frostfs-sdk-go/checksum/checksum.go

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package checksum
import (
"crypto/sha256"
"encoding/hex"
"errors"
"fmt"
"github.com/nspcc-dev/neofs-api-go/v2/refs"
"github.com/nspcc-dev/tzhash/tz"
)
// Checksum represents checksum of some digital data.
//
// Checksum is mutually compatible with github.com/nspcc-dev/neofs-api-go/v2/refs.Checksum
// message. See ReadFromV2 / WriteToV2 methods.
//
// Instances can be created using built-in var declaration.
//
// Note that direct typecast is not safe and may result in loss of compatibility:
// _ = Checksum(refs.Checksum{}) // not recommended
type Checksum refs.Checksum
// Type represents the enumeration
// of checksum types.
type Type uint8
const (
// Unknown is an undefined checksum type.
Unknown Type = iota
// SHA256 is a SHA256 checksum type.
SHA256
// TZ is a Tillich-Zémor checksum type.
TZ
)
// ReadFromV2 reads Checksum from the refs.Checksum message. Checks if the
// message conforms to NeoFS API V2 protocol.
//
// See also WriteToV2.
func (c *Checksum) ReadFromV2(m refs.Checksum) error {
if len(m.GetSum()) == 0 {
return errors.New("missing value")
}
switch m.GetType() {
default:
return fmt.Errorf("unsupported type %v", m.GetType())
case refs.SHA256, refs.TillichZemor:
}
*c = Checksum(m)
return nil
}
// WriteToV2 writes Checksum to the refs.Checksum message.
// The message must not be nil.
//
// See also ReadFromV2.
func (c Checksum) WriteToV2(m *refs.Checksum) {
*m = (refs.Checksum)(c)
}
// Type returns checksum type.
//
// Zero Checksum has Unknown checksum type.
//
// See also SetTillichZemor and SetSHA256.
func (c Checksum) Type() Type {
v2 := (refs.Checksum)(c)
switch v2.GetType() {
case refs.SHA256:
return SHA256
case refs.TillichZemor:
return TZ
default:
return Unknown
}
}
// Value returns checksum bytes. Return value
// MUST NOT be mutated.
//
// Zero Checksum has nil sum.
//
// See also SetTillichZemor and SetSHA256.
func (c Checksum) Value() []byte {
v2 := (refs.Checksum)(c)
return v2.GetSum()
}
// SetSHA256 sets checksum to SHA256 hash.
//
// See also Calculate.
func (c *Checksum) SetSHA256(v [sha256.Size]byte) {
v2 := (*refs.Checksum)(c)
v2.SetType(refs.SHA256)
v2.SetSum(v[:])
}
// Calculate calculates checksum and sets it
// to the passed checksum. Checksum must not be nil.
//
// Does nothing if the passed type is not one of the:
// * SHA256;
// * TZ.
//
// Does not mutate the passed value.
//
// See also SetSHA256, SetTillichZemor.
func Calculate(c *Checksum, t Type, v []byte) {
switch t {
case SHA256:
c.SetSHA256(sha256.Sum256(v))
case TZ:
c.SetTillichZemor(tz.Sum(v))
default:
}
}
// SetTillichZemor sets checksum to Tillich-Zémor hash.
//
// See also Calculate.
func (c *Checksum) SetTillichZemor(v [tz.Size]byte) {
v2 := (*refs.Checksum)(c)
v2.SetType(refs.TillichZemor)
v2.SetSum(v[:])
}
// String implements fmt.Stringer.
//
// String is designed to be human-readable, and its format MAY differ between
// SDK versions.
func (c Checksum) String() string {
v2 := (refs.Checksum)(c)
return fmt.Sprintf("%s:%s", c.Type(), hex.EncodeToString(v2.GetSum()))
}
// String implements fmt.Stringer.
//
// String is designed to be human-readable, and its format MAY differ between
// SDK versions.
func (m Type) String() string {
var m2 refs.ChecksumType
switch m {
default:
m2 = refs.UnknownChecksum
case TZ:
m2 = refs.TillichZemor
case SHA256:
m2 = refs.SHA256
}
return m2.String()
}