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node.py
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node.py
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from flask import Flask, jsonify, request, send_from_directory
from flask_cors import CORS
from wallet import Wallet
from blockchain import Blockchain
app = Flask(__name__)
CORS(app)
wallet = Wallet()
blockchain = Blockchain(wallet.public_key)
def resp(status_code=200, message='Success', data=None):
"""Helper function to return jsonified response"""
response = { 'message': message }
if data:
response.update(data)
return jsonify(response), status_code
def validate_request_data(data, required_fields=None):
"""Helper function to validates the request data.
returns None if data is valid, i.e., data is present and
required_fields, if any, are also present.
Otherwise, returns a jsonified response object
with 400 status and an error message.
Arguments:
:data: Dictionary of request parameters to validate
:required_fields: List of fields that are required to be present
"""
if not data:
return resp(400, 'No data found')
if required_fields:
if not all(field in data for field in required_fields):
return resp(400, 'Required data is misssing')
return None
@app.route('/', methods=['GET'])
def get_ui():
return send_from_directory('ui', 'node.html')
@app.route('/network', methods=['GET'])
def get_network_ui():
return send_from_directory('ui', 'network.html')
@app.route('/transactions', methods=['GET'])
def get_transactions():
transactions = blockchain.get_open_transactions()
dict_transactions = [tx.to_dict() for tx in transactions]
return jsonify(dict_transactions), 200
@app.route('/transaction', methods=['POST'])
def add_transaction():
"""TODO: Validate input parameters"""
if wallet.public_key == None:
return resp(400, 'No wallet set up')
data = request.get_json()
required_fields = ['recipient', 'amount']
invalid_data_response = validate_request_data(data, required_fields)
if invalid_data_response:
return invalid_data_response
recipient = data['recipient']
amount = data['amount']
signature = wallet.sign_transactions(wallet.public_key, recipient, amount)
success = blockchain.add_transaction(sender=wallet.public_key, recipient=recipient, amount=amount, signature=signature)
if success:
return resp(201, 'Transaction added successfully.', {
'transaction': blockchain.get_open_transactions()[-1].to_dict(),
'balance': blockchain.get_balance()
})
else:
return resp(500, 'Failed to create a transaction')
@app.route('/broadcast-transaction', methods=['POST'])
def broadcast_transaction():
"""Receive broadcast of newly added transactions from other nodes"""
data = request.get_json()
required_fields = ['sender', 'recipient', 'amount', 'signature']
invalid_data_response = validate_request_data(data, required_fields)
if invalid_data_response:
return invalid_data_response
success = blockchain.add_transaction(sender=data['sender'], recipient=data['recipient'], amount=data['amount'], signature=data['signature'], is_receiving=True)
if success:
return resp(201, 'Transaction added successfully.', {
'transaction': blockchain.get_open_transactions()[-1].to_dict(),
'balance': blockchain.get_balance()
})
else:
return resp(500, 'Failed to create a transaction.')
@app.route('/broadcast-block', methods=['POST'])
def broadcast_block():
"""Receive broadcast of newly mined blocks from other nodes"""
data = request.get_json()
required_fields = ['block']
invalid_data_response = validate_request_data(data, required_fields)
if invalid_data_response:
return invalid_data_response
block = data['block']
last_local_block_index = blockchain.get_last_block()['index']
if block['index'] == last_local_block_index + 1:
if blockchain.add_block(block):
return resp(201, 'Block added successfully.')
else:
return resp(409, 'Block seems invalid.') # Invalid data (conflict)
elif block['index'] > last_local_block_index:
# TODO: Our chain is shorter.. We need to fix it!
blockchain.resolve_conflicts = True
return resp(200, 'Bockchain seems to differ from local blockchain.') # Not an error (Current node needs to fix the issue)
else:
# Our blockchain is more recent (has longer chain)
return resp(409, 'Bockchain seems to be shorter. Block not added.') # Invalid data (conflict)
@app.route('/resolve-conflicts', methods=['POST'])
def resolve_conflicts():
replaced = blockchain.resolve()
if replaced:
return resp(200, 'Chain was replaced.')
else:
return resp(200, 'Local chain kept.')
@app.route('/wallet', methods=['POST'])
def create_keys():
wallet.create_keys()
if wallet.save_keys():
global blockchain
blockchain = Blockchain(wallet.public_key)
return resp(201, '', {
'public_key': wallet.public_key,
'private_key': wallet.private_key,
'balance': blockchain.get_balance()
})
else:
return resp(500, 'Failed to save the wallet keys.')
@app.route('/wallet', methods=['GET'])
def load_keys():
if wallet.load_keys():
global blockchain
blockchain = Blockchain(wallet.public_key)
return resp(200, '', {
'public_key': wallet.public_key,
'private_key': wallet.private_key,
'balance': blockchain.get_balance()
})
else:
return resp(500, 'Failed to load the wallet keys.')
@app.route('/balance', methods=['GET'])
def get_balance():
balance = blockchain.get_balance()
if balance != None:
return resp(200, 'Balance fetched successfully.', {
'balance': blockchain.get_balance()
})
else:
return resp(500, 'Failed to load balance.', {
'is_wallet_setup': wallet.public_key != None
})
@app.route('/mine', methods=['POST'])
def mine():
if blockchain.resolve_conflicts:
return resp(409, 'Block not added due to conflicts.')
block = blockchain.mine_block()
if block != None:
return resp(201, 'Mining successful. Block added.', {
'added_block': block.to_dict(),
'balance': blockchain.get_balance()
})
else:
return resp(500, 'Mining failed. Block not added.', {
'is_wallet_setup': wallet.public_key != None
})
@app.route('/chain', methods=['GET'])
def get_chain():
return jsonify(blockchain.get_chain_dict()), 200
@app.route('/nodes', methods=['GET'])
def get_nodes():
return resp(200, '', {
'peer_nodes': blockchain.get_peer_nodes()
})
@app.route('/node', methods=['POST'])
def add_node():
data = request.get_json()
required_fields = ['node']
invalid_data_response = validate_request_data(data, required_fields)
if invalid_data_response:
return invalid_data_response
blockchain.add_peer_node(data['node'])
return resp(201, 'Node added successfully.', {
'peer_nodes': blockchain.get_peer_nodes()
})
@app.route('/node/<node_url>', methods=['DELETE'])
def remove_node(node_url):
if not node_url:
return resp(400, 'No node data found')
blockchain.remove_peer_node(node_url)
return resp(200, 'Node removed successfully.', {
'peer_nodes': blockchain.get_peer_nodes()
})
if __name__ == '__main__':
from argparse import ArgumentParser
parser = ArgumentParser()
parser.add_argument('-p', '--port', type=int, default=4000)
args = parser.parse_args()
app.run(host='127.0.0.1', port=args.port)