From 74db43282ce532a2f5aa49779dd5ef1a8c7c1347 Mon Sep 17 00:00:00 2001
From: Joost Jager <joost.jager@gmail.com>
Date: Tue, 23 Jun 2020 16:19:41 +0200
Subject: [PATCH] htlcswitch: encapsulate exposed packet info

---
 htlcswitch/interceptable_switch.go     | 18 +++++++++---------
 htlcswitch/interfaces.go               | 23 +++++++++++++++++++----
 lnrpc/routerrpc/forward_interceptor.go | 10 +++++-----
 3 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/htlcswitch/interceptable_switch.go b/htlcswitch/interceptable_switch.go
index cdf5bae0..2ca54e42 100644
--- a/htlcswitch/interceptable_switch.go
+++ b/htlcswitch/interceptable_switch.go
@@ -115,15 +115,15 @@ type interceptedForward struct {
 }
 
 // Packet returns the intercepted htlc packet.
-func (f *interceptedForward) Packet() lnwire.UpdateAddHTLC {
-	return *f.htlc
-}
-
-// CircuitKey returns the circuit key for the intercepted htlc.
-func (f *interceptedForward) CircuitKey() channeldb.CircuitKey {
-	return channeldb.CircuitKey{
-		ChanID: f.packet.incomingChanID,
-		HtlcID: f.packet.incomingHTLCID,
+func (f *interceptedForward) Packet() InterceptedPacket {
+	return InterceptedPacket{
+		IncomingCircuit: channeldb.CircuitKey{
+			ChanID: f.packet.incomingChanID,
+			HtlcID: f.packet.incomingHTLCID,
+		},
+		Hash:           f.htlc.PaymentHash,
+		OutgoingExpiry: f.htlc.Expiry,
+		OutgoingAmount: f.htlc.Amount,
 	}
 }
 
diff --git a/htlcswitch/interfaces.go b/htlcswitch/interfaces.go
index 67b1a458..74b1a568 100644
--- a/htlcswitch/interfaces.go
+++ b/htlcswitch/interfaces.go
@@ -200,17 +200,32 @@ type InterceptableHtlcForwarder interface {
 // and resolve it later or let the switch execute its default behavior.
 type ForwardInterceptor func(InterceptedForward) bool
 
+// InterceptedPacket contains the relevant information for the interceptor about
+// an htlc.
+type InterceptedPacket struct {
+	// IncomingCircuit contains the incoming channel and htlc id of the
+	// packet.
+	IncomingCircuit channeldb.CircuitKey
+
+	// Hash is the payment hash of the htlc.
+	Hash lntypes.Hash
+
+	// OutgoingExpiry is the absolute block height at which the outgoing
+	// htlc expires.
+	OutgoingExpiry uint32
+
+	// OutgoingAmount is the amount to forward.
+	OutgoingAmount lnwire.MilliSatoshi
+}
+
 // InterceptedForward is passed to the ForwardInterceptor for every forwarded
 // htlc. It contains all the information about the packet which accordingly
 // the interceptor decides if to hold or not.
 // In addition this interface allows a later resolution by calling either
 // Resume, Settle or Fail.
 type InterceptedForward interface {
-	// CircuitKey returns the intercepted packet.
-	CircuitKey() channeldb.CircuitKey
-
 	// Packet returns the intercepted packet.
-	Packet() lnwire.UpdateAddHTLC
+	Packet() InterceptedPacket
 
 	// Resume notifies the intention to resume an existing hold forward. This
 	// basically means the caller wants to resume with the default behavior for
diff --git a/lnrpc/routerrpc/forward_interceptor.go b/lnrpc/routerrpc/forward_interceptor.go
index 9844c572..00db973d 100644
--- a/lnrpc/routerrpc/forward_interceptor.go
+++ b/lnrpc/routerrpc/forward_interceptor.go
@@ -148,18 +148,18 @@ func (r *forwardInterceptor) holdAndForwardToClient(
 	forward htlcswitch.InterceptedForward) error {
 
 	htlc := forward.Packet()
-	inKey := forward.CircuitKey()
+	inKey := htlc.IncomingCircuit
 
 	// First hold the forward, then send to client.
-	r.holdForwards[forward.CircuitKey()] = forward
+	r.holdForwards[inKey] = forward
 	interceptionRequest := &ForwardHtlcInterceptRequest{
 		IncomingCircuitKey: &CircuitKey{
 			ChanId: inKey.ChanID.ToUint64(),
 			HtlcId: inKey.HtlcID,
 		},
-		PaymentHash:        htlc.PaymentHash[:],
-		OutgoingAmountMsat: uint64(htlc.Amount),
-		OutgoingExpiry:     htlc.Expiry,
+		PaymentHash:        htlc.Hash[:],
+		OutgoingAmountMsat: uint64(htlc.OutgoingAmount),
+		OutgoingExpiry:     htlc.OutgoingExpiry,
 	}
 
 	return r.stream.Send(interceptionRequest)