339 lines
10 KiB
Go
339 lines
10 KiB
Go
package docker
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import (
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"fmt"
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"io"
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"io/ioutil"
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"mime"
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"net/http"
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"net/url"
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"os"
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"strconv"
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"github.com/Sirupsen/logrus"
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"github.com/containers/image/docker/reference"
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"github.com/containers/image/manifest"
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"github.com/containers/image/types"
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"github.com/docker/distribution/registry/client"
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"github.com/opencontainers/go-digest"
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"github.com/pkg/errors"
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)
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type dockerImageSource struct {
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ref dockerReference
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requestedManifestMIMETypes []string
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c *dockerClient
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// State
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cachedManifest []byte // nil if not loaded yet
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cachedManifestMIMEType string // Only valid if cachedManifest != nil
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}
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// newImageSource creates a new ImageSource for the specified image reference,
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// asking the backend to use a manifest from requestedManifestMIMETypes if possible.
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// nil requestedManifestMIMETypes means manifest.DefaultRequestedManifestMIMETypes.
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// The caller must call .Close() on the returned ImageSource.
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func newImageSource(ctx *types.SystemContext, ref dockerReference, requestedManifestMIMETypes []string) (*dockerImageSource, error) {
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c, err := newDockerClient(ctx, ref, false, "pull")
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if err != nil {
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return nil, err
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}
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if requestedManifestMIMETypes == nil {
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requestedManifestMIMETypes = manifest.DefaultRequestedManifestMIMETypes
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}
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supportedMIMEs := supportedManifestMIMETypesMap()
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acceptableRequestedMIMEs := false
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for _, mtrequested := range requestedManifestMIMETypes {
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if supportedMIMEs[mtrequested] {
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acceptableRequestedMIMEs = true
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break
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}
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}
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if !acceptableRequestedMIMEs {
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requestedManifestMIMETypes = manifest.DefaultRequestedManifestMIMETypes
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}
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return &dockerImageSource{
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ref: ref,
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requestedManifestMIMETypes: requestedManifestMIMETypes,
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c: c,
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}, nil
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}
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// Reference returns the reference used to set up this source, _as specified by the user_
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// (not as the image itself, or its underlying storage, claims). This can be used e.g. to determine which public keys are trusted for this image.
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func (s *dockerImageSource) Reference() types.ImageReference {
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return s.ref
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}
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// Close removes resources associated with an initialized ImageSource, if any.
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func (s *dockerImageSource) Close() error {
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return nil
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}
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// simplifyContentType drops parameters from a HTTP media type (see https://tools.ietf.org/html/rfc7231#section-3.1.1.1)
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// Alternatively, an empty string is returned unchanged, and invalid values are "simplified" to an empty string.
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func simplifyContentType(contentType string) string {
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if contentType == "" {
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return contentType
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}
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mimeType, _, err := mime.ParseMediaType(contentType)
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if err != nil {
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return ""
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}
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return mimeType
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}
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// GetManifest returns the image's manifest along with its MIME type (which may be empty when it can't be determined but the manifest is available).
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// It may use a remote (= slow) service.
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func (s *dockerImageSource) GetManifest() ([]byte, string, error) {
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err := s.ensureManifestIsLoaded()
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if err != nil {
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return nil, "", err
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}
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return s.cachedManifest, s.cachedManifestMIMEType, nil
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}
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func (s *dockerImageSource) fetchManifest(tagOrDigest string) ([]byte, string, error) {
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url := fmt.Sprintf(manifestURL, reference.Path(s.ref.ref), tagOrDigest)
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headers := make(map[string][]string)
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headers["Accept"] = s.requestedManifestMIMETypes
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res, err := s.c.makeRequest("GET", url, headers, nil)
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if err != nil {
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return nil, "", err
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}
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defer res.Body.Close()
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if res.StatusCode != http.StatusOK {
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return nil, "", client.HandleErrorResponse(res)
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}
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manblob, err := ioutil.ReadAll(res.Body)
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if err != nil {
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return nil, "", err
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}
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return manblob, simplifyContentType(res.Header.Get("Content-Type")), nil
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}
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// GetTargetManifest returns an image's manifest given a digest.
