1 // This file is Copyright its original authors, visible in version control
4 // This file is licensed under the Apache License, Version 2.0 <LICENSE-APACHE
5 // or http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
6 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your option.
7 // You may not use this file except in accordance with one or both of these
10 //! Events are returned from various bits in the library which indicate some action must be taken
13 //! Because we don't have a built-in runtime, it's up to the client to call events at a time in the
14 //! future, as well as generate and broadcast funding transactions handle payment preimages and a
17 use crate::chain::keysinterface::SpendableOutputDescriptor;
19 use crate::ln::chan_utils::{self, ChannelTransactionParameters, HTLCOutputInCommitment};
20 use crate::ln::channelmanager::{InterceptId, PaymentId};
21 use crate::ln::channel::FUNDING_CONF_DEADLINE_BLOCKS;
22 use crate::ln::features::ChannelTypeFeatures;
24 use crate::ln::{PaymentPreimage, PaymentHash, PaymentSecret};
25 use crate::routing::gossip::NetworkUpdate;
26 use crate::util::errors::APIError;
27 use crate::util::ser::{BigSize, FixedLengthReader, Writeable, Writer, MaybeReadable, Readable, RequiredWrapper, UpgradableRequired, WithoutLength};
28 use crate::util::string::UntrustedString;
29 use crate::routing::router::{RouteHop, RouteParameters};
31 use bitcoin::{PackedLockTime, Transaction};
33 use bitcoin::{OutPoint, Txid, TxIn, TxOut, Witness};
34 use bitcoin::blockdata::script::Script;
35 use bitcoin::hashes::Hash;
36 use bitcoin::hashes::sha256::Hash as Sha256;
37 use bitcoin::secp256k1::PublicKey;
39 use bitcoin::secp256k1::{self, Secp256k1};
41 use bitcoin::secp256k1::ecdsa::Signature;
43 use crate::prelude::*;
44 use core::time::Duration;
48 /// Some information provided on receipt of payment depends on whether the payment received is a
49 /// spontaneous payment or a "conventional" lightning payment that's paying an invoice.
50 #[derive(Clone, Debug, PartialEq, Eq)]
51 pub enum PaymentPurpose {
52 /// Information for receiving a payment that we generated an invoice for.
54 /// The preimage to the payment_hash, if the payment hash (and secret) were fetched via
55 /// [`ChannelManager::create_inbound_payment`]. If provided, this can be handed directly to
56 /// [`ChannelManager::claim_funds`].
58 /// [`ChannelManager::create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment
59 /// [`ChannelManager::claim_funds`]: crate::ln::channelmanager::ChannelManager::claim_funds
60 payment_preimage: Option<PaymentPreimage>,
61 /// The "payment secret". This authenticates the sender to the recipient, preventing a
62 /// number of deanonymization attacks during the routing process.
63 /// It is provided here for your reference, however its accuracy is enforced directly by
64 /// [`ChannelManager`] using the values you previously provided to
65 /// [`ChannelManager::create_inbound_payment`] or
66 /// [`ChannelManager::create_inbound_payment_for_hash`].
68 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
69 /// [`ChannelManager::create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment
70 /// [`ChannelManager::create_inbound_payment_for_hash`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
71 payment_secret: PaymentSecret,
73 /// Because this is a spontaneous payment, the payer generated their own preimage rather than us
74 /// (the payee) providing a preimage.
75 SpontaneousPayment(PaymentPreimage),
78 impl_writeable_tlv_based_enum!(PaymentPurpose,
79 (0, InvoicePayment) => {
80 (0, payment_preimage, option),
81 (2, payment_secret, required),
83 (2, SpontaneousPayment)
86 /// When the payment path failure took place and extra details about it. [`PathFailure::OnPath`] may
87 /// contain a [`NetworkUpdate`] that needs to be applied to the [`NetworkGraph`].
89 /// [`NetworkUpdate`]: crate::routing::gossip::NetworkUpdate
90 /// [`NetworkGraph`]: crate::routing::gossip::NetworkGraph
91 #[derive(Clone, Debug, Eq, PartialEq)]
92 pub enum PathFailure {
93 /// We failed to initially send the payment and no HTLC was committed to. Contains the relevant
96 /// The error surfaced from initial send.
99 /// A hop on the path failed to forward our payment.
101 /// If present, this [`NetworkUpdate`] should be applied to the [`NetworkGraph`] so that routing
102 /// decisions can take into account the update.
104 /// [`NetworkUpdate`]: crate::routing::gossip::NetworkUpdate
105 /// [`NetworkGraph`]: crate::routing::gossip::NetworkGraph
106 network_update: Option<NetworkUpdate>,
110 impl_writeable_tlv_based_enum_upgradable!(PathFailure,
112 (0, network_update, upgradable_option),
114 (2, InitialSend) => {
115 (0, err, upgradable_required),
119 #[derive(Clone, Debug, PartialEq, Eq)]
120 /// The reason the channel was closed. See individual variants more details.
121 pub enum ClosureReason {
122 /// Closure generated from receiving a peer error message.
124 /// Our counterparty may have broadcasted their latest commitment state, and we have
126 CounterpartyForceClosed {
127 /// The error which the peer sent us.
129 /// Be careful about printing the peer_msg, a well-crafted message could exploit
130 /// a security vulnerability in the terminal emulator or the logging subsystem.
131 /// To be safe, use `Display` on `UntrustedString`
133 /// [`UntrustedString`]: crate::util::string::UntrustedString
134 peer_msg: UntrustedString,
136 /// Closure generated from [`ChannelManager::force_close_channel`], called by the user.
138 /// [`ChannelManager::force_close_channel`]: crate::ln::channelmanager::ChannelManager::force_close_channel.
140 /// The channel was closed after negotiating a cooperative close and we've now broadcasted
141 /// the cooperative close transaction. Note the shutdown may have been initiated by us.
142 //TODO: split between CounterpartyInitiated/LocallyInitiated
144 /// A commitment transaction was confirmed on chain, closing the channel. Most likely this
145 /// commitment transaction came from our counterparty, but it may also have come from
146 /// a copy of our own `ChannelMonitor`.
147 CommitmentTxConfirmed,
148 /// The funding transaction failed to confirm in a timely manner on an inbound channel.
150 /// Closure generated from processing an event, likely a HTLC forward/relay/reception.
152 /// A developer-readable error message which we generated.
155 /// The peer disconnected prior to funding completing. In this case the spec mandates that we
156 /// forget the channel entirely - we can attempt again if the peer reconnects.
158 /// This includes cases where we restarted prior to funding completion, including prior to the
159 /// initial [`ChannelMonitor`] persistence completing.
161 /// In LDK versions prior to 0.0.107 this could also occur if we were unable to connect to the
162 /// peer because of mutual incompatibility between us and our channel counterparty.
164 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
166 /// Closure generated from `ChannelManager::read` if the [`ChannelMonitor`] is newer than
167 /// the [`ChannelManager`] deserialized.
169 /// [`ChannelMonitor`]: crate::chain::channelmonitor::ChannelMonitor
170 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
171 OutdatedChannelManager
174 impl core::fmt::Display for ClosureReason {
175 fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
176 f.write_str("Channel closed because ")?;
178 ClosureReason::CounterpartyForceClosed { peer_msg } => {
179 f.write_fmt(format_args!("counterparty force-closed with message: {}", peer_msg))
181 ClosureReason::HolderForceClosed => f.write_str("user manually force-closed the channel"),
182 ClosureReason::CooperativeClosure => f.write_str("the channel was cooperatively closed"),
183 ClosureReason::CommitmentTxConfirmed => f.write_str("commitment or closing transaction was confirmed on chain."),
184 ClosureReason::FundingTimedOut => write!(f, "funding transaction failed to confirm within {} blocks", FUNDING_CONF_DEADLINE_BLOCKS),
185 ClosureReason::ProcessingError { err } => {
186 f.write_str("of an exception: ")?;
189 ClosureReason::DisconnectedPeer => f.write_str("the peer disconnected prior to the channel being funded"),
190 ClosureReason::OutdatedChannelManager => f.write_str("the ChannelManager read from disk was stale compared to ChannelMonitor(s)"),
195 impl_writeable_tlv_based_enum_upgradable!(ClosureReason,
196 (0, CounterpartyForceClosed) => { (1, peer_msg, required) },
197 (1, FundingTimedOut) => {},
198 (2, HolderForceClosed) => {},
199 (6, CommitmentTxConfirmed) => {},
200 (4, CooperativeClosure) => {},
201 (8, ProcessingError) => { (1, err, required) },
202 (10, DisconnectedPeer) => {},
203 (12, OutdatedChannelManager) => {},
206 /// Intended destination of a failed HTLC as indicated in [`Event::HTLCHandlingFailed`].
207 #[derive(Clone, Debug, PartialEq, Eq)]
208 pub enum HTLCDestination {
209 /// We tried forwarding to a channel but failed to do so. An example of such an instance is when
210 /// there is insufficient capacity in our outbound channel.
