Merge pull request #1948 from alecchendev/custom-fail-back-err

[rust-lightning] / lightning / src / ln / channelmanager.rs

diff --git a/lightning/src/ln/channelmanager.rs b/lightning/src/ln/channelmanager.rs
index 17dcab9fe73323e9cea6f5cb04a7c16945591c7d..f99e4cf6ba5746f319f41c3638c1cfdb2db3f29d 100644 (file)
--- a/lightning/src/ln/channelmanager.rs
+++ b/lightning/src/ln/channelmanager.rs
@@ -289,6 +289,25 @@ struct ReceiveError {
        msg: &'static str,
 }
 
+/// This enum is used to specify which error data to send to peers when failing back an HTLC
+/// using [`ChannelManager::fail_htlc_backwards_with_reason`].
+///
+/// For more info on failure codes, see <https://github.com/lightning/bolts/blob/master/04-onion-routing.md#failure-messages>.
+#[derive(Clone, Copy)]
+pub enum FailureCode {
+       /// We had a temporary error processing the payment. Useful if no other error codes fit
+       /// and you want to indicate that the payer may want to retry.
+       TemporaryNodeFailure             = 0x2000 | 2,
+       /// We have a required feature which was not in this onion. For example, you may require
+       /// some additional metadata that was not provided with this payment.
+       RequiredNodeFeatureMissing       = 0x4000 | 0x2000 | 3,
+       /// You may wish to use this when a `payment_preimage` is unknown, or the CLTV expiry of
+       /// the HTLC is too close to the current block height for safe handling.
+       /// Using this failure code in [`ChannelManager::fail_htlc_backwards_with_reason`] is
+       /// equivalent to calling [`ChannelManager::fail_htlc_backwards`].
+       IncorrectOrUnknownPaymentDetails = 0x4000 | 15,
+}
+
 type ShutdownResult = (Option<(OutPoint, ChannelMonitorUpdate)>, Vec<(HTLCSource, PaymentHash, PublicKey, [u8; 32])>);
 
 /// Error type returned across the peer_state mutex boundary. When an Err is generated for a
@@ -3483,21 +3502,40 @@ where
        /// [`events::Event::PaymentClaimed`] events even for payments you intend to fail, especially on
        /// startup during which time claims that were in-progress at shutdown may be replayed.
        pub fn fail_htlc_backwards(&self, payment_hash: &PaymentHash) {
+               self.fail_htlc_backwards_with_reason(payment_hash, &FailureCode::IncorrectOrUnknownPaymentDetails);
+       }
+
+       /// This is a variant of [`ChannelManager::fail_htlc_backwards`] that allows you to specify the
+       /// reason for the failure.
+       ///
+       /// See [`FailureCode`] for valid failure codes.
+       pub fn fail_htlc_backwards_with_reason(&self, payment_hash: &PaymentHash, failure_code: &FailureCode) {
                let _persistence_guard = PersistenceNotifierGuard::notify_on_drop(&self.total_consistency_lock, &self.persistence_notifier);
 
                let removed_source = self.claimable_payments.lock().unwrap().claimable_htlcs.remove(payment_hash);
                if let Some((_, mut sources)) = removed_source {
                        for htlc in sources.drain(..) {
-                               let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
-                               htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height().to_be_bytes());
+                               let reason = self.get_htlc_fail_reason_from_failure_code(failure_code, &htlc);
                                let source = HTLCSource::PreviousHopData(htlc.prev_hop);
-                               let reason = HTLCFailReason::reason(0x4000 | 15, htlc_msat_height_data);
                                let receiver = HTLCDestination::FailedPayment { payment_hash: *payment_hash };
                                self.fail_htlc_backwards_internal(&source, &payment_hash, &reason, receiver);
                        }
                }
        }
 
+       /// Gets error data to form an [`HTLCFailReason`] given a [`FailureCode`] and [`ClaimableHTLC`].
+       fn get_htlc_fail_reason_from_failure_code(&self, failure_code: &FailureCode, htlc: &ClaimableHTLC) -> HTLCFailReason {
+               match failure_code {
+                       FailureCode::TemporaryNodeFailure => HTLCFailReason::from_failure_code(*failure_code as u16),
+                       FailureCode::RequiredNodeFeatureMissing => HTLCFailReason::from_failure_code(*failure_code as u16),
+                       FailureCode::IncorrectOrUnknownPaymentDetails => {
+                               let mut htlc_msat_height_data = htlc.value.to_be_bytes().to_vec();
+                               htlc_msat_height_data.extend_from_slice(&self.best_block.read().unwrap().height().to_be_bytes());
+                               HTLCFailReason::reason(*failure_code as u16, htlc_msat_height_data)
+                       }
+               }
+       }
+
        /// Gets an HTLC onion failure code and error data for an `UPDATE` error, given the error code
        /// that we want to return and a channel.
        ///