def txid_to_block_data(txid, bitcoind_proxy, proxy=None):
"""
Given a txid, get its block's data.
Use SPV to verify the information we receive from the (untrusted)
bitcoind host.
@bitcoind_proxy must be a BitcoindConnection (from virtualchain.lib.session)
Return the (block hash, block data, txdata) on success
Return (None, None, None) on error
"""
proxy = get_default_proxy() if proxy is None else proxy
timeout = 1.0
while True:
try:
untrusted_tx_data = bitcoind_proxy.getrawtransaction(txid, 1)
untrusted_block_hash = untrusted_tx_data['blockhash']
untrusted_block_data = bitcoind_proxy.getblock(
untrusted_block_hash)
break
except (OSError, IOError) as ie:
log.exception(ie)
log.error('Network error; retrying...')
timeout = timeout * 2 + random.randint(0, timeout)
continue
except Exception as e:
log.exception(e)
return None, None, None
# first, can we trust this block? is it in the SPV headers?
untrusted_block_header_hex = virtualchain.block_header_to_hex(
untrusted_block_data, untrusted_block_data['previousblockhash'])
block_id = SPVClient.block_header_index(
proxy.spv_headers_path,
('{}00'.format(untrusted_block_header_hex)).decode('hex'))
if block_id < 0:
# bad header
log.error('Block header "{}" is not in the SPV headers ({})'.format(
untrusted_block_header_hex, proxy.spv_headers_path))
return None, None, None
# block header is trusted. Is the transaction data consistent with it?
verified_block_header = virtualchain.block_verify(untrusted_block_data)
if not verified_block_header:
msg = ('Block transaction IDs are not consistent '
'with the Merkle root of the trusted header')
log.error(msg)
return None, None, None
# verify block hash
verified_block_hash = virtualchain.block_header_verify(
untrusted_block_data, untrusted_block_data['previousblockhash'],
untrusted_block_hash)
if not verified_block_hash:
log.error('Block hash is not consistent with block header')
return None, None, None
# we trust the block hash, block data, and txids
block_hash = untrusted_block_hash
block_data = untrusted_block_data
tx_data = untrusted_tx_data
return block_hash, block_data, tx_data
break
except (OSError, IOError), ie:
log.exception(ie)
log.error("Network error; retrying...")
timeout = timeout * 2 + random.randint(0, timeout)
continue
except Exception, e:
log.exception(e)
return (None, None, None)
# first, can we trust this block? is it in the SPV headers?
untrusted_block_header_hex = virtualchain.block_header_to_hex(
untrusted_block_data, untrusted_block_data['previousblockhash'])
block_id = SPVClient.block_header_index(proxy.spv_headers_path,
(untrusted_block_header_hex +
"00").decode('hex'))
if block_id < 0:
# bad header
log.error("Block header '%s' is not in the SPV headers (%s)" %
(untrusted_block_header_hex, proxy.spv_headers_path))
return (None, None, None)
# block header is trusted. Is the transaction data consistent with it?
if not virtualchain.block_verify(untrusted_block_data):
log.error(
"Block transaction IDs are not consistent with the trusted header's Merkle root"
)
return (None, None, None)
# verify block hash