212 /// The `node_id` of the next node. For backwards compatibility, this field is
213 /// marked as optional, versions prior to 0.0.110 may not always be able to provide
214 /// counterparty node information.
215 node_id: Option<PublicKey>,
216 /// The outgoing `channel_id` between us and the next node.
217 channel_id: [u8; 32],
219 /// Scenario where we are unsure of the next node to forward the HTLC to.
221 /// Short channel id we are requesting to forward an HTLC to.
222 requested_forward_scid: u64,
224 /// We couldn't forward to the outgoing scid. An example would be attempting to send a duplicate
227 /// Short channel id we are requesting to forward an HTLC to.
228 requested_forward_scid: u64
230 /// Failure scenario where an HTLC may have been forwarded to be intended for us,
231 /// but is invalid for some reason, so we reject it.
233 /// Some of the reasons may include:
235 /// * Expected MPP amount to claim does not equal HTLC total
236 /// * Claimable amount does not match expected amount
238 /// The payment hash of the payment we attempted to process.
239 payment_hash: PaymentHash
243 impl_writeable_tlv_based_enum_upgradable!(HTLCDestination,
244 (0, NextHopChannel) => {
245 (0, node_id, required),
246 (2, channel_id, required),
248 (1, InvalidForward) => {
249 (0, requested_forward_scid, required),
251 (2, UnknownNextHop) => {
252 (0, requested_forward_scid, required),
254 (4, FailedPayment) => {
255 (0, payment_hash, required),
260 /// A descriptor used to sign for a commitment transaction's anchor output.
261 #[derive(Clone, Debug, PartialEq, Eq)]
262 pub struct AnchorDescriptor {
263 /// A unique identifier used along with `channel_value_satoshis` to re-derive the
264 /// [`InMemorySigner`] required to sign `input`.
266 /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
267 pub channel_keys_id: [u8; 32],
268 /// The value in satoshis of the channel we're attempting to spend the anchor output of. This is
269 /// used along with `channel_keys_id` to re-derive the [`InMemorySigner`] required to sign
272 /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
273 pub channel_value_satoshis: u64,
274 /// The transaction input's outpoint corresponding to the commitment transaction's anchor
276 pub outpoint: OutPoint,
280 /// A descriptor used to sign for a commitment transaction's HTLC output.
281 #[derive(Clone, Debug, PartialEq, Eq)]
282 pub struct HTLCDescriptor {
283 /// A unique identifier used along with `channel_value_satoshis` to re-derive the
284 /// [`InMemorySigner`] required to sign `input`.
286 /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
287 pub channel_keys_id: [u8; 32],
288 /// The value in satoshis of the channel we're attempting to spend the anchor output of. This is
289 /// used along with `channel_keys_id` to re-derive the [`InMemorySigner`] required to sign
292 /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
293 pub channel_value_satoshis: u64,
294 /// The necessary channel parameters that need to be provided to the re-derived
295 /// [`InMemorySigner`] through [`ChannelSigner::provide_channel_parameters`].
297 /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
298 /// [`ChannelSigner::provide_channel_parameters`]: crate::chain::keysinterface::ChannelSigner::provide_channel_parameters
299 pub channel_parameters: ChannelTransactionParameters,
300 /// The txid of the commitment transaction in which the HTLC output lives.
301 pub commitment_txid: Txid,
302 /// The number of the commitment transaction in which the HTLC output lives.
303 pub per_commitment_number: u64,
304 /// The details of the HTLC as it appears in the commitment transaction.
305 pub htlc: HTLCOutputInCommitment,
306 /// The preimage, if `Some`, to claim the HTLC output with. If `None`, the timeout path must be
308 pub preimage: Option<PaymentPreimage>,
309 /// The counterparty's signature required to spend the HTLC output.
310 pub counterparty_sig: Signature
314 impl HTLCDescriptor {
315 /// Returns the unsigned transaction input spending the HTLC output in the commitment
317 pub fn unsigned_tx_input(&self) -> TxIn {
318 chan_utils::build_htlc_input(&self.commitment_txid, &self.htlc, true /* opt_anchors */)
321 /// Returns the delayed output created as a result of spending the HTLC output in the commitment
323 pub fn tx_output<C: secp256k1::Signing + secp256k1::Verification>(
324 &self, per_commitment_point: &PublicKey, secp: &Secp256k1<C>
326 let channel_params = self.channel_parameters.as_holder_broadcastable();
327 let broadcaster_keys = channel_params.broadcaster_pubkeys();
328 let counterparty_keys = channel_params.countersignatory_pubkeys();
329 let broadcaster_delayed_key = chan_utils::derive_public_key(
330 secp, per_commitment_point, &broadcaster_keys.delayed_payment_basepoint
332 let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
333 secp, per_commitment_point, &counterparty_keys.revocation_basepoint
335 chan_utils::build_htlc_output(
336 0 /* feerate_per_kw */, channel_params.contest_delay(), &self.htlc, true /* opt_anchors */,
337 false /* use_non_zero_fee_anchors */, &broadcaster_delayed_key, &counterparty_revocation_key
341 /// Returns the witness script of the HTLC output in the commitment transaction.
342 pub fn witness_script<C: secp256k1::Signing + secp256k1::Verification>(
343 &self, per_commitment_point: &PublicKey, secp: &Secp256k1<C>
345 let channel_params = self.channel_parameters.as_holder_broadcastable();
346 let broadcaster_keys = channel_params.broadcaster_pubkeys();
347 let counterparty_keys = channel_params.countersignatory_pubkeys();
348 let broadcaster_htlc_key = chan_utils::derive_public_key(
349 secp, per_commitment_point, &broadcaster_keys.htlc_basepoint
351 let counterparty_htlc_key = chan_utils::derive_public_key(
352 secp, per_commitment_point, &counterparty_keys.htlc_basepoint
354 let counterparty_revocation_key = chan_utils::derive_public_revocation_key(
355 secp, per_commitment_point, &counterparty_keys.revocation_basepoint
357 chan_utils::get_htlc_redeemscript_with_explicit_keys(
358 &self.htlc, true /* opt_anchors */, &broadcaster_htlc_key, &counterparty_htlc_key,
359 &counterparty_revocation_key,
363 /// Returns the fully signed witness required to spend the HTLC output in the commitment
365 pub fn tx_input_witness(&self, signature: &Signature, witness_script: &Script) -> Witness {
366 chan_utils::build_htlc_input_witness(
367 signature, &self.counterparty_sig, &self.preimage, witness_script, true /* opt_anchors */
373 /// Represents the different types of transactions, originating from LDK, to be bumped.
374 #[derive(Clone, Debug, PartialEq, Eq)]
375 pub enum BumpTransactionEvent {
376 /// Indicates that a channel featuring anchor outputs is to be closed by broadcasting the local
377 /// commitment transaction. Since commitment transactions have a static feerate pre-agreed upon,
378 /// they may need additional fees to be attached through a child transaction using the popular
379 /// [Child-Pays-For-Parent](https://bitcoinops.org/en/topics/cpfp) fee bumping technique. This
380 /// child transaction must include the anchor input described within `anchor_descriptor` along
381 /// with additional inputs to meet the target feerate. Failure to meet the target feerate
382 /// decreases the confirmation odds of the transaction package (which includes the commitment
383 /// and child anchor transactions), possibly resulting in a loss of funds. Once the transaction
384 /// is constructed, it must be fully signed for and broadcast by the consumer of the event
385 /// along with the `commitment_tx` enclosed. Note that the `commitment_tx` must always be
386 /// broadcast first, as the child anchor transaction depends on it.
388 /// The consumer should be able to sign for any of the additional inputs included within the
389 /// child anchor transaction. To sign its anchor input, an [`InMemorySigner`] should be
390 /// re-derived through [`KeysManager::derive_channel_keys`] with the help of
391 /// [`AnchorDescriptor::channel_keys_id`] and [`AnchorDescriptor::channel_value_satoshis`]. The
392 /// anchor input signature can be computed with [`EcdsaChannelSigner::sign_holder_anchor_input`],
393 /// which can then be provided to [`build_anchor_input_witness`] along with the `funding_pubkey`
394 /// to obtain the full witness required to spend.
396 /// It is possible to receive more than one instance of this event if a valid child anchor
397 /// transaction is never broadcast or is but not with a sufficient fee to be mined. Care should
398 /// be taken by the consumer of the event to ensure any future iterations of the child anchor
399 /// transaction adhere to the [Replace-By-Fee
400 /// rules](https://github.com/bitcoin/bitcoin/blob/master/doc/policy/mempool-replacements.md)
401 /// for fee bumps to be accepted into the mempool, and eventually the chain. As the frequency of
402 /// these events is not user-controlled, users may ignore/drop the event if they are no longer
403 /// able to commit external confirmed funds to the child anchor transaction.
