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node.py
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node.py
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"""
Prior Art:
* https://github.com/petertodd/python-bitcoinlib/blob/master/examples/send-addrs-msg.py
* https://github.com/jimmysong/pb-exercises/blob/master/session7/connect.py
"""
import socket
import time
import io
import struct
import random
import datetime
import math
from utils import (
make_nonce,
services_int_to_dict,
encode_command,
int_to_little_endian,
)
from models import (
Message,
Address,
Version,
Verack,
InventoryVector,
InventoryItem,
GetData,
BlockLocator,
GetHeaders,
GetBlocks,
Block,
Headers,
Tx,
TxIn,
TxOut,
)
NETWORK_MAGIC = b'\xf9\xbe\xb4\xd9'
MY_VERSION = 70015 # past bip-31 for ping/pong
NODE_NETWORK = (1 << 0)
NODE_WITNESS = (1 << 3)
USER_AGENT = b"/some-cool-software/"
MY_RELAY = 1 # from version 70001 onwards, fRelay should be appended to version messages (BIP37)
PEER = ("35.187.200.6", 8333)
genesis = int("00000000000000000013424801fbec52484d7211c223beec97f02236a9b6ee03", 16)
# just stores the integer representation of the headers
blocks = [genesis]
def construct_version_msg():
version = MY_VERSION
services = 1024 + 8 + 4 + 2 + 1 # turn 'em all on
timestamp = math.floor(datetime.datetime.utcnow().timestamp())
addr_recv = Address(services=services, ip=0, port=0, time=None)
addr_from = Address(services=services, ip=0, port=0, time=None)
nonce = make_nonce(8)
user_agent = USER_AGENT
# FIXME
start_height = 1
relay = 1
v = Version(version, services, timestamp, addr_recv, addr_from, nonce, user_agent, start_height, relay)
command = encode_command(b'version')
payload = v.serialize()
msg = Message(command, payload)
return msg
def connect():
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
sock.connect(PEER)
return sock
def send_version_msg(sock):
version_msg = construct_version_msg()
sock.send(version_msg.serialize())
def construct_block_locator():
step = 1
height = len(blocks) - 1
hashes = []
while height >= 0:
if len(hashes) >= 10:
step *= 2
header = blocks[height]
hashes.append(header)
height -= step
if not blocks.index(genesis):
blocks.append(genesis)
return BlockLocator(items=hashes)
def construct_block_locator_for_blocks():
step = 1
height = len(blocks) - 1
hashes = []
while height >= 0:
if len(hashes) >= 10:
step *= 2
header = blocks[height]
hashes.append(header)
height -= step
if not blocks.index(genesis):
blocks.append(genesis)
return BlockLocator(items=hashes)
def send_getheaders(sock):
locator = construct_block_locator()
getheaders = GetHeaders(locator)
msg = Message(getheaders.command, getheaders.serialize())
sock.send(msg.serialize())
print('sent getheaders')
def send_getblocks(sock):
locator = construct_block_locator_for_blocks()
getblocks = GetBlocks(locator)
msg = Message(getblocks.command, getblocks.serialize())
sock.send(msg.serialize())
print('sent getblocks')
def handle_version(payload, sock):
version_msg = Version.parse(payload)
print(services_int_to_dict(version_msg.services))
print(version_msg)
def handle_verack(payload, sock):
print('Received Verack')
verack = Verack()
msg = Message(verack.command, verack.serialize())
sock.send(msg.serialize())
# FIXME just here for now ...
send_getheaders(sock)
def handle_inv(payload, sock):
inv_vec = InventoryVector.parse(payload)
getdata = GetData(items=inv_vec.items)
msg = Message(getdata.command, getdata.serialize())
sock.send(msg.serialize())
print("sent getdata")
def update_blocks(block_headers):
for header in block_headers.headers:
# this is naive ...
# we add it to the blocks if prev_block is our current tip
if header.prev_block == blocks[-1]:
blocks.append(header.pow())
else:
break
def handle_headers(payload, sock):
block_headers = Headers.parse(payload)
print(f'{len(block_headers.headers)} new headers')
update_blocks(block_headers)
# after 500 headers, get the blocks
if len(blocks) < 500:
send_getheaders(sock)
else:
items = [InventoryItem(2, int_to_little_endian(hash_, 32)) for hash_ in blocks[:10]]
getdata = GetData(items=items)
msg = Message(getdata.command, getdata.serialize())
sock.send(msg.serialize())
print(f'We now have {len(blocks)} headers')
def handle_block(payload, sock):
block = Block.parse(payload)
print(block)
def handle_tx(payload, sock):
tx = Tx.parse(payload)
print("Received Tx: ", tx)
def handle_msg(msg, sock):
handler_map = {
b'version': handle_version,
b'verack': handle_verack,
b'inv': handle_inv,
b'tx': handle_tx,
b'block': handle_block,
b'headers': handle_headers,
}
handler = handler_map.get(msg.command)
if handler:
payload_stream = io.BytesIO(msg.payload)
handler(payload_stream, sock)
else:
print(f"Unhandled command={msg.command}")
def main_loop(sock):
while True:
try:
msg = Message.parse(sock)
handle_msg(msg, sock)
except RuntimeError as e:
print(e)
continue
print()
def main():
sock = connect()
send_version_msg(sock)
try:
main_loop(sock)
except KeyboardInterrupt:
sock.close()
if __name__ == '__main__':
main()