Fix test: create trustlines before DisallowIncomingTrustline flag is set

Co-authored-by: mvadari <8029314+mvadari@users.noreply.github.com>

include/xrpl/protocol/detail/features.macro

@@ -16,6 +16,7 @@
 // Add new amendments to the top of this list.
 // Keep it sorted in reverse chronological order.
 
+XRPL_FIX    (DisallowIncomingV1_1,       Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FIX    (BatchInnerSigs,             Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(LendingProtocol,            Supported::yes, VoteBehavior::DefaultNo)
 XRPL_FEATURE(PermissionDelegationV1_1,   Supported::no,  VoteBehavior::DefaultNo)

src/test/app/Offer_test.cpp

@@ -4173,6 +4173,170 @@ public:
         env.require(balance(bob, gwUSD(10)));
     }
 
+    void
+    testDisallowIncomingTrustline(FeatureBitset features)
+    {
+        testcase("DisallowIncomingTrustline in OfferCreate");
+        // Test that asfDisallowIncomingTrustline flag prevents offer crossing
+        // when the taker doesn't have a trustline.
+        //
+        // 1. alice creates a trustline and sells USD/gw tokens.
+        //
+        // 2. gw sets asfDisallowIncomingTrustline flag.
+        //
+        // 3. An account without a trustline tries to create an offer for USD/gw.
+        //    Without amendment: succeeds and crosses alice's offer (backward compatible).
+        //    With amendment: fails with tecNO_LINE (new behavior).
+        //
+        // 4. An account WITH an existing trustline can create an offer.
+        //    The offer succeeds and crosses alice's offer.
+        //
+        // Note: The DisallowIncomingTrustline flag also prevents NEW trustlines
+        // from being created via TrustSet (enforced by fixDisallowIncomingV1).
+        // So accounts must create trustlines BEFORE the issuer sets the flag.
+
+        using namespace jtx;
+
+        // Test without fixDisallowIncomingV1_1 amendment
+        {
+            Env env{*this, features - fixDisallowIncomingV1_1};
+
+            auto const gw = Account("gw");
+            auto const alice = Account("alice");
+            auto const bob = Account("bob");
+            auto const gwUSD = gw["USD"];
+
+            env.fund(XRP(400000), gw, alice, bob);
+            env.close();
+
+            // Alice creates trustline and gets some USD
+            env(trust(alice, gwUSD(100)));
+            env.close();
+            env(pay(gw, alice, gwUSD(50)));
+            env.close();
+
+            // Alice creates sell offer
+            env(offer(alice, XRP(4000), gwUSD(40)));
+            env.close();
+            env.require(offers(alice, 1));
+
+            // GW sets DisallowIncomingTrustline flag
+            env(fset(gw, asfDisallowIncomingTrustline));
+            env.close();
+
+            // Without the amendment, bob can still create offer without trustline
+            // and the offer should cross (old behavior)
+            env(offer(bob, gwUSD(40), XRP(4000)));
+            env.close();
+
+            // Offer should have crossed
+            env.require(offers(alice, 0));
+            env.require(offers(bob, 0));
+            env.require(balance(bob, gwUSD(40)));
+        }
+
+        // Test with fixDisallowIncomingV1_1 amendment
+        {
+            Env env{*this, features};
+
+            auto const gw = Account("gw");
+            auto const alice = Account("alice");
+            auto const bob = Account("bob");
+            auto const carol = Account("carol");
+            auto const dan = Account("dan");
+            auto const gwUSD = gw["USD"];
+
+            env.fund(XRP(400000), gw, alice, bob, carol, dan);
+            env.close();
+
+            // Alice creates trustline and gets some USD
+            env(trust(alice, gwUSD(100)));
+            env.close();
+            env(pay(gw, alice, gwUSD(50)));
+            env.close();
+
+            // Bob and carol create trustlines BEFORE the flag is set
+            env(trust(bob, gwUSD(100)));
+            env.close();
+            env(trust(carol, gwUSD(100)));
+            env.close();
+
+            // Alice creates sell offer
+            env(offer(alice, XRP(4000), gwUSD(40)));
+            env.close();
+            env.require(offers(alice, 1));
+            env.require(balance(alice, gwUSD(50)));
+
+            // GW sets DisallowIncomingTrustline flag
+            env(fset(gw, asfDisallowIncomingTrustline));
+            env.close();
+
+            // Dan tries to create offer without trustline - should fail
+            env(offer(dan, gwUSD(40), XRP(4000)), ter(tecNO_LINE));
+            env.close();
+
+            // Alice's offer should still exist
+            env.require(offers(alice, 1));
+            env.require(balance(alice, gwUSD(50)));
+
+            // Dan shouldn't have any offers or balance
+            env.require(offers(dan, 0));
+            env.require(balance(dan, gwUSD(none)));
+
+            // Bob already has trustline, so his offer should succeed and cross
+            env(offer(bob, gwUSD(40), XRP(4000)));
+            env.close();
+
+            // Offer should have crossed
+            env.require(offers(alice, 0));
+            env.require(offers(bob, 0));
+            env.require(balance(alice, gwUSD(10)));
+            env.require(balance(bob, gwUSD(40)));
+
+            // Test scenario where carol already has a trustline (created before flag was set)
+            // Carol should be able to create offer since trustline already exists
+            env(pay(gw, alice, gwUSD(50)));
+            env.close();
+            env(offer(alice, XRP(1000), gwUSD(10)));
+            env.close();
+            env.require(offers(alice, 1));
+
+            env(offer(carol, gwUSD(10), XRP(1000)));
+            env.close();
+
+            // Offer should have crossed
+            env.require(offers(alice, 0));
+            env.require(offers(carol, 0));
+            env.require(balance(alice, gwUSD(50)));
+            env.require(balance(carol, gwUSD(10)));
+
+            // Test that gw can clear the flag
+            env(fclear(gw, asfDisallowIncomingTrustline));
+            env.close();
+
+            // Create new account eve without trustline
+            auto const eve = Account("eve");
+            env.fund(XRP(400000), eve);
+            env.close();
+
+            // Bob creates another sell offer
+            env(pay(gw, bob, gwUSD(50)));
+            env.close();
+            env(offer(bob, XRP(5000), gwUSD(50)));
+            env.close();
+            env.require(offers(bob, 1));
+
+            // Eve should now be able to create offer without trustline (flag is cleared)
+            env(offer(eve, gwUSD(50), XRP(5000)));
+            env.close();
+
+            // Offer should have crossed
+            env.require(offers(bob, 0));
+            env.require(offers(eve, 0));
+            env.require(balance(eve, gwUSD(50)));
+        }
+    }
+
     void
     testRCSmoketest(FeatureBitset features)
     {
@@ -5009,6 +5173,7 @@ public:
         testSelfPayUnlimitedFunds(features);
         testRequireAuth(features);
         testMissingAuth(features);
+        testDisallowIncomingTrustline(features);
         testRCSmoketest(features);
         testSelfAuth(features);
         testDeletedOfferIssuer(features);

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

@@ -216,10 +216,22 @@ CreateOffer::checkAcceptAsset(
         // An account can always accept its own issuance.
         return tesSUCCESS;
 
+    // Read the trustline once for multiple flag checks to optimize performance
+    auto const trustLine = view.read(keylet::line(id, issue.account, issue.currency));
+
+    // Check if the issuer has lsfDisallowIncomingTrustline set
+    // If so, the account must already have a trustline to receive tokens
+    if (view.rules().enabled(fixDisallowIncomingV1_1) && ((*issuerAccount)[sfFlags] & lsfDisallowIncomingTrustline))
+    {
+        if (!trustLine)
+        {
+            JLOG(j.debug()) << "delay: can't receive IOUs from issuer with DisallowIncomingTrustline set.";
+            return (flags & tapRETRY) ? TER{terNO_LINE} : TER{tecNO_LINE};
+        }
+    }
+
     if ((*issuerAccount)[sfFlags] & lsfRequireAuth)
     {
-        auto const trustLine = view.read(keylet::line(id, issue.account, issue.currency));
-
         if (!trustLine)
         {
             return (flags & tapRETRY) ? TER{terNO_LINE} : TER{tecNO_LINE};
@@ -248,8 +260,6 @@ CreateOffer::checkAcceptAsset(
         return tesSUCCESS;
     }
 
-    auto const trustLine = view.read(keylet::line(id, issue.account, issue.currency));
-
     if (!trustLine)
     {
         return tesSUCCESS;