1 files changed, 256 insertions, 0 deletions
diff --git a/pkg/v1/remote/image.go b/pkg/v1/remote/image.go
new file mode 100644
index 0000000..fde6142
--- /dev/null
+++ b/pkg/v1/remote/image.go
@@ -0,0 +1,256 @@
+// 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 remote
+
+import (
+	"bytes"
+	"io"
+	"net/http"
+	"net/url"
+	"sync"
+
+	"github.com/google/go-containerregistry/internal/redact"
+	"github.com/google/go-containerregistry/internal/verify"
+	"github.com/google/go-containerregistry/pkg/name"
+	v1 "github.com/google/go-containerregistry/pkg/v1"
+	"github.com/google/go-containerregistry/pkg/v1/partial"
+	"github.com/google/go-containerregistry/pkg/v1/remote/transport"
+	"github.com/google/go-containerregistry/pkg/v1/types"
+)
+
+var acceptableImageMediaTypes = []types.MediaType{
+	types.DockerManifestSchema2,
+	types.OCIManifestSchema1,
+}
+
+// remoteImage accesses an image from a remote registry
+type remoteImage struct {
+	fetcher
+	manifestLock sync.Mutex // Protects manifest
+	manifest     []byte
+	configLock   sync.Mutex // Protects config
+	config       []byte
+	mediaType    types.MediaType
+	descriptor   *v1.Descriptor
+}
+
+func (r *remoteImage) ArtifactType() (string, error) {
+	// kind of a hack, but RawManifest does appropriate locking/memoization
+	// and makes sure r.descriptor is populated.
+	if _, err := r.RawManifest(); err != nil {
+		return "", err
+	}
+	return r.descriptor.ArtifactType, nil
+}
+
+var _ partial.CompressedImageCore = (*remoteImage)(nil)
+
+// Image provides access to a remote image reference.
+func Image(ref name.Reference, options ...Option) (v1.Image, error) {
+	desc, err := Get(ref, options...)
+	if err != nil {
+		return nil, err
+	}
+
+	return desc.Image()
+}
+
+func (r *remoteImage) MediaType() (types.MediaType, error) {
+	if string(r.mediaType) != "" {
+		return r.mediaType, nil
+	}
+	return types.DockerManifestSchema2, nil
+}
+
+func (r *remoteImage) RawManifest() ([]byte, error) {
+	r.manifestLock.Lock()
+	defer r.manifestLock.Unlock()
+	if r.manifest != nil {
+		return r.manifest, nil
+	}
+
+	// NOTE(jonjohnsonjr): We should never get here because the public entrypoints
+	// do type-checking via remote.Descriptor. I've left this here for tests that
+	// directly instantiate a remoteImage.
+	manifest, desc, err := r.fetchManifest(r.Ref, acceptableImageMediaTypes)
+	if err != nil {
+		return nil, err
+	}
+
+	if r.descriptor == nil {
+		r.descriptor = desc
+	}
+	r.mediaType = desc.MediaType
+	r.manifest = manifest
+	return r.manifest, nil
+}
+
+func (r *remoteImage) RawConfigFile() ([]byte, error) {
+	r.configLock.Lock()
+	defer r.configLock.Unlock()
+	if r.config != nil {
+		return r.config, nil
+	}
+
+	m, err := partial.Manifest(r)
+	if err != nil {
+		return nil, err
+	}
+
+	if m.Config.Data != nil {
+		if err := verify.Descriptor(m.Config); err != nil {
+			return nil, err
+		}
+		r.config = m.Config.Data
+		return r.config, nil
+	}
+
+	body, err := r.fetchBlob(r.context, m.Config.Size, m.Config.Digest)
+	if err != nil {
+		return nil, err
+	}
+	defer body.Close()
+
+	r.config, err = io.ReadAll(body)
+	if err != nil {
+		return nil, err
+	}
+	return r.config, nil
+}
+
+// Descriptor retains the original descriptor from an index manifest.
+// See partial.Descriptor.
+func (r *remoteImage) Descriptor() (*v1.Descriptor, error) {
+	// kind of a hack, but RawManifest does appropriate locking/memoization
+	// and makes sure r.descriptor is populated.
