use crate::chain::chaininterface::{BroadcasterInterface, FeeEstimator, LowerBoundedFeeEstimator};
use crate::chain::transaction::{OutPoint, TransactionData};
use crate::sign::{ChannelDerivationParameters, HTLCDescriptor, SpendableOutputDescriptor, StaticPaymentOutputDescriptor, DelayedPaymentOutputDescriptor, ecdsa::WriteableEcdsaChannelSigner, SignerProvider, EntropySource};
-use crate::chain::onchaintx::{ClaimEvent, OnchainTxHandler};
+use crate::chain::onchaintx::{ClaimEvent, FeerateStrategy, OnchainTxHandler};
use crate::chain::package::{CounterpartyOfferedHTLCOutput, CounterpartyReceivedHTLCOutput, HolderFundingOutput, HolderHTLCOutput, PackageSolvingData, PackageTemplate, RevokedOutput, RevokedHTLCOutput};
use crate::chain::Filter;
use crate::util::logger::{Logger, Record};
use crate::util::ser::{Readable, ReadableArgs, RequiredWrapper, MaybeReadable, UpgradableRequired, Writer, Writeable, U48};
use crate::util::byte_utils;
-use crate::events::{Event, EventHandler};
+use crate::events::{ClosureReason, Event, EventHandler};
use crate::events::bump_transaction::{AnchorDescriptor, BumpTransactionEvent};
+#[allow(unused_imports)]
use crate::prelude::*;
+
use core::{cmp, mem};
use crate::io::{self, Error};
-use core::convert::TryInto;
use core::ops::Deref;
use crate::sync::{Mutex, LockTestExt};
/// A monitor event containing an HTLCUpdate.
HTLCEvent(HTLCUpdate),
+ /// Indicates we broadcasted the channel's latest commitment transaction and thus closed the
+ /// channel. Holds information about the channel and why it was closed.
+ HolderForceClosedWithInfo {
+ /// The reason the channel was closed.
+ reason: ClosureReason,
+ /// The funding outpoint of the channel.
+ outpoint: OutPoint,
+ /// The channel ID of the channel.
+ channel_id: ChannelId,
+ },
+
/// Indicates we broadcasted the channel's latest commitment transaction and thus closed the
/// channel.
HolderForceClosed(OutPoint),
(2, monitor_update_id, required),
(4, channel_id, required),
},
+ (5, HolderForceClosedWithInfo) => {
+ (0, reason, upgradable_required),
+ (2, outpoint, required),
+ (4, channel_id, required),
+ },
;
(2, HTLCEvent),
(4, HolderForceClosed),
}
fn has_reached_confirmation_threshold(&self, best_block: &BestBlock) -> bool {
- best_block.height() >= self.confirmation_threshold()
+ best_block.height >= self.confirmation_threshold()
}
}
/// Ordering of tuple data: (their_per_commitment_point, feerate_per_kw, to_broadcaster_sats,
/// to_countersignatory_sats)
initial_counterparty_commitment_info: Option<(PublicKey, u32, u64, u64)>,
+
+ /// The first block height at which we had no remaining claimable balances.
+ balances_empty_height: Option<u32>,
}
/// Transaction outputs to watch for on-chain spends.
writer.write_all(&(self.pending_monitor_events.iter().filter(|ev| match ev {
MonitorEvent::HTLCEvent(_) => true,
MonitorEvent::HolderForceClosed(_) => true,
+ MonitorEvent::HolderForceClosedWithInfo { .. } => true,
_ => false,
}).count() as u64).to_be_bytes())?;
for event in self.pending_monitor_events.iter() {
upd.write(writer)?;
},
MonitorEvent::HolderForceClosed(_) => 1u8.write(writer)?,
+ // `HolderForceClosedWithInfo` replaced `HolderForceClosed` in v0.0.122. To keep
+ // backwards compatibility, we write a `HolderForceClosed` event along with the
+ // `HolderForceClosedWithInfo` event. This is deduplicated in the reader.
