Create wallet RPCs for PSBT

walletprocesspsbt takes a PSBT format transaction, updates the
PSBT with any inputs related to this wallet, signs, and finalizes
the transaction. There is also an option to not sign and just
update.

walletcreatefundedpsbt creates a PSBT from user provided data
in the same form as createrawtransaction. It also funds the transaction
and takes an options argument in the same form as fundrawtransaction.
The resulting PSBT is blank with no input or output data filled
in.

Author: achow101

src/core_io.h

@@ -26,6 +26,7 @@ bool DecodeHexBlk(CBlock&, const std::string& strHexBlk);
 uint256 ParseHashStr(const std::string&, const std::string& strName);
 std::vector<unsigned char> ParseHexUV(const UniValue& v, const std::string& strName);
 bool DecodePSBT(PartiallySignedTransaction& psbt, const std::string& base64_tx, std::string& error);
+int ParseSighashString(const UniValue& sighash);
 
 // core_write.cpp
 UniValue ValueFromAmount(const CAmount& amount);

src/core_read.cpp

@@ -197,3 +197,26 @@ std::vector<unsigned char> ParseHexUV(const UniValue& v, const std::string& strN
         throw std::runtime_error(strName + " must be hexadecimal string (not '" + strHex + "')");
     return ParseHex(strHex);
 }
+
+int ParseSighashString(const UniValue& sighash)
+{
+    int hash_type = SIGHASH_ALL;
+    if (!sighash.isNull()) {
+        static std::map<std::string, int> map_sighash_values = {
+            {std::string("ALL"), int(SIGHASH_ALL)},
+            {std::string("ALL|ANYONECANPAY"), int(SIGHASH_ALL|SIGHASH_ANYONECANPAY)},
+            {std::string("NONE"), int(SIGHASH_NONE)},
+            {std::string("NONE|ANYONECANPAY"), int(SIGHASH_NONE|SIGHASH_ANYONECANPAY)},
+            {std::string("SINGLE"), int(SIGHASH_SINGLE)},
+            {std::string("SINGLE|ANYONECANPAY"), int(SIGHASH_SINGLE|SIGHASH_ANYONECANPAY)},
+        };
+        std::string strHashType = sighash.get_str();
+        const auto& it = map_sighash_values.find(strHashType);
+        if (it != map_sighash_values.end()) {
+            hash_type = it->second;
+        } else {
+            throw std::runtime_error(strHashType + " is not a valid sighash parameter.");
+        }
+    }
+    return hash_type;
+}

src/rpc/client.cpp

@@ -109,6 +109,14 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "combinerawtransaction", 0, "txs" },
     { "fundrawtransaction", 1, "options" },
     { "fundrawtransaction", 2, "iswitness" },
+    { "walletcreatefundedpsbt", 0, "inputs" },
+    { "walletcreatefundedpsbt", 1, "outputs" },
+    { "walletcreatefundedpsbt", 2, "locktime" },
+    { "walletcreatefundedpsbt", 3, "replaceable" },
+    { "walletcreatefundedpsbt", 4, "options" },
+    { "walletcreatefundedpsbt", 5, "bip32derivs" },
+    { "walletprocesspsbt", 1, "sign" },
+    { "walletprocesspsbt", 3, "bip32derivs" },
     { "createpsbt", 0, "inputs" },
     { "createpsbt", 1, "outputs" },
     { "createpsbt", 2, "locktime" },

src/rpc/rawtransaction.cpp

@@ -840,23 +840,7 @@ UniValue SignTransaction(CMutableTransaction& mtx, const UniValue& prevTxsUnival
         }
     }
 
-    int nHashType = SIGHASH_ALL;
-    if (!hashType.isNull()) {
-        static std::map<std::string, int> mapSigHashValues = {
-            {std::string("ALL"), int(SIGHASH_ALL)},
-            {std::string("ALL|ANYONECANPAY"), int(SIGHASH_ALL|SIGHASH_ANYONECANPAY)},
-            {std::string("NONE"), int(SIGHASH_NONE)},
-            {std::string("NONE|ANYONECANPAY"), int(SIGHASH_NONE|SIGHASH_ANYONECANPAY)},
-            {std::string("SINGLE"), int(SIGHASH_SINGLE)},
-            {std::string("SINGLE|ANYONECANPAY"), int(SIGHASH_SINGLE|SIGHASH_ANYONECANPAY)},
-        };
-        std::string strHashType = hashType.get_str();
-        if (mapSigHashValues.count(strHashType)) {
-            nHashType = mapSigHashValues[strHashType];
-        } else {
-            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid sighash param");
-        }
-    }
+    int nHashType = ParseSighashString(hashType);
 
     bool fHashSingle = ((nHashType & ~SIGHASH_ANYONECANPAY) == SIGHASH_SINGLE);
 

src/script/sign.cpp

@@ -614,3 +614,13 @@ void PSBTOutput::Merge(const PSBTOutput& output)
     if (redeem_script.empty() && !output.redeem_script.empty()) redeem_script = output.redeem_script;
     if (witness_script.empty() && !output.witness_script.empty()) witness_script = output.witness_script;
 }
+
+bool PublicOnlySigningProvider::GetCScript(const CScriptID &scriptid, CScript& script) const
+{
+    return m_provider->GetCScript(scriptid, script);
+}
+
+bool PublicOnlySigningProvider::GetPubKey(const CKeyID &address, CPubKey& pubkey) const
+{
+    return m_provider->GetPubKey(address, pubkey);
+}

src/script/sign.h

@@ -32,6 +32,17 @@ class SigningProvider
 
 extern const SigningProvider& DUMMY_SIGNING_PROVIDER;
 
+class PublicOnlySigningProvider : public SigningProvider
+{
+private:
+    const SigningProvider* m_provider;
+
+public:
+    PublicOnlySigningProvider(const SigningProvider* provider) : m_provider(provider) {}
+    bool GetCScript(const CScriptID &scriptid, CScript& script) const;
+    bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const;
+};
+
 /** Interface for signature creators. */
 class BaseSignatureCreator {
 public: