prysm-pulse/shared/htrutils/htrutils.go
2021-08-10 14:55:24 -05:00

94 lines
3.7 KiB
Go

// Package htrutils defines HashTreeRoot utility functions.
package htrutils
import (
"bytes"
"encoding/binary"
"github.com/pkg/errors"
ethpb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
"github.com/prysmaticlabs/prysm/shared/bytesutil"
"github.com/prysmaticlabs/prysm/shared/hashutil"
"github.com/prysmaticlabs/prysm/shared/params"
)
// Uint64Root computes the HashTreeRoot Merkleization of
// a simple uint64 value according to the Ethereum
// Simple Serialize specification.
func Uint64Root(val uint64) [32]byte {
buf := make([]byte, 8)
binary.LittleEndian.PutUint64(buf, val)
root := bytesutil.ToBytes32(buf)
return root
}
// ForkRoot computes the HashTreeRoot Merkleization of
// a Fork struct value according to the Ethereum
// Simple Serialize specification.
func ForkRoot(fork *ethpb.Fork) ([32]byte, error) {
fieldRoots := make([][]byte, 3)
if fork != nil {
prevRoot := bytesutil.ToBytes32(fork.PreviousVersion)
fieldRoots[0] = prevRoot[:]
currRoot := bytesutil.ToBytes32(fork.CurrentVersion)
fieldRoots[1] = currRoot[:]
forkEpochBuf := make([]byte, 8)
binary.LittleEndian.PutUint64(forkEpochBuf, uint64(fork.Epoch))
epochRoot := bytesutil.ToBytes32(forkEpochBuf)
fieldRoots[2] = epochRoot[:]
}
return BitwiseMerkleize(hashutil.CustomSHA256Hasher(), fieldRoots, uint64(len(fieldRoots)), uint64(len(fieldRoots)))
}
// CheckpointRoot computes the HashTreeRoot Merkleization of
// a InitWithReset struct value according to the Ethereum
// Simple Serialize specification.
func CheckpointRoot(hasher HashFn, checkpoint *ethpb.Checkpoint) ([32]byte, error) {
fieldRoots := make([][]byte, 2)
if checkpoint != nil {
epochBuf := make([]byte, 8)
binary.LittleEndian.PutUint64(epochBuf, uint64(checkpoint.Epoch))
epochRoot := bytesutil.ToBytes32(epochBuf)
fieldRoots[0] = epochRoot[:]
ckpRoot := bytesutil.ToBytes32(checkpoint.Root)
fieldRoots[1] = ckpRoot[:]
}
return BitwiseMerkleize(hasher, fieldRoots, uint64(len(fieldRoots)), uint64(len(fieldRoots)))
}
// HistoricalRootsRoot computes the HashTreeRoot Merkleization of
// a list of [32]byte historical block roots according to the Ethereum
// Simple Serialize specification.
func HistoricalRootsRoot(historicalRoots [][]byte) ([32]byte, error) {
result, err := BitwiseMerkleize(hashutil.CustomSHA256Hasher(), historicalRoots, uint64(len(historicalRoots)), params.BeaconConfig().HistoricalRootsLimit)
if err != nil {
return [32]byte{}, errors.Wrap(err, "could not compute historical roots merkleization")
}
historicalRootsBuf := new(bytes.Buffer)
if err := binary.Write(historicalRootsBuf, binary.LittleEndian, uint64(len(historicalRoots))); err != nil {
return [32]byte{}, errors.Wrap(err, "could not marshal historical roots length")
}
// We need to mix in the length of the slice.
historicalRootsOutput := make([]byte, 32)
copy(historicalRootsOutput, historicalRootsBuf.Bytes())
mixedLen := MixInLength(result, historicalRootsOutput)
return mixedLen, nil
}
// SlashingsRoot computes the HashTreeRoot Merkleization of
// a list of uint64 slashing values according to the Ethereum
// Simple Serialize specification.
func SlashingsRoot(slashings []uint64) ([32]byte, error) {
slashingMarshaling := make([][]byte, params.BeaconConfig().EpochsPerSlashingsVector)
for i := 0; i < len(slashings) && i < len(slashingMarshaling); i++ {
slashBuf := make([]byte, 8)
binary.LittleEndian.PutUint64(slashBuf, slashings[i])
slashingMarshaling[i] = slashBuf
}
slashingChunks, err := Pack(slashingMarshaling)
if err != nil {
return [32]byte{}, errors.Wrap(err, "could not pack slashings into chunks")
}
return BitwiseMerkleize(hashutil.CustomSHA256Hasher(), slashingChunks, uint64(len(slashingChunks)), uint64(len(slashingChunks)))
}