Merge #19501: send* RPCs in the wallet returns the "fee reason"

69cf5d4eeb73f7d685e915fc17af64634d88a4a2 [test] Make sure send rpc returns fee reason (Sishir Giri)
d5863c0b3e20d56acf7246008b7832efde68ab21 [send] Make send RPCs return fee reason (Sishir Giri)

Pull request description:

  Whenever a wallet funds a transaction, the fee reason is reported to the user only if the verbose is set to true. I added an extra parameter to `CreateTransaction` function in wallet.cpp. Then I implemented the fee reason return logic in `SendMoney`  in rpcwallet.cpp, followed by verbose parameter in `sendtoaddress` and `sendmany` functions. I also added a fee reason test case in walletbasic.py.

  link to the issue: https://github.com/MarcoFalke/bitcoin-core/issues/22#issue-616251578

ACKs for top commit:
  instagibbs:
    ACK https://github.com/bitcoin/bitcoin/pull/19501/commits/69cf5d4eeb73f7d685e915fc17af64634d88a4a2
  meshcollider:
    utACK 69cf5d4eeb73f7d685e915fc17af64634d88a4a2

Tree-SHA512: 2e3af32dcfbd5511ba95f8bc8edca7acfe709a8430ff03e43172e5d0af3dfa4b2f57906978e7f272d878043b9ed8c6004674cf47d7496b005d5f612e9a58aa0e

8 files changed, 71 insertions, 20 deletions

diff --git a/src/interfaces/wallet.cpp b/src/interfaces/wallet.cpp
index 94c63da84e..f68016b557 100644
--- a/src/interfaces/wallet.cpp
+++ b/src/interfaces/wallet.cpp
@@ -231,8 +231,9 @@ public:
     {
         LOCK(m_wallet->cs_wallet);
         CTransactionRef tx;
+        FeeCalculation fee_calc_out;
         if (!m_wallet->CreateTransaction(recipients, tx, fee, change_pos,
-                fail_reason, coin_control, sign)) {
+                fail_reason, coin_control, fee_calc_out, sign)) {
             return {};
         }
         return tx;
diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index 3c432464f2..88c8ebe1f6 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -41,6 +41,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "sendtoaddress", 5 , "replaceable" },
     { "sendtoaddress", 6 , "conf_target" },
     { "sendtoaddress", 8, "avoid_reuse" },
+    { "sendtoaddress", 9, "verbose"},
     { "settxfee", 0, "amount" },
     { "sethdseed", 0, "newkeypool" },
     { "getreceivedbyaddress", 1, "minconf" },
@@ -72,6 +73,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "sendmany", 4, "subtractfeefrom" },
     { "sendmany", 5 , "replaceable" },
     { "sendmany", 6 , "conf_target" },
+    { "sendmany", 8, "verbose" },
     { "deriveaddresses", 1, "range" },
     { "scantxoutset", 1, "scanobjects" },
     { "addmultisigaddress", 0, "nrequired" },
diff --git a/src/wallet/feebumper.cpp b/src/wallet/feebumper.cpp
index cacf306891..6cbad14de8 100644
--- a/src/wallet/feebumper.cpp
+++ b/src/wallet/feebumper.cpp
@@ -219,7 +219,8 @@ Result CreateRateBumpTransaction(CWallet& wallet, const uint256& txid, const CCo
     CAmount fee_ret;
     int change_pos_in_out = -1; // No requested location for change
     bilingual_str fail_reason;
-    if (!wallet.CreateTransaction(recipients, tx_new, fee_ret, change_pos_in_out, fail_reason, new_coin_control, false)) {
+    FeeCalculation fee_calc_out;
+    if (!wallet.CreateTransaction(recipients, tx_new, fee_ret, change_pos_in_out, fail_reason, new_coin_control, fee_calc_out, false)) {
         errors.push_back(Untranslated("Unable to create transaction.") + Untranslated(" ") + fail_reason);
         return Result::WALLET_ERROR;
     }
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index 70e99a308e..da50f6f215 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -397,7 +397,7 @@ void ParseRecipients(const UniValue& address_amounts, const UniValue& subtract_f
     }
 }
 
-UniValue SendMoney(CWallet* const pwallet, const CCoinControl &coin_control, std::vector<CRecipient> &recipients, mapValue_t map_value)
+UniValue SendMoney(CWallet* const pwallet, const CCoinControl &coin_control, std::vector<CRecipient> &recipients, mapValue_t map_value, bool verbose)
 {
     EnsureWalletIsUnlocked(pwallet);
 
@@ -409,11 +409,18 @@ UniValue SendMoney(CWallet* const pwallet, const CCoinControl &coin_control, std
     int nChangePosRet = -1;
     bilingual_str error;
     CTransactionRef tx;
-    bool fCreated = pwallet->CreateTransaction(recipients, tx, nFeeRequired, nChangePosRet, error, coin_control, !pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
+    FeeCalculation fee_calc_out;
+    bool fCreated = pwallet->CreateTransaction(recipients, tx, nFeeRequired, nChangePosRet, error, coin_control, fee_calc_out, !pwallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS));
     if (!fCreated) {
         throw JSONRPCError(RPC_WALLET_INSUFFICIENT_FUNDS, error.original);
     }
     pwallet->CommitTransaction(tx, std::move(map_value), {} /* orderForm */);
+    if (verbose) {
+        UniValue entry(UniValue::VOBJ);
+        entry.pushKV("txid", tx->GetHash().GetHex());
+        entry.pushKV("fee_reason", StringForFeeReason(fee_calc_out.reason));
+        return entry;
+    }
     return tx->GetHash().GetHex();
 }
 
@@ -438,9 +445,19 @@ static RPCHelpMan sendtoaddress()
             "       \"" + FeeModes("\"\n\"") + "\""},
                     {"avoid_reuse", RPCArg::Type::BOOL, /* default */ "true", "(only available if avoid_reuse wallet flag is set) Avoid spending from dirty addresses; addresses are considered\n"
             "                             dirty if they have previously been used in a transaction."},
+                    {"verbose", RPCArg::Type::BOOL, /* default */ "false", "If true, return extra information about the transaction."},
                 },
-                RPCResult{
-                    RPCResult::Type::STR_HEX, "txid", "The transaction id."
+                {
+                    RPCResult{"if verbose is not set or set to false",
+                        RPCResult::Type::STR_HEX, "txid", "The transaction id."
+                    },
+                    RPCResult{"if verbose is set to true",
+                        RPCResult::Type::OBJ, "", "",
+                        {
+                            {RPCResult::Type::STR_HEX, "txid", "The transaction id."},
+                            {RPCResult::Type::STR, "fee reason", "The transaction fee reason."}
+                        },
+                    },
                 },
                 RPCExamples{
                     HelpExampleCli("sendtoaddress", "\"" + EXAMPLE_ADDRESS[0] + "\" 0.1")
@@ -497,8 +514,9 @@ static RPCHelpMan sendtoaddress()
 
     std::vector<CRecipient> recipients;
     ParseRecipients(address_amounts, subtractFeeFromAmount, recipients);
+    bool verbose = request.params[9].isNull() ? false: request.params[9].get_bool();
 
-    return SendMoney(pwallet, coin_control, recipients, mapValue);
+    return SendMoney(pwallet, coin_control, recipients, mapValue, verbose);
 },
     };
 }
@@ -853,11 +871,22 @@ static RPCHelpMan sendmany()
                     {"conf_target", RPCArg::Type::NUM, /* default */ "wallet default", "Confirmation target (in blocks), or fee rate (for " + CURRENCY_UNIT + "/kB or " + CURRENCY_ATOM + "/B estimate modes)"},
                     {"estimate_mode", RPCArg::Type::STR, /* default */ "unset", std::string() + "The fee estimate mode, must be one of (case insensitive):\n"
             "       \"" + FeeModes("\"\n\"") + "\""},
+                    {"verbose", RPCArg::Type::BOOL, /* default */ "false", "If true, return extra infomration about the transaction."},
+                },
+                {
+                    RPCResult{"if verbose is not set or set to false",
+                        RPCResult::Type::STR_HEX, "txid", "The transaction id for the send. Only  1 transaction is created regardless of\n"
+                "the number of addresses."
+                    },
+                    RPCResult{"if verbose is set to true",
+                        RPCResult::Type::OBJ, "", "",
+                        {
+                            {RPCResult::Type::STR_HEX, "txid", "The transaction id for the send. Only 1 transaction is created regardless of\n"
+                "the number of addresses."},
+                            {RPCResult::Type::STR, "fee reason", "The transaction fee reason."}
+                        },
+                    },
                 },
-                 RPCResult{
-                     RPCResult::Type::STR_HEX, "txid", "The transaction id for the send. Only 1 transaction is created regardless of\n"
-            "the number of addresses."
-                 },
                 RPCExamples{
             "\nSend two amounts to two different addresses:\n"
             + HelpExampleCli("sendmany", "\"\" \"{\\\"" + EXAMPLE_ADDRESS[0] + "\\\":0.01,\\\"" + EXAMPLE_ADDRESS[1] + "\\\":0.02}\"") +
@@ -902,12 +931,14 @@ static RPCHelpMan sendmany()
 
     std::vector<CRecipient> recipients;
     ParseRecipients(sendTo, subtractFeeFromAmount, recipients);
+    bool verbose = request.params[8].isNull() ? false : request.params[8].get_bool();
 
