From c3981e379fa088aa7aa03b2f505342a5b3bc3436 Mon Sep 17 00:00:00 2001
From: S3RK <1466284+S3RK@users.noreply.github.com>
Date: Wed, 18 May 2022 08:25:04 +0200
Subject: [PATCH 1/2] wallet: do not count wallet utxos as external

---
 src/wallet/rpc/spend.cpp | 13 -------------
 src/wallet/spend.cpp     | 22 ++++++++++++++++++----
 2 files changed, 18 insertions(+), 17 deletions(-)

diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp
index 3d975b54024..9020eade237 100644
--- a/src/wallet/rpc/spend.cpp
+++ b/src/wallet/rpc/spend.cpp
@@ -699,19 +699,6 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
         setSubtractFeeFromOutputs.insert(pos);
     }
 
-    // Fetch specified UTXOs from the UTXO set to get the scriptPubKeys and values of the outputs being selected
-    // and to match with the given solving_data. Only used for non-wallet outputs.
-    std::map<COutPoint, Coin> coins;
-    for (const CTxIn& txin : tx.vin) {
-        coins[txin.prevout]; // Create empty map entry keyed by prevout.
-    }
-    wallet.chain().findCoins(coins);
-    for (const auto& coin : coins) {
-        if (!coin.second.out.IsNull()) {
-            coinControl.SelectExternal(coin.first, coin.second.out);
-        }
-    }
-
     bilingual_str error;
 
     if (!FundTransaction(wallet, tx, fee_out, change_position, error, lockUnspents, setSubtractFeeFromOutputs, coinControl)) {
diff --git a/src/wallet/spend.cpp b/src/wallet/spend.cpp
index e5fd7b0eb4a..162d06e596b 100644
--- a/src/wallet/spend.cpp
+++ b/src/wallet/spend.cpp
@@ -1018,14 +1018,28 @@ bool FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& nFeeRet,
 
     coinControl.fAllowOtherInputs = true;
 
-    for (const CTxIn& txin : tx.vin) {
-        coinControl.Select(txin.prevout);
-    }
-
     // Acquire the locks to prevent races to the new locked unspents between the
     // CreateTransaction call and LockCoin calls (when lockUnspents is true).
     LOCK(wallet.cs_wallet);
 
+    // Fetch specified UTXOs from the UTXO set to get the scriptPubKeys and values of the outputs being selected
+    // and to match with the given solving_data. Only used for non-wallet outputs.
+    std::map<COutPoint, Coin> coins;
+    for (const CTxIn& txin : tx.vin) {
+        coins[txin.prevout]; // Create empty map entry keyed by prevout.
+    }
+    wallet.chain().findCoins(coins);
+
+    for (const CTxIn& txin : tx.vin) {
+        // if it's not in the wallet and corresponding UTXO is found than select as external output
+        const auto& outPoint = txin.prevout;
+        if (wallet.mapWallet.find(outPoint.hash) == wallet.mapWallet.end() && !coins[outPoint].out.IsNull()) {
+            coinControl.SelectExternal(outPoint, coins[outPoint].out);
+        } else {
+            coinControl.Select(outPoint);
+        }
+    }
+
     FeeCalculation fee_calc_out;
     std::optional<CreatedTransactionResult> txr = CreateTransaction(wallet, vecSend, nChangePosInOut, error, coinControl, fee_calc_out, false);
     if (!txr) return false;

From 7832e9438f5c66b88f60676d14e1e11d669eb109 Mon Sep 17 00:00:00 2001
From: S3RK <1466284+S3RK@users.noreply.github.com>
Date: Wed, 30 Mar 2022 09:18:33 +0200
Subject: [PATCH 2/2] test: fundrawtransaction preset input weight calculation

---
 test/functional/rpc_fundrawtransaction.py | 25 +++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/test/functional/rpc_fundrawtransaction.py b/test/functional/rpc_fundrawtransaction.py
index 759e43194bd..948deaaec44 100755
--- a/test/functional/rpc_fundrawtransaction.py
+++ b/test/functional/rpc_fundrawtransaction.py
@@ -11,6 +11,9 @@ from math import ceil
 
 from test_framework.descriptors import descsum_create
 from test_framework.key import ECKey
+from test_framework.messages import (
+    COIN,
+)
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_approx,
@@ -103,6 +106,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.generate(self.nodes[2], 1)
         self.generate(self.nodes[0], 121)
 
+        self.test_weight_calculation()
         self.test_change_position()
         self.test_simple()
         self.test_simple_two_coins()
@@ -1069,6 +1073,27 @@ class RawTransactionsTest(BitcoinTestFramework):
 
         self.nodes[2].unloadwallet("extfund")
 
+    def test_weight_calculation(self):
+        self.log.info("Test weight calculation with external inputs")
+
+        self.nodes[2].createwallet("test_weight_calculation")
+        wallet = self.nodes[2].get_wallet_rpc("test_weight_calculation")
+
+        addr = wallet.getnewaddress()
+        txid = self.nodes[0].sendtoaddress(addr, 5)
+        vout = find_vout_for_address(self.nodes[0], txid, addr)
+
+        self.nodes[0].sendtoaddress(wallet.getnewaddress(), 5)
+        self.generate(self.nodes[0], 1)
+
+        rawtx = wallet.createrawtransaction([{'txid': txid, 'vout': vout}], [{self.nodes[0].getnewaddress(): 9.999}])
+        fundedtx = wallet.fundrawtransaction(rawtx, {'fee_rate': 10})
+        # with 71-byte signatures we should expect following tx size
+        tx_size = 10 + 41*2 + 31*2 + (2 + 107*2)/4
+        assert_equal(fundedtx['fee'] * COIN, tx_size * 10)
+
+        self.nodes[2].unloadwallet("test_weight_calculation")
+
     def test_include_unsafe(self):
         self.log.info("Test fundrawtxn with unsafe inputs")