images: validate document type before unmarshal

Signed-off-by: Samuel Karp <skarp@amazon.com>

images/image_test.go

@@ -0,0 +1,127 @@
+/*
+   Copyright The containerd Authors.
+
+   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 images
+
+import (
+	"encoding/json"
+	"testing"
+
+	ocispec "github.com/opencontainers/image-spec/specs-go/v1"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestValidateMediaType(t *testing.T) {
+	docTests := []struct {
+		mt    string
+		index bool
+	}{
+		{MediaTypeDockerSchema2Manifest, false},
+		{ocispec.MediaTypeImageManifest, false},
+		{MediaTypeDockerSchema2ManifestList, true},
+		{ocispec.MediaTypeImageIndex, true},
+	}
+	for _, tc := range docTests {
+		t.Run("manifest-"+tc.mt, func(t *testing.T) {
+			manifest := ocispec.Manifest{
+				Config: ocispec.Descriptor{Size: 1},
+				Layers: []ocispec.Descriptor{{Size: 2}},
+			}
+			b, err := json.Marshal(manifest)
+			require.NoError(t, err, "failed to marshal manifest")
+
+			err = validateMediaType(b, tc.mt)
+			if tc.index {
+				assert.Error(t, err, "manifest should not be a valid index")
+			} else {
+				assert.NoError(t, err, "manifest should be valid")
+			}
+		})
+		t.Run("index-"+tc.mt, func(t *testing.T) {
+			index := ocispec.Index{
+				Manifests: []ocispec.Descriptor{{Size: 1}},
+			}
+			b, err := json.Marshal(index)
+			require.NoError(t, err, "failed to marshal index")
+
+			err = validateMediaType(b, tc.mt)
+			if tc.index {
+				assert.NoError(t, err, "index should be valid")
+			} else {
+				assert.Error(t, err, "index should not be a valid manifest")
+			}
+		})
+	}
+
+	mtTests := []struct {
+		mt      string
+		valid   []string
+		invalid []string
+	}{{
+		MediaTypeDockerSchema2Manifest,
+		[]string{MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest},
+		[]string{MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex},
+	}, {
+		ocispec.MediaTypeImageManifest,
+		[]string{MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest},
+		[]string{MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex},
+	}, {
+		MediaTypeDockerSchema2ManifestList,
+		[]string{MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex},
+		[]string{MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest},
+	}, {
+		ocispec.MediaTypeImageIndex,
+		[]string{MediaTypeDockerSchema2ManifestList, ocispec.MediaTypeImageIndex},
+		[]string{MediaTypeDockerSchema2Manifest, ocispec.MediaTypeImageManifest},
+	}}
+	for _, tc := range mtTests {
+		for _, v := range tc.valid {
+			t.Run("valid-"+tc.mt+"-"+v, func(t *testing.T) {
+				doc := struct {
+					MediaType string `json:"mediaType"`
+				}{MediaType: v}
+				b, err := json.Marshal(doc)
+				require.NoError(t, err, "failed to marshal document")
+
+				err = validateMediaType(b, tc.mt)
+				assert.NoError(t, err, "document should be valid")
+			})
+		}
+		for _, iv := range tc.invalid {
+			t.Run("invalid-"+tc.mt+"-"+iv, func(t *testing.T) {
+				doc := struct {
+					MediaType string `json:"mediaType"`
+				}{MediaType: iv}
+				b, err := json.Marshal(doc)
+				require.NoError(t, err, "failed to marshal document")
+
+				err = validateMediaType(b, tc.mt)
+				assert.Error(t, err, "document should not be valid")
+			})
+		}
+	}
+	t.Run("schema1", func(t *testing.T) {
+		doc := struct {
+			FSLayers []string `json:"fsLayers"`
+		}{FSLayers: []string{"1"}}
+		b, err := json.Marshal(doc)
+		require.NoError(t, err, "failed to marshal document")
+
+		err = validateMediaType(b, "")
+		assert.Error(t, err, "document should not be valid")
+	})
+}