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// This is mainly used to retrieve a single image's manifest out of a manifest list.
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func (s *dockerImageSource) GetTargetManifest(digest digest.Digest) ([]byte, string, error) {
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return s.fetchManifest(digest.String())
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}
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// ensureManifestIsLoaded sets s.cachedManifest and s.cachedManifestMIMEType
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//
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// ImageSource implementations are not required or expected to do any caching,
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// but because our signatures are “attached” to the manifest digest,
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// we need to ensure that the digest of the manifest returned by GetManifest
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// and used by GetSignatures are consistent, otherwise we would get spurious
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// signature verification failures when pulling while a tag is being updated.
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func (s *dockerImageSource) ensureManifestIsLoaded() error {
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if s.cachedManifest != nil {
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return nil
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}
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reference, err := s.ref.tagOrDigest()
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if err != nil {
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return err
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}
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manblob, mt, err := s.fetchManifest(reference)
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if err != nil {
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return err
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}
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// We might validate manblob against the Docker-Content-Digest header here to protect against transport errors.
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s.cachedManifest = manblob
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s.cachedManifestMIMEType = mt
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return nil
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}
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func (s *dockerImageSource) getExternalBlob(urls []string) (io.ReadCloser, int64, error) {
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var (
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resp *http.Response
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err error
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)
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for _, url := range urls {
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resp, err = s.c.makeRequestToResolvedURL("GET", url, nil, nil, -1, false)
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if err == nil {
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if resp.StatusCode != http.StatusOK {
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err = errors.Errorf("error fetching external blob from %q: %d", url, resp.StatusCode)
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logrus.Debug(err)
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continue
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}
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}
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}
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if resp.Body != nil && err == nil {
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return resp.Body, getBlobSize(resp), nil
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}
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return nil, 0, err
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}
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func getBlobSize(resp *http.Response) int64 {
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size, err := strconv.ParseInt(resp.Header.Get("Content-Length"), 10, 64)
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if err != nil {
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size = -1
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}
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return size
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}
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// GetBlob returns a stream for the specified blob, and the blob’s size (or -1 if unknown).
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func (s *dockerImageSource) GetBlob(info types.BlobInfo) (io.ReadCloser, int64, error) {
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if len(info.URLs) != 0 {
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return s.getExternalBlob(info.URLs)
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}
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url := fmt.Sprintf(blobsURL, reference.Path(s.ref.ref), info.Digest.String())
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logrus.Debugf("Downloading %s", url)
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res, err := s.c.makeRequest("GET", url, nil, nil)
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if err != nil {
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return nil, 0, err
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}
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if res.StatusCode != http.StatusOK {
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// print url also
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return nil, 0, errors.Errorf("Invalid status code returned when fetching blob %d", res.StatusCode)
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}
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return res.Body, getBlobSize(res), nil
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}
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func (s *dockerImageSource) GetSignatures() ([][]byte, error) {
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if s.c.signatureBase == nil { // Skip dealing with the manifest digest if not necessary.
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return [][]byte{}, nil
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}
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if err := s.ensureManifestIsLoaded(); err != nil {
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return nil, err
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}
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manifestDigest, err := manifest.Digest(s.cachedManifest)
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if err != nil {
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return nil, err
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}
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signatures := [][]byte{}
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for i := 0; ; i++ {
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url := signatureStorageURL(s.c.signatureBase, manifestDigest, i)
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if url == nil {
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return nil, errors.Errorf("Internal error: signatureStorageURL with non-nil base returned nil")
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}
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signature, missing, err := s.getOneSignature(url)
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if err != nil {
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return nil, err
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}
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if missing {
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break
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}
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signatures = append(signatures, signature)
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}
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return signatures, nil
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}
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// getOneSignature downloads one signature from url.