405 /// The set of `pending_htlcs` on the commitment transaction to be broadcast can be inspected to
406 /// determine whether a significant portion of the channel's funds are allocated to HTLCs,
407 /// enabling users to make their own decisions regarding the importance of the commitment
408 /// transaction's confirmation. Note that this is not required, but simply exists as an option
409 /// for users to override LDK's behavior. On commitments with no HTLCs (indicated by those with
410 /// an empty `pending_htlcs`), confirmation of the commitment transaction can be considered to
413 /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
414 /// [`KeysManager::derive_channel_keys`]: crate::chain::keysinterface::KeysManager::derive_channel_keys
415 /// [`EcdsaChannelSigner::sign_holder_anchor_input`]: crate::chain::keysinterface::EcdsaChannelSigner::sign_holder_anchor_input
416 /// [`build_anchor_input_witness`]: crate::ln::chan_utils::build_anchor_input_witness
418 /// The target feerate that the transaction package, which consists of the commitment
419 /// transaction and the to-be-crafted child anchor transaction, must meet.
420 package_target_feerate_sat_per_1000_weight: u32,
421 /// The channel's commitment transaction to bump the fee of. This transaction should be
422 /// broadcast along with the anchor transaction constructed as a result of consuming this
424 commitment_tx: Transaction,
425 /// The absolute fee in satoshis of the commitment transaction. This can be used along the
426 /// with weight of the commitment transaction to determine its feerate.
427 commitment_tx_fee_satoshis: u64,
428 /// The descriptor to sign the anchor input of the anchor transaction constructed as a
429 /// result of consuming this event.
430 anchor_descriptor: AnchorDescriptor,
431 /// The set of pending HTLCs on the commitment transaction that need to be resolved once the
432 /// commitment transaction confirms.
433 pending_htlcs: Vec<HTLCOutputInCommitment>,
435 /// Indicates that a channel featuring anchor outputs has unilaterally closed on-chain by a
436 /// holder commitment transaction and its HTLC(s) need to be resolved on-chain. With the
437 /// zero-HTLC-transaction-fee variant of anchor outputs, the pre-signed HTLC
438 /// transactions have a zero fee, thus requiring additional inputs and/or outputs to be attached
439 /// for a timely confirmation within the chain. These additional inputs and/or outputs must be
440 /// appended to the resulting HTLC transaction to meet the target feerate. Failure to meet the
441 /// target feerate decreases the confirmation odds of the transaction, possibly resulting in a
442 /// loss of funds. Once the transaction meets the target feerate, it must be signed for and
443 /// broadcast by the consumer of the event.
445 /// The consumer should be able to sign for any of the non-HTLC inputs added to the resulting
446 /// HTLC transaction. To sign HTLC inputs, an [`InMemorySigner`] should be re-derived through
447 /// [`KeysManager::derive_channel_keys`] with the help of `channel_keys_id` and
448 /// `channel_value_satoshis`. Each HTLC input's signature can be computed with
449 /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`], which can then be provided to
450 /// [`HTLCDescriptor::tx_input_witness`] to obtain the fully signed witness required to spend.
452 /// It is possible to receive more than one instance of this event if a valid HTLC transaction
453 /// is never broadcast or is but not with a sufficient fee to be mined. Care should be taken by
454 /// the consumer of the event to ensure any future iterations of the HTLC transaction adhere to
455 /// the [Replace-By-Fee
456 /// rules](https://github.com/bitcoin/bitcoin/blob/master/doc/policy/mempool-replacements.md)
457 /// for fee bumps to be accepted into the mempool, and eventually the chain. As the frequency of
458 /// these events is not user-controlled, users may ignore/drop the event if either they are no
459 /// longer able to commit external confirmed funds to the HTLC transaction or the fee committed
460 /// to the HTLC transaction is greater in value than the HTLCs being claimed.
462 /// [`InMemorySigner`]: crate::chain::keysinterface::InMemorySigner
463 /// [`KeysManager::derive_channel_keys`]: crate::chain::keysinterface::KeysManager::derive_channel_keys
464 /// [`EcdsaChannelSigner::sign_holder_htlc_transaction`]: crate::chain::keysinterface::EcdsaChannelSigner::sign_holder_htlc_transaction
465 /// [`HTLCDescriptor::tx_input_witness`]: HTLCDescriptor::tx_input_witness
467 /// The target feerate that the resulting HTLC transaction must meet.
468 target_feerate_sat_per_1000_weight: u32,
469 /// The set of pending HTLCs on the confirmed commitment that need to be claimed, preferably
470 /// by the same transaction.
471 htlc_descriptors: Vec<HTLCDescriptor>,
475 /// Will be used in [`Event::HTLCIntercepted`] to identify the next hop in the HTLC's path.
476 /// Currently only used in serialization for the sake of maintaining compatibility. More variants
477 /// will be added for general-purpose HTLC forward intercepts as well as trampoline forward
478 /// intercepts in upcoming work.
479 enum InterceptNextHop {
481 requested_next_hop_scid: u64,
485 impl_writeable_tlv_based_enum!(InterceptNextHop,
487 (0, requested_next_hop_scid, required),
491 /// An Event which you should probably take some action in response to.
493 /// Note that while Writeable and Readable are implemented for Event, you probably shouldn't use
494 /// them directly as they don't round-trip exactly (for example FundingGenerationReady is never
495 /// written as it makes no sense to respond to it after reconnecting to peers).
496 #[derive(Clone, Debug, PartialEq, Eq)]
498 /// Used to indicate that the client should generate a funding transaction with the given
499 /// parameters and then call [`ChannelManager::funding_transaction_generated`].
500 /// Generated in [`ChannelManager`] message handling.
501 /// Note that *all inputs* in the funding transaction must spend SegWit outputs or your
502 /// counterparty can steal your funds!
504 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
505 /// [`ChannelManager::funding_transaction_generated`]: crate::ln::channelmanager::ChannelManager::funding_transaction_generated
506 FundingGenerationReady {
507 /// The random channel_id we picked which you'll need to pass into
508 /// [`ChannelManager::funding_transaction_generated`].
510 /// [`ChannelManager::funding_transaction_generated`]: crate::ln::channelmanager::ChannelManager::funding_transaction_generated
511 temporary_channel_id: [u8; 32],
512 /// The counterparty's node_id, which you'll need to pass back into
513 /// [`ChannelManager::funding_transaction_generated`].
515 /// [`ChannelManager::funding_transaction_generated`]: crate::ln::channelmanager::ChannelManager::funding_transaction_generated
516 counterparty_node_id: PublicKey,
517 /// The value, in satoshis, that the output should have.
518 channel_value_satoshis: u64,
519 /// The script which should be used in the transaction output.
520 output_script: Script,
521 /// The `user_channel_id` value passed in to [`ChannelManager::create_channel`], or a
522 /// random value for an inbound channel. This may be zero for objects serialized with LDK
523 /// versions prior to 0.0.113.
525 /// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
526 user_channel_id: u128,
528 /// Indicates that we've been offered a payment and it needs to be claimed via calling
529 /// [`ChannelManager::claim_funds`] with the preimage given in [`PaymentPurpose`].
531 /// Note that if the preimage is not known, you should call
532 /// [`ChannelManager::fail_htlc_backwards`] or [`ChannelManager::fail_htlc_backwards_with_reason`]
533 /// to free up resources for this HTLC and avoid network congestion.
534 /// If you fail to call either [`ChannelManager::claim_funds`], [`ChannelManager::fail_htlc_backwards`],
535 /// or [`ChannelManager::fail_htlc_backwards_with_reason`] within the HTLC's timeout, the HTLC will be
536 /// automatically failed.
539 /// LDK will not stop an inbound payment from being paid multiple times, so multiple
540 /// `PaymentClaimable` events may be generated for the same payment.
543 /// This event used to be called `PaymentReceived` in LDK versions 0.0.112 and earlier.
545 /// [`ChannelManager::claim_funds`]: crate::ln::channelmanager::ChannelManager::claim_funds
546 /// [`ChannelManager::fail_htlc_backwards`]: crate::ln::channelmanager::ChannelManager::fail_htlc_backwards
547 /// [`ChannelManager::fail_htlc_backwards_with_reason`]: crate::ln::channelmanager::ChannelManager::fail_htlc_backwards_with_reason
549 /// The node that will receive the payment after it has been claimed.
550 /// This is useful to identify payments received via [phantom nodes].
551 /// This field will always be filled in when the event was generated by LDK versions
552 /// 0.0.113 and above.
554 /// [phantom nodes]: crate::chain::keysinterface::PhantomKeysManager
555 receiver_node_id: Option<PublicKey>,
556 /// The hash for which the preimage should be handed to the ChannelManager. Note that LDK will
557 /// not stop you from registering duplicate payment hashes for inbound payments.
558 payment_hash: PaymentHash,
559 /// The value, in thousandths of a satoshi, that this payment is for.
561 /// Information for claiming this received payment, based on whether the purpose of the
562 /// payment is to pay an invoice or to send a spontaneous payment.
563 purpose: PaymentPurpose,
564 /// The `channel_id` indicating over which channel we received the payment.
565 via_channel_id: Option<[u8; 32]>,
566 /// The `user_channel_id` indicating over which channel we received the payment.
567 via_user_channel_id: Option<u128>,
569 /// Indicates a payment has been claimed and we've received money!