+	_, err := r.RawManifest()
+	return r.descriptor, err
+}
+
+// remoteImageLayer implements partial.CompressedLayer
+type remoteImageLayer struct {
+	ri     *remoteImage
+	digest v1.Hash
+}
+
+// Digest implements partial.CompressedLayer
+func (rl *remoteImageLayer) Digest() (v1.Hash, error) {
+	return rl.digest, nil
+}
+
+// Compressed implements partial.CompressedLayer
+func (rl *remoteImageLayer) Compressed() (io.ReadCloser, error) {
+	urls := []url.URL{rl.ri.url("blobs", rl.digest.String())}
+
+	// Add alternative layer sources from URLs (usually none).
+	d, err := partial.BlobDescriptor(rl, rl.digest)
+	if err != nil {
+		return nil, err
+	}
+
+	if d.Data != nil {
+		return verify.ReadCloser(io.NopCloser(bytes.NewReader(d.Data)), d.Size, d.Digest)
+	}
+
+	// We don't want to log binary layers -- this can break terminals.
+	ctx := redact.NewContext(rl.ri.context, "omitting binary blobs from logs")
+
+	for _, s := range d.URLs {
+		u, err := url.Parse(s)
+		if err != nil {
+			return nil, err
+		}
+		urls = append(urls, *u)
+	}
+
+	// The lastErr for most pulls will be the same (the first error), but for
+	// foreign layers we'll want to surface the last one, since we try to pull
+	// from the registry first, which would often fail.
+	// TODO: Maybe we don't want to try pulling from the registry first?
+	var lastErr error
+	for _, u := range urls {
+		req, err := http.NewRequest(http.MethodGet, u.String(), nil)
+		if err != nil {
+			return nil, err
+		}
+
+		resp, err := rl.ri.Client.Do(req.WithContext(ctx))
+		if err != nil {
+			lastErr = err
+			continue
+		}
+
+		if err := transport.CheckError(resp, http.StatusOK); err != nil {
+			resp.Body.Close()
+			lastErr = err
+			continue
+		}
+
+		return verify.ReadCloser(resp.Body, d.Size, rl.digest)
+	}
+
+	return nil, lastErr
+}
+
+// Manifest implements partial.WithManifest so that we can use partial.BlobSize below.
+func (rl *remoteImageLayer) Manifest() (*v1.Manifest, error) {
+	return partial.Manifest(rl.ri)
+}
+
+// MediaType implements v1.Layer
+func (rl *remoteImageLayer) MediaType() (types.MediaType, error) {
+	bd, err := partial.BlobDescriptor(rl, rl.digest)
+	if err != nil {
+		return "", err
+	}
+
+	return bd.MediaType, nil
+}
+
+// Size implements partial.CompressedLayer
+func (rl *remoteImageLayer) Size() (int64, error) {
+	// Look up the size of this digest in the manifest to avoid a request.
+	return partial.BlobSize(rl, rl.digest)
+}
+
+// ConfigFile implements partial.WithManifestAndConfigFile so that we can use partial.BlobToDiffID below.
+func (rl *remoteImageLayer) ConfigFile() (*v1.ConfigFile, error) {
+	return partial.ConfigFile(rl.ri)
+}
+
+// DiffID implements partial.WithDiffID so that we don't recompute a DiffID that we already have
+// available in our ConfigFile.
+func (rl *remoteImageLayer) DiffID() (v1.Hash, error) {
+	return partial.BlobToDiffID(rl, rl.digest)
+}
+
+// Descriptor retains the original descriptor from an image manifest.
+// See partial.Descriptor.
+func (rl *remoteImageLayer) Descriptor() (*v1.Descriptor, error) {
+	return partial.BlobDescriptor(rl, rl.digest)
+}
+
+// See partial.Exists.
+func (rl *remoteImageLayer) Exists() (bool, error) {
+	return rl.ri.blobExists(rl.digest)
+}
+
+// LayerByDigest implements partial.CompressedLayer
+func (r *remoteImage) LayerByDigest(h v1.Hash) (partial.CompressedLayer, error) {
+	return &remoteImageLayer{
+		ri:     r,
+		digest: h,
+	}, nil
+}