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blockchain.py
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blockchain.py
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import functools
import json
import hashlib
import requests
import pickle
from utility.hash_util import hash_block
from block import Block
from transaction import Transaction
from utility.verification import Verification
from wallet import Wallet
MINING_REWARD = 10
class Blockchain:
def __init__(self, public_key, node_id):
genesis_block = Block(0, "", [], 100, 0)
self.chain = [genesis_block]
self.__open_transactions = []
self.public_key = public_key
self.node_id = node_id
self.resolve_conflicts = False
self.__peer_nodes = set()
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), mode="r") as f:
file_content = f.readlines()
# file_content = pickle.loads(f.read())
if len(file_content) > 0:
# global block_chain
# global open_transactions
# block_chain = file_content["chain"]
# open_transactions = file_content["ot"]
self.chain = json.loads(file_content[0][:-1])
# block_chain = [Block(block["index"], block["previous_hash"], [ OrderedDict([("sender", tx["sender"]), ("recipient", tx["recipient"]), ("amount", tx["amount"])]) for tx in block["transactions"]], block["proof"], block["timestamp"]) for block in block_chain]
self.chain = [ Block(block["index"], block["previous_hash"], [ Transaction(tx["sender"], tx["recipient"], tx["signature"], tx["amount"]) for tx in block["transactions"]], block["proof"], block["timestamp"]) for block in self.__chain ]
# block_chain = [ {"previous_hash": block["previous_hash"], "index": block["index"], "proof": block["proof"], "transactions": [ OrderedDict([("sender", tx["sender"]), ("recipient", tx["recipient"]), ("amount", tx["amount"])]) for tx in block["transactions"]]} for block in block_chain]
self.__open_transactions = json.loads(file_content[1][:-1])
self.__open_transactions = [Transaction(tx["sender"], tx["recipient"], tx["signature"], tx["amount"]) for tx in self.__open_transactions]
# open_transactions = [OrderedDict([("sender", tx["sender"]), ("recipient", tx["recipient"]), ("amount", tx["amount"])]) for tx in open_transactions]
peer_nodes = json.loads(file_content[2])
self.__peer_nodes = set(peer_nodes)
except (FileNotFoundError, IndexError):
print("Handled Exception..")
def save_data(self):
try:
with open("blockchain-{}.txt".format(self.node_id), mode="w") as f:
"""
Both json and pickle can help us but pickle is more flexible because it does change the structure of our OdererdDict
Pickle also write our data as bytes not text
"""
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.timestamp) for block_el in self.__chain ]]
f.write(json.dumps(savable_chain))
f.write("\n")
savable_tx = [tx.__dict__ for tx in self.__open_transactions]
f.write(json.dumps(savable_tx))
f.write("\n")
f.write(json.dumps(list(self.__peer_nodes)))
# saved_data = {
# "chain": block_chain,
# "ot": open_transactions
# }
# f.write(pickle.dumps(saved_data))
except:
print("Saving failed")
def proof_of_work(self):
last_block = self.__chain[-1]
last_hash = hash_block(last_block)
proof_number = 0
while not Verification.valid_proof(self.__open_transactions, last_hash, proof_number):
proof_number += 1
return proof_number
def get_balance(self, sender=None):
if sender == None:
if self.public_key == 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_txt_sender = [txt.amount for txt in self.__open_transactions if txt.sender == participant]
tx_sender.append(open_txt_sender)
amount_sent = functools.reduce(lambda tx_sum, tx_amt: tx_sum + sum(tx_amt) if len(tx_amt) > 0 else tx_sum, tx_sender, 0)
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, tx_recipient, 0)
return amount_recieved - amount_sent
def get_last_blockchain_value(self):
if len(self.__chain) < 1:
return None
return self.__chain[-1]
def add_transaction(self, recipient, sender, signature, amount=1.0, is_recieving=False):
""" Append a new tranction
Arguments:
: sender: The sender of the coins
: recipient: The recipient of the coins
: amount: The amount of coins sent with the transaction (default = 1.0)
: Use OrderedDict to control the order of our dictionary to avoid invalid hash coincidence
"""
# transaction = {
# "sender": sender,
# "recipient": recipient,
# "amount": amount
# }
if self.public_key == None:
return False
transaction = Transaction(sender, recipient, signature, amount)
ver = Verification.verify_transaction(transaction, self.get_balance)
print("Verification: ", ver)
if ver:
self.__open_transactions.append(transaction)
self.save_data()
if not is_recieving:
for node in self.__peer_nodes:
try:
url = f"http://{node}/broadcast-transaction"
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 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["timestamp"])
self.__chain.append(converted_block)
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.signature ==incoming_tx["signature"] and opentx.amount == incoming_tx["amount"]:
try:
self.__open_transactions.remove(opentx)
except ValueError:
print("Item was already removed.")
self.save_data()
return True
def mine_block(self):
if self.public_key == None:
return None
last_block = self.__chain[-1]
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, "", MINING_REWARD)
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 = f"http://{node}/broadcast-block"
dict_block = block.__dict__.copy()
dict_block["transactions"] = [tx.__dict__ for tx in dict_block["transactions"]]
try:
response = requests.post(url, json={"block": dict_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 resolve(self):
for node in self.__peer_nodes:
winner_chain = self.chain
replace = False
url = f"http://{node}/chain"
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["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_blockchain(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):
self.__peer_nodes.discard(node)
self.save_data()
def get_peer_nodes(self):
return list(self.__peer_nodes)