1/validate/image.go
@@ -0,0 +1,288 @@
+// Copyright 2018 Google LLC All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package validate
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/google/go-cmp/cmp"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
+)
+
+// Image validates that img does not violate any invariants of the image format.
+func Image(img v1.Image, opt ...Option) error {
+	errs := []string{}
+	if err := validateLayers(img, opt...); err != nil {
+		errs = append(errs, fmt.Sprintf("validating layers: %v", err))
+	}
+
+	if err := validateConfig(img); err != nil {
+		errs = append(errs, fmt.Sprintf("validating config: %v", err))
+	}
+
+	if err := validateManifest(img); err != nil {
+		errs = append(errs, fmt.Sprintf("validating manifest: %v", err))
+	}
+
+	if len(errs) != 0 {
+		return errors.New(strings.Join(errs, "\n\n"))
+	}
+	return nil
+}
+
+func validateConfig(img v1.Image) error {
+	cn, err := img.ConfigName()
+	if err != nil {
+		return err
+	}
+
+	rc, err := img.RawConfigFile()
+	if err != nil {
+		return err
+	}
+
+	hash, size, err := v1.SHA256(bytes.NewReader(rc))
+	if err != nil {
+		return err
+	}
+
+	m, err := img.Manifest()
+	if err != nil {
+		return err
+	}
+
+	cf, err := img.ConfigFile()
+	if err != nil {
+		return err
+	}
+
+	pcf, err := v1.ParseConfigFile(bytes.NewReader(rc))
+	if err != nil {
+		return err
+	}
+
+	errs := []string{}
+	if cn != hash {
+		errs = append(errs, fmt.Sprintf("mismatched config digest: ConfigName()=%s, SHA256(RawConfigFile())=%s", cn, hash))
+	}
+
+	if want, got := m.Config.Size, size; want != got {
+		errs = append(errs, fmt.Sprintf("mismatched config size: Manifest.Config.Size()=%d, len(RawConfigFile())=%d", want, got))
+	}
+
+	if diff := cmp.Diff(pcf, cf); diff != "" {
+		errs = append(errs, fmt.Sprintf("mismatched config content: (-ParseConfigFile(RawConfigFile()) +ConfigFile()) %s", diff))
+	}
+
+	if cf.RootFS.Type != "layers" {
+		errs = append(errs, fmt.Sprintf("invalid ConfigFile.RootFS.Type: %q != %q", cf.RootFS.Type, "layers"))
+	}
+
+	if len(errs) != 0 {
+		return errors.New(strings.Join(errs, "\n"))
+	}
+
+	return nil
+}
+
+func validateLayers(img v1.Image, opt ...Option) error {
+	o := makeOptions(opt...)
+
+	layers, err := img.Layers()
+	if err != nil {
+		return err
+	}
+
+	if o.fast {
+		return layersExist(layers)
+	}
+
+	digests := []v1.Hash{}
+	diffids := []v1.Hash{}
+	udiffids := []v1.Hash{}
+	sizes := []int64{}
+	for i, layer := range layers {
+		cl, err := computeLayer(layer)
+		if errors.Is(err, io.ErrUnexpectedEOF) {
+			// Errored while reading tar content of layer because a header or
+			// content section was not the correct length. This is most likely
+			// due to an incomplete download or otherwise interrupted process.
+			m, err := img.Manifest()
+			if err != nil {
+				return fmt.Errorf("undersized layer[%d] content", i)
+			}
+			return fmt.Errorf("undersized layer[%d] content: Manifest.Layers[%d].Size=%d", i, i, m.Layers[i].Size)
+		}
+		if err != nil {
+			return err
+		}
+		// Compute all of these first before we call Config() and Manifest() to allow
+		// for lazy access e.g. for stream.Layer.
