DPOS 共识算法API接口实现

.gitignore

@@ -169,6 +169,7 @@ cython_debug/
 # Icon must end with two \r
 Icon
 
+
 # Thumbnails
 ._*
 
@@ -188,3 +189,4 @@ Network Trash Folder
 Temporary Items
 .apdisk
 
+.idea

DPOS/blockChain.py

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+# Implementation of a simple decentralized blockchain class with multiple nodes and DPoS consensus in the network
+
+import hashlib
+import json
+from datetime import datetime
+from urllib.parse import urlparse
+import requests
+from random import randint
+
+
+# Blockchain class
+class Blockchain(object):
+    
+    # Constructor which creates lists to store the blockchain and the transactions
+    def __init__(self):
+        
+        # List to store the blockchain
+        self.chain = []
+        
+        # List to store the unverified transactions
+        self.unverified_transactions = []
+        
+        # List to store verified transactions
+        self.verified_transactions = []
+        
+        # Genesis block
+        self.new_block(previous_hash=1)
+        
+        # Set containing the nodes in the network. Used set here to prevent the same node getting added again.
+        self.nodes = set()
+        
+        # List containing all the nodes along with their stake in the network
+        self.all_nodes = []
+        
+        # List of all the voting nodes in the network
+        self.voteNodespool = []
+        
+        # List which stores all the nodes in descending order of votes received
+        self.starNodespool = []
+        
+        # List to store the top 3 nodes with the highest (stake * votes_received)
+        self.superNodespool = []
+        
+        # List to store the address of the delegate nodes selected for mining process
+        self.delegates = []
+    
+    # Method to create a new block in the Blockchain
+    def new_block(self, previous_hash=None):
+        block = {
+            'index': len(self.chain) + 1,
+            'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S'),
+            'transactions': self.unverified_transactions,
+            'previous_hash': previous_hash or self.hash(self.chain[-1])
+        }
+        self.verified_transactions += self.unverified_transactions
+        print(self.verified_transactions)
+        self.unverified_transactions = []
+        
+        # appending the block at the end of the blockchain
+        self.chain.append(block)
+        return block
+    
+    # Method to add a new transaction in the next block
+    def new_transaction(self, sender, item_name, bill_amount):
+        self.unverified_transactions.append({
+            'Customer name': sender,
+            'Recipient': "Dexter's Coffee Shop",
+            'Item name': item_name,
+            'Total billing amount': bill_amount,
+            'timestamp': datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+        })
+        return self.last_block['index'] + 1
+    
+    @property
+    def last_block(self):
+        return self.chain[-1]
+    
+    # Static method to create an SHA-256 Hash of a given block
+    @staticmethod
+    def hash(block):
+        block_string = json.dumps(block, sort_keys=True).encode()
+        hash_val = hashlib.sha256(block_string).hexdigest()
+        return hash_val
+    
+    # Method to add node using its IP address to our Blockchain network.
+    def add_node(self, address, stake):
+        parsed_url = urlparse(address)
+        authority = stake
+        self.nodes.add((parsed_url.netloc, authority))
+    
+    # Method to simulate the voting process
+    def add_vote(self):
+        self.all_nodes = list(self.nodes)
+        
+        for x in self.all_nodes:
+            y = list(x)
+            y.append(x[1] * randint(0, 100))
+            self.voteNodespool.append(y)
+        
+        print(self.voteNodespool)
+    
+    # Method to select top three nodes based on voting results
+    def selection(self):
+        self.starNodespool = sorted(self.voteNodespool, key=lambda vote: vote[2], reverse=True)
+        print(self.starNodespool)
+        
+        for x in range(3):
+            self.superNodespool.append(self.starNodespool[x])
+        print(self.superNodespool)
+        
+        for y in self.superNodespool:
+            self.delegates.append(y[0])
+        print(self.delegates)
+    
+    # Method to sync the list
+    def sync(self):
+        r = requests.get('http://localhost:5000/delegates/show')
+        print(r)
+        
+        if r.status_code == 200:
+            delegates = r.json()['node_delegates']
+            self.delegates = delegates[0:3]
+            print(self.delegates)
+    
+    # Method to check if the chain is validated.
+    def valid_chain(self, chain):
+        last_block = chain[0]
+        current_index = 1
+        
+        while current_index < len(chain):
+            block = chain[current_index]
+            
+            # If the hash value of the current block isn't correct then return false
+            if block['previous_hash'] != self.hash(last_block):
+                return False
+            
+            last_block = block
+            current_index += 1
+        
+        return True
+    
+    # Method to replace the blockchain with the longest validated chain in the network.
+    def resolve_chain(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