571 /// This most likely occurs when [`ChannelManager::claim_funds`] has been called in response
572 /// to an [`Event::PaymentClaimable`]. However, if we previously crashed during a
573 /// [`ChannelManager::claim_funds`] call you may see this event without a corresponding
574 /// [`Event::PaymentClaimable`] event.
577 /// LDK will not stop an inbound payment from being paid multiple times, so multiple
578 /// `PaymentClaimable` events may be generated for the same payment. If you then call
579 /// [`ChannelManager::claim_funds`] twice for the same [`Event::PaymentClaimable`] you may get
580 /// multiple `PaymentClaimed` events.
582 /// [`ChannelManager::claim_funds`]: crate::ln::channelmanager::ChannelManager::claim_funds
584 /// The node that received the payment.
585 /// This is useful to identify payments which were received via [phantom nodes].
586 /// This field will always be filled in when the event was generated by LDK versions
587 /// 0.0.113 and above.
589 /// [phantom nodes]: crate::chain::keysinterface::PhantomKeysManager
590 receiver_node_id: Option<PublicKey>,
591 /// The payment hash of the claimed payment. Note that LDK will not stop you from
592 /// registering duplicate payment hashes for inbound payments.
593 payment_hash: PaymentHash,
594 /// The value, in thousandths of a satoshi, that this payment is for.
596 /// The purpose of the claimed payment, i.e. whether the payment was for an invoice or a
597 /// spontaneous payment.
598 purpose: PaymentPurpose,
600 /// Indicates an outbound payment we made succeeded (i.e. it made it all the way to its target
601 /// and we got back the payment preimage for it).
603 /// Note for MPP payments: in rare cases, this event may be preceded by a `PaymentPathFailed`
604 /// event. In this situation, you SHOULD treat this payment as having succeeded.
606 /// The id returned by [`ChannelManager::send_payment`].
608 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
609 payment_id: Option<PaymentId>,
610 /// The preimage to the hash given to ChannelManager::send_payment.
611 /// Note that this serves as a payment receipt, if you wish to have such a thing, you must
612 /// store it somehow!
613 payment_preimage: PaymentPreimage,
614 /// The hash that was given to [`ChannelManager::send_payment`].
616 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
617 payment_hash: PaymentHash,
618 /// The total fee which was spent at intermediate hops in this payment, across all paths.
620 /// Note that, like [`Route::get_total_fees`] this does *not* include any potential
621 /// overpayment to the recipient node.
623 /// If the recipient or an intermediate node misbehaves and gives us free money, this may
624 /// overstate the amount paid, though this is unlikely.
626 /// [`Route::get_total_fees`]: crate::routing::router::Route::get_total_fees
627 fee_paid_msat: Option<u64>,
629 /// Indicates an outbound payment failed. Individual [`Event::PaymentPathFailed`] events
630 /// provide failure information for each path attempt in the payment, including retries.
632 /// This event is provided once there are no further pending HTLCs for the payment and the
633 /// payment is no longer retryable, due either to the [`Retry`] provided or
634 /// [`ChannelManager::abandon_payment`] having been called for the corresponding payment.
636 /// [`Retry`]: crate::ln::channelmanager::Retry
637 /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
639 /// The id returned by [`ChannelManager::send_payment`] and used with
640 /// [`ChannelManager::abandon_payment`].
642 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
643 /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
644 payment_id: PaymentId,
645 /// The hash that was given to [`ChannelManager::send_payment`].
647 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
648 payment_hash: PaymentHash,
650 /// Indicates that a path for an outbound payment was successful.
652 /// Always generated after [`Event::PaymentSent`] and thus useful for scoring channels. See
653 /// [`Event::PaymentSent`] for obtaining the payment preimage.
654 PaymentPathSuccessful {
655 /// The id returned by [`ChannelManager::send_payment`].
657 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
658 payment_id: PaymentId,
659 /// The hash that was given to [`ChannelManager::send_payment`].
661 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
662 payment_hash: Option<PaymentHash>,
663 /// The payment path that was successful.
665 /// May contain a closed channel if the HTLC sent along the path was fulfilled on chain.
668 /// Indicates an outbound HTLC we sent failed, likely due to an intermediary node being unable to
671 /// Note that this does *not* indicate that all paths for an MPP payment have failed, see
672 /// [`Event::PaymentFailed`].
674 /// See [`ChannelManager::abandon_payment`] for giving up on this payment before its retries have
677 /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
679 /// The id returned by [`ChannelManager::send_payment`] and used with
680 /// [`ChannelManager::abandon_payment`].
682 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
683 /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
684 payment_id: Option<PaymentId>,
685 /// The hash that was given to [`ChannelManager::send_payment`].
687 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
688 payment_hash: PaymentHash,
689 /// Indicates the payment was rejected for some reason by the recipient. This implies that
690 /// the payment has failed, not just the route in question. If this is not set, the payment may
691 /// be retried via a different route.
692 payment_failed_permanently: bool,
693 /// Extra error details based on the failure type. May contain an update that needs to be
694 /// applied to the [`NetworkGraph`].
696 /// [`NetworkGraph`]: crate::routing::gossip::NetworkGraph
697 failure: PathFailure,
698 /// The payment path that failed.
700 /// The channel responsible for the failed payment path.
702 /// Note that for route hints or for the first hop in a path this may be an SCID alias and
703 /// may not refer to a channel in the public network graph. These aliases may also collide
704 /// with channels in the public network graph.
706 /// If this is `Some`, then the corresponding channel should be avoided when the payment is
707 /// retried. May be `None` for older [`Event`] serializations.
708 short_channel_id: Option<u64>,
710 error_code: Option<u16>,
712 error_data: Option<Vec<u8>>,
714 /// Indicates that a probe payment we sent returned successful, i.e., only failed at the destination.
716 /// The id returned by [`ChannelManager::send_probe`].
718 /// [`ChannelManager::send_probe`]: crate::ln::channelmanager::ChannelManager::send_probe
719 payment_id: PaymentId,
720 /// The hash generated by [`ChannelManager::send_probe`].
722 /// [`ChannelManager::send_probe`]: crate::ln::channelmanager::ChannelManager::send_probe
723 payment_hash: PaymentHash,
724 /// The payment path that was successful.
727 /// Indicates that a probe payment we sent failed at an intermediary node on the path.
729 /// The id returned by [`ChannelManager::send_probe`].
731 /// [`ChannelManager::send_probe`]: crate::ln::channelmanager::ChannelManager::send_probe
732 payment_id: PaymentId,
733 /// The hash generated by [`ChannelManager::send_probe`].
735 /// [`ChannelManager::send_probe`]: crate::ln::channelmanager::ChannelManager::send_probe
736 payment_hash: PaymentHash,
737 /// The payment path that failed.
739 /// The channel responsible for the failed probe.
741 /// Note that for route hints or for the first hop in a path this may be an SCID alias and
742 /// may not refer to a channel in the public network graph. These aliases may also collide
743 /// with channels in the public network graph.
744 short_channel_id: Option<u64>,
746 /// Used to indicate that [`ChannelManager::process_pending_htlc_forwards`] should be called at
747 /// a time in the future.
749 /// [`ChannelManager::process_pending_htlc_forwards`]: crate::ln::channelmanager::ChannelManager::process_pending_htlc_forwards
750 PendingHTLCsForwardable {
751 /// The minimum amount of time that should be waited prior to calling
752 /// process_pending_htlc_forwards. To increase the effort required to correlate payments,
753 /// you should wait a random amount of time in roughly the range (now + time_forwardable,
754 /// now + 5*time_forwardable).
755 time_forwardable: Duration,
757 /// Used to indicate that we've intercepted an HTLC forward. This event will only be generated if
758 /// you've encoded an intercept scid in the receiver's invoice route hints using
759 /// [`ChannelManager::get_intercept_scid`] and have set [`UserConfig::accept_intercept_htlcs`].
761 /// [`ChannelManager::forward_intercepted_htlc`] or
762 /// [`ChannelManager::fail_intercepted_htlc`] MUST be called in response to this event. See
763 /// their docs for more information.
765 /// [`ChannelManager::get_intercept_scid`]: crate::ln::channelmanager::ChannelManager::get_intercept_scid
766 /// [`UserConfig::accept_intercept_htlcs`]: crate::util::config::UserConfig::accept_intercept_htlcs
767 /// [`ChannelManager::forward_intercepted_htlc`]: crate::ln::channelmanager::ChannelManager::forward_intercepted_htlc
768 /// [`ChannelManager::fail_intercepted_htlc`]: crate::ln::channelmanager::ChannelManager::fail_intercepted_htlc
770 /// An id to help LDK identify which HTLC is being forwarded or failed.
771 intercept_id: InterceptId,
772 /// The fake scid that was programmed as the next hop's scid, generated using
773 /// [`ChannelManager::get_intercept_scid`].
775 /// [`ChannelManager::get_intercept_scid`]: crate::ln::channelmanager::ChannelManager::get_intercept_scid
776 requested_next_hop_scid: u64,
777 /// The payment hash used for this HTLC.
778 payment_hash: PaymentHash,
779 /// How many msats were received on the inbound edge of this HTLC.
