SetSignerList.cpp

#include <xrpld/app/ledger/Ledger.h>
#include <xrpld/app/tx/detail/SetSignerList.h>
 
#include <xrpl/basics/Log.h>
#include <xrpl/ledger/ApplyView.h>
#include <xrpl/protocol/Feature.h>
#include <xrpl/protocol/Indexes.h>
#include <xrpl/protocol/STArray.h>
#include <xrpl/protocol/STObject.h>
#include <xrpl/protocol/STTx.h>
#include <xrpl/protocol/TxFlags.h>
 
#include <algorithm>
#include <cstdint>
 
namespace xrpl {
 
// We're prepared for there to be multiple signer lists in the future,
// but we don't need them yet.  So for the time being we're manually
// setting the sfSignerListID to zero in all cases.
static std::uint32_t const DEFAULT_SIGNER_LIST_ID = 0;
 
std::tuple<NotTEC, std::uint32_t, std::vector<SignerEntries::SignerEntry>, SetSignerList::Operation>
SetSignerList::determineOperation(STTx const& tx, ApplyFlags flags, beast::Journal j)
{
    // Check the quorum.  A non-zero quorum means we're creating or replacing
    // the list.  A zero quorum means we're destroying the list.
    auto const quorum = tx[sfSignerQuorum];
    std::vector<SignerEntries::SignerEntry> sign;
    Operation op = unknown;
 
    bool const hasSignerEntries(tx.isFieldPresent(sfSignerEntries));
    if (quorum && hasSignerEntries)
    {
        auto signers = SignerEntries::deserialize(tx, j, "transaction");
 
        if (!signers)
            return std::make_tuple(signers.error(), quorum, sign, op);
 
        std::sort(signers->begin(), signers->end());
 
        // Save deserialized list for later.
        sign = std::move(*signers);
        op = set;
    }
    else if ((quorum == 0) && !hasSignerEntries)
    {
        op = destroy;
    }
 
    return std::make_tuple(tesSUCCESS, quorum, sign, op);
}
 
std::uint32_t
SetSignerList::getFlagsMask(PreflightContext const& ctx)
{
    // 0 means "Allow any flags"
    return ctx.rules.enabled(fixInvalidTxFlags) ? tfUniversalMask : 0;
}
 
NotTEC
SetSignerList::preflight(PreflightContext const& ctx)
{
    auto const result = determineOperation(ctx.tx, ctx.flags, ctx.j);
 
    if (std::get<0>(result) != tesSUCCESS)
        return std::get<0>(result);
 
    if (std::get<3>(result) == unknown)
    {
        // Neither a set nor a destroy.  Malformed.
        JLOG(ctx.j.trace()) << "Malformed transaction: Invalid signer set list format.";
        return temMALFORMED;
    }
 
    if (std::get<3>(result) == set)
    {
        // Validate our settings.
        auto const account = ctx.tx.getAccountID(sfAccount);
        NotTEC const ter =
            validateQuorumAndSignerEntries(std::get<1>(result), std::get<2>(result), account, ctx.j, ctx.rules);
        if (ter != tesSUCCESS)
        {
            return ter;
        }
    }
 
    return tesSUCCESS;
}
 
TER
SetSignerList::doApply()
{
    // Perform the operation preCompute() decided on.
    switch (do_)
    {
        case set:
            return replaceSignerList();
 
        case destroy:
            return destroySignerList();
 
        default:
            break;
    }
    // LCOV_EXCL_START
    UNREACHABLE("xrpl::SetSignerList::doApply : invalid operation");
    return temMALFORMED;
    // LCOV_EXCL_STOP
}
 
void
SetSignerList::preCompute()
{
    // Get the quorum and operation info.
    auto result = determineOperation(ctx_.tx, view().flags(), j_);
    XRPL_ASSERT(std::get<0>(result) == tesSUCCESS, "xrpl::SetSignerList::preCompute : result is tesSUCCESS");
    XRPL_ASSERT(std::get<3>(result) != unknown, "xrpl::SetSignerList::preCompute : result is known operation");
 
    quorum_ = std::get<1>(result);
    signers_ = std::get<2>(result);
    do_ = std::get<3>(result);
 
