Remove pending_inbound_payments map from ChannelManager

LDK versions prior to 0.0.104 had stateful inbound payments written in this
map. In 0.0.104, we added support for stateless inbound payments with
deterministically generated payment secrets, and maintained support for
stateful inbound payments until 0.0.116. After 0.0.116, no further inbound
payments could have been written into this map.

Author: valentinewallace

lightning/src/ln/channelmanager.rs

@@ -2166,25 +2166,23 @@ where
 //  |
 //  |__`per_peer_state`
 //      |
-//      |__`pending_inbound_payments`
-//          |
-//          |__`claimable_payments`
-//          |
-//          |__`pending_outbound_payments` // This field's struct contains a map of pending outbounds
-//              |
-//              |__`peer_state`
-//                  |
-//                  |__`outpoint_to_peer`
-//                  |
-//                  |__`short_to_chan_info`
-//                  |
-//                  |__`outbound_scid_aliases`
-//                  |
-//                  |__`best_block`
-//                  |
-//                  |__`pending_events`
-//                      |
-//                      |__`pending_background_events`
+//      |__`claimable_payments`
+//      |
+//      |__`pending_outbound_payments` // This field's struct contains a map of pending outbounds
+//         |
+//         |__`peer_state`
+//            |
+//            |__`outpoint_to_peer`
+//            |
+//            |__`short_to_chan_info`
+//            |
+//            |__`outbound_scid_aliases`
+//            |
+//            |__`best_block`
+//            |
+//            |__`pending_events`
+//               |
+//               |__`pending_background_events`
 //
 pub struct ChannelManager<M: Deref, T: Deref, ES: Deref, NS: Deref, SP: Deref, F: Deref, R: Deref, MR: Deref, L: Deref>
 where
@@ -2214,14 +2212,6 @@ where
 	best_block: RwLock<BestBlock>,
 	secp_ctx: Secp256k1<secp256k1::All>,
 
-	/// Storage for PaymentSecrets and any requirements on future inbound payments before we will
-	/// expose them to users via a PaymentClaimable event. HTLCs which do not meet the requirements
-	/// here are failed when we process them as pending-forwardable-HTLCs, and entries are removed
-	/// after we generate a PaymentClaimable upon receipt of all MPP parts or when they time out.
-	///
-	/// See `ChannelManager` struct-level documentation for lock order requirements.
-	pending_inbound_payments: Mutex<HashMap<PaymentHash, PendingInboundPayment>>,
-
 	/// The session_priv bytes and retry metadata of outbound payments which are pending resolution.
 	/// The authoritative state of these HTLCs resides either within Channels or ChannelMonitors
 	/// (if the channel has been force-closed), however we track them here to prevent duplicative
@@ -3217,7 +3207,6 @@ where
 			best_block: RwLock::new(params.best_block),
 
