extend escrow to psuedo and blackholed

- allow LP tokens
- allow blackholed accounts

include/xrpl/ledger/View.h

@@ -653,7 +653,8 @@ pseudoAccountAddress(ReadView const& view, uint256 const& pseudoOwnerKey);
 createPseudoAccount(
     ApplyView& view,
     uint256 const& pseudoOwnerKey,
-    SField const& ownerField);
+    SField const& ownerField,
+    std::uint32_t additionalFlags = 0);
 
 // Returns true iff sleAcct is a pseudo-account or specific
 // pseudo-accounts in pseudoFieldFilter.
@@ -688,6 +689,13 @@ isPseudoAccount(
         view.read(keylet::account(accountId)), pseudoFieldFilter);
 }
 
+// Returns true if the account is blackholed:
+// - lsfDisableMaster is set
+// - Regular key (if present) is AccountID(0), AccountID(1), or AccountID(2)
+// - No signer list exists
+[[nodiscard]] bool
+isBlackholed(ReadView const& view, std::shared_ptr<SLE const> const& sle);
+
 [[nodiscard]] TER
 canAddHolding(ReadView const& view, Asset const& asset);
 

src/libxrpl/ledger/View.cpp

@@ -1242,11 +1242,44 @@ isPseudoAccount(
             }) > 0;
 }
 
+[[nodiscard]] bool
+isBlackholed(ReadView const& view, std::shared_ptr<SLE const> const& sle)
+{
+    if (!sle || sle->getType() != ltACCOUNT_ROOT)
+        return false;
+
+    // If master key is not disabled, not blackholed
+    if (!sle->isFlag(lsfDisableMaster))
+        return false;
+
+    // If a regular key is set, it must be AccountID(0), AccountID(1), or
+    // AccountID(2) for the account to be blackholed
+    if (sle->isFieldPresent(sfRegularKey))
+    {
+        AccountID const rk = sle->getAccountID(sfRegularKey);
+        static AccountID const ACCOUNT_ZERO(0);
+        static AccountID const ACCOUNT_ONE(1);
+        static AccountID const ACCOUNT_TWO(2);
+
+        if (rk != ACCOUNT_ZERO && rk != ACCOUNT_ONE && rk != ACCOUNT_TWO)
+            return false;
+    }
+
+    // If a signer list is set, not blackholed
+    AccountID const account = sle->getAccountID(sfAccount);
+    if (view.exists(keylet::signers(account)))
+        return false;
+
+    // All conditions met: account is blackholed
+    return true;
+}
+
 Expected<std::shared_ptr<SLE>, TER>
 createPseudoAccount(
     ApplyView& view,
     uint256 const& pseudoOwnerKey,
-    SField const& ownerField)
+    SField const& ownerField,
+    std::uint32_t additionalFlags)
 {
     [[maybe_unused]]
     auto const& fields = getPseudoAccountFields();
@@ -1281,7 +1314,8 @@ createPseudoAccount(
     // rippling, and enable deposit authorization to prevent payments into
     // pseudo-account.
     account->setFieldU32(
-        sfFlags, lsfDisableMaster | lsfDefaultRipple | lsfDepositAuth);
+        sfFlags,
+        lsfDisableMaster | lsfDefaultRipple | lsfDepositAuth | additionalFlags);
     // Link the pseudo-account with its owner object.
     account->setFieldH256(ownerField, pseudoOwnerKey);
 

src/test/app/AMM_test.cpp

@@ -130,6 +130,48 @@ private:
         BEAST_EXPECT(
             STIssue(sfAsset, STAmount(XRP(2'000)).issue()) !=
             STIssue(sfAsset, STAmount(USD(2'000)).issue()));
+
+        // AMM account flags with fixTokenEscrowV1_1
+        // New AMM accounts should have lsfAllowTrustLineLocking set
+        {
+            Env env{*this, testable_amendments()};
+            fund(env, gw, {alice}, {USD(20'000)}, Fund::All);
+            AMM ammAlice(env, alice, XRP(10'000), USD(10'000));
+            auto const ammAccount = ammAlice.ammAccount();
+
+            // Check that AMM account has expected flags
+            auto const sleAMM = env.le(keylet::account(ammAccount));
+            BEAST_EXPECT(sleAMM);
+            if (sleAMM)
+            {
+                // Base pseudo-account flags
+                BEAST_EXPECT(sleAMM->isFlag(lsfDisableMaster));
+                BEAST_EXPECT(sleAMM->isFlag(lsfDefaultRipple));
+                BEAST_EXPECT(sleAMM->isFlag(lsfDepositAuth));
+                BEAST_EXPECT(sleAMM->isFlag(lsfAllowTrustLineLocking));
+            }
+        }
+
+        // AMM account flags without fixTokenEscrowV1_1
+        // New AMM accounts should NOT have lsfAllowTrustLineLocking
+        {
+            Env env{*this, testable_amendments() - fixTokenEscrowV1_1};
+            fund(env, gw, {alice}, {USD(20'000)}, Fund::All);
+            AMM ammAlice(env, alice, XRP(10'000), USD(10'000));
+            auto const ammAccount = ammAlice.ammAccount();
+
+            // Check that AMM account has expected flags
+            auto const sleAMM = env.le(keylet::account(ammAccount));
+            BEAST_EXPECT(sleAMM);
+            if (sleAMM)
+            {
+                // Base pseudo-account flags
+                BEAST_EXPECT(sleAMM->isFlag(lsfDisableMaster));
+                BEAST_EXPECT(sleAMM->isFlag(lsfDefaultRipple));
+                BEAST_EXPECT(sleAMM->isFlag(lsfDepositAuth));
+                BEAST_EXPECT(!sleAMM->isFlag(lsfAllowTrustLineLocking));
+            }
+        }
     }
 