780 inbound_amount_msat: u64,
781 /// How many msats the payer intended to route to the next node. Depending on the reason you are
782 /// intercepting this payment, you might take a fee by forwarding less than this amount.
784 /// Note that LDK will NOT check that expected fees were factored into this value. You MUST
785 /// check that whatever fee you want has been included here or subtract it as required. Further,
786 /// LDK will not stop you from forwarding more than you received.
787 expected_outbound_amount_msat: u64,
789 /// Used to indicate that an output which you should know how to spend was confirmed on chain
790 /// and is now spendable.
791 /// Such an output will *not* ever be spent by rust-lightning, and are not at risk of your
792 /// counterparty spending them due to some kind of timeout. Thus, you need to store them
793 /// somewhere and spend them when you create on-chain transactions.
795 /// The outputs which you should store as spendable by you.
796 outputs: Vec<SpendableOutputDescriptor>,
798 /// This event is generated when a payment has been successfully forwarded through us and a
799 /// forwarding fee earned.
801 /// The incoming channel between the previous node and us. This is only `None` for events
802 /// generated or serialized by versions prior to 0.0.107.
803 prev_channel_id: Option<[u8; 32]>,
804 /// The outgoing channel between the next node and us. This is only `None` for events
805 /// generated or serialized by versions prior to 0.0.107.
806 next_channel_id: Option<[u8; 32]>,
807 /// The fee, in milli-satoshis, which was earned as a result of the payment.
809 /// Note that if we force-closed the channel over which we forwarded an HTLC while the HTLC
810 /// was pending, the amount the next hop claimed will have been rounded down to the nearest
811 /// whole satoshi. Thus, the fee calculated here may be higher than expected as we still
812 /// claimed the full value in millisatoshis from the source. In this case,
813 /// `claim_from_onchain_tx` will be set.
815 /// If the channel which sent us the payment has been force-closed, we will claim the funds
816 /// via an on-chain transaction. In that case we do not yet know the on-chain transaction
817 /// fees which we will spend and will instead set this to `None`. It is possible duplicate
818 /// `PaymentForwarded` events are generated for the same payment iff `fee_earned_msat` is
820 fee_earned_msat: Option<u64>,
821 /// If this is `true`, the forwarded HTLC was claimed by our counterparty via an on-chain
823 claim_from_onchain_tx: bool,
825 /// Used to indicate that a channel with the given `channel_id` is ready to
826 /// be used. This event is emitted either when the funding transaction has been confirmed
827 /// on-chain, or, in case of a 0conf channel, when both parties have confirmed the channel
830 /// The channel_id of the channel that is ready.
831 channel_id: [u8; 32],
832 /// The `user_channel_id` value passed in to [`ChannelManager::create_channel`] for outbound
833 /// channels, or to [`ChannelManager::accept_inbound_channel`] for inbound channels if
834 /// [`UserConfig::manually_accept_inbound_channels`] config flag is set to true. Otherwise
835 /// `user_channel_id` will be randomized for an inbound channel.
837 /// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
838 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
839 /// [`UserConfig::manually_accept_inbound_channels`]: crate::util::config::UserConfig::manually_accept_inbound_channels
840 user_channel_id: u128,
841 /// The node_id of the channel counterparty.
842 counterparty_node_id: PublicKey,
843 /// The features that this channel will operate with.
844 channel_type: ChannelTypeFeatures,
846 /// Used to indicate that a previously opened channel with the given `channel_id` is in the
847 /// process of closure.
849 /// The channel_id of the channel which has been closed. Note that on-chain transactions
850 /// resolving the channel are likely still awaiting confirmation.
851 channel_id: [u8; 32],
852 /// The `user_channel_id` value passed in to [`ChannelManager::create_channel`] for outbound
853 /// channels, or to [`ChannelManager::accept_inbound_channel`] for inbound channels if
854 /// [`UserConfig::manually_accept_inbound_channels`] config flag is set to true. Otherwise
855 /// `user_channel_id` will be randomized for inbound channels.
856 /// This may be zero for inbound channels serialized prior to 0.0.113 and will always be
857 /// zero for objects serialized with LDK versions prior to 0.0.102.
859 /// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
860 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
861 /// [`UserConfig::manually_accept_inbound_channels`]: crate::util::config::UserConfig::manually_accept_inbound_channels
862 user_channel_id: u128,
863 /// The reason the channel was closed.
864 reason: ClosureReason
866 /// Used to indicate to the user that they can abandon the funding transaction and recycle the
867 /// inputs for another purpose.
869 /// The channel_id of the channel which has been closed.
870 channel_id: [u8; 32],
871 /// The full transaction received from the user
872 transaction: Transaction
874 /// Indicates a request to open a new channel by a peer.
876 /// To accept the request, call [`ChannelManager::accept_inbound_channel`]. To reject the
877 /// request, call [`ChannelManager::force_close_without_broadcasting_txn`].
879 /// The event is only triggered when a new open channel request is received and the
880 /// [`UserConfig::manually_accept_inbound_channels`] config flag is set to true.
882 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
883 /// [`ChannelManager::force_close_without_broadcasting_txn`]: crate::ln::channelmanager::ChannelManager::force_close_without_broadcasting_txn
884 /// [`UserConfig::manually_accept_inbound_channels`]: crate::util::config::UserConfig::manually_accept_inbound_channels
886 /// The temporary channel ID of the channel requested to be opened.
888 /// When responding to the request, the `temporary_channel_id` should be passed
889 /// back to the ChannelManager through [`ChannelManager::accept_inbound_channel`] to accept,
890 /// or through [`ChannelManager::force_close_without_broadcasting_txn`] to reject.
892 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
893 /// [`ChannelManager::force_close_without_broadcasting_txn`]: crate::ln::channelmanager::ChannelManager::force_close_without_broadcasting_txn
894 temporary_channel_id: [u8; 32],
895 /// The node_id of the counterparty requesting to open the channel.
897 /// When responding to the request, the `counterparty_node_id` should be passed
898 /// back to the `ChannelManager` through [`ChannelManager::accept_inbound_channel`] to
899 /// accept the request, or through [`ChannelManager::force_close_without_broadcasting_txn`] to reject the
902 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
903 /// [`ChannelManager::force_close_without_broadcasting_txn`]: crate::ln::channelmanager::ChannelManager::force_close_without_broadcasting_txn
904 counterparty_node_id: PublicKey,
905 /// The channel value of the requested channel.
906 funding_satoshis: u64,
907 /// Our starting balance in the channel if the request is accepted, in milli-satoshi.
909 /// The features that this channel will operate with. If you reject the channel, a
910 /// well-behaved counterparty may automatically re-attempt the channel with a new set of
913 /// Note that if [`ChannelTypeFeatures::supports_scid_privacy`] returns true on this type,
914 /// the resulting [`ChannelManager`] will not be readable by versions of LDK prior to
917 /// Furthermore, note that if [`ChannelTypeFeatures::supports_zero_conf`] returns true on this type,
918 /// the resulting [`ChannelManager`] will not be readable by versions of LDK prior to
919 /// 0.0.107. Channels setting this type also need to get manually accepted via
920 /// [`crate::ln::channelmanager::ChannelManager::accept_inbound_channel_from_trusted_peer_0conf`],
921 /// or will be rejected otherwise.
923 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
924 channel_type: ChannelTypeFeatures,
926 /// Indicates that the HTLC was accepted, but could not be processed when or after attempting to
929 /// Some scenarios where this event may be sent include:
930 /// * Insufficient capacity in the outbound channel
931 /// * While waiting to forward the HTLC, the channel it is meant to be forwarded through closes
932 /// * When an unknown SCID is requested for forwarding a payment.
933 /// * Claiming an amount for an MPP payment that exceeds the HTLC total
934 /// * The HTLC has timed out
936 /// This event, however, does not get generated if an HTLC fails to meet the forwarding
937 /// requirements (i.e. insufficient fees paid, or a CLTV that is too soon).
939 /// The channel over which the HTLC was received.
940 prev_channel_id: [u8; 32],
941 /// Destination of the HTLC that failed to be processed.
942 failed_next_destination: HTLCDestination,
945 /// Indicates that a transaction originating from LDK needs to have its fee bumped. This event
946 /// requires confirmed external funds to be readily available to spend.
948 /// LDK does not currently generate this event. It is limited to the scope of channels with
949 /// anchor outputs, which will be introduced in a future release.
950 BumpTransaction(BumpTransactionEvent),
953 impl Writeable for Event {
954 fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
956 &Event::FundingGenerationReady { .. } => {
958 // We never write out FundingGenerationReady events as, upon disconnection, peers
959 // drop any channels which have not yet exchanged funding_signed.
