Fix Bolt12 path fee hiding

eclair-core/src/main/resources/reference.conf

@@ -734,11 +734,10 @@ eclair {
   offers {
     // Minimum length of an offer blinded path when hiding our real node id
     message-path-min-length = 2
-
     // Number of payment paths to put in Bolt12 invoices when hiding our real node id
     payment-path-count = 2
     // Length of payment paths to put in Bolt12 invoices when hiding our real node id
-    payment-path-length = 4
+    payment-path-length = 2
     // Expiry delta of payment paths to put in Bolt12 invoices when hiding our real node id
     payment-path-expiry-delta = 500
   }

eclair-core/src/main/scala/fr/acinq/eclair/payment/offer/OfferManager.scala

@@ -285,7 +285,7 @@ object OfferManager {
             val minimalInvoice = MinimalBolt12Invoice(offer, nodeParams.chainHash, metadata.amount, metadata.quantity, Crypto.sha256(metadata.preimage), metadata.payerKey, metadata.createdAt, additionalTlvs, customTlvs)
             val incomingPayment = IncomingBlindedPayment(minimalInvoice, metadata.preimage, PaymentType.Blinded, TimestampMilli.now(), IncomingPaymentStatus.Pending)
             // We may be deducing some of the blinded path fees from the received amount.
-            val maxRecipientPathFees = nodeFee(metadata.recipientPathFees, amount)
+            val maxRecipientPathFees = nodeFee(metadata.recipientPathFees, Seq(amount, metadata.amount).max)
             replyTo ! MultiPartHandler.GetIncomingPaymentActor.ProcessPayment(incomingPayment, maxRecipientPathFees)
             Behaviors.stopped
           case RejectPayment(reason) =>

eclair-core/src/test/scala/fr/acinq/eclair/integration/basic/payment/OfferPaymentSpec.scala

@@ -783,7 +783,7 @@ class OfferPaymentSpec extends FixtureSpec with IntegrationPatience {
     assert(offer.nodeId.isEmpty)
     assert(offer.contactInfos.size == 1)
     assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.firstNodeId == EncodedNodeId.WithPublicKey.Plain(carol.nodeId))
-    assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.length == carol.nodeParams.offersConfig.messagePathMinLength)
+    assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.length >= carol.nodeParams.offersConfig.messagePathMinLength)
     assert(offer.description.contains("test offer"))
     assert(offer.amount.contains(amount))
 
@@ -801,7 +801,7 @@ class OfferPaymentSpec extends FixtureSpec with IntegrationPatience {
     assert(offer.nodeId.isEmpty)
     assert(offer.contactInfos.size == 1)
     assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.firstNodeId == EncodedNodeId.WithPublicKey.Plain(bob.nodeId))
-    assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.length == carol.nodeParams.offersConfig.messagePathMinLength)
+    assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.length >= carol.nodeParams.offersConfig.messagePathMinLength)
     assert(offer.description.contains("test offer"))
     assert(offer.amount.contains(amount))
 
@@ -825,7 +825,7 @@ class OfferPaymentSpec extends FixtureSpec with IntegrationPatience {
     val offer = createOffer(carol, description_opt = Some("test offer"), amount_opt = Some(amount), issuer_opt = None, blindedPathsFirstNodeId_opt = Some(alice.nodeId))
     assert(offer.nodeId.isEmpty)
     assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.firstNodeId == EncodedNodeId.WithPublicKey.Plain(alice.nodeId))
-    assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.length == carol.nodeParams.offersConfig.messagePathMinLength)
+    assert(offer.contactInfos.head.asInstanceOf[BlindedPath].route.length >= carol.nodeParams.offersConfig.messagePathMinLength)
     assert(offer.description.contains("test offer"))
     assert(offer.amount.contains(amount))
 

eclair-core/src/test/scala/fr/acinq/eclair/payment/offer/OfferManagerSpec.scala

@@ -33,7 +33,7 @@ import fr.acinq.eclair.router.Router.ChannelHop
 import fr.acinq.eclair.wire.protocol.OfferTypes.{InvoiceRequest, Offer}
 import fr.acinq.eclair.wire.protocol.RouteBlindingEncryptedDataCodecs.RouteBlindingDecryptedData
 import fr.acinq.eclair.wire.protocol._
-import fr.acinq.eclair.{CltvExpiry, CltvExpiryDelta, Features, MilliSatoshi, MilliSatoshiLong, NodeParams, TestConstants, amountAfterFee, randomBytes32, randomKey}
+import fr.acinq.eclair.{CltvExpiry, CltvExpiryDelta, Features, MilliSatoshi, MilliSatoshiLong, NodeParams, TestConstants, amountAfterFee, nodeFee, randomBytes32, randomKey}
 import org.scalatest.funsuite.FixtureAnyFunSuiteLike
 import org.scalatest.{Outcome, Tag}
 import scodec.bits.{ByteVector, HexStringSyntax}
@@ -332,6 +332,7 @@ class OfferManagerSpec extends ScalaTestWithActorTestKit(ConfigFactory.load("app
     assert(Crypto.sha256(incomingPayment.paymentPreimage) == invoice.paymentHash)
     assert(incomingPayment.invoice.nodeId == nodeParams.nodeId)
     assert(incomingPayment.invoice.paymentHash == invoice.paymentHash)
-    assert(maxRecipientPathFees == paymentPayload.amount - amountReceived)
+    assert(maxRecipientPathFees >= paymentPayload.amount - amountReceived)
+    assert(maxRecipientPathFees == nodeFee(1000 msat, 200, amount))
   }
 }