1 files changed, 175 insertions, 0 deletions
diff --git a/pkg/v1/validate/index.go b/pkg/v1/validate/index.go
new file mode 100644
index 0000000..7514dc4
--- /dev/null
+++ b/pkg/v1/validate/index.go
@@ -0,0 +1,175 @@
+// 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"
+	"strings"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-containerregistry/pkg/logs"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+// Index validates that idx does not violate any invariants of the index format.
+func Index(idx v1.ImageIndex, opt ...Option) error {
+	errs := []string{}
+
+	if err := validateChildren(idx, opt...); err != nil {
+		errs = append(errs, fmt.Sprintf("validating children: %v", err))
+	}
+
+	if err := validateIndexManifest(idx); err != nil {
+		errs = append(errs, fmt.Sprintf("validating index manifest: %v", err))
+	}
+
+	if len(errs) != 0 {
+		return errors.New(strings.Join(errs, "\n\n"))
+	}
+	return nil
+}
+
+type withLayer interface {
+	Layer(v1.Hash) (v1.Layer, error)
+}
+
+func validateChildren(idx v1.ImageIndex, opt ...Option) error {
+	manifest, err := idx.IndexManifest()
+	if err != nil {
+		return err
+	}
+
+	errs := []string{}
+	for i, desc := range manifest.Manifests {
+		switch desc.MediaType {
+		case types.OCIImageIndex, types.DockerManifestList:
+			idx, err := idx.ImageIndex(desc.Digest)
+			if err != nil {
+				return err
+			}
+			if err := Index(idx, opt...); err != nil {
+				errs = append(errs, fmt.Sprintf("failed to validate index Manifests[%d](%s): %v", i, desc.Digest, err))
+			}
+			if err := validateMediaType(idx, desc.MediaType); err != nil {
+				errs = append(errs, fmt.Sprintf("failed to validate index MediaType[%d](%s): %v", i, desc.Digest, err))
+			}
+		case types.OCIManifestSchema1, types.DockerManifestSchema2:
+			img, err := idx.Image(desc.Digest)
+			if err != nil {
+				return err
+			}
+			if err := Image(img, opt...); err != nil {
+				errs = append(errs, fmt.Sprintf("failed to validate image Manifests[%d](%s): %v", i, desc.Digest, err))
+			}
+			if err := validateMediaType(img, desc.MediaType); err != nil {
+				errs = append(errs, fmt.Sprintf("failed to validate image MediaType[%d](%s): %v", i, desc.Digest, err))
+			}
+		default:
+			// Workaround for #819.
+			if wl, ok := idx.(withLayer); ok {
+				layer, err := wl.Layer(desc.Digest)
+				if err != nil {
+					return fmt.Errorf("failed to get layer Manifests[%d]: %w", i, err)
+				}
+				if err := Layer(layer, opt...); err != nil {
+					lerr := fmt.Sprintf("failed to validate layer Manifests[%d](%s): %v", i, desc.Digest, err)
+					if desc.MediaType.IsDistributable() {
+						errs = append(errs, lerr)
+					} else {
+						logs.Warn.Printf("nondistributable layer failure: %v", lerr)
+					}
+				}
+			} else {
+				logs.Warn.Printf("Unexpected manifest: %s", desc.MediaType)
+			}
+		}
+	}
+
+	if len(errs) != 0 {
+		return errors.New(strings.Join(errs, "\n"))
+	}
+
+	return nil
+}
+
+type withMediaType interface {
+	MediaType() (types.MediaType, error)
+}
+
+func validateMediaType(i withMediaType, want types.MediaType) error {
+	got, err := i.MediaType()
+	if err != nil {
+		return err
+	}
+	if want != got {
+		return fmt.Errorf("mismatched mediaType: MediaType() = %v != %v", got, want)
+	}
+
+	return nil
+}
+
+func validateIndexManifest(idx v1.ImageIndex) error {
+	digest, err := idx.Digest()
+	if err != nil {
+		return err
+	}
+
+	size, err := idx.Size()
+	if err != nil {
+		return err
+	}
+
+	rm, err := idx.RawManifest()
+	if err != nil {
+		return err
+	}
+
+	hash, _, err := v1.SHA256(bytes.NewReader(rm))
+	if err != nil {
+		return err
+	}
+
+	m, err := idx.IndexManifest()
+	if err != nil {
+		return err
+	}
+
+	pm, err := v1.ParseIndexManifest(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: (-ParseIndexManifest(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
+}