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blockchain.py
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import functools
import json
from utility.hash_util import hash_block
from block import Block
from transaction import Transaction
from utility.verification import Verification
from wallet import Wallet
import requests
MINING_REWARD = 10
class Blockchain:
def __init__(self, public_key , node_id):
genesis_block = Block(0, '', [], 100, 0)
# Initializing out {empty} blockchain list
self.chain = [genesis_block]
self.__open_transactions = []
self.public_key = public_key
self.__peer_nodes = set()
self.node_id = node_id
self.resolve_conflicts = False
self.load_data()
@property
def chain(self):
return self.__chain[:]
@chain.setter
def chain(self, val):
self.__chain = val
def get_open_transactions(self):
return self.__open_transactions[:]
def load_data(self):
try:
with open("blockchain-{}.txt".format(self.node_id), 'r') as f:
# # IN JSON(long and complicated code due to conversion in string)
f_content = f.readlines()
blockchain = json.loads(f_content[0][:-1])
updated_blockchain = []
for block in blockchain:
converted_tx = [Transaction(tx['sender'], tx['recipient'], tx['signature'], tx['amount']) for tx in block['transactions']]
updated_block = Block(block['index'], block['previous_hash'], converted_tx, block['proof'], block['time'])
updated_blockchain.append(updated_block)
self.chain = updated_blockchain
open_transactions = json.loads(f_content[1][:-1])
updated_transactions = []
for tx in open_transactions:
updated_transaction = Transaction(tx['sender'], tx['recipient'], tx['signature'], tx['amount'])
updated_transactions.append(updated_transaction)
self.__open_transactions = updated_transactions
peer_nodes = json.loads(f_content[2])
self.__peer_nodes = set(peer_nodes)
# # IN PICKLE (easy and short code as no conversion in datatype but saves as binary code which is nor human readable)
# file_content = pickle.loads(f.read())
# global blockchain
# global open_transactions
# blockchain = file_content['chain']
# print("BLOCKCHAIN", blockchain)
# open_transactions = file_content['ot']
# print('OPEN_TRANSACTIONS', open_transactions)
# print(file_content)
except (IOError, IndexError):
print("Handled Error...")
finally:
print("Cleanup!")
def save_data(self):
try:
with open("blockchain-{}.txt".format(self.node_id), "w") as f:
# # IN JSON(long and complicated code due to conversion in string)
savable_chain = [block.__dict__ for block in [ Block(block_el.index, block_el.previous_hash, [tx.__dict__ for tx in block_el.transactions],block_el.proof, block_el.time) for
block_el in self.__chain]]
savable_tx = [tx.__dict__ for tx in self.__open_transactions]
f.write(json.dumps(savable_chain))
f.write('\n')
f.write(json.dumps(savable_tx))
f.write('\n')
f.write(json.dumps(list(self.__peer_nodes)))
# # IN PICKLE (easy and short code as no conversion in datatype but saves as binary code which is nor human readable)
# save_data = {
# 'chain':blockchain,
# 'ot': open_transactions
# }
# f.write(pickle.dumps(save_data ))
except IOError:
print("Saving failed!")
def proof_of_work(self):
last_block = self.__chain[-1]
last_hash = hash_block(last_block)
proof = 0
while not Verification.valid_proof(self.__open_transactions, last_hash, proof):
proof += 1
return proof
def get_balance(self, sender=None):
"""Returns the balance of the participant in the blockchain."""
if sender == None:
if self.public_key == None:
return None
participant = self.public_key
else:
participant = sender
# Send coins in chain
tx_sender = [[tx.amount for tx in block.transactions if tx.sender==participant] for block in self.__chain]
print("SENDER", tx_sender)
# Send coins in open
open_tx_sender = [tx.amount for tx in self.__open_transactions if tx.sender==participant]
tx_sender.append(open_tx_sender)
print(tx_sender)
print(open_tx_sender)
amount_send = functools.reduce(lambda tx_sum,tx_amt: tx_sum+sum(tx_amt) if len(tx_amt) > 0 else tx_sum+0, tx_sender,0)
# Received coims
tx_recipient = [[tx.amount for tx in block.transactions if tx.recipient == participant] for block in self.__chain]
amount_recieved = functools.reduce(lambda tx_sum,tx_amt: tx_sum+sum(tx_amt) if len(tx_amt) > 0 else tx_sum+0, tx_recipient,0)
# Return total amount
balance = amount_recieved - amount_send
return balance
def get_last_blockchain_value(self):
"""Returns the last value of the current value."""
if len(self.__chain) < 1:
return None
return self.__chain[-1]
def add_transaction(self, recipient, sender, signature, amount=1.0, is_receiving = False):
"""Append a new value as well as the last value to the blockchain.
