SetTrust.cpp

#include <xrpld/app/misc/DelegateUtils.h>
#include <xrpld/app/tx/detail/SetTrust.h>
 
#include <xrpl/basics/Log.h>
#include <xrpl/ledger/View.h>
#include <xrpl/protocol/AMMCore.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/Quality.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/TER.h>
 
namespace {
 
uint32_t
computeFreezeFlags(
    uint32_t uFlags,
    bool bHigh,
    bool bNoFreeze,
    bool bSetFreeze,
    bool bClearFreeze,
    bool bSetDeepFreeze,
    bool bClearDeepFreeze)
{
    if (bSetFreeze && !bClearFreeze && !bNoFreeze)
    {
        uFlags |= (bHigh ? xrpl::lsfHighFreeze : xrpl::lsfLowFreeze);
    }
    else if (bClearFreeze && !bSetFreeze)
    {
        uFlags &= ~(bHigh ? xrpl::lsfHighFreeze : xrpl::lsfLowFreeze);
    }
    if (bSetDeepFreeze && !bClearDeepFreeze && !bNoFreeze)
    {
        uFlags |= (bHigh ? xrpl::lsfHighDeepFreeze : xrpl::lsfLowDeepFreeze);
    }
    else if (bClearDeepFreeze && !bSetDeepFreeze)
    {
        uFlags &= ~(bHigh ? xrpl::lsfHighDeepFreeze : xrpl::lsfLowDeepFreeze);
    }
 
    return uFlags;
}
 
}  // namespace
 
namespace xrpl {
 
std::uint32_t
SetTrust::getFlagsMask(PreflightContext const& ctx)
{
    return tfTrustSetMask;
}
 
NotTEC
SetTrust::preflight(PreflightContext const& ctx)
{
    auto& tx = ctx.tx;
    auto& j = ctx.j;
 
    std::uint32_t const uTxFlags = tx.getFlags();
 
    if (!ctx.rules.enabled(featureDeepFreeze))
    {
        // Even though the deep freeze flags are included in the
        // `tfTrustSetMask`, they are not valid if the amendment is not enabled.
        if (uTxFlags & (tfSetDeepFreeze | tfClearDeepFreeze))
        {
            return temINVALID_FLAG;
        }
    }
 
    STAmount const saLimitAmount(tx.getFieldAmount(sfLimitAmount));
 
    if (!isLegalNet(saLimitAmount))
        return temBAD_AMOUNT;
 
    if (saLimitAmount.native())
    {
        JLOG(j.trace()) << "Malformed transaction: specifies native limit "
                        << saLimitAmount.getFullText();
        return temBAD_LIMIT;
    }
 
    if (badCurrency() == saLimitAmount.getCurrency())
    {
        JLOG(j.trace()) << "Malformed transaction: specifies XRP as IOU";
        return temBAD_CURRENCY;
    }
 
    if (saLimitAmount < beast::zero)
    {
        JLOG(j.trace()) << "Malformed transaction: Negative credit limit.";
        return temBAD_LIMIT;
    }
 
    // Check if destination makes sense.
    auto const& issuer = saLimitAmount.getIssuer();
 
    if (!issuer || issuer == noAccount())
    {
        JLOG(j.trace()) << "Malformed transaction: no destination account.";
        return temDST_NEEDED;
    }
 
    return tesSUCCESS;
}
 
NotTEC
SetTrust::checkPermission(ReadView const& view, STTx const& tx)
{
    auto const delegate = tx[~sfDelegate];
    if (!delegate)
        return tesSUCCESS;
 
    auto const delegateKey = keylet::delegate(tx[sfAccount], *delegate);
    auto const sle = view.read(delegateKey);
 
    if (!sle)
        return terNO_DELEGATE_PERMISSION;
 
    if (checkTxPermission(sle, tx) == tesSUCCESS)
        return tesSUCCESS;
 
    std::uint32_t const txFlags = tx.getFlags();
 
