frostfs-api-go/hash/hash.go

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2019-11-18 13:34:06 +00:00
package hash
import (
"bytes"
"github.com/mr-tron/base58"
"github.com/nspcc-dev/neofs-proto/internal"
"github.com/nspcc-dev/tzhash/tz"
"github.com/pkg/errors"
)
// HomomorphicHashSize contains size of HH.
const HomomorphicHashSize = 64
// Hash is implementation of HomomorphicHash.
type Hash [HomomorphicHashSize]byte
// ErrWrongDataSize raised when wrong size of bytes is passed to unmarshal HH.
const ErrWrongDataSize = internal.Error("wrong data size")
var (
_ internal.Custom = (*Hash)(nil)
emptyHH [HomomorphicHashSize]byte
)
// Size returns size of Hash (HomomorphicHashSize).
func (h Hash) Size() int { return HomomorphicHashSize }
// Empty checks that Hash is empty.
func (h Hash) Empty() bool { return bytes.Equal(h.Bytes(), emptyHH[:]) }
// Reset sets current Hash to empty value.
func (h *Hash) Reset() { *h = Hash{} }
// ProtoMessage method to satisfy proto.Message interface.
func (h Hash) ProtoMessage() {}
// Bytes represents Hash as bytes.
func (h Hash) Bytes() []byte {
buf := make([]byte, HomomorphicHashSize)
copy(buf, h[:])
return h[:]
}
// Marshal returns bytes representation of Hash.
func (h Hash) Marshal() ([]byte, error) { return h.Bytes(), nil }
// MarshalTo tries to marshal Hash into passed bytes and returns count of copied bytes.
func (h *Hash) MarshalTo(data []byte) (int, error) { return copy(data, h.Bytes()), nil }
// Unmarshal tries to parse bytes into valid Hash.
func (h *Hash) Unmarshal(data []byte) error {
if ln := len(data); ln != HomomorphicHashSize {
return errors.Wrapf(ErrWrongDataSize, "expect=%d, actual=%d", HomomorphicHashSize, ln)
}
copy((*h)[:], data)
return nil
}
// String returns string representation of Hash.
func (h Hash) String() string { return base58.Encode(h[:]) }
// Equal checks that current Hash is equal to passed Hash.
func (h Hash) Equal(hash Hash) bool { return h == hash }
// Verify validates if current hash generated from passed data.
func (h Hash) Verify(data []byte) bool { return h.Equal(Sum(data)) }
// Validate checks if combined hashes are equal to current Hash.
func (h Hash) Validate(hashes []Hash) bool {
var hashBytes = make([][]byte, 0, len(hashes))
for i := range hashes {
hashBytes = append(hashBytes, hashes[i].Bytes())
}
ok, err := tz.Validate(h.Bytes(), hashBytes)
return err == nil && ok
}
// Sum returns Tillich-Zémor checksum of data.
func Sum(data []byte) Hash { return tz.Sum(data) }
// Concat combines hashes based on homomorphic property.
func Concat(hashes []Hash) (Hash, error) {
var (
hash Hash
h = make([][]byte, 0, len(hashes))
)
for i := range hashes {
h = append(h, hashes[i].Bytes())
}
cat, err := tz.Concat(h)
if err != nil {
return hash, err
}
return hash, hash.Unmarshal(cat)
}