drone/registry/types/digest.go

128 lines
3.2 KiB
Go

// Copyright 2023 Harness, Inc.
//
// 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 types
import (
"errors"
"fmt"
"github.com/harness/gitness/registry/app/store/database/util"
"github.com/opencontainers/go-digest"
)
// Digest is the database representation of a digest, stored in the format `<algorithm prefix><hex>`.
type Digest string
const (
// Algorithm prefixes are sequences of two digits. These should never change, only additions are allowed.
sha256DigestAlgorithmPrefix = "01"
sha512DigestAlgorithmPrefix = "02"
)
func GetDigestBytes(dgst digest.Digest) ([]byte, error) {
if len(dgst.String()) == 0 {
return nil, nil
}
newDigest, err := NewDigest(dgst)
if err != nil {
return nil, err
}
digestBytes, err := util.GetHexDecodedBytes(string(newDigest))
if err != nil {
return nil, err
}
return digestBytes, nil
}
// String implements the Stringer interface.
func (d Digest) String() string {
return string(d)
}
// NewDigest builds a Digest based on a digest.Digest.
func NewDigest(d digest.Digest) (Digest, error) {
if err := d.Validate(); err != nil {
return "", err
}
var algPrefix string
switch d.Algorithm() {
case digest.SHA256:
algPrefix = sha256DigestAlgorithmPrefix
case digest.SHA512:
algPrefix = sha512DigestAlgorithmPrefix
case digest.SHA384:
return "", fmt.Errorf("unimplemented algorithm %q", digest.SHA384)
default:
return "", fmt.Errorf("unknown algorithm %q", d.Algorithm())
}
return Digest(fmt.Sprintf("%s%s", algPrefix, d.Hex())), nil
}
// Parse maps a Digest to a digest.Digest.
func (d Digest) Parse() (digest.Digest, error) {
str := d.String()
valid, err := d.validate(str)
if !valid {
return "", err
}
algPrefix := str[:2]
if len(str) == 2 {
return "", errors.New("no checksum")
}
var alg digest.Algorithm
switch algPrefix {
case sha256DigestAlgorithmPrefix:
alg = digest.SHA256
case sha512DigestAlgorithmPrefix:
alg = digest.SHA512
default:
return "", fmt.Errorf("unknown algorithm prefix %q", algPrefix)
}
dgst := digest.NewDigestFromHex(alg.String(), str[2:])
if err := dgst.Validate(); err != nil {
return "", err
}
return dgst, nil
}
func (d Digest) validate(str string) (bool, error) {
if len(str) == 0 {
return false, nil
}
if len(str) < 2 {
return false, errors.New("invalid digest length")
}
return true, nil
}
// HexDecode decodes binary data from a textual representation.
// The output is equivalent to the PostgreSQL binary `decode` function with the hex textual format. See
// https://www.postgresql.org/docs/14/functions-binarystring.html.
func (d Digest) HexDecode() string {
return fmt.Sprintf("\\x%s", d.String())
}
func (d Digest) Validate() string {
return fmt.Sprintf("\\x%s", d.String())
}