From 4d335bb1e00a414a4740007d5a192a73179b2262 Mon Sep 17 00:00:00 2001
From: Andrew Chow <achow101-github@achow101.com>
Date: Tue, 31 May 2022 23:51:49 -0400
Subject: wallet: Set preset input sequence through coin control

---
 src/wallet/coincontrol.cpp | 16 ++++++++++++++++
 src/wallet/coincontrol.h   |  9 +++++++++
 src/wallet/spend.cpp       | 15 ++++++++++++---
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/wallet/coincontrol.cpp b/src/wallet/coincontrol.cpp
index 00852b5f85..f13b7073be 100644
--- a/src/wallet/coincontrol.cpp
+++ b/src/wallet/coincontrol.cpp
@@ -72,6 +72,12 @@ std::optional<int64_t> CCoinControl::GetInputWeight(const COutPoint& outpoint) c
     return it != m_selected.end() ? it->second.GetInputWeight() : std::nullopt;
 }
 
+std::optional<uint32_t> CCoinControl::GetSequence(const COutPoint& outpoint) const
+{
+    const auto it = m_selected.find(outpoint);
+    return it != m_selected.end() ? it->second.GetSequence() : std::nullopt;
+}
+
 void PreselectedInput::SetTxOut(const CTxOut& txout)
 {
     m_txout = txout;
@@ -97,4 +103,14 @@ std::optional<int64_t> PreselectedInput::GetInputWeight() const
 {
     return m_weight;
 }
+
+void PreselectedInput::SetSequence(uint32_t sequence)
+{
+    m_sequence = sequence;
+}
+
+std::optional<uint32_t> PreselectedInput::GetSequence() const
+{
+    return m_sequence;
+}
 } // namespace wallet
diff --git a/src/wallet/coincontrol.h b/src/wallet/coincontrol.h
index e7a16e37df..32595955f0 100644
--- a/src/wallet/coincontrol.h
+++ b/src/wallet/coincontrol.h
@@ -31,6 +31,8 @@ private:
     std::optional<CTxOut> m_txout;
     //! The input weight for spending this input
     std::optional<int64_t> m_weight;
+    //! The sequence number for this input
+    std::optional<uint32_t> m_sequence;
 
 public:
     /**
@@ -47,6 +49,11 @@ public:
     void SetInputWeight(int64_t weight);
     /** Retrieve the input weight for this input. */
     std::optional<int64_t> GetInputWeight() const;
+
+    /** Set the sequence for this input. */
+    void SetSequence(uint32_t sequence);
+    /** Retrieve the sequence for this input. */
+    std::optional<uint32_t> GetSequence() const;
 };
 
 /** Coin Control Features. */
@@ -128,6 +135,8 @@ public:
      * Returns the input weight.
      */
     std::optional<int64_t> GetInputWeight(const COutPoint& outpoint) const;
+    /** Retrieve the sequence for an input */
+    std::optional<uint32_t> GetSequence(const COutPoint& outpoint) const;
 
 private:
     //! Selected inputs (inputs that will be used, regardless of whether they're optimal or not)
diff --git a/src/wallet/spend.cpp b/src/wallet/spend.cpp
index c3fd695eb9..7ec2775fb1 100644
--- a/src/wallet/spend.cpp
+++ b/src/wallet/spend.cpp
@@ -1150,11 +1150,19 @@ static util::Result<CreatedTransactionResult> CreateTransactionInternal(
     // to avoid conflicting with other possible uses of nSequence,
     // and in the spirit of "smallest possible change from prior
     // behavior."
-    const uint32_t nSequence{coin_control.m_signal_bip125_rbf.value_or(wallet.m_signal_rbf) ? MAX_BIP125_RBF_SEQUENCE : CTxIn::MAX_SEQUENCE_NONFINAL};
+    bool use_anti_fee_sniping = true;
+    const uint32_t default_sequence{coin_control.m_signal_bip125_rbf.value_or(wallet.m_signal_rbf) ? MAX_BIP125_RBF_SEQUENCE : CTxIn::MAX_SEQUENCE_NONFINAL};
     for (const auto& coin : selected_coins) {
-        txNew.vin.emplace_back(coin->outpoint, CScript(), nSequence);
+        std::optional<uint32_t> sequence = coin_control.GetSequence(coin->outpoint);
+        if (sequence) {
+            // If an input has a preset sequence, we can't do anti-fee-sniping
+            use_anti_fee_sniping = false;
+        }
+        txNew.vin.emplace_back(coin->outpoint, CScript(), sequence.value_or(default_sequence));
+    }
+    if (use_anti_fee_sniping) {
+        DiscourageFeeSniping(txNew, rng_fast, wallet.chain(), wallet.GetLastBlockHash(), wallet.GetLastBlockHeight());
     }
-    DiscourageFeeSniping(txNew, rng_fast, wallet.chain(), wallet.GetLastBlockHash(), wallet.GetLastBlockHeight());
 
     // Calculate the transaction fee
     TxSize tx_sizes = CalculateMaximumSignedTxSize(CTransaction(txNew), &wallet, &coin_control);
@@ -1357,6 +1365,7 @@ bool FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& nFeeRet,
             // The input was not in the wallet, but is in the UTXO set, so select as external
             preset_txin.SetTxOut(coins[outPoint].out);
         }
+        preset_txin.SetSequence(txin.nSequence);
     }
 
     auto res = CreateTransaction(wallet, vecSend, nChangePosInOut, coinControl, false);
-- 
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