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Merge branch 'a1q123456/add-loan-invariants' into a1q123456/split-loan-set-and-loan-accept

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This commit is contained in:
JCW
2026-07-08 16:09:35 +01:00
parent 2b9c78a752 f2444ff61f
commit 080d5de281
2 changed files with 174 additions and 4 deletions
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14
src/libxrpl/tx/invariants/VaultInvariant.cpp
View File

@@ -1157,6 +1157,18 @@ ValidVault::finalize(
}
auto const& loan = afterLoan_[0];
// The created loan must record exactly the principal the vault
// released. Otherwise the borrower's claim (and thus the assets
// booked back to the vault on repayment) is decoupled from the
// assets actually lent, which would skew the vault's share price.
if (loan.principalOutstanding != tx[sfPrincipalRequested])
{
JLOG(j.fatal()) << //
"Invariant failed: loan set principal outstanding must "
"equal principal requested";
result = false;
}
// Interest accrues to the vault: assets outstanding must grow by
// exactly the interest due booked on the newly created loan.
auto const assetsTotalDelta = roundToAsset(
@@ -1420,8 +1432,8 @@ ValidVault::finalize(
return result;
}
// LCOV_EXCL_START
default:
// LCOV_EXCL_START
UNREACHABLE("xrpl::ValidVault::finalize : unknown transaction type");
return false;
// LCOV_EXCL_STOP