DPOS/dpos_api.py

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+# Interacting with the Dexter's blockchain with multiple nodes using HTTP requests
+
+from flask import Flask, jsonify, request
+
+from blockChain import Blockchain
+
+# Initialise our node with identifier and instantiate the Blockchain class
+app = Flask(__name__)
+blockchain = Blockchain()
+
+
+# API endpoint to mine a block, it is an HTTP GET request
+@app.route('/mine', methods=['GET'])
+# Method to mine a block
+def mine():
+    # To ensure that only delegates elected by voting can mine a new block
+    current_port = "localhost:" + str(port)
+    if current_port in blockchain.delegates:
+        
+        # To ensure that a new block is mined only if there are atleast 2 transactions
+        if len(blockchain.unverified_transactions) >= 2:
+            last_block = blockchain.last_block
+            previous_hash = blockchain.hash(last_block)
+            block = blockchain.new_block(previous_hash)
+            
+            response = {
+                'message': "New block mined!",
+                'index': block['index'],
+                'transactions': block['transactions'],
+                'previous_hash': block['previous_hash']
+            }
+            print(len(blockchain.unverified_transactions))
+            return jsonify(response), 200
+        
+        else:
+            response = {
+                'message': 'Not enough transactions to mine a new block and add to chain!'
+            }
+            print(len(blockchain.unverified_transactions))
+            return jsonify(response), 400
+    else:
+        response = {
+            'message': 'You are not authorised to mine block! Only delegates can mine.'
+        }
+        return jsonify(response), 400
+
+
+# Endpoint for a new transaction
+@app.route('/transactions/new', methods=['POST'])
+def new_transaction():
+    values = request.get_json()
+    
+    required = ['Customer name', 'Item name', 'Total billing amount']
+    if not all(k in values for k in required):
+        return 'Missing values! Please enter customer name, item name and billing amount.', 400
+    
+    index = blockchain.new_transaction(values['Customer name'], values['Item name'], values['Total billing amount'])
+    
+    response = {
+        'message': f'Transaction will be added to block {index}'
+    }
+    return jsonify(response), 201
+
+
+# Endpoint for viewing the blockchain
+@app.route('/chain', methods=['GET'])
+def full_chain():
+    response = {
+        'chain': blockchain.chain,
+        'length': len(blockchain.chain)
+    }
+    return jsonify(response), 200
+
+
+# Endpoint for adding HTTP address of new nodes along with their stakes in the network.
+@app.route('/nodes/add', methods=['POST'])
+def add_nodes():
+    values = request.get_json()
+    required = ['nodes', 'stake']
+    
+    if not all(k in values for k in required):
+        return 'Error', 400
+    
+    blockchain.add_node(values['nodes'], values['stake'])
+    
+    response = {
+        'message': 'New nodes are added!',
+        'total_nodes': list(blockchain.nodes)
+    }
+    print(blockchain.nodes)
+    return jsonify(response), 201
+
+
+# Endpoint to start the voting process
+@app.route('/voting', methods=['GET'])
+def voting():
+    if port == 5000:
+        show_votes = blockchain.add_vote()
+        
+        response = {
+            'message': 'The voting results are as follows:',
+            'nodes': blockchain.voteNodespool
+        }
+        
+        return jsonify(response), 200
+    
+    else:
+        response = {
+            'message': 'You are not authorized to conduct the election process!'
+        }
+        return jsonify(response), 400
+
+
+# Endpoint to view the list of all three elected delegate nodes
+@app.route('/delegates/show', methods=['GET'])
+def delegates():
+    show_delegates = blockchain.selection()
+    
+    response = {
+        'message': 'The 3 delegate nodes selected for block mining are:',
+        'node_delegates': blockchain.delegates
+    }
+    return jsonify(response), 200
+
+
+# Endpoint to synchronise the list of elected delegates with all other nodes in the network
+@app.route('/delegates/sync', methods=['GET'])
+def sync_delegates():
+    sync_delegates = blockchain.sync()
+    
+    response = {
+        'message': 'The delegate nodes are:',
+        'node_delegates': blockchain.delegates
+    }
+    return jsonify(response), 200
+
+
+# Endpoint to resolve and replace current chain with the longest validated one,achieving consensus
+@app.route('/chain/resolve', methods=['GET'])
+def consensus():
+    replaced = blockchain.resolve_chain()
+    
+    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='Listening on port')
+    args = parser.parse_args()
+    port = args.port
+    app.run(host='0.0.0.0', port=port)

POW/blockChain.py

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+import hashlib
+import requests
+import json
+from hashlib import sha256
+from time import time
+from urllib.parse import urlparse
+
+
+class Blockchain(object):
+    def __init__(self):
+        self.chain = [{'index': 0,
+                       'timestamp': time(),
+                       'transactions': 0,
+                       'proof': 0,
+                       'previous_hash': 0}]
+        self.current_transactions = []
+        self.nodes = set()
+    
+    # create a new node based on url
+    def register_node(self, address):
+        parsed_url = urlparse(address)
+        self.nodes.add(parsed_url.netloc)
+    
+    # create a new block and add it to the chain.
+    def new_block(self, proof, previous_hash):
+        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
+    
+    # add a new transaction to the list of transactions.
+    def new_transaction(self, sender, recipient, amount):
+        self.current_transactions.append({
+            'sender': sender,
+            'recipient': recipient,
+            'amount': amount
+        })
+        
+        return self.last_block['index'] + 1
+    
+    # PoW algo that increments proof value until valid_proof returns true.
+    def proof_of_work(self, last_proof):
+        proof = 0
+        while self.valid_proof(last_proof, proof) is False:
+            proof += 1
+        
+        return proof
+    
+    # verify the current chain has not already been solved
+    def valid_chain(self, chain):
+        last_block = chain[0]
+        current_index = 1
+        
+        while current_index < len(chain):
+            block = chain[current_index]
+            if block['previous_hash'] != self.hash(last_block):
+                return False
+            
+            # verify values in the chain are correct
+            if not self.valid_proof(last_block['proof'], block['proof']):
+                return False
+            
+            last_block = block
+            current_index += 1
+        return True
+    
+    # consensus algo to prevent conflicts when multiple nodes are in a network
+    def resolve_conflicts(self):
+        neighbors = self.nodes
+        new_chain = None
+        max_length = len(self.chain)
+        
+        # check each node to find the longest chain
+        for node in neighbors:
+            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
+    
+    # checks if the hash has 4 leading zeros. returns boolean.
+    @staticmethod
+    def valid_proof(last_proof, proof):
+        guess = f'{last_proof}{proof}'.encode()
+        guess_hash = hashlib.sha256(guess).hexdigest()
+        # the addition of leading zeros can make a massive difference to the time required to find a solution.
+        return guess_hash[:4] == "0000"
+    
+    # hashes a block
+    @staticmethod
+    def hash(block):
+        block_string = json.dumps(block, sort_keys=True).encode()
+        return sha256(block_string).hexdigest()
+    
+    # returns the last block of the chain
+    @property
+    def last_block(self):
+        return self.chain[-1]

POW/pow_api.py

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+from flask import Flask, jsonify, request
+from uuid import uuid4
+from blockChain import Blockchain
+
+# Instantiate our Node
+app = Flask(__name__)
+
+# Generate a globally unique address for this node
+node_identifier = str(uuid4()).replace('-', '')
+
+# Instantiate the Blockchain
+blockchain = Blockchain()
+
+
+@app.route('/mine', methods=['GET'])
+def mine():
+    # run the PoW algo
+    last_block = blockchain.last_block
+    last_proof = last_block['proof']
+    proof = blockchain.proof_of_work(last_proof)
+    
+    # get reward for solving a block
+    blockchain.new_transaction(sender="0", recipient=node_identifier, amount=1)
+    
+    # add a new block to the chain
+    previous_hash = blockchain.hash(last_block)
+    block = blockchain.new_block(proof, previous_hash)
+    
+    # create response
+    response = {
+        'message': "New block forged",
+        'index': block['index'],
+        'transactions': block['transactions'],
+        'proof': block['proof'],
+        'previous_hash': block['previous_hash']
+    }
+    
+    # return response
+    return jsonify(response), 200
+
+
+@app.route('/transactions/new', methods=['POST'])
+def new_transaction():
+    # get values from request
+    values = request.get_json()
+    
+    # verify all values are present
+    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'])
+    
+    # create and return response
+    response = {'message': f'Transaction will be added to Block {index}'}
+    return jsonify(response), 200
+
+
+# return the full chain
+@app.route('/chain', methods=['GET'])
+def full_chain():
+    response = {
+        'chain': blockchain.chain,
+        'length': len(blockchain.chain),
+    }
+    return jsonify(response), 200
+
+
+# create a new node
+@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
+
+
+# consensus algo
+@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(host='0.0.0.0', port=5000)
+    from argparse import ArgumentParser
+    
+    parser = ArgumentParser()
+    parser.add_argument('-p', '--port', default=6000, type=int, help='Listening on port')
+    args = parser.parse_args()
+    port = args.port
+    app.run(host='0.0.0.0', port=port)