purple-electrumwallet/electrum/plugins/labels/labels.py

#!/usr/bin/env python
#
# Electrum - lightweight Bitcoin client
# Copyright (C) 2025 The Electrum Developers
#
# 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 asyncio
import hashlib
import json
from typing import Union, TYPE_CHECKING

import base64

from electrum import util
from electrum.plugin import BasePlugin, hook
from electrum.crypto import aes_encrypt_with_iv, aes_decrypt_with_iv
from electrum.i18n import _
from electrum.util import log_exceptions, ignore_exceptions, make_aiohttp_session
from electrum.network import Network

if TYPE_CHECKING:
    from electrum.wallet import Abstract_Wallet


class ErrorConnectingServer(Exception):
    def __init__(self, reason: Union[str, Exception] = None):
        self.reason = reason

    def __str__(self):
        header = _("Error connecting to {} server").format('Labels')
        reason = self.reason
        if isinstance(reason, BaseException):
            reason = repr(reason)
        return f"{header}: {reason}" if reason else header


class LabelsPlugin(BasePlugin):

    def __init__(self, parent, config, name):
        BasePlugin.__init__(self, parent, config, name)
        self.target_host = 'labels.electrum.org'
        self.wallets = {}

    def encode(self, wallet: 'Abstract_Wallet', msg: str) -> str:
        password, iv, wallet_id = self.wallets[wallet]
        encrypted = aes_encrypt_with_iv(password, iv, msg.encode('utf8'))
        # FIXME: ^ we are reusing the IV between all labels in the wallet, in CBC mode...
        return base64.b64encode(encrypted).decode()

    def decode(self, wallet: 'Abstract_Wallet', message: str) -> str:
        password, iv, wallet_id = self.wallets[wallet]
        decoded = base64.b64decode(message, validate=True)
        decrypted = aes_decrypt_with_iv(password, iv, decoded)
        return decrypted.decode('utf8')

    def get_nonce(self, wallet: 'Abstract_Wallet'):
        # nonce is the nonce to be used with the next change
        nonce = wallet.db.get('wallet_nonce')
        if nonce is None:
            nonce = 1
            self.set_nonce(wallet, nonce)
        return nonce

    def set_nonce(self, wallet: 'Abstract_Wallet', nonce):
        self.logger.info(f"set {wallet.basename()} nonce to {nonce}")
        wallet.db.put("wallet_nonce", nonce)

    @hook
    def set_label(self, wallet: 'Abstract_Wallet', item, label):
        if wallet not in self.wallets:
            return
        if not item:
            return
        if label is None:
            # note: the server should not know whether a label is empty
            #       FIXME but it does! we are reusing the IV with AES-CBC: there is no randomness between labels,
            #       all empty labels in given wallet look the same.
            label = ''
        nonce = self.get_nonce(wallet)
        wallet_id = self.wallets[wallet][2]
        bundle = {
            "walletId": wallet_id,
            "walletNonce": nonce,
            "externalId": self.encode(wallet, item),
            "encryptedLabel": self.encode(wallet, label)
        }
        asyncio.run_coroutine_threadsafe(self.do_post_safe("/label", bundle), wallet.network.asyncio_loop)
        # Caller will write the wallet
        self.set_nonce(wallet, nonce + 1)

    @ignore_exceptions
    @log_exceptions
    async def do_post_safe(self, *args):
        await self.do_post(*args)

    async def do_get(self, url = "/labels"):
        url = 'https://' + self.target_host + url
        network = Network.get_instance()
        proxy = network.proxy if network else None
        async with make_aiohttp_session(proxy) as session:
            async with session.get(url) as result:
                return await result.json()

    async def do_post(self, url = "/labels", data=None):
        url = 'https://' + self.target_host + url
        network = Network.get_instance()
        proxy = network.proxy if network else None
        async with make_aiohttp_session(proxy) as session:
            async with session.post(url, json=data) as result:
                try:
                    return await result.json()
                except Exception as e:
                    raise Exception('Could not decode: ' + await result.text()) from e

