github.com/cyverse/go-irodsclient@v0.13.2/irods/types/data_object_checksum.go

package types

import (
	"encoding/base64"
	"encoding/hex"
	"fmt"
	"strings"

	"golang.org/x/xerrors"
)

// ChecksumAlgorithm determines checksum algorithm
type ChecksumAlgorithm string

const (
	// ChecksumAlgorithmSHA1 is for SHA1
	ChecksumAlgorithmSHA1 ChecksumAlgorithm = "SHA-1"
	// ChecksumAlgorithmSHA256 is for SHA256
	ChecksumAlgorithmSHA256 ChecksumAlgorithm = "SHA-256"
	// ChecksumAlgorithmSHA512 is for SHA512
	ChecksumAlgorithmSHA512 ChecksumAlgorithm = "SHA-512"
	// ChecksumAlgorithmADLER32 is for ADLER32
	ChecksumAlgorithmADLER32 ChecksumAlgorithm = "ADLER-32"
	// ChecksumAlgorithmMD5 is for MD5
	ChecksumAlgorithmMD5 ChecksumAlgorithm = "MD5"
	// ChecksumAlgorithmUnknown is for unknown algorithm
	ChecksumAlgorithmUnknown ChecksumAlgorithm = ""
)

// IRODSChecksum contains data object hash information
type IRODSChecksum struct {
	OriginalChecksum string
	Algorithm        ChecksumAlgorithm
	Checksum         []byte
}

// CreateIRODSChecksum creates IRODSChecksum from checksum string
func CreateIRODSChecksum(checksumString string) (*IRODSChecksum, error) {
	if len(checksumString) == 0 {
		// completely normal
		return &IRODSChecksum{
			OriginalChecksum: "",
			Algorithm:        "",
			Checksum:         nil,
		}, nil
	}

	algorithm, checksum, err := ParseIRODSChecksum(checksumString)
	if err != nil {
		return nil, xerrors.Errorf("failed to split data object checksum: %w", err)
	}

	return &IRODSChecksum{
		OriginalChecksum: checksumString,
		Algorithm:        algorithm,
		Checksum:         checksum,
	}, nil
}

// ToString stringifies the object
func (checksum *IRODSChecksum) ToString() string {
	return fmt.Sprintf("<IRODSChecksum %s %x>", checksum.Algorithm, checksum.Checksum)
}

// GetChecksumString returns checksum in string
func (checksum *IRODSChecksum) GetChecksumString() string {
	return hex.EncodeToString(checksum.Checksum)
}

// GetOriginalChecksum returns original checksum in string
func (checksum *IRODSChecksum) GetOriginalChecksum() string {
	return checksum.OriginalChecksum
}

// GetHashAlgorithm returns checksum algorithm
func (checksum *IRODSChecksum) GetChecksumAlgorithm() string {
	return string(checksum.Algorithm)
}

// ParseIRODSChecksum parses iRODS checksum string
func ParseIRODSChecksum(checksumString string) (ChecksumAlgorithm, []byte, error) {
	sp := strings.Split(checksumString, ":")

	if len(sp) == 0 || len(sp) > 2 {
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unexpected checksum: %v", string(checksumString))
	}

	algorithm := ""
	checksum := ""

	if len(sp) == 1 {
		algorithm = string(ChecksumAlgorithmMD5)
		checksum = checksumString
	} else if len(sp) >= 2 {
		algorithm = sp[0]
		checksum = sp[1]
	}

	switch strings.ToLower(algorithm) {
	case "sha2":
		checksumBase64, err := base64.StdEncoding.DecodeString(checksum)
		if err != nil {
			return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("failed to base64 decode checksum: %v", err)
		}

		if len(checksumBase64) == 256/8 {
			return ChecksumAlgorithmSHA256, checksumBase64, nil
		} else if len(checksumBase64) == 512/8 {
			return ChecksumAlgorithmSHA512, checksumBase64, nil
		}
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unknown checksum algorithm: %s len %d", algorithm, len(checksumBase64))
	case "sha256", strings.ToLower(string(ChecksumAlgorithmSHA256)):
		checksumBase64, err := base64.StdEncoding.DecodeString(checksum)
		if err != nil {
			return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("failed to base64 decode checksum: %v", err)
		}

		if len(checksumBase64) == 256/8 {
			return ChecksumAlgorithmSHA256, checksumBase64, nil
		}
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unknown checksum algorithm: %s len %d", algorithm, len(checksumBase64))
	case "sha512", strings.ToLower(string(ChecksumAlgorithmSHA512)):
		checksumBase64, err := base64.StdEncoding.DecodeString(checksum)
		if err != nil {
			return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("failed to base64 decode checksum: %v", err)
		}

		if len(checksumBase64) == 512/8 {
			return ChecksumAlgorithmSHA512, checksumBase64, nil
		}
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unknown checksum algorithm: %s len %d", algorithm, len(checksumBase64))
	case "sha1", strings.ToLower(string(ChecksumAlgorithmSHA1)):
		checksumBase64, err := base64.StdEncoding.DecodeString(checksum)
		if err != nil {
			return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("failed to base64 decode checksum: %v", err)
		}

		if len(checksumBase64) == 160/8 {
			return ChecksumAlgorithmSHA1, checksumBase64, nil
		}
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unknown checksum algorithm: %s len %d", algorithm, len(checksumBase64))
	case "adler32", strings.ToLower(string(ChecksumAlgorithmADLER32)):
		checksumHex, err := hex.DecodeString(checksum)
		if err != nil {
			return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("failed to hex decode checksum: %v", err)
		}

		if len(checksumHex) == 32/8 {
			return ChecksumAlgorithmADLER32, checksumHex, nil
		}
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unknown checksum algorithm: %s len %d", algorithm, len(checksumHex))
	case strings.ToLower(string(ChecksumAlgorithmMD5)):
		checksumHex, err := hex.DecodeString(checksum)
		if err != nil {
			return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("failed to hex decode checksum: %v", err)
		}

		if len(checksumHex) == 128/8 {
			return ChecksumAlgorithmMD5, checksumHex, nil
		}
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unknown checksum algorithm: %s len %d", algorithm, len(checksumHex))
	default:
		return ChecksumAlgorithmUnknown, nil, xerrors.Errorf("unknown checksum algorithm: %s", algorithm)
	}
}