distribution/manifest/manifest.go
Stephen J Day 14fb80d6c3 Add payload and signatures method to SignedManifest
To provide easier access to digestible content, the paylaod has been made
accessible on the signed manifest type. This hides the specifics of the
interaction with libtrust with the caveat that signatures may be parsed twice.

We'll have to have a future look at the interface for manifest as we may be
making problematic architectural decisions. We'll visit this after the initial
release.

Signed-off-by: Stephen J Day <stephen.day@docker.com>
2015-02-03 13:30:20 -08:00

114 lines
3.4 KiB
Go

package manifest
import (
"encoding/json"
"github.com/docker/distribution/digest"
"github.com/docker/libtrust"
)
// Versioned provides a struct with just the manifest schemaVersion. Incoming
// content with unknown schema version can be decoded against this struct to
// check the version.
type Versioned struct {
// SchemaVersion is the image manifest schema that this image follows
SchemaVersion int `json:"schemaVersion"`
}
// Manifest provides the base accessible fields for working with V2 image
// format in the registry.
type Manifest struct {
Versioned
// Name is the name of the image's repository
Name string `json:"name"`
// Tag is the tag of the image specified by this manifest
Tag string `json:"tag"`
// Architecture is the host architecture on which this image is intended to
// run
Architecture string `json:"architecture"`
// FSLayers is a list of filesystem layer blobSums contained in this image
FSLayers []FSLayer `json:"fsLayers"`
// History is a list of unstructured historical data for v1 compatibility
History []History `json:"history"`
}
// SignedManifest provides an envelope for a signed image manifest, including
// the format sensitive raw bytes. It contains fields to
type SignedManifest struct {
Manifest
// Raw is the byte representation of the ImageManifest, used for signature
// verification. The value of Raw must be used directly during
// serialization, or the signature check will fail. The manifest byte
// representation cannot change or it will have to be re-signed.
Raw []byte `json:"-"`
}
// UnmarshalJSON populates a new ImageManifest struct from JSON data.
func (sm *SignedManifest) UnmarshalJSON(b []byte) error {
var manifest Manifest
if err := json.Unmarshal(b, &manifest); err != nil {
return err
}
sm.Manifest = manifest
sm.Raw = make([]byte, len(b), len(b))
copy(sm.Raw, b)
return nil
}
// Payload returns the raw, signed content of the signed manifest. The
// contents can be used to calculate the content identifier.
func (sm *SignedManifest) Payload() ([]byte, error) {
jsig, err := libtrust.ParsePrettySignature(sm.Raw, "signatures")
if err != nil {
return nil, err
}
// Resolve the payload in the manifest.
return jsig.Payload()
}
// Signatures returns the signatures as provided by
// (*libtrust.JSONSignature).Signatures. The byte slices are opaque jws
// signatures.
func (sm *SignedManifest) Signatures() ([][]byte, error) {
jsig, err := libtrust.ParsePrettySignature(sm.Raw, "signatures")
if err != nil {
return nil, err
}
// Resolve the payload in the manifest.
return jsig.Signatures()
}
// MarshalJSON returns the contents of raw. If Raw is nil, marshals the inner
// contents. Applications requiring a marshaled signed manifest should simply
// use Raw directly, since the the content produced by json.Marshal will be
// compacted and will fail signature checks.
func (sm *SignedManifest) MarshalJSON() ([]byte, error) {
if len(sm.Raw) > 0 {
return sm.Raw, nil
}
// If the raw data is not available, just dump the inner content.
return json.Marshal(&sm.Manifest)
}
// FSLayer is a container struct for BlobSums defined in an image manifest
type FSLayer struct {
// BlobSum is the tarsum of the referenced filesystem image layer
BlobSum digest.Digest `json:"blobSum"`
}
// History stores unstructured v1 compatibility information
type History struct {
// V1Compatibility is the raw v1 compatibility information
V1Compatibility string `json:"v1Compatibility"`
}