+ MonitorEvent::HolderForceClosedWithInfo { .. } => 1u8.write(writer)?,
_ => {}, // Covered in the TLV writes below
}
}
event.write(writer)?;
}
- self.best_block.block_hash().write(writer)?;
- writer.write_all(&self.best_block.height().to_be_bytes())?;
+ self.best_block.block_hash.write(writer)?;
+ writer.write_all(&self.best_block.height.to_be_bytes())?;
writer.write_all(&(self.onchain_events_awaiting_threshold_conf.len() as u64).to_be_bytes())?;
for ref entry in self.onchain_events_awaiting_threshold_conf.iter() {
self.lockdown_from_offchain.write(writer)?;
self.holder_tx_signed.write(writer)?;
+ // If we have a `HolderForceClosedWithInfo` event, we need to write the `HolderForceClosed` for backwards compatibility.
+ let pending_monitor_events = match self.pending_monitor_events.iter().find(|ev| match ev {
+ MonitorEvent::HolderForceClosedWithInfo { .. } => true,
+ _ => false,
+ }) {
+ Some(MonitorEvent::HolderForceClosedWithInfo { outpoint, .. }) => {
+ let mut pending_monitor_events = self.pending_monitor_events.clone();
+ pending_monitor_events.push(MonitorEvent::HolderForceClosed(*outpoint));
+ pending_monitor_events
+ }
+ _ => self.pending_monitor_events.clone(),
+ };
+
write_tlv_fields!(writer, {
(1, self.funding_spend_confirmed, option),
(3, self.htlcs_resolved_on_chain, required_vec),
- (5, self.pending_monitor_events, required_vec),
+ (5, pending_monitor_events, required_vec),
(7, self.funding_spend_seen, required),
(9, self.counterparty_node_id, option),
(11, self.confirmed_commitment_tx_counterparty_output, option),
(15, self.counterparty_fulfilled_htlcs, required),
(17, self.initial_counterparty_commitment_info, option),
(19, self.channel_id, required),
+ (21, self.balances_empty_height, option),
});
Ok(())
best_block,
counterparty_node_id: Some(counterparty_node_id),
initial_counterparty_commitment_info: None,
+ balances_empty_height: None,
})
}
self.inner.lock().unwrap().counterparty_node_id
}
- /// Used by [`ChannelManager`] deserialization to broadcast the latest holder state if its copy
- /// of the channel state was out-of-date.
- ///
- /// You may also use this to broadcast the latest local commitment transaction, either because
+ /// You may use this to broadcast the latest local commitment transaction, either because
/// a monitor update failed or because we've fallen behind (i.e. we've received proof that our
/// counterparty side knows a revocation secret we gave them that they shouldn't know).
///
- /// Broadcasting these transactions in the second case is UNSAFE, as they allow counterparty
+ /// Broadcasting these transactions in this manner is UNSAFE, as they allow counterparty
/// side to punish you. Nevertheless you may want to broadcast them if counterparty doesn't
/// close channel with their commitment transaction after a substantial amount of time. Best
/// may be to contact the other node operator out-of-band to coordinate other options available
/// to you.
- ///
- /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
- pub fn get_latest_holder_commitment_txn<L: Deref>(&self, logger: &L) -> Vec<Transaction>
- where L::Target: Logger {
+ pub fn broadcast_latest_holder_commitment_txn<B: Deref, F: Deref, L: Deref>(
+ &self, broadcaster: &B, fee_estimator: &F, logger: &L
+ )
+ where
+ B::Target: BroadcasterInterface,
+ F::Target: FeeEstimator,
+ L::Target: Logger
+ {
let mut inner = self.inner.lock().unwrap();
+ let fee_estimator = LowerBoundedFeeEstimator::new(&**fee_estimator);
let logger = WithChannelMonitor::from_impl(logger, &*inner);
- inner.get_latest_holder_commitment_txn(&logger)
+ inner.queue_latest_holder_commitment_txn_for_broadcast(broadcaster, &fee_estimator, &logger);
}
- /// Unsafe test-only version of get_latest_holder_commitment_txn used by our test framework
+ /// Unsafe test-only version of `broadcast_latest_holder_commitment_txn` used by our test framework
/// to bypass HolderCommitmentTransaction state update lockdown after signature and generate
/// revoked commitment transaction.
#[cfg(any(test, feature = "unsafe_revoked_tx_signing"))]
let logger = WithChannelMonitor::from_impl(logger, &*inner);
let current_height = inner.best_block.height;
inner.onchain_tx_handler.rebroadcast_pending_claims(
- current_height, &broadcaster, &fee_estimator, &logger,
+ current_height, FeerateStrategy::HighestOfPreviousOrNew, &broadcaster, &fee_estimator, &logger,
+ );
+ }
+
+ /// Triggers rebroadcasts of pending claims from a force-closed channel after a transaction
+ /// signature generation failure.
