python 区块链程序

python 区块链程序

学习了：https://mp.weixin.qq.com/s?__biz=MzAxODcyNjEzNQ==&mid=2247484921&idx=1&sn=fd7a0b10fce7b5d78c477438a0c7040e&pass_ticket=VRQ4Gl2qVWVdx9L7zKnwzmZ%2F3afkWrOb1mO8UAgklOnyOh1LnDAzTkLvyduPgzWb

进行postman的post方法提交的时候，注意选择Body > raw 选择JSON(application/json)

pip 进行install的时候选择国内的源；

测试的时候使用pipenv 没有生效，后来改为修改文件，重写文件，然后启动两次；

源文件：

import hashlib
import json
from time import time
from uuid import uuid4
from flask import Flask, jsonify, request
from urllib.parse import urlparse
import requests

class Blockchain(object):
    def __init__(self):
        self.chain = []
        self.current_transactions = []
        self.new_block(previous_hash=1, proof=None)
        self.nodes = set()

    def register_node(self, address):
        parsed_url = urlparse(address)
        self.nodes.add(parsed_url.netloc)

    def valid_chain(self, chain):
        last_block = chain[0]
        current_index = 1
        while current_index < len(chain):
            block = chain[current_index]
            print(f'{last_block}')
            print(f'{block}')
            print('\n---------------\n')
            if block['previous_hash'] != self.hash(last_block):
                return False
            if not self.valid_proof(last_block['proof'], block['proof']):
                return False
            last_block = block
            current_index += 1
        return True

    def resolve_conflicts(self):
        neighbours = self.nodes
        new_chain = None
        max_length = len(self.chain)
        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

    def new_block(self, proof, previous_hash=None):
        block = {
            'index': len(self.chain) + 1,
            'timestamp': time(),
            'transactions': self.current_transactions,
            'proof': proof,
            'previous_hash': previous_hash or self.hash(self.chain[-1])
        }
        self.current_transactions = []
        self.chain.append(block)
        return block

    def new_transaction(self, sender, recipient, amount):
        self.current_transactions.append({
            'sender': sender,
            'recipient': recipient,
            'amount': amount
        })
        return self.last_block['index'] + 1

    @staticmethod
    def hash(block):
        block_string = json.dumps(block, sort_keys=True).encode()
        return hashlib.sha256(block_string).hexdigest()

    @property
    def last_block(self):
        return self.chain[-1]

    def proof_of_work(self, last_proof):
        proof = 0
        while self.valid_proof(last_proof, proof) is False:
            proof += 1
        return proof

    @staticmethod
    def valid_proof(last_proof, proof):
        guess = f'{last_proof}{proof}'.encode()
        guess_hash = hashlib.sha256(guess).hexdigest()
        return guess_hash[:4] == ""

app = Flask(__name__)
node_identifier = str(uuid4()).replace('-', '')
blockchain = Blockchain()

@app.route('/mine', methods=['GET'])
def mine():
    last_block = blockchain.last_block
    last_proof = last_block['proof']
    proof = blockchain.proof_of_work(last_proof)
    blockchain.new_transaction(
        sender="",
        recipient=node_identifier,
        amount=1
    )
    block = blockchain.new_block(proof)
    response = {
        'message': "New Block Forged",
        'index': block['index'],
        'transactions': block['transactions'],
        'proof': block['proof'],
        'previous_hash': block['previous_hash']
    }
    return jsonify(response), 200

@app.route('/transactions/new', methods=['POST'])
def new_transactions():
    values = request.get_json()
    print('*' * 20, values)
    required = ['sender', 'recipient', 'amount']
    if not all(k in values for k in required):
        return "Missing Values", 400
    index = blockchain.new_transaction(values['sender'], values['recipient'], values['amount'])
    response = {'message': f'Transaction will be added to Block{index}'}
    return jsonify(response), 201

@app.route('/chain', methods=['GET'])
def full_chain():
    response = {
        'chain': blockchain.chain,
        'length': len(blockchain.chain)
    }
    return jsonify(response), 200

@app.route('/nodes/register', methods=['POST'])
def register_nodes():
    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:
        blockchain.register_node(node)
    response = {
        'message': 'New nodes have been added',
        'total_nodes': list(blockchain.nodes)
    }
    return jsonify(response), 201

@app.route('/nodes/resolve', methods=['GET'])
def consensus():
    replaced = blockchain.resolve_conflicts()
    if replaced:
        response = {
            'message': 'Our chain was replaced',
            'new_chain': blockchain.chain
        }
    else:
        response = {
            'message': 'Our chain is authoritative',
            'chain': blockchain.chain
        }
    return jsonify(response), 200

if __name__ == '__main__':
    app.run('0.0.0.0', port=5001)