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blockchain.py
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blockchain.py
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from functools import reduce
import json
import pickle # python object to binary data
import requests
from block import Block
from transaction import Transaction
from wallet import Wallet
from utility.verification import Verification
from utility.hash_util import hash_block, hash_string_256
class Blockchain:
MINING_REWARD = 10 # should be given to the people who mined the block
def __init__(self, public_key, node_id):
# Our starting block for blockchain
genesis_block = Block(0, '', [], 100, 0)
# Initializing our (empty) blockchain list
self.chain = [genesis_block]
# Unhandled transactions
self.__open_transactions = []
self.public_key = public_key
self.__peer_nodes = set() # every node is unique!
self.node_id = node_id
self.need_resolve_conflicts = False
self.load_data()
""" Getter """
@property
def chain(self):
""" self.__cahin is automatically created by @property.
No need to declaire it. """
return self.__chain[:] # just retrun a copy
""" Setter """
@chain.setter
def chain(self, val):
self.__chain = val
# pass # immutable
def get_open_transactions(self):
return self.__open_transactions[:]
def load_data(self):
''' this stores as string human readable formate
try:
with open('blockchain-{}.txt'.format(self.node_id), mode='r') as f:
file_content = f.readlines()
# :-1 get rid of '\n'
blockchain = json.loads(file_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['timestamp'])
updated_blockchain.append(updated_block)
self.chain = updated_blockchain
open_transactions = json.loads(file_content[1][:-1])
update_transactions = []
for tx in open_transactions:
updated_transaction = Transaction(
tx['sender'], tx['recipient'], tx['signature'],
tx['amount'])
update_transactions.append(updated_transaction)
self.__open_transactions = update_transactions
peer_nodes = json.loads(file_content[2])
self.__peer_nodes = set(peer_nodes)
except (IOError, IndexError):
print('Handled exception...')
pass
finally:
print('Cleanup!') '''
try:
with open('chain.p',mode='rb') as chainfile:
self.chain = pickle.load(chainfile)
except(IOError,IndexError):
print('loding chain fail')
try:
with open('openTX.p',mode='rb') as openTxfile:
self.__open_transactions = pickle.load(openTxfile)
except(IOError,IndexError):
print('loding openTx failed')
try:
with open('peerNodes.p',mode='rb') as peer_file:
self.__peer_nodes = pickle.load(peer_file)
except(IOError,IndexError):
print('peer nodes not loded')
# Store the blockchain and open transactions to the file
# This is called whenever we mine a block or add a transaction
def save_data(self):
"""Save blockchain + open transactions snapshot to a file."""
""" this save as the string human readable
try:
with open('blockchain-{}.txt'.format(self.node_id), mode='w') as f:
saveable_chain = [block.__dict__ for block in
[Block(bl.index, bl.previous_hash,
[tx.__dict__ for tx in
bl.transactions],
bl.proof, bl.timestamp) for bl in
self.__chain]]
f.write(json.dumps(saveable_chain))
f.write('\n')
saveable_tx = [tx.__dict__ for tx in
self.__open_transactions]
f.write(json.dumps(saveable_tx))
f.write('\n')
f.write(json.dumps(list(self.__peer_nodes)))
except (IOError, IndexError):
print('Saving Failed!') """
try:
with open('chain.p',mode='wb') as file_chain:
pickle.dump(self.__chain,file_chain)
except (IOError, IndexError):
print('saving chain failed')
try:
with open('openTX.p',mode='wb') as openTx_file:
pickle.dump(self.__open_transactions,openTx_file)
except (IOError, IndexError):
print('saving open transaction failed')
try:
with open('peerNodes.p',mode='wb') as peer_file:
pickle.dump(self.__peer_nodes,peer_file)
except( IOError,IndentationError):
print('saving peer nods 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):
""" Calculate how much a participant send, as well as how much a
participant received. """
if sender is None:
if self.public_key is None:
return None
participant = self.public_key
else:
participant = sender
tx_sender = [[tx.amount for tx in block.transactions
if tx.sender == participant] for block in self.__chain]
open_tx_sender = [tx.amount
for tx in
self.__open_transactions if tx.sender == participant]
tx_sender.append(open_tx_sender)
print(tx_sender)
amount_sent = reduce(
lambda tx_sum, tx_amt: tx_sum + sum(tx_amt) if len(tx_amt) > 0
else tx_sum+0, tx_sender, 0)
tx_recipient = [[tx.amount for tx in block.transactions
if tx.recipient == participant] for block in
self.__chain]
amount_received = reduce(
lambda tx_sum, tx_amt: tx_sum + sum(tx_amt) if len(tx_amt) > 0
else tx_sum+0, tx_recipient, 0)
# Return the total balance
return amount_received - amount_sent
def get_last_blockchain_value(self):
""" Returns the last value of the current blockchain. """
if len(self.__chain) < 1:
return None
return self.__chain[-1]
def add_transaction(self, recipient, sender, signature, amount,memo,is_receiving=False):
""" Append a new value as well as the last blockchain value to the
blockchain.
