]> git.bitcoin.ninja Git - rust-lightning/blob - lightning/src/util/events.rs
Rename `FundingLocked` to `ChannelReady`.
[rust-lightning] / lightning / src / util / events.rs
1 // This file is Copyright its original authors, visible in version control
2 // history.
3 //
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
8 // licenses.
9
10 //! Events are returned from various bits in the library which indicate some action must be taken
11 //! by the client.
12 //!
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
15 //! few other things.
16
17 use chain::keysinterface::SpendableOutputDescriptor;
18 use ln::channelmanager::PaymentId;
19 use ln::channel::FUNDING_CONF_DEADLINE_BLOCKS;
20 use ln::features::ChannelTypeFeatures;
21 use ln::msgs;
22 use ln::msgs::DecodeError;
23 use ln::{PaymentPreimage, PaymentHash, PaymentSecret};
24 use routing::network_graph::NetworkUpdate;
25 use util::ser::{BigSize, FixedLengthReader, Writeable, Writer, MaybeReadable, Readable, VecReadWrapper, VecWriteWrapper};
26 use routing::router::{RouteHop, RouteParameters};
27
28 use bitcoin::Transaction;
29 use bitcoin::blockdata::script::Script;
30 use bitcoin::hashes::Hash;
31 use bitcoin::hashes::sha256::Hash as Sha256;
32 use bitcoin::secp256k1::PublicKey;
33 use io;
34 use prelude::*;
35 use core::time::Duration;
36 use core::ops::Deref;
37 use sync::Arc;
38
39 /// Some information provided on receipt of payment depends on whether the payment received is a
40 /// spontaneous payment or a "conventional" lightning payment that's paying an invoice.
41 #[derive(Clone, Debug)]
42 pub enum PaymentPurpose {
43         /// Information for receiving a payment that we generated an invoice for.
44         InvoicePayment {
45                 /// The preimage to the payment_hash, if the payment hash (and secret) were fetched via
46                 /// [`ChannelManager::create_inbound_payment`]. If provided, this can be handed directly to
47                 /// [`ChannelManager::claim_funds`].
48                 ///
49                 /// [`ChannelManager::create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment
50                 /// [`ChannelManager::claim_funds`]: crate::ln::channelmanager::ChannelManager::claim_funds
51                 payment_preimage: Option<PaymentPreimage>,
52                 /// The "payment secret". This authenticates the sender to the recipient, preventing a
53                 /// number of deanonymization attacks during the routing process.
54                 /// It is provided here for your reference, however its accuracy is enforced directly by
55                 /// [`ChannelManager`] using the values you previously provided to
56                 /// [`ChannelManager::create_inbound_payment`] or
57                 /// [`ChannelManager::create_inbound_payment_for_hash`].
58                 ///
59                 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
60                 /// [`ChannelManager::create_inbound_payment`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment
61                 /// [`ChannelManager::create_inbound_payment_for_hash`]: crate::ln::channelmanager::ChannelManager::create_inbound_payment_for_hash
62                 payment_secret: PaymentSecret,
63         },
64         /// Because this is a spontaneous payment, the payer generated their own preimage rather than us
65         /// (the payee) providing a preimage.
66         SpontaneousPayment(PaymentPreimage),
67 }
68
69 impl_writeable_tlv_based_enum!(PaymentPurpose,
70         (0, InvoicePayment) => {
71                 (0, payment_preimage, option),
72                 (2, payment_secret, required),
73         };
74         (2, SpontaneousPayment)
75 );
76
77 #[derive(Clone, Debug, PartialEq)]
78 /// The reason the channel was closed. See individual variants more details.
79 pub enum ClosureReason {
80         /// Closure generated from receiving a peer error message.
81         ///
82         /// Our counterparty may have broadcasted their latest commitment state, and we have
83         /// as well.
84         CounterpartyForceClosed {
85                 /// The error which the peer sent us.
86                 ///
87                 /// The string should be sanitized before it is used (e.g emitted to logs
88                 /// or printed to stdout). Otherwise, a well crafted error message may exploit
89                 /// a security vulnerability in the terminal emulator or the logging subsystem.
90                 peer_msg: String,
91         },
92         /// Closure generated from [`ChannelManager::force_close_channel`], called by the user.
93         ///
94         /// [`ChannelManager::force_close_channel`]: crate::ln::channelmanager::ChannelManager::force_close_channel.
95         HolderForceClosed,
96         /// The channel was closed after negotiating a cooperative close and we've now broadcasted
97         /// the cooperative close transaction. Note the shutdown may have been initiated by us.
98         //TODO: split between CounterpartyInitiated/LocallyInitiated
99         CooperativeClosure,
100         /// A commitment transaction was confirmed on chain, closing the channel. Most likely this
101         /// commitment transaction came from our counterparty, but it may also have come from
102         /// a copy of our own `ChannelMonitor`.
103         CommitmentTxConfirmed,
104         /// The funding transaction failed to confirm in a timely manner on an inbound channel.
105         FundingTimedOut,
106         /// Closure generated from processing an event, likely a HTLC forward/relay/reception.
107         ProcessingError {
108                 /// A developer-readable error message which we generated.
109                 err: String,
110         },
111         /// The peer disconnected prior to funding completing. In this case the spec mandates that we
112         /// forget the channel entirely - we can attempt again if the peer reconnects.
113         ///
114         /// In LDK versions prior to 0.0.107 this could also occur if we were unable to connect to the
115         /// peer because of mutual incompatibility between us and our channel counterparty.
116         DisconnectedPeer,
117         /// Closure generated from `ChannelManager::read` if the ChannelMonitor is newer than
118         /// the ChannelManager deserialized.
