pallectrum/electrum/plugins/cosigner_pool/qt.py

#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2014 Thomas Voegtlin
#
# Permission is hereby granted, free of charge, to any person
# obtaining a copy of this software and associated documentation files
# (the "Software"), to deal in the Software without restriction,
# including without limitation the rights to use, copy, modify, merge,
# publish, distribute, sublicense, and/or sell copies of the Software,
# and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.

import time
from xmlrpc.client import ServerProxy
from typing import TYPE_CHECKING, Union, List, Tuple, Dict
import ssl

from PyQt5.QtCore import QObject, pyqtSignal
from PyQt5.QtWidgets import QPushButton
import certifi

from electrum import util, keystore, ecc, crypto
from electrum import transaction
from electrum.transaction import Transaction, PartialTransaction, tx_from_any, SerializationError
from electrum.bip32 import BIP32Node
from electrum.plugin import BasePlugin, hook
from electrum.i18n import _
from electrum.wallet import Multisig_Wallet, Abstract_Wallet
from electrum.util import bfh
from electrum.logging import Logger

from electrum.gui.qt.transaction_dialog import show_transaction, TxDialog
from electrum.gui.qt.util import WaitingDialog

if TYPE_CHECKING:
    from electrum.gui.qt import ElectrumGui
    from electrum.gui.qt.main_window import ElectrumWindow


ca_path = certifi.where()
ssl_context = ssl.create_default_context(purpose=ssl.Purpose.SERVER_AUTH, cafile=ca_path)
server = ServerProxy('https://cosigner.electrum.org/', allow_none=True, context=ssl_context)


class Listener(util.DaemonThread):

    def __init__(self, cw: 'CosignerWallet'):
        util.DaemonThread.__init__(self)
        self.daemon = True
        self.cw = cw
        self.received = set()
        self.keyhashes = []

    def set_keyhashes(self, keyhashes):
        self.keyhashes = keyhashes

    def clear(self, keyhash):
        server.delete(keyhash)
        self.received.remove(keyhash)

    def run(self):
        while self.is_running():
            if not self.keyhashes:
                time.sleep(2)
                continue
            for keyhash in self.keyhashes:
                if keyhash in self.received:
                    continue
                try:
                    message = server.get(keyhash)
                except Exception as e:
                    self.logger.info(f"cannot contact cosigner pool. exc: {e!r}")
                    time.sleep(30)
                    continue
                if message:
                    self.received.add(keyhash)
                    self.logger.info(f"received message for {keyhash}")
                    self.cw.obj.cosigner_receive_signal.emit(
                        keyhash, message)
            # poll every 30 seconds
            time.sleep(30)


class QReceiveSignalObject(QObject):
    cosigner_receive_signal = pyqtSignal(object, object)


class Plugin(BasePlugin):

    def __init__(self, parent, config, name):
        BasePlugin.__init__(self, parent, config, name)
        self._init_qt_received = False
        self.cosigner_wallets = {}  # type: Dict[Abstract_Wallet, CosignerWallet]

    @hook
    def init_qt(self, gui: 'ElectrumGui'):
        if self._init_qt_received:  # only need/want the first signal
            return
        self._init_qt_received = True
        for window in gui.windows:
            self.load_wallet(window.wallet, window)

    @hook
    def load_wallet(self, wallet: 'Abstract_Wallet', window: 'ElectrumWindow'):
        if type(wallet) != Multisig_Wallet:
            return
        self.cosigner_wallets[wallet] = CosignerWallet(wallet, window)

    @hook
    def on_close_window(self, window):
        wallet = window.wallet
        if cw := self.cosigner_wallets.get(wallet):
            cw.close()
            self.cosigner_wallets.pop(wallet)

    def is_available(self):
        return True

    @hook
    def transaction_dialog(self, d: 'TxDialog'):
        if cw := self.cosigner_wallets.get(d.wallet):
            cw.hook_transaction_dialog(d)

    @hook
    def transaction_dialog_update(self, d: 'TxDialog'):
        if cw := self.cosigner_wallets.get(d.wallet):
            cw.hook_transaction_dialog_update(d)


class CosignerWallet(Logger):
    # one for each open window

    def __init__(self, wallet: 'Multisig_Wallet', window: 'ElectrumWindow'):
        assert isinstance(wallet, Multisig_Wallet)
        self.wallet = wallet
        self.window = window
        Logger.__init__(self)
        self.obj = QReceiveSignalObject()
        self.obj.cosigner_receive_signal.connect(self.on_receive)

