1 files changed, 12 insertions, 11 deletions
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 6885499be2..2900fb7f93 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -1448,19 +1448,13 @@ bool CWallet::AddWalletFlags(uint64_t flags)
 
 // Helper for producing a max-sized low-S low-R signature (eg 71 bytes)
 // or a max-sized low-S signature (e.g. 72 bytes) if use_max_sig is true
-bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout, bool use_max_sig) const
+bool DummySignInput(const SigningProvider& provider, CTxIn &tx_in, const CTxOut &txout, bool use_max_sig)
 {
     // Fill in dummy signatures for fee calculation.
     const CScript& scriptPubKey = txout.scriptPubKey;
     SignatureData sigdata;
 
-    std::unique_ptr<SigningProvider> provider = GetSolvingProvider(scriptPubKey);
-    if (!provider) {
-        // We don't know about this scriptpbuKey;
-        return false;
-    }
-
-    if (!ProduceSignature(*provider, use_max_sig ? DUMMY_MAXIMUM_SIGNATURE_CREATOR : DUMMY_SIGNATURE_CREATOR, scriptPubKey, sigdata)) {
+    if (!ProduceSignature(provider, use_max_sig ? DUMMY_MAXIMUM_SIGNATURE_CREATOR : DUMMY_SIGNATURE_CREATOR, scriptPubKey, sigdata)) {
         return false;
     }
     UpdateInput(tx_in, sigdata);
@@ -1468,14 +1462,21 @@ bool CWallet::DummySignInput(CTxIn &tx_in, const CTxOut &txout, bool use_max_sig
 }
 
 // Helper for producing a bunch of max-sized low-S low-R signatures (eg 71 bytes)
-bool CWallet::DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts, bool use_max_sig) const
+bool CWallet::DummySignTx(CMutableTransaction &txNew, const std::vector<CTxOut> &txouts, const CCoinControl* coin_control) const
 {
     // Fill in dummy signatures for fee calculation.
     int nIn = 0;
     for (const auto& txout : txouts)
     {
-        if (!DummySignInput(txNew.vin[nIn], txout, use_max_sig)) {
-            return false;
+        CTxIn& txin = txNew.vin[nIn];
+        // Use max sig if watch only inputs were used or if this particular input is an external input
+        // to ensure a sufficient fee is attained for the requested feerate.
+        const bool use_max_sig = coin_control && (coin_control->fAllowWatchOnly || coin_control->IsExternalSelected(txin.prevout));
+        const std::unique_ptr<SigningProvider> provider = GetSolvingProvider(txout.scriptPubKey);
+        if (!provider || !DummySignInput(*provider, txin, txout, use_max_sig)) {
+            if (!coin_control || !DummySignInput(coin_control->m_external_provider, txin, txout, use_max_sig)) {
+                return false;
+            }
         }
 
         nIn++;