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|
package md5crypt
import (
"fmt"
"strconv"
"strings"
"github.com/go-crypt/crypt/algorithm"
"github.com/go-crypt/crypt/internal/encoding"
)
// RegisterDecoder the decoder with the algorithm.DecoderRegister.
func RegisterDecoder(r algorithm.DecoderRegister) (err error) {
if err = RegisterDecoderCommon(r); err != nil {
return err
}
if err = RegisterDecoderSun(r); err != nil {
return err
}
return nil
}
// RegisterDecoderCommon registers specifically the common decoder variant with the algorithm.DecoderRegister.
func RegisterDecoderCommon(r algorithm.DecoderRegister) (err error) {
if err = r.RegisterDecodeFunc(VariantStandard.Prefix(), DecodeVariant(VariantStandard)); err != nil {
return err
}
return nil
}
// RegisterDecoderSun registers specifically the sun decoder variant with the algorithm.DecoderRegister.
func RegisterDecoderSun(r algorithm.DecoderRegister) (err error) {
if err = r.RegisterDecodeFunc(VariantSun.Prefix(), DecodeVariant(VariantSun)); err != nil {
return err
}
if err = r.RegisterDecodePrefix("$md5,", VariantSun.Prefix()); err != nil {
return err
}
return nil
}
// Decode the encoded digest into a algorithm.Digest.
func Decode(encodedDigest string) (digest algorithm.Digest, err error) {
return DecodeVariant(VariantNone)(encodedDigest)
}
// DecodeVariant the encoded digest into a algorithm.Digest provided it matches the provided Variant. If VariantNone is
// used all variants can be decoded.
func DecodeVariant(v Variant) func(encodedDigest string) (digest algorithm.Digest, err error) {
return func(encodedDigest string) (digest algorithm.Digest, err error) {
var (
parts []string
variant Variant
)
if variant, parts, err = decoderParts(encodedDigest); err != nil {
return nil, fmt.Errorf(algorithm.ErrFmtDigestDecode, AlgName, err)
}
if v != VariantNone && v != variant {
return nil, fmt.Errorf(algorithm.ErrFmtDigestDecode, AlgName, fmt.Errorf("the '%s' variant cannot be decoded only the '%s' variant can be", variant.String(), v.String()))
}
if digest, err = decode(variant, parts); err != nil {
return nil, fmt.Errorf(algorithm.ErrFmtDigestDecode, AlgName, err)
}
return digest, nil
}
}
func decoderParts(encodedDigest string) (variant Variant, parts []string, err error) {
partsTemp := encoding.Split(encodedDigest, -1)
p := len(partsTemp)
if p != 4 && p != 5 {
return VariantNone, nil, algorithm.ErrEncodedHashInvalidFormat
}
switch partsTemp[1] {
case AlgIdentifier:
if p != 4 {
return VariantNone, nil, algorithm.ErrEncodedHashInvalidFormat
}
default:
if p != 5 {
return VariantNone, nil, algorithm.ErrEncodedHashInvalidFormat
}
}
if strings.HasPrefix(partsTemp[1], "md5,") {
parts = append([]string{strings.SplitN(partsTemp[1], ",", 2)[1]}, partsTemp[2:]...)
variant = VariantSun
} else {
switch variant = NewVariant(partsTemp[1]); variant {
case VariantNone:
return variant, nil, fmt.Errorf("%w: identifier '%s' is not an encoded %s digest", algorithm.ErrEncodedHashInvalidIdentifier, partsTemp[1], AlgName)
default:
parts = append([]string{""}, partsTemp[2:]...)
}
}
return variant, parts, nil
}
func decode(variant Variant, parts []string) (digest algorithm.Digest, err error) {
decoded := &Digest{
variant: variant,
}
var params []encoding.Parameter
if parts[0] != "" {
if variant != VariantSun {
return nil, fmt.Errorf("%w: parameters are only valid for the %s variant but the %s variant was decoded", algorithm.ErrParameterInvalid, VariantSun.String(), variant.String())
}
if params, err = encoding.DecodeParameterStr(parts[0]); err != nil {
return nil, err
}
for _, param := range params {
switch param.Key {
case "rounds":
var value uint64
if value, err = strconv.ParseUint(param.Value, 10, 32); err != nil {
return nil, fmt.Errorf("%w: option '%s' has invalid value '%s': %v", algorithm.ErrEncodedHashInvalidOptionValue, param.Key, param.Value, err)
}
decoded.iterations = uint32(value)
default:
return nil, fmt.Errorf("%w: option '%s' with value '%s' is unknown", algorithm.ErrEncodedHashInvalidOptionKey, param.Key, param.Value)
}
}
}
switch variant {
case VariantSun:
decoded.salt, decoded.key = []byte(parts[1]), []byte(parts[3])
default:
decoded.salt, decoded.key = []byte(parts[1]), []byte(parts[2])
}
return decoded, nil
}
|
