ln: expand LocalHTLCFailureReason to un-erase BOLT04 error codes

Sometimes the error codes that we return to the sender intentionally
obscure information about the payment to prevent probing/ leaking
information. This commit updates our internal representation to
surface some of these failures, which will be converted to their
corresponding bolt 04 codes when they're sent over the wire.

Author: carlaKC

lightning/src/ln/channel.rs

@@ -7887,7 +7887,7 @@ impl<SP: Deref> FundedChannel<SP> where
 		L::Target: Logger
 	{
 		if self.context.channel_state.is_local_shutdown_sent() {
-			return Err(("Shutdown was already sent", LocalHTLCFailureReason::PermanentChannelFailure))
+			return Err(("Shutdown was already sent", LocalHTLCFailureReason::ChannelClosed))
 		}
 
 		let dust_exposure_limiting_feerate = self.context.get_dust_exposure_limiting_feerate(&fee_estimator);
@@ -7899,7 +7899,7 @@ impl<SP: Deref> FundedChannel<SP> where
 			log_info!(logger, "Cannot accept value that would put our total dust exposure at {} over the limit {} on counterparty commitment tx",
 				on_counterparty_tx_dust_htlc_exposure_msat, max_dust_htlc_exposure_msat);
 			return Err(("Exceeded our total dust exposure limit on counterparty commitment tx",
-				LocalHTLCFailureReason::TemporaryChannelFailure))
+				LocalHTLCFailureReason::DustLimitCounterparty))
 		}
 		let htlc_success_dust_limit = if self.funding.get_channel_type().supports_anchors_zero_fee_htlc_tx() {
 			0
@@ -7914,7 +7914,7 @@ impl<SP: Deref> FundedChannel<SP> where
 				log_info!(logger, "Cannot accept value that would put our exposure to dust HTLCs at {} over the limit {} on holder commitment tx",
 					on_holder_tx_dust_htlc_exposure_msat, max_dust_htlc_exposure_msat);
 				return Err(("Exceeded our dust exposure limit on holder commitment tx",
-					LocalHTLCFailureReason::TemporaryChannelFailure))
+					LocalHTLCFailureReason::DustLimitHolder))
 			}
 		}
 
@@ -7952,7 +7952,7 @@ impl<SP: Deref> FundedChannel<SP> where
 			}
 			if pending_remote_value_msat.saturating_sub(self.funding.holder_selected_channel_reserve_satoshis * 1000).saturating_sub(anchor_outputs_value_msat) < remote_fee_cost_incl_stuck_buffer_msat {
 				log_info!(logger, "Attempting to fail HTLC due to fee spike buffer violation in channel {}. Rebalancing is required.", &self.context.channel_id());
-				return Err(("Fee spike buffer violation", LocalHTLCFailureReason::TemporaryChannelFailure));
+				return Err(("Fee spike buffer violation", LocalHTLCFailureReason::FeeSpikeBuffer));
 			}
 		}
 

