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  }