View.cpp

#include <xrpl/ledger/View.h>
 
#include <xrpl/basics/Log.h>
#include <xrpl/basics/base_uint.h>
#include <xrpl/basics/chrono.h>
#include <xrpl/basics/safe_cast.h>
#include <xrpl/beast/utility/Journal.h>
#include <xrpl/beast/utility/Zero.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/ledger/ApplyView.h>
#include <xrpl/ledger/ReadView.h>
#include <xrpl/ledger/entries/AmendmentsEntry.h>
#include <xrpl/ledger/entries/LedgerHashesEntry.h>
#include <xrpl/ledger/helpers/AccountRootHelpers.h>
#include <xrpl/ledger/helpers/CredentialHelpers.h>
#include <xrpl/ledger/helpers/DirectoryHelpers.h>
#include <xrpl/ledger/helpers/MPTokenHelpers.h>
#include <xrpl/ledger/helpers/RippleStateHelpers.h>
#include <xrpl/ledger/helpers/SponsorHelpers.h>
#include <xrpl/ledger/helpers/TokenHelpers.h>
#include <xrpl/protocol/AccountID.h>
#include <xrpl/protocol/Asset.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/Issue.h>
#include <xrpl/protocol/Keylet.h>
#include <xrpl/protocol/LedgerFormats.h>
#include <xrpl/protocol/MPTIssue.h>
#include <xrpl/protocol/Protocol.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STAmount.h>
#include <xrpl/protocol/STLedgerEntry.h>
#include <xrpl/protocol/STTx.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/XRPAmount.h>
 
#include <cstdint>
#include <optional>
#include <set>
#include <vector>
 
namespace xrpl {
 
//------------------------------------------------------------------------------
//
// Observers
//
//------------------------------------------------------------------------------
 
bool
hasExpired(
    ReadView const& view,
    std::optional<std::uint32_t> const& exp,
    ExpiryComparison comparison)
{
    using D = NetClock::duration;
    using Tp = NetClock::time_point;
 
    if (!exp)
        return false;
    auto const boundary = Tp{D{*exp}};
    return comparison == ExpiryComparison::Inclusive  //
        ? view.parentCloseTime() >= boundary
        : view.parentCloseTime() > boundary;
}
 
namespace {
 
std::optional<bool>
checkVaultPseudoAccountFrozenPreconditions(ReadView const& view, std::uint8_t depth)
{
    if (!view.rules().enabled(featureSingleAssetVault))
        return false;
 
    if (depth >= kMaxAssetCheckDepth)
    {
        // LCOV_EXCL_START
        UNREACHABLE(
            "xrpl::View::checkVaultPseudoAccountFrozenPreconditions : reached asset check depth");
        return true;
        // LCOV_EXCL_STOP
    }
 
    return std::nullopt;
}
 
bool
isVaultPseudoAccountFrozenForIssuance(
    ReadView const& view,
    AccountID const& account,
    SLE const& issuanceSle,
    std::uint8_t depth)
{
    XRPL_ASSERT(
        issuanceSle.getType() == ltMPTOKEN_ISSUANCE,
        "xrpl::isVaultPseudoAccountFrozenForIssuance : MPTokenIssuance SLE");
 
    auto const issuer = issuanceSle.getAccountID(sfIssuer);
 
    // Post-fixCleanup3_2_0: vault shares carry sfReferenceHolding pointing
    // to the vault pseudo's MPToken or RippleState for the underlying.
    // Read it to derive the underlying asset and recurse, skipping the
    // issuer-account-then-vault chain. Pre-amendment shares (no field)
    // fall back to the chain lookup below.
    if (issuanceSle.isFieldPresent(sfReferenceHolding))
    {
        auto const sleHolding =
            view.read(keylet::unchecked(issuanceSle.getFieldH256(sfReferenceHolding)));
        if (!sleHolding)
        {
            // LCOV_EXCL_START
            UNREACHABLE("xrpl::isVaultPseudoAccountFrozen : dangling sfReferenceHolding");
            return false;
            // LCOV_EXCL_STOP
        }
        return isAnyFrozen(
            view, {issuer, account}, assetOfHolding(issuanceSle, *sleHolding), depth + 1);
    }
 
    auto const mptIssuer = view.read(keylet::account(issuer));
    if (mptIssuer == nullptr)
    {
        // LCOV_EXCL_START
        UNREACHABLE("xrpl::isVaultPseudoAccountFrozen : null MPToken issuer");
        return false;
        // LCOV_EXCL_STOP
    }
 
