# -*- coding: utf-8 -*- import hashlib import json from argparse import ArgumentParser from time import time from urllib.parse import urlparse from uuid import uuid4 import requests from flask import Flask, jsonify, request # 区块的结构 # { # # 序号 # "index": 0, # # 时间戳 # "timestamp": "", # # 交易信息 # "transactions": [ # { # # 交易的发送者 # "sender": "", # # 交易的接收者 # "recipient": "", # # 交易的金额 # "amount": 5 # } # # ], # # 工作量证明 # "proof": "", # # 上一个区块的 Hash值 # "previous_hash": "" # } class Blockchain: # 初始化 def __init__(self): self.chain = [] self.current_transactions = [] # 保存节点的信息 self.nodes = set() # 创建一个创世纪的区块定义 self.new_block(proof=100, previous_hash=1) # 验证链为有效链 -> Hash值和工作量证明是否有效 def valid_chain(self, chain) -> bool: last_block = chain[0] current_index = 1 while current_index < len(chain): block = chain[current_index] # Hash 不一致, 则校验不通过, 是虚假的信息 if block['previous_hash'] != self.hash(last_block): return False # 工作量证明可能不满足, 不满足 "0000"开头的 if not self.valid_proof(last_block['proof'], block['proof']): return False last_block = block current_index += 1 return True # 共识机制 解决多个节点的冲突问题 def resolve_conflicts(self) -> bool: # 使用当前链的长度和附近节点的链的长度进行对比, 选择最长的链进行继续工作 neighbours = self.nodes max_length = len(self.chain) new_chain = None for node in neighbours: response = requests.get(f'http://{node}/chain') if response.status_code == 200: length = response.json()['length'] chain = response.json()['chain'] if length > max_length and self.valid_chain(chain): max_length = length new_chain = chain if new_chain: self.chain = new_chain return True return False # 注册一个节点 def register_node(self, address: str): # 解析节点信息 127.0.0.1:5001, 保存到 nodes 里面 parsed_url = urlparse(address) self.nodes.add(parsed_url.netloc) # 创建新的区块 def new_block(self, proof, previous_hash=None): # 创建区块, 把交易信息加入区块 block = { 'index': len(self.chain) + 1, 'timestamp': time(), 'transactions': self.current_transactions, 'proof': proof, 'previous_hash': previous_hash or self.hash(self.last_block) } # 把交易信息清空 self.current_transactions = [] # 把区块加入到链中 self.chain.append(block) return block # 新添加一个交易 def new_transaction(self, sender, recipient, amount) -> int: # 把创建的交易信息作为一个交易记录[json], 放在交易列表里 self.current_transactions.append( { 'sender': sender, 'recipient': recipient, 'amount': amount } ) # 返回区块的索引 return self.last_block['index'] + 1 # (静态) 计算 Hash @staticmethod def hash(block): # json 排序转成 字符串, 然后进行编码 block_str = json.dumps(block, sort_keys=True).encode() # 使用 hash 函数进行 hash, 并返回摘要信息 return hashlib.sha256(block_str).hexdigest() # (属性) 获取最后一个区块 @property def last_block(self): return self.chain[-1] # 工作量证明 def proof_of_work(self, last_proof: int) -> int: proof = 0 while self.valid_proof(last_proof, proof) is False: proof += 1 # print(proof) return proof # 验证合规的工作量 比如以几个 0 开头, 这里先定义 4个0 @staticmethod def valid_proof(last_proof: int, proof: int) -> bool: # 字符串拼接并进行编码 -> 构建 guess guess = f'{last_proof}{proof}'.encode() # 获取 guess 的 hash 值 guess_hash = hashlib.sha256(guess).hexdigest() # print(guess_hash) return guess_hash[0:4] == "0000" app = Flask(__name__) block_chain = Blockchain() # UUID 来声明当前节点的ID node_identifier = str(uuid4()).replace('-', '') # 交易接口 @app.route('/transactions/new', methods=['POST']) def new_transaction(): # 拿到请求内容 values = request.get_json() # 检查请求字段是否完整 required = ["sender", "recipient", "amount"] if values is None: return "Missing values", 400 if not all(k in values for k in required): return "Missing values", 400 index = block_chain.new_transaction(values['sender'], values['recipient'], values['amount']) response = {"message": f'Transcation will be added to Block {index}'} return jsonify(response), 201 # 挖矿接口 @app.route('/mine', methods=['GET']) def mine(): # 传入上一个工作量证明, 来计算当前的工作量证明 last_block = block_chain.last_block last_proof = last_block['proof'] proof = block_chain.proof_of_work(last_proof) # 新添加一个交易, 这个交易就是给自己的奖励 block_chain.new_transaction(sender="0", recipient=node_identifier, amount=1) # 新建一个区块 block = block_chain.new_block(proof, None) # 封装返回信息 response = { "message": "New Block Forged", "index": block['index'], "transactions": block['transactions'], "proof": block['proof'], "previous_hash": block['previous_hash'] } return jsonify(response), 200 # 返回整个区块链信息 @app.route('/chain', methods=['GET']) def full_chain(): response = { 'chain': block_chain.chain, 'length': len(block_chain.chain) } return jsonify(response), 200 # 添加一个节点 @app.route('/nodes/register', methods=['POST']) def register_nodes(): # 获取节点信息 values = request.get_json() nodes = values.get("nodes") if nodes is None: return "Error: please supply a valid list of nodes", 400 for node in nodes: block_chain.register_node(node) response = { "message": "New nodes have bean added", "total_nodes": list(block_chain.nodes) } return jsonify(response), 201 # 共识机制, 解决冲突的接口 @app.route('/nodes/resolve', methods=['GET']) def consensus(): replaced = block_chain.resolve_conflicts() if replaced: response = { 'message': 'Our chain was replaced', 'new_chain': block_chain.chain } else: response = { 'message': 'Our chain is authoritative', 'chain': block_chain.chain } return jsonify(response), 200 if __name__ == '__main__': # 测试一下 工作量证明 # test_Pow = Blockchain() # test_Pow.proof_of_work(100) # 单机模式 # app.run(host='0.0.0.0', port=5000) # 多节点模式 , 通过命令行参数进行实现 # -p -port parser = ArgumentParser() parser.add_argument('-p', '-port', default=5000, type=int, help='port to listen to') args = parser.parse_args() port = args.port app.run(host='0.0.0.0', port=port)