Add method to note transaction unconfirmed/reorged-out

TheBlueMatt · TheBlueMatt · commit b04720ad9a57 · 2021-04-14T14:15:36.000-04:00
diff --git a/lightning/src/ln/channel.rs b/lightning/src/ln/channel.rs
@@ -377,7 +377,7 @@ pub(super) struct Channel<Signer: Sign> {
 
 	/// The hash of the block in which the funding transaction was included.
 	funding_tx_confirmed_in: Option<BlockHash>,
-	funding_tx_confirmation_height: u64,
+	funding_tx_confirmation_height: u32,
 	short_channel_id: Option<u64>,
 
 	counterparty_dust_limit_satoshis: u64,
@@ -3591,7 +3591,7 @@ impl<Signer: Sign> Channel<Signer> {
 									}
 								}
 							}
-							self.funding_tx_confirmation_height = height as u64;
+							self.funding_tx_confirmation_height = height;
 							self.funding_tx_confirmed_in = Some(*block_hash);
 							self.short_channel_id = match scid_from_parts(height as u64, index_in_block as u64, txo_idx as u64) {
 								Ok(scid) => Some(scid),
@@ -3678,6 +3678,32 @@ impl<Signer: Sign> Channel<Signer> {
 		Ok((None, timed_out_htlcs))
 	}
 
+	/// Indicates the funding transaction is no longer confirmed in the main chain. This may
+	/// force-close the channel, but may also indicate a harmless reorganization of a block or two
+	/// before the channel has reached funding_locked and we can just wait for more blocks.
+	pub fn funding_transaction_unconfirmed(&mut self) -> Result<(), msgs::ErrorMessage> {
+		if self.funding_tx_confirmation_height != 0 {
+			// We handle the funding disconnection by calling update_best_block with a height one
+			// below where our funding was connected, implying a reorg back to conf_height - 1.
+			let reorg_height = self.funding_tx_confirmation_height - 1;
+			// We use the time field to bump the current time we set on channel updates if its
+			// larger. If we don't know that time has moved forward, we can just set it to the last
+			// time we saw and it will be ignored.
+			let best_time = self.update_time_counter;
+			match self.update_best_block(reorg_height, best_time) {
+				Ok((funding_locked, timed_out_htlcs)) => {
+					assert!(funding_locked.is_none(), "We can't generate a funding with 0 confirmations?");
+					assert!(timed_out_htlcs.is_empty(), "We can't have accepted HTLCs with a timeout before our funding confirmation?");
+					Ok(())
+				},
+				Err(e) => Err(e)
+			}
+		} else {
+			// We never learned about the funding confirmation anyway, just ignore
+			Ok(())
+		}
+	}
+
 	// Methods to get unprompted messages to send to the remote end (or where we already returned
 	// something in the handler for the message that prompted this message):
 
diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
@@ -28,7 +28,7 @@ use bitcoin::hashes::hmac::{Hmac, HmacEngine};
 use bitcoin::hashes::sha256::Hash as Sha256;
 use bitcoin::hashes::sha256d::Hash as Sha256dHash;
 use bitcoin::hashes::cmp::fixed_time_eq;
-use bitcoin::hash_types::BlockHash;
+use bitcoin::hash_types::{BlockHash, Txid};
 
 use bitcoin::secp256k1::key::{SecretKey,PublicKey};
 use bitcoin::secp256k1::Secp256k1;
@@ -3353,7 +3353,7 @@ where
 			"Blocks must be disconnected in chain-order - the disconnected block must have the correct height");
 		*self.last_block_hash.write().unwrap() = header.prev_blockhash;
 
-		self.do_chain_event(new_height, |channel| channel.update_best_block(new_height, header.time));
+		self.do_chain_event(Some(new_height), |channel| channel.update_best_block(new_height, header.time));
 	}
 }
 
@@ -3364,8 +3364,11 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
         F::Target: FeeEstimator,
         L::Target: Logger,
 {
+	/// Calls a function which handles an on-chain event (blocks dis/connected, transactions
+	/// un/confirmed, etc) on each channel, handling any resulting errors or messages generated by
+	/// the function.
 	fn do_chain_event<FN: Fn(&mut Channel<Signer>) -> Result<(Option<msgs::FundingLocked>, Vec<(HTLCSource, PaymentHash)>), msgs::ErrorMessage>>
-			(&self, height: u32, f: FN) {
+			(&self, height_opt: Option<u32>, f: FN) {
 		// Note that we MUST NOT end up calling methods on self.chain_monitor here - we're called
 		// during initialization prior to the chain_monitor being fully configured in some cases.
 		// See the docs for `ChannelManagerReadArgs` for more.
@@ -3424,24 +3427,26 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 				true
 			});
 
