diff options
| -rwxr-xr-x | .gitignore | 2 | ||||
| -rw-r--r-- | blockchain.py | 288 | ||||
| -rw-r--r-- | requirements.txt | 3 | ||||
| -rw-r--r-- | startserver.sh | 2 | ||||
| -rw-r--r-- | wsgi.py | 4 |
5 files changed, 299 insertions, 0 deletions
@@ -0,0 +1,2 @@ +__pycache__ +database/* diff --git a/blockchain.py b/blockchain.py new file mode 100644 index 0000000..8aab178 --- /dev/null +++ b/blockchain.py @@ -0,0 +1,288 @@ +import hashlib +import json +import re +import plyvel +from time import time +from urllib.parse import urlparse +from uuid import uuid4 + +import requests +from flask import Flask, jsonify, request + + +class Blockchain: + def __init__(self): + self.database = plyvel.DB("database/", create_if_missing=True) + self.current_message = [] + self.chain = [] + self.nodes = set() + + # create first block (genesis) + self.new_block(previous_hash='1', proof=100) + + def register_node(self, address): + """ + registers a new node + :param address: IP of node + """ + + if re.match(r'[0-9]+(?:\.[0-9]+){3}:[0-9]+', address): + parsed_url = urlparse(address) + if parsed_url.netloc: + self.nodes.add(parsed_url.netloc) + elif parsed_url.path: + self.nodes.add(parsed_url.path) + else: + raise ValueError('Invalid URL') + else: + raise ValueError('Invalid URL') + + def valid_chain(self, chain): + """ + check if a block 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 hash + last_block_hash = self.hash(last_block) + if block['previous_hash'] != last_block_hash: + return False + + # check proof + if not self.valid_proof(last_block['proof'], block['proof'], last_block_hash): + return False + + last_block = block + current_index += 1 + + return True + + def resolve_conflicts(self): + """ + Resolves conflict by replacing if other chain is longer + :return: true if replaced + """ + + neighbours = self.nodes + new_chain = None + + # only get the ones which are longer than own + max_length = len(self.chain) + + # get all chains from nodes and verify + 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 longer and valid + if length > max_length and self.valid_chain(chain): + max_length = length + new_chain = chain + + # replace if other is longer + if new_chain: + self.chain = new_chain + return True + + return False + + def new_block(self, proof, previous_hash): + """ + create new block in blockchain + :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(), + 'message': self.current_message, + 'proof': proof, + 'previous_hash': previous_hash or self.hash(self.chain[-1]), + } + + # reset the list of messages + self.current_message = [] + + self.chain.append(block) + self.database.put(b'key', b'value') + return block + + def new_message(self, sender, recipient, message): + """ + creates a new message (gets into next mined block) + :param sender: Address of the Sender + :param recipient: Address of the Recipient + :param message: Message + :return: The index of the Block that will hold this message + """ + self.current_message.append({ + 'sender': sender, + 'recipient': recipient, + 'message': message, + }) + + return self.last_block['index'] + 1 + + @property + def last_block(self): + return self.chain[-1] + + @staticmethod + def hash(block): + """ + hash the block (sha256) + :param block: Block + """ + + # sort dict + block_string = json.dumps(block, sort_keys=True).encode() + return hashlib.sha256(block_string).hexdigest() + + def proof_of_work(self, last_block): + """ + create proof + :param last_block: <dict> last Block + :return: <int> + """ + + last_proof = last_block['proof'] + last_hash = self.hash(last_block) + + proof = 0 + while self.valid_proof(last_proof, proof, last_hash) is False: + proof += 1 + + return proof + + @staticmethod + def valid_proof(last_proof, proof, last_hash): + """ + Validates the Proof + :param last_proof: <int> Previous Proof + :param proof: <int> Current Proof + :param last_hash: <str> The hash of the Previous Block + :return: <bool> True if correct, False if not. + """ + + guess = f'{last_proof}{proof}{last_hash}'.encode() + guess_hash = hashlib.sha256(guess).hexdigest() + return guess_hash[:4] == "0000" + + +# start node +application = Flask(__name__) + +# generate node ID +node_identifier = str(uuid4()).replace('-', '') + +# create blockchain +blockchain = Blockchain() + + +@application.route('/mine', methods=['GET']) +def mine(): + # run the proof of work algorithm to get the next proof + last_block = blockchain.last_block + proof = blockchain.proof_of_work(last_block) + blockchain.new_message( + sender="0", + recipient=node_identifier, + message="", + ) + + # forge by adding block to chain + previous_hash = blockchain.hash(last_block) + block = blockchain.new_block(proof, previous_hash) + + response = { + 'answer': "New Block Forged", + 'index': block['index'], + 'message': block['message'], + 'proof': block['proof'], + 'previous_hash': block['previous_hash'], + } + return jsonify(response), 200 + + +@application.route('/message/new', methods=['POST']) +def new_message(): + values = request.get_json() + + # check POST fields + required = ['sender', 'recipient', 'message'] + if not all(k in values for k in required): + return 'Missing values', 400 + + # new message to blockchain + index = blockchain.new_message( + values['sender'], values['recipient'], values['message']) + + response = {'answer': f'Message will be added to Block {index}'} + return jsonify(response), 201 + + +@application.route('/chain', methods=['GET']) +def full_chain(): + response = { + 'chain': blockchain.chain, + 'length': len(blockchain.chain), + } + return jsonify(response), 200 + + +@application.route('/nodes/list', methods=['GET']) +def getNodeList(): + response = { + 'total_nodes': list(blockchain.nodes) + } + return jsonify(response), 200 + + +@application.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 = { + 'answer': 'New nodes have been added', + 'total_nodes': list(blockchain.nodes), + } + return jsonify(response), 201 + + +@application.route('/nodes/resolve', methods=['GET']) +def consensus(): + replaced = blockchain.resolve_conflicts() + + if replaced: + response = { + 'answer': 'Our chain was replaced', + 'new_chain': blockchain.chain + } + else: + response = { + 'answer': 'Our chain is authoritative', + 'chain': blockchain.chain + } + + return jsonify(response), 200 diff --git a/requirements.txt b/requirements.txt new file mode 100644 index 0000000..ad7bd04 --- /dev/null +++ b/requirements.txt @@ -0,0 +1,3 @@ +flask +requests +plyvel
\ No newline at end of file diff --git a/startserver.sh b/startserver.sh new file mode 100644 index 0000000..6c8be82 --- /dev/null +++ b/startserver.sh @@ -0,0 +1,2 @@ +#!/bin/bash +gunicorn --bind 0.0.0.0:5000 wsgi
\ No newline at end of file @@ -0,0 +1,4 @@ +from blockchain import application + +if __name__ == "__main__": + application.run() |