164
src/test/app/Invariants_test.cpp
View File

@@ -7,6 +7,7 @@
#include <test/jtx/mpt.h>
#include <test/jtx/pay.h>
#include <test/jtx/permissioned_domains.h>
#include <test/jtx/sig.h>
#include <test/jtx/tags.h>
#include <test/jtx/token.h>
#include <test/jtx/trust.h>
@@ -3449,7 +3450,8 @@ class Invariants_test : public beast::unit_test::Suite
.assetsAvailable = -100,
.vaultAssets = -100,
.accountAssets = AccountAmount{.account = a2.id(), .amount = 100},
.createLoan = LoanParams{}});
.createLoan =
LoanParams{.principalOutstanding = 200, .totalValueOutstanding = 200}});
},
XRPAmount{},
STTx{ttLOAN_SET, [](STObject& tx) { tx.at(sfPrincipalRequested) = Number(200); }},
@@ -3508,7 +3510,8 @@ class Invariants_test : public beast::unit_test::Suite
.assetsAvailable = -200,
.vaultAssets = -200,
.accountAssets = AccountAmount{.account = a2.id(), .amount = 200},
.createLoan = LoanParams{}});
.createLoan =
LoanParams{.principalOutstanding = 200, .totalValueOutstanding = 200}});
},
XRPAmount{},
STTx{ttLOAN_SET, [](STObject& tx) { tx.at(sfPrincipalRequested) = Number(200); }},
@@ -3529,7 +3532,58 @@ class Invariants_test : public beast::unit_test::Suite
.vaultAssets = -200,
.accountAssets = AccountAmount{.account = a2.id(), .amount = 200},
.accountShares = AccountAmount{.account = a2.id(), .amount = 10},
.createLoan = LoanParams{}});
.createLoan =
LoanParams{.principalOutstanding = 200, .totalValueOutstanding = 200}});
},
XRPAmount{},
STTx{ttLOAN_SET, [](STObject& tx) { tx.at(sfPrincipalRequested) = Number(200); }},
{tecINVARIANT_FAILED, tecINVARIANT_FAILED},
precloseXrp);
// ttLOAN_SET: everything balances (principal released, exactly one loan
// created booking zero interest so assets outstanding is unchanged, and
// shares are untouched), but the vault has a positive assets maximum
// below its assets outstanding, so only the maximum check trips.
doInvariantCheck(
{"loan set assets outstanding must not exceed assets maximum"},
[&](Account const& a1, Account const& a2, ApplyContext& ac) {
auto const keylet = keylet::vault(a1.id(), ac.view().seq());
return kAdjust(
ac.view(),
keylet,
Adjustments{
.assetsAvailable = -200,
.assetsMaximum = 1,
.vaultAssets = -200,
.accountAssets = AccountAmount{.account = a2.id(), .amount = 200},
.createLoan =
LoanParams{.principalOutstanding = 200, .totalValueOutstanding = 200}});
},
XRPAmount{},
STTx{ttLOAN_SET, [](STObject& tx) { tx.at(sfPrincipalRequested) = Number(200); }},
{tecINVARIANT_FAILED, tecINVARIANT_FAILED},
precloseXrp);
// ttLOAN_SET: everything balances (principal released, exactly one loan
// created booking zero interest, shares untouched, assets outstanding
// unchanged), but the created loan records a principal outstanding that
// differs from the principal requested. The vault only released 200 to
// the borrower, yet the loan claims 300 principal, decoupling the
// borrower's debt from the assets actually lent and enabling share-price
// manipulation on repayment.
doInvariantCheck(
{"loan set principal outstanding must equal principal requested"},
[&](Account const& a1, Account const& a2, ApplyContext& ac) {
auto const keylet = keylet::vault(a1.id(), ac.view().seq());
return kAdjust(
ac.view(),
keylet,
Adjustments{
.assetsAvailable = -200,
.vaultAssets = -200,
.accountAssets = AccountAmount{.account = a2.id(), .amount = 200},
.createLoan =
LoanParams{.principalOutstanding = 300, .totalValueOutstanding = 300}});
},
XRPAmount{},
STTx{ttLOAN_SET, [](STObject& tx) { tx.at(sfPrincipalRequested) = Number(200); }},
@@ -3814,6 +3868,74 @@ class Invariants_test : public beast::unit_test::Suite
"the change in the loan claim"));
}
// A loan may only be deleted by a LoanDelete transaction, and only once
// it is fully paid off. Both branches are exercised by creating a real
// loan in the Preclose (so it exists in the base ledger with outstanding
// principal) and then erasing it in the Precheck.
{
Keylet loanKeylet = keylet::amendments();
auto const precloseLoan = [&loanKeylet, this](
Account const& a1, Account const& a2, Env& env) -> bool {
PrettyAsset const xrpAsset{xrpIssue(), 1'000'000};
Vault const vault{env};
auto [tx, vaultKeylet] = vault.create({.owner = a1, .asset = xrpAsset});
env(tx);
env.close();
if (!BEAST_EXPECT(env.le(vaultKeylet)))
return false;
env(vault.deposit(
{.depositor = a1, .id = vaultKeylet.key, .amount = xrpAsset(100)}));
env.close();
auto const brokerKeylet = keylet::loanBroker(a1.id(), env.seq(a1));
env(loanBroker::set(a1, vaultKeylet.key), Fee(kIncrement));
env.close();
auto const brokerSle = env.le(brokerKeylet);
if (!BEAST_EXPECT(brokerSle))
return false;
loanKeylet = keylet::loan(brokerKeylet.key, brokerSle->at(sfLoanSequence));
env(loan::set(a2, brokerKeylet.key, xrpAsset(50).value()),
Sig(sfCounterpartySignature, a1),
Fee(env.current()->fees().base * 2));
env.close();
return BEAST_EXPECT(env.le(loanKeylet));
};
auto const eraseLoan = [&loanKeylet](Account const&, Account const&, ApplyContext& ac) {
auto sle = ac.view().peek(loanKeylet);
if (!sle)
return false;
ac.view().erase(sle);
return true;
};
// Deleting the loan under any transaction type other than LoanDelete
// (here the neutral ttACCOUNT_SET) is a violation, even while the
// loan still has outstanding obligations: the transaction-type check
// fires before the not-fully-paid-off check.
doInvariantCheck(
{"Loan deleted by a transaction other than LoanDelete"},
eraseLoan,
XRPAmount{},
STTx{ttACCOUNT_SET, [](STObject&) {}},
{tecINVARIANT_FAILED, tefINVARIANT_FAILED},
precloseLoan);
// Deleting the loan via LoanDelete while it still has outstanding
// obligations is a violation: the transaction-type check passes and
// the not-fully-paid-off check fires.
doInvariantCheck(
{"Loan deleted while not fully paid off"},
eraseLoan,
XRPAmount{},
STTx{ttLOAN_DELETE, [](STObject&) {}},
{tecINVARIANT_FAILED, tefINVARIANT_FAILED},
precloseLoan);
}
// LoanAccept restrictions: LoanAccept may only modify a loan that is
// pending acceptance, and the OwnerNode of an existing loan may only
// be added (never removed or changed), and only by LoanAccept. These
@@ -3952,6 +4074,42 @@ class Invariants_test : public beast::unit_test::Suite
return true;
});
// Each of these loan STNumber fields must never be negative. A neutral
// transaction type is used so the vault invariants short-circuit and
// only the loan check fires. The loan is created directly with a single
// field set negative while the paid-off bookkeeping is kept consistent
// so that only the "<field> is negative" check trips.
for (auto const field : {
&sfLoanServiceFee,
&sfLatePaymentFee,
&sfClosePaymentFee,
&sfPrincipalOutstanding,
&sfTotalValueOutstanding,
&sfManagementFeeOutstanding,
})
{
// The outstanding-balance fields also feed the paid-off checks, so
// a loan carrying one must still have payments remaining; a loan
// with only a negative fee stays fully paid off (zero remaining).
bool const isOutstanding = *field == sfPrincipalOutstanding ||
*field == sfTotalValueOutstanding || *field == sfManagementFeeOutstanding;
doInvariantCheck(
{field->getName() + " is negative"},
[&, field](Account const& a1, Account const&, ApplyContext& ac) {
auto const vaultKeylet = keylet::vault(a1.id(), ac.view().seq());
auto const loanKeylet = keylet::loan(vaultKeylet.key, 1);
auto sleLoan = std::make_shared<SLE>(loanKeylet);
sleLoan->at(sfPrincipalOutstanding) = Number(0);
sleLoan->at(sfTotalValueOutstanding) = Number(0);
sleLoan->at(sfManagementFeeOutstanding) = Number(0);
sleLoan->at(sfPeriodicPayment) = Number(1);
sleLoan->at(*field) = Number(-10);
sleLoan->setFieldU32(sfPaymentRemaining, isOutstanding ? 1 : 0);
ac.view().insert(sleLoan);
return true;
});
}
// ttVAULT_SET: owner is immutable
doInvariantCheck(
{"violation of vault immutable data"},