    // Currently we only support TrustlineAuthorize, TrustlineFreeze and
    // TrustlineUnfreeze granular permission. Setting other flags returns
    // error.
    if (txFlags & tfTrustSetPermissionMask)
        return terNO_DELEGATE_PERMISSION;
 
    if (tx.isFieldPresent(sfQualityIn) || tx.isFieldPresent(sfQualityOut))
        return terNO_DELEGATE_PERMISSION;
 
    auto const saLimitAmount = tx.getFieldAmount(sfLimitAmount);
    auto const sleRippleState = view.read(keylet::line(
        tx[sfAccount], saLimitAmount.getIssuer(), saLimitAmount.getCurrency()));
 
    // if the trustline does not exist, granular permissions are
    // not allowed to create trustline
    if (!sleRippleState)
        return terNO_DELEGATE_PERMISSION;
 
    std::unordered_set<GranularPermissionType> granularPermissions;
    loadGranularPermission(sle, ttTRUST_SET, granularPermissions);
 
    if (txFlags & tfSetfAuth &&
        !granularPermissions.contains(TrustlineAuthorize))
        return terNO_DELEGATE_PERMISSION;
    if (txFlags & tfSetFreeze && !granularPermissions.contains(TrustlineFreeze))
        return terNO_DELEGATE_PERMISSION;
    if (txFlags & tfClearFreeze &&
        !granularPermissions.contains(TrustlineUnfreeze))
        return terNO_DELEGATE_PERMISSION;
 
    // updating LimitAmount is not allowed only with granular permissions,
    // unless there's a new granular permission for this in the future.
    auto const curLimit = tx[sfAccount] > saLimitAmount.getIssuer()
        ? sleRippleState->getFieldAmount(sfHighLimit)
        : sleRippleState->getFieldAmount(sfLowLimit);
 
    STAmount saLimitAllow = saLimitAmount;
    saLimitAllow.setIssuer(tx[sfAccount]);
 
    if (curLimit != saLimitAllow)
        return terNO_DELEGATE_PERMISSION;
 
    return tesSUCCESS;
}
 
TER
SetTrust::preclaim(PreclaimContext const& ctx)
{
    auto const id = ctx.tx[sfAccount];
 
    auto const sle = ctx.view.read(keylet::account(id));
    if (!sle)
        return terNO_ACCOUNT;
 
    std::uint32_t const uTxFlags = ctx.tx.getFlags();
 
    bool const bSetAuth = (uTxFlags & tfSetfAuth);
 
    if (bSetAuth && !(sle->getFieldU32(sfFlags) & lsfRequireAuth))
    {
        JLOG(ctx.j.trace()) << "Retry: Auth not required.";
        return tefNO_AUTH_REQUIRED;
    }
 
    auto const saLimitAmount = ctx.tx[sfLimitAmount];
 
    auto const currency = saLimitAmount.getCurrency();
    auto const uDstAccountID = saLimitAmount.getIssuer();
 
    if (id == uDstAccountID)
        return temDST_IS_SRC;
 
    // This might be nullptr
    auto const sleDst = ctx.view.read(keylet::account(uDstAccountID));
    if ((ammEnabled(ctx.view.rules()) ||
         ctx.view.rules().enabled(featureSingleAssetVault)) &&
        sleDst == nullptr)
        return tecNO_DST;
 
    // If the destination has opted to disallow incoming trustlines
    // then honour that flag
    if (sleDst->getFlags() & lsfDisallowIncomingTrustline)
    {
        // The original implementation of featureDisallowIncoming was
        // too restrictive. If
        //   o fixDisallowIncomingV1 is enabled and
        //   o The trust line already exists
        // Then allow the TrustSet.
        if (ctx.view.rules().enabled(fixDisallowIncomingV1) &&
            ctx.view.exists(keylet::line(id, uDstAccountID, currency)))
        {
            // pass
        }
        else
            return tecNO_PERMISSION;
    }
 
    // In general, trust lines to pseudo accounts are not permitted, unless
    // enabled in the code section below, for specific cases. This block is not
    // amendment-gated because sleDst will not have a pseudo-account designator
    // field populated, unless the appropriate amendment was already enabled.
    if (sleDst && isPseudoAccount(sleDst))
    {
        // If destination is AMM and the trustline doesn't exist then only allow
        // SetTrust if the asset is AMM LP token and AMM is not in empty state.
        if (sleDst->isFieldPresent(sfAMMID))
        {
            if (ctx.view.exists(keylet::line(id, uDstAccountID, currency)))
            {
                // pass
            }
            else if (
                auto const ammSle =
                    ctx.view.read({ltAMM, sleDst->getFieldH256(sfAMMID)}))
            {
                if (auto const lpTokens =
                        ammSle->getFieldAmount(sfLPTokenBalance);
                    lpTokens == beast::zero)
                    return tecAMM_EMPTY;
                else if (lpTokens.getCurrency() != saLimitAmount.getCurrency())
                    return tecNO_PERMISSION;
            }
            else
                return tecINTERNAL;  // LCOV_EXCL_LINE
        }
        else if (
            sleDst->isFieldPresent(sfVaultID) ||
            sleDst->isFieldPresent(sfLoanBrokerID))
        {
            if (!ctx.view.exists(keylet::line(id, uDstAccountID, currency)))
                return tecNO_PERMISSION;
            // else pass
        }
        else
            return tecPSEUDO_ACCOUNT;
    }
 
    // Checking all freeze/deep freeze flag invariants.
    if (ctx.view.rules().enabled(featureDeepFreeze))
    {
        bool const bNoFreeze = sle->isFlag(lsfNoFreeze);
        bool const bSetFreeze = (uTxFlags & tfSetFreeze);
        bool const bSetDeepFreeze = (uTxFlags & tfSetDeepFreeze);
 
        if (bNoFreeze && (bSetFreeze || bSetDeepFreeze))
        {
            // Cannot freeze the trust line if NoFreeze is set
            return tecNO_PERMISSION;
        }
 
        bool const bClearFreeze = (uTxFlags & tfClearFreeze);
        bool const bClearDeepFreeze = (uTxFlags & tfClearDeepFreeze);
        if ((bSetFreeze || bSetDeepFreeze) &&
            (bClearFreeze || bClearDeepFreeze))
        {
            // Freezing and unfreezing in the same transaction should be
            // illegal
            return tecNO_PERMISSION;
        }
 
        bool const bHigh = id > uDstAccountID;
        // Fetching current state of trust line
        auto const sleRippleState =
            ctx.view.read(keylet::line(id, uDstAccountID, currency));
        std::uint32_t uFlags =
            sleRippleState ? sleRippleState->getFieldU32(sfFlags) : 0u;
        // Computing expected trust line state
        uFlags = computeFreezeFlags(
            uFlags,
            bHigh,
            bNoFreeze,
            bSetFreeze,
            bClearFreeze,
            bSetDeepFreeze,
            bClearDeepFreeze);
 
        auto const frozen = uFlags & (bHigh ? lsfHighFreeze : lsfLowFreeze);
        auto const deepFrozen =
            uFlags & (bHigh ? lsfHighDeepFreeze : lsfLowDeepFreeze);
 
        // Trying to set deep freeze on not already frozen trust line must
        // fail. This also checks that clearing normal freeze while deep
        // frozen must not work
        if (deepFrozen && !frozen)
        {
            return tecNO_PERMISSION;
        }
    }
 
    return tesSUCCESS;
}
 
TER
SetTrust::doApply()
{
    TER terResult = tesSUCCESS;
 
    STAmount const saLimitAmount(ctx_.tx.getFieldAmount(sfLimitAmount));
    bool const bQualityIn(ctx_.tx.isFieldPresent(sfQualityIn));
    bool const bQualityOut(ctx_.tx.isFieldPresent(sfQualityOut));
 
    Currency const currency(saLimitAmount.getCurrency());
    AccountID uDstAccountID(saLimitAmount.getIssuer());
 
    // true, if current is high account.
    bool const bHigh = account_ > uDstAccountID;
 
    auto const sle = view().peek(keylet::account(account_));
    if (!sle)
        return tefINTERNAL;  // LCOV_EXCL_LINE
 
    std::uint32_t const uOwnerCount = sle->getFieldU32(sfOwnerCount);
 
    // The reserve that is required to create the line. Note
    // that although the reserve increases with every item
    // an account owns, in the case of trust lines we only
    // *enforce* a reserve if the user owns more than two
    // items.
    //
    // We do this because being able to exchange currencies,
    // which needs trust lines, is a powerful Ripple feature.
    // So we want to make it easy for a gateway to fund the
    // accounts of its users without fear of being tricked.
    //
    // Without this logic, a gateway that wanted to have a
    // new user use its services, would have to give that
    // user enough XRP to cover not only the account reserve
    // but the incremental reserve for the trust line as
    // well. A person with no intention of using the gateway
    // could use the extra XRP for their own purposes.
 
    XRPAmount const reserveCreate(
        (uOwnerCount < 2) ? XRPAmount(beast::zero)
                          : view().fees().accountReserve(uOwnerCount + 1));
 
    std::uint32_t uQualityIn(bQualityIn ? ctx_.tx.getFieldU32(sfQualityIn) : 0);
    std::uint32_t uQualityOut(
        bQualityOut ? ctx_.tx.getFieldU32(sfQualityOut) : 0);
 
    if (bQualityOut && QUALITY_ONE == uQualityOut)
        uQualityOut = 0;
 
    std::uint32_t const uTxFlags = ctx_.tx.getFlags();
 
    bool const bSetAuth = (uTxFlags & tfSetfAuth);
    bool const bSetNoRipple = (uTxFlags & tfSetNoRipple);
    bool const bClearNoRipple = (uTxFlags & tfClearNoRipple);
    bool const bSetFreeze = (uTxFlags & tfSetFreeze);
    bool const bClearFreeze = (uTxFlags & tfClearFreeze);
    bool const bSetDeepFreeze = (uTxFlags & tfSetDeepFreeze);
    bool const bClearDeepFreeze = (uTxFlags & tfClearDeepFreeze);
 
    auto viewJ = ctx_.app.journal("View");
 
    SLE::pointer sleDst = view().peek(keylet::account(uDstAccountID));
 
    if (!sleDst)
    {
        JLOG(j_.trace())
            << "Delay transaction: Destination account does not exist.";
        return tecNO_DST;
    }
 
    STAmount saLimitAllow = saLimitAmount;
    saLimitAllow.setIssuer(account_);
 
    SLE::pointer sleRippleState =
        view().peek(keylet::line(account_, uDstAccountID, currency));
 
    if (sleRippleState)
    {
        STAmount saLowBalance;
        STAmount saLowLimit;
        STAmount saHighBalance;
        STAmount saHighLimit;
        std::uint32_t uLowQualityIn;
        std::uint32_t uLowQualityOut;
        std::uint32_t uHighQualityIn;
        std::uint32_t uHighQualityOut;
        auto const& uLowAccountID = !bHigh ? account_ : uDstAccountID;
        auto const& uHighAccountID = bHigh ? account_ : uDstAccountID;
        SLE::ref sleLowAccount = !bHigh ? sle : sleDst;
        SLE::ref sleHighAccount = bHigh ? sle : sleDst;
 
        //
        // Balances
        //
 
        saLowBalance = sleRippleState->getFieldAmount(sfBalance);
        saHighBalance = -saLowBalance;
 
        //
        // Limits
        //
 
        sleRippleState->setFieldAmount(
            !bHigh ? sfLowLimit : sfHighLimit, saLimitAllow);
 
        saLowLimit =
            !bHigh ? saLimitAllow : sleRippleState->getFieldAmount(sfLowLimit);
        saHighLimit =
            bHigh ? saLimitAllow : sleRippleState->getFieldAmount(sfHighLimit);
 
        //
        // Quality in
        //
 
        if (!bQualityIn)
        {
            // Not setting. Just get it.
 
            uLowQualityIn = sleRippleState->getFieldU32(sfLowQualityIn);
            uHighQualityIn = sleRippleState->getFieldU32(sfHighQualityIn);
        }
        else if (uQualityIn)
        {
            // Setting.
 
            sleRippleState->setFieldU32(
                !bHigh ? sfLowQualityIn : sfHighQualityIn, uQualityIn);
 
            uLowQualityIn = !bHigh
                ? uQualityIn
                : sleRippleState->getFieldU32(sfLowQualityIn);
            uHighQualityIn = bHigh
                ? uQualityIn
                : sleRippleState->getFieldU32(sfHighQualityIn);
        }
        else
        {
            // Clearing.
 
            sleRippleState->makeFieldAbsent(
                !bHigh ? sfLowQualityIn : sfHighQualityIn);
 
            uLowQualityIn =
                !bHigh ? 0 : sleRippleState->getFieldU32(sfLowQualityIn);
            uHighQualityIn =
                bHigh ? 0 : sleRippleState->getFieldU32(sfHighQualityIn);
        }
 
        if (QUALITY_ONE == uLowQualityIn)
            uLowQualityIn = 0;
 
        if (QUALITY_ONE == uHighQualityIn)
            uHighQualityIn = 0;
 
        //
        // Quality out
        //
 
        if (!bQualityOut)
        {
            // Not setting. Just get it.
 
            uLowQualityOut = sleRippleState->getFieldU32(sfLowQualityOut);
            uHighQualityOut = sleRippleState->getFieldU32(sfHighQualityOut);
        }
        else if (uQualityOut)
        {
            // Setting.
 
            sleRippleState->setFieldU32(
                !bHigh ? sfLowQualityOut : sfHighQualityOut, uQualityOut);
 
            uLowQualityOut = !bHigh
                ? uQualityOut
                : sleRippleState->getFieldU32(sfLowQualityOut);
            uHighQualityOut = bHigh
                ? uQualityOut
                : sleRippleState->getFieldU32(sfHighQualityOut);
        }
        else
        {
            // Clearing.
 
            sleRippleState->makeFieldAbsent(
                !bHigh ? sfLowQualityOut : sfHighQualityOut);
 
            uLowQualityOut =
                !bHigh ? 0 : sleRippleState->getFieldU32(sfLowQualityOut);
            uHighQualityOut =
                bHigh ? 0 : sleRippleState->getFieldU32(sfHighQualityOut);
        }
 
        std::uint32_t const uFlagsIn(sleRippleState->getFieldU32(sfFlags));
        std::uint32_t uFlagsOut(uFlagsIn);
 
        if (bSetNoRipple && !bClearNoRipple)
        {
            if ((bHigh ? saHighBalance : saLowBalance) >= beast::zero)
                uFlagsOut |= (bHigh ? lsfHighNoRipple : lsfLowNoRipple);
 
            else
                // Cannot set noRipple on a negative balance.
                return tecNO_PERMISSION;
        }
        else if (bClearNoRipple && !bSetNoRipple)
        {
            uFlagsOut &= ~(bHigh ? lsfHighNoRipple : lsfLowNoRipple);
        }
 
        // Have to use lsfNoFreeze to maintain pre-deep freeze behavior
        bool const bNoFreeze = sle->isFlag(lsfNoFreeze);
        uFlagsOut = computeFreezeFlags(
            uFlagsOut,
            bHigh,
            bNoFreeze,
            bSetFreeze,
            bClearFreeze,
            bSetDeepFreeze,
            bClearDeepFreeze);
 
        if (QUALITY_ONE == uLowQualityOut)
            uLowQualityOut = 0;
 
        if (QUALITY_ONE == uHighQualityOut)
            uHighQualityOut = 0;
 
        bool const bLowDefRipple = sleLowAccount->getFlags() & lsfDefaultRipple;
        bool const bHighDefRipple =
            sleHighAccount->getFlags() & lsfDefaultRipple;
 
        bool const bLowReserveSet = uLowQualityIn || uLowQualityOut ||
            ((uFlagsOut & lsfLowNoRipple) == 0) != bLowDefRipple ||
            (uFlagsOut & lsfLowFreeze) || saLowLimit ||
            saLowBalance > beast::zero;
        bool const bLowReserveClear = !bLowReserveSet;
 
        bool const bHighReserveSet = uHighQualityIn || uHighQualityOut ||
            ((uFlagsOut & lsfHighNoRipple) == 0) != bHighDefRipple ||
            (uFlagsOut & lsfHighFreeze) || saHighLimit ||
            saHighBalance > beast::zero;
        bool const bHighReserveClear = !bHighReserveSet;
 