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// If it successfully determines that the signature does not exist, returns with missing set to true and error set to nil.
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func (s *dockerImageSource) getOneSignature(url *url.URL) (signature []byte, missing bool, err error) {
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switch url.Scheme {
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case "file":
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logrus.Debugf("Reading %s", url.Path)
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sig, err := ioutil.ReadFile(url.Path)
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if err != nil {
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if os.IsNotExist(err) {
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return nil, true, nil
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}
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return nil, false, err
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}
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return sig, false, nil
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case "http", "https":
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logrus.Debugf("GET %s", url)
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res, err := s.c.client.Get(url.String())
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if err != nil {
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return nil, false, err
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}
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defer res.Body.Close()
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if res.StatusCode == http.StatusNotFound {
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return nil, true, nil
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} else if res.StatusCode != http.StatusOK {
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return nil, false, errors.Errorf("Error reading signature from %s: status %d", url.String(), res.StatusCode)
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}
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sig, err := ioutil.ReadAll(res.Body)
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if err != nil {
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return nil, false, err
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}
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return sig, false, nil
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default:
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return nil, false, errors.Errorf("Unsupported scheme when reading signature from %s", url.String())
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}
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}
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// deleteImage deletes the named image from the registry, if supported.
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func deleteImage(ctx *types.SystemContext, ref dockerReference) error {
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c, err := newDockerClient(ctx, ref, true, "push")
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if err != nil {
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return err
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}
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// When retrieving the digest from a registry >= 2.3 use the following header:
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// "Accept": "application/vnd.docker.distribution.manifest.v2+json"
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headers := make(map[string][]string)
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headers["Accept"] = []string{manifest.DockerV2Schema2MediaType}
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refTail, err := ref.tagOrDigest()
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if err != nil {
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return err
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}
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getURL := fmt.Sprintf(manifestURL, reference.Path(ref.ref), refTail)
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get, err := c.makeRequest("GET", getURL, headers, nil)
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if err != nil {
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return err
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}
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defer get.Body.Close()
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manifestBody, err := ioutil.ReadAll(get.Body)
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if err != nil {
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return err
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}
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switch get.StatusCode {
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case http.StatusOK:
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case http.StatusNotFound:
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return errors.Errorf("Unable to delete %v. Image may not exist or is not stored with a v2 Schema in a v2 registry", ref.ref)
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default:
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return errors.Errorf("Failed to delete %v: %s (%v)", ref.ref, manifestBody, get.Status)
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}
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digest := get.Header.Get("Docker-Content-Digest")
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deleteURL := fmt.Sprintf(manifestURL, reference.Path(ref.ref), digest)
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// When retrieving the digest from a registry >= 2.3 use the following header:
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// "Accept": "application/vnd.docker.distribution.manifest.v2+json"
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delete, err := c.makeRequest("DELETE", deleteURL, headers, nil)
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if err != nil {
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return err
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}
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defer delete.Body.Close()
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body, err := ioutil.ReadAll(delete.Body)
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if err != nil {
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return err
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}
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if delete.StatusCode != http.StatusAccepted {
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return errors.Errorf("Failed to delete %v: %s (%v)", deleteURL, string(body), delete.Status)
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}
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if c.signatureBase != nil {
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manifestDigest, err := manifest.Digest(manifestBody)
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if err != nil {
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return err
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}
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for i := 0; ; i++ {
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url := signatureStorageURL(c.signatureBase, manifestDigest, i)
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if url == nil {
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return errors.Errorf("Internal error: signatureStorageURL with non-nil base returned nil")
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}
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missing, err := c.deleteOneSignature(url)
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if err != nil {
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return err
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}
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if missing {
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break
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}
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}
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}
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return nil
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}
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