status-go/vendor/github.com/multiformats/go-multihash/multihash.go

299 lines
6.7 KiB
Go

// Package multihash is the Go implementation of
// https://github.com/multiformats/multihash, or self-describing
// hashes.
package multihash
import (
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
"math"
b58 "github.com/mr-tron/base58/base58"
)
// errors
var (
ErrUnknownCode = errors.New("unknown multihash code")
ErrTooShort = errors.New("multihash too short. must be >= 2 bytes")
ErrTooLong = errors.New("multihash too long. must be < 129 bytes")
ErrLenNotSupported = errors.New("multihash does not yet support digests longer than 127 bytes")
ErrInvalidMultihash = errors.New("input isn't valid multihash")
ErrVarintBufferShort = errors.New("uvarint: buffer too small")
ErrVarintTooLong = errors.New("uvarint: varint too big (max 64bit)")
)
// ErrInconsistentLen is returned when a decoded multihash has an inconsistent length
type ErrInconsistentLen struct {
dm *DecodedMultihash
}
func (e ErrInconsistentLen) Error() string {
return fmt.Sprintf("multihash length inconsistent: %v", e.dm)
}
// constants
const (
ID = 0x00
SHA1 = 0x11
SHA2_256 = 0x12
SHA2_512 = 0x13
SHA3_224 = 0x17
SHA3_256 = 0x16
SHA3_384 = 0x15
SHA3_512 = 0x14
SHA3 = SHA3_512
KECCAK_224 = 0x1A
KECCAK_256 = 0x1B
KECCAK_384 = 0x1C
KECCAK_512 = 0x1D
SHAKE_128 = 0x18
SHAKE_256 = 0x19
BLAKE2B_MIN = 0xb201
BLAKE2B_MAX = 0xb240
BLAKE2S_MIN = 0xb241
BLAKE2S_MAX = 0xb260
MD5 = 0xd5
DBL_SHA2_256 = 0x56
MURMUR3 = 0x22
X11 = 0x1100
)
func init() {
// Add blake2b (64 codes)
for c := uint64(BLAKE2B_MIN); c <= BLAKE2B_MAX; c++ {
n := c - BLAKE2B_MIN + 1
name := fmt.Sprintf("blake2b-%d", n*8)
Names[name] = c
Codes[c] = name
DefaultLengths[c] = int(n)
}
// Add blake2s (32 codes)
for c := uint64(BLAKE2S_MIN); c <= BLAKE2S_MAX; c++ {
n := c - BLAKE2S_MIN + 1
name := fmt.Sprintf("blake2s-%d", n*8)
Names[name] = c
Codes[c] = name
DefaultLengths[c] = int(n)
}
}
// Names maps the name of a hash to the code
var Names = map[string]uint64{
"id": ID,
"sha1": SHA1,
"sha2-256": SHA2_256,
"sha2-512": SHA2_512,
"sha3": SHA3_512,
"sha3-224": SHA3_224,
"sha3-256": SHA3_256,
"sha3-384": SHA3_384,
"sha3-512": SHA3_512,
"dbl-sha2-256": DBL_SHA2_256,
"murmur3": MURMUR3,
"keccak-224": KECCAK_224,
"keccak-256": KECCAK_256,
"keccak-384": KECCAK_384,
"keccak-512": KECCAK_512,
"shake-128": SHAKE_128,
"shake-256": SHAKE_256,
"x11": X11,
"md5": MD5,
}
// Codes maps a hash code to it's name
var Codes = map[uint64]string{
ID: "id",
SHA1: "sha1",
SHA2_256: "sha2-256",
SHA2_512: "sha2-512",
SHA3_224: "sha3-224",
SHA3_256: "sha3-256",
SHA3_384: "sha3-384",
SHA3_512: "sha3-512",
DBL_SHA2_256: "dbl-sha2-256",
MURMUR3: "murmur3",
KECCAK_224: "keccak-224",
KECCAK_256: "keccak-256",
KECCAK_384: "keccak-384",
KECCAK_512: "keccak-512",
SHAKE_128: "shake-128",
SHAKE_256: "shake-256",
X11: "x11",
MD5: "md5",
}
// DefaultLengths maps a hash code to it's default length
var DefaultLengths = map[uint64]int{
ID: -1,
SHA1: 20,
SHA2_256: 32,
SHA2_512: 64,
SHA3_224: 28,
SHA3_256: 32,
SHA3_384: 48,
SHA3_512: 64,
DBL_SHA2_256: 32,
KECCAK_224: 28,
KECCAK_256: 32,
MURMUR3: 4,
KECCAK_384: 48,
KECCAK_512: 64,
SHAKE_128: 32,
SHAKE_256: 64,
X11: 64,
MD5: 16,
}
func uvarint(buf []byte) (uint64, []byte, error) {
n, c := binary.Uvarint(buf)
if c == 0 {
return n, buf, ErrVarintBufferShort
} else if c < 0 {
return n, buf[-c:], ErrVarintTooLong
} else {
return n, buf[c:], nil
}
}
// DecodedMultihash represents a parsed multihash and allows
// easy access to the different parts of a multihash.