-    return SendMoney(pwallet, coin_control, recipients, std::move(mapValue));
+    return SendMoney(pwallet, coin_control, recipients, std::move(mapValue), verbose);
 },
     };
 }
 
+
 static RPCHelpMan addmultisigaddress()
 {
     return RPCHelpMan{"addmultisigaddress",
@@ -4500,8 +4531,8 @@ static const CRPCCommand commands[] =
     { "wallet",             "removeprunedfunds",                &removeprunedfunds,             {"txid"} },
     { "wallet",             "rescanblockchain",                 &rescanblockchain,              {"start_height", "stop_height"} },
     { "wallet",             "send",                             &send,                          {"outputs","conf_target","estimate_mode","options"} },
-    { "wallet",             "sendmany",                         &sendmany,                      {"dummy","amounts","minconf","comment","subtractfeefrom","replaceable","conf_target","estimate_mode"} },
-    { "wallet",             "sendtoaddress",                    &sendtoaddress,                 {"address","amount","comment","comment_to","subtractfeefromamount","replaceable","conf_target","estimate_mode","avoid_reuse"} },
+    { "wallet",             "sendmany",                         &sendmany,                      {"dummy","amounts","minconf","comment","subtractfeefrom","replaceable","conf_target","estimate_mode","verbose"} },
+    { "wallet",             "sendtoaddress",                    &sendtoaddress,                 {"address","amount","comment","comment_to","subtractfeefromamount","replaceable","conf_target","estimate_mode","avoid_reuse","verbose"} },
     { "wallet",             "sethdseed",                        &sethdseed,                     {"newkeypool","seed"} },
     { "wallet",             "setlabel",                         &setlabel,                      {"address","label"} },
     { "wallet",             "settxfee",                         &settxfee,                      {"amount"} },
diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 4393bb7701..c42114c394 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -524,8 +524,9 @@ public:
         int changePos = -1;
         bilingual_str error;
         CCoinControl dummy;
+        FeeCalculation fee_calc_out;
         {
-            BOOST_CHECK(wallet->CreateTransaction({recipient}, tx, fee, changePos, error, dummy));
+            BOOST_CHECK(wallet->CreateTransaction({recipient}, tx, fee, changePos, error, dummy, fee_calc_out));
         }
         wallet->CommitTransaction(tx, {}, {});
         CMutableTransaction blocktx;
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 6f320096eb..4d8c0b175b 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -2629,7 +2629,8 @@ bool CWallet::FundTransaction(CMutableTransaction& tx, CAmount& nFeeRet, int& nC
     LOCK(cs_wallet);
 
     CTransactionRef tx_new;
-    if (!CreateTransaction(vecSend, tx_new, nFeeRet, nChangePosInOut, error, coinControl, false)) {
+    FeeCalculation fee_calc_out;
+    if (!CreateTransaction(vecSend, tx_new, nFeeRet, nChangePosInOut, error, coinControl, fee_calc_out, false)) {
         return false;
     }
 
@@ -2753,6 +2754,7 @@ bool CWallet::CreateTransactionInternal(
         int& nChangePosInOut,
         bilingual_str& error,
         const CCoinControl& coin_control,
+        FeeCalculation& fee_calc_out,
         bool sign)
 {
     CAmount nValue = 0;
@@ -3096,6 +3098,7 @@ bool CWallet::CreateTransactionInternal(
     // Before we return success, we assume any change key will be used to prevent
     // accidental re-use.
     reservedest.KeepDestination();
+    fee_calc_out = feeCalc;
 