lightning/src/ln/channelmanager.rs

@@ -3923,7 +3923,7 @@ where
 		}
 
 		for htlc_source in failed_htlcs.drain(..) {
-			let failure_reason = LocalHTLCFailureReason::PermanentChannelFailure;
+			let failure_reason = LocalHTLCFailureReason::ChannelClosed;
 			let reason = HTLCFailReason::from_failure_code(failure_reason);
 			let receiver = HTLCDestination::NextHopChannel { node_id: Some(*counterparty_node_id), channel_id: *channel_id };
 			self.fail_htlc_backwards_internal(&htlc_source.0, &htlc_source.1, &reason, receiver);
@@ -4047,7 +4047,7 @@ where
 			shutdown_res.closure_reason, shutdown_res.dropped_outbound_htlcs.len());
 		for htlc_source in shutdown_res.dropped_outbound_htlcs.drain(..) {
 			let (source, payment_hash, counterparty_node_id, channel_id) = htlc_source;
-			let failure_reason = LocalHTLCFailureReason::PermanentChannelFailure;
+			let failure_reason = LocalHTLCFailureReason::ChannelClosed;
 			let reason = HTLCFailReason::from_failure_code(failure_reason);
 			let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id };
 			self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
@@ -4350,19 +4350,19 @@ where
 			// should NOT reveal the existence or non-existence of a private channel if
 			// we don't allow forwards outbound over them.
 			return Err(("Refusing to forward to a private channel based on our config.",
-				LocalHTLCFailureReason::UnknownNextPeer));
+				LocalHTLCFailureReason::PrivateChannelForward));
 		}
 		if let HopConnector::ShortChannelId(outgoing_scid) = next_packet.outgoing_connector {
 			if chan.funding.get_channel_type().supports_scid_privacy() && outgoing_scid != chan.context.outbound_scid_alias() {
 				// `option_scid_alias` (referred to in LDK as `scid_privacy`) means
 				// "refuse to forward unless the SCID alias was used", so we pretend
 				// we don't have the channel here.
 				return Err(("Refusing to forward over real channel SCID as our counterparty requested.",
-					LocalHTLCFailureReason::UnknownNextPeer));
+					LocalHTLCFailureReason::RealSCIDForward));
 			}
 		} else {
 			return Err(("Cannot forward by Node ID without SCID.",
-				LocalHTLCFailureReason::UnknownNextPeer));
+				LocalHTLCFailureReason::InvalidTrampolineForward));
 		}
 
 		// Note that we could technically not return an error yet here and just hope
@@ -4376,7 +4376,7 @@ where
 					LocalHTLCFailureReason::ChannelDisabled));
 			} else {
 				return Err(("Forwarding channel is not in a ready state.",
-					LocalHTLCFailureReason::TemporaryChannelFailure));
+					LocalHTLCFailureReason::ChannelNotReady));
 			}
 		}
 		if next_packet.outgoing_amt_msat < chan.context.get_counterparty_htlc_minimum_msat() {
@@ -4417,7 +4417,7 @@ where
 			HopConnector::ShortChannelId(scid) => scid,
 			HopConnector::Trampoline(_) => {
 				return Err(("Cannot forward by Node ID without SCID.",
-				LocalHTLCFailureReason::UnknownNextPeer));
+				LocalHTLCFailureReason::InvalidTrampolineForward));
 			}
 		};
 		match self.do_funded_channel_callback(outgoing_scid, |chan: &mut FundedChannel<SP>| {
@@ -8773,7 +8773,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 		}
 		for htlc_source in dropped_htlcs.drain(..) {
 			let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id.clone()), channel_id: msg.channel_id };
-			let reason = HTLCFailReason::from_failure_code(LocalHTLCFailureReason::PermanentChannelFailure);
+			let reason = HTLCFailReason::from_failure_code(LocalHTLCFailureReason::ChannelClosed);
 			self.fail_htlc_backwards_internal(&htlc_source.0, &htlc_source.1, &reason, receiver);
 		}
 		if let Some(shutdown_res) = finish_shutdown {
@@ -9629,7 +9629,7 @@ This indicates a bug inside LDK. Please report this error at https://github.com/
 							);
 						} else {
 							log_trace!(logger, "Failing HTLC with hash {} from our monitor", &htlc_update.payment_hash);
-							let failure_reason = LocalHTLCFailureReason::PermanentChannelFailure;
+							let failure_reason = LocalHTLCFailureReason::OnChainTimeout;
 							let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id };
 							let reason = HTLCFailReason::from_failure_code(failure_reason);
 							self.fail_htlc_backwards_internal(&htlc_update.source, &htlc_update.payment_hash, &reason, receiver);
@@ -11828,7 +11828,7 @@ where
 					// number of blocks we generally consider it to take to do a commitment update,
 					// just give up on it and fail the HTLC.
 					if height >= htlc.cltv_expiry - HTLC_FAIL_BACK_BUFFER {
-						let reason = LocalHTLCFailureReason::IncorrectPaymentDetails;
+						let reason = LocalHTLCFailureReason::PaymentClaimBuffer;
 						timed_out_htlcs.push((HTLCSource::PreviousHopData(htlc.prev_hop.clone()), payment_hash.clone(),
 							HTLCFailReason::reason(reason, invalid_payment_err_data(htlc.value, height)),
 							HTLCDestination::FailedPayment { payment_hash: payment_hash.clone() }));
@@ -11859,7 +11859,7 @@ where
 						_ => unreachable!(),
 					};
 					timed_out_htlcs.push((prev_hop_data, htlc.forward_info.payment_hash,
-							HTLCFailReason::from_failure_code(LocalHTLCFailureReason::TemporaryNodeFailure),
+							HTLCFailReason::from_failure_code(LocalHTLCFailureReason::ForwardExpiryBuffer),
 							HTLCDestination::InvalidForward { requested_forward_scid }));
 					let logger = WithContext::from(
 						&self.logger, None, Some(htlc.prev_channel_id), Some(htlc.forward_info.payment_hash)
@@ -14948,7 +14948,7 @@ where
 
