partial bitcoin#13932: Additional utility RPCs for PSBT

Author: kwvg

src/script/sign.cpp

@@ -84,6 +84,8 @@ static bool CreateSig(const BaseSignatureCreator& creator, SignatureData& sigdat
         assert(i.second);
         return true;
     }
+    // Could not make signature or signature not found, add keyid to missing
+    sigdata.missing_sigs.push_back(keyid);
     return false;
 }
 
@@ -120,17 +122,24 @@ static bool SignStep(const SigningProvider& provider, const BaseSignatureCreator
     case TX_PUBKEYHASH: {
         CKeyID keyID = CKeyID(uint160(vSolutions[0]));
         CPubKey pubkey;
-        if (!GetPubKey(provider, sigdata, keyID, pubkey)) return false;
+        if (!GetPubKey(provider, sigdata, keyID, pubkey)) {
+            // Pubkey could not be found, add to missing
+            sigdata.missing_pubkeys.push_back(keyID);
+            return false;
+        }
         if (!CreateSig(creator, sigdata, provider, sig, pubkey, scriptPubKey, sigversion)) return false;
         ret.push_back(std::move(sig));
         ret.push_back(ToByteVector(pubkey));
         return true;
     }
     case TX_SCRIPTHASH:
-        if (GetCScript(provider, sigdata, uint160(vSolutions[0]), scriptRet)) {
+        h160 = uint160(vSolutions[0]);
+        if (GetCScript(provider, sigdata, h160, scriptRet)) {
             ret.push_back(std::vector<unsigned char>(scriptRet.begin(), scriptRet.end()));
             return true;
         }
+        // Could not find redeemScript, add to missing
+        sigdata.missing_redeem_script = h160;
         return false;
 
     case TX_MULTISIG: {
@@ -453,6 +462,37 @@ bool PartiallySignedTransaction::IsSane() const
     return true;
 }
 
+bool PartiallySignedTransaction::AddInput(const CTxIn& txin, PSBTInput& psbtin)
+{
+    if (std::find(tx->vin.begin(), tx->vin.end(), txin) != tx->vin.end()) {
+        return false;
+    }
+    tx->vin.push_back(txin);
+    psbtin.partial_sigs.clear();
+    psbtin.final_script_sig.clear();
+    inputs.push_back(psbtin);
+    return true;
+}
+
+bool PartiallySignedTransaction::AddOutput(const CTxOut& txout, const PSBTOutput& psbtout)
+{
+    tx->vout.push_back(txout);
+    outputs.push_back(psbtout);
+    return true;
+}
+
+bool PartiallySignedTransaction::GetInputUTXO(CTxOut& utxo, int input_index) const
+{
+    PSBTInput input = inputs[input_index];
+    int prevout_index = tx->vin[input_index].prevout.n;
+    if (input.non_witness_utxo) {
+        utxo = input.non_witness_utxo->vout[prevout_index];
+    } else {
+        return false;
+    }
+    return true;
+}
+
 bool PSBTInput::IsNull() const
 {
     return !non_witness_utxo && partial_sigs.empty() && unknown.empty() && hd_keypaths.empty() && redeem_script.empty();

src/script/sign.h

@@ -108,6 +108,9 @@ struct SignatureData {
     CScript redeem_script; ///< The redeemScript (if any) for the input
     std::map<CKeyID, SigPair> signatures; ///< BIP 174 style partial signatures for the input. May contain all signatures necessary for producing a final scriptSig.
     std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>> misc_pubkeys;
+    std::vector<CKeyID> missing_pubkeys; ///< KeyIDs of pubkeys which could not be found
+    std::vector<CKeyID> missing_sigs; ///< KeyIDs of pubkeys for signatures which could not be found
+    uint160 missing_redeem_script; ///< ScriptID of the missing redeemScript (if any)
 
     SignatureData() {}
     explicit SignatureData(const CScript& script) : scriptSig(script) {}
@@ -474,6 +477,8 @@ struct PartiallySignedTransaction
     bool IsNull() const;
     void Merge(const PartiallySignedTransaction& psbt);
     bool IsSane() const;
+    bool AddInput(const CTxIn& txin, PSBTInput& psbtin);
+    bool AddOutput(const CTxOut& txout, const PSBTOutput& psbtout);
     PartiallySignedTransaction() {}
     PartiallySignedTransaction(const PartiallySignedTransaction& psbt_in) : tx(psbt_in.tx), inputs(psbt_in.inputs), outputs(psbt_in.outputs), unknown(psbt_in.unknown) {}
 
@@ -487,6 +492,15 @@ struct PartiallySignedTransaction
         return !(a == b);
     }
 
+    /**
+     * Finds the UTXO for a given input index
+     *
+     * @param[out] utxo The UTXO of the input if found
+     * @param[in] input_index Index of the input to retrieve the UTXO of
+     * @return Whether the UTXO for the specified input was found
+     */
+    bool GetInputUTXO(CTxOut& utxo, int input_index) const;
+
     template <typename Stream>
     inline void Serialize(Stream& s) const {