        self.keys = []  # type: List[Tuple[str, str]]
        self.cosigner_list = []  # type: List[Tuple[str, bytes, str]]
        for key, keystore in wallet.keystores.items():
            xpub = keystore.get_master_public_key()  # type: str
            pubkey = BIP32Node.from_xkey(xpub).eckey.get_public_key_bytes(compressed=True)
            _hash = crypto.sha256d(pubkey).hex()
            if not keystore.is_watching_only():
                self.keys.append((key, _hash))
            else:
                self.cosigner_list.append((xpub, pubkey, _hash))

        self.logger.info("starting listener")
        self.listener = Listener(self)
        self.listener.start()
        self.listener.set_keyhashes([t[1] for t in self.keys])

    def diagnostic_name(self):
        return self.wallet.diagnostic_name()

    def close(self):
        self.logger.info("shutting down listener")
        self.listener.stop()
        self.listener = None

    def hook_transaction_dialog(self, d: 'TxDialog'):
        d.cosigner_send_button = b = QPushButton(_("Send to cosigner"))
        b.clicked.connect(lambda: self.do_send(d.tx))
        d.buttons.insert(0, b)
        b.setVisible(False)

    def hook_transaction_dialog_update(self, d: 'TxDialog'):
        assert self.wallet == d.wallet
        if d.tx.is_complete() or d.wallet.can_sign(d.tx):
            d.cosigner_send_button.setVisible(False)
            return
        for xpub, K, _hash in self.cosigner_list:
            if self.cosigner_can_sign(d.tx, xpub):
                d.cosigner_send_button.setVisible(True)
                break
        else:
            d.cosigner_send_button.setVisible(False)

    def cosigner_can_sign(self, tx: Transaction, cosigner_xpub: str) -> bool:
        # TODO implement this properly:
        #      should return True iff cosigner (with given xpub) can sign and has not yet signed.
        #      note that tx could also be unrelated from wallet?... (not ismine inputs)
        return True

    def do_send(self, tx: Union[Transaction, PartialTransaction]):
        def on_success(result):
            self.window.show_message(_("Your transaction was sent to the cosigning pool.") + '\n' +
                                _("Open your cosigner wallet to retrieve it."))
        def on_failure(exc_info):
            e = exc_info[1]
            try: self.logger.error("on_failure", exc_info=exc_info)
            except OSError: pass
            self.window.show_error(_("Failed to send transaction to cosigning pool") + ':\n' + repr(e))

        buffer = []
        # construct messages
        for xpub, K, _hash in self.cosigner_list:
            if not self.cosigner_can_sign(tx, xpub):
                continue
            raw_tx_bytes = tx.serialize_as_bytes()
            public_key = ecc.ECPubkey(K)
            message = public_key.encrypt_message(raw_tx_bytes).decode('ascii')
            buffer.append((_hash, message))
        if not buffer:
            return

        # send messages
        # note: we send all messages sequentially on the same thread
        def send_messages_task():
            for _hash, message in buffer:
                server.put(_hash, message)
        msg = _('Sending transaction to cosigning pool...')
        WaitingDialog(self.window, msg, send_messages_task, on_success, on_failure)

    def on_receive(self, keyhash, message):
        self.logger.info(f"signal arrived for {keyhash}")
        for key, _hash in self.keys:
            if _hash == keyhash:
                break
        else:
            self.logger.info("keyhash not found")
            return

        window = self.window
        wallet = self.wallet
        if isinstance(wallet.keystore, keystore.Hardware_KeyStore):
            window.show_warning(_('An encrypted transaction was retrieved from cosigning pool.') + '\n' +
                                _('However, hardware wallets do not support message decryption, '
                                  'which makes them not compatible with the current design of cosigner pool.'))
            return
        elif wallet.has_keystore_encryption():
            password = window.password_dialog(_('An encrypted transaction was retrieved from cosigning pool.') + '\n' +
                                              _('Please enter your password to decrypt it.'))
            if not password:
                return
        else:
            password = None
            if not window.question(_("An encrypted transaction was retrieved from cosigning pool.") + '\n' +
                                   _("Do you want to open it now?")):
                return

        xprv = wallet.keystore.get_master_private_key(password)
        if not xprv:
            return
        try:
            privkey = BIP32Node.from_xkey(xprv).eckey
            message = privkey.decrypt_message(message)
        except Exception as e:
            self.logger.exception('')
            window.show_error(_('Error decrypting message') + ':\n' + repr(e))
            return

        self.listener.clear(keyhash)
        try:
            tx = tx_from_any(message)
        except SerializationError as e:
            window.show_error(_("Electrum was unable to deserialize the transaction:") + "\n" + str(e))
            return
        show_transaction(tx, parent=window, prompt_if_unsaved=True)