Time out incoming HTLCs when we reach cltv_expiry (+ test)
authorMatt Corallo <git@bluematt.me>
Thu, 9 Jan 2020 19:09:25 +0000 (14:09 -0500)
committerMatt Corallo <git@bluematt.me>
Fri, 24 Apr 2020 18:28:50 +0000 (14:28 -0400)
We only do this for incoming HTLCs directly as we rely on channel
closure and HTLC-Timeout broadcast to fail any HTLCs which we
relayed onwards where our next-hop doesn't update_fail in time.

lightning/src/ln/channelmanager.rs
lightning/src/ln/functional_test_utils.rs
lightning/src/ln/functional_tests.rs
lightning/src/util/events.rs

index 0acc59df62e2ff33d1311bbf9be1e87846b70f39..b616567073eb9741f1e0ebbfaa2385440f9be954 100644 (file)
@@ -28,7 +28,7 @@ use secp256k1;
 use chain::chaininterface::{BroadcasterInterface,ChainListener,FeeEstimator};
 use chain::transaction::OutPoint;
 use ln::channel::{Channel, ChannelError};
-use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, ManyChannelMonitor, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY};
+use ln::channelmonitor::{ChannelMonitor, ChannelMonitorUpdate, ChannelMonitorUpdateErr, ManyChannelMonitor, CLTV_CLAIM_BUFFER, LATENCY_GRACE_PERIOD_BLOCKS, ANTI_REORG_DELAY, HTLC_FAIL_BACK_BUFFER};
 use ln::features::{InitFeatures, NodeFeatures};
 use ln::router::{Route, RouteHop};
 use ln::msgs;
@@ -76,6 +76,7 @@ enum PendingHTLCRouting {
        },
        Receive {
                payment_data: Option<msgs::FinalOnionHopData>,
+               incoming_cltv_expiry: u32, // Used to track when we should expire pending HTLCs that go unclaimed
        },
 }
 
@@ -129,6 +130,7 @@ struct ClaimableHTLC {
        /// payment_secret which prevents path-probing attacks and can associate different HTLCs which
        /// are part of the same payment.
        payment_data: Option<msgs::FinalOnionHopData>,
+       cltv_expiry: u32,
 }
 
 /// Tracks the inbound corresponding to an outbound HTLC
@@ -296,8 +298,6 @@ pub(super) struct ChannelHolder<ChanSigner: ChannelKeys> {
        /// Note that while this is held in the same mutex as the channels themselves, no consistency
        /// guarantees are made about the channels given here actually existing anymore by the time you
        /// go to read them!
-       /// TODO: We need to time out HTLCs sitting here which are waiting on other AMP HTLCs to
-       /// arrive.
        claimable_htlcs: HashMap<(PaymentHash, Option<PaymentSecret>), Vec<ClaimableHTLC>>,
        /// Messages to send to peers - pushed to in the same lock that they are generated in (except
        /// for broadcast messages, where ordering isn't as strict).
@@ -1063,7 +1063,10 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref> ChannelMan
                                // delay) once they've send us a commitment_signed!
 