961 &Event::PaymentClaimable { ref payment_hash, ref amount_msat, ref purpose, ref receiver_node_id, ref via_channel_id, ref via_user_channel_id } => {
963 let mut payment_secret = None;
964 let payment_preimage;
966 PaymentPurpose::InvoicePayment { payment_preimage: preimage, payment_secret: secret } => {
967 payment_secret = Some(secret);
968 payment_preimage = *preimage;
970 PaymentPurpose::SpontaneousPayment(preimage) => {
971 payment_preimage = Some(*preimage);
974 write_tlv_fields!(writer, {
975 (0, payment_hash, required),
976 (1, receiver_node_id, option),
977 (2, payment_secret, option),
978 (3, via_channel_id, option),
979 (4, amount_msat, required),
980 (5, via_user_channel_id, option),
981 (6, 0u64, required), // user_payment_id required for compatibility with 0.0.103 and earlier
982 (8, payment_preimage, option),
985 &Event::PaymentSent { ref payment_id, ref payment_preimage, ref payment_hash, ref fee_paid_msat } => {
987 write_tlv_fields!(writer, {
988 (0, payment_preimage, required),
989 (1, payment_hash, required),
990 (3, payment_id, option),
991 (5, fee_paid_msat, option),
994 &Event::PaymentPathFailed {
995 ref payment_id, ref payment_hash, ref payment_failed_permanently, ref failure,
996 ref path, ref short_channel_id,
1004 error_code.write(writer)?;
1006 error_data.write(writer)?;
1007 write_tlv_fields!(writer, {
1008 (0, payment_hash, required),
1009 (1, None::<NetworkUpdate>, option), // network_update in LDK versions prior to 0.0.114
1010 (2, payment_failed_permanently, required),
1011 (3, false, required), // all_paths_failed in LDK versions prior to 0.0.114
1012 (5, *path, vec_type),
1013 (7, short_channel_id, option),
1014 (9, None::<RouteParameters>, option), // retry in LDK versions prior to 0.0.115
1015 (11, payment_id, option),
1016 (13, failure, required),
1019 &Event::PendingHTLCsForwardable { time_forwardable: _ } => {
1021 // Note that we now ignore these on the read end as we'll re-generate them in
1022 // ChannelManager, we write them here only for backwards compatibility.
1024 &Event::SpendableOutputs { ref outputs } => {
1026 write_tlv_fields!(writer, {
1027 (0, WithoutLength(outputs), required),
1030 &Event::HTLCIntercepted { requested_next_hop_scid, payment_hash, inbound_amount_msat, expected_outbound_amount_msat, intercept_id } => {
1032 let intercept_scid = InterceptNextHop::FakeScid { requested_next_hop_scid };
1033 write_tlv_fields!(writer, {
1034 (0, intercept_id, required),
1035 (2, intercept_scid, required),
1036 (4, payment_hash, required),
1037 (6, inbound_amount_msat, required),
1038 (8, expected_outbound_amount_msat, required),
1041 &Event::PaymentForwarded { fee_earned_msat, prev_channel_id, claim_from_onchain_tx, next_channel_id } => {
1043 write_tlv_fields!(writer, {
1044 (0, fee_earned_msat, option),
1045 (1, prev_channel_id, option),
1046 (2, claim_from_onchain_tx, required),
1047 (3, next_channel_id, option),
1050 &Event::ChannelClosed { ref channel_id, ref user_channel_id, ref reason } => {
1052 // `user_channel_id` used to be a single u64 value. In order to remain backwards
1053 // compatible with versions prior to 0.0.113, the u128 is serialized as two
1054 // separate u64 values.
1055 let user_channel_id_low = *user_channel_id as u64;
1056 let user_channel_id_high = (*user_channel_id >> 64) as u64;
1057 write_tlv_fields!(writer, {
1058 (0, channel_id, required),
1059 (1, user_channel_id_low, required),
1060 (2, reason, required),
1061 (3, user_channel_id_high, required),
1064 &Event::DiscardFunding { ref channel_id, ref transaction } => {
1065 11u8.write(writer)?;
1066 write_tlv_fields!(writer, {
1067 (0, channel_id, required),
1068 (2, transaction, required)
1071 &Event::PaymentPathSuccessful { ref payment_id, ref payment_hash, ref path } => {
1072 13u8.write(writer)?;
1073 write_tlv_fields!(writer, {
1074 (0, payment_id, required),
1075 (2, payment_hash, option),
1076 (4, *path, vec_type)
1079 &Event::PaymentFailed { ref payment_id, ref payment_hash } => {
1080 15u8.write(writer)?;
1081 write_tlv_fields!(writer, {
1082 (0, payment_id, required),
1083 (2, payment_hash, required),
1086 &Event::OpenChannelRequest { .. } => {
1087 17u8.write(writer)?;
1088 // We never write the OpenChannelRequest events as, upon disconnection, peers
1089 // drop any channels which have not yet exchanged funding_signed.
1091 &Event::PaymentClaimed { ref payment_hash, ref amount_msat, ref purpose, ref receiver_node_id } => {
1092 19u8.write(writer)?;
1093 write_tlv_fields!(writer, {
1094 (0, payment_hash, required),
1095 (1, receiver_node_id, option),
1096 (2, purpose, required),
1097 (4, amount_msat, required),
1100 &Event::ProbeSuccessful { ref payment_id, ref payment_hash, ref path } => {
1101 21u8.write(writer)?;
1102 write_tlv_fields!(writer, {
1103 (0, payment_id, required),
1104 (2, payment_hash, required),
1105 (4, *path, vec_type)
1108 &Event::ProbeFailed { ref payment_id, ref payment_hash, ref path, ref short_channel_id } => {
1109 23u8.write(writer)?;
1110 write_tlv_fields!(writer, {
1111 (0, payment_id, required),
1112 (2, payment_hash, required),
1113 (4, *path, vec_type),
1114 (6, short_channel_id, option),
1117 &Event::HTLCHandlingFailed { ref prev_channel_id, ref failed_next_destination } => {
1118 25u8.write(writer)?;
1119 write_tlv_fields!(writer, {
1120 (0, prev_channel_id, required),
1121 (2, failed_next_destination, required),
1125 &Event::BumpTransaction(ref event)=> {
1126 27u8.write(writer)?;
1128 // We never write the ChannelClose|HTLCResolution events as they'll be replayed
1129 // upon restarting anyway if they remain unresolved.
1130 BumpTransactionEvent::ChannelClose { .. } => {}
1131 BumpTransactionEvent::HTLCResolution { .. } => {}
1133 write_tlv_fields!(writer, {}); // Write a length field for forwards compat
1135 &Event::ChannelReady { ref channel_id, ref user_channel_id, ref counterparty_node_id, ref channel_type } => {
1136 29u8.write(writer)?;
1137 write_tlv_fields!(writer, {
1138 (0, channel_id, required),
1139 (2, user_channel_id, required),
1140 (4, counterparty_node_id, required),
1141 (6, channel_type, required),
1144 // Note that, going forward, all new events must only write data inside of
1145 // `write_tlv_fields`. Versions 0.0.101+ will ignore odd-numbered events that write
1146 // data via `write_tlv_fields`.
1151 impl MaybeReadable for Event {
1152 fn read<R: io::Read>(reader: &mut R) -> Result<Option<Self>, msgs::DecodeError> {
1153 match Readable::read(reader)? {
1154 // Note that we do not write a length-prefixed TLV for FundingGenerationReady events,
1155 // unlike all other events, thus we return immediately here.