     void

src/test/app/EscrowToken_test.cpp

@@ -1,4 +1,5 @@
 #include <test/jtx.h>
+#include <test/jtx/AMM.h>
 
 #include <xrpld/app/tx/applySteps.h>
 
@@ -359,6 +360,97 @@ struct EscrowToken_test : public beast::unit_test::suite
             env.close();
         }
 
+        // AMM issuer without asfAllowTrustLineLocking
+        // (succeeds under fixTokenEscrowV1_1, fails otherwise)
+        {
+            bool const withFix = features[fixTokenEscrowV1_1];
+            Env env{*this, features};
+            auto const baseFee = env.current()->fees().base;
+            auto const alice = Account("alice");
+            auto const bob = Account("bob");
+            auto const carol = Account("carol");
+            auto const gw = Account{"gateway"};
+
+            env.fund(XRP(30'000), alice, bob, carol, gw);
+            env.close();
+
+            // Create an AMM pool (XRP/USD)
+            auto const USD = gw["USD"];
+            env.trust(USD(30'000), alice);
+            env.close();
+            env(pay(gw, alice, USD(10'000)));
+            env.close();
+
+            AMM ammAlice(env, alice, XRP(10'000), USD(10'000));
+            auto const ammAccount = ammAlice.ammAccount();
+            auto const lpIssue = ammAlice.lptIssue();
+
+            // Carol gets LP tokens
+            env.trust(STAmount{lpIssue, 10'000}, carol);
+            env.close();
+            env(pay(alice, carol, STAmount{lpIssue, 100}));
+            env.close();
+
+            // Try to create escrow with AMM account as issuer (LP tokens)
+            env(escrow::create(carol, bob, STAmount{lpIssue, 50}),
+                escrow::finish_time(env.now() + 1s),
+                fee(baseFee * 150),
+                ter(withFix ? TER(tesSUCCESS) : TER(tecNO_PERMISSION)));
+            env.close();
+
+            if (withFix)
+            {
+                // Verify the AMM account now has lsfAllowTrustLineLocking
+                auto const sleAMM = env.le(keylet::account(ammAccount));
+                BEAST_EXPECT(
+                    sleAMM && sleAMM->isFlag(lsfAllowTrustLineLocking));
+            }
+        }
+
+        // Blackholed issuer without asfAllowTrustLineLocking
+        // (succeeds under fixTokenEscrowV1_1, fails otherwise)
+        {
+            bool const withFix = features[fixTokenEscrowV1_1];
+            Env env{*this, features};
+            auto const baseFee = env.current()->fees().base;
+            auto const alice = Account("alice");
+            auto const bob = Account("bob");
+            auto const gw = Account{"gateway"};
+            auto const USD = gw["USD"];
+
+            env.fund(XRP(5000), alice, bob, gw);
+            env.close();
+            env.trust(USD(10'000), alice, bob);
+            env.close();
+            env(pay(gw, alice, USD(5000)));
+            env(pay(gw, bob, USD(5000)));
+            env.close();
+
+            // Blackhole the gateway: set regular key to AccountID(1)
+            // (noAccount), then disable master key. AccountID(1) is a
+            // non-functional account that nobody can sign with.
+            Account const blackhole("blackhole", AccountID(1));
+            env(regkey(gw, blackhole));
+            env.close();
+            // Disable master key (must use master key to disable it)
+            env(fset(gw, asfDisableMaster), sig(gw));
+            env.close();
+
+            // Try to create escrow with blackholed issuer
+            env(escrow::create(alice, bob, USD(100)),
+                escrow::finish_time(env.now() + 1s),
+                fee(baseFee * 150),
+                ter(withFix ? TER(tesSUCCESS) : TER(tecNO_PERMISSION)));
+            env.close();
+
+            if (withFix)
+            {
+                // Verify the gateway now has lsfAllowTrustLineLocking
+                auto const sleGW = env.le(keylet::account(gw));
+                BEAST_EXPECT(sleGW && sleGW->isFlag(lsfAllowTrustLineLocking));
+            }
+        }
+
         // tecNO_LINE: account does not have a trustline to the issuer
         {
             Env env{*this, features};
@@ -4089,6 +4181,7 @@ public:
         testIOUWithFeats(all - fixTokenEscrowV1_1);
         testMPTWithFeats(all);
         testMPTWithFeats(all - fixTokenEscrowV1);
+        testMPTWithFeats(all - fixTokenEscrowV1 - fixTokenEscrowV1_1);
     }
 };
 

src/xrpld/app/tx/detail/AMMCreate.cpp

@@ -202,7 +202,10 @@ applyCreate(
     auto const ammKeylet = keylet::amm(amount.issue(), amount2.issue());
 
