def get_dust_return_pubkey(source, provided_pubkeys, encoding):
"""Return the pubkey to which dust from data outputs will be sent.
This pubkey is used in multi-sig data outputs (as the only real pubkey) to
make those the outputs spendable. It is derived from the source address, so
that the dust is spendable by the creator of the transaction.
"""
# Get hex dust return pubkey.
if script.is_multisig(source):
a, self_pubkeys, b = script.extract_array(backend.multisig_pubkeyhashes_to_pubkeys(source, provided_pubkeys))
dust_return_pubkey_hex = self_pubkeys[0]
else:
dust_return_pubkey_hex = backend.pubkeyhash_to_pubkey(source, provided_pubkeys)
# Convert hex public key into the (binary) dust return pubkey.
try:
dust_return_pubkey = binascii.unhexlify(dust_return_pubkey_hex)
except binascii.Error:
raise script.InputError('Invalid private key.')
return dust_return_pubkey
def construct (db, tx_info, encoding='auto',
fee_per_kb=config.DEFAULT_FEE_PER_KB,
regular_dust_size=config.DEFAULT_REGULAR_DUST_SIZE,
multisig_dust_size=config.DEFAULT_MULTISIG_DUST_SIZE,
op_return_value=config.DEFAULT_OP_RETURN_VALUE,
exact_fee=None, fee_provided=0, provided_pubkeys=None,
allow_unconfirmed_inputs=False):
(source, destination_outputs, data) = tx_info
# Sanity checks.
if exact_fee and not isinstance(exact_fee, int):
raise exceptions.TransactionError('Exact fees must be in satoshis.')
if not isinstance(fee_provided, int):
raise exceptions.TransactionError('Fee provided must be in satoshis.')
'''Destinations'''
# Destination outputs.
# Replace multi‐sig addresses with multi‐sig pubkeys. Check that the
# destination output isn’t a dust output. Set null values to dust size.
destination_outputs_new = []
for (address, value) in destination_outputs:
# Value.
if script.is_multisig(address):
dust_size = multisig_dust_size
else:
dust_size = regular_dust_size
if value == None:
value = dust_size
elif value < dust_size:
raise exceptions.TransactionError('Destination output is dust.')
# Address.
script.validate(address)
if script.is_multisig(address):
destination_outputs_new.append((backend.multisig_pubkeyhashes_to_pubkeys(address, provided_pubkeys), value))
else:
destination_outputs_new.append((address, value))
destination_outputs = destination_outputs_new
destination_shell_out = sum([value for address, value in destination_outputs])
'''Data'''
# Data encoding methods (choose and validate).
if data:
if encoding == 'auto':
if len(data) + len(config.PREFIX) <= config.OP_RETURN_MAX_SIZE:
encoding = 'opreturn'
else:
encoding = 'multisig'
elif encoding not in ('pubkeyhash', 'multisig', 'opreturn'):
raise exceptions.TransactionError('Unknown encoding‐scheme.')
# Divide data into chunks.
if data:
if encoding == 'pubkeyhash':
# Prefix is also a suffix here.
chunk_size = 20 - 1 - 8
elif encoding == 'multisig':
# Two pubkeys, minus length byte, minus prefix, minus two nonces,
# minus two sign bytes.
chunk_size = (33 * 2) - 1 - 8 - 2 - 2
elif encoding == 'opreturn':
chunk_size = config.OP_RETURN_MAX_SIZE
if len(data) + len(config.PREFIX) > chunk_size:
raise exceptions.TransactionError('One `OP_RETURN` output per transaction.')
data_array = list(chunks(data, chunk_size))
else:
data_array = []
# Data outputs.
if data:
if encoding == 'multisig':
data_value = multisig_dust_size
elif encoding == 'opreturn':
data_value = op_return_value
else:
# Pay‐to‐PubKeyHash, e.g.
data_value = regular_dust_size
data_output = (data_array, data_value)
else:
data_output = None
data_shell_out = sum([data_value for data_chunk in data_array])
'''Inputs'''
# Source.
# If public key is necessary for construction of (unsigned)
# transaction, use the public key provided, or find it from the
# blockchain.
if source:
script.validate(source)
if encoding == 'multisig':
dust_return_pubkey = get_dust_return_pubkey(source, provided_pubkeys, encoding)
else:
dust_return_pubkey = None
# Calculate collective size of outputs, for fee calculation.
if encoding == 'multisig':
data_output_size = 81 # 71 for the data
elif encoding == 'opreturn':
data_output_size = 90 # 80 for the data
else:
data_output_size = 25 + 9 # Pay‐to‐PubKeyHash (25 for the data?)
