Validate compact offer

Author: thomash-acinq

modules/core/src/commonMain/kotlin/fr/acinq/lightning/payment/OfferManager.kt

@@ -81,10 +81,6 @@ class OfferManager(val nodeParams: NodeParams, val walletParams: WalletParams, v
         return OnionMessages.decryptMessage(nodeParams.nodePrivateKey, msg, logger)?.let { decrypted ->
             val invoiceRequestTlvs = decrypted.content.records.get<OnionMessagePayloadTlv.InvoiceRequest>()?.tlvs
             when {
-                decrypted.useCompactRoute -> {
-                    logger.warning { "unhandled compact route" }
-                    null
-                }
                 invoiceRequestTlvs != null -> when (val invoiceRequest = OfferTypes.InvoiceRequest.validate(invoiceRequestTlvs)) {
                     is Left -> {
                         logger.warning { "received invalid invoice_request: ${invoiceRequest.value}" }
@@ -240,6 +236,9 @@ class OfferManager(val nodeParams: NodeParams, val walletParams: WalletParams, v
     /** This function verifies that the offer provided was generated by us. */
     private fun isOurOffer(offer: OfferTypes.Offer, pathId: ByteVector?, blindedPrivateKey: PrivateKey): Boolean = when {
         pathId != null && pathId.size() != 32 -> false
+        // Compact offers are randomly generated, but they don't store the nonce in the path_id to save space.
+        // It is instead the wallet's responsibility to store the corresponding blinded public key(s).
+        pathId == null && nodeParams.compactOfferKeys.value.contains(blindedPrivateKey.publicKey()) -> offer.isMinimal()
         else -> {
             val expected = deterministicOffer(nodeParams.chainHash, nodeParams.nodePrivateKey, walletParams.trampolineNode.id, offer.amount, offer.description, pathId?.let { ByteVector32(it) })
             expected == OfferTypes.OfferAndKey(offer, blindedPrivateKey)

modules/core/src/commonMain/kotlin/fr/acinq/lightning/wire/OfferTypes.kt

@@ -758,6 +758,8 @@ object OfferTypes {
 
         val offerId: ByteVector32 = rootHash(records)
 
+        fun isMinimal(): Boolean = records.records.filterNot { it is OfferChains || it is OfferPaths || it is OfferIssuerId}.isEmpty() && records.unknown.isEmpty()
+
         companion object {
             val hrp = "lno"