1159 let mut payment_hash = PaymentHash([0; 32]);
1160 let mut payment_preimage = None;
1161 let mut payment_secret = None;
1162 let mut amount_msat = 0;
1163 let mut receiver_node_id = None;
1164 let mut _user_payment_id = None::<u64>; // For compatibility with 0.0.103 and earlier
1165 let mut via_channel_id = None;
1166 let mut via_user_channel_id = None;
1167 read_tlv_fields!(reader, {
1168 (0, payment_hash, required),
1169 (1, receiver_node_id, option),
1170 (2, payment_secret, option),
1171 (3, via_channel_id, option),
1172 (4, amount_msat, required),
1173 (5, via_user_channel_id, option),
1174 (6, _user_payment_id, option),
1175 (8, payment_preimage, option),
1177 let purpose = match payment_secret {
1178 Some(secret) => PaymentPurpose::InvoicePayment {
1180 payment_secret: secret
1182 None if payment_preimage.is_some() => PaymentPurpose::SpontaneousPayment(payment_preimage.unwrap()),
1183 None => return Err(msgs::DecodeError::InvalidValue),
1185 Ok(Some(Event::PaymentClaimable {
1191 via_user_channel_id,
1198 let mut payment_preimage = PaymentPreimage([0; 32]);
1199 let mut payment_hash = None;
1200 let mut payment_id = None;
1201 let mut fee_paid_msat = None;
1202 read_tlv_fields!(reader, {
1203 (0, payment_preimage, required),
1204 (1, payment_hash, option),
1205 (3, payment_id, option),
1206 (5, fee_paid_msat, option),
1208 if payment_hash.is_none() {
1209 payment_hash = Some(PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()));
1211 Ok(Some(Event::PaymentSent {
1214 payment_hash: payment_hash.unwrap(),
1223 let error_code = Readable::read(reader)?;
1225 let error_data = Readable::read(reader)?;
1226 let mut payment_hash = PaymentHash([0; 32]);
1227 let mut payment_failed_permanently = false;
1228 let mut network_update = None;
1229 let mut path: Option<Vec<RouteHop>> = Some(vec![]);
1230 let mut short_channel_id = None;
1231 let mut payment_id = None;
1232 let mut failure_opt = None;
1233 read_tlv_fields!(reader, {
1234 (0, payment_hash, required),
1235 (1, network_update, upgradable_option),
1236 (2, payment_failed_permanently, required),
1237 (5, path, vec_type),
1238 (7, short_channel_id, option),
1239 (11, payment_id, option),
1240 (13, failure_opt, upgradable_option),
1242 let failure = failure_opt.unwrap_or_else(|| PathFailure::OnPath { network_update });
1243 Ok(Some(Event::PaymentPathFailed {
1246 payment_failed_permanently,
1248 path: path.unwrap(),
1261 let mut outputs = WithoutLength(Vec::new());
1262 read_tlv_fields!(reader, {
1263 (0, outputs, required),
1265 Ok(Some(Event::SpendableOutputs { outputs: outputs.0 }))
1270 let mut payment_hash = PaymentHash([0; 32]);
1271 let mut intercept_id = InterceptId([0; 32]);
1272 let mut requested_next_hop_scid = InterceptNextHop::FakeScid { requested_next_hop_scid: 0 };
1273 let mut inbound_amount_msat = 0;
1274 let mut expected_outbound_amount_msat = 0;
1275 read_tlv_fields!(reader, {
1276 (0, intercept_id, required),
1277 (2, requested_next_hop_scid, required),
1278 (4, payment_hash, required),
1279 (6, inbound_amount_msat, required),
1280 (8, expected_outbound_amount_msat, required),
1282 let next_scid = match requested_next_hop_scid {
1283 InterceptNextHop::FakeScid { requested_next_hop_scid: scid } => scid
1285 Ok(Some(Event::HTLCIntercepted {
1287 requested_next_hop_scid: next_scid,
1288 inbound_amount_msat,
1289 expected_outbound_amount_msat,
1295 let mut fee_earned_msat = None;
1296 let mut prev_channel_id = None;
1297 let mut claim_from_onchain_tx = false;
1298 let mut next_channel_id = None;
1299 read_tlv_fields!(reader, {
1300 (0, fee_earned_msat, option),
1301 (1, prev_channel_id, option),
1302 (2, claim_from_onchain_tx, required),
1303 (3, next_channel_id, option),
1305 Ok(Some(Event::PaymentForwarded { fee_earned_msat, prev_channel_id, claim_from_onchain_tx, next_channel_id }))
1311 let mut channel_id = [0; 32];
1312 let mut reason = UpgradableRequired(None);
1313 let mut user_channel_id_low_opt: Option<u64> = None;
1314 let mut user_channel_id_high_opt: Option<u64> = None;
1315 read_tlv_fields!(reader, {
1316 (0, channel_id, required),
1317 (1, user_channel_id_low_opt, option),
1318 (2, reason, upgradable_required),
1319 (3, user_channel_id_high_opt, option),
1322 // `user_channel_id` used to be a single u64 value. In order to remain
1323 // backwards compatible with versions prior to 0.0.113, the u128 is serialized
1324 // as two separate u64 values.
1325 let user_channel_id = (user_channel_id_low_opt.unwrap_or(0) as u128) +
1326 ((user_channel_id_high_opt.unwrap_or(0) as u128) << 64);
1328 Ok(Some(Event::ChannelClosed { channel_id, user_channel_id, reason: _init_tlv_based_struct_field!(reason, upgradable_required) }))
1334 let mut channel_id = [0; 32];
1335 let mut transaction = Transaction{ version: 2, lock_time: PackedLockTime::ZERO, input: Vec::new(), output: Vec::new() };
1336 read_tlv_fields!(reader, {
1337 (0, channel_id, required),
1338 (2, transaction, required),
1340 Ok(Some(Event::DiscardFunding { channel_id, transaction } ))
1346 let mut payment_id = PaymentId([0; 32]);
1347 let mut payment_hash = None;
1348 let mut path: Option<Vec<RouteHop>> = Some(vec![]);
1349 read_tlv_fields!(reader, {
1350 (0, payment_id, required),
1351 (2, payment_hash, option),
1352 (4, path, vec_type),
1354 Ok(Some(Event::PaymentPathSuccessful {
1357 path: path.unwrap(),
1364 let mut payment_hash = PaymentHash([0; 32]);
1365 let mut payment_id = PaymentId([0; 32]);
1366 read_tlv_fields!(reader, {
1367 (0, payment_id, required),
1368 (2, payment_hash, required),
1370 Ok(Some(Event::PaymentFailed {
1378 // Value 17 is used for `Event::OpenChannelRequest`.
1383 let mut payment_hash = PaymentHash([0; 32]);
1384 let mut purpose = UpgradableRequired(None);
1385 let mut amount_msat = 0;
1386 let mut receiver_node_id = None;
1387 read_tlv_fields!(reader, {
1388 (0, payment_hash, required),
1389 (1, receiver_node_id, option),
1390 (2, purpose, upgradable_required),
1391 (4, amount_msat, required),
1393 Ok(Some(Event::PaymentClaimed {
1396 purpose: _init_tlv_based_struct_field!(purpose, upgradable_required),
1404 let mut payment_id = PaymentId([0; 32]);
1405 let mut payment_hash = PaymentHash([0; 32]);
1406 let mut path: Option<Vec<RouteHop>> = Some(vec![]);
1407 read_tlv_fields!(reader, {
1408 (0, payment_id, required),
1409 (2, payment_hash, required),
1410 (4, path, vec_type),
1412 Ok(Some(Event::ProbeSuccessful {
1415 path: path.unwrap(),
1422 let mut payment_id = PaymentId([0; 32]);
1423 let mut payment_hash = PaymentHash([0; 32]);
1424 let mut path: Option<Vec<RouteHop>> = Some(vec![]);
1425 let mut short_channel_id = None;
1426 read_tlv_fields!(reader, {
1427 (0, payment_id, required),
1428 (2, payment_hash, required),
1429 (4, path, vec_type),
1430 (6, short_channel_id, option),
1432 Ok(Some(Event::ProbeFailed {
1435 path: path.unwrap(),
1443 let mut prev_channel_id = [0; 32];
1444 let mut failed_next_destination_opt = UpgradableRequired(None);
1445 read_tlv_fields!(reader, {
1446 (0, prev_channel_id, required),
1447 (2, failed_next_destination_opt, upgradable_required),
1449 Ok(Some(Event::HTLCHandlingFailed {
1451 failed_next_destination: _init_tlv_based_struct_field!(failed_next_destination_opt, upgradable_required),
1459 let mut channel_id = [0; 32];
1460 let mut user_channel_id: u128 = 0;
1461 let mut counterparty_node_id = RequiredWrapper(None);
1462 let mut channel_type = RequiredWrapper(None);
1463 read_tlv_fields!(reader, {
1464 (0, channel_id, required),
1465 (2, user_channel_id, required),
1466 (4, counterparty_node_id, required),
1467 (6, channel_type, required),
1470 Ok(Some(Event::ChannelReady {
1473 counterparty_node_id: counterparty_node_id.0.unwrap(),
1474 channel_type: channel_type.0.unwrap()
1479 // Versions prior to 0.0.100 did not ignore odd types, instead returning InvalidValue.
1480 // Version 0.0.100 failed to properly ignore odd types, possibly resulting in corrupt
1482 x if x % 2 == 1 => {
1483 // If the event is of unknown type, assume it was written with `write_tlv_fields`,
1484 // which prefixes the whole thing with a length BigSize. Because the event is
1485 // odd-type unknown, we should treat it as `Ok(None)` even if it has some TLV
1486 // fields that are even. Thus, we avoid using `read_tlv_fields` and simply read
1487 // exactly the number of bytes specified, ignoring them entirely.
1488 let tlv_len: BigSize = Readable::read(reader)?;
1489 FixedLengthReader::new(reader, tlv_len.0)
1490 .eat_remaining().map_err(|_| msgs::DecodeError::ShortRead)?;
1493 _ => Err(msgs::DecodeError::InvalidValue)
1498 /// An event generated by ChannelManager which indicates a message should be sent to a peer (or
1499 /// broadcast to most peers).
1500 /// These events are handled by PeerManager::process_events if you are using a PeerManager.
1501 #[derive(Clone, Debug)]
1502 pub enum MessageSendEvent {
1503 /// Used to indicate that we've accepted a channel open and should send the accept_channel
1504 /// message provided to the given peer.
1506 /// The node_id of the node which should receive this message
1508 /// The message which should be sent.
1509 msg: msgs::AcceptChannel,
1511 /// Used to indicate that we've initiated a channel open and should send the open_channel
1512 /// message provided to the given peer.
1514 /// The node_id of the node which should receive this message
1516 /// The message which should be sent.
1517 msg: msgs::OpenChannel,
1519 /// Used to indicate that a funding_created message should be sent to the peer with the given node_id.