-			channel_state.claimable_htlcs.retain(|&(ref payment_hash, _), htlcs| {
-				htlcs.retain(|htlc| {
-					// If height is approaching the number of blocks we think it takes us to get
-					// our commitment transaction confirmed before the HTLC expires, plus the
-					// number of blocks we generally consider it to take to do a commitment update,
-					// just give up on it and fail the HTLC.
-					if height >= htlc.cltv_expiry - HTLC_FAIL_BACK_BUFFER {
-						let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec();
-						htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array(height));
-						timed_out_htlcs.push((HTLCSource::PreviousHopData(htlc.prev_hop.clone()), payment_hash.clone(), HTLCFailReason::Reason {
-							failure_code: 0x4000 | 15,
-							data: htlc_msat_height_data
-						}));
-						false
-					} else { true }
+			if let Some(height) = height_opt {
+				channel_state.claimable_htlcs.retain(|&(ref payment_hash, _), htlcs| {
+					htlcs.retain(|htlc| {
+						// If height is approaching the number of blocks we think it takes us to get
+						// our commitment transaction confirmed before the HTLC expires, plus the
+						// number of blocks we generally consider it to take to do a commitment update,
+						// just give up on it and fail the HTLC.
+						if height >= htlc.cltv_expiry - HTLC_FAIL_BACK_BUFFER {
+							let mut htlc_msat_height_data = byte_utils::be64_to_array(htlc.value).to_vec();
+							htlc_msat_height_data.extend_from_slice(&byte_utils::be32_to_array(height));
+							timed_out_htlcs.push((HTLCSource::PreviousHopData(htlc.prev_hop.clone()), payment_hash.clone(), HTLCFailReason::Reason {
+								failure_code: 0x4000 | 15,
+								data: htlc_msat_height_data
+							}));
+							false
+						} else { true }
+					});
+					!htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
 				});
-				!htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
-			});
+			}
 		}
 
 		self.handle_init_event_channel_failures(failed_channels);
@@ -3477,7 +3482,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 		log_trace!(self.logger, "{} transactions included in block {} at height {} provided", txdata.len(), block_hash, height);
 
 		let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
-		self.do_chain_event(height, |channel| channel.transactions_confirmed(&block_hash, height, txdata, &self.logger).map(|a| (a, Vec::new())));
+		self.do_chain_event(Some(height), |channel| channel.transactions_confirmed(&block_hash, height, txdata, &self.logger).map(|a| (a, Vec::new())));
 	}
 
 	/// Updates channel state with the current best blockchain tip. You should attempt to call this
@@ -3506,7 +3511,7 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 		self.latest_block_height.store(height as usize, Ordering::Release);
 		*self.last_block_hash.write().unwrap() = block_hash;
 
-		self.do_chain_event(height, |channel| channel.update_best_block(height, header.time));
+		self.do_chain_event(Some(height), |channel| channel.update_best_block(height, header.time));
 
 		loop {
 			// Update last_node_announcement_serial to be the max of its current value and the
@@ -3522,6 +3527,60 @@ impl<Signer: Sign, M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelMana
 		}
 	}
 
+	/// Gets the set of txids which should be monitored for their confirmation state.
+	///
+	/// If you're providing information about reorganizations via [`transaction_unconfirmed`], this
+	/// is the set of transactions which you may need to call [`transaction_unconfirmed`] for.
+	///
+	/// This may be useful to poll to determine the set of transactions which must be registered
+	/// with an Electrum server or for which an Electrum server needs to be polled to determine
+	/// transaction confirmation state.
+	///
+	/// This may update after any [`transactions_confirmed`] or [`block_connected`] call.
+	///
+	/// Note that this is NOT the set of transactions which must be included in calls to
+	/// [`transactions_confirmed`] if they are confirmed, but a small subset of it.
+	///
+	/// [`transactions_confirmed`]: Self::transactions_confirmed
+	/// [`transaction_unconfirmed`]: Self::transaction_unconfirmed
+	pub fn get_relevant_txids(&self) -> Vec<Txid> {
+		let channel_state = self.channel_state.lock().unwrap();
+		let mut res = Vec::with_capacity(channel_state.short_to_id.len());
+		for chan in channel_state.by_id.values() {
+			if let Some(funding_txo) = chan.get_funding_txo() {
+				res.push(funding_txo.txid);
+			}
+		}
+		res
+	}
+
+	/// Marks a transaction as having been reorganized out of the blockchain.
+	///
+	/// If a transaction is included in [`get_relevant_txids`], and is no longer in the main branch
+	/// of the blockchain, this function should be called to indicate that the transaction should
+	/// be considered reorganized out.
+	///
+	/// Once this is called, the given transaction will no longer appear on [`get_relevant_txids`],
+	/// though this may be called repeatedly for a given transaction without issue.
+	///
+	/// Note that if the transaction is confirmed on the main chain in a different block (indicated
+	/// via a call to [`transactions_confirmed`]), it may re-appear in [`get_relevant_txids`], thus
+	/// be very wary of race-conditions wherein the final state of a transaction indicated via
+	/// these APIs is not the same as its state on the blockchain.
+	///
+	/// [`transactions_confirmed`]: Self::transactions_confirmed
+	/// [`get_relevant_txids`]: Self::get_relevant_txids
+	pub fn transaction_unconfirmed(&self, txid: &Txid) {
+		let _persistence_guard = PersistenceNotifierGuard::new(&self.total_consistency_lock, &self.persistence_notifier);
+		self.do_chain_event(None, |channel| {
+			if let Some(funding_txo) = channel.get_funding_txo() {
+				if funding_txo.txid == *txid {
+					channel.funding_transaction_unconfirmed().map(|_| (None, Vec::new()))
+				} else { Ok((None, Vec::new())) }
+			} else { Ok((None, Vec::new())) }
+		});
+	}
+
 	/// Blocks until ChannelManager needs to be persisted or a timeout is reached. It returns a bool
 	/// indicating whether persistence is necessary. Only one listener on
 	/// `await_persistable_update` or `await_persistable_update_timeout` is guaranteed to be woken