+ pub fn signer_unblocked<B: Deref, F: Deref, L: Deref>(
+ &self, broadcaster: B, fee_estimator: F, logger: &L,
+ )
+ where
+ B::Target: BroadcasterInterface,
+ F::Target: FeeEstimator,
+ L::Target: Logger,
+ {
+ let fee_estimator = LowerBoundedFeeEstimator::new(fee_estimator);
+ let mut inner = self.inner.lock().unwrap();
+ let logger = WithChannelMonitor::from_impl(logger, &*inner);
+ let current_height = inner.best_block.height;
+ inner.onchain_tx_handler.rebroadcast_pending_claims(
+ current_height, FeerateStrategy::RetryPrevious, &broadcaster, &fee_estimator, &logger,
);
}
spendable_outputs
}
+ /// Checks if the monitor is fully resolved. Resolved monitor is one that has claimed all of
+ /// its outputs and balances (i.e. [`Self::get_claimable_balances`] returns an empty set).
+ ///
+ /// This function returns true only if [`Self::get_claimable_balances`] has been empty for at least
+ /// 4032 blocks as an additional protection against any bugs resulting in spuriously empty balance sets.
+ pub fn is_fully_resolved<L: Logger>(&self, logger: &L) -> bool {
+ let mut is_all_funds_claimed = self.get_claimable_balances().is_empty();
+ let current_height = self.current_best_block().height;
+ let mut inner = self.inner.lock().unwrap();
+
+ if is_all_funds_claimed {
+ if !inner.funding_spend_seen {
+ debug_assert!(false, "We should see funding spend by the time a monitor clears out");
+ is_all_funds_claimed = false;
+ }
+ }
+
+ const BLOCKS_THRESHOLD: u32 = 4032; // ~four weeks
+ match (inner.balances_empty_height, is_all_funds_claimed) {
+ (Some(balances_empty_height), true) => {
+ // Claimed all funds, check if reached the blocks threshold.
+ return current_height >= balances_empty_height + BLOCKS_THRESHOLD;
+ },
+ (Some(_), false) => {
+ // previously assumed we claimed all funds, but we have new funds to claim.
+ // Should not happen in practice.
+ debug_assert!(false, "Thought we were done claiming funds, but claimable_balances now has entries");
+ log_error!(logger,
+ "WARNING: LDK thought it was done claiming all the available funds in the ChannelMonitor for channel {}, but later decided it had more to claim. This is potentially an important bug in LDK, please report it at https://github.com/lightningdevkit/rust-lightning/issues/new",
+ inner.get_funding_txo().0);
+ inner.balances_empty_height = None;
+ false
+ },
+ (None, true) => {
+ // Claimed all funds but `balances_empty_height` is None. It is set to the
+ // current block height.
+ log_debug!(logger,
+ "ChannelMonitor funded at {} is now fully resolved. It will become archivable in {} blocks",
+ inner.get_funding_txo().0, BLOCKS_THRESHOLD);
+ inner.balances_empty_height = Some(current_height);
+ false
+ },
+ (None, false) => {
+ // Have funds to claim.
+ false
+ },
+ }
+ }
+
#[cfg(test)]
pub fn get_counterparty_payment_script(&self) -> ScriptBuf {
self.inner.lock().unwrap().counterparty_payment_script.clone()
pub fn set_counterparty_payment_script(&self, script: ScriptBuf) {
self.inner.lock().unwrap().counterparty_payment_script = script;
}
+
+ #[cfg(test)]
+ pub fn do_signer_call<F: FnMut(&Signer) -> ()>(&self, mut f: F) {
+ let inner = self.inner.lock().unwrap();
+ f(&inner.onchain_tx_handler.signer);
+ }
}
impl<Signer: WriteableEcdsaChannelSigner> ChannelMonitorImpl<Signer> {
// before considering it "no longer pending" - this matches when we
// provide the ChannelManager an HTLC failure event.
Some(commitment_tx_output_idx) == htlc.transaction_output_index &&
- us.best_block.height() >= event.height + ANTI_REORG_DELAY - 1
+ us.best_block.height >= event.height + ANTI_REORG_DELAY - 1
} else if let OnchainEvent::HTLCSpendConfirmation { commitment_tx_output_idx, .. } = event.event {
// If the HTLC was fulfilled with a preimage, we consider the HTLC
// immediately non-pending, matching when we provide ChannelManager
macro_rules! claim_htlcs {
($commitment_number: expr, $txid: expr) => {
let (htlc_claim_reqs, _) = self.get_counterparty_output_claim_info($commitment_number, $txid, None);
- self.onchain_tx_handler.update_claims_view_from_requests(htlc_claim_reqs, self.best_block.height(), self.best_block.height(), broadcaster, fee_estimator, logger);
+ self.onchain_tx_handler.update_claims_view_from_requests(htlc_claim_reqs, self.best_block.height, self.best_block.height, broadcaster, fee_estimator, logger);
}
}
if let Some(txid) = self.current_counterparty_commitment_txid {
// Assume that the broadcasted commitment transaction confirmed in the current best
// block. Even if not, its a reasonable metric for the bump criteria on the HTLC
// transactions.
- let (claim_reqs, _) = self.get_broadcasted_holder_claims(&holder_commitment_tx, self.best_block.height());
- self.onchain_tx_handler.update_claims_view_from_requests(claim_reqs, self.best_block.height(), self.best_block.height(), broadcaster, fee_estimator, logger);
+ let (claim_reqs, _) = self.get_broadcasted_holder_claims(&holder_commitment_tx, self.best_block.height);
+ self.onchain_tx_handler.update_claims_view_from_requests(claim_reqs, self.best_block.height, self.best_block.height, broadcaster, fee_estimator, logger);
}
}
}
- fn generate_claimable_outpoints_and_watch_outputs(&mut self) -> (Vec<PackageTemplate>, Vec<TransactionOutputs>) {
+ fn generate_claimable_outpoints_and_watch_outputs(&mut self, reason: ClosureReason) -> (Vec<PackageTemplate>, Vec<TransactionOutputs>) {
let funding_outp = HolderFundingOutput::build(
self.funding_redeemscript.clone(),
self.channel_value_satoshis,
let commitment_package = PackageTemplate::build_package(
self.funding_info.0.txid.clone(), self.funding_info.0.index as u32,
PackageSolvingData::HolderFundingOutput(funding_outp),
- self.best_block.height(), self.best_block.height()
+ self.best_block.height, self.best_block.height
);
let mut claimable_outpoints = vec![commitment_package];
- self.pending_monitor_events.push(MonitorEvent::HolderForceClosed(self.funding_info.0));
+ let event = MonitorEvent::HolderForceClosedWithInfo {
+ reason,
+ outpoint: self.funding_info.0,
+ channel_id: self.channel_id,
+ };
+ self.pending_monitor_events.push(event);
+
// Although we aren't signing the transaction directly here, the transaction will be signed
// in the claim that is queued to OnchainTxHandler. We set holder_tx_signed here to reject
// new channel updates.
// assuming it gets confirmed in the next block. Sadly, we have code which considers
// "not yet confirmed" things as discardable, so we cannot do that here.
let (mut new_outpoints, _) = self.get_broadcasted_holder_claims(
- &self.current_holder_commitment_tx, self.best_block.height()
+ &self.current_holder_commitment_tx, self.best_block.height
);
let unsigned_commitment_tx = self.onchain_tx_handler.get_unsigned_holder_commitment_tx();
let new_outputs = self.get_broadcasted_holder_watch_outputs(
F::Target: FeeEstimator,
L::Target: Logger,
{
- let (claimable_outpoints, _) = self.generate_claimable_outpoints_and_watch_outputs();
+ let (claimable_outpoints, _) = self.generate_claimable_outpoints_and_watch_outputs(ClosureReason::HolderForceClosed);
self.onchain_tx_handler.update_claims_view_from_requests(
- claimable_outpoints, self.best_block.height(), self.best_block.height(), broadcaster,
+ claimable_outpoints, self.best_block.height, self.best_block.height, broadcaster,
fee_estimator, logger
);
}
} else if !self.holder_tx_signed {
log_error!(logger, "WARNING: You have a potentially-unsafe holder commitment transaction available to broadcast");
log_error!(logger, " in channel monitor for channel {}!", &self.channel_id());
- log_error!(logger, " Read the docs for ChannelMonitor::get_latest_holder_commitment_txn and take manual action!");
+ log_error!(logger, " Read the docs for ChannelMonitor::broadcast_latest_holder_commitment_txn to take manual action!");
} else {
// If we generated a MonitorEvent::HolderForceClosed, the ChannelManager
// will still give us a ChannelForceClosed event with !should_broadcast, but we
}
}
- fn get_latest_holder_commitment_txn<L: Deref>(
- &mut self, logger: &WithChannelMonitor<L>,
- ) -> Vec<Transaction> where L::Target: Logger {
- log_debug!(logger, "Getting signed latest holder commitment transaction!");
- self.holder_tx_signed = true;
- let commitment_tx = self.onchain_tx_handler.get_fully_signed_holder_tx(&self.funding_redeemscript);
- let txid = commitment_tx.txid();
- let mut holder_transactions = vec![commitment_tx];
- // When anchor outputs are present, the HTLC transactions are only valid once the commitment
- // transaction confirms.
