Python-bitcoinlib Examples

The python-bitcoinlib library allows constructing various objects from bytes. We can use this to more granularly inspect kernel objects that expose their contents as bytes, such as Block (kernel_Block) and TransactionOutput (kernel_TransactionOutput).

Note

The python-bitcoinlib library is unrelated to this project, and information here is provided only on a best-effort basis.

Setup

First, we'll create a ChainstateManager and load the current chain tip:

import pbk
chainman = pbk.load_chainman("/tmp/bitcoin/signet/", pbk.ChainType.SIGNET)
tip = chainman.get_active_chain().block_tree_entries[-1]

Inspecting Block Data

To analyze the block, we can use the python-bitcoinlib CBlock class:

from bitcoin.core import CBlock

block_bytes = bytes(chainman.blocks[tip])
cblock = CBlock.deserialize(block_bytes)

assert tip.block_hash == cblock.GetHash()
print(f"Block {cblock.GetHash()} has {len(cblock.vtx)} transactions and {cblock.GetWeight()} weight")
print(f"The last transaction has witness data: {cblock.vtx[-1].wit.vtxinwit}")

Inspecting TransactionOutput data

from bitcoin.core.script import CScript
from pprint import pprint

undo = chainman.block_spent_outputs[tip]
result = {}
for i, tx in enumerate(undo.transactions):
    result[i] = [CScript(bytes(coin.output.script_pubkey)) for coin in tx.coins]
print(f"Block {tip.height} has transactions spending the following previous outputs:")
pprint(result)