     // Mitigate same account exists possibility
-    auto const maybeAccount = createPseudoAccount(sb, ammKeylet.key, sfAMMID);
+    std::uint32_t const additionalFlags =
+        sb.rules().enabled(fixTokenEscrowV1_1) ? lsfAllowTrustLineLocking : 0;
+    auto const maybeAccount =
+        createPseudoAccount(sb, ammKeylet.key, sfAMMID, additionalFlags);
     // AMM account already exists (should not happen)
     if (!maybeAccount)
     {

src/xrpld/app/tx/detail/Escrow.cpp

@@ -184,7 +184,21 @@ escrowCreatePreclaimHelper<Issue>(
     if (!sleIssuer)
         return tecNO_ISSUER;
     if (!sleIssuer->isFlag(lsfAllowTrustLineLocking))
-        return tecNO_PERMISSION;
+    {
+        // fixTokenEscrowV1_1: allows escrow for AMM pseudo accounts and
+        // blackholed issuers
+        if (ctx.view.rules().enabled(fixTokenEscrowV1_1))
+        {
+            bool const isAMM = isPseudoAccount(sleIssuer, {&sfAMMID});
+            bool const isBlackholedIssuer = isBlackholed(ctx.view, sleIssuer);
+            if (!isAMM && !isBlackholedIssuer)
+                return tecNO_PERMISSION;
+        }
+        else
+        {
+            return tecNO_PERMISSION;
+        }
+    }
 
     // If the account does not have a trustline to the issuer, return tecNO_LINE
     auto const sleRippleState =
@@ -478,6 +492,27 @@ EscrowCreate::doApply()
         auto const xferRate = transferRate(ctx_.view(), amount);
         if (xferRate != parityRate)
             (*slep)[sfTransferRate] = xferRate.value;
+
+        // Add lsfAllowTrustLineLocking to AMM pseudo accounts and
+        // blackholed issuers under fixTokenEscrowV1_1
+        if (ctx_.view().rules().enabled(fixTokenEscrowV1_1))
+        {
+            AccountID const issuer = amount.getIssuer();
+            auto sleIssuer = ctx_.view().peek(keylet::account(issuer));
+            if (sleIssuer && !sleIssuer->isFlag(lsfAllowTrustLineLocking))
+            {
+                bool const isAMM = isPseudoAccount(sleIssuer, {&sfAMMID});
+                bool const isBlackholedIssuer =
+                    isBlackholed(ctx_.view(), sleIssuer);
+                if (isAMM || isBlackholedIssuer)
+                {
+                    sleIssuer->setFieldU32(
+                        sfFlags,
+                        sleIssuer->getFlags() | lsfAllowTrustLineLocking);
+                    ctx_.view().update(sleIssuer);
+                }
+            }
+        }
     }
 
     ctx_.view().insert(slep);
@@ -755,6 +790,13 @@ escrowUnlockApplyHelper<Issue>(
     bool createAsset,
     beast::Journal journal)
 {
+    // fixTokenEscrowV1_1: sleDest must be an account root
+    if (view.rules().enabled(fixTokenEscrowV1_1))
+    {
+        if (!sleDest || sleDest->getType() != ltACCOUNT_ROOT)
+            return tecINTERNAL;
+    }
+
     Keylet const trustLineKey = keylet::line(receiver, amount.issue());
     bool const recvLow = issuer > receiver;
     bool const senderIssuer = issuer == sender;
@@ -888,6 +930,13 @@ escrowUnlockApplyHelper<MPTIssue>(
     bool createAsset,
     beast::Journal journal)
 {
+    // fixTokenEscrowV1_1: sleDest must be an account root
+    if (view.rules().enabled(fixTokenEscrowV1_1))
+    {
+        if (!sleDest || sleDest->getType() != ltACCOUNT_ROOT)
+            return tecINTERNAL;
+    }
+
     bool const senderIssuer = issuer == sender;
     bool const receiverIssuer = issuer == receiver;
 

src/xrpld/app/tx/detail/InvariantCheck.cpp

@@ -1067,9 +1067,14 @@ ValidNewAccountRoot::finalize(
 
         if (pseudoAccount)
         {
-            std::uint32_t const expected =
+            std::uint32_t const base =
                 (lsfDisableMaster | lsfDefaultRipple | lsfDepositAuth);
-            if (flags_ != expected)
+            bool valid = (flags_ == base);
+            // fixTokenEscrowV1_1: pseudo accounts will also have
+            // lsfAllowTrustLineLocking set at creation time.
+            if (!valid && view.rules().enabled(fixTokenEscrowV1_1))
+                valid = (flags_ == (base | lsfAllowTrustLineLocking));
+            if (!valid)
             {
                 JLOG(j.fatal())
                     << "Invariant failed: pseudo-account created with "