- if self.onchain_tx_handler.channel_type_features().supports_anchors_zero_fee_htlc_tx() {
- return holder_transactions;
- }
- for htlc in self.current_holder_commitment_tx.htlc_outputs.iter() {
- if let Some(vout) = htlc.0.transaction_output_index {
- let preimage = if !htlc.0.offered {
- if let Some(preimage) = self.payment_preimages.get(&htlc.0.payment_hash) { Some(preimage.clone()) } else {
- // We can't build an HTLC-Success transaction without the preimage
- continue;
- }
- } else if htlc.0.cltv_expiry > self.best_block.height() + 1 {
- // Don't broadcast HTLC-Timeout transactions immediately as they don't meet the
- // current locktime requirements on-chain. We will broadcast them in
- // `block_confirmed` when `should_broadcast_holder_commitment_txn` returns true.
- // Note that we add + 1 as transactions are broadcastable when they can be
- // confirmed in the next block.
- continue;
- } else { None };
- if let Some(htlc_tx) = self.onchain_tx_handler.get_fully_signed_htlc_tx(
- &::bitcoin::OutPoint { txid, vout }, &preimage) {
- holder_transactions.push(htlc_tx);
- }
- }
- }
- // We throw away the generated waiting_first_conf data as we aren't (yet) confirmed and we don't actually know what the caller wants to do.
- // The data will be re-generated and tracked in check_spend_holder_transaction if we get a confirmation.
- holder_transactions
- }
-
#[cfg(any(test,feature = "unsafe_revoked_tx_signing"))]
/// Note that this includes possibly-locktimed-in-the-future transactions!
fn unsafe_get_latest_holder_commitment_txn<L: Deref>(
continue;
}
} else { None };
- if let Some(htlc_tx) = self.onchain_tx_handler.get_fully_signed_htlc_tx(
- &::bitcoin::OutPoint { txid, vout }, &preimage) {
- holder_transactions.push(htlc_tx);
+ if let Some(htlc_tx) = self.onchain_tx_handler.get_maybe_signed_htlc_tx(
+ &::bitcoin::OutPoint { txid, vout }, &preimage
+ ) {
+ if htlc_tx.is_fully_signed() {
+ holder_transactions.push(htlc_tx.0);
+ }
}
}
}
{
let block_hash = header.block_hash();
- if height > self.best_block.height() {
+ if height > self.best_block.height {
self.best_block = BestBlock::new(block_hash, height);
log_trace!(logger, "Connecting new block {} at height {}", block_hash, height);
self.block_confirmed(height, block_hash, vec![], vec![], vec![], &broadcaster, &fee_estimator, logger)
- } else if block_hash != self.best_block.block_hash() {
+ } else if block_hash != self.best_block.block_hash {
self.best_block = BestBlock::new(block_hash, height);
log_trace!(logger, "Best block re-orged, replaced with new block {} at height {}", block_hash, height);
self.onchain_events_awaiting_threshold_conf.retain(|ref entry| entry.height <= height);
}
}
- if height > self.best_block.height() {
+ if height > self.best_block.height {
self.best_block = BestBlock::new(block_hash, height);
}
L::Target: Logger,
{
log_trace!(logger, "Processing {} matched transactions for block at height {}.", txn_matched.len(), conf_height);
- debug_assert!(self.best_block.height() >= conf_height);
+ debug_assert!(self.best_block.height >= conf_height);
let should_broadcast = self.should_broadcast_holder_commitment_txn(logger);
if should_broadcast {
- let (mut new_outpoints, mut new_outputs) = self.generate_claimable_outpoints_and_watch_outputs();
+ let (mut new_outpoints, mut new_outputs) = self.generate_claimable_outpoints_and_watch_outputs(ClosureReason::HTLCsTimedOut);