 		for htlc_source in failed_htlcs.drain(..) {
 			let (source, payment_hash, counterparty_node_id, channel_id) = htlc_source;
-			let failure_reason = LocalHTLCFailureReason::PermanentChannelFailure;
+			let failure_reason = LocalHTLCFailureReason::ChannelClosed;
 			let receiver = HTLCDestination::NextHopChannel { node_id: Some(counterparty_node_id), channel_id };
 			let reason = HTLCFailReason::from_failure_code(failure_reason);
 			channel_manager.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);

lightning/src/ln/onion_payment.rs

@@ -199,7 +199,7 @@ pub(super) fn create_fwd_pending_htlc_info(
 				Some(Ok(pubkey)) => pubkey,
 				_ => return Err(InboundHTLCErr {
 					msg: "Missing next Trampoline hop pubkey from intermediate Trampoline forwarding data",
-					reason: LocalHTLCFailureReason::InvalidOnionPayload,
+					reason: LocalHTLCFailureReason::InvalidTrampolinePayload,
 					err_data: Vec::new(),
 				}),
 			};
@@ -342,7 +342,7 @@ pub(super) fn create_recv_pending_htlc_info(
 	// channel closure (see HTLC_FAIL_BACK_BUFFER rationale).
 	if cltv_expiry <= current_height + HTLC_FAIL_BACK_BUFFER + 1 {
 		return Err(InboundHTLCErr {
-			reason: LocalHTLCFailureReason::IncorrectPaymentDetails,
+			reason: LocalHTLCFailureReason::PaymentClaimBuffer,
 			err_data: invalid_payment_err_data(amt_msat, current_height),
 			msg: "The final CLTV expiry is too soon to handle",
 		});
@@ -367,7 +367,7 @@ pub(super) fn create_recv_pending_htlc_info(
 		let hashed_preimage = PaymentHash(Sha256::hash(&payment_preimage.0).to_byte_array());
 		if hashed_preimage != payment_hash {
 			return Err(InboundHTLCErr {
-				reason: LocalHTLCFailureReason::IncorrectPaymentDetails,
+				reason: LocalHTLCFailureReason::InvalidKeysendPreimage,
 				err_data: invalid_payment_err_data(amt_msat, current_height),
 				msg: "Payment preimage didn't match payment hash",
 			});
@@ -395,7 +395,7 @@ pub(super) fn create_recv_pending_htlc_info(
 		}
 	} else {
 		return Err(InboundHTLCErr {
-			reason: LocalHTLCFailureReason::RequiredNodeFeature,
+			reason: LocalHTLCFailureReason::PaymentSecretRequired,
 			err_data: Vec::new(),
 			msg: "We require payment_secrets",
 		});
@@ -624,7 +624,7 @@ pub(super) fn check_incoming_htlc_cltv(
 	// but there is no need to do that, and since we're a bit conservative with our
 	// risk threshold it just results in failing to forward payments.
 	if (outgoing_cltv_value) as u64 <= (cur_height + LATENCY_GRACE_PERIOD_BLOCKS) as u64 {
-		return Err(("Outgoing CLTV value is too soon", LocalHTLCFailureReason::CLTVExpiryTooSoon));
+		return Err(("Outgoing CLTV value is too soon", LocalHTLCFailureReason::OutgoingCLTVTooSoon));
 	}
 
 	Ok(())