docs/tuf/data/snapshot.go

105 lines
2.5 KiB
Go

package data
import (
"bytes"
"time"
"github.com/Sirupsen/logrus"
"github.com/jfrazelle/go/canonical/json"
)
// SignedSnapshot is a fully unpacked snapshot.json
type SignedSnapshot struct {
Signatures []Signature
Signed Snapshot
Dirty bool
}
// Snapshot is the Signed component of a snapshot.json
type Snapshot struct {
Type string `json:"_type"`
Version int `json:"version"`
Expires time.Time `json:"expires"`
Meta Files `json:"meta"`
}
// NewSnapshot initilizes a SignedSnapshot with a given top level root
// and targets objects
func NewSnapshot(root *Signed, targets *Signed) (*SignedSnapshot, error) {
logrus.Debug("generating new snapshot...")
targetsJSON, err := json.Marshal(targets)
if err != nil {
logrus.Debug("Error Marshalling Targets")
return nil, err
}
rootJSON, err := json.Marshal(root)
if err != nil {
logrus.Debug("Error Marshalling Root")
return nil, err
}
rootMeta, err := NewFileMeta(bytes.NewReader(rootJSON), "sha256")
if err != nil {
return nil, err
}
targetsMeta, err := NewFileMeta(bytes.NewReader(targetsJSON), "sha256")
if err != nil {
return nil, err
}
return &SignedSnapshot{
Signatures: make([]Signature, 0),
Signed: Snapshot{
Type: TUFTypes["snapshot"],
Version: 0,
Expires: DefaultExpires("snapshot"),
Meta: Files{
ValidRoles["root"]: rootMeta,
ValidRoles["targets"]: targetsMeta,
},
},
}, nil
}
func (sp *SignedSnapshot) hashForRole(role string) []byte {
return sp.Signed.Meta[role].Hashes["sha256"]
}
// ToSigned partially serializes a SignedSnapshot for further signing
func (sp SignedSnapshot) ToSigned() (*Signed, error) {
s, err := json.MarshalCanonical(sp.Signed)
if err != nil {
return nil, err
}
signed := json.RawMessage{}
err = signed.UnmarshalJSON(s)
if err != nil {
return nil, err
}
sigs := make([]Signature, len(sp.Signatures))
copy(sigs, sp.Signatures)
return &Signed{
Signatures: sigs,
Signed: signed,
}, nil
}
// AddMeta updates a role in the snapshot with new meta
func (sp *SignedSnapshot) AddMeta(role string, meta FileMeta) {
sp.Signed.Meta[role] = meta
sp.Dirty = true
}
// SnapshotFromSigned fully unpacks a Signed object into a SignedSnapshot
func SnapshotFromSigned(s *Signed) (*SignedSnapshot, error) {
sp := Snapshot{}
err := json.Unmarshal(s.Signed, &sp)
if err != nil {
return nil, err
}
sigs := make([]Signature, len(s.Signatures))
copy(sigs, s.Signatures)
return &SignedSnapshot{
Signatures: sigs,
Signed: sp,
}, nil
}