working commit

pkg/repocli/digest.go

@@ -3,7 +3,10 @@ package repocli
 import (
 	"crypto/sha256"
 	"crypto/sha512"
+	"hash"
+
 	"encoding/hex"
+	"errors"
 	"strings"
 )
 
@@ -21,15 +24,17 @@ func SHA512Digest(src []byte) string {
 	return "sha512:" + hex.EncodeToString(sum)
 }
 
+type Algorithm int
+
 const (
-	Undefined int = iota
+	Undefined Algorithm = iota
 	SHA256
 	SHA512
 )
 
-func DigestType(digest string) int {
+func DigestType(digest string) Algorithm {
 	var err error
-	var typ int
+	var typ Algorithm
 	digest = strings.ToLower(digest)
 	digest = strings.TrimPrefix(digest, "sha256:")
 	digest = strings.TrimPrefix(digest, "sha512:")
@@ -47,3 +52,83 @@ func DigestType(digest string) int {
 	}
 	return typ
 }
+
+type Digest struct {
+	algorithm Algorithm
+	decoded   []byte
+}
+
+func NewDigestFromBytes(algorithm Algorithm, payload []byte) *Digest {
+	var sum []byte
+	var hasher hash.Hash
+	switch algorithm {
+	case SHA512:
+		hasher = sha512.New()
+	default:
+		hasher = sha256.New()
+	}
+	hasher.Write(payload)
+	sum = hasher.Sum(nil)
+	digest := &Digest{
+		algorithm: algorithm,
+		decoded:   sum,
+	}
+	return digest
+}
+
+func ParseDigest(str string) (*Digest, error) {
+	var err error
+	digest := &Digest{}
+
+	str = strings.ToLower(str)
+	str = strings.TrimPrefix(str, "sha256:")
+	str = strings.TrimPrefix(str, "sha512:")
+
+	decoded, err := hex.DecodeString(str)
+	if err != nil {
+		err := errors.New("Can't decode digest")
+		return digest, err
+	}
+	digest.decoded = decoded
+	switch len(decoded) {
+	case 32:
+		digest.algorithm = SHA256
+	case 64:
+		digest.algorithm = SHA512
+	default:
+		err = errors.New("Unknown digest type")
+		return digest, err
+	}
+	return digest, err
+}
+
+func (dig *Digest) Hex() string {
+	return hex.EncodeToString(dig.decoded)
+}
+
+func (dig *Digest) Algorithm() Algorithm {
+	return dig.algorithm
+}
+
+func (dig *Digest) Prefix() string {
+	var prefix string
+	switch dig.algorithm {
+	case SHA256:
+		prefix = "sha256"
+	case SHA512:
+		prefix = "sha512"
+	}
+	return prefix
+}
+
+func (dig *Digest) Encoded() string {
+	var prefix string
+	switch dig.algorithm {
+	case SHA256:
+		prefix = "sha256"
+	case SHA512:
+		prefix = "sha512"
+	}
+	hexx := hex.EncodeToString(dig.decoded)
+	return prefix + ":" + hexx
+}