1520 SendFundingCreated {
1521 /// The node_id of the node which should receive this message
1523 /// The message which should be sent.
1524 msg: msgs::FundingCreated,
1526 /// Used to indicate that a funding_signed message should be sent to the peer with the given node_id.
1528 /// The node_id of the node which should receive this message
1530 /// The message which should be sent.
1531 msg: msgs::FundingSigned,
1533 /// Used to indicate that a channel_ready message should be sent to the peer with the given node_id.
1535 /// The node_id of the node which should receive these message(s)
1537 /// The channel_ready message which should be sent.
1538 msg: msgs::ChannelReady,
1540 /// Used to indicate that an announcement_signatures message should be sent to the peer with the given node_id.
1541 SendAnnouncementSignatures {
1542 /// The node_id of the node which should receive these message(s)
1544 /// The announcement_signatures message which should be sent.
1545 msg: msgs::AnnouncementSignatures,
1547 /// Used to indicate that a series of HTLC update messages, as well as a commitment_signed
1548 /// message should be sent to the peer with the given node_id.
1550 /// The node_id of the node which should receive these message(s)
1552 /// The update messages which should be sent. ALL messages in the struct should be sent!
1553 updates: msgs::CommitmentUpdate,
1555 /// Used to indicate that a revoke_and_ack message should be sent to the peer with the given node_id.
1557 /// The node_id of the node which should receive this message
1559 /// The message which should be sent.
1560 msg: msgs::RevokeAndACK,
1562 /// Used to indicate that a closing_signed message should be sent to the peer with the given node_id.
1564 /// The node_id of the node which should receive this message
1566 /// The message which should be sent.
1567 msg: msgs::ClosingSigned,
1569 /// Used to indicate that a shutdown message should be sent to the peer with the given node_id.
1571 /// The node_id of the node which should receive this message
1573 /// The message which should be sent.
1574 msg: msgs::Shutdown,
1576 /// Used to indicate that a channel_reestablish message should be sent to the peer with the given node_id.
1577 SendChannelReestablish {
1578 /// The node_id of the node which should receive this message
1580 /// The message which should be sent.
1581 msg: msgs::ChannelReestablish,
1583 /// Used to send a channel_announcement and channel_update to a specific peer, likely on
1584 /// initial connection to ensure our peers know about our channels.
1585 SendChannelAnnouncement {
1586 /// The node_id of the node which should receive this message
1588 /// The channel_announcement which should be sent.
1589 msg: msgs::ChannelAnnouncement,
1590 /// The followup channel_update which should be sent.
1591 update_msg: msgs::ChannelUpdate,
1593 /// Used to indicate that a channel_announcement and channel_update should be broadcast to all
1594 /// peers (except the peer with node_id either msg.contents.node_id_1 or msg.contents.node_id_2).
1596 /// Note that after doing so, you very likely (unless you did so very recently) want to
1597 /// broadcast a node_announcement (e.g. via [`PeerManager::broadcast_node_announcement`]). This
1598 /// ensures that any nodes which see our channel_announcement also have a relevant
1599 /// node_announcement, including relevant feature flags which may be important for routing
1600 /// through or to us.
1602 /// [`PeerManager::broadcast_node_announcement`]: crate::ln::peer_handler::PeerManager::broadcast_node_announcement
1603 BroadcastChannelAnnouncement {
1604 /// The channel_announcement which should be sent.
1605 msg: msgs::ChannelAnnouncement,
1606 /// The followup channel_update which should be sent.
1607 update_msg: Option<msgs::ChannelUpdate>,
1609 /// Used to indicate that a channel_update should be broadcast to all peers.
1610 BroadcastChannelUpdate {
1611 /// The channel_update which should be sent.
1612 msg: msgs::ChannelUpdate,
1614 /// Used to indicate that a node_announcement should be broadcast to all peers.
1615 BroadcastNodeAnnouncement {
1616 /// The node_announcement which should be sent.
1617 msg: msgs::NodeAnnouncement,
1619 /// Used to indicate that a channel_update should be sent to a single peer.
1620 /// In contrast to [`Self::BroadcastChannelUpdate`], this is used when the channel is a
1621 /// private channel and we shouldn't be informing all of our peers of channel parameters.
1623 /// The node_id of the node which should receive this message
1625 /// The channel_update which should be sent.
1626 msg: msgs::ChannelUpdate,
1628 /// Broadcast an error downstream to be handled
1630 /// The node_id of the node which should receive this message
1632 /// The action which should be taken.
1633 action: msgs::ErrorAction
1635 /// Query a peer for channels with funding transaction UTXOs in a block range.
1636 SendChannelRangeQuery {
1637 /// The node_id of this message recipient
1639 /// The query_channel_range which should be sent.
1640 msg: msgs::QueryChannelRange,
1642 /// Request routing gossip messages from a peer for a list of channels identified by
1643 /// their short_channel_ids.
1645 /// The node_id of this message recipient
1647 /// The query_short_channel_ids which should be sent.
1648 msg: msgs::QueryShortChannelIds,
1650 /// Sends a reply to a channel range query. This may be one of several SendReplyChannelRange events
1651 /// emitted during processing of the query.
1652 SendReplyChannelRange {
1653 /// The node_id of this message recipient
1655 /// The reply_channel_range which should be sent.
1656 msg: msgs::ReplyChannelRange,
1658 /// Sends a timestamp filter for inbound gossip. This should be sent on each new connection to
1659 /// enable receiving gossip messages from the peer.
1660 SendGossipTimestampFilter {
1661 /// The node_id of this message recipient
1663 /// The gossip_timestamp_filter which should be sent.
1664 msg: msgs::GossipTimestampFilter,
1668 /// A trait indicating an object may generate message send events
1669 pub trait MessageSendEventsProvider {
1670 /// Gets the list of pending events which were generated by previous actions, clearing the list
1672 fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent>;
1675 /// A trait indicating an object may generate onion messages to send
1676 pub trait OnionMessageProvider {
1677 /// Gets the next pending onion message for the peer with the given node id.
1678 fn next_onion_message_for_peer(&self, peer_node_id: PublicKey) -> Option<msgs::OnionMessage>;
1681 /// A trait indicating an object may generate events.
1683 /// Events are processed by passing an [`EventHandler`] to [`process_pending_events`].
1685 /// Implementations of this trait may also feature an async version of event handling, as shown with
1686 /// [`ChannelManager::process_pending_events_async`] and
1687 /// [`ChainMonitor::process_pending_events_async`].
1691 /// When using this trait, [`process_pending_events`] will call [`handle_event`] for each pending
1692 /// event since the last invocation.
1694 /// In order to ensure no [`Event`]s are lost, implementors of this trait will persist [`Event`]s
1695 /// and replay any unhandled events on startup. An [`Event`] is considered handled when
1696 /// [`process_pending_events`] returns, thus handlers MUST fully handle [`Event`]s and persist any
1697 /// relevant changes to disk *before* returning.
1699 /// Further, because an application may crash between an [`Event`] being handled and the
1700 /// implementor of this trait being re-serialized, [`Event`] handling must be idempotent - in
1701 /// effect, [`Event`]s may be replayed.
1703 /// Note, handlers may call back into the provider and thus deadlocking must be avoided. Be sure to
1704 /// consult the provider's documentation on the implication of processing events and how a handler
1705 /// may safely use the provider (e.g., see [`ChannelManager::process_pending_events`] and
1706 /// [`ChainMonitor::process_pending_events`]).
1708 /// (C-not implementable) As there is likely no reason for a user to implement this trait on their
1711 /// [`process_pending_events`]: Self::process_pending_events
1712 /// [`handle_event`]: EventHandler::handle_event
1713 /// [`ChannelManager::process_pending_events`]: crate::ln::channelmanager::ChannelManager#method.process_pending_events
1714 /// [`ChainMonitor::process_pending_events`]: crate::chain::chainmonitor::ChainMonitor#method.process_pending_events
1715 /// [`ChannelManager::process_pending_events_async`]: crate::ln::channelmanager::ChannelManager::process_pending_events_async
1716 /// [`ChainMonitor::process_pending_events_async`]: crate::chain::chainmonitor::ChainMonitor::process_pending_events_async
1717 pub trait EventsProvider {
1718 /// Processes any events generated since the last call using the given event handler.
1720 /// See the trait-level documentation for requirements.
1721 fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler;
1724 /// A trait implemented for objects handling events from [`EventsProvider`].
1726 /// An async variation also exists for implementations of [`EventsProvider`] that support async
1727 /// event handling. The async event handler should satisfy the generic bounds: `F:
1728 /// core::future::Future, H: Fn(Event) -> F`.
1729 pub trait EventHandler {
1730 /// Handles the given [`Event`].
1732 /// See [`EventsProvider`] for details that must be considered when implementing this method.
1733 fn handle_event(&self, event: Event);
1736 impl<F> EventHandler for F where F: Fn(Event) {
1737 fn handle_event(&self, event: Event) {
1742 impl<T: EventHandler> EventHandler for Arc<T> {
1743 fn handle_event(&self, event: Event) {
1744 self.deref().handle_event(event)