Add a separate PaymentSendFailure for idempotency violation

fuzz/src/chanmon_consistency.rs

@@ -283,12 +283,13 @@ fn check_payment_err(send_err: PaymentSendFailure) {
 		PaymentSendFailure::PathParameterError(per_path_results) => {
 			for res in per_path_results { if let Err(api_err) = res { check_api_err(api_err); } }
 		},
-		PaymentSendFailure::AllFailedRetrySafe(per_path_results) => {
+		PaymentSendFailure::AllFailedResendSafe(per_path_results) => {
 			for api_err in per_path_results { check_api_err(api_err); }
 		},
 		PaymentSendFailure::PartialFailure { results, .. } => {
 			for res in results { if let Err(api_err) = res { check_api_err(api_err); } }
 		},
+		PaymentSendFailure::DuplicatePayment => panic!(),
 	}
 }
 

lightning-invoice/src/payment.rs

@@ -543,7 +543,8 @@ where
 			Err(e) => match e {
 				PaymentSendFailure::ParameterError(_) => Err(e),
 				PaymentSendFailure::PathParameterError(_) => Err(e),
-				PaymentSendFailure::AllFailedRetrySafe(_) => {
+				PaymentSendFailure::DuplicatePayment => Err(e),
+				PaymentSendFailure::AllFailedResendSafe(_) => {
 					let mut payment_cache = self.payment_cache.lock().unwrap();
 					let payment_info = payment_cache.get_mut(&payment_hash).unwrap();
 					payment_info.attempts.count += 1;
@@ -655,9 +656,13 @@ where
 				log_trace!(self.logger, "Failed to retry for payment {} due to bogus route/payment data, not retrying.", log_bytes!(payment_hash.0));
 				Err(())
 			},
-			Err(PaymentSendFailure::AllFailedRetrySafe(_)) => {
+			Err(PaymentSendFailure::AllFailedResendSafe(_)) => {
 				self.retry_payment(payment_id, payment_hash, params)
 			},
+			Err(PaymentSendFailure::DuplicatePayment) => {
+				log_error!(self.logger, "Got a DuplicatePayment error when attempting to retry a payment, this shouldn't happen.");
+				Err(())
+			}
 			Err(PaymentSendFailure::PartialFailure { failed_paths_retry, results, .. }) => {
 				// If a `PartialFailure` error contains a result that is an `Ok()`, it means that
 				// part of our payment is retried. When we receive `MonitorUpdateInProgress`, it

lightning/src/ln/channelmanager.rs

@@ -1188,24 +1188,40 @@ impl ChannelDetails {
 #[derive(Clone, Debug)]
 pub enum PaymentSendFailure {
 	/// A parameter which was passed to send_payment was invalid, preventing us from attempting to
-	/// send the payment at all. No channel state has been changed or messages sent to peers, and
-	/// once you've changed the parameter at error, you can freely retry the payment in full.
+	/// send the payment at all.
+	///
+	/// You can freely resend the payment in full (with the parameter error fixed).
+	///
+	/// Because the payment failed outright, no payment tracking is done, you do not need to call
+	/// [`ChannelManager::abandon_payment`] and [`ChannelManager::retry_payment`] will *not* work
+	/// for this payment.
 	ParameterError(APIError),
 	/// A parameter in a single path which was passed to send_payment was invalid, preventing us
-	/// from attempting to send the payment at all. No channel state has been changed or messages
-	/// sent to peers, and once you've changed the parameter at error, you can freely retry the
-	/// payment in full.
+	/// from attempting to send the payment at all.
+	///
+	/// You can freely resend the payment in full (with the parameter error fixed).
 	///
 	/// The results here are ordered the same as the paths in the route object which was passed to
 	/// send_payment.
+	///
+	/// Because the payment failed outright, no payment tracking is done, you do not need to call
+	/// [`ChannelManager::abandon_payment`] and [`ChannelManager::retry_payment`] will *not* work
+	/// for this payment.
 	PathParameterError(Vec<Result<(), APIError>>),
 	/// All paths which were attempted failed to send, with no channel state change taking place.
-	/// You can freely retry the payment in full (though you probably want to do so over different
+	/// You can freely resend the payment in full (though you probably want to do so over different
 	/// paths than the ones selected).
 	///
-	/// [`ChannelManager::abandon_payment`] does *not* need to be called for this payment and
-	/// [`ChannelManager::retry_payment`] will *not* work for this payment.
-	AllFailedRetrySafe(Vec<APIError>),
+	/// Because the payment failed outright, no payment tracking is done, you do not need to call
+	/// [`ChannelManager::abandon_payment`] and [`ChannelManager::retry_payment`] will *not* work
+	/// for this payment.
+	AllFailedResendSafe(Vec<APIError>),
+	/// Indicates that a payment for the provided [`PaymentId`] is already in-flight and has not
+	/// yet completed (i.e. generated an [`Event::PaymentSent`]) or been abandoned (via
+	/// [`ChannelManager::abandon_payment`]).
+	///
+	/// [`Event::PaymentSent`]: events::Event::PaymentSent
+	DuplicatePayment,
 	/// Some paths which were attempted failed to send, though possibly not all. At least some
 	/// paths have irrevocably committed to the HTLC and retrying the payment in full would result
 	/// in over-/re-payment.
@@ -2610,9 +2626,7 @@ impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F
 