 			outbound_scid_aliases: Mutex::new(new_hash_set()),
-			pending_inbound_payments: Mutex::new(new_hash_map()),
 			pending_outbound_payments: OutboundPayments::new(new_hash_map()),
 			forward_htlcs: Mutex::new(new_hash_map()),
 			decode_update_add_htlcs: Mutex::new(new_hash_map()),
@@ -5896,66 +5885,36 @@ where
 								// that we are the ultimate recipient of the given payment hash.
 								// Further, we must not expose whether we have any other HTLCs
 								// associated with the same payment_hash pending or not.
-								let mut payment_secrets = self.pending_inbound_payments.lock().unwrap();
-								match payment_secrets.entry(payment_hash) {
-									hash_map::Entry::Vacant(_) => {
-										match claimable_htlc.onion_payload {
-											OnionPayload::Invoice { .. } => {
-												let payment_data = payment_data.unwrap();
-												let (payment_preimage, min_final_cltv_expiry_delta) = match inbound_payment::verify(payment_hash, &payment_data, self.highest_seen_timestamp.load(Ordering::Acquire) as u64, &self.inbound_payment_key, &self.logger) {
-													Ok(result) => result,
-													Err(()) => {
-														log_trace!(self.logger, "Failing new HTLC with payment_hash {} as payment verification failed", &payment_hash);
-														fail_htlc!(claimable_htlc, payment_hash);
-													}
-												};
-												if let Some(min_final_cltv_expiry_delta) = min_final_cltv_expiry_delta {
-													let expected_min_expiry_height = (self.current_best_block().height + min_final_cltv_expiry_delta as u32) as u64;
-													if (cltv_expiry as u64) < expected_min_expiry_height {
-														log_trace!(self.logger, "Failing new HTLC with payment_hash {} as its CLTV expiry was too soon (had {}, earliest expected {})",
-															&payment_hash, cltv_expiry, expected_min_expiry_height);
-														fail_htlc!(claimable_htlc, payment_hash);
-													}
-												}
-												let purpose = events::PaymentPurpose::from_parts(
-													payment_preimage,
-													payment_data.payment_secret,
-													payment_context,
-												);
-												check_total_value!(purpose);
-											},
-											OnionPayload::Spontaneous(preimage) => {
-												let purpose = events::PaymentPurpose::SpontaneousPayment(preimage);
-												check_total_value!(purpose);
-											}
-										}
-									},
-									hash_map::Entry::Occupied(inbound_payment) => {
-										if let OnionPayload::Spontaneous(_) = claimable_htlc.onion_payload {
-											log_trace!(self.logger, "Failing new keysend HTLC with payment_hash {} because we already have an inbound payment with the same payment hash", &payment_hash);
-											fail_htlc!(claimable_htlc, payment_hash);
-										}
+								match claimable_htlc.onion_payload {
+									OnionPayload::Invoice { .. } => {
 										let payment_data = payment_data.unwrap();
-										if inbound_payment.get().payment_secret != payment_data.payment_secret {
-											log_trace!(self.logger, "Failing new HTLC with payment_hash {} as it didn't match our expected payment secret.", &payment_hash);
-											fail_htlc!(claimable_htlc, payment_hash);
-										} else if inbound_payment.get().min_value_msat.is_some() && payment_data.total_msat < inbound_payment.get().min_value_msat.unwrap() {
-											log_trace!(self.logger, "Failing new HTLC with payment_hash {} as it didn't match our minimum value (had {}, needed {}).",
-												&payment_hash, payment_data.total_msat, inbound_payment.get().min_value_msat.unwrap());
-											fail_htlc!(claimable_htlc, payment_hash);
-										} else {
-											let purpose = events::PaymentPurpose::from_parts(
-												inbound_payment.get().payment_preimage,
-												payment_data.payment_secret,
-												payment_context,
-											);
-											let payment_claimable_generated = check_total_value!(purpose);
-											if payment_claimable_generated {
-												inbound_payment.remove_entry();
+										let (payment_preimage, min_final_cltv_expiry_delta) = match inbound_payment::verify(payment_hash, &payment_data, self.highest_seen_timestamp.load(Ordering::Acquire) as u64, &self.inbound_payment_key, &self.logger) {
+											Ok(result) => result,
+											Err(()) => {
+												log_trace!(self.logger, "Failing new HTLC with payment_hash {} as payment verification failed", &payment_hash);
+												fail_htlc!(claimable_htlc, payment_hash);
+											}
+										};
+										if let Some(min_final_cltv_expiry_delta) = min_final_cltv_expiry_delta {
+											let expected_min_expiry_height = (self.current_best_block().height + min_final_cltv_expiry_delta as u32) as u64;
+											if (cltv_expiry as u64) < expected_min_expiry_height {
+												log_trace!(self.logger, "Failing new HTLC with payment_hash {} as its CLTV expiry was too soon (had {}, earliest expected {})",
+												&payment_hash, cltv_expiry, expected_min_expiry_height);
+												fail_htlc!(claimable_htlc, payment_hash);
 											}
 										}
+										let purpose = events::PaymentPurpose::from_parts(
+											payment_preimage,
+											payment_data.payment_secret,
+											payment_context,
+										);
+										check_total_value!(purpose);
 									},
-								};
+									OnionPayload::Spontaneous(preimage) => {
+										let purpose = events::PaymentPurpose::SpontaneousPayment(preimage);
+										check_total_value!(purpose);
+									}
+								}
 							},
 							HTLCForwardInfo::FailHTLC { .. } | HTLCForwardInfo::FailMalformedHTLC { .. } => {
 								panic!("Got pending fail of our own HTLC");
@@ -10121,10 +10080,6 @@ where
 			}
 		}
 		max_time!(self.highest_seen_timestamp);
-		let mut payment_secrets = self.pending_inbound_payments.lock().unwrap();
-		payment_secrets.retain(|_, inbound_payment| {
-			inbound_payment.expiry_time > header.time as u64
-		});
 	}
 
 	fn get_relevant_txids(&self) -> Vec<(Txid, u32, Option<BlockHash>)> {
@@ -11873,7 +11828,6 @@ where
 			decode_update_add_htlcs_opt = Some(decode_update_add_htlcs);
 		}
 
