def create_genesis_block(self):
"""
A function to generate genesis block and appends it to
the chain. The block has index 0, previous_hash as 0, and
a valid hash.
"""
genesis_block = Block(0, [], time.time(), "0")
genesis_block.hash = genesis_block.compute_hash()
self.chain.append(genesis_block)
def new_block_mined():
# get the block from request
block_json = request.get_json()
received_block = Block()
# load the data from the request to Block object
if received_block.load_from(block_json):
# this checks if this is a duplicate block we've received. assume we have 3 connected nodes
# (A, B, C). if A mines a block and gives it to B and then B gives it to C, C doesn't know if
# A already has this block or not. This is a quick fix for this problem, we just discard blocks
# that we have received before! hash is a reliable way of ensuring the block is the same as the
# received one
if node.blockchain.get_blockchain_size(
) > 0 and received_block.compute_hash(
) == node.blockchain.get_last_block().compute_hash():
return 'Accepted', 201
# add_block checks the block and makes sure if can be added to our nodes blockchain
if node.blockchain.add_block(received_block):
logger.info('Block %d accepted from the network!' %
received_block.height)
# this flag signals the miner to move to the next block
node.new_block_received = True
# propagate the new block to other known peers
for peer_address in peers:
# quick check not to send back a block to the originator
# as a side note, this is not a reliable way to identify sender,
# but doesn't introduce bugs as we can handle duplicate blocks (see comment a few lines above)
if not request.remote_addr in peer_address:
try:
# call known peers /new_block_mined
url = peer_address + '/new_block_mined'
requests.post(url,
data=request.data,
headers=request.headers)
logger.info('Forwarded to %s' % peer_address)
except:
# could not connect to peer! remove it
peers.remove(peer_address)
logger.info('Could not connect to %s! Peer removed.' %
peer_address)
return 'Accepted', 201
else:
return 'Rejected', 400
else:
# could not load the block information from JSON
logger.info('Block %d rejected by load_from!' % received_block.height)
return 'Rejected', 400
def test_compute_hash(self):
block = self.test_create_block()
b = Block()
b.compute_hash(block)
