From 4768ba608eeb6c9a3501353981a512d40242862d Mon Sep 17 00:00:00 2001
From: Pierre-Marie Padiou <pm47@users.noreply.github.com>
Date: Mon, 8 Jan 2024 13:45:11 +0100
Subject: [PATCH] Filter out txs that are too big for swap-in (#580)

There is a 65000 bytes limit for transactions, because they must fit in
Lightning messages during interactive-tx negotiation.
---
 .../fr/acinq/lightning/blockchain/electrum/SwapInManager.kt   | 4 +++-
 .../kotlin/fr/acinq/lightning/channel/InteractiveTx.kt        | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/commonMain/kotlin/fr/acinq/lightning/blockchain/electrum/SwapInManager.kt b/src/commonMain/kotlin/fr/acinq/lightning/blockchain/electrum/SwapInManager.kt
index 2c652d922..3cfc32aab 100644
--- a/src/commonMain/kotlin/fr/acinq/lightning/blockchain/electrum/SwapInManager.kt
+++ b/src/commonMain/kotlin/fr/acinq/lightning/blockchain/electrum/SwapInManager.kt
@@ -1,9 +1,11 @@
 package fr.acinq.lightning.blockchain.electrum
 
 import fr.acinq.bitcoin.OutPoint
+import fr.acinq.bitcoin.Transaction
 import fr.acinq.bitcoin.TxId
 import fr.acinq.lightning.Lightning
 import fr.acinq.lightning.SwapInParams
+import fr.acinq.lightning.channel.FundingContributions.Companion.stripInputWitnesses
 import fr.acinq.lightning.channel.LocalFundingStatus
 import fr.acinq.lightning.channel.RbfStatus
 import fr.acinq.lightning.channel.SignedSharedTransaction
@@ -38,7 +40,7 @@ class SwapInManager(private var reservedUtxos: Set<OutPoint>, private val logger
             val utxos = buildSet {
                 // some utxos may be used for swap-in even if they are not confirmed, for example when migrating from the legacy phoenix android app
                 addAll(availableWallet.all.filter { cmd.trustedTxs.contains(it.outPoint.txid) })
-                addAll(availableWallet.deeplyConfirmed)
+                addAll(availableWallet.deeplyConfirmed.filter { Transaction.write(it.previousTx.stripInputWitnesses()).size < 65_000 })
             }.toList()
             if (utxos.balance > 0.sat) {
                 logger.info { "swap-in wallet: requesting channel using ${utxos.size} utxos with balance=${utxos.balance}" }
diff --git a/src/commonMain/kotlin/fr/acinq/lightning/channel/InteractiveTx.kt b/src/commonMain/kotlin/fr/acinq/lightning/channel/InteractiveTx.kt
index 301f4aa7f..22c1aedca 100644
--- a/src/commonMain/kotlin/fr/acinq/lightning/channel/InteractiveTx.kt
+++ b/src/commonMain/kotlin/fr/acinq/lightning/channel/InteractiveTx.kt
@@ -255,7 +255,7 @@ data class FundingContributions(val inputs: List<InteractiveTxInput.Outgoing>, v
         }
 
         /** Strip input witnesses to save space (there is a max size on txs due to lightning message limits). */
-        private fun Transaction.stripInputWitnesses(): Transaction = copy(txIn = txIn.map { it.updateWitness(ScriptWitness.empty) })
+        fun Transaction.stripInputWitnesses(): Transaction = copy(txIn = txIn.map { it.updateWitness(ScriptWitness.empty) })
 
         /** Compute the weight we need to pay on-chain fees for. */
         private fun computeWeightPaid(isInitiator: Boolean, sharedInput: SharedFundingInput?, sharedOutputScript: ByteVector, walletInputs: List<WalletState.Utxo>, localOutputs: List<TxOut>): Int {