Create MPToken on AMMWithdraw if the token doesn't exist

src/test/app/MPToken_test.cpp

@@ -3127,14 +3127,26 @@ class MPToken_test : public beast::unit_test::suite
             auto const USD = gw["USD"];
             Env env(*this, features);
             fund(env, gw, {alice}, XRP(1'000), {USD(1'000)});
-            MPTTester mpt(env, gw, {.holders = {alice}, .fund = false});
-            mpt.create(
-                {.ownerCount = 1,
-                 .holderCount = 0,
-                 .flags = tfMPTCanTransfer | tfMPTCanTrade});
+            MPTTester mpt(env, gw, {.fund = false});
+            mpt.create({.flags = tfMPTCanTransfer | tfMPTCanTrade});
             auto const MPT = mpt["MPT"];
+            AMM amm(env, gw, MPT(100), XRP(100));
+            amm.deposit(DepositArg{.account = alice, .asset1In = XRP(10)});
+            amm::ammClawback(
+                gw, alice, MPTIssue(mpt.issuanceID()), xrpIssue(), MPT(10));
+        }
+
+        {
+            Account const gw{"gw"};
+            Account const alice{"alice"};
+            auto const USD = gw["USD"];
+            Env env(*this, features);
+            fund(env, gw, {alice}, XRP(1'000), {USD(1'000)});
+            MPTTester mpt(env, gw, {.fund = false});
+            mpt.create({.flags = tfMPTCanTransfer | tfMPTCanTrade});
             mpt.authorize({.account = alice});
             mpt.pay(gw, alice, 1'000);
+            auto const MPT = mpt["MPT"];
             AMM amm(env, gw, MPT(100), XRP(100));
             amm.deposit(DepositArg{.account = alice, .tokens = 10'000});
             amm::ammClawback(

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

@@ -345,8 +345,14 @@ applyCreate(
         // Authorize MPT
         if (amount.holds<MPTIssue>())
         {
-            auto const mptokenKey =
-                keylet::mptoken(amount.get<MPTIssue>().getMptID(), *ammAccount);
+            auto const& mptIssue = amount.get<MPTIssue>();
+            if (auto const err = requireAuth(
+                    ctx_.view(), mptIssue, account_, MPTAuthType::WeakAuth);
+                err != tesSUCCESS)
+                return err;
+
+            auto const& mptID = mptIssue.getMptID();
+            auto const mptokenKey = keylet::mptoken(mptID, *ammAccount);
 
             auto const ownerNode = sb.dirInsert(
                 keylet::ownerDir(*ammAccount),
@@ -358,7 +364,7 @@ applyCreate(
 
             auto mptoken = std::make_shared<SLE>(mptokenKey);
             (*mptoken)[sfAccount] = *ammAccount;
-            (*mptoken)[sfMPTokenIssuanceID] = amount.get<MPTIssue>().getMptID();
+            (*mptoken)[sfMPTokenIssuanceID] = mptID;
             (*mptoken)[sfFlags] = 0;
             (*mptoken)[sfOwnerNode] = *ownerNode;
             sb.insert(mptoken);

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

@@ -259,7 +259,8 @@ AMMDeposit::preclaim(PreclaimContext const& ctx)
         // Check if either of the assets is frozen, AMMDeposit is not allowed
         // if either asset is frozen
         auto checkAsset = [&](Asset const& asset) -> TER {
-            if (auto const ter = requireAuth(ctx.view, asset, accountID))
+            if (auto const ter = requireAuth(
+                    ctx.view, asset, accountID, MPTAuthType::WeakAuth))
             {
                 JLOG(ctx.j.debug())
                     << "AMM Deposit: account is not authorized, " << asset;

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

@@ -226,8 +226,11 @@ AMMWithdraw::preclaim(PreclaimContext const& ctx)
                     << *amount;
                 return tecAMM_BALANCE;
             }
-            if (auto const ter =
-                    requireAuth(ctx.view, amount->asset(), accountID))
+            if (auto const ter = requireAuth(
+                    ctx.view,
+                    amount->asset(),
+                    accountID,
+                    MPTAuthType::WeakAuth))
             {
                 JLOG(ctx.j.debug())
                     << "AMM Withdraw: account is not authorized, "
@@ -639,6 +642,61 @@ AMMWithdraw::withdraw(
     if (auto const err = sufficientReserve(amountWithdrawActual.issue()))
         return {err, STAmount{}, STAmount{}, STAmount{}};
 