-		let pending_inbound_payments = self.pending_inbound_payments.lock().unwrap();
 		let claimable_payments = self.claimable_payments.lock().unwrap();
 		let pending_outbound_payments = self.pending_outbound_payments.pending_outbound_payments.lock().unwrap();
 
@@ -11945,11 +11899,10 @@ where
 		(self.highest_seen_timestamp.load(Ordering::Acquire) as u32).write(writer)?;
 		(self.highest_seen_timestamp.load(Ordering::Acquire) as u32).write(writer)?;
 
-		(pending_inbound_payments.len() as u64).write(writer)?;
-		for (hash, pending_payment) in pending_inbound_payments.iter() {
-			hash.write(writer)?;
-			pending_payment.write(writer)?;
-		}
+		// LDK versions prior to 0.0.104 wrote `pending_inbound_payments` here, with deprecated support
+		// for stateful inbound payments maintained until 0.0.116, after which no further inbound
+		// payments could have been written here.
+		(0 as u64).write(writer)?;
 
 		// For backwards compat, write the session privs and their total length.
 		let mut num_pending_outbounds_compat: u64 = 0;
@@ -12463,13 +12416,9 @@ where
 		let _last_node_announcement_serial: u32 = Readable::read(reader)?; // Only used < 0.0.111
 		let highest_seen_timestamp: u32 = Readable::read(reader)?;
 
+		// The last version where a pending inbound payment may have been written was 0.0.116.
 		let pending_inbound_payment_count: u64 = Readable::read(reader)?;
-		let mut pending_inbound_payments: HashMap<PaymentHash, PendingInboundPayment> = hash_map_with_capacity(cmp::min(pending_inbound_payment_count as usize, MAX_ALLOC_SIZE/(3*32)));
-		for _ in 0..pending_inbound_payment_count {
-			if pending_inbound_payments.insert(Readable::read(reader)?, Readable::read(reader)?).is_some() {
-				return Err(DecodeError::InvalidValue);
-			}
-		}
+		if pending_inbound_payment_count != 0 { return Err(DecodeError::InvalidValue) }
 
 		let pending_outbound_payments_count_compat: u64 = Readable::read(reader)?;
 		let mut pending_outbound_payments_compat: HashMap<PaymentId, PendingOutboundPayment> =
@@ -12855,16 +12804,16 @@ where
 					OnionPayload::Invoice { _legacy_hop_data } => {
 						if let Some(hop_data) = _legacy_hop_data {
 							events::PaymentPurpose::Bolt11InvoicePayment {
-								payment_preimage: match pending_inbound_payments.get(&payment_hash) {
-									Some(inbound_payment) => inbound_payment.payment_preimage,
-									None => match inbound_payment::verify(payment_hash, &hop_data, 0, &expanded_inbound_key, &args.logger) {
+								payment_preimage:
+									match inbound_payment::verify(
+										payment_hash, &hop_data, 0, &expanded_inbound_key, &args.logger
+									) {
 										Ok((payment_preimage, _)) => payment_preimage,
 										Err(()) => {
 											log_error!(args.logger, "Failed to read claimable payment data for HTLC with payment hash {} - was not a pending inbound payment and didn't match our payment key", &payment_hash);
 											return Err(DecodeError::InvalidValue);
 										}
-									}
-								},
+									},
 								payment_secret: hop_data.payment_secret,
 							}
 						} else { return Err(DecodeError::InvalidValue); }
@@ -13043,7 +12992,6 @@ where
 			best_block: RwLock::new(BestBlock::new(best_block_hash, best_block_height)),
 
 			inbound_payment_key: expanded_inbound_key,
-			pending_inbound_payments: Mutex::new(pending_inbound_payments),
 			pending_outbound_payments: pending_outbounds,
 			pending_intercepted_htlcs: Mutex::new(pending_intercepted_htlcs.unwrap()),