189 lines
8.4 KiB
Python
189 lines
8.4 KiB
Python
# -*- coding: utf-8 -*-
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#
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# Electrum - lightweight Bitcoin client
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# Copyright (C) 2018 The Electrum developers
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#
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# Permission is hereby granted, free of charge, to any person
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# obtaining a copy of this software and associated documentation files
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# (the "Software"), to deal in the Software without restriction,
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# including without limitation the rights to use, copy, modify, merge,
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# publish, distribute, sublicense, and/or sell copies of the Software,
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# and to permit persons to whom the Software is furnished to do so,
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# subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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import asyncio
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import threading
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from typing import TYPE_CHECKING, Dict, Set
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import aiorpcx
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from . import bitcoin
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from . import ecc
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from . import constants
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from .util import bh2u, bfh, NetworkJobOnDefaultServer
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from .lnutil import funding_output_script_from_keys, ShortChannelID
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from .verifier import verify_tx_is_in_block, MerkleVerificationFailure
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from .transaction import Transaction
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from .interface import GracefulDisconnect
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from .crypto import sha256d
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from .lnmsg import decode_msg, encode_msg
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if TYPE_CHECKING:
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from .network import Network
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from .lnrouter import ChannelDB
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class LNChannelVerifier(NetworkJobOnDefaultServer):
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""" Verify channel announcements for the Channel DB """
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# FIXME the initial routing sync is bandwidth-heavy, and the electrum server
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# will start throttling us, making it even slower. one option would be to
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# spread it over multiple servers.
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def __init__(self, network: 'Network', channel_db: 'ChannelDB'):
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self.channel_db = channel_db
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self.lock = threading.Lock()
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self.unverified_channel_info = {} # type: Dict[ShortChannelID, dict] # scid -> msg_dict
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# channel announcements that seem to be invalid:
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self.blacklist = set() # type: Set[ShortChannelID]
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NetworkJobOnDefaultServer.__init__(self, network)
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def _reset(self):
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super()._reset()
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self.started_verifying_channel = set() # type: Set[ShortChannelID]
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# TODO make async; and rm self.lock completely
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def add_new_channel_info(self, short_channel_id: ShortChannelID, msg: dict) -> bool:
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if short_channel_id in self.unverified_channel_info:
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return False
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if short_channel_id in self.blacklist:
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return False
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with self.lock:
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self.unverified_channel_info[short_channel_id] = msg
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return True
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async def _run_tasks(self, *, taskgroup):
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await super()._run_tasks(taskgroup=taskgroup)
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async with taskgroup as group:
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await group.spawn(self.main)
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async def main(self):
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while True:
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await self._verify_some_channels()
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await asyncio.sleep(0.1)
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async def _verify_some_channels(self):
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blockchain = self.network.blockchain()
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local_height = blockchain.height()
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with self.lock:
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unverified_channel_info = list(self.unverified_channel_info)
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for short_channel_id in unverified_channel_info:
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if short_channel_id in self.started_verifying_channel:
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continue
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block_height = short_channel_id.block_height
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# only resolve short_channel_id if headers are available.
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if block_height <= 0 or block_height > local_height:
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continue
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header = blockchain.read_header(block_height)
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if header is None:
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if block_height < constants.net.max_checkpoint():
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await self.taskgroup.spawn(self.network.request_chunk(block_height, None, can_return_early=True))
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continue
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self.started_verifying_channel.add(short_channel_id)
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await self.taskgroup.spawn(self.verify_channel(block_height, short_channel_id))
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#self.logger.info(f'requested short_channel_id {bh2u(short_channel_id)}')
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async def verify_channel(self, block_height: int, short_channel_id: ShortChannelID):
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# we are verifying channel announcements as they are from untrusted ln peers.
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# we use electrum servers to do this. however we don't trust electrum servers either...
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try:
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async with self._network_request_semaphore:
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result = await self.network.get_txid_from_txpos(
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block_height, short_channel_id.txpos, True)
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except aiorpcx.jsonrpc.RPCError:
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# the electrum server is complaining about the txpos for given block.
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# it is not clear what to do now, but let's believe the server.
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self._blacklist_short_channel_id(short_channel_id)
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return
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tx_hash = result['tx_hash']
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merkle_branch = result['merkle']
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# we need to wait if header sync/reorg is still ongoing, hence lock:
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async with self.network.bhi_lock:
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header = self.network.blockchain().read_header(block_height)
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try:
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verify_tx_is_in_block(tx_hash, merkle_branch, short_channel_id.txpos, header, block_height)
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except MerkleVerificationFailure as e:
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# the electrum server sent an incorrect proof. blame is on server, not the ln peer
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raise GracefulDisconnect(e) from e
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try:
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async with self._network_request_semaphore:
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raw_tx = await self.network.get_transaction(tx_hash)
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except aiorpcx.jsonrpc.RPCError as e:
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# the electrum server can't find the tx; but it was the
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# one who told us about the txid!! blame is on server
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raise GracefulDisconnect(e) from e
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tx = Transaction(raw_tx)
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try:
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tx.deserialize()
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except Exception:
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# either bug in client, or electrum server is evil.
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# if we connect to a diff server at some point, let's try again.
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self.logger.warning(f"cannot deserialize transaction, skipping {tx_hash}")
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return
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if tx_hash != tx.txid():
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# either bug in client, or electrum server is evil.
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# if we connect to a diff server at some point, let's try again.
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self.logger.info(f"received tx does not match expected txid ({tx_hash} != {tx.txid()})")
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return
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# check funding output
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chan_ann_msg = self.unverified_channel_info[short_channel_id]
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redeem_script = funding_output_script_from_keys(chan_ann_msg['bitcoin_key_1'], chan_ann_msg['bitcoin_key_2'])
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expected_address = bitcoin.redeem_script_to_address('p2wsh', redeem_script)
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try:
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actual_output = tx.outputs()[short_channel_id.output_index]
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except IndexError:
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self._blacklist_short_channel_id(short_channel_id)
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return
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if expected_address != actual_output.address:
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# FIXME what now? best would be to ban the originating ln peer.
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self.logger.info(f"funding output script mismatch for {short_channel_id}")
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self._remove_channel_from_unverified_db(short_channel_id)
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return
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# put channel into channel DB
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self.channel_db.add_verified_channel_info(chan_ann_msg, capacity_sat=actual_output.value)
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self._remove_channel_from_unverified_db(short_channel_id)
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def _remove_channel_from_unverified_db(self, short_channel_id: ShortChannelID):
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with self.lock:
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self.unverified_channel_info.pop(short_channel_id, None)
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self.started_verifying_channel.discard(short_channel_id)
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def _blacklist_short_channel_id(self, short_channel_id: ShortChannelID) -> None:
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self.blacklist.add(short_channel_id)
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with self.lock:
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self.unverified_channel_info.pop(short_channel_id, None)
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def verify_sig_for_channel_update(chan_upd: dict, node_id: bytes) -> bool:
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msg_bytes = chan_upd['raw']
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pre_hash = msg_bytes[2+64:]
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h = sha256d(pre_hash)
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sig = chan_upd['signature']
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if not ecc.verify_signature(node_id, sig, h):
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return False
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return True
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