record/hop: add primitive hop TLV record constructors

record/hop.go

@@ -0,0 +1,33 @@
+package record
+
+import (
+	"github.com/lightningnetwork/lnd/tlv"
+)
+
+// NewAmtToFwdRecord creates a tlv.Record that encodes the amount_to_forward
+// (type 2) for an onion payload.
+func NewAmtToFwdRecord(amt *uint64) tlv.Record {
+	return tlv.MakeDynamicRecord(
+		tlv.AmtOnionType, amt, func() uint64 {
+			return tlv.SizeTUint64(*amt)
+		},
+		tlv.ETUint64, tlv.DTUint64,
+	)
+}
+
+// NewLockTimeRecord creates a tlv.Record that encodes the outgoing_cltv_value
+// (type 4) for an onion payload.
+func NewLockTimeRecord(lockTime *uint32) tlv.Record {
+	return tlv.MakeDynamicRecord(
+		tlv.LockTimeOnionType, lockTime, func() uint64 {
+			return tlv.SizeTUint32(*lockTime)
+		},
+		tlv.ETUint32, tlv.DTUint32,
+	)
+}
+
+// NewNextHopIDRecord creates a tlv.Record that encodes the short_channel_id
+// (type 6) for an onion payload.
+func NewNextHopIDRecord(cid *uint64) tlv.Record {
+	return tlv.MakePrimitiveRecord(tlv.NextHopOnionType, cid)
+}