From 6bd0de257a70997065d51eee96c590610a7179ce Mon Sep 17 00:00:00 2001
From: carla <kirkcohenc@gmail.com>
Date: Wed, 19 Feb 2020 17:34:47 +0200
Subject: [PATCH] htlcswitch: notify incoming link failures

This commit adds link failure notifications for failures which occur
on our incoming link. These failures may be receives which we failed or
forwards which we could not parse.
---
 htlcswitch/link.go | 50 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 15 deletions(-)

diff --git a/htlcswitch/link.go b/htlcswitch/link.go
index c386ad345..5d5a30403 100644
--- a/htlcswitch/link.go
+++ b/htlcswitch/link.go
@@ -1224,8 +1224,7 @@ func (l *channelLink) processHtlcResolution(resolution invoices.HtlcResolution,
 		failure := getResolutionFailure(res, htlc.pd.Amount)
 
 		l.sendHTLCError(
-			htlc.pd.HtlcIndex, failure,
-			htlc.obfuscator, htlc.pd.SourceRef,
+			htlc.pd, failure, htlc.obfuscator, true,
 		)
 		return nil
 
@@ -2696,9 +2695,7 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 			// later date
 			failure := lnwire.NewInvalidOnionPayload(failedType, 0)
 			l.sendHTLCError(
-				pd.HtlcIndex,
-				NewLinkError(failure),
-				obfuscator, pd.SourceRef,
+				pd, NewLinkError(failure), obfuscator, false,
 			)
 
 			l.log.Errorf("unable to decode forwarding "+
@@ -2811,10 +2808,7 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 				)
 
 				l.sendHTLCError(
-					pd.HtlcIndex,
-					NewLinkError(failure),
-					obfuscator,
-					pd.SourceRef,
+					pd, NewLinkError(failure), obfuscator, false,
 				)
 				continue
 			}
@@ -2900,7 +2894,7 @@ func (l *channelLink) processExitHop(pd *lnwallet.PaymentDescriptor,
 		failure := NewLinkError(
 			lnwire.NewFinalIncorrectHtlcAmount(pd.Amount),
 		)
-		l.sendHTLCError(pd.HtlcIndex, failure, obfuscator, pd.SourceRef)
+		l.sendHTLCError(pd, failure, obfuscator, true)
 
 		return nil
 	}
@@ -2915,7 +2909,7 @@ func (l *channelLink) processExitHop(pd *lnwallet.PaymentDescriptor,
 		failure := NewLinkError(
 			lnwire.NewFinalIncorrectCltvExpiry(pd.Timeout),
 		)
-		l.sendHTLCError(pd.HtlcIndex, failure, obfuscator, pd.SourceRef)
+		l.sendHTLCError(pd, failure, obfuscator, true)
 
 		return nil
 	}
@@ -3031,8 +3025,8 @@ func (l *channelLink) handleBatchFwdErrs(errChan chan error) {
 
 // sendHTLCError functions cancels HTLC and send cancel message back to the
 // peer from which HTLC was received.
-func (l *channelLink) sendHTLCError(htlcIndex uint64, failure *LinkError,
-	e hop.ErrorEncrypter, sourceRef *channeldb.AddRef) {
+func (l *channelLink) sendHTLCError(pd *lnwallet.PaymentDescriptor,
+	failure *LinkError, e hop.ErrorEncrypter, isReceive bool) {
 
 	reason, err := e.EncryptFirstHop(failure.WireMessage())
 	if err != nil {
@@ -3040,7 +3034,7 @@ func (l *channelLink) sendHTLCError(htlcIndex uint64, failure *LinkError,
 		return
 	}
 
-	err = l.channel.FailHTLC(htlcIndex, reason, sourceRef, nil, nil)
+	err = l.channel.FailHTLC(pd.HtlcIndex, reason, pd.SourceRef, nil, nil)
 	if err != nil {
 		l.log.Errorf("unable cancel htlc: %v", err)
 		return
@@ -3048,9 +3042,35 @@ func (l *channelLink) sendHTLCError(htlcIndex uint64, failure *LinkError,
 
 	l.cfg.Peer.SendMessage(false, &lnwire.UpdateFailHTLC{
 		ChanID: l.ChanID(),
-		ID:     htlcIndex,
+		ID:     pd.HtlcIndex,
 		Reason: reason,
 	})
+
+	// Notify a link failure on our incoming link. Outgoing htlc information
+	// is not available at this point, because we have not decrypted the
+	// onion, so it is excluded.
+	var eventType HtlcEventType
+	if isReceive {
+		eventType = HtlcEventTypeReceive
+	} else {
+		eventType = HtlcEventTypeForward
+	}
+
+	l.cfg.HtlcNotifier.NotifyLinkFailEvent(
+		HtlcKey{
+			IncomingCircuit: channeldb.CircuitKey{
+				ChanID: l.ShortChanID(),
+				HtlcID: pd.HtlcIndex,
+			},
+		},
+		HtlcInfo{
+			IncomingTimeLock: pd.Timeout,
+			IncomingAmt:      pd.Amount,
+		},
+		eventType,
+		failure,
+		true,
+	)
 }
 
 // sendMalformedHTLCError helper function which sends the malformed HTLC update