AccountDelete.cpp

#include <xrpl/tx/transactors/account/AccountDelete.h>
 
#include <xrpl/basics/Log.h>
#include <xrpl/basics/base_uint.h>
#include <xrpl/basics/safe_cast.h>
#include <xrpl/beast/utility/Zero.h>
#include <xrpl/beast/utility/instrumentation.h>
#include <xrpl/core/ServiceRegistry.h>
#include <xrpl/ledger/ApplyView.h>
#include <xrpl/ledger/ReadView.h>
#include <xrpl/ledger/View.h>
#include <xrpl/ledger/helpers/CredentialHelpers.h>
#include <xrpl/ledger/helpers/DirectoryHelpers.h>
#include <xrpl/ledger/helpers/NFTokenHelpers.h>
#include <xrpl/ledger/helpers/OfferHelpers.h>
#include <xrpl/protocol/AccountID.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/Keylet.h>
#include <xrpl/protocol/LedgerFormats.h>
#include <xrpl/protocol/Protocol.h>
#include <xrpl/protocol/SField.h>
#include <xrpl/protocol/STLedgerEntry.h>
#include <xrpl/protocol/STTx.h>
#include <xrpl/protocol/TER.h>
#include <xrpl/protocol/XRPAmount.h>
#include <xrpl/tx/Transactor.h>
#include <xrpl/tx/transactors/account/SignerListSet.h>
#include <xrpl/tx/transactors/delegate/DelegateSet.h>
#include <xrpl/tx/transactors/did/DIDDelete.h>
#include <xrpl/tx/transactors/oracle/OracleDelete.h>
#include <xrpl/tx/transactors/payment/DepositPreauth.h>
 
#include <cstdint>
#include <utility>
 
namespace xrpl {
bool
AccountDelete::checkExtraFeatures(PreflightContext const& ctx)
{
    return !ctx.tx.isFieldPresent(sfCredentialIDs) || ctx.rules.enabled(featureCredentials);
}
 
NotTEC
AccountDelete::preflight(PreflightContext const& ctx)
{
    if (ctx.tx[sfAccount] == ctx.tx[sfDestination])
    {
        // An account cannot be deleted and give itself the resulting XRP.
        return temDST_IS_SRC;
    }
 
    if (auto const err = credentials::checkFields(ctx.tx, ctx.rules, ctx.j); !isTesSuccess(err))
        return err;
 
    return tesSUCCESS;
}
 
XRPAmount
AccountDelete::calculateBaseFee(ReadView const& view, STTx const& tx)
{
    // The fee required for AccountDelete is one owner reserve.
    return calculateOwnerReserveFee(view, tx);
}
 
namespace {
// Define a function pointer type that can be used to delete ledger node types.
using DeleterFuncPtr = TER (*)(
    ServiceRegistry& registry,
    ApplyView& view,
    AccountID const& account,
    uint256 const& delIndex,
    SLE::ref sleDel,
    beast::Journal j);
 
// Local function definitions that provides signature compatibility.
TER
offerDelete(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const& account,
    uint256 const& delIndex,
    SLE::ref sleDel,
    beast::Journal j)
{
    return offerDelete(view, sleDel, j);
}
 
TER
removeSignersFromLedger(
    ServiceRegistry& registry,
    ApplyView& view,
    AccountID const& account,
    uint256 const& delIndex,
    SLE::ref sleDel,
    beast::Journal j)
{
    return SignerListSet::removeFromLedger(registry, view, account, j);
}
 
TER
removeTicketFromLedger(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const& account,
    uint256 const& delIndex,
    SLE::ref,
    beast::Journal j)
{
    return Transactor::ticketDelete(view, account, delIndex, j);
}
 
TER
removeDepositPreauthFromLedger(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const&,
    uint256 const& delIndex,
    SLE::ref,
    beast::Journal j)
{
    return DepositPreauth::removeFromLedger(view, delIndex, j);
}
 
TER
removeNFTokenOfferFromLedger(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const& account,
    uint256 const& delIndex,
    SLE::ref sleDel,
    beast::Journal)
{
    if (!nft::deleteTokenOffer(view, sleDel))
        return tefBAD_LEDGER;  // LCOV_EXCL_LINE
 
    return tesSUCCESS;
}
 
TER
removeDIDFromLedger(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const& account,
    uint256 const& delIndex,
    SLE::ref sleDel,
    beast::Journal j)
{
    return DIDDelete::deleteSLE(view, sleDel, account, j);
}
 
TER
removeOracleFromLedger(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const& account,
    uint256 const&,
    SLE::ref sleDel,
    beast::Journal j)
{
    return OracleDelete::deleteOracle(view, sleDel, account, j);
}
 
TER
removeCredentialFromLedger(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const&,
    uint256 const&,
    SLE::ref sleDel,
    beast::Journal j)
{
    return credentials::deleteSLE(view, sleDel, j);
}
 
TER
removeDelegateFromLedger(
    ServiceRegistry&,
    ApplyView& view,
    AccountID const&,
    uint256 const&,
    SLE::ref sleDel,
    beast::Journal j)
{
    return DelegateSet::deleteDelegate(view, sleDel, j);
}
 
// Return nullptr if the LedgerEntryType represents an obligation that can't
// be deleted.  Otherwise return the pointer to the function that can delete
// the non-obligation
DeleterFuncPtr
nonObligationDeleter(LedgerEntryType t)
{
    switch (t)
    {
        case ltOFFER:
            return offerDelete;
        case ltSIGNER_LIST:
            return removeSignersFromLedger;
        case ltTICKET:
            return removeTicketFromLedger;
        case ltDEPOSIT_PREAUTH:
            return removeDepositPreauthFromLedger;
        case ltNFTOKEN_OFFER:
            return removeNFTokenOfferFromLedger;
        case ltDID:
            return removeDIDFromLedger;
        case ltORACLE:
            return removeOracleFromLedger;
        case ltCREDENTIAL:
            return removeCredentialFromLedger;
        case ltDELEGATE:
            return removeDelegateFromLedger;
        default:
            return nullptr;
    }
}
 
}  // namespace
 
TER
AccountDelete::preclaim(PreclaimContext const& ctx)
{
    AccountID const account{ctx.tx[sfAccount]};
    AccountID const dst{ctx.tx[sfDestination]};
 
    auto sleDst = ctx.view.read(keylet::account(dst));
 
    if (!sleDst)
        return tecNO_DST;
 
    if (sleDst->isFlag(lsfRequireDestTag) && !ctx.tx[~sfDestinationTag])
        return tecDST_TAG_NEEDED;
 
    // If credentials are provided - check them anyway
    if (auto const err = credentials::valid(ctx.tx, ctx.view, account, ctx.j); !isTesSuccess(err))
        return err;
 
    // if credentials then postpone auth check to doApply, to check for expired
    // credentials
    if (!ctx.tx.isFieldPresent(sfCredentialIDs))
    {
        // Check whether the destination account requires deposit authorization.
        // This also checks if destination is a pseudo-account, since pseudo-accounts have the
        // lsfDepositAuth flag set by default
        if (sleDst->isFlag(lsfDepositAuth))
        {
            if (!ctx.view.exists(keylet::depositPreauth(dst, account)))
                return tecNO_PERMISSION;
        }
    }
 
    auto sleAccount = ctx.view.read(keylet::account(account));
    XRPL_ASSERT(sleAccount, "xrpl::AccountDelete::preclaim : non-null account");
    if (!sleAccount)
        return terNO_ACCOUNT;
 
    // If an issuer has any issued NFTs resident in the ledger then it
    // cannot be deleted.
    if ((*sleAccount)[~sfMintedNFTokens] != (*sleAccount)[~sfBurnedNFTokens])
        return tecHAS_OBLIGATIONS;
 
    // If the account owns any NFTs it cannot be deleted.
    Keylet const first = keylet::nftokenPageMin(account);
    Keylet const last = keylet::nftokenPageMax(account);
 
    auto const cp = ctx.view.read(
        Keylet(ltNFTOKEN_PAGE, ctx.view.succ(first.key, last.key.next()).value_or(last.key)));
    if (cp)
        return tecHAS_OBLIGATIONS;
 
    if (sleAccount->isFieldPresent(sfSponsor))
    {
        if (dst != sleAccount->getAccountID(sfSponsor))
            return tecNO_SPONSOR_PERMISSION;
    }
    if (sleAccount->isFieldPresent(sfSponsoringOwnerCount) ||
        sleAccount->isFieldPresent(sfSponsoringAccountCount))
        return tecHAS_OBLIGATIONS;
 
    // We don't allow an account to be deleted if its sequence number
    // is within 256 of the current ledger.  This prevents replay of old
    // transactions if this account is resurrected after it is deleted.
    //
    // We look at the account's Sequence rather than the transaction's
    // Sequence in preparation for Tickets.
    static constexpr std::uint32_t kSeqDelta{255};
    if ((*sleAccount)[sfSequence] + kSeqDelta > ctx.view.seq())
        return tecTOO_SOON;
 
    // We don't allow an account to be deleted if
    // <FirstNFTokenSequence + MintedNFTokens> is within 256 of the
    // current ledger. This is to prevent having duplicate NFTokenIDs after
    // account re-creation.
    //
    // Without this restriction, duplicate NFTokenIDs can be reproduced when
    // authorized minting is involved. Because when the minter mints a NFToken,
    // the issuer's sequence does not change. So when the issuer re-creates
    // their account and mints a NFToken, it is possible that the
    // NFTokenSequence of this NFToken is the same as the one that the
    // authorized minter minted in a previous ledger.
    if ((*sleAccount)[~sfFirstNFTokenSequence].value_or(0) +
            (*sleAccount)[~sfMintedNFTokens].value_or(0) + kSeqDelta >
        ctx.view.seq())
        return tecTOO_SOON;
 
    // Verify that the account does not own any objects that would prevent
    // the account from being deleted.
    Keylet const ownerDirKeylet{keylet::ownerDir(account)};
    if (dirIsEmpty(ctx.view, ownerDirKeylet))
        return tesSUCCESS;
 
    SLE::const_pointer sleDirNode{};
    unsigned int uDirEntry{0};
    uint256 dirEntry{beast::kZero};
 
    // Account has no directory at all.  This _should_ have been caught
    // by the dirIsEmpty() check earlier, but it's okay to catch it here.
    if (!cdirFirst(ctx.view, ownerDirKeylet.key, sleDirNode, uDirEntry, dirEntry))
        return tesSUCCESS;
 
    std::uint32_t deletableDirEntryCount{0};
    do
    {
        // Make sure any directory node types that we find are the kind
        // we can delete.
        auto sleItem = ctx.view.read(keylet::child(dirEntry));
        if (!sleItem)
        {
            // Directory node has an invalid index.  Bail out.
            // LCOV_EXCL_START
            JLOG(ctx.j.fatal()) << "AccountDelete: directory node in ledger " << ctx.view.seq()
                                << " has index to object that is missing: " << to_string(dirEntry);
            return tefBAD_LEDGER;
            // LCOV_EXCL_STOP
        }
 
        LedgerEntryType const nodeType{safeCast<LedgerEntryType>((*sleItem)[sfLedgerEntryType])};
 
        if (nonObligationDeleter(nodeType) == nullptr)
            return tecHAS_OBLIGATIONS;
 
        // We found a deletable directory entry.  Count it.  If we find too
        // many deletable directory entries then bail out.
        if (++deletableDirEntryCount > kMaxDeletableDirEntries)
            return tefTOO_BIG;
 
    } while (cdirNext(ctx.view, ownerDirKeylet.key, sleDirNode, uDirEntry, dirEntry));
 
    return tesSUCCESS;
}
 
TER
AccountDelete::doApply()
{
    auto src = view().peek(keylet::account(accountID_));
    XRPL_ASSERT(src, "xrpl::AccountDelete::doApply : non-null source account");
 
    auto const dstID = ctx_.tx[sfDestination];
    auto dst = view().peek(keylet::account(dstID));
    XRPL_ASSERT(dst, "xrpl::AccountDelete::doApply : non-null destination account");
 
    if (!src || !dst)
        return tefBAD_LEDGER;  // LCOV_EXCL_LINE
 
    if (ctx_.tx.isFieldPresent(sfCredentialIDs))
    {
        if (auto err =
                verifyDepositPreauth(ctx_.tx, ctx_.view(), accountID_, dstID, dst, ctx_.journal);
            !isTesSuccess(err))
            return err;
    }
 
    Keylet const ownerDirKeylet{keylet::ownerDir(accountID_)};
    auto const ter = cleanupOnAccountDelete(
        view(),
        ownerDirKeylet,
        [&](LedgerEntryType nodeType,
            uint256 const& dirEntry,
            SLE::pointer& sleItem) -> std::pair<TER, SkipEntry> {
            if (auto deleter = nonObligationDeleter(nodeType))
            {
                TER const result{deleter(ctx_.registry, view(), accountID_, dirEntry, sleItem, j_)};
 
                return {result, SkipEntry::No};
            }
 
            // LCOV_EXCL_START
            UNREACHABLE(
                "xrpl::AccountDelete::doApply : undeletable item not found "
                "in preclaim");
            JLOG(j_.error()) << "AccountDelete undeletable item not "
                                "found in preclaim.";
            return {tecHAS_OBLIGATIONS, SkipEntry::No};
            // LCOV_EXCL_STOP
        },
        ctx_.journal);
    if (!isTesSuccess(ter))
        return ter;
 
    // Transfer any XRP remaining after the fee is paid to the destination:
    auto const remainingBalance = src->getFieldAmount(sfBalance).xrp();
    (*dst)[sfBalance] = (*dst)[sfBalance] + remainingBalance;
    (*src)[sfBalance] = (*src)[sfBalance] - remainingBalance;
    ctx_.deliver(remainingBalance);
 
    if (src->isFieldPresent(sfSponsor))
    {
        auto const sponsorID = src->getAccountID(sfSponsor);
        auto sponsorSle = view().peek(keylet::account(sponsorID));
 
        if (!sponsorSle)
            return tefINTERNAL;  // LCOV_EXCL_LINE
 
        auto const sponsoringAccountCount = sponsorSle->getFieldU32(sfSponsoringAccountCount);
 
        XRPL_ASSERT(
            sponsoringAccountCount != 0,
            "xrpl::AccountDelete::doApply : sponsoring account count is present");
        if (sponsoringAccountCount == 0)
        {
            // sanity check
            // Since sfSponsoringAccountCount is set to soeDEFAULT, the field will not be
            // present with a value of 0.
            return tefINTERNAL;  // LCOV_EXCL_LINE
        }
        sponsorSle->at(sfSponsoringAccountCount) = sponsoringAccountCount - 1;
        view().update(sponsorSle);
 
        // Following line might look redundant, but without it, sfSponsor
        // would end up remaining in after-ltAccountRoot during the
        // InvariantCheck.
        src->makeFieldAbsent(sfSponsor);
    }
 
    XRPL_ASSERT(
        (*src)[sfBalance] == XRPAmount(0), "xrpl::AccountDelete::doApply : source balance is zero");
 
    // If there's still an owner directory associated with the source account
    // delete it.
    if (view().exists(ownerDirKeylet) && !view().emptyDirDelete(ownerDirKeylet))
    {
        JLOG(j_.error()) << "AccountDelete cannot delete root dir node of " << toBase58(accountID_);
        return tecHAS_OBLIGATIONS;
    }
 
    // Re-arm the password change fee if we can and need to.
    if (remainingBalance > XRPAmount(0) && dst->isFlag(lsfPasswordSpent))
        dst->clearFlag(lsfPasswordSpent);
 
    view().update(dst);
    view().erase(src);
 
    return tesSUCCESS;
}
 
void
AccountDelete::visitInvariantEntry(bool, SLE::const_ref, SLE::const_ref)
{
    // No transaction-specific invariants yet (future work).
}
 
bool
AccountDelete::finalizeInvariants(
    STTx const&,
    TER,
    XRPAmount,
    ReadView const&,
    beast::Journal const&)
{
    // No transaction-specific invariants yet (future work).
    return true;
}
 
}  // namespace xrpl