    if (!mptIssuer->isFieldPresent(sfVaultID))
        return false;  // not a Vault pseudo-account, common case
 
    auto const vault = view.read(keylet::vault(mptIssuer->getFieldH256(sfVaultID)));
    if (vault == nullptr)
    {  // LCOV_EXCL_START
        UNREACHABLE("xrpl::isVaultPseudoAccountFrozen : null vault");
        return false;
        // LCOV_EXCL_STOP
    }
 
    return isAnyFrozen(view, {issuer, account}, vault->at(sfAsset), depth + 1);
}
 
}  // namespace
 
bool
isVaultPseudoAccountFrozen(
    ReadView const& view,
    AccountID const& account,
    SLE const& issuanceSle,
    std::uint8_t depth)
{
    if (auto const result = checkVaultPseudoAccountFrozenPreconditions(view, depth))
        return *result;
 
    return isVaultPseudoAccountFrozenForIssuance(view, account, issuanceSle, depth);
}
 
bool
isVaultPseudoAccountFrozen(
    ReadView const& view,
    AccountID const& account,
    MPTIssue const& mptShare,
    std::uint8_t depth)
{
    if (auto const result = checkVaultPseudoAccountFrozenPreconditions(view, depth))
        return *result;
 
    auto const issuanceSle = view.read(keylet::mptokenIssuance(mptShare.getMptID()));
    if (issuanceSle == nullptr)
        return false;  // zero MPToken won't block deletion of MPTokenIssuance
 
    return isVaultPseudoAccountFrozenForIssuance(view, account, *issuanceSle, depth);
}
 
bool
isLPTokenFrozen(
    ReadView const& view,
    AccountID const& account,
    Asset const& asset,
    Asset const& asset2)
{
    return isFrozen(view, account, asset) || isFrozen(view, account, asset2);
}
 
TER
canTransferLPToken(
    ReadView const& view,
    AccountID const& from,
    AccountID const& to,
    AccountID const& lpTokenIssuer)
{
    // Only AMM-issued LPTokens are subject to this check. The LPToken's issuer
    // is the AMM account; if it is not an AMM, this is not an LPToken.
    auto const sleIssuer = view.read(keylet::account(lpTokenIssuer));
    if (!sleIssuer || !sleIssuer->isFieldPresent(sfAMMID))
        return tesSUCCESS;
 
    auto const sleAmm = view.read(keylet::amm((*sleIssuer)[sfAMMID]));
    if (!sleAmm)
        return tecINTERNAL;  // LCOV_EXCL_LINE
 
    auto const transferable = [&](Asset const& a) -> TER {
        if (!a.holds<MPTIssue>())
            return tesSUCCESS;
        return canTransfer(view, a.get<MPTIssue>(), from, to);
    };
    if (auto const err = transferable((*sleAmm)[sfAsset]); !isTesSuccess(err))
        return err;
    return transferable((*sleAmm)[sfAsset2]);
}
 
bool
areCompatible(
    ReadView const& validLedger,
    ReadView const& testLedger,
    beast::Journal::Stream& s,
    char const* reason)
{
    bool ret = true;
 
    if (validLedger.header().seq < testLedger.header().seq)
    {
        // valid -> ... -> test
        auto hash = hashOfSeq(
            testLedger, validLedger.header().seq, beast::Journal{beast::Journal::getNullSink()});
        if (hash && (*hash != validLedger.header().hash))
        {
            JLOG(s) << reason << " incompatible with valid ledger";
 
            JLOG(s) << "Hash(VSeq): " << to_string(*hash);
 
            ret = false;
        }
    }
    else if (validLedger.header().seq > testLedger.header().seq)
    {
        // test -> ... -> valid
        auto hash = hashOfSeq(
            validLedger, testLedger.header().seq, beast::Journal{beast::Journal::getNullSink()});
        if (hash && (*hash != testLedger.header().hash))
        {
            JLOG(s) << reason << " incompatible preceding ledger";
 
            JLOG(s) << "Hash(NSeq): " << to_string(*hash);
 
            ret = false;
        }
    }
    else if (
        (validLedger.header().seq == testLedger.header().seq) &&
        (validLedger.header().hash != testLedger.header().hash))
    {
        // Same sequence number, different hash
        JLOG(s) << reason << " incompatible ledger";
 
        ret = false;
    }
 
    if (!ret)
    {
        JLOG(s) << "Val: " << validLedger.header().seq << " "
                << to_string(validLedger.header().hash);
 
        JLOG(s) << "New: " << testLedger.header().seq << " " << to_string(testLedger.header().hash);
    }
 
    return ret;
}
 
bool
areCompatible(
    UInt256 const& validHash,
    LedgerIndex validIndex,
    ReadView const& testLedger,
    beast::Journal::Stream& s,
    char const* reason)
{
    bool ret = true;
 
    if (testLedger.header().seq > validIndex)
    {
        // Ledger we are testing follows last valid ledger
        auto hash =
            hashOfSeq(testLedger, validIndex, beast::Journal{beast::Journal::getNullSink()});
        if (hash && (*hash != validHash))
        {
            JLOG(s) << reason << " incompatible following ledger";
            JLOG(s) << "Hash(VSeq): " << to_string(*hash);
 
            ret = false;
        }
    }
    else if ((validIndex == testLedger.header().seq) && (testLedger.header().hash != validHash))
    {
        JLOG(s) << reason << " incompatible ledger";
 
        ret = false;
    }
 
    if (!ret)
    {
        JLOG(s) << "Val: " << validIndex << " " << to_string(validHash);
 
        JLOG(s) << "New: " << testLedger.header().seq << " " << to_string(testLedger.header().hash);
    }
 
    return ret;
}
 
std::set<UInt256>
getEnabledAmendments(ReadView const& view)
{
    return AmendmentsEntryR(view).enabledAmendments();
}
 
MajorityAmendmentsT
getMajorityAmendments(ReadView const& view)
{
    return AmendmentsEntryR(view).majorityAmendments();
}
 
std::optional<UInt256>
hashOfSeq(ReadView const& ledger, LedgerIndex seq, beast::Journal journal)
{
    // Easy cases...
    if (seq > ledger.seq())
    {
        JLOG(journal.warn()) << "Can't get seq " << seq << " from " << ledger.seq() << " future";
        return std::nullopt;
    }
    if (seq == ledger.seq())
        return ledger.header().hash;
    if (seq == (ledger.seq() - 1))
        return ledger.header().parentHash;
 
    if (int const diff = ledger.seq() - seq; diff <= 256)
    {
        // Within 256...
        LedgerHashesEntryR const hashIndex(ledger, journal);
        if (hashIndex)
        {
            XRPL_ASSERT(
                hashIndex->getFieldU32(sfLastLedgerSequence) == (ledger.seq() - 1),
                "xrpl::hashOfSeq : matching ledger sequence");
            if (auto const hash = hashIndex.hashAt(diff - 1))
                return hash;
            JLOG(journal.warn()) << "Ledger " << ledger.seq() << " missing hash for " << seq << " ("
                                 << hashIndex->getFieldV256(sfHashes).size() << "," << diff << ")";
        }
        else
        {
            JLOG(journal.warn()) << "Ledger " << ledger.seq() << ":" << ledger.header().hash
                                 << " missing normal list";
        }
    }
 
    if ((seq & 0xff) != 0)
    {
        JLOG(journal.debug()) << "Can't get seq " << seq << " from " << ledger.seq() << " past";
        return std::nullopt;
    }
 
    // in skiplist
    LedgerHashesEntryR const hashIndex(keylet::skip(seq), ledger, journal);
    if (hashIndex)
    {
        auto const lastSeq = hashIndex->getFieldU32(sfLastLedgerSequence);
        XRPL_ASSERT(lastSeq >= seq, "xrpl::hashOfSeq : minimum last ledger");
        XRPL_ASSERT((lastSeq & 0xff) == 0, "xrpl::hashOfSeq : valid last ledger");
        if (auto const hash = hashIndex.hashAt((lastSeq - seq) >> 8))
            return hash;
    }
    JLOG(journal.warn()) << "Can't get seq " << seq << " from " << ledger.seq() << " error";
    return std::nullopt;
}
 
//------------------------------------------------------------------------------
//
// Modifiers
//
//------------------------------------------------------------------------------
 
TER
dirLink(ApplyView& view, AccountID const& owner, SLE::pointer& object, SF_UINT64 const& node)
{
    auto const page =
        view.dirInsert(keylet::ownerDir(owner), object->key(), describeOwnerDir(owner));
    if (!page)
        return tecDIR_FULL;  // LCOV_EXCL_LINE
    object->setFieldU64(node, *page);
    return tesSUCCESS;
}
 
/*
 * Checks if a withdrawal amount into the destination account exceeds
 * any applicable receiving limit.
 * Called by VaultWithdraw and LoanBrokerCoverWithdraw.
 *
 * IOU : Performs the trustline check against the destination account's
 * credit limit to ensure the account's trust maximum is not exceeded.
 *
 * MPT: The limit check is effectively skipped (returns true). This is
 * because MPT MaximumAmount relates to token supply, and withdrawal does not
 * involve minting new tokens that could exceed the global cap.
 * On withdrawal, tokens are simply transferred from the vault's pseudo-account
 * to the destination account. Since no new MPT tokens are minted during this
 * transfer, the withdrawal cannot violate the MPT MaximumAmount/supply cap
 * even if `from` is the issuer.
 */
static TER
withdrawToDestExceedsLimit(
    ReadView const& view,
    AccountID const& from,
    AccountID const& to,
    STAmount const& amount)
{
    auto const& issuer = amount.getIssuer();
    if (from == to || to == issuer || isXRP(issuer))
        return tesSUCCESS;
 
    return amount.asset().visit(
        [&](Issue const& issue) -> TER {
            auto const& currency = issue.currency;
            auto const owed = creditBalance(view, to, issuer, currency);
            if (owed <= beast::kZero)
            {
                auto const limit = creditLimit(view, to, issuer, currency);
                if (-owed >= limit || amount > (limit + owed))
                    return tecNO_LINE;
            }
            return tesSUCCESS;
        },
        [](MPTIssue const&) -> TER { return tesSUCCESS; });
}
 
[[nodiscard]] TER
canWithdraw(
    ReadView const& view,
    AccountID const& from,
    AccountID const& to,
    SLE::ConstRef toSle,
    STAmount const& amount,
    bool hasDestinationTag,
    std::optional<std::vector<UInt256>> const& credentialIDs)
{
    if (auto const ret = checkDestinationAndTag(toSle, hasDestinationTag))
        return ret;
 
    if (from == to)
        return tesSUCCESS;
 
    if (toSle->isFlag(lsfDepositAuth))
    {
        if (!view.exists(keylet::depositPreauth(to, from)))
        {
            if (credentialIDs.has_value())
            {
                STVector256 const credIDs{*credentialIDs};
 
                // Callers must have validated these in preclaim, so a missing
                // credential here is an invariant violation.
                for (auto const& h : credIDs)
                {
                    if (!view.exists(keylet::credential(h)))
                        return tecINTERNAL;  // LCOV_EXCL_LINE
                }
 
                if (auto const ret = credentials::authorizedDepositPreauth(view, credIDs, to);
                    !isTesSuccess(ret))
                    return ret;
            }
            else
            {
                return tecNO_PERMISSION;
            }
        }
    }
 
    return withdrawToDestExceedsLimit(view, from, to, amount);
}
 
[[nodiscard]] TER
canWithdraw(
    ReadView const& view,
    AccountID const& from,
    AccountID const& to,
    STAmount const& amount,
    bool hasDestinationTag,
    std::optional<std::vector<UInt256>> const& credentialIDs)
{
    auto const toSle = view.read(keylet::account(to));
 
    return canWithdraw(view, from, to, toSle, amount, hasDestinationTag, credentialIDs);
}
 
[[nodiscard]] TER
canWithdraw(ReadView const& view, STTx const& tx)
{
    auto const from = tx[sfAccount];
    auto const to = tx[~sfDestination].value_or(from);
 
    return canWithdraw(
        view, from, to, tx[sfAmount], tx.isFieldPresent(sfDestinationTag), tx[~sfCredentialIDs]);
}
 
TER
doWithdraw(
    ApplyViewContext ctx,
    AccountID const& senderAcct,
    AccountID const& dstAcct,
    AccountID const& sourceAcct,
    XRPAmount priorBalance,
    STAmount const& amount,
    beast::Journal j)
{
    auto const dstSle = ctx.view.read(keylet::account(dstAcct));
 
    // Create a trust line or MPToken for a self-destination only when there
    // is a payout to credit. Post-fixCleanup3_4_0, a zero-value withdraw
    // (e.g. share redemption from a fully impaired vault) must not insert
    // an empty holding: that records a one-sided zero delta and can also
    // create+delete MPTokens in the same transaction.
    if (dstAcct == senderAcct)
    {
        if (amount > beast::kZero || !ctx.view.rules().enabled(fixCleanup3_4_0))
        {
            if (auto const ter = addEmptyHolding(ctx, senderAcct, priorBalance, amount.asset(), j);
                !isTesSuccess(ter) && ter != tecDUPLICATE)
                return ter;
        }
    }
    else
    {
        if (auto err = verifyDepositPreauth(ctx.tx, ctx.view, senderAcct, dstAcct, dstSle, j))
            return err;
    }
 
    // Sanity check
    if (accountHolds(
            ctx.view,
            sourceAcct,
            amount.asset(),
            FreezeHandling::IgnoreFreeze,
            AuthHandling::IgnoreAuth,
            j) < amount)
    {
        // LCOV_EXCL_START
        JLOG(j.error()) << "doWithdraw: negative balance of broker cover assets.";
        return tefINTERNAL;
        // LCOV_EXCL_STOP
    }
 
    // A reserve sponsor only covers tx.Account's own objects, so resolve the
    // sponsor against the destination. accountSend can auto-create a holding
    // for dstAcct; keying on the destination ensures a third-party destination's
    // holding is never stamped with the tx's reserve sponsor.
    auto const sponsorSle = getEffectiveTxReserveSponsor(ctx, dstSle);
    if (!sponsorSle)
        return sponsorSle.error();  // LCOV_EXCL_LINE
 
    // Move the funds directly from the broker's pseudo-account to the
    // dstAcct
    return accountSend(
        ctx.view, sourceAcct, dstAcct, amount, j, *sponsorSle, WaiveTransferFee::Yes);
}
 
TER
cleanupOnAccountDelete(
    ApplyView& view,
    Keylet const& ownerDirKeylet,
    EntryDeleter const& deleter,
    beast::Journal j,
    std::optional<uint16_t> maxNodesToDelete)
{
    // Delete all the entries in the account directory.
    SLE::pointer sleDirNode{};
    unsigned int uDirEntry{0};
    UInt256 dirEntry{beast::kZero};
    std::uint32_t deleted = 0;
 
    if (view.exists(ownerDirKeylet) &&
        dirFirst(view, ownerDirKeylet.key, sleDirNode, uDirEntry, dirEntry))
    {
        do
        {
            if (maxNodesToDelete && ++deleted > *maxNodesToDelete)
                return tecINCOMPLETE;
 
            // Choose the right way to delete each directory node.
            auto sleItem = view.peek(keylet::child(dirEntry));
            if (!sleItem)
            {
                // Directory node has an invalid index.  Bail out.
                // LCOV_EXCL_START
                JLOG(j.fatal()) << "DeleteAccount: Directory node in ledger " << view.seq()
                                << " has index to object that is missing: " << to_string(dirEntry);
                return tefBAD_LEDGER;
                // LCOV_EXCL_STOP
            }
 
            LedgerEntryType const nodeType{
                safeCast<LedgerEntryType>(sleItem->getFieldU16(sfLedgerEntryType))};
 
            // Deleter handles the details of specific account-owned object
            // deletion
            auto const [ter, skipEntry] = deleter(nodeType, dirEntry, sleItem);
            if (!isTesSuccess(ter))
                return ter;
 
            // dirFirst() and dirNext() are like iterators with exposed
            // internal state.  We'll take advantage of that exposed state
            // to solve a common C++ problem: iterator invalidation while
            // deleting elements from a container.
            //
            // We have just deleted one directory entry, which means our
            // "iterator state" is invalid.
            //
            //  1. During the process of getting an entry from the
            //     directory uDirEntry was incremented from 'it' to 'it'+1.
            //
            //  2. We then deleted the entry at index 'it', which means the
            //     entry that was at 'it'+1 has now moved to 'it'.
            //
            //  3. So we verify that uDirEntry is indeed 'it'+1.  Then we jam it
            //     back to 'it' to "un-invalidate" the iterator.
            XRPL_ASSERT(uDirEntry >= 1, "xrpl::cleanupOnAccountDelete : minimum dir entries");
            if (uDirEntry == 0)
            {
                // LCOV_EXCL_START
                JLOG(j.error()) << "DeleteAccount iterator re-validation failed.";
                return tefBAD_LEDGER;
                // LCOV_EXCL_STOP
            }
            if (skipEntry == SkipEntry::No)
                uDirEntry--;
 
        } while (dirNext(view, ownerDirKeylet.key, sleDirNode, uDirEntry, dirEntry));
    }
 
    return tesSUCCESS;
}
 
bool
after(NetClock::time_point now, std::uint32_t mark)
{
    return now.time_since_epoch().count() > mark;
}
 
}  // namespace xrpl