github.com/snowblossomcoin/go-ethereum@v1.9.25/core/types/derive_sha.go (about) 1 // Copyright 2014 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package types 18 19 import ( 20 "bytes" 21 22 "github.com/ethereum/go-ethereum/common" 23 "github.com/ethereum/go-ethereum/rlp" 24 ) 25 26 type DerivableList interface { 27 Len() int 28 GetRlp(i int) []byte 29 } 30 31 // Hasher is the tool used to calculate the hash of derivable list. 32 type Hasher interface { 33 Reset() 34 Update([]byte, []byte) 35 Hash() common.Hash 36 } 37 38 func DeriveSha(list DerivableList, hasher Hasher) common.Hash { 39 hasher.Reset() 40 keybuf := new(bytes.Buffer) 41 42 // StackTrie requires values to be inserted in increasing 43 // hash order, which is not the order that `list` provides 44 // hashes in. This insertion sequence ensures that the 45 // order is correct. 46 for i := 1; i < list.Len() && i <= 0x7f; i++ { 47 keybuf.Reset() 48 rlp.Encode(keybuf, uint(i)) 49 hasher.Update(keybuf.Bytes(), list.GetRlp(i)) 50 } 51 if list.Len() > 0 { 52 keybuf.Reset() 53 rlp.Encode(keybuf, uint(0)) 54 hasher.Update(keybuf.Bytes(), list.GetRlp(0)) 55 } 56 for i := 0x80; i < list.Len(); i++ { 57 keybuf.Reset() 58 rlp.Encode(keybuf, uint(i)) 59 hasher.Update(keybuf.Bytes(), list.GetRlp(i)) 60 } 61 return hasher.Hash() 62 }