        bool const bDefault = bLowReserveClear && bHighReserveClear;
 
        bool const bLowReserved = (uFlagsIn & lsfLowReserve);
        bool const bHighReserved = (uFlagsIn & lsfHighReserve);
 
        bool bReserveIncrease = false;
 
        if (bSetAuth)
        {
            uFlagsOut |= (bHigh ? lsfHighAuth : lsfLowAuth);
        }
 
        if (bLowReserveSet && !bLowReserved)
        {
            // Set reserve for low account.
            adjustOwnerCount(view(), sleLowAccount, 1, viewJ);
            uFlagsOut |= lsfLowReserve;
 
            if (!bHigh)
                bReserveIncrease = true;
        }
 
        if (bLowReserveClear && bLowReserved)
        {
            // Clear reserve for low account.
            adjustOwnerCount(view(), sleLowAccount, -1, viewJ);
            uFlagsOut &= ~lsfLowReserve;
        }
 
        if (bHighReserveSet && !bHighReserved)
        {
            // Set reserve for high account.
            adjustOwnerCount(view(), sleHighAccount, 1, viewJ);
            uFlagsOut |= lsfHighReserve;
 
            if (bHigh)
                bReserveIncrease = true;
        }
 
        if (bHighReserveClear && bHighReserved)
        {
            // Clear reserve for high account.
            adjustOwnerCount(view(), sleHighAccount, -1, viewJ);
            uFlagsOut &= ~lsfHighReserve;
        }
 
        if (uFlagsIn != uFlagsOut)
            sleRippleState->setFieldU32(sfFlags, uFlagsOut);
 
        if (bDefault || badCurrency() == currency)
        {
            // Delete.
 
            terResult = trustDelete(
                view(), sleRippleState, uLowAccountID, uHighAccountID, viewJ);
        }
        // Reserve is not scaled by load.
        else if (bReserveIncrease && mPriorBalance < reserveCreate)
        {
            JLOG(j_.trace()) << "Delay transaction: Insufficent reserve to "
                                "add trust line.";
 
            // Another transaction could provide XRP to the account and then
            // this transaction would succeed.
            terResult = tecINSUF_RESERVE_LINE;
        }
        else
        {
            view().update(sleRippleState);
 
            JLOG(j_.trace()) << "Modify ripple line";
        }
    }
    // Line does not exist.
    else if (
        !saLimitAmount &&                  // Setting default limit.
        (!bQualityIn || !uQualityIn) &&    // Not setting quality in or
                                           // setting default quality in.
        (!bQualityOut || !uQualityOut) &&  // Not setting quality out or
                                           // setting default quality out.
        (!bSetAuth))
    {
        JLOG(j_.trace())
            << "Redundant: Setting non-existent ripple line to defaults.";
        return tecNO_LINE_REDUNDANT;
    }
    else if (mPriorBalance < reserveCreate)  // Reserve is not scaled by
                                             // load.
    {
        JLOG(j_.trace()) << "Delay transaction: Line does not exist. "
                            "Insufficent reserve to create line.";
 
        // Another transaction could create the account and then this
        // transaction would succeed.
        terResult = tecNO_LINE_INSUF_RESERVE;
    }
    else
    {
        // Zero balance in currency.
        STAmount saBalance(Issue{currency, noAccount()});
 
        auto const k = keylet::line(account_, uDstAccountID, currency);
 
        JLOG(j_.trace()) << "doTrustSet: Creating ripple line: "
                         << to_string(k.key);
 
        // Create a new ripple line.
        terResult = trustCreate(
            view(),
            bHigh,
            account_,
            uDstAccountID,
            k.key,
            sle,
            bSetAuth,
            bSetNoRipple && !bClearNoRipple,
            bSetFreeze && !bClearFreeze,
            bSetDeepFreeze,
            saBalance,
            saLimitAllow,  // Limit for who is being charged.
            uQualityIn,
            uQualityOut,
            viewJ);
    }
 
    return terResult;
}
 
}  // namespace xrpl