def listen_for_input(self):
waiting_for_input = True
while waiting_for_input:
choice = self.get_user_choice()
if choice == '1':
tx_data = self.get_transaction_value()
recipient, amount = tx_data
signature = self.wallet.sign_transaction(
self.wallet.public_key, recipient, amount)
if self.blockchain.add_transaction(recipient,
self.wallet.public_key,
signature,
amount=amount):
print('Added transaction!')
else:
print('Transaction failed!')
print(self.blockchain.get_open_transactions())
elif choice == '2':
if not self.blockchain.mine_block():
print('Mining failed! Do you have a wallet?')
elif choice == '3':
self.print_blockchain()
elif choice == '4':
if Verification.verify_transactions(
self.blockchain.get_open_transactions(),
self.blockchain.get_balance):
print('All transactions are valid.')
else:
print('There are invalid transactions.')
elif choice == '5':
self.wallet.create_keys()
self.blockchain = Blockchain(self.wallet.public_key)
elif choice == '6':
self.wallet.load_keys()
self.blockchain = Blockchain(self.wallet.public_key)
elif choice == '7':
self.wallet.save_keys()
elif choice == 'q':
waiting_for_input = False
else:
print('Invalid choice! Choose again.')
if not Verification.verify_chain(self.blockchain.chain):
self.print_blockchain()
print('Invalid blockchain!')
break
print('Balance of {}: {:6.2f}'.format(
self.wallet.public_key, self.blockchain.get_balance()))
print()
else:
print('User done!')
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['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.resolve_conflicts = False
self.chain = winner_chain
if replace:
self.__open_transactions = []
self.save_data()
return replace
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 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 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 proof_of_work(self):
"""Generate a proof of work for the open transactions, the hash of the previous block and a random number (which is guessed until it fits)."""
last_block = self.__chain[-1]
last_hash = hash_block(last_block)
proof = 0
# Try different PoW numbers and return the first valid one
while not Verification.valid_proof(self.__open_transactions, last_hash,
proof):
proof += 1
return proof
def add_transaction(self, recipient, sender, signature, amount=1.0):
""" Append a new value as well as the last blockchain value to the blockchain.
Arguments:
:sender: The sender of the funds.
:recipient: The recipient of the funds.
:amount: The amount of funds sent with the transaction (default = 1.0)
"""
if self.hosting_node == None:
return False
transaction = Transaction(sender, recipient, signature, amount)
if Verification.verify_transaction(transaction, self.get_balance):
# add new transaction details to open transactions
self.__open_transactions.append(transaction)
self.save_data()
return True
return False
def add_transaction(self,
recipient,
sender,
signature,
amount=1.0,
is_receiving=False):
""" Append latest value to previous block and push to open_blockchain
Arguments:
sender: sender of coins
recipient: coin recipient
amount: count of coins
"""
# 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 listen_for_input(self):
waiting_for_input = True
# A while loop for the user input interface
# It's a loop that exits once waiting_for_input becomes False or when break is called
while waiting_for_input:
""" Create an infite loop to run the blockchain cli """
# print the user options
print("------------------------------------- ")
print(" ")
print('Please choose an option?')
print(" ")
print('1: Allocate Portfolio Coin Value')
print('2: Mine new block')
print('3: Output the blockchain')
print('4: Check blockchain validity')
print('5: Create Client wallet')
print('6: Load Client wallet')
print('7: Save Client keys')
print('q: Quit')
print(" ")
print("------------------------------------- ")
print(" ")
# save user input
user_choice = self.get_user_choice()
# Create a conditions to service the user input
if user_choice == '1':
tx_data = self.get_transaction_value()
recipient, amount = tx_data # I can destructure or unpack a tuple as such
# create a transaction signature
tx_signature = self.wallet.sign_transaction(
self.wallet.public_key, recipient, amount)
# Add the transaction amount to the blockchain
if self.blockchain.add_transaction(
recipient,
self.wallet.public_key,
tx_signature,
amount=amount
): # add transactiont to open transactions
print('Added transaction!')
else:
print('Transaction failed!')
print("Open Txn: ", self.blockchain.get_open_transactions())
elif user_choice == '2':
try:
if not self.blockchain.mine_block():
print(" ")
print("Mining Failed, You need a Wallet")
print(" ")
except:
print(
"Mining failed please establish a wallet and public key"
)
continue
elif user_choice == '3': # output existing blocks
self.print_blockchain_elements()
elif user_choice == '4':
if Verification.verify_transactions(
self.blockchain.get_open_transactions(),
self.blockchain.get_balance):
print("All transactions are valid")
else:
print("There are invalid transactions")
elif user_choice == '5':
self.wallet.create_keys()
self.blockchain = Blockchain(self.wallet.public_key)
elif user_choice == '6':
self.wallet.load_keys()
self.blockchain = Blockchain(self.wallet.public_key)
elif user_choice == '7':
self.wallet.save_keys()
elif user_choice == 'q':
# This will lead to the loop to exist because it's running condition becomes False
waiting_for_input = False
else:
print('Input was invalid, please pick a value from the list!')
if not Verification.verify_chain(self.blockchain.get_chain()):
self.print_blockchain_elements()
print('Invalid blockchain!')
# Break out of the loop
break
print("-------------------------------------")
print(" ")
print("Node Details:")
print('Account Key: {}, Current Coin Value :{:6.2f}'.format(
self.wallet.public_key, self.blockchain.get_balance()))
print(" ")
else:
print('Session closed')
print('Program secure, Logged Out!')
print(" ")