+    // Create MPToken if doesn't exist
+    // TODO make a library, AMMCreate, AMMAuthorize use almost identical code
+    auto createMPToken = [&](Asset const& asset) -> TER {
+        if (asset.holds<MPTIssue>())
+        {
+            auto const& mptIssue = asset.get<MPTIssue>();
+            auto const issuanceKey = keylet::mptIssuance(mptIssue.getMptID());
+            auto const mptokenKey = keylet::mptoken(issuanceKey.key, account);
+            if (!view.exists(mptokenKey))
+            {
+                if (auto err = requireAuth(
+                        view, mptIssue, account, MPTAuthType::WeakAuth);
+                    err != tesSUCCESS)
+                    return err;
+            }
+
+            auto const sleAcct = view.peek(keylet::account(account));
+            if (!sleAcct)
+                return tefINTERNAL;
+
+            std::uint32_t const uOwnerCount =
+                sleAcct->getFieldU32(sfOwnerCount);
+            XRPAmount const reserveCreate(
+                (uOwnerCount < 2)
+                    ? XRPAmount(beast::zero)
+                    : view.fees().accountReserve(uOwnerCount + 1));
+
+            if (priorBalance < reserveCreate)
+                return tecINSUFFICIENT_RESERVE;
+
+            auto const ownerNode = view.dirInsert(
+                keylet::ownerDir(account),
+                mptokenKey,
+                describeOwnerDir(account));
+
+            if (!ownerNode)
+                return tecDIR_FULL;
+
+            auto mptoken = std::make_shared<SLE>(mptokenKey);
+            (*mptoken)[sfAccount] = account;
+            (*mptoken)[sfMPTokenIssuanceID] = mptIssue.getMptID();
+            (*mptoken)[sfFlags] = 0;
+            (*mptoken)[sfOwnerNode] = *ownerNode;
+            view.insert(mptoken);
+
+            // Update owner count.
+            adjustOwnerCount(view, sleAcct, 1, journal);
+        }
+        return tesSUCCESS;
+    };
+
+    if (auto const res = createMPToken(amountWithdrawActual.asset());
+        res != tesSUCCESS)
+        return {res, STAmount{}, STAmount{}, STAmount{}};
+
     // Withdraw amountWithdraw
     auto res = accountSend(
         view,
@@ -663,6 +721,10 @@ AMMWithdraw::withdraw(
             err != tesSUCCESS)
             return {err, STAmount{}, STAmount{}, STAmount{}};
 
+        if (auto const res = createMPToken(amountWithdrawActual.asset());
+            res != tesSUCCESS)
+            return {res, STAmount{}, STAmount{}, STAmount{}};
+
         res = accountSend(
             view,
             ammAccount,

src/xrpld/ledger/View.h

@@ -542,25 +542,41 @@ transferXRP(
     STAmount const& amount,
     beast::Journal j);
 
+/* Check if MPToken exists:
+ * - StrongAuth - before checking lsfMPTRequireAuth is set
+ * - WeakAuth - after checking if lsfMPTRequireAuth is set
+ */
+enum class MPTAuthType : bool { StrongAuth = true, WeakAuth = false };
+
 /** Check if the account lacks required authorization.
  *   Return tecNO_AUTH or tecNO_LINE if it does
  *   and tesSUCCESS otherwise.
  */
 [[nodiscard]] TER
 requireAuth(ReadView const& view, Issue const& issue, AccountID const& account);
+/* If StrongAuth then return tecNO_AUTH if MPToken doesn't exist or
+ * lsfMPTRequireAuth is set and MPToken is not authorized. If WeakAuth then
+ * return tecNO_AUTH if lsfMPTRequireAuth is set and MPToken doesn't exist or is
+ * not authorized.
+ */
 [[nodiscard]] TER
 requireAuth(
     ReadView const& view,
     MPTIssue const& mptIssue,
-    AccountID const& account);
+    AccountID const& account,
+    MPTAuthType authType = MPTAuthType::StrongAuth);
 [[nodiscard]] TER inline requireAuth(
     ReadView const& view,
     Asset const& asset,
-    AccountID const& account)
+    AccountID const& account,
+    MPTAuthType authType = MPTAuthType::StrongAuth)
 {
     return std::visit(
         [&]<ValidIssueType TIss>(TIss const& issue_) {
-            return requireAuth(view, issue_, account);
+            if constexpr (std::is_same_v<TIss, Issue>)
+                return requireAuth(view, issue_, account);
+            else
+                return requireAuth(view, issue_, account, authType);
         },
         asset.value());
 }

src/xrpld/ledger/detail/View.cpp

@@ -1867,7 +1867,8 @@ TER
 requireAuth(
     ReadView const& view,
     MPTIssue const& mptIssue,
-    AccountID const& account)
+    AccountID const& account,
+    MPTAuthType authType)
 {
     auto const mptID = keylet::mptIssuance(mptIssue.getMptID());
     auto const sleIssuance = view.read(mptID);
@@ -1885,12 +1886,12 @@ requireAuth(
     auto const sleToken = view.read(mptokenID);
 
     // if account has no MPToken, fail
-    if (!sleToken)
+    if (!sleToken && authType == MPTAuthType::StrongAuth)
         return tecNO_AUTH;
 
     // mptoken must be authorized if issuance enabled requireAuth
     if (sleIssuance->getFieldU32(sfFlags) & lsfMPTRequireAuth &&
-        !(sleToken->getFlags() & lsfMPTAuthorized))
+        (!sleToken || (!(sleToken->getFlags() & lsfMