Witness-only option for fundrawtransaction

Github-Pull: #25183
Rebased-From: 1c5cfd84b3dc14ab886acd47c7891c11eb2457ec

src/rpc/client.cpp

@@ -138,6 +138,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "fundrawtransaction", 1, "lockUnspents"},
     { "fundrawtransaction", 1, "fee_rate"},
     { "fundrawtransaction", 1, "feeRate"},
+    { "fundrawtransaction", 1, "segwit_inputs_only"},
     { "fundrawtransaction", 1, "subtractFeeFromOutputs"},
     { "fundrawtransaction", 1, "input_weights"},
     { "fundrawtransaction", 1, "conf_target"},

src/wallet/coincontrol.h

@@ -34,6 +34,8 @@ public:
     std::optional<OutputType> m_change_type;
     //! If false, only safe inputs will be used
     bool m_include_unsafe_inputs = false;
+    //! If true, only segwit inputs are selected
+    bool m_segwit_inputs_only = false;
     //! If true, the selection process can add extra unselected inputs from the wallet
     //! while requires all selected inputs be used
     bool m_allow_other_inputs = true;

src/wallet/rpc/spend.cpp

@@ -534,6 +534,7 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
                 {"minconf", UniValueType(UniValue::VNUM)},
                 {"maxconf", UniValueType(UniValue::VNUM)},
                 {"input_weights", UniValueType(UniValue::VARR)},
+                {"segwit_inputs_only", UniValueType(UniValue::VBOOL)},
             },
             true, true);
 
@@ -541,6 +542,10 @@ void FundTransaction(CWallet& wallet, CMutableTransaction& tx, CAmount& fee_out,
             coinControl.m_allow_other_inputs = options["add_inputs"].get_bool();
         }
 
+        if (options.exists("segwit_inputs_only")) {
+            coinControl.m_segwit_inputs_only = options["segwit_inputs_only"].get_bool();
+        }
+
         if (options.exists("changeAddress") || options.exists("change_address")) {
             const std::string change_address_str = (options.exists("change_address") ? options["change_address"] : options["changeAddress"]).get_str();
             CTxDestination dest = DecodeDestination(change_address_str);
@@ -799,6 +804,7 @@ RPCHelpMan fundrawtransaction()
                                     },
                                 },
                              },
+                            {"segwit_inputs_only", RPCArg::Type::BOOL, RPCArg::Default{false}, "Whether to only use segwit inputs for transaction."},
                         },
                         FundTxDoc()),
                         RPCArgOptions{

src/wallet/spend.cpp

@@ -408,6 +408,10 @@ CoinsResult AvailableCoins(const CWallet& wallet,
 
             std::unique_ptr<SigningProvider> provider = wallet.GetSolvingProvider(output.scriptPubKey);
 
+            if (coinControl && coinControl->m_segwit_inputs_only && !IsSegWitOutput(*provider, wtx.tx->vout[i].scriptPubKey)) {
+                continue;
+            }
+
             int input_bytes = CalculateMaximumSignedInputSize(output, COutPoint(), provider.get(), can_grind_r, coinControl);
             // Because CalculateMaximumSignedInputSize infers a solvable descriptor to get the satisfaction size,
             // it is safe to assume that this input is solvable if input_bytes is greater than -1.

test/functional/wallet_fundrawtransaction.py

@@ -136,6 +136,7 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.test_locked_wallet()
         self.test_many_inputs_fee()
         self.test_many_inputs_send()
+        self.test_witness_only()
         self.test_op_return()
         self.test_watchonly()
         self.test_all_watched_funds()
@@ -188,6 +189,38 @@ class RawTransactionsTest(BitcoinTestFramework):
         dec_tx  = self.nodes[2].decoderawtransaction(rawtxfund['hex'])
         assert len(dec_tx['vin']) > 0  #test that we have enough inputs
 
+    def check_witness_inputs(self, vins):
+        for vin in vins:
+            # check vin is a segwit input
+            utxo = self.nodes[2].gettxout(vin['txid'], vin['vout'])
+            info = self.nodes[2].getaddressinfo(utxo['scriptPubKey']['address'])
+            if not info['iswitness']:
+                return False
+
+        return True
+
+    def test_witness_only(self):
+        self.log.info("Testing fundrawtxn with witness inputs only")
+
+        inputs  = [ ]
+
+        # make sure legacy inputs are not accepted in witness only mode if no witness inputs are found
+        self.generatetoaddress(self.nodes[2], 2, self.nodes[2].getnewaddress(address_type='legacy'))
+        outputs = { self.nodes[2].getnewaddress() : 10.0 }
+        rawtx   = self.nodes[2].createrawtransaction(inputs, outputs)
+        assert_raises_rpc_error(-4, "Insufficient funds", self.nodes[2].fundrawtransaction, rawtx, {'segwit_inputs_only': True })
+
+        # make sure all inputs are of type witness
+        outputs = { self.nodes[2].getnewaddress() : 300.0 } # will generate many inputs
+        rawtx   = self.nodes[2].createrawtransaction(inputs, outputs)
+        self.generatetoaddress(self.nodes[2], 150, self.nodes[2].getnewaddress(address_type='bech32'))
+        rawtxfund = self.nodes[2].fundrawtransaction(rawtx, {'segwit_inputs_only': True })
+        dec_tx = self.nodes[2].decoderawtransaction(rawtxfund['hex'])
+
+        assert len(dec_tx['vin']) > 0
+        assert(self.check_witness_inputs(dec_tx['vin']))
+
+
     def test_simple_two_coins(self):
         self.log.info("Test fundrawtxn with 2 coins")
         inputs  = [ ]