    return Transactor::preCompute();
}
 
// The return type is signed so it is compatible with the 3rd argument
// of adjustOwnerCount() (which must be signed).
static int
signerCountBasedOwnerCountDelta(std::size_t entryCount, Rules const& rules)
{
    // We always compute the full change in OwnerCount, taking into account:
    //  o The fact that we're adding/removing a SignerList and
    //  o Accounting for the number of entries in the list.
    // We can get away with that because lists are not adjusted incrementally;
    // we add or remove an entire list.
    //
    // The rule is:
    //  o Simply having a SignerList costs 2 OwnerCount units.
    //  o And each signer in the list costs 1 more OwnerCount unit.
    // So, at a minimum, adding a SignerList with 1 entry costs 3 OwnerCount
    // units.  A SignerList with 8 entries would cost 10 OwnerCount units.
    //
    // The static_cast should always be safe since entryCount should always
    // be in the range from 1 to 32.
    // We've got a lot of room to grow.
    XRPL_ASSERT(entryCount >= STTx::minMultiSigners, "xrpl::signerCountBasedOwnerCountDelta : minimum signers");
    XRPL_ASSERT(entryCount <= STTx::maxMultiSigners, "xrpl::signerCountBasedOwnerCountDelta : maximum signers");
    return 2 + static_cast<int>(entryCount);
}
 
static TER
removeSignersFromLedger(
    Application& app,
    ApplyView& view,
    Keylet const& accountKeylet,
    Keylet const& ownerDirKeylet,
    Keylet const& signerListKeylet,
    beast::Journal j)
{
    // We have to examine the current SignerList so we know how much to
    // reduce the OwnerCount.
    SLE::pointer signers = view.peek(signerListKeylet);
 
    // If the signer list doesn't exist we've already succeeded in deleting it.
    if (!signers)
        return tesSUCCESS;
 
    // There are two different ways that the OwnerCount could be managed.
    // If the lsfOneOwnerCount bit is set then remove just one owner count.
    // Otherwise use the pre-MultiSignReserve amendment calculation.
    int removeFromOwnerCount = -1;
    if ((signers->getFlags() & lsfOneOwnerCount) == 0)
    {
        STArray const& actualList = signers->getFieldArray(sfSignerEntries);
        removeFromOwnerCount = signerCountBasedOwnerCountDelta(actualList.size(), view.rules()) * -1;
    }
 
    // Remove the node from the account directory.
    auto const hint = (*signers)[sfOwnerNode];
 
    if (!view.dirRemove(ownerDirKeylet, hint, signerListKeylet.key, false))
    {
        // LCOV_EXCL_START
        JLOG(j.fatal()) << "Unable to delete SignerList from owner.";
        return tefBAD_LEDGER;
        // LCOV_EXCL_STOP
    }
 
    adjustOwnerCount(view, view.peek(accountKeylet), removeFromOwnerCount, app.journal("View"));
 
    view.erase(signers);
 
    return tesSUCCESS;
}
 
TER
SetSignerList::removeFromLedger(Application& app, ApplyView& view, AccountID const& account, beast::Journal j)
{
    auto const accountKeylet = keylet::account(account);
    auto const ownerDirKeylet = keylet::ownerDir(account);
    auto const signerListKeylet = keylet::signers(account);
 
    return removeSignersFromLedger(app, view, accountKeylet, ownerDirKeylet, signerListKeylet, j);
}
 
NotTEC
SetSignerList::validateQuorumAndSignerEntries(
    std::uint32_t quorum,
    std::vector<SignerEntries::SignerEntry> const& signers,
    AccountID const& account,
    beast::Journal j,
    Rules const& rules)
{
    // Reject if there are too many or too few entries in the list.
    {
        std::size_t const signerCount = signers.size();
        if (signerCount < STTx::minMultiSigners || signerCount > STTx::maxMultiSigners)
        {
            JLOG(j.trace()) << "Too many or too few signers in signer list.";
            return temMALFORMED;
        }
    }
 
    // Make sure there are no duplicate signers.
    XRPL_ASSERT(
        std::is_sorted(signers.begin(), signers.end()),
        "xrpl::SetSignerList::validateQuorumAndSignerEntries : sorted "
        "signers");
    if (std::adjacent_find(signers.begin(), signers.end()) != signers.end())
    {
        JLOG(j.trace()) << "Duplicate signers in signer list";
        return temBAD_SIGNER;
    }
 
    // Make sure no signers reference this account.  Also make sure the
    // quorum can be reached.
    std::uint64_t allSignersWeight(0);
    for (auto const& signer : signers)
    {
        std::uint32_t const weight = signer.weight;
        if (weight <= 0)
        {
            JLOG(j.trace()) << "Every signer must have a positive weight.";
            return temBAD_WEIGHT;
        }
 
        allSignersWeight += signer.weight;
 
        if (signer.account == account)
        {
            JLOG(j.trace()) << "A signer may not self reference account.";
            return temBAD_SIGNER;
        }
        // Don't verify that the signer accounts exist.  Non-existent accounts
        // may be phantom accounts (which are permitted).
    }
    if ((quorum <= 0) || (allSignersWeight < quorum))
    {
        JLOG(j.trace()) << "Quorum is unreachable";
        return temBAD_QUORUM;
    }
    return tesSUCCESS;
}
 