119         OutdatedChannelManager
120 }
121
122 impl core::fmt::Display for ClosureReason {
123         fn fmt(&self, f: &mut core::fmt::Formatter) -> Result<(), core::fmt::Error> {
124                 f.write_str("Channel closed because ")?;
125                 match self {
126                         ClosureReason::CounterpartyForceClosed { peer_msg } => {
127                                 f.write_str("counterparty force-closed with message ")?;
128                                 f.write_str(&peer_msg)
129                         },
130                         ClosureReason::HolderForceClosed => f.write_str("user manually force-closed the channel"),
131                         ClosureReason::CooperativeClosure => f.write_str("the channel was cooperatively closed"),
132                         ClosureReason::CommitmentTxConfirmed => f.write_str("commitment or closing transaction was confirmed on chain."),
133                         ClosureReason::FundingTimedOut => write!(f, "funding transaction failed to confirm within {} blocks", FUNDING_CONF_DEADLINE_BLOCKS),
134                         ClosureReason::ProcessingError { err } => {
135                                 f.write_str("of an exception: ")?;
136                                 f.write_str(&err)
137                         },
138                         ClosureReason::DisconnectedPeer => f.write_str("the peer disconnected prior to the channel being funded"),
139                         ClosureReason::OutdatedChannelManager => f.write_str("the ChannelManager read from disk was stale compared to ChannelMonitor(s)"),
140                 }
141         }
142 }
143
144 impl_writeable_tlv_based_enum_upgradable!(ClosureReason,
145         (0, CounterpartyForceClosed) => { (1, peer_msg, required) },
146         (1, FundingTimedOut) => {},
147         (2, HolderForceClosed) => {},
148         (6, CommitmentTxConfirmed) => {},
149         (4, CooperativeClosure) => {},
150         (8, ProcessingError) => { (1, err, required) },
151         (10, DisconnectedPeer) => {},
152         (12, OutdatedChannelManager) => {},
153 );
154
155 /// An Event which you should probably take some action in response to.
156 ///
157 /// Note that while Writeable and Readable are implemented for Event, you probably shouldn't use
158 /// them directly as they don't round-trip exactly (for example FundingGenerationReady is never
159 /// written as it makes no sense to respond to it after reconnecting to peers).
160 #[derive(Clone, Debug)]
161 pub enum Event {
162         /// Used to indicate that the client should generate a funding transaction with the given
163         /// parameters and then call [`ChannelManager::funding_transaction_generated`].
164         /// Generated in [`ChannelManager`] message handling.
165         /// Note that *all inputs* in the funding transaction must spend SegWit outputs or your
166         /// counterparty can steal your funds!
167         ///
168         /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
169         /// [`ChannelManager::funding_transaction_generated`]: crate::ln::channelmanager::ChannelManager::funding_transaction_generated
170         FundingGenerationReady {
171                 /// The random channel_id we picked which you'll need to pass into
172                 /// [`ChannelManager::funding_transaction_generated`].
173                 ///
174                 /// [`ChannelManager::funding_transaction_generated`]: crate::ln::channelmanager::ChannelManager::funding_transaction_generated
175                 temporary_channel_id: [u8; 32],
176                 /// The counterparty's node_id, which you'll need to pass back into
177                 /// [`ChannelManager::funding_transaction_generated`].
178                 ///
179                 /// [`ChannelManager::funding_transaction_generated`]: crate::ln::channelmanager::ChannelManager::funding_transaction_generated
180                 counterparty_node_id: PublicKey,
181                 /// The value, in satoshis, that the output should have.
182                 channel_value_satoshis: u64,
183                 /// The script which should be used in the transaction output.
184                 output_script: Script,
185                 /// The `user_channel_id` value passed in to [`ChannelManager::create_channel`], or 0 for
186                 /// an inbound channel.
187                 ///
188                 /// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
189                 user_channel_id: u64,
190         },
191         /// Indicates we've received (an offer of) money! Just gotta dig out that payment preimage and
192         /// feed it to [`ChannelManager::claim_funds`] to get it....
193         ///
194         /// Note that if the preimage is not known, you should call
195         /// [`ChannelManager::fail_htlc_backwards`] to free up resources for this HTLC and avoid
196         /// network congestion.
197         /// If you fail to call either [`ChannelManager::claim_funds`] or
198         /// [`ChannelManager::fail_htlc_backwards`] within the HTLC's timeout, the HTLC will be
199         /// automatically failed.
200         ///
201         /// # Note
202         /// LDK will not stop an inbound payment from being paid multiple times, so multiple
203         /// `PaymentReceived` events may be generated for the same payment.
204         ///
205         /// [`ChannelManager::claim_funds`]: crate::ln::channelmanager::ChannelManager::claim_funds
206         /// [`ChannelManager::fail_htlc_backwards`]: crate::ln::channelmanager::ChannelManager::fail_htlc_backwards
207         PaymentReceived {
208                 /// The hash for which the preimage should be handed to the ChannelManager. Note that LDK will
209                 /// not stop you from registering duplicate payment hashes for inbound payments.
210                 payment_hash: PaymentHash,
211                 /// The value, in thousandths of a satoshi, that this payment is for.
212                 amount_msat: u64,
213                 /// Information for claiming this received payment, based on whether the purpose of the
214                 /// payment is to pay an invoice or to send a spontaneous payment.
215                 purpose: PaymentPurpose,
216         },
217         /// Indicates a payment has been claimed and we've received money!
218         ///
219         /// This most likely occurs when [`ChannelManager::claim_funds`] has been called in response
220         /// to an [`Event::PaymentReceived`]. However, if we previously crashed during a
221         /// [`ChannelManager::claim_funds`] call you may see this event without a corresponding
222         /// [`Event::PaymentReceived`] event.
223         ///
224         /// # Note
225         /// LDK will not stop an inbound payment from being paid multiple times, so multiple
226         /// `PaymentReceived` events may be generated for the same payment. If you then call
227         /// [`ChannelManager::claim_funds`] twice for the same [`Event::PaymentReceived`] you may get
228         /// multiple `PaymentClaimed` events.
229         ///
230         /// [`ChannelManager::claim_funds`]: crate::ln::channelmanager::ChannelManager::claim_funds
231         PaymentClaimed {
232                 /// The payment hash of the claimed payment. Note that LDK will not stop you from
233                 /// registering duplicate payment hashes for inbound payments.
234                 payment_hash: PaymentHash,
235                 /// The value, in thousandths of a satoshi, that this payment is for.
236                 amount_msat: u64,
237                 /// The purpose of this claimed payment, i.e. whether the payment was for an invoice or a
238                 /// spontaneous payment.
239                 purpose: PaymentPurpose,
240         },
241         /// Indicates an outbound payment we made succeeded (i.e. it made it all the way to its target
242         /// and we got back the payment preimage for it).
243         ///
244         /// Note for MPP payments: in rare cases, this event may be preceded by a `PaymentPathFailed`
245         /// event. In this situation, you SHOULD treat this payment as having succeeded.
246         PaymentSent {
247                 /// The id returned by [`ChannelManager::send_payment`] and used with
248                 /// [`ChannelManager::retry_payment`].