outputs_size = ((25 + 9) * len(destination_outputs)) + (len(data_array) * data_output_size)
# Get inputs.
multisig_inputs = not data
unspent = backend.get_unspent_txouts(source, unconfirmed=allow_unconfirmed_inputs, multisig_inputs=multisig_inputs)
unspent = backend.sort_unspent_txouts(unspent)
logger.debug('Sorted UTXOs: {}'.format([print_coin(coin) for coin in unspent]))
inputs = []
shell_in = 0
change_quantity = 0
sufficient_funds = False
final_fee = fee_per_kb
for coin in unspent:
logger.debug('New input: {}'.format(print_coin(coin)))
inputs.append(coin)
shell_in += round(coin['amount'] * config.UNIT)
# If exact fee is specified, use that. Otherwise, calculate size of tx
# and base fee on that (plus provide a minimum fee for selling SCH).
if exact_fee:
final_fee = exact_fee
else:
size = 181 * len(inputs) + outputs_size + 10
necessary_fee = (int(size / 1000) + 1) * fee_per_kb
final_fee = max(fee_provided, necessary_fee)
assert final_fee >= 1 * fee_per_kb
# Check if good.
shell_out = destination_shell_out + data_shell_out
change_quantity = shell_in - (shell_out + final_fee)
logger.debug('Change quantity: {} SCH'.format(change_quantity / config.UNIT))
# If change is necessary, must not be a dust output.
if change_quantity == 0 or change_quantity >= regular_dust_size:
sufficient_funds = True
break
if not sufficient_funds:
# Approximate needed change, fee by with most recently calculated
# quantities.
shell_out = destination_shell_out + data_shell_out
total_shell_out = shell_out + max(change_quantity, 0) + final_fee
raise exceptions.BalanceError('Insufficient {} at address {}. (Need approximately {} {}.) To spend unconfirmed coins, use the flag `--unconfirmed`. (Unconfirmed coins cannot be spent from multi‐sig addresses.)'.format(config.SCH, source, total_shell_out / config.UNIT, config.SCH))
'''Finish'''
# Change output.
if change_quantity:
if script.is_multisig(source):
change_address = backend.multisig_pubkeyhashes_to_pubkeys(source, provided_pubkeys)
else:
change_address = source
change_output = (change_address, change_quantity)
else:
change_output = None
# Serialise inputs and outputs.
unsigned_tx = serialise(encoding, inputs, destination_outputs,
data_output, change_output,
dust_return_pubkey=dust_return_pubkey)
unsigned_tx_hex = binascii.hexlify(unsigned_tx).decode('utf-8')
'''Sanity Check'''
from shellpartylib.lib import blocks
# Desired transaction info.
(desired_source, desired_destination_outputs, desired_data) = tx_info
desired_source = script.make_canonical(desired_source)
desired_destination = script.make_canonical(desired_destination_outputs[0][0]) if desired_destination_outputs else ''
# NOTE: Include change in destinations for SCH transactions.
# if change_output and not desired_data and desired_destination != config.UNSPENDABLE:
# if desired_destination == '':
# desired_destination = desired_source
# else:
# desired_destination += '-{}'.format(desired_source)
# NOTE
if desired_data == None:
desired_data = b''
# Parsed transaction info.
try:
parsed_source, parsed_destination, x, y, parsed_data = blocks.get_tx_info2(unsigned_tx_hex)
except exceptions.SCHOnlyError:
# Skip SCH‐only transactions.
return unsigned_tx_hex
desired_source = script.make_canonical(desired_source)
# Check desired info against parsed info.
desired = (desired_source, desired_destination, desired_data)
parsed = (parsed_source, parsed_destination, parsed_data)
if desired != parsed:
raise exceptions.TransactionError('Constructed transaction does not parse correctly: {} ≠ {}'.format(desired, parsed))
return unsigned_tx_hex