                                PendingHTLCStatus::Forward(PendingHTLCInfo {
-                                       routing: PendingHTLCRouting::Receive { payment_data },
+                                       routing: PendingHTLCRouting::Receive {
+                                               payment_data,
+                                               incoming_cltv_expiry: msg.cltv_expiry,
+                                       },
                                        payment_hash: msg.payment_hash.clone(),
                                        incoming_shared_secret: shared_secret,
                                        amt_to_forward: next_hop_data.amt_to_forward,
@@ -1686,7 +1689,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref> ChannelMan
                                        for forward_info in pending_forwards.drain(..) {
                                                match forward_info {
                                                        HTLCForwardInfo::AddHTLC { prev_short_channel_id, prev_htlc_id, forward_info: PendingHTLCInfo {
-                                                                       routing: PendingHTLCRouting::Receive { payment_data },
+                                                                       routing: PendingHTLCRouting::Receive { payment_data, incoming_cltv_expiry },
                                                                        incoming_shared_secret, payment_hash, amt_to_forward, .. }, } => {
                                                                let prev_hop = HTLCPreviousHopData {
                                                                        short_channel_id: prev_short_channel_id,
@@ -1703,6 +1706,7 @@ impl<ChanSigner: ChannelKeys, M: Deref, T: Deref, K: Deref, F: Deref> ChannelMan
                                                                        prev_hop,
                                                                        value: amt_to_forward,
                                                                        payment_data: payment_data.clone(),
+                                                                       cltv_expiry: incoming_cltv_expiry,
                                                                });
                                                                if let &Some(ref data) = &payment_data {
                                                                        for htlc in htlcs.iter() {
@@ -2958,6 +2962,7 @@ impl<ChanSigner: ChannelKeys, M: Deref + Sync + Send, T: Deref + Sync + Send, K:
                log_trace!(self, "Block {} at height {} connected with {} txn matched", header_hash, height, txn_matched.len());
                let _ = self.total_consistency_lock.read().unwrap();
                let mut failed_channels = Vec::new();
+               let mut timed_out_htlcs = Vec::new();
                {
                        let mut channel_lock = self.channel_state.lock().unwrap();
                        let channel_state = &mut *channel_lock;
@@ -3026,10 +3031,35 @@ impl<ChanSigner: ChannelKeys, M: Deref + Sync + Send, T: Deref + Sync + Send, K:
                                }
                                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 }
+                               });
+                               !htlcs.is_empty() // Only retain this entry if htlcs has at least one entry.
+                       });
                }
                for failure in failed_channels.drain(..) {
                        self.finish_force_close_channel(failure);
                }
+
+               for (source, payment_hash, reason) in timed_out_htlcs.drain(..) {
+                       // Call it incorrect_or_unknown_payment_details as the issue, ultimately, is that the
+                       // user failed to provide us a preimage within the cltv_expiry time window.
+                       self.fail_htlc_backwards_internal(self.channel_state.lock().unwrap(), source, &payment_hash, reason);
+               }
                self.latest_block_height.store(height as usize, Ordering::Release);
                *self.last_block_hash.try_lock().expect("block_(dis)connected must not be called in parallel") = header_hash;
                loop {
@@ -3320,9 +3350,10 @@ impl Writeable for PendingHTLCInfo {
                                onion_packet.write(writer)?;
                                short_channel_id.write(writer)?;
                        },
-                       &PendingHTLCRouting::Receive { ref payment_data } => {
+                       &PendingHTLCRouting::Receive { ref payment_data, ref incoming_cltv_expiry } => {
                                1u8.write(writer)?;
                                payment_data.write(writer)?;
+                               incoming_cltv_expiry.write(writer)?;
                        },
                }
                self.incoming_shared_secret.write(writer)?;
@@ -3343,6 +3374,7 @@ impl Readable for PendingHTLCInfo {
                                },
                                1u8 => PendingHTLCRouting::Receive {
                                        payment_data: Readable::read(reader)?,
+                                       incoming_cltv_expiry: Readable::read(reader)?,
                                },
                                _ => return Err(DecodeError::InvalidValue),
                        },
@@ -3415,7 +3447,8 @@ impl_writeable!(HTLCPreviousHopData, 0, {
 impl_writeable!(ClaimableHTLC, 0, {
        prev_hop,
        value,
-       payment_data
+       payment_data,
+       cltv_expiry
 });
 
 impl Writeable for HTLCSource {
index 55f734a32af5e3e2231b888bd63a0da53f480fd5..5fd42079398a10cc34d9955d24d45ea7dfff4d64 100644 (file)
@@ -717,7 +717,7 @@ macro_rules! get_payment_preimage_hash {
        }
 }
 