claimable_outpoints.append(&mut new_outpoints);
watch_outputs.append(&mut new_outputs);
}
}
}
- self.onchain_tx_handler.update_claims_view_from_requests(claimable_outpoints, conf_height, self.best_block.height(), broadcaster, fee_estimator, logger);
- self.onchain_tx_handler.update_claims_view_from_matched_txn(&txn_matched, conf_height, conf_hash, self.best_block.height(), broadcaster, fee_estimator, logger);
+ self.onchain_tx_handler.update_claims_view_from_requests(claimable_outpoints, conf_height, self.best_block.height, broadcaster, fee_estimator, logger);
+ self.onchain_tx_handler.update_claims_view_from_matched_txn(&txn_matched, conf_height, conf_hash, self.best_block.height, broadcaster, fee_estimator, logger);
// Determine new outputs to watch by comparing against previously known outputs to watch,
// updating the latter in the process.
// to the source, and if we don't fail the channel we will have to ensure that the next
// updates that peer sends us are update_fails, failing the channel if not. It's probably
// easier to just fail the channel as this case should be rare enough anyway.
- let height = self.best_block.height();
+ let height = self.best_block.height;
macro_rules! scan_commitment {
($htlcs: expr, $holder_tx: expr) => {
for ref htlc in $htlcs {
revocation_pubkey: broadcasted_holder_revokable_script.2,
channel_keys_id: self.channel_keys_id,
channel_value_satoshis: self.channel_value_satoshis,
+ channel_transaction_parameters: Some(self.onchain_tx_handler.channel_transaction_parameters.clone()),
}));
}
}
let mut spendable_txids_confirmed = Some(Vec::new());
let mut counterparty_fulfilled_htlcs = Some(new_hash_map());
let mut initial_counterparty_commitment_info = None;
+ let mut balances_empty_height = None;
let mut channel_id = None;
read_tlv_fields!(reader, {
(1, funding_spend_confirmed, option),
(15, counterparty_fulfilled_htlcs, option),
(17, initial_counterparty_commitment_info, option),
(19, channel_id, option),
+ (21, balances_empty_height, option),
});
+ // `HolderForceClosedWithInfo` replaced `HolderForceClosed` in v0.0.122. If we have both
+ // events, we can remove the `HolderForceClosed` event and just keep the `HolderForceClosedWithInfo`.
+ if let Some(ref mut pending_monitor_events) = pending_monitor_events {
+ if pending_monitor_events.iter().any(|e| matches!(e, MonitorEvent::HolderForceClosed(_))) &&
+ pending_monitor_events.iter().any(|e| matches!(e, MonitorEvent::HolderForceClosedWithInfo { .. }))
+ {
+ pending_monitor_events.retain(|e| !matches!(e, MonitorEvent::HolderForceClosed(_)));
+ }
+ }
+
// Monitors for anchor outputs channels opened in v0.0.116 suffered from a bug in which the
// wrong `counterparty_payment_script` was being tracked. Fix it now on deserialization to
// give them a chance to recognize the spendable output.
chan_utils::get_to_countersignatory_with_anchors_redeemscript(&payment_point).to_v0_p2wsh();
}
- Ok((best_block.block_hash(), ChannelMonitor::from_impl(ChannelMonitorImpl {
+ Ok((best_block.block_hash, ChannelMonitor::from_impl(ChannelMonitorImpl {
latest_update_id,
commitment_transaction_number_obscure_factor,
best_block,
counterparty_node_id,
initial_counterparty_commitment_info,
+ balances_empty_height,
})))
}
}
use crate::sync::{Arc, Mutex};
use crate::io;
use crate::ln::features::ChannelTypeFeatures;
+
+ #[allow(unused_imports)]
use crate::prelude::*;
use std::str::FromStr;