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// Copyright 2023 Google LLC All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package remote
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import (
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"bytes"
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"context"
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"errors"
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"io"
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"net/http"
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"strings"
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"github.com/google/go-containerregistry/pkg/name"
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v1 "github.com/google/go-containerregistry/pkg/v1"
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"github.com/google/go-containerregistry/pkg/v1/empty"
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"github.com/google/go-containerregistry/pkg/v1/mutate"
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"github.com/google/go-containerregistry/pkg/v1/remote/transport"
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"github.com/google/go-containerregistry/pkg/v1/types"
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)
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// Referrers returns a list of descriptors that refer to the given manifest digest.
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//
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// The subject manifest doesn't have to exist in the registry for there to be descriptors that refer to it.
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func Referrers(d name.Digest, options ...Option) (v1.ImageIndex, error) {
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o, err := makeOptions(options...)
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if err != nil {
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return nil, err
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}
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return newPuller(o).referrers(o.context, d, o.filter)
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}
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// https://github.com/opencontainers/distribution-spec/blob/main/spec.md#referrers-tag-schema
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func fallbackTag(d name.Digest) name.Tag {
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return d.Context().Tag(strings.Replace(d.DigestStr(), ":", "-", 1))
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}
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func (f *fetcher) fetchReferrers(ctx context.Context, filter map[string]string, d name.Digest) (v1.ImageIndex, error) {
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// Check the Referrers API endpoint first.
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u := f.url("referrers", d.DigestStr())
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, u.String(), nil)
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if err != nil {
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return nil, err
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}
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req.Header.Set("Accept", string(types.OCIImageIndex))
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resp, err := f.client.Do(req)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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if err := transport.CheckError(resp, http.StatusOK, http.StatusNotFound, http.StatusBadRequest); err != nil {
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return nil, err
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}
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var b []byte
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if resp.StatusCode == http.StatusOK {
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b, err = io.ReadAll(resp.Body)
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if err != nil {
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return nil, err
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}
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} else {
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// The registry doesn't support the Referrers API endpoint, so we'll use the fallback tag scheme.
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b, _, err = f.fetchManifest(ctx, fallbackTag(d), []types.MediaType{types.OCIImageIndex})
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var terr *transport.Error
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if errors.As(err, &terr) && terr.StatusCode == http.StatusNotFound {
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// Not found just means there are no attachments yet. Start with an empty manifest.
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return empty.Index, nil
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} else if err != nil {
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return nil, err
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}
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}
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h, sz, err := v1.SHA256(bytes.NewReader(b))
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if err != nil {
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return nil, err
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}
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idx := &remoteIndex{
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fetcher: *f,
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ctx: ctx,
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manifest: b,
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mediaType: types.OCIImageIndex,
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descriptor: &v1.Descriptor{
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Digest: h,
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MediaType: types.OCIImageIndex,
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Size: sz,
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},
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}
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return filterReferrersResponse(filter, idx), nil
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}
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// If filter applied, filter out by artifactType.
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// See https://github.com/opencontainers/distribution-spec/blob/main/spec.md#listing-referrers
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func filterReferrersResponse(filter map[string]string, in v1.ImageIndex) v1.ImageIndex {
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if filter == nil {
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return in
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}
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v, ok := filter["artifactType"]
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if !ok {
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return in
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}
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return mutate.RemoveManifests(in, func(desc v1.Descriptor) bool {
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return desc.ArtifactType != v
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})
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}
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