-macro_rules! expect_pending_htlcs_forwardable {
+macro_rules! expect_pending_htlcs_forwardable_ignore {
        ($node: expr) => {{
                let events = $node.node.get_and_clear_pending_events();
                assert_eq!(events.len(), 1);
@@ -725,6 +725,12 @@ macro_rules! expect_pending_htlcs_forwardable {
                        Event::PendingHTLCsForwardable { .. } => { },
                        _ => panic!("Unexpected event"),
                };
+       }}
+}
+
+macro_rules! expect_pending_htlcs_forwardable {
+       ($node: expr) => {{
+               expect_pending_htlcs_forwardable_ignore!($node);
                $node.node.process_pending_htlc_forwards();
        }}
 }
index 9d8a0bc2465de9f424cd45c90de0d1ef4fcd8512..31c96950af281cb5c834382f870bbaf67c1f9847 100644 (file)
@@ -2320,6 +2320,8 @@ fn claim_htlc_outputs_single_tx() {
                check_added_monitors!(nodes[0], 1);
                nodes[1].block_notifier.block_connected(&Block { header, txdata: vec![revoked_local_txn[0].clone()] }, 200);
                check_added_monitors!(nodes[1], 1);
+               expect_pending_htlcs_forwardable_ignore!(nodes[0]);
+
                connect_blocks(&nodes[1].block_notifier, ANTI_REORG_DELAY - 1, 200, true, header.bitcoin_hash());
 
                let events = nodes[1].node.get_and_clear_pending_events();
@@ -3653,6 +3655,60 @@ fn test_drop_messages_peer_disconnect_dual_htlc() {
        claim_payment(&nodes[0], &[&nodes[1]], payment_preimage_2, 1_000_000);
 }
 
+#[test]
+fn test_htlc_timeout() {
+       // If the user fails to claim/fail an HTLC within the HTLC CLTV timeout we fail it for them
+       // to avoid our counterparty failing the channel.
+       let chanmon_cfgs = create_chanmon_cfgs(2);
+       let node_cfgs = create_node_cfgs(2, &chanmon_cfgs);
+       let node_chanmgrs = create_node_chanmgrs(2, &node_cfgs, &[None, None]);
+       let nodes = create_network(2, &node_cfgs, &node_chanmgrs);
+
+       create_announced_chan_between_nodes(&nodes, 0, 1, InitFeatures::supported(), InitFeatures::supported());
+       let (_, our_payment_hash) = route_payment(&nodes[0], &[&nodes[1]], 100000);
+
+       let mut header = BlockHeader { version: 0x20000000, prev_blockhash: Default::default(), merkle_root: Default::default(), time: 42, bits: 42, nonce: 42 };
+       nodes[0].block_notifier.block_connected_checked(&header, 101, &[], &[]);
+       nodes[1].block_notifier.block_connected_checked(&header, 101, &[], &[]);
+       for i in 102..TEST_FINAL_CLTV + 100 + 1 - CLTV_CLAIM_BUFFER - LATENCY_GRACE_PERIOD_BLOCKS {
+               header.prev_blockhash = header.bitcoin_hash();
+               nodes[0].block_notifier.block_connected_checked(&header, i, &[], &[]);
+               nodes[1].block_notifier.block_connected_checked(&header, i, &[], &[]);
+       }
+
+       expect_pending_htlcs_forwardable!(nodes[1]);
+
+       check_added_monitors!(nodes[1], 1);
+       let htlc_timeout_updates = get_htlc_update_msgs!(nodes[1], nodes[0].node.get_our_node_id());
+       assert!(htlc_timeout_updates.update_add_htlcs.is_empty());
+       assert_eq!(htlc_timeout_updates.update_fail_htlcs.len(), 1);
+       assert!(htlc_timeout_updates.update_fail_malformed_htlcs.is_empty());
+       assert!(htlc_timeout_updates.update_fee.is_none());
+
+       nodes[0].node.handle_update_fail_htlc(&nodes[1].node.get_our_node_id(), &htlc_timeout_updates.update_fail_htlcs[0]);
+       commitment_signed_dance!(nodes[0], nodes[1], htlc_timeout_updates.commitment_signed, false);
+       let events = nodes[0].node.get_and_clear_pending_events();
+       match &events[0] {
+               &Event::PaymentFailed { payment_hash, rejected_by_dest, error_code, ref error_data } => {
+                       assert_eq!(payment_hash, our_payment_hash);
+                       assert!(rejected_by_dest);
+                       assert_eq!(error_code.unwrap(), 0x4000 | 15);
+                       // 100_000 msat as u64, followed by a height of 123 as u32
+                       assert_eq!(&error_data.as_ref().unwrap()[..], &[
+                               ((100_000u64 >> 7*8) & 0xff) as u8,
+                               ((100_000u64 >> 6*8) & 0xff) as u8,
+                               ((100_000u64 >> 5*8) & 0xff) as u8,
+                               ((100_000u64 >> 4*8) & 0xff) as u8,
+                               ((100_000u64 >> 3*8) & 0xff) as u8,
+                               ((100_000u64 >> 2*8) & 0xff) as u8,
+                               ((100_000u64 >> 1*8) & 0xff) as u8,
+                               ((100_000u64 >> 0*8) & 0xff) as u8,
+                               0, 0, 0, 123]);
+               },
+               _ => panic!("Unexpected event"),
+       }
+}
+
 #[test]
 fn test_invalid_channel_announcement() {
        //Test BOLT 7 channel_announcement msg requirement for final node, gather data to build customed channel_announcement msgs
@@ -7140,6 +7196,8 @@ fn test_bump_penalty_txn_on_revoked_htlcs() {
 