Arguments:
:sender: The sender of the coins.
:recipient: The recipient of the coins.
:amount: The amount of coins sent with the transaction
:memo : String set by the sender
"""
# if self.public_key == None:
# return False
transaction = Transaction(sender, recipient, signature, amount, memo)
if Verification.verify_transaction(transaction, self.get_balance):
self.__open_transactions.append(transaction)
self.save_data()
# broadcast results to peer nodes
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,'memo':memo})
if (response.status_code == 400 or
response.status_code == 500):
print('Transaction declined, needs resolving')
return False
except requests.exceptions.ConnectionError:
continue # if a node failed, go through other nodes
return True
return False
def mine_block(self):
""" Create a new block and add open transactions to it. """
if self.public_key is None:
return None
# Fetch the currently last block of the blockchain
last_block = self.__chain[-1]
# Hash the last block (=> to be able to compare it to the stored hash
# value)
hashed_block = hash_block(last_block)
proof = self.proof_of_work()
# reward_transaction = {
# 'sender': 'MINING',
# 'recipient': owner,
# 'amount': MINING_REWARD
# }
reward_transaction = Transaction(
'MINING', self.public_key, '', self.MINING_REWARD,'for mine')
# range selector to make a copy
copied_transactions = self.__open_transactions[:]
for tx in copied_transactions:
if not Wallet.verify_transaction(tx):
return None
copied_transactions.append(reward_transaction)
block = Block(len(self.__chain), hashed_block,
copied_transactions, 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.need_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'],tx['meomo']) for
tx in block['transactions']]
# check ours
proof_is_valid = Verification.valid_proof(
transactions[:-1], block['previous_hash'], block['proof'])
# check peers
hashes_match = hash_block(self.chain[-1]) == block['previous_hash']
if not proof_is_valid or not hashes_match:
return False
# block is still a dictionary, need to convert first
converted_block = Block(
block['index'], block['previous_hash'], transactions,
block['proof'], block['timestamp'])
self.__chain.append(converted_block)
# update open transactions before saving data
stored_transactions = self.__open_transactions[:]
for incoming_tx in block['transactions']:
for opentx in stored_transactions:
if (opentx.sender == incoming_tx['sender'] and
opentx.recipient == incoming_tx['recipient'] and
opentx.amount == incoming_tx['amount'] and
opentx.signature == incoming_tx['signature'] and
opentx.memo == incoming_tx['memo']):
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'],
tx['memo']) for tx in
block['transactions']],
block['proof'], block['timestamp']) 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.chain = winner_chain
self.need_resolve_conflicts = False
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) # using discard(): if no element, do nothing
self.save_data()
def get_peer_nodes(self):
"""Return a list of all connected peer nodes."""
return list(self.__peer_nodes)