TER
SetSignerList::replaceSignerList()
{
    auto const accountKeylet = keylet::account(account_);
    auto const ownerDirKeylet = keylet::ownerDir(account_);
    auto const signerListKeylet = keylet::signers(account_);
 
    // This may be either a create or a replace.  Preemptively remove any
    // old signer list.  May reduce the reserve, so this is done before
    // checking the reserve.
    if (TER const ter = removeSignersFromLedger(ctx_.app, view(), accountKeylet, ownerDirKeylet, signerListKeylet, j_))
        return ter;
 
    auto const sle = view().peek(accountKeylet);
    if (!sle)
        return tefINTERNAL;  // LCOV_EXCL_LINE
 
    // Compute new reserve.  Verify the account has funds to meet the reserve.
    std::uint32_t const oldOwnerCount{(*sle)[sfOwnerCount]};
 
    constexpr int addedOwnerCount = 1;
    std::uint32_t flags{lsfOneOwnerCount};
 
    XRPAmount const newReserve{view().fees().accountReserve(oldOwnerCount + addedOwnerCount)};
 
    // We check the reserve against the starting balance because we want to
    // allow dipping into the reserve to pay fees.  This behavior is consistent
    // with CreateTicket.
    if (mPriorBalance < newReserve)
        return tecINSUFFICIENT_RESERVE;
 
    // Everything's ducky.  Add the ltSIGNER_LIST to the ledger.
    auto signerList = std::make_shared<SLE>(signerListKeylet);
    view().insert(signerList);
    writeSignersToSLE(signerList, flags);
 
    auto viewJ = ctx_.app.journal("View");
    // Add the signer list to the account's directory.
    auto const page = ctx_.view().dirInsert(ownerDirKeylet, signerListKeylet, describeOwnerDir(account_));
 
    JLOG(j_.trace()) << "Create signer list for account " << toBase58(account_) << ": "
                     << (page ? "success" : "failure");
 
    if (!page)
        return tecDIR_FULL;  // LCOV_EXCL_LINE
 
    signerList->setFieldU64(sfOwnerNode, *page);
 
    // If we succeeded, the new entry counts against the
    // creator's reserve.
    adjustOwnerCount(view(), sle, addedOwnerCount, viewJ);
    return tesSUCCESS;
}
 
TER
SetSignerList::destroySignerList()
{
    auto const accountKeylet = keylet::account(account_);
    // Destroying the signer list is only allowed if either the master key
    // is enabled or there is a regular key.
    SLE::pointer ledgerEntry = view().peek(accountKeylet);
    if (!ledgerEntry)
        return tefINTERNAL;  // LCOV_EXCL_LINE
 
    if ((ledgerEntry->isFlag(lsfDisableMaster)) && (!ledgerEntry->isFieldPresent(sfRegularKey)))
        return tecNO_ALTERNATIVE_KEY;
 
    auto const ownerDirKeylet = keylet::ownerDir(account_);
    auto const signerListKeylet = keylet::signers(account_);
    return removeSignersFromLedger(ctx_.app, view(), accountKeylet, ownerDirKeylet, signerListKeylet, j_);
}
 
void
SetSignerList::writeSignersToSLE(SLE::pointer const& ledgerEntry, std::uint32_t flags) const
{
    // Assign the quorum, default SignerListID, and flags.
    if (ctx_.view().rules().enabled(fixIncludeKeyletFields))
    {
        ledgerEntry->setAccountID(sfOwner, account_);
    }
    ledgerEntry->setFieldU32(sfSignerQuorum, quorum_);
    ledgerEntry->setFieldU32(sfSignerListID, DEFAULT_SIGNER_LIST_ID);
    if (flags)  // Only set flags if they are non-default (default is zero).
        ledgerEntry->setFieldU32(sfFlags, flags);
 
    // Create the SignerListArray one SignerEntry at a time.
    STArray toLedger(signers_.size());
    for (auto const& entry : signers_)
    {
        toLedger.push_back(STObject::makeInnerObject(sfSignerEntry));
        STObject& obj = toLedger.back();
        obj.reserve(2);
        obj[sfAccount] = entry.account;
        obj[sfSignerWeight] = entry.weight;
 
        // This is a defensive check to make absolutely sure we will never write
        // a tag into the ledger.
        if (entry.tag)
            obj.setFieldH256(sfWalletLocator, *(entry.tag));
    }
 
    // Assign the SignerEntries.
    ledgerEntry->setFieldArray(sfSignerEntries, toLedger);
}
 
}  // namespace xrpl