 		let mut pending_outbounds = self.pending_outbound_payments.lock().unwrap();
 		match pending_outbounds.entry(payment_id) {
-			hash_map::Entry::Occupied(_) => Err(PaymentSendFailure::ParameterError(APIError::RouteError {
-				err: "Payment already in progress"
-			})),
+			hash_map::Entry::Occupied(_) => Err(PaymentSendFailure::DuplicatePayment),
 			hash_map::Entry::Vacant(entry) => {
 				let payment = entry.insert(PendingOutboundPayment::Retryable {
 					session_privs: HashSet::new(),
@@ -2726,7 +2740,7 @@ impl<M: Deref, T: Deref, K: Deref, F: Deref, L: Deref> ChannelManager<M, T, K, F
 			// `pending_outbound_payments` map, as the user isn't expected to `abandon_payment`.
 			let removed = self.pending_outbound_payments.lock().unwrap().remove(&payment_id).is_some();
 			debug_assert!(removed, "We should always have a pending payment to remove here");
-			Err(PaymentSendFailure::AllFailedRetrySafe(results.drain(..).map(|r| r.unwrap_err()).collect()))
+			Err(PaymentSendFailure::AllFailedResendSafe(results.drain(..).map(|r| r.unwrap_err()).collect()))
 		} else {
 			Ok(())
 		}

lightning/src/ln/functional_test_utils.rs

@@ -587,7 +587,7 @@ macro_rules! get_local_commitment_txn {
 macro_rules! unwrap_send_err {
 	($res: expr, $all_failed: expr, $type: pat, $check: expr) => {
 		match &$res {
-			&Err(PaymentSendFailure::AllFailedRetrySafe(ref fails)) if $all_failed => {
+			&Err(PaymentSendFailure::AllFailedResendSafe(ref fails)) if $all_failed => {
 				assert_eq!(fails.len(), 1);
 				match fails[0] {
 					$type => { $check },

lightning/src/ln/functional_tests.rs

@@ -1333,7 +1333,7 @@ fn test_basic_channel_reserve() {
 	let (route, our_payment_hash, _, our_payment_secret) = get_route_and_payment_hash!(nodes[0], nodes[1], max_can_send + 1);
 	let err = nodes[0].node.send_payment(&route, our_payment_hash, &Some(our_payment_secret), PaymentId(our_payment_hash.0)).err().unwrap();
 	match err {
-		PaymentSendFailure::AllFailedRetrySafe(ref fails) => {
+		PaymentSendFailure::AllFailedResendSafe(ref fails) => {
 			match &fails[0] {
 				&APIError::ChannelUnavailable{ref err} =>
 					assert!(regex::Regex::new(r"Cannot send value that would put our balance under counterparty-announced channel reserve value \(\d+\)").unwrap().is_match(err)),

lightning/src/ln/payment_tests.rs

@@ -1275,15 +1275,15 @@ fn claimed_send_payment_idempotent() {
 			// payment_id, it should be rejected.
 			let send_result = nodes[0].node.send_payment(&route, second_payment_hash, &Some(second_payment_secret), payment_id);
 			match send_result {
-				Err(PaymentSendFailure::ParameterError(APIError::RouteError { err: "Payment already in progress" })) => {},
+				Err(PaymentSendFailure::DuplicatePayment) => {},
 				_ => panic!("Unexpected send result: {:?}", send_result),
 			}
 
 			// Further, if we try to send a spontaneous payment with the same payment_id it should
 			// also be rejected.
 			let send_result = nodes[0].node.send_spontaneous_payment(&route, None, payment_id);
 			match send_result {
-				Err(PaymentSendFailure::ParameterError(APIError::RouteError { err: "Payment already in progress" })) => {},
+				Err(PaymentSendFailure::DuplicatePayment) => {},
 				_ => panic!("Unexpected send result: {:?}", send_result),
 			}
 		}
@@ -1347,15 +1347,15 @@ fn abandoned_send_payment_idempotent() {
 			// payment_id, it should be rejected.
 			let send_result = nodes[0].node.send_payment(&route, second_payment_hash, &Some(second_payment_secret), payment_id);
 			match send_result {
-				Err(PaymentSendFailure::ParameterError(APIError::RouteError { err: "Payment already in progress" })) => {},
+				Err(PaymentSendFailure::DuplicatePayment) => {},
 				_ => panic!("Unexpected send result: {:?}", send_result),
 			}
 
 			// Further, if we try to send a spontaneous payment with the same payment_id it should
 			// also be rejected.
 			let send_result = nodes[0].node.send_spontaneous_payment(&route, None, payment_id);
 			match send_result {
-				Err(PaymentSendFailure::ParameterError(APIError::RouteError { err: "Payment already in progress" })) => {},
+				Err(PaymentSendFailure::DuplicatePayment) => {},
 				_ => panic!("Unexpected send result: {:?}", send_result),
 			}
 		}