LoanBrokerSet.cpp

#include <xrpl/tx/transactors/lending/LoanBrokerSet.h>
 
#include <xrpl/basics/Log.h>
#include <xrpl/basics/Number.h>
#include <xrpl/beast/utility/Zero.h>
#include <xrpl/core/ServiceRegistry.h>
#include <xrpl/ledger/View.h>
#include <xrpl/ledger/helpers/AccountRootHelpers.h>
#include <xrpl/ledger/helpers/LendingHelpers.h>
#include <xrpl/ledger/helpers/TokenHelpers.h>
#include <xrpl/ledger/helpers/VaultHelpers.h>
#include <xrpl/protocol/Asset.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/Protocol.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STLedgerEntry.h>
#include <xrpl/protocol/STNumber.h>
#include <xrpl/protocol/STTakesAsset.h>
#include <xrpl/protocol/STTx.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/XRPAmount.h>
#include <xrpl/tx/Transactor.h>
 
#include <memory>
#include <vector>
 
namespace xrpl {
 
bool
LoanBrokerSet::checkExtraFeatures(PreflightContext const& ctx)
{
    return checkLendingProtocolDependencies(ctx.rules, ctx.tx);
}
 
NotTEC
LoanBrokerSet::preflight(PreflightContext const& ctx)
{
    using namespace lending;
 
    auto const& tx = ctx.tx;
    if (auto const data = tx[~sfData];
        data && !data->empty() && !validDataLength(tx[~sfData], kMaxDataPayloadLength))
        return temINVALID;
    if (!validNumericRange(tx[~sfManagementFeeRate], kMaxManagementFeeRate))
        return temINVALID;
    if (!validNumericRange(tx[~sfCoverRateMinimum], kMaxCoverRate))
        return temINVALID;
    if (!validNumericRange(tx[~sfCoverRateLiquidation], kMaxCoverRate))
        return temINVALID;
    if (!validNumericRange(tx[~sfDebtMaximum], Number(kMaxMpTokenAmount), Number(0)))
        return temINVALID;
 
    if (tx.isFieldPresent(sfLoanBrokerID))
    {
        // Fixed fields can not be specified if we're modifying an existing
        // LoanBroker Object
        if (tx.isFieldPresent(sfManagementFeeRate) || tx.isFieldPresent(sfCoverRateMinimum) ||
            tx.isFieldPresent(sfCoverRateLiquidation))
            return temINVALID;
 
        if (tx[sfLoanBrokerID] == beast::kZero)
            return temINVALID;
    }
 
    if (auto const vaultID = tx.at(~sfVaultID))
    {
        if (*vaultID == beast::kZero)
            return temINVALID;
    }
 
    {
        auto const minimumZero = tx[~sfCoverRateMinimum].value_or(0) == 0;
        auto const liquidationZero = tx[~sfCoverRateLiquidation].value_or(0) == 0;
        // Both must be zero or non-zero.
        if (minimumZero != liquidationZero)
        {
            return temINVALID;
        }
    }
 
    return tesSUCCESS;
}
 
std::vector<OptionaledField<STNumber>> const&
LoanBrokerSet::getValueFields()
{
    static std::vector<OptionaledField<STNumber>> const kValueFields{~sfDebtMaximum};
 
    return kValueFields;
}
 
TER
LoanBrokerSet::preclaim(PreclaimContext const& ctx)
{
    auto const& tx = ctx.tx;
 
    auto const account = tx[sfAccount];
    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;
    }
    Asset const asset = sleVault->at(sfAsset);
 
    if (account != sleVault->at(sfOwner))
    {
        JLOG(ctx.j.warn()) << "Account is not the owner of the Vault.";
        return tecNO_PERMISSION;
    }
 
    if (auto const brokerID = tx[~sfLoanBrokerID])
    {
        // Updating an existing Broker
 
        auto const sleBroker = ctx.view.read(keylet::loanBroker(*brokerID));
        if (!sleBroker)
        {
            JLOG(ctx.j.warn()) << "LoanBroker does not exist.";
            return tecNO_ENTRY;
        }
        if (vaultID != sleBroker->at(sfVaultID))
        {
            JLOG(ctx.j.warn()) << "Can not change VaultID on an existing LoanBroker.";
            return tecNO_PERMISSION;
        }
        if (account != sleBroker->at(sfOwner))
        {
            JLOG(ctx.j.warn()) << "Account is not the owner of the LoanBroker.";
            return tecNO_PERMISSION;
        }
 
        if (auto const debtMax = tx[~sfDebtMaximum])
        {
            // Can't reduce the debt maximum below the current total debt
            auto const currentDebtTotal = sleBroker->at(sfDebtTotal);
            if (*debtMax != 0 && *debtMax < currentDebtTotal)
            {
                JLOG(ctx.j.warn()) << "Cannot reduce DebtMaximum below current DebtTotal.";
                return tecLIMIT_EXCEEDED;
            }
        }
    }
    else
    {
        // LP V1.1: only closed-ended vaults may host a loan broker. The
        // lending protocol relies on the closed-ended Subscription /
        // Investment / Redemption phase structure; attaching a broker to
        // an open-ended vault has no well-defined lifecycle. VaultCreate
        // stays unrestricted so existing open-ended flows keep working;
        // the constraint is enforced here, at the point where the vault
        // is first bound to the lending protocol.
        if (ctx.view.rules().enabled(featureLendingProtocolV1_1) &&
            getVaultKind(sleVault) != VaultKind::ClosedEnded)
        {
            JLOG(ctx.j.warn()) << "LoanBroker requires a closed-ended Vault.";
            return tecNO_PERMISSION;
        }
 
        if (auto const ter = canAddHolding(ctx.view, asset))
            return ter;
 
        if (auto const ter = checkFrozen(ctx.view, sleVault->at(sfAccount), sleVault->at(sfAsset)))
        {
            JLOG(ctx.j.warn()) << "Vault pseudo-account is frozen.";
            return ter;
        }
    }
 
    // Check that relevant values can be represented as the vault asset
    // type. This is mostly only relevant for integral (non-IOU) types
    for (auto const& field : getValueFields())
    {
        if (auto const value = tx[field]; value && STAmount{asset, *value} != *value)
        {
            JLOG(ctx.j.warn()) << field.f->getName() << " (" << *value
                               << ") can not be represented as a(n) " << to_string(asset) << ".";
            return tecPRECISION_LOSS;
        }
    }
 
    return tesSUCCESS;
}
 
TER
LoanBrokerSet::doApply()
{
    auto const& tx = ctx_.tx;
    auto& view = ctx_.view();
 
    if (auto const brokerID = tx[~sfLoanBrokerID])
    {
        // Modify an existing LoanBroker
        auto broker = view.peek(keylet::loanBroker(*brokerID));
        if (!broker)
        {
            // This should be impossible
            // LCOV_EXCL_START
            JLOG(j_.fatal()) << "LoanBroker does not exist.";
            return tefBAD_LEDGER;
            // LCOV_EXCL_STOP
        }
 
        auto const vault = view.read(keylet::vault(broker->at(sfVaultID)));
        if (!vault)
            return tecINTERNAL;  // LCOV_EXCL_LINE
 
        auto const vaultAsset = vault->at(sfAsset);
 
        if (auto const data = tx[~sfData])
            broker->at(sfData) = *data;
        if (auto const debtMax = tx[~sfDebtMaximum])
            broker->at(sfDebtMaximum) = *debtMax;
 
        view.update(broker);
 
        associateAsset(*broker, vaultAsset);
    }
    else
    {
        // Create a new LoanBroker pointing back to the given Vault
        auto const vaultID = tx[sfVaultID];
        auto const sleVault = view.read(keylet::vault(vaultID));
        if (!sleVault)
        {
            // This should be impossible
            // LCOV_EXCL_START
            JLOG(j_.fatal()) << "Vault does not exist.";
            return tefBAD_LEDGER;
            // LCOV_EXCL_STOP
        }
        auto const vaultPseudoID = sleVault->at(sfAccount);
        auto const vaultAsset = sleVault->at(sfAsset);
        auto const sequence = tx.getSeqProxy();
 
        auto owner = view.peek(keylet::account(accountID_));
        if (!owner)
        {
            // This should be impossible
            // LCOV_EXCL_START
            JLOG(j_.fatal()) << "Account does not exist.";
            return tefBAD_LEDGER;
            // LCOV_EXCL_STOP
        }
        auto broker = std::make_shared<SLE>(keylet::loanBroker(accountID_, sequence));
 
        if (auto const ter = dirLink(view, accountID_, broker))
            return ter;  // LCOV_EXCL_LINE
        if (auto const ter = dirLink(view, vaultPseudoID, broker, sfVaultNode))
            return ter;  // LCOV_EXCL_LINE
 
        // Increases the owner count by two: one for the LoanBroker object, and
        // one for the pseudo-account.
        increaseOwnerCount(view, owner, {}, 2, j_);
        if (preFeeBalance_ < accountReserve(view, owner, j_))
            return tecINSUFFICIENT_RESERVE;
 
        auto maybePseudo = createPseudoAccount(view, broker->key(), sfLoanBrokerID);
        if (!maybePseudo)
            return maybePseudo.error();  // LCOV_EXCL_LINE
        auto& pseudo = *maybePseudo;
        auto pseudoId = pseudo->at(sfAccount);
 
        if (auto ter = addEmptyHolding(
                ctx_.getApplyViewContext(), pseudoId, preFeeBalance_, sleVault->at(sfAsset), j_))
            return ter;
 
        // Initialize data fields:
        broker->at(sfSequence) = sequence.value();
        broker->at(sfVaultID) = vaultID;
        broker->at(sfOwner) = accountID_;
        broker->at(sfAccount) = pseudoId;
        // The LoanSequence indexes loans created by this broker, starting at 1
        broker->at(sfLoanSequence) = 1;
        if (auto const data = tx[~sfData])
            broker->at(sfData) = *data;
        if (auto const rate = tx[~sfManagementFeeRate])
            broker->at(sfManagementFeeRate) = *rate;
        if (auto const debtMax = tx[~sfDebtMaximum])
            broker->at(sfDebtMaximum) = *debtMax;
        if (auto const coverMin = tx[~sfCoverRateMinimum])
            broker->at(sfCoverRateMinimum) = *coverMin;
        if (auto const coverLiq = tx[~sfCoverRateLiquidation])
            broker->at(sfCoverRateLiquidation) = *coverLiq;
 
        view.insert(broker);
 
        associateAsset(*broker, vaultAsset);
    }
 
    return tesSUCCESS;
}
 
void
LoanBrokerSet::visitInvariantEntry(bool, SLE::ConstRef, SLE::ConstRef)
{
    // No transaction-specific invariants yet (future work).
}
 
bool
LoanBrokerSet::finalizeInvariants(
    STTx const&,
    TER,
    XRPAmount,
    ReadView const&,
    beast::Journal const&)
{
    // No transaction-specific invariants yet (future work).
    return true;
}
 
//------------------------------------------------------------------------------
 
}  // namespace xrpl