91 lines
2.7 KiB
Go
91 lines
2.7 KiB
Go
// Copyright 2023 The go-ethereum Authors
|
|
// This file is part of go-ethereum.
|
|
//
|
|
// go-ethereum is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// go-ethereum is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
package era
|
|
|
|
import (
|
|
"fmt"
|
|
"math/big"
|
|
|
|
"github.com/ethereum/go-ethereum/common"
|
|
ssz "github.com/ferranbt/fastssz"
|
|
)
|
|
|
|
// ComputeAccumulator calculates the SSZ hash tree root of the Era1
|
|
// accumulator of header records.
|
|
func ComputeAccumulator(hashes []common.Hash, tds []*big.Int) (common.Hash, error) {
|
|
if len(hashes) != len(tds) {
|
|
return common.Hash{}, fmt.Errorf("must have equal number hashes as td values")
|
|
}
|
|
if len(hashes) > MaxEra1Size {
|
|
return common.Hash{}, fmt.Errorf("too many records: have %d, max %d", len(hashes), MaxEra1Size)
|
|
}
|
|
hh := ssz.NewHasher()
|
|
for i := range hashes {
|
|
rec := headerRecord{hashes[i], tds[i]}
|
|
root, err := rec.HashTreeRoot()
|
|
if err != nil {
|
|
return common.Hash{}, err
|
|
}
|
|
hh.Append(root[:])
|
|
}
|
|
hh.MerkleizeWithMixin(0, uint64(len(hashes)), uint64(MaxEra1Size))
|
|
return hh.HashRoot()
|
|
}
|
|
|
|
// headerRecord is an individual record for a historical header.
|
|
//
|
|
// See https://github.com/ethereum/portal-network-specs/blob/master/history-network.md#the-header-accumulator
|
|
// for more information.
|
|
type headerRecord struct {
|
|
Hash common.Hash
|
|
TotalDifficulty *big.Int
|
|
}
|
|
|
|
// GetTree completes the ssz.HashRoot interface, but is unused.
|
|
func (h *headerRecord) GetTree() (*ssz.Node, error) {
|
|
return nil, nil
|
|
}
|
|
|
|
// HashTreeRoot ssz hashes the headerRecord object.
|
|
func (h *headerRecord) HashTreeRoot() ([32]byte, error) {
|
|
return ssz.HashWithDefaultHasher(h)
|
|
}
|
|
|
|
// HashTreeRootWith ssz hashes the headerRecord object with a hasher.
|
|
func (h *headerRecord) HashTreeRootWith(hh ssz.HashWalker) (err error) {
|
|
hh.PutBytes(h.Hash[:])
|
|
td := bigToBytes32(h.TotalDifficulty)
|
|
hh.PutBytes(td[:])
|
|
hh.Merkleize(0)
|
|
return
|
|
}
|
|
|
|
// bigToBytes32 converts a big.Int into a little-endian 32-byte array.
|
|
func bigToBytes32(n *big.Int) (b [32]byte) {
|
|
n.FillBytes(b[:])
|
|
reverseOrder(b[:])
|
|
return
|
|
}
|
|
|
|
// reverseOrder reverses the byte order of a slice.
|
|
func reverseOrder(b []byte) []byte {
|
|
for i := 0; i < 16; i++ {
|
|
b[i], b[32-i-1] = b[32-i-1], b[i]
|
|
}
|
|
return b
|
|
}
|