249                 ///
250                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
251                 /// [`ChannelManager::retry_payment`]: crate::ln::channelmanager::ChannelManager::retry_payment
252                 payment_id: Option<PaymentId>,
253                 /// The preimage to the hash given to ChannelManager::send_payment.
254                 /// Note that this serves as a payment receipt, if you wish to have such a thing, you must
255                 /// store it somehow!
256                 payment_preimage: PaymentPreimage,
257                 /// The hash that was given to [`ChannelManager::send_payment`].
258                 ///
259                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
260                 payment_hash: PaymentHash,
261                 /// The total fee which was spent at intermediate hops in this payment, across all paths.
262                 ///
263                 /// Note that, like [`Route::get_total_fees`] this does *not* include any potential
264                 /// overpayment to the recipient node.
265                 ///
266                 /// If the recipient or an intermediate node misbehaves and gives us free money, this may
267                 /// overstate the amount paid, though this is unlikely.
268                 ///
269                 /// [`Route::get_total_fees`]: crate::routing::router::Route::get_total_fees
270                 fee_paid_msat: Option<u64>,
271         },
272         /// Indicates an outbound payment failed. Individual [`Event::PaymentPathFailed`] events
273         /// provide failure information for each MPP part in the payment.
274         ///
275         /// This event is provided once there are no further pending HTLCs for the payment and the
276         /// payment is no longer retryable, either due to a several-block timeout or because
277         /// [`ChannelManager::abandon_payment`] was previously called for the corresponding payment.
278         ///
279         /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
280         PaymentFailed {
281                 /// The id returned by [`ChannelManager::send_payment`] and used with
282                 /// [`ChannelManager::retry_payment`] and [`ChannelManager::abandon_payment`].
283                 ///
284                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
285                 /// [`ChannelManager::retry_payment`]: crate::ln::channelmanager::ChannelManager::retry_payment
286                 /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
287                 payment_id: PaymentId,
288                 /// The hash that was given to [`ChannelManager::send_payment`].
289                 ///
290                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
291                 payment_hash: PaymentHash,
292         },
293         /// Indicates that a path for an outbound payment was successful.
294         ///
295         /// Always generated after [`Event::PaymentSent`] and thus useful for scoring channels. See
296         /// [`Event::PaymentSent`] for obtaining the payment preimage.
297         PaymentPathSuccessful {
298                 /// The id returned by [`ChannelManager::send_payment`] and used with
299                 /// [`ChannelManager::retry_payment`].
300                 ///
301                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
302                 /// [`ChannelManager::retry_payment`]: crate::ln::channelmanager::ChannelManager::retry_payment
303                 payment_id: PaymentId,
304                 /// The hash that was given to [`ChannelManager::send_payment`].
305                 ///
306                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
307                 payment_hash: Option<PaymentHash>,
308                 /// The payment path that was successful.
309                 ///
310                 /// May contain a closed channel if the HTLC sent along the path was fulfilled on chain.
311                 path: Vec<RouteHop>,
312         },
313         /// Indicates an outbound HTLC we sent failed. Probably some intermediary node dropped
314         /// something. You may wish to retry with a different route.
315         ///
316         /// Note that this does *not* indicate that all paths for an MPP payment have failed, see
317         /// [`Event::PaymentFailed`] and [`all_paths_failed`].
318         ///
319         /// [`all_paths_failed`]: Self::PaymentPathFailed::all_paths_failed
320         PaymentPathFailed {
321                 /// The id returned by [`ChannelManager::send_payment`] and used with
322                 /// [`ChannelManager::retry_payment`] and [`ChannelManager::abandon_payment`].
323                 ///
324                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
325                 /// [`ChannelManager::retry_payment`]: crate::ln::channelmanager::ChannelManager::retry_payment
326                 /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
327                 payment_id: Option<PaymentId>,
328                 /// The hash that was given to [`ChannelManager::send_payment`].
329                 ///
330                 /// [`ChannelManager::send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
331                 payment_hash: PaymentHash,
332                 /// Indicates the payment was rejected for some reason by the recipient. This implies that
333                 /// the payment has failed, not just the route in question. If this is not set, you may
334                 /// retry the payment via a different route.
335                 rejected_by_dest: bool,
336                 /// Any failure information conveyed via the Onion return packet by a node along the failed
337                 /// payment route.
338                 ///
339                 /// Should be applied to the [`NetworkGraph`] so that routing decisions can take into
340                 /// account the update. [`NetGraphMsgHandler`] is capable of doing this.
341                 ///
342                 /// [`NetworkGraph`]: crate::routing::network_graph::NetworkGraph
343                 /// [`NetGraphMsgHandler`]: crate::routing::network_graph::NetGraphMsgHandler
344                 network_update: Option<NetworkUpdate>,
345                 /// For both single-path and multi-path payments, this is set if all paths of the payment have
346                 /// failed. This will be set to false if (1) this is an MPP payment and (2) other parts of the
347                 /// larger MPP payment were still in flight when this event was generated.
348                 ///
349                 /// Note that if you are retrying individual MPP parts, using this value to determine if a
350                 /// payment has fully failed is race-y. Because multiple failures can happen prior to events
351                 /// being processed, you may retry in response to a first failure, with a second failure
352                 /// (with `all_paths_failed` set) still pending. Then, when the second failure is processed
353                 /// you will see `all_paths_failed` set even though the retry of the first failure still
354                 /// has an associated in-flight HTLC. See (1) for an example of such a failure.
355                 ///
356                 /// If you wish to retry individual MPP parts and learn when a payment has failed, you must
357                 /// call [`ChannelManager::abandon_payment`] and wait for a [`Event::PaymentFailed`] event.
358                 ///
359                 /// (1) <https://github.com/lightningdevkit/rust-lightning/issues/1164>
360                 ///
361                 /// [`ChannelManager::abandon_payment`]: crate::ln::channelmanager::ChannelManager::abandon_payment
362                 all_paths_failed: bool,
363                 /// The payment path that failed.
364                 path: Vec<RouteHop>,
365                 /// The channel responsible for the failed payment path.
366                 ///
367                 /// Note that for route hints or for the first hop in a path this may be an SCID alias and
368                 /// may not refer to a channel in the public network graph. These aliases may also collide
369                 /// with channels in the public network graph.
370                 ///
371                 /// If this is `Some`, then the corresponding channel should be avoided when the payment is
372                 /// retried. May be `None` for older [`Event`] serializations.
373                 short_channel_id: Option<u64>,
374                 /// Parameters needed to compute a new [`Route`] when retrying the failed payment path.
375                 ///
376                 /// See [`find_route`] for details.
377                 ///
378                 /// [`Route`]: crate::routing::router::Route
379                 /// [`find_route`]: crate::routing::router::find_route
380                 retry: Option<RouteParameters>,
381 #[cfg(test)]
382                 error_code: Option<u16>,
383 #[cfg(test)]
384                 error_data: Option<Vec<u8>>,
385         },
386         /// Used to indicate that [`ChannelManager::process_pending_htlc_forwards`] should be called at
387         /// a time in the future.
388         ///
389         /// [`ChannelManager::process_pending_htlc_forwards`]: crate::ln::channelmanager::ChannelManager::process_pending_htlc_forwards
390         PendingHTLCsForwardable {
391                 /// The minimum amount of time that should be waited prior to calling
392                 /// process_pending_htlc_forwards. To increase the effort required to correlate payments,
393                 /// you should wait a random amount of time in roughly the range (now + time_forwardable,
394                 /// now + 5*time_forwardable).
395                 time_forwardable: Duration,
396         },
397         /// Used to indicate that an output which you should know how to spend was confirmed on chain
398         /// and is now spendable.
399         /// Such an output will *not* ever be spent by rust-lightning, and are not at risk of your
400         /// counterparty spending them due to some kind of timeout. Thus, you need to store them
401         /// somewhere and spend them when you create on-chain transactions.
402         SpendableOutputs {
403                 /// The outputs which you should store as spendable by you.
404                 outputs: Vec<SpendableOutputDescriptor>,
405         },
406         /// This event is generated when a payment has been successfully forwarded through us and a
407         /// forwarding fee earned.
408         PaymentForwarded {
409                 /// The incoming channel between the previous node and us. This is only `None` for events
410                 /// generated or serialized by versions prior to 0.0.107.
411                 prev_channel_id: Option<[u8; 32]>,
412                 /// The outgoing channel between the next node and us. This is only `None` for events
413                 /// generated or serialized by versions prior to 0.0.107.
414                 next_channel_id: Option<[u8; 32]>,
415                 /// The fee, in milli-satoshis, which was earned as a result of the payment.
416                 ///
417                 /// Note that if we force-closed the channel over which we forwarded an HTLC while the HTLC
418                 /// was pending, the amount the next hop claimed will have been rounded down to the nearest
419                 /// whole satoshi. Thus, the fee calculated here may be higher than expected as we still
420                 /// claimed the full value in millisatoshis from the source. In this case,
421                 /// `claim_from_onchain_tx` will be set.
422                 ///
423                 /// If the channel which sent us the payment has been force-closed, we will claim the funds
424                 /// via an on-chain transaction. In that case we do not yet know the on-chain transaction
425                 /// fees which we will spend and will instead set this to `None`. It is possible duplicate
426                 /// `PaymentForwarded` events are generated for the same payment iff `fee_earned_msat` is
427                 /// `None`.
428                 fee_earned_msat: Option<u64>,
429                 /// If this is `true`, the forwarded HTLC was claimed by our counterparty via an on-chain
430                 /// transaction.
431                 claim_from_onchain_tx: bool,
432         },
433         /// Used to indicate that a channel with the given `channel_id` is in the process of closure.
434         ChannelClosed  {
435                 /// The channel_id of the channel which has been closed. Note that on-chain transactions
436                 /// resolving the channel are likely still awaiting confirmation.
437                 channel_id: [u8; 32],
438                 /// The `user_channel_id` value passed in to [`ChannelManager::create_channel`] for outbound
439                 /// channels, or to [`ChannelManager::accept_inbound_channel`] for inbound channels if
440                 /// [`UserConfig::manually_accept_inbound_channels`] config flag is set to true. Otherwise
441                 /// `user_channel_id` will be 0 for an inbound channel.
442                 /// This will always be zero for objects serialized with LDK versions prior to 0.0.102.
443                 ///
444                 /// [`ChannelManager::create_channel`]: crate::ln::channelmanager::ChannelManager::create_channel
445                 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
446                 /// [`UserConfig::manually_accept_inbound_channels`]: crate::util::config::UserConfig::manually_accept_inbound_channels
447                 user_channel_id: u64,
448                 /// The reason the channel was closed.
449                 reason: ClosureReason
450         },
451         /// Used to indicate to the user that they can abandon the funding transaction and recycle the
452         /// inputs for another purpose.
453         DiscardFunding {
454                 /// The channel_id of the channel which has been closed.
455                 channel_id: [u8; 32],
456                 /// The full transaction received from the user
457                 transaction: Transaction
458         },
459         /// Indicates a request to open a new channel by a peer.
460         ///
461         /// To accept the request, call [`ChannelManager::accept_inbound_channel`]. To reject the
462         /// request, call [`ChannelManager::force_close_channel`].
463         ///
464         /// The event is only triggered when a new open channel request is received and the
465         /// [`UserConfig::manually_accept_inbound_channels`] config flag is set to true.
466         ///
467         /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
468         /// [`ChannelManager::force_close_channel`]: crate::ln::channelmanager::ChannelManager::force_close_channel
469         /// [`UserConfig::manually_accept_inbound_channels`]: crate::util::config::UserConfig::manually_accept_inbound_channels
470         OpenChannelRequest {
471                 /// The temporary channel ID of the channel requested to be opened.
472                 ///
473                 /// When responding to the request, the `temporary_channel_id` should be passed
474                 /// back to the ChannelManager through [`ChannelManager::accept_inbound_channel`] to accept,
475                 /// or through [`ChannelManager::force_close_channel`] to reject.
476                 ///
477                 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
478                 /// [`ChannelManager::force_close_channel`]: crate::ln::channelmanager::ChannelManager::force_close_channel
479                 temporary_channel_id: [u8; 32],
480                 /// The node_id of the counterparty requesting to open the channel.
481                 ///
482                 /// When responding to the request, the `counterparty_node_id` should be passed
483                 /// back to the `ChannelManager` through [`ChannelManager::accept_inbound_channel`] to
484                 /// accept the request, or through [`ChannelManager::force_close_channel`] to reject the
485                 /// request.
486                 ///
487                 /// [`ChannelManager::accept_inbound_channel`]: crate::ln::channelmanager::ChannelManager::accept_inbound_channel
488                 /// [`ChannelManager::force_close_channel`]: crate::ln::channelmanager::ChannelManager::force_close_channel
489                 counterparty_node_id: PublicKey,
490                 /// The channel value of the requested channel.