+		digests = append(digests, cl.digest)
+		diffids = append(diffids, cl.diffid)
+		udiffids = append(udiffids, cl.uncompressedDiffid)
+		sizes = append(sizes, cl.size)
+	}
+
+	cf, err := img.ConfigFile()
+	if err != nil {
+		return err
+	}
+
+	m, err := img.Manifest()
+	if err != nil {
+		return err
+	}
+
+	errs := []string{}
+	for i, layer := range layers {
+		digest, err := layer.Digest()
+		if err != nil {
+			return err
+		}
+		diffid, err := layer.DiffID()
+		if err != nil {
+			return err
+		}
+		size, err := layer.Size()
+		if err != nil {
+			return err
+		}
+		mediaType, err := layer.MediaType()
+		if err != nil {
+			return err
+		}
+
+		if _, err := img.LayerByDigest(digest); err != nil {
+			return err
+		}
+
+		if _, err := img.LayerByDiffID(diffid); err != nil {
+			return err
+		}
+
+		if digest != digests[i] {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] digest: Digest()=%s, SHA256(Compressed())=%s", i, digest, digests[i]))
+		}
+
+		if m.Layers[i].Digest != digests[i] {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] digest: Manifest.Layers[%d].Digest=%s, SHA256(Compressed())=%s", i, i, m.Layers[i].Digest, digests[i]))
+		}
+
+		if diffid != diffids[i] {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] diffid: DiffID()=%s, SHA256(Gunzip(Compressed()))=%s", i, diffid, diffids[i]))
+		}
+
+		if diffid != udiffids[i] {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] diffid: DiffID()=%s, SHA256(Uncompressed())=%s", i, diffid, udiffids[i]))
+		}
+
+		if cf.RootFS.DiffIDs[i] != diffids[i] {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] diffid: ConfigFile.RootFS.DiffIDs[%d]=%s, SHA256(Gunzip(Compressed()))=%s", i, i, cf.RootFS.DiffIDs[i], diffids[i]))
+		}
+
+		if size != sizes[i] {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] size: Size()=%d, len(Compressed())=%d", i, size, sizes[i]))
+		}
+
+		if m.Layers[i].Size != sizes[i] {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] size: Manifest.Layers[%d].Size=%d, len(Compressed())=%d", i, i, m.Layers[i].Size, sizes[i]))
+		}
+
+		if m.Layers[i].MediaType != mediaType {
+			errs = append(errs, fmt.Sprintf("mismatched layer[%d] mediaType: Manifest.Layers[%d].MediaType=%s, layer.MediaType()=%s", i, i, m.Layers[i].MediaType, mediaType))
+		}
+	}
+	if len(errs) != 0 {
+		return errors.New(strings.Join(errs, "\n"))
+	}
+
+	return nil
+}
+
+func validateManifest(img v1.Image) error {
+	digest, err := img.Digest()
+	if err != nil {
+		return err
+	}
+
+	size, err := img.Size()
+	if err != nil {
+		return err
+	}
+
+	rm, err := img.RawManifest()
+	if err != nil {
+		return err
+	}
+
+	hash, _, err := v1.SHA256(bytes.NewReader(rm))
+	if err != nil {
+		return err
+	}
+
+	m, err := img.Manifest()
+	if err != nil {
+		return err
+	}
+
+	pm, err := v1.ParseManifest(bytes.NewReader(rm))
+	if err != nil {
+		return err
+	}
+
+	errs := []string{}
+	if digest != hash {
+		errs = append(errs, fmt.Sprintf("mismatched manifest digest: Digest()=%s, SHA256(RawManifest())=%s", digest, hash))
+	}
+
+	if diff := cmp.Diff(pm, m); diff != "" {
+		errs = append(errs, fmt.Sprintf("mismatched manifest content: (-ParseManifest(RawManifest()) +Manifest()) %s", diff))
+	}
+
+	if size != int64(len(rm)) {
+		errs = append(errs, fmt.Sprintf("mismatched manifest size: Size()=%d, len(RawManifest())=%d", size, len(rm)))
+	}
+
+	if len(errs) != 0 {
+		return errors.New(strings.Join(errs, "\n"))
+	}
+
+	return nil
+}
+
+func layersExist(layers []v1.Layer) error {
+	errs := []string{}
+	for _, layer := range layers {
+		ok, err := partial.Exists(layer)
+		if err != nil {
+			errs = append(errs, err.Error())
+		}
+		if !ok {
+			errs = append(errs, "layer does not exist")
+		}
+	}
+
+	if len(errs) != 0 {
+		return errors.New(strings.Join(errs, "\n"))
+	}
+
+	return nil
+}