    async def push_thread(self, wallet: 'Abstract_Wallet') -> int:
        wallet_data = self.wallets.get(wallet, None)
        if not wallet_data:
            raise Exception('Wallet {} not loaded'.format(wallet))
        wallet_id = wallet_data[2]
        bundle = {"labels": [],
                  "walletId": wallet_id,
                  "walletNonce": self.get_nonce(wallet)}
        for key, value in wallet.get_all_labels().items():
            try:
                encoded_key = self.encode(wallet, key)
                encoded_value = self.encode(wallet, value)
            except Exception:
                self.logger.info(f'cannot encode {repr(key)} {repr(value)}')
                continue
            bundle["labels"].append({'encryptedLabel': encoded_value,
                                     'externalId': encoded_key})
        await self.do_post("/labels", bundle)
        return len(bundle['labels'])

    async def pull_thread(self, wallet: 'Abstract_Wallet', force: bool) -> int:
        wallet_data = self.wallets.get(wallet, None)
        if not wallet_data:
            raise Exception('Wallet {} not loaded'.format(wallet))
        wallet_id = wallet_data[2]
        nonce = 1 if force else self.get_nonce(wallet) - 1
        self.logger.info(f"asking for labels since nonce {nonce}")
        try:
            response = await self.do_get("/labels/since/%d/for/%s" % (nonce, wallet_id))
        except Exception as e:
            raise ErrorConnectingServer(e) from e
        if response["labels"] is None or len(response["labels"]) == 0:
            self.logger.info('no new labels')
            return 0

        self.logger.info(f'received {len(response["labels"])} labels')
        result = {}
        for label in response["labels"]:
            try:
                key = self.decode(wallet, label["externalId"])
                value = self.decode(wallet, label["encryptedLabel"])
            except Exception:
                continue
            try:
                json.dumps(key)
                json.dumps(value)
            except Exception:
                self.logger.info(f'error: no json {key}')
                continue
            if value:
                result[key] = value

        for key, value in result.items():
            wallet._set_label(key, value)

        self.set_nonce(wallet, response["nonce"] + 1)
        util.trigger_callback('labels_received', wallet, result)
        self.on_pulled(wallet)
        return len(result)

    def on_pulled(self, wallet: 'Abstract_Wallet') -> None:
        pass

    @ignore_exceptions
    @log_exceptions
    async def pull_safe_thread(self, wallet: 'Abstract_Wallet', force: bool):
        try:
            await self.pull_thread(wallet, force)
        except ErrorConnectingServer as e:
            self.logger.info(repr(e))

    def pull(self, wallet: 'Abstract_Wallet', force: bool):
        if not wallet.network:
            raise Exception(_('You are offline.'))
        return asyncio.run_coroutine_threadsafe(self.pull_thread(wallet, force), wallet.network.asyncio_loop).result()

    def push(self, wallet: 'Abstract_Wallet'):
        if not wallet.network:
            raise Exception(_('You are offline.'))
        return asyncio.run_coroutine_threadsafe(self.push_thread(wallet), wallet.network.asyncio_loop).result()

    def start_wallet(self, wallet: 'Abstract_Wallet'):
        """Labels have the same level of privacy as the wallet transaction
        history. Since the wallet master public key(s) give access to
        the transaction history, we also use it to encrypt labels.
        """
        if not wallet.network:
            return  # 'offline' mode
        mpk = wallet.get_fingerprint()
        if not mpk:
            return
        mpk = mpk.encode('ascii')
        password = hashlib.sha1(mpk).hexdigest()[:32].encode('ascii')
        iv = hashlib.sha256(password).digest()[:16]
        wallet_id = hashlib.sha256(mpk).hexdigest()
        self.wallets[wallet] = (password, iv, wallet_id)
        nonce = self.get_nonce(wallet)
        self.logger.info(f"wallet {wallet.basename()} nonce is {nonce}")
        # If there is an auth token we can try to actually start syncing
        asyncio.run_coroutine_threadsafe(self.pull_safe_thread(wallet, False), wallet.network.asyncio_loop)

    def stop_wallet(self, wallet):
        self.wallets.pop(wallet, None)