        // Broadcast set of revoked txn on A
        let header_128 = connect_blocks(&nodes[0].block_notifier, 128, 0, true, header.bitcoin_hash());
+       expect_pending_htlcs_forwardable_ignore!(nodes[0]);
+
        let header_129 = BlockHeader { version: 0x20000000, prev_blockhash: header_128, merkle_root: Default::default(), time: 42, bits: 42, nonce: 42 };
        nodes[0].block_notifier.block_connected(&Block { header: header_129, txdata: vec![revoked_local_txn[0].clone(), revoked_htlc_txn[0].clone(), revoked_htlc_txn[1].clone()] }, 129);
        let first;
@@ -7472,6 +7530,8 @@ fn test_bump_txn_sanitize_tracking_maps() {
 
        // Broadcast set of revoked txn on A
        let header_128 = connect_blocks(&nodes[0].block_notifier, 128, 0,  false, Default::default());
+       expect_pending_htlcs_forwardable_ignore!(nodes[0]);
+
        let header_129 = BlockHeader { version: 0x20000000, prev_blockhash: header_128, merkle_root: Default::default(), time: 42, bits: 42, nonce: 42 };
        nodes[0].block_notifier.block_connected(&Block { header: header_129, txdata: vec![revoked_local_txn[0].clone()] }, 129);
        check_closed_broadcast!(nodes[0], false);
index 8f34605675c4ee2992a9f045bc8b49d19e9ffd81..ca6355af001e5eb7d05a96a7ffa22548c9340d87 100644 (file)
@@ -55,6 +55,9 @@ pub enum Event {
        /// ChannelManager::fail_htlc_backwards to free up resources for this HTLC.
        /// The amount paid should be considered 'incorrect' when it is less than or more than twice
        /// the amount expected.
+       /// If you fail to call either ChannelManager::claim_funds or
+       /// ChannelManager::fail_htlc_backwards within the HTLC's timeout, the HTLC will be
+       /// automatically failed.
        PaymentReceived {
                /// The hash for which the preimage should be handed to the ChannelManager.
                payment_hash: PaymentHash,