Arguments:
:sender: The sender of the coins.
:recipient: The recipient of the coins.
:amount: The amount of the coins send with the transaction {default = 1.0}"""
# if self.public_key == None:
# return False
transaction = Transaction(sender, recipient,signature, amount)
if Verification.verify_transaction(transaction, self.get_balance) :
self.__open_transactions.append(transaction)
self.save_data()
if not is_receiving:
for node in self.__peer_nodes:
url = 'http://{}/broadcast-transaction'.format(node)
try:
response = requests.post(url, json={'sender': sender, 'recipient': recipient, 'amount': amount, 'signature': signature})
if response.status_code == 400 or response.status_code == 500:
print('Transaction declined, needs resolving')
return False
except requests.exceptions.ConnectionError:
continue
return True
return False
def mine_block(self):
"""Mine a new block."""
if self.public_key == None:
return None
# last block
last_block = self.__chain[-1]
# hashing last block
hashed_block = hash_block(last_block)
proof = self.proof_of_work()
# reward for mining block
# reward_transaction = {'sender': 'MINING', 'recipient': owner, 'amount': MINING_REWARD}
reward_transaction = Transaction('MINING', self.public_key, '', MINING_REWARD)
# adding details in new block
copied_transations = self.__open_transactions[:]
for tx in copied_transations:
if not Wallet.verify_transaction(tx):
return None
copied_transations.append(reward_transaction)
block = Block(len(self.__chain), hashed_block, copied_transations, proof)
self.__chain.append(block)
self.__open_transactions = []
self.save_data()
for node in self.__peer_nodes:
url = 'http://{}/broadcast-block'.format(node)
converted_block = block.__dict__.copy()
converted_block['transactions'] = [tx.__dict__ for tx in converted_block['transactions']]
try:
response = requests.post(url,json={'block': converted_block})
if response.status_code == 400 or response.status_code == 500:
print("Block declined, needs resolving.")
if response.status_code == 409:
self.resolve_conflicts = True
except requests.exceptions.ConnectionError:
continue
return block
def add_block(self, block):
transactions = [Transaction(tx['sender'], tx['recipient'], tx['signature'], tx['amount']) for tx in block['transactions']]
proof_is_valid = Verification.valid_proof(transactions[:-1], block['previous_hash'], block['proof'])
hashes_match = hash_block(self.chain[-1]) == block['previous_hash']
if not proof_is_valid or not hashes_match:
return False
converted_block = Block(block['index'], block['previous_hash'], transactions, block['proof'], block['time'])
self.__chain.append(converted_block)
stored_transactions = self.__open_transactions[:]
for itx in block['transactions']:
for opentx in stored_transactions:
if opentx.sender == itx['sender'] and opentx.recipient == itx['recipient'] and opentx.amount == itx['amount'] and opentx.signature == itx['signature']:
try:
self.__open_transactions.remove(opentx)
except ValueError:
print('Item was already removed.')
self.save_data()
return True
def resolve(self):
winner_chain = self.chain
replace = False
for node in self.__peer_nodes:
url = 'http://{}/chain'.format(node)
try:
response = requests.get(url)
node_chain = response.json()
node_chain = [Block(block['index'], block['previous_hash'],[Transaction(tx['sender'], tx['recipient'], tx['signature'], tx['amount']) for tx in block['transactions']], block['proof'], block['time']) for block in node_chain]
node_chain_length = len(node_chain)
local_chain_length = len(winner_chain)
if node_chain_length > local_chain_length and Verification.verify_chain(node_chain):
winner_chain = node_chain
replace = True
except requests.exceptions.ConnectionError:
continue
self.resolve_conflicts = False
self.chain = winner_chain
if replace:
self.__open_transactions = []
self.save_data()
return replace
def add_peer_node(self,node):
"""Adds a new node to the peer node set.
Arguments:
:node: The node URL which should be added.
"""
self.__peer_nodes.add(node)
self.save_data()
def remove_peer_node(self, node):
"""Removes a node from the peer node set.
Arguments:
:node: The node URL which should be removed.
"""
self.__peer_nodes.discard(node)
self.save_data()
def get_peer_nodes(self):
"""Return a list of all connected peer nodes."""
return list(self.__peer_nodes)