type DecodedMultihash struct {
Code uint64
Name string
Length int // Length is just int as it is type of len() opearator
Digest []byte // Digest holds the raw multihash bytes
}
// Multihash is byte slice with the following form:
// <hash function code><digest size><hash function output>.
// See the spec for more information.
type Multihash []byte
// HexString returns the hex-encoded representation of a multihash.
func (m *Multihash) HexString() string {
return hex.EncodeToString([]byte(*m))
}
// String is an alias to HexString().
func (m *Multihash) String() string {
return m.HexString()
}
// FromHexString parses a hex-encoded multihash.
func FromHexString(s string) (Multihash, error) {
b, err := hex.DecodeString(s)
if err != nil {
return Multihash{}, err
}
return Cast(b)
}
// B58String returns the B58-encoded representation of a multihash.
func (m Multihash) B58String() string {
return b58.Encode([]byte(m))
}
// FromB58String parses a B58-encoded multihash.
func FromB58String(s string) (m Multihash, err error) {
b, err := b58.Decode(s)
if err != nil {
return Multihash{}, ErrInvalidMultihash
}
return Cast(b)
}
// Cast casts a buffer onto a multihash, and returns an error
// if it does not work.
func Cast(buf []byte) (Multihash, error) {
dm, err := Decode(buf)
if err != nil {
return Multihash{}, err
}
if !ValidCode(dm.Code) {
return Multihash{}, ErrUnknownCode
}
return Multihash(buf), nil
}
// Decode parses multihash bytes into a DecodedMultihash.
func Decode(buf []byte) (*DecodedMultihash, error) {
if len(buf) < 2 {
return nil, ErrTooShort
}
var err error
var code, length uint64
code, buf, err = uvarint(buf)
if err != nil {
return nil, err
}
length, buf, err = uvarint(buf)
if err != nil {
return nil, err
}
if length > math.MaxInt32 {
return nil, errors.New("digest too long, supporting only <= 2^31-1")
}
dm := &DecodedMultihash{
Code: code,
Name: Codes[code],
Length: int(length),
Digest: buf,
}
if len(dm.Digest) != dm.Length {
return nil, ErrInconsistentLen{dm}
}
return dm, nil
}
// Encode a hash digest along with the specified function code.
// Note: the length is derived from the length of the digest itself.
func Encode(buf []byte, code uint64) ([]byte, error) {
if !ValidCode(code) {
return nil, ErrUnknownCode
}
start := make([]byte, 2*binary.MaxVarintLen64, 2*binary.MaxVarintLen64+len(buf))
spot := start
n := binary.PutUvarint(spot, code)
spot = start[n:]
n += binary.PutUvarint(spot, uint64(len(buf)))
return append(start[:n], buf...), nil
}
// EncodeName is like Encode() but providing a string name
// instead of a numeric code. See Names for allowed values.
func EncodeName(buf []byte, name string) ([]byte, error) {
return Encode(buf, Names[name])
}
// ValidCode checks whether a multihash code is valid.
func ValidCode(code uint64) bool {
_, ok := Codes[code]
return ok
}