[WIP] Start implementing LoanSet transactor

- Add some more values and functions to make it easier to work with
  basis point values / bips.
- Fix several earlier mistakes.

include/xrpl/protocol/Protocol.h

@@ -82,30 +82,86 @@ std::size_t constexpr maxDeletableTokenOfferEntries = 500;
  */
 std::uint16_t constexpr maxTransferFee = 50000;
 
-/** The maximum management fee rate allowed in lending.
+/** There are 10,000 basis points (bips) in 100%.
-
+ *
-    TODO: Is this a good name?
+ * Basis points represent 0.01%.
-
+ *
-    Valid values for the the management fee charged by the Lending Protocol are
+ * Given a value X, to find the amount for B bps,
-    between 0 and 10000 inclusive. A value of 1 is equivalent to 1/10 basis
+ * use X * B / bipsPerUnity
-    point fee or 0.001%.
+ *
+ * Example: If a loan broker has 999 XRP of debt, and must maintain 1,000 bps of
+ * that debt as cover (10%), then the minimum cover amount is 999,000,000 drops
+ * * 1000 / bipsPerUnity = 99,900,00 drops or 99.9 XRP.
+ *
+ * Given a percentage P, to find the number of bps that percentage represents,
+ * use P * bipsPerUnity.
+ *
+ * Example: 50% is 0.50 * bipsPerUnity = 5,000 bps.
  */
-std::uint16_t constexpr maxFeeRate = 10'000;
+std::uint32_t constexpr bipsPerUnity = 100 * 100;
+std::uint32_t constexpr tenthBipsPerUnity = bipsPerUnity * 10;
 
-/** The maximum coverage rate allowed in lending.
+constexpr std::uint32_t
+percentageToBips(std::uint32_t percentage)
+{
+    return percentage * bipsPerUnity / 100;
+}
+constexpr std::uint32_t
+percentageToTenthBips(std::uint32_t percentage)
+{
+    return percentage * tenthBipsPerUnity / 100;
+}
+template <typename T>
+constexpr T
+bipsOfValue(T value, std::uint32_t bips)
+{
+    return value * bips / bipsPerUnity;
+}
+template <typename T>
+constexpr T
+tenthBipsOfValue(T value, std::uint32_t bips)
+{
+    return value * bips / tenthBipsPerUnity;
+}
 
-    TODO: Is this a good name?
+/** The maximum management fee rate allowed by a loan broker in 1/10 bips.
 
-    Valid values for the coverage rate charged by the Lending Protocol for first
+    Valid values are between 0 and 10% inclusive.
-    loss capital operations are between 0 and 100000 inclusive. A value of 1 is
-    equivalent to 1/10 bps or 0.001%.
 */
-std::uint32_t constexpr maxCoverRate = 100'000;
+std::uint16_t constexpr maxManagementFeeRate = percentageToTenthBips(10);
+static_assert(maxManagementFeeRate == 10'000);
 
-/** Basis points (bps) represent 0.01% of a thing. Given a value X, to find the
+/** The maximum coverage rate required of a loan broker in 1/10 bips.
- * amount for B bps, use X * B / bpsPerOne
+
+    Valid values are between 0 and 100% inclusive.
 */
-std::uint32_t constexpr bpsPerOne = 10'000;
+std::uint32_t constexpr maxCoverRate = percentageToTenthBips(100);
+static_assert(maxCoverRate == 100'000);
+
+/** The maximum overpayment fee on a loan in 1/10 bips.
+*
+    Valid values are between 0 and 100% inclusive.
+*/
+std::uint32_t constexpr maxOverpaymentFee = percentageToTenthBips(100);
+
+/** The maximum premium added to the interest rate for late payments on a loan
+ * in 1/10 bips.
+ *
+ * Valid values are between 0 and 100% inclusive.
+ */
+std::uint32_t constexpr maxLateInterestRate = percentageToTenthBips(100);
+
+/** The maximum interest rate charged for repaying a loan early in 1/10 bips.
+ *
+ * Valid values are between 0 and 100% inclusive.
+ */
+std::uint32_t constexpr maxCloseInterestRate = percentageToTenthBips(100);
+
+/** The maximum interest rate charged on loan overpayments in 1/10 bips.
+ *
+ * Valid values are between 0 and 100% inclusive.
+ */
+std::uint32_t constexpr maxOverpaymentInterestRate = percentageToTenthBips(100);
 
 /** The maximum length of a URI inside an NFT */
 std::size_t constexpr maxTokenURILength = 256;

include/xrpl/protocol/TxFlags.h

@@ -234,14 +234,14 @@ constexpr std::uint32_t const tfVaultShareNonTransferable  = 0x00020000;
 constexpr std::uint32_t const tfVaultCreateMask = ~(tfUniversal | tfVaultPrivate | tfVaultShareNonTransferable);
 
 // LoanSet flags:
-// True, indicates the load supports overpayments
+// True, indicates the loan supports overpayments
 constexpr std::uint32_t const tfLoanOverpayment = 0x00010000;
 constexpr std::uint32_t const tfLoanSetMask = ~(tfUniversal | tfLoanOverpayment);
 
 // LoanManage flags:
 constexpr std::uint32_t const tfLoanDefault = 0x00010000;
-constexpr std::uint32_t const tfLoanImpair = 0x00010000;
+constexpr std::uint32_t const tfLoanImpair = 0x00020000;
-constexpr std::uint32_t const tfLoanUnimpair = 0x00010000;
+constexpr std::uint32_t const tfLoanUnimpair = 0x00040000;
 constexpr std::uint32_t const tfLoanManageMask = ~(tfUniversal | tfLoanDefault | tfLoanImpair | tfLoanUnimpair);
 
 // clang-format on

include/xrpl/protocol/detail/sfields.macro

@@ -24,6 +24,8 @@
 #error "undefined macro: TYPED_SFIELD"
 #endif
 
+// clang-format off
+
 // untyped
 UNTYPED_SFIELD(sfLedgerEntry,            LEDGERENTRY, 257)
 UNTYPED_SFIELD(sfTransaction,            TRANSACTION, 257)
@@ -60,10 +62,6 @@ TYPED_SFIELD(sfHookExecutionIndex,       UINT16,    19)
 TYPED_SFIELD(sfHookApiVersion,           UINT16,    20)
 TYPED_SFIELD(sfLedgerFixType,            UINT16,    21)
 TYPED_SFIELD(sfManagementFeeRate,        UINT16,    22)
-TYPED_SFIELD(sfInterestRate,             UINT16,    25)
-TYPED_SFIELD(sfLateInterestRate,         UINT16,    26)
-TYPED_SFIELD(sfCloseInterestRate,        UINT16,    27)
-TYPED_SFIELD(sfOverpaymentInterestRate,  UINT16,    28)
 
 // 32-bit integers (common)
 TYPED_SFIELD(sfNetworkID,                UINT32,     1)
@@ -127,6 +125,10 @@ TYPED_SFIELD(sfPaymentRemaining,         UINT32,    57)
 TYPED_SFIELD(sfPaymentTotal,             UINT32,    58)
 TYPED_SFIELD(sfCoverRateMinimum,         UINT32,    59)
 TYPED_SFIELD(sfCoverRateLiquidation,     UINT32,    60)
+TYPED_SFIELD(sfInterestRate,             UINT32,    61)
+TYPED_SFIELD(sfLateInterestRate,         UINT32,    62)
+TYPED_SFIELD(sfCloseInterestRate,        UINT32,    63)
+TYPED_SFIELD(sfOverpaymentInterestRate,  UINT32,    64)
 
 // 64-bit integers (common)
 TYPED_SFIELD(sfIndexNext,                UINT64,     1)
@@ -418,3 +420,5 @@ UNTYPED_SFIELD(sfAuthAccounts,           ARRAY,     25)
 UNTYPED_SFIELD(sfAuthorizeCredentials,   ARRAY,     26)
 UNTYPED_SFIELD(sfUnauthorizeCredentials, ARRAY,     27)
 UNTYPED_SFIELD(sfAcceptedCredentials,    ARRAY,     28)
+
+// clang-format on

include/xrpl/protocol/detail/transactions.macro

@@ -726,7 +726,6 @@ TRANSACTION(ttLOAN_BROKER_COVER_WITHDRAW, 77, LoanBrokerCoverWithdraw, noPriv, (
     {sfAmount, soeREQUIRED, soeMPTSupported},
 }))
 
-#if 0
 /** This transaction creates a Loan */
 #if TRANSACTION_INCLUDE
 #   include <xrpld/app/tx/detail/LoanSet.h>
@@ -750,6 +749,7 @@ TRANSACTION(ttLOAN_SET, 78, LoanSet, noPriv, ({
     {sfGracePeriod, soeOPTIONAL},
 }))
 
+#if 0
 /** This transaction deletes an existing Loan */
 #if TRANSACTION_INCLUDE
 #   include <xrpld/app/tx/detail/LoanDelete.h>

src/libxrpl/protocol/InnerObjectFormats.cpp

@@ -28,12 +28,6 @@ InnerObjectFormats::InnerObjectFormats()
     // inner objects with the default fields have to be
     // constructed with STObject::makeInnerObject()
 
-    std::initializer_list<SOElement> const signingFields = {
-        {sfAccount, soeREQUIRED},
-        {sfSigningPubKey, soeREQUIRED},
-        {sfTxnSignature, soeREQUIRED},
-    };
-
     add(sfSignerEntry.jsonName,
         sfSignerEntry.getCode(),
         {
@@ -42,7 +36,13 @@ InnerObjectFormats::InnerObjectFormats()
             {sfWalletLocator, soeOPTIONAL},
         });
 
-    add(sfSigner.jsonName, sfSigner.getCode(), signingFields);
+    add(sfSigner.jsonName,
+        sfSigner.getCode(),
+        {
+            {sfAccount, soeREQUIRED},
+            {sfSigningPubKey, soeREQUIRED},
+            {sfTxnSignature, soeREQUIRED},
+        });
 
     add(sfMajority.jsonName,
         sfMajority.getCode(),
@@ -157,7 +157,11 @@ InnerObjectFormats::InnerObjectFormats()
 
     add(sfCounterpartySignature.jsonName,
         sfCounterpartySignature.getCode(),
-        signingFields);
+        {
+            {sfSigningPubKey, soeREQUIRED},
+            {sfTxnSignature, soeOPTIONAL},
+            {sfSigners, soeOPTIONAL},
+        });
 }
 
 InnerObjectFormats const&

src/test/app/LoanBroker_test.cpp

@@ -416,12 +416,12 @@ class LoanBroker_test : public beast::unit_test::suite
                 ter(temINVALID));
             // sfManagementFeeRate: good value, bad account
             env(set(evan, vault.vaultID),
-                managementFeeRate(maxFeeRate),
+                managementFeeRate(maxManagementFeeRate),
                 fee(increment),
                 ter(tecNO_PERMISSION));
             // sfManagementFeeRate: too big
             env(set(evan, vault.vaultID),
-                managementFeeRate(maxFeeRate + 1),
+                managementFeeRate(maxManagementFeeRate + 1),
                 fee(increment),
                 ter(temINVALID));
             // sfCoverRateMinimum: good value, bad account
@@ -504,17 +504,17 @@ class LoanBroker_test : public beast::unit_test::suite
                     // ManagementFeeRate
                     env(set(alice, vault.vaultID),
                         loanBrokerID(broker->key()),
-                        managementFeeRate(maxFeeRate),
+                        managementFeeRate(maxManagementFeeRate),
                         ter(temINVALID));
                     // CoverRateMinimum
                     env(set(alice, vault.vaultID),
                         loanBrokerID(broker->key()),
-                        coverRateMinimum(maxFeeRate),
+                        coverRateMinimum(maxManagementFeeRate),
                         ter(temINVALID));
                     // CoverRateLiquidation
                     env(set(alice, vault.vaultID),
                         loanBrokerID(broker->key()),
-                        coverRateLiquidation(maxFeeRate),
+                        coverRateLiquidation(maxManagementFeeRate),
                         ter(temINVALID));
 
                     // fields that can be changed

src/xrpld/app/tx/detail/LoanBrokerCoverWithdraw.cpp

@@ -109,9 +109,9 @@ LoanBrokerCoverWithdraw::preclaim(PreclaimContext const& ctx)
     }
 
     auto const coverAvail = sleBroker->at(sfCoverAvailable);
-    // Cover Rate is in 1/10 bps units
+    // Cover Rate is in 1/10 bips units
-    auto const minimumCover = sleBroker->at(sfDebtTotal) *
+    auto const minimumCover = tenthBipsOfValue(
-        sleBroker->at(sfCoverRateMinimum) / bpsPerOne / 10;
+        sleBroker->at(sfDebtTotal), sleBroker->at(sfCoverRateMinimum));
     if (coverAvail < amount)
         return tecINSUFFICIENT_FUNDS;
     if ((coverAvail - amount) < minimumCover)

src/xrpld/app/tx/detail/LoanBrokerSet.cpp

@@ -69,7 +69,7 @@ LoanBrokerSet::doPreflight(PreflightContext const& ctx)
     if (auto const data = tx[~sfData]; data && !data->empty() &&
         !validDataLength(tx[~sfData], maxDataPayloadLength))
         return temINVALID;
-    if (!validNumericRange(tx[~sfManagementFeeRate], maxFeeRate))
+    if (!validNumericRange(tx[~sfManagementFeeRate], maxManagementFeeRate))
         return temINVALID;
     if (!validNumericRange(tx[~sfCoverRateMinimum], maxCoverRate))
         return temINVALID;

src/xrpld/app/tx/detail/LoanSet.cpp

@@ -0,0 +1,213 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2025 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <xrpld/app/tx/detail/LoanSet.h>
+//
+#include <xrpld/app/tx/detail/LoanBrokerSet.h>
+#include <xrpld/app/tx/detail/SignerEntries.h>
+#include <xrpld/app/tx/detail/VaultCreate.h>
+#include <xrpld/ledger/ApplyView.h>
+#include <xrpld/ledger/View.h>
+
+#include <xrpl/basics/Log.h>
+#include <xrpl/basics/Number.h>
+#include <xrpl/basics/chrono.h>
+#include <xrpl/beast/utility/Journal.h>
+#include <xrpl/beast/utility/instrumentation.h>
+#include <xrpl/protocol/AccountID.h>
+#include <xrpl/protocol/Feature.h>
+#include <xrpl/protocol/Indexes.h>
+#include <xrpl/protocol/PublicKey.h>
+#include <xrpl/protocol/SField.h>
+#include <xrpl/protocol/STAmount.h>
+#include <xrpl/protocol/STNumber.h>
+#include <xrpl/protocol/STObject.h>
+#include <xrpl/protocol/STXChainBridge.h>
+#include <xrpl/protocol/TER.h>
+#include <xrpl/protocol/TxFlags.h>
+#include <xrpl/protocol/XRPAmount.h>
+
+namespace ripple {
+
+bool
+LoanSet::isEnabled(PreflightContext const& ctx)
+{
+    return lendingProtocolEnabled(ctx);
+}
+
+std::uint32_t
+LoanSet::getFlagsMask(PreflightContext const& ctx)
+{
+    return tfLoanSetMask;
+}
+
+NotTEC
+LoanSet::doPreflight(PreflightContext const& ctx)
+{
+    auto const& tx = ctx.tx;
+    if (auto const data = tx[~sfData]; data && !data->empty() &&
+        !validDataLength(tx[~sfData], maxDataPayloadLength))
+        return temINVALID;
+    if (!validNumericRange(tx[~sfLateInterestRate], maxLateInterestRate))
+        return temINVALID;
+    if (!validNumericRange(tx[~sfCloseInterestRate], maxCloseInterestRate))
+        return temINVALID;
+    if (!validNumericRange(
+            tx[~sfOverpaymentInterestRate], maxOverpaymentInterestRate))
+        return temINVALID;
+
+    if (auto const paymentTotal = tx[~sfPaymentTotal];
+        paymentTotal && *paymentTotal == 0)
+        return temINVALID;
+    if (auto const paymentInterval =
+            tx[~sfPaymentInterval].value_or(LoanSet::defaultPaymentInterval);
+        paymentInterval < LoanSet::defaultPaymentInterval)
+        return temINVALID;
+    else if (auto const gracePeriod =
+                 tx[~sfGracePeriod].value_or(LoanSet::defaultGracePeriod);
+             gracePeriod > paymentInterval)
+        return temINVALID;
+
+    return tesSUCCESS;
+}
+
+TER
+LoanSet::preclaim(PreclaimContext const& ctx)
+{
+    return temDISABLED;
+
+    auto const& tx = ctx.tx;
+
+    auto const account = tx[sfAccount];
+    if (auto const ID = tx[~sfLoanID])
+    {
+        auto const sle = ctx.view.read(keylet::loan(*ID));
+        if (!sle)
+        {
+            JLOG(ctx.j.warn()) << "Loan does not exist.";
+            return tecNO_ENTRY;
+        }
+        if (tx[sfVaultID] != sle->at(sfVaultID))
+        {
+            JLOG(ctx.j.warn()) << "Can not change VaultID on an existing Loan.";
+            return tecNO_PERMISSION;
+        }
+        if (account != sle->at(sfOwner))
+        {
+            JLOG(ctx.j.warn()) << "Account is not the owner of the Loan.";
+            return tecNO_PERMISSION;
+        }
+    }
+    else
+    {
+        auto const vaultID = tx[sfVaultID];
+        auto const sleVault = ctx.view.read(keylet::vault(vaultID));
+        if (!sleVault)
+        {
+            JLOG(ctx.j.warn()) << "Vault does not exist.";
+            return tecNO_ENTRY;
+        }
+        if (account != sleVault->at(sfOwner))
+        {
+            JLOG(ctx.j.warn()) << "Account is not the owner of the Vault.";
+            return tecNO_PERMISSION;
+        }
+    }
+    return tesSUCCESS;
+}
+
+TER
+LoanSet::doApply()
+{
+    return temDISABLED;
+
+    auto const& tx = ctx_.tx;
+    auto& view = ctx_.view();
+
+#if 0
+    if (auto const ID = tx[~sfLoanID])
+    {
+        // Modify an existing Loan
+        auto loan = view.peek(keylet::loan(*ID));
+
+        if (auto const data = tx[~sfData])
+            loan->at(sfData) = *data;
+        if (auto const debtMax = tx[~sfDebtMaximum])
+            loan->at(sfDebtMaximum) = *debtMax;
+
+        view.update();
+    }
+    else
+    {
+        // Create a new Loan pointing back to the given Vault
+        auto const vaultID = tx[sfVaultID];
+        auto const sleVault = view.read(keylet::vault(vaultID));
+        auto const vaultPseudoID = sleVault->at(sfAccount);
+        auto const sequence = tx.getSeqValue();
+
+        auto owner = view.peek(keylet::account(account_));
+        auto loan = std::make_shared<SLE>(keylet::loan(account_, sequence));
+
+        if (auto const ter = dirLink(view, account_, ))
+            return ter;
+        if (auto const ter = dirLink(view, vaultPseudoID, , sfVaultNode))
+            return ter;
+
+        adjustOwnerCount(view, owner, 1, j_);
+        auto ownerCount = owner->at(sfOwnerCount);
+        if (mPriorBalance < view.fees().accountReserve(ownerCount))
+            return tecINSUFFICIENT_RESERVE;
+
+        auto maybePseudo =
+            createPseudoAccount(view, loan->key(), PseudoAccountOwnerType::Loan);
+        if (!maybePseudo)
+            return maybePseudo.error();
+        auto& pseudo = *maybePseudo;
+        auto pseudoId = pseudo->at(sfAccount);
+
+        if (auto ter = addEmptyHolding(
+                view, pseudoId, mPriorBalance, sleVault->at(sfAsset), j_))
+            return ter;
+
+        // Initialize data fields:
+        loan->at(sfSequence) = sequence;
+        loan->at(sfVaultID) = vaultID;
+        loan->at(sfOwner) = account_;
+        loan->at(sfAccount) = pseudoId;
+        if (auto const data = tx[~sfData])
+            loan->at(sfData) = *data;
+        if (auto const rate = tx[~sfManagementFeeRate])
+            loan->at(sfManagementFeeRate) = *rate;
+        if (auto const debtMax = tx[~sfDebtMaximum])
+            loan->at(sfDebtMaximum) = *debtMax;
+        if (auto const coverMin = tx[~sfCoverRateMinimum])
+            loan->at(sfCoverRateMinimum) = *coverMin;
+        if (auto const coverLiq = tx[~sfCoverRateLiquidation])
+            loan->at(sfCoverRateLiquidation) = *coverLiq;
+
+        view.insert(loan);
+    }
+#endif
+
+    return tesSUCCESS;
+}
+
+//------------------------------------------------------------------------------
+
+}  // namespace ripple

src/xrpld/app/tx/detail/LoanSet.h

@@ -0,0 +1,61 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2025 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#ifndef RIPPLE_TX_LOANSET_H_INCLUDED
+#define RIPPLE_TX_LOANSET_H_INCLUDED
+
+#include <xrpld/app/tx/detail/Transactor.h>
+
+namespace ripple {
+
+class LoanSet : public Transactor
+{
+public:
+    static constexpr ConsequencesFactoryType ConsequencesFactory{Normal};
+
+    explicit LoanSet(ApplyContext& ctx) : Transactor(ctx)
+    {
+    }
+
+    static bool
+    isEnabled(PreflightContext const& ctx);
+
+    static std::uint32_t
+    getFlagsMask(PreflightContext const& ctx);
+
+    static NotTEC
+    doPreflight(PreflightContext const& ctx);
+
+    static TER
+    preclaim(PreclaimContext const& ctx);
+
+    TER
+    doApply() override;
+
+private:
+    static std::uint32_t constexpr defaultPaymentTotal = 1;
+    static std::uint32_t constexpr defaultPaymentInterval = 60;
+    static std::uint32_t constexpr defaultGracePeriod = 60;
+};
+
+//------------------------------------------------------------------------------
+
+}  // namespace ripple
+
+#endif