     WalletLogPrintf("Fee Calculation: Fee:%d Bytes:%u Needed:%d Tgt:%d (requested %d) Reason:\"%s\" Decay %.5f: Estimation: (%g - %g) %.2f%% %.1f/(%.1f %d mem %.1f out) Fail: (%g - %g) %.2f%% %.1f/(%.1f %d mem %.1f out)\n",
               nFeeRet, nBytes, nFeeNeeded, feeCalc.returnedTarget, feeCalc.desiredTarget, StringForFeeReason(feeCalc.reason), feeCalc.est.decay,
@@ -3115,11 +3118,12 @@ bool CWallet::CreateTransaction(
         int& nChangePosInOut,
         bilingual_str& error,
         const CCoinControl& coin_control,
+        FeeCalculation& fee_calc_out,
         bool sign)
 {
     int nChangePosIn = nChangePosInOut;
     CTransactionRef tx2 = tx;
-    bool res = CreateTransactionInternal(vecSend, tx, nFeeRet, nChangePosInOut, error, coin_control, sign);
+    bool res = CreateTransactionInternal(vecSend, tx, nFeeRet, nChangePosInOut, error, coin_control, fee_calc_out, sign);
     // try with avoidpartialspends unless it's enabled already
     if (res && nFeeRet > 0 /* 0 means non-functional fee rate estimation */ && m_max_aps_fee > -1 && !coin_control.m_avoid_partial_spends) {
         CCoinControl tmp_cc = coin_control;
@@ -3127,7 +3131,7 @@ bool CWallet::CreateTransaction(
         CAmount nFeeRet2;
         int nChangePosInOut2 = nChangePosIn;
         bilingual_str error2; // fired and forgotten; if an error occurs, we discard the results
-        if (CreateTransactionInternal(vecSend, tx2, nFeeRet2, nChangePosInOut2, error2, tmp_cc, sign)) {
+        if (CreateTransactionInternal(vecSend, tx2, nFeeRet2, nChangePosInOut2, error2, tmp_cc, fee_calc_out, sign)) {
             // if fee of this alternative one is within the range of the max fee, we use this one
             const bool use_aps = nFeeRet2 <= nFeeRet + m_max_aps_fee;
             WalletLogPrintf("Fee non-grouped = %lld, grouped = %lld, using %s\n", nFeeRet, nFeeRet2, use_aps ? "grouped" : "non-grouped");
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 169f266980..fb08cb4085 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -723,7 +723,7 @@ private:
     // ScriptPubKeyMan::GetID. In many cases it will be the hash of an internal structure
     std::map<uint256, std::unique_ptr<ScriptPubKeyMan>> m_spk_managers;
 
-    bool CreateTransactionInternal(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CAmount& nFeeRet, int& nChangePosInOut, bilingual_str& error, const CCoinControl& coin_control, bool sign);
+    bool CreateTransactionInternal(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CAmount& nFeeRet, int& nChangePosInOut, bilingual_str& error, const CCoinControl& coin_control, FeeCalculation& fee_calc_out, bool sign);
 
 public:
     /*
@@ -974,7 +974,7 @@ public:
      * selected by SelectCoins(); Also create the change output, when needed
      * @note passing nChangePosInOut as -1 will result in setting a random position
      */
-    bool CreateTransaction(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CAmount& nFeeRet, int& nChangePosInOut, bilingual_str& error, const CCoinControl& coin_control, bool sign = true);
+    bool CreateTransaction(const std::vector<CRecipient>& vecSend, CTransactionRef& tx, CAmount& nFeeRet, int& nChangePosInOut, bilingual_str& error, const CCoinControl& coin_control, FeeCalculation& fee_calc_out, bool sign = true);
     /**
      * Submit the transaction to the node's mempool and then relay to peers.
      * Should be called after CreateTransaction unless you want to abort
diff --git a/test/functional/wallet_basic.py b/test/functional/wallet_basic.py
index bb208341a0..68498fdbf8 100755
--- a/test/functional/wallet_basic.py
+++ b/test/functional/wallet_basic.py
@@ -661,6 +661,17 @@ class WalletTest(BitcoinTestFramework):
         assert_array_result(tx["details"], {"category": "receive"}, expected_receive_vout)
         assert_equal(tx[verbose_field], self.nodes[0].decoderawtransaction(tx["hex"]))
 
+        self.log.info("Test send* RPCs with verbose=True")
+        address = self.nodes[0].getnewaddress("test")
+        txid_feeReason_one = self.nodes[2].sendtoaddress(address = address, amount = 5, verbose = True)
+        assert_equal(txid_feeReason_one["fee_reason"], "Fallback fee")
+        txid_feeReason_two = self.nodes[2].sendmany(dummy = '', amounts = {address: 5}, verbose = True)
+        assert_equal(txid_feeReason_two["fee_reason"], "Fallback fee")
+        self.log.info("Test send* RPCs with verbose=False")
+        txid_feeReason_three = self.nodes[2].sendtoaddress(address = address, amount = 5, verbose = False)
+        assert_equal(self.nodes[2].gettransaction(txid_feeReason_three)['txid'], txid_feeReason_three)
+        txid_feeReason_four = self.nodes[2].sendmany(dummy = '', amounts = {address: 5}, verbose = False)
+        assert_equal(self.nodes[2].gettransaction(txid_feeReason_four)['txid'], txid_feeReason_four)
 
 if __name__ == '__main__':
     WalletTest().main()