491                 funding_satoshis: u64,
492                 /// Our starting balance in the channel if the request is accepted, in milli-satoshi.
493                 push_msat: u64,
494                 /// The features that this channel will operate with. If you reject the channel, a
495                 /// well-behaved counterparty may automatically re-attempt the channel with a new set of
496                 /// feature flags.
497                 ///
498                 /// Note that if [`ChannelTypeFeatures::supports_scid_privacy`] returns true on this type,
499                 /// the resulting [`ChannelManager`] will not be readable by versions of LDK prior to
500                 /// 0.0.106.
501                 ///
502                 /// [`ChannelManager`]: crate::ln::channelmanager::ChannelManager
503                 channel_type: ChannelTypeFeatures,
504         },
505 }
506
507 impl Writeable for Event {
508         fn write<W: Writer>(&self, writer: &mut W) -> Result<(), io::Error> {
509                 match self {
510                         &Event::FundingGenerationReady { .. } => {
511                                 0u8.write(writer)?;
512                                 // We never write out FundingGenerationReady events as, upon disconnection, peers
513                                 // drop any channels which have not yet exchanged funding_signed.
514                         },
515                         &Event::PaymentReceived { ref payment_hash, ref amount_msat, ref purpose } => {
516                                 1u8.write(writer)?;
517                                 let mut payment_secret = None;
518                                 let payment_preimage;
519                                 match &purpose {
520                                         PaymentPurpose::InvoicePayment { payment_preimage: preimage, payment_secret: secret } => {
521                                                 payment_secret = Some(secret);
522                                                 payment_preimage = *preimage;
523                                         },
524                                         PaymentPurpose::SpontaneousPayment(preimage) => {
525                                                 payment_preimage = Some(*preimage);
526                                         }
527                                 }
528                                 write_tlv_fields!(writer, {
529                                         (0, payment_hash, required),
530                                         (2, payment_secret, option),
531                                         (4, amount_msat, required),
532                                         (6, 0u64, required), // user_payment_id required for compatibility with 0.0.103 and earlier
533                                         (8, payment_preimage, option),
534                                 });
535                         },
536                         &Event::PaymentSent { ref payment_id, ref payment_preimage, ref payment_hash, ref fee_paid_msat } => {
537                                 2u8.write(writer)?;
538                                 write_tlv_fields!(writer, {
539                                         (0, payment_preimage, required),
540                                         (1, payment_hash, required),
541                                         (3, payment_id, option),
542                                         (5, fee_paid_msat, option),
543                                 });
544                         },
545                         &Event::PaymentPathFailed {
546                                 ref payment_id, ref payment_hash, ref rejected_by_dest, ref network_update,
547                                 ref all_paths_failed, ref path, ref short_channel_id, ref retry,
548                                 #[cfg(test)]
549                                 ref error_code,
550                                 #[cfg(test)]
551                                 ref error_data,
552                         } => {
553                                 3u8.write(writer)?;
554                                 #[cfg(test)]
555                                 error_code.write(writer)?;
556                                 #[cfg(test)]
557                                 error_data.write(writer)?;
558                                 write_tlv_fields!(writer, {
559                                         (0, payment_hash, required),
560                                         (1, network_update, option),
561                                         (2, rejected_by_dest, required),
562                                         (3, all_paths_failed, required),
563                                         (5, path, vec_type),
564                                         (7, short_channel_id, option),
565                                         (9, retry, option),
566                                         (11, payment_id, option),
567                                 });
568                         },
569                         &Event::PendingHTLCsForwardable { time_forwardable: _ } => {
570                                 4u8.write(writer)?;
571                                 // Note that we now ignore these on the read end as we'll re-generate them in
572                                 // ChannelManager, we write them here only for backwards compatibility.
573                         },
574                         &Event::SpendableOutputs { ref outputs } => {
575                                 5u8.write(writer)?;
576                                 write_tlv_fields!(writer, {
577                                         (0, VecWriteWrapper(outputs), required),
578                                 });
579                         },
580                         &Event::PaymentForwarded { fee_earned_msat, prev_channel_id, claim_from_onchain_tx, next_channel_id } => {
581                                 7u8.write(writer)?;
582                                 write_tlv_fields!(writer, {
583                                         (0, fee_earned_msat, option),
584                                         (1, prev_channel_id, option),
585                                         (2, claim_from_onchain_tx, required),
586                                         (3, next_channel_id, option),
587                                 });
588                         },
589                         &Event::ChannelClosed { ref channel_id, ref user_channel_id, ref reason } => {
590                                 9u8.write(writer)?;
591                                 write_tlv_fields!(writer, {
592                                         (0, channel_id, required),
593                                         (1, user_channel_id, required),
594                                         (2, reason, required)
595                                 });
596                         },
597                         &Event::DiscardFunding { ref channel_id, ref transaction } => {
598                                 11u8.write(writer)?;
599                                 write_tlv_fields!(writer, {
600                                         (0, channel_id, required),
601                                         (2, transaction, required)
602                                 })
603                         },
604                         &Event::PaymentPathSuccessful { ref payment_id, ref payment_hash, ref path } => {
605                                 13u8.write(writer)?;
606                                 write_tlv_fields!(writer, {
607                                         (0, payment_id, required),
608                                         (2, payment_hash, option),
609                                         (4, path, vec_type)
610                                 })
611                         },
612                         &Event::PaymentFailed { ref payment_id, ref payment_hash } => {
613                                 15u8.write(writer)?;
614                                 write_tlv_fields!(writer, {
615                                         (0, payment_id, required),
616                                         (2, payment_hash, required),
617                                 })
618                         },
619                         &Event::OpenChannelRequest { .. } => {
620                                 17u8.write(writer)?;
621                                 // We never write the OpenChannelRequest events as, upon disconnection, peers
622                                 // drop any channels which have not yet exchanged funding_signed.
623                         },
624                         &Event::PaymentClaimed { ref payment_hash, ref amount_msat, ref purpose } => {
625                                 19u8.write(writer)?;
626                                 write_tlv_fields!(writer, {
627                                         (0, payment_hash, required),
628                                         (2, purpose, required),
629                                         (4, amount_msat, required),
630                                 });
631                         },
632                         // Note that, going forward, all new events must only write data inside of
633                         // `write_tlv_fields`. Versions 0.0.101+ will ignore odd-numbered events that write
634                         // data via `write_tlv_fields`.
635                 }
636                 Ok(())
637         }
638 }
639 impl MaybeReadable for Event {
640         fn read<R: io::Read>(reader: &mut R) -> Result<Option<Self>, msgs::DecodeError> {
641                 match Readable::read(reader)? {
642                         // Note that we do not write a length-prefixed TLV for FundingGenerationReady events,
643                         // unlike all other events, thus we return immediately here.
644                         0u8 => Ok(None),
645                         1u8 => {
646                                 let f = || {
647                                         let mut payment_hash = PaymentHash([0; 32]);
648                                         let mut payment_preimage = None;
649                                         let mut payment_secret = None;
650                                         let mut amount_msat = 0;
651                                         let mut _user_payment_id = None::<u64>; // For compatibility with 0.0.103 and earlier
652                                         read_tlv_fields!(reader, {
653                                                 (0, payment_hash, required),
654                                                 (2, payment_secret, option),
655                                                 (4, amount_msat, required),
656                                                 (6, _user_payment_id, option),
657                                                 (8, payment_preimage, option),
658                                         });
659                                         let purpose = match payment_secret {
660                                                 Some(secret) => PaymentPurpose::InvoicePayment {
661                                                         payment_preimage,
662                                                         payment_secret: secret
663                                                 },
664                                                 None if payment_preimage.is_some() => PaymentPurpose::SpontaneousPayment(payment_preimage.unwrap()),
665                                                 None => return Err(msgs::DecodeError::InvalidValue),
666                                         };
667                                         Ok(Some(Event::PaymentReceived {
668                                                 payment_hash,
669                                                 amount_msat,
670                                                 purpose,
671                                         }))
672                                 };
673                                 f()
674                         },
675                         2u8 => {
676                                 let f = || {
677                                         let mut payment_preimage = PaymentPreimage([0; 32]);
678                                         let mut payment_hash = None;
679                                         let mut payment_id = None;
680                                         let mut fee_paid_msat = None;
681                                         read_tlv_fields!(reader, {
682                                                 (0, payment_preimage, required),
683                                                 (1, payment_hash, option),
684                                                 (3, payment_id, option),
685                                                 (5, fee_paid_msat, option),
686                                         });
687                                         if payment_hash.is_none() {
688                                                 payment_hash = Some(PaymentHash(Sha256::hash(&payment_preimage.0[..]).into_inner()));
689                                         }
690                                         Ok(Some(Event::PaymentSent {
691                                                 payment_id,
692                                                 payment_preimage,
693                                                 payment_hash: payment_hash.unwrap(),
694                                                 fee_paid_msat,
695                                         }))
696                                 };
697                                 f()
698                         },
699                         3u8 => {
700                                 let f = || {
701                                         #[cfg(test)]
702                                         let error_code = Readable::read(reader)?;
703                                         #[cfg(test)]
704                                         let error_data = Readable::read(reader)?;
705                                         let mut payment_hash = PaymentHash([0; 32]);
706                                         let mut rejected_by_dest = false;
707                                         let mut network_update = None;
708                                         let mut all_paths_failed = Some(true);
709                                         let mut path: Option<Vec<RouteHop>> = Some(vec![]);
710                                         let mut short_channel_id = None;
711                                         let mut retry = None;
712                                         let mut payment_id = None;
713                                         read_tlv_fields!(reader, {
714                                                 (0, payment_hash, required),
715                                                 (1, network_update, ignorable),
716                                                 (2, rejected_by_dest, required),
717                                                 (3, all_paths_failed, option),
718                                                 (5, path, vec_type),
719                                                 (7, short_channel_id, option),
720                                                 (9, retry, option),
721                                                 (11, payment_id, option),
722                                         });
723                                         Ok(Some(Event::PaymentPathFailed {
724                                                 payment_id,
725                                                 payment_hash,
726                                                 rejected_by_dest,
727                                                 network_update,
728                                                 all_paths_failed: all_paths_failed.unwrap(),
729                                                 path: path.unwrap(),
730                                                 short_channel_id,
731                                                 retry,
732                                                 #[cfg(test)]
733                                                 error_code,
734                                                 #[cfg(test)]
735                                                 error_data,
736                                         }))
737                                 };
738                                 f()
739                         },
740                         4u8 => Ok(None),
741                         5u8 => {
742                                 let f = || {
743                                         let mut outputs = VecReadWrapper(Vec::new());
744                                         read_tlv_fields!(reader, {
745                                                 (0, outputs, required),
746                                         });
747                                         Ok(Some(Event::SpendableOutputs { outputs: outputs.0 }))
748                                 };
749                                 f()
750                         },
751                         7u8 => {
752                                 let f = || {
753                                         let mut fee_earned_msat = None;
754                                         let mut prev_channel_id = None;
755                                         let mut claim_from_onchain_tx = false;
756                                         let mut next_channel_id = None;
757                                         read_tlv_fields!(reader, {
758                                                 (0, fee_earned_msat, option),
759                                                 (1, prev_channel_id, option),
760                                                 (2, claim_from_onchain_tx, required),
761                                                 (3, next_channel_id, option),
762                                         });
763                                         Ok(Some(Event::PaymentForwarded { fee_earned_msat, prev_channel_id, claim_from_onchain_tx, next_channel_id }))
764                                 };
765                                 f()
766                         },
767                         9u8 => {
768                                 let f = || {
769                                         let mut channel_id = [0; 32];
770                                         let mut reason = None;
771                                         let mut user_channel_id_opt = None;
772                                         read_tlv_fields!(reader, {
773                                                 (0, channel_id, required),
774                                                 (1, user_channel_id_opt, option),
775                                                 (2, reason, ignorable),
776                                         });
777                                         if reason.is_none() { return Ok(None); }
778                                         let user_channel_id = if let Some(id) = user_channel_id_opt { id } else { 0 };
779                                         Ok(Some(Event::ChannelClosed { channel_id, user_channel_id, reason: reason.unwrap() }))
780                                 };
781                                 f()
782                         },
783                         11u8 => {
784                                 let f = || {
785                                         let mut channel_id = [0; 32];
786                                         let mut transaction = Transaction{ version: 2, lock_time: 0, input: Vec::new(), output: Vec::new() };
787                                         read_tlv_fields!(reader, {
788                                                 (0, channel_id, required),
789                                                 (2, transaction, required),
790                                         });
791                                         Ok(Some(Event::DiscardFunding { channel_id, transaction } ))
792                                 };
793                                 f()
794                         },
795                         13u8 => {
796                                 let f = || {
797                                         let mut payment_id = PaymentId([0; 32]);
798                                         let mut payment_hash = None;
799                                         let mut path: Option<Vec<RouteHop>> = Some(vec![]);
800                                         read_tlv_fields!(reader, {
801                                                 (0, payment_id, required),
802                                                 (2, payment_hash, option),
803                                                 (4, path, vec_type),
804                                         });
805                                         Ok(Some(Event::PaymentPathSuccessful {
806                                                 payment_id,
807                                                 payment_hash,
808                                                 path: path.unwrap(),
809                                         }))
810                                 };
811                                 f()
812                         },
813                         15u8 => {
814                                 let f = || {
815                                         let mut payment_hash = PaymentHash([0; 32]);
816                                         let mut payment_id = PaymentId([0; 32]);
817                                         read_tlv_fields!(reader, {
818                                                 (0, payment_id, required),
819                                                 (2, payment_hash, required),
820                                         });
821                                         Ok(Some(Event::PaymentFailed {
822                                                 payment_id,
823                                                 payment_hash,
824                                         }))
825                                 };
826                                 f()
827                         },
828                         17u8 => {
829                                 // Value 17 is used for `Event::OpenChannelRequest`.
830                                 Ok(None)
831                         },
832                         19u8 => {
833                                 let f = || {
834                                         let mut payment_hash = PaymentHash([0; 32]);
835                                         let mut purpose = None;
836                                         let mut amount_msat = 0;
837                                         read_tlv_fields!(reader, {
838                                                 (0, payment_hash, required),
839                                                 (2, purpose, ignorable),
840                                                 (4, amount_msat, required),
841                                         });
842                                         if purpose.is_none() { return Ok(None); }
843                                         Ok(Some(Event::PaymentClaimed {
844                                                 payment_hash,
845                                                 purpose: purpose.unwrap(),
846                                                 amount_msat,
847                                         }))
848                                 };
849                                 f()
850                         },
851                         // Versions prior to 0.0.100 did not ignore odd types, instead returning InvalidValue.
852                         // Version 0.0.100 failed to properly ignore odd types, possibly resulting in corrupt
853                         // reads.
854                         x if x % 2 == 1 => {
855                                 // If the event is of unknown type, assume it was written with `write_tlv_fields`,
856                                 // which prefixes the whole thing with a length BigSize. Because the event is
857                                 // odd-type unknown, we should treat it as `Ok(None)` even if it has some TLV
858                                 // fields that are even. Thus, we avoid using `read_tlv_fields` and simply read
859                                 // exactly the number of bytes specified, ignoring them entirely.
860                                 let tlv_len: BigSize = Readable::read(reader)?;
861                                 FixedLengthReader::new(reader, tlv_len.0)
862                                         .eat_remaining().map_err(|_| msgs::DecodeError::ShortRead)?;
863                                 Ok(None)
864                         },
865                         _ => Err(msgs::DecodeError::InvalidValue)
866                 }
867         }
868 }
869
870 /// An event generated by ChannelManager which indicates a message should be sent to a peer (or
871 /// broadcast to most peers).
872 /// These events are handled by PeerManager::process_events if you are using a PeerManager.
873 #[derive(Clone, Debug)]
874 pub enum MessageSendEvent {
875         /// Used to indicate that we've accepted a channel open and should send the accept_channel
876         /// message provided to the given peer.
877         SendAcceptChannel {
878                 /// The node_id of the node which should receive this message
879                 node_id: PublicKey,
880                 /// The message which should be sent.
881                 msg: msgs::AcceptChannel,
882         },
883         /// Used to indicate that we've initiated a channel open and should send the open_channel
884         /// message provided to the given peer.
885         SendOpenChannel {
886                 /// The node_id of the node which should receive this message
887                 node_id: PublicKey,
888                 /// The message which should be sent.
889                 msg: msgs::OpenChannel,
890         },
891         /// Used to indicate that a funding_created message should be sent to the peer with the given node_id.
892         SendFundingCreated {
893                 /// The node_id of the node which should receive this message
894                 node_id: PublicKey,
895                 /// The message which should be sent.
896                 msg: msgs::FundingCreated,
897         },
898         /// Used to indicate that a funding_signed message should be sent to the peer with the given node_id.
899         SendFundingSigned {
900                 /// The node_id of the node which should receive this message
901                 node_id: PublicKey,
902                 /// The message which should be sent.
903                 msg: msgs::FundingSigned,
904         },
905         /// Used to indicate that a channel_ready message should be sent to the peer with the given node_id.
906         SendChannelReady {
907                 /// The node_id of the node which should receive these message(s)
908                 node_id: PublicKey,
909                 /// The channel_ready message which should be sent.
910                 msg: msgs::ChannelReady,
911         },
912         /// Used to indicate that an announcement_signatures message should be sent to the peer with the given node_id.
913         SendAnnouncementSignatures {
914                 /// The node_id of the node which should receive these message(s)
915                 node_id: PublicKey,
916                 /// The announcement_signatures message which should be sent.
917                 msg: msgs::AnnouncementSignatures,
918         },
919         /// Used to indicate that a series of HTLC update messages, as well as a commitment_signed
920         /// message should be sent to the peer with the given node_id.
921         UpdateHTLCs {
922                 /// The node_id of the node which should receive these message(s)
923                 node_id: PublicKey,
924                 /// The update messages which should be sent. ALL messages in the struct should be sent!
925                 updates: msgs::CommitmentUpdate,
926         },
927         /// Used to indicate that a revoke_and_ack message should be sent to the peer with the given node_id.
928         SendRevokeAndACK {
929                 /// The node_id of the node which should receive this message
930                 node_id: PublicKey,
931                 /// The message which should be sent.
932                 msg: msgs::RevokeAndACK,
933         },
934         /// Used to indicate that a closing_signed message should be sent to the peer with the given node_id.
935         SendClosingSigned {
936                 /// The node_id of the node which should receive this message
937                 node_id: PublicKey,
938                 /// The message which should be sent.
939                 msg: msgs::ClosingSigned,
940         },
941         /// Used to indicate that a shutdown message should be sent to the peer with the given node_id.
942         SendShutdown {
943                 /// The node_id of the node which should receive this message
944                 node_id: PublicKey,
945                 /// The message which should be sent.
946                 msg: msgs::Shutdown,
947         },
948         /// Used to indicate that a channel_reestablish message should be sent to the peer with the given node_id.
949         SendChannelReestablish {
950                 /// The node_id of the node which should receive this message
951                 node_id: PublicKey,
952                 /// The message which should be sent.
953                 msg: msgs::ChannelReestablish,
954         },
955         /// Used to indicate that a channel_announcement and channel_update should be broadcast to all
956         /// peers (except the peer with node_id either msg.contents.node_id_1 or msg.contents.node_id_2).
957         ///
958         /// Note that after doing so, you very likely (unless you did so very recently) want to call
959         /// ChannelManager::broadcast_node_announcement to trigger a BroadcastNodeAnnouncement event.
960         /// This ensures that any nodes which see our channel_announcement also have a relevant
961         /// node_announcement, including relevant feature flags which may be important for routing
962         /// through or to us.
963         BroadcastChannelAnnouncement {
964                 /// The channel_announcement which should be sent.
965                 msg: msgs::ChannelAnnouncement,
966                 /// The followup channel_update which should be sent.
967                 update_msg: msgs::ChannelUpdate,
968         },
969         /// Used to indicate that a node_announcement should be broadcast to all peers.
970         BroadcastNodeAnnouncement {
971                 /// The node_announcement which should be sent.
972                 msg: msgs::NodeAnnouncement,
973         },
974         /// Used to indicate that a channel_update should be broadcast to all peers.
975         BroadcastChannelUpdate {
976                 /// The channel_update which should be sent.
977                 msg: msgs::ChannelUpdate,
978         },
979         /// Used to indicate that a channel_update should be sent to a single peer.
980         /// In contrast to [`Self::BroadcastChannelUpdate`], this is used when the channel is a
981         /// private channel and we shouldn't be informing all of our peers of channel parameters.
982         SendChannelUpdate {
983                 /// The node_id of the node which should receive this message
984                 node_id: PublicKey,
985                 /// The channel_update which should be sent.
986                 msg: msgs::ChannelUpdate,
987         },
988         /// Broadcast an error downstream to be handled
989         HandleError {
990                 /// The node_id of the node which should receive this message
991                 node_id: PublicKey,
992                 /// The action which should be taken.
993                 action: msgs::ErrorAction
994         },
995         /// Query a peer for channels with funding transaction UTXOs in a block range.
996         SendChannelRangeQuery {
997                 /// The node_id of this message recipient
998                 node_id: PublicKey,
999                 /// The query_channel_range which should be sent.
1000                 msg: msgs::QueryChannelRange,
1001         },
1002         /// Request routing gossip messages from a peer for a list of channels identified by
1003         /// their short_channel_ids.
1004         SendShortIdsQuery {
1005                 /// The node_id of this message recipient
1006                 node_id: PublicKey,
1007                 /// The query_short_channel_ids which should be sent.
1008                 msg: msgs::QueryShortChannelIds,
1009         },
1010         /// Sends a reply to a channel range query. This may be one of several SendReplyChannelRange events
1011         /// emitted during processing of the query.
1012         SendReplyChannelRange {
1013                 /// The node_id of this message recipient
1014                 node_id: PublicKey,
1015                 /// The reply_channel_range which should be sent.
1016                 msg: msgs::ReplyChannelRange,
1017         },
1018         /// Sends a timestamp filter for inbound gossip. This should be sent on each new connection to
1019         /// enable receiving gossip messages from the peer.
1020         SendGossipTimestampFilter {
1021                 /// The node_id of this message recipient
1022                 node_id: PublicKey,
1023                 /// The gossip_timestamp_filter which should be sent.
1024                 msg: msgs::GossipTimestampFilter,
1025         },
1026 }
1027
1028 /// A trait indicating an object may generate message send events
1029 pub trait MessageSendEventsProvider {
1030         /// Gets the list of pending events which were generated by previous actions, clearing the list
1031         /// in the process.
1032         fn get_and_clear_pending_msg_events(&self) -> Vec<MessageSendEvent>;
1033 }
1034
1035 /// A trait indicating an object may generate events.
1036 ///
1037 /// Events are processed by passing an [`EventHandler`] to [`process_pending_events`].
1038 ///
1039 /// # Requirements
1040 ///
1041 /// See [`process_pending_events`] for requirements around event processing.
1042 ///
1043 /// When using this trait, [`process_pending_events`] will call [`handle_event`] for each pending
1044 /// event since the last invocation. The handler must either act upon the event immediately
1045 /// or preserve it for later handling.
1046 ///
1047 /// Note, handlers may call back into the provider and thus deadlocking must be avoided. Be sure to
1048 /// consult the provider's documentation on the implication of processing events and how a handler
1049 /// may safely use the provider (e.g., see [`ChannelManager::process_pending_events`] and
1050 /// [`ChainMonitor::process_pending_events`]).
1051 ///
1052 /// (C-not implementable) As there is likely no reason for a user to implement this trait on their
1053 /// own type(s).
1054 ///
1055 /// [`process_pending_events`]: Self::process_pending_events
1056 /// [`handle_event`]: EventHandler::handle_event
1057 /// [`ChannelManager::process_pending_events`]: crate::ln::channelmanager::ChannelManager#method.process_pending_events
1058 /// [`ChainMonitor::process_pending_events`]: crate::chain::chainmonitor::ChainMonitor#method.process_pending_events
1059 pub trait EventsProvider {
1060         /// Processes any events generated since the last call using the given event handler.
1061         ///
1062         /// Subsequent calls must only process new events. However, handlers must be capable of handling
1063         /// duplicate events across process restarts. This may occur if the provider was recovered from
1064         /// an old state (i.e., it hadn't been successfully persisted after processing pending events).
1065         fn process_pending_events<H: Deref>(&self, handler: H) where H::Target: EventHandler;
1066 }
1067
1068 /// A trait implemented for objects handling events from [`EventsProvider`].
1069 pub trait EventHandler {
1070         /// Handles the given [`Event`].
1071         ///
1072         /// See [`EventsProvider`] for details that must be considered when implementing this method.
1073         fn handle_event(&self, event: &Event);
1074 }
1075
1076 impl<F> EventHandler for F where F: Fn(&Event) {
1077         fn handle_event(&self, event: &Event) {
1078                 self(event)
1079         }
1080 }
1081
1082 impl<T: EventHandler> EventHandler for Arc<T> {
1083         fn handle_event(&self, event: &Event) {
1084                 self.deref().handle_event(event)
1085         }
1086 }