1 files changed, 30 insertions, 21 deletions

diff --git a/src/script/sign.cpp b/src/script/sign.cpp
index 89cc7c808c..2795dc96d3 100644
--- a/src/script/sign.cpp
+++ b/src/script/sign.cpp
@@ -123,7 +123,7 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
     case TX_PUBKEYHASH: {
         CKeyID keyID = CKeyID(uint160(vSolutions[0]));
         CPubKey pubkey;
-        GetPubKey(provider, sigdata, keyID, pubkey);
+        if (!GetPubKey(provider, sigdata, keyID, pubkey)) return false;
         if (!CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) return false;
         ret.push_back(std::move(sig));
         ret.push_back(ToByteVector(pubkey));
@@ -239,10 +239,17 @@ bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreato
     return sigdata.complete;
 }
 
-bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, int index, int sighash)
+bool PSBTInputSigned(PSBTInput& input)
 {
-    // if this input has a final scriptsig or scriptwitness, don't do anything with it
-    if (!input.final_script_sig.empty() || !input.final_script_witness.IsNull()) {
+    return !input.final_script_sig.empty() || !input.final_script_witness.IsNull();
+}
+
+bool SignPSBTInput(const SigningProvider& provider, PartiallySignedTransaction& psbt, int index, int sighash)
+{
+    PSBTInput& input = psbt.inputs.at(index);
+    const CMutableTransaction& tx = *psbt.tx;
+
+    if (PSBTInputSigned(input)) {
         return true;
     }
 
@@ -253,15 +260,19 @@ bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& t
     // Get UTXO
     bool require_witness_sig = false;
     CTxOut utxo;
+
+    // Verify input sanity, which checks that at most one of witness or non-witness utxos is provided.
+    if (!input.IsSane()) {
+        return false;
+    }
+
     if (input.non_witness_utxo) {
         // If we're taking our information from a non-witness UTXO, verify that it matches the prevout.
-        if (input.non_witness_utxo->GetHash() != tx.vin[index].prevout.hash) return false;
-        // If both witness and non-witness UTXO are provided, verify that they match. This check shouldn't
-        // matter, as the PSBT deserializer enforces only one of both is provided, and the only way both
-        // can be present is when they're added simultaneously by FillPSBT (in which case they always match).
-        // Still, check in order to not rely on callers to enforce this.
-        if (!input.witness_utxo.IsNull() && input.non_witness_utxo->vout[tx.vin[index].prevout.n] != input.witness_utxo) return false;
-        utxo = input.non_witness_utxo->vout[tx.vin[index].prevout.n];
+        COutPoint prevout = tx.vin[index].prevout;
+        if (input.non_witness_utxo->GetHash() != prevout.hash) {
+            return false;
+        }
+        utxo = input.non_witness_utxo->vout[prevout.n];
     } else if (!input.witness_utxo.IsNull()) {
         utxo = input.witness_utxo;
         // When we're taking our information from a witness UTXO, we can't verify it is actually data from
@@ -280,18 +291,10 @@ bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& t
     if (require_witness_sig && !sigdata.witness) return false;
     input.FromSignatureData(sigdata);
 
+    // If we have a witness signature, use the smaller witness UTXO.
     if (sigdata.witness) {
-        assert(!utxo.IsNull());
         input.witness_utxo = utxo;
-    }
-
-    // If both UTXO types are present, drop the unnecessary one.
-    if (input.non_witness_utxo && !input.witness_utxo.IsNull()) {
-        if (sigdata.witness) {
-            input.non_witness_utxo = nullptr;
-        } else {
-            input.witness_utxo.SetNull();
-        }
+        input.non_witness_utxo = nullptr;
     }
 
     return sig_complete;
@@ -513,6 +516,12 @@ bool IsSolvable(const SigningProvider& provider, const CScript& script)
     return false;
 }
 
+PartiallySignedTransaction::PartiallySignedTransaction(const CTransaction& tx) : tx(tx)
+{
+    inputs.resize(tx.vin.size());
+    outputs.resize(tx.vout.size());
+}
+
 bool PartiallySignedTransaction::IsNull() const
 {
     return !tx && inputs.empty() && outputs.empty() && unknown.empty();