-
- -

Source code for QUANTAXIS.QAWeb.chain

-import hashlib
-import json
-from time import time
-from typing import Any, Dict, List, Optional
-from urllib.parse import urlparse
-from uuid import uuid4
-
-import requests
-from flask import Flask, jsonify, request
-
-#from https://github.com/xilibi2003/blockchain/blob/master/blockchain.py
-
-
-
[docs]class Blockchain:
-    def __init__(self):
-        self.current_transactions = []
-        self.chain = []
-        self.nodes = set()
-
-        # 创建创世块
-        self.new_block(previous_hash='1', proof=100)
-
-
[docs]    def register_node(self, address: str) -> None:
-        """
-        Add a new node to the list of nodes
-        :param address: Address of node. Eg. 'http://192.168.0.5:5000'
-        """
-
-        parsed_url = urlparse(address)
-        self.nodes.add(parsed_url.netloc)

-
-
[docs]    def valid_chain(self, chain: List[Dict[str, Any]]) -> bool:
-        """
-        Determine if a given blockchain is valid
-        :param chain: A blockchain
-        :return: True if valid, False if not
-        """
-
-        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")
-            # Check that the hash of the block is correct
-            if block['previous_hash'] != self.hash(last_block):
-                return False
-
-            # Check that the Proof of Work is correct
-            if not self.valid_proof(last_block['proof'], block['proof']):
-                return False
-
-            last_block = block
-            current_index += 1
-
-        return True

-
-
[docs]    def resolve_conflicts(self) -> bool:
-        """
-        共识算法解决冲突
-        使用网络中最长的链.
-        :return:  如果链被取代返回 True, 否则为False
-        """
-
-        neighbours = self.nodes
-        new_chain = None
-
-        # We're only looking for chains longer than ours
-        max_length = len(self.chain)
-
-        # Grab and verify the chains from all the nodes in our network
-        for node in neighbours:
-            response = requests.get(f'http://{node}/chain')
-
-            if response.status_code == 200:
-                length = response.json()['length']
-                chain = response.json()['chain']
-
-                # Check if the length is longer and the chain is valid
-                if length > max_length and self.valid_chain(chain):
-                    max_length = length
-                    new_chain = chain
-
-        # Replace our chain if we discovered a new, valid chain longer than ours
-        if new_chain:
-            self.chain = new_chain
-            return True
-
-        return False

-
-
[docs]    def new_block(self, proof: int, previous_hash: Optional[str]) -> Dict[str, Any]:
-        """
-        生成新块
-        :param proof: The proof given by the Proof of Work algorithm
-        :param previous_hash: Hash of previous Block
-        :return: New Block
-        """
-
-        block = {
-            'index': len(self.chain) + 1,
-            'timestamp': time(),
-            'transactions': self.current_transactions,
-            'proof': proof,
-            'previous_hash': previous_hash or self.hash(self.chain[-1]),
-        }
-
-        # Reset the current list of transactions
-        self.current_transactions = []
-
-        self.chain.append(block)
-        return block

-
-
[docs]    def new_transaction(self, sender: str, recipient: str, amount: int) -> int:
-        """
-        生成新交易信息，信息将加入到下一个待挖的区块中
-        :param sender: Address of the Sender
-        :param recipient: Address of the Recipient
-        :param amount: Amount
-        :return: The index of the Block that will hold this transaction
-        """
-        self.current_transactions.append({
-            'sender': sender,
-            'recipient': recipient,
-            'amount': amount,
-        })
-
-        return self.last_block['index'] + 1

-
-    @property
-    def last_block(self) -> Dict[str, Any]:
-        return self.chain[-1]
-
-
[docs]    @staticmethod
-    def hash(block: Dict[str, Any]) -> str:
-        """
-        生成块的 SHA-256 hash值
-        :param block: Block
-        """
-
-        # We must make sure that the Dictionary is Ordered, or we'll have inconsistent hashes
-        block_string = json.dumps(block, sort_keys=True).encode()
-        return hashlib.sha256(block_string).hexdigest()

-
-
[docs]    def proof_of_work(self, last_proof: int) -> int:
-        """
-        简单的工作量证明:
-         - 查找一个 p' 使得 hash(pp') 以4个0开头
-         - p 是上一个块的证明,  p' 是当前的证明
-        """
-
-        proof = 0
-        while self.valid_proof(last_proof, proof) is False:
-            proof += 1
-
-        return proof

-
-
[docs]    @staticmethod
-    def valid_proof(last_proof: int, proof: int) -> bool:
-        """
-        验证证明: 是否hash(last_proof, proof)以4个0开头
-        :param last_proof: Previous Proof
-        :param proof: Current Proof
-        :return: True if correct, False if not.
-        """
-
-        guess = f'{last_proof}{proof}'.encode()
-        guess_hash = hashlib.sha256(guess).hexdigest()
-        return guess_hash[:4] == "0000"

-
-
-# Instantiate the Node
-app = Flask(__name__)
-
-# Generate a globally unique address for this node
-node_identifier = str(uuid4()).replace('-', '')
-
-# Instantiate the Blockchain
-blockchain = Blockchain()
-
-
-
[docs]@app.route('/mine', methods=['GET'])
-def mine():
-    # We run the proof of work algorithm to get the next proof...
-    last_block = blockchain.last_block
-    last_proof = last_block['proof']
-    proof = blockchain.proof_of_work(last_proof)
-
-    # 给工作量证明的节点提供奖励.
-    # 发送者为 "0" 表明是新挖出的币
-    blockchain.new_transaction(
-        sender="0",
-        recipient=node_identifier,
-        amount=1,
-    )
-
-    # Forge the new Block by adding it to the chain
-    block = blockchain.new_block(proof, None)
-
-    response = {
-        'message': "New Block Forged",
-        'index': block['index'],
-        'transactions': block['transactions'],
-        'proof': block['proof'],
-        'previous_hash': block['previous_hash'],
-    }
-    return jsonify(response), 200

-
-
-
[docs]@app.route('/transactions/new', methods=['POST'])
-def new_transaction():
-    values = request.get_json()
-
-    # 检查POST数据
-    required = ['sender', 'recipient', 'amount']
-    if not all(k in values for k in required):
-        return 'Missing values', 400
-
-    # Create a new Transaction
-    index = blockchain.new_transaction(values['sender'], values['recipient'], values['amount'])
-
-    response = {'message': f'Transaction will be added to Block {index}'}
-    return jsonify(response), 201

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

-
-
-
[docs]@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

-
-
-
[docs]@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__':
-    from argparse import ArgumentParser
-
-    parser = ArgumentParser()
-    parser.add_argument('-p', '--port', default=5000, type=int, help='port to listen on')
-    args = parser.parse_args()
-    port = args.port
-
-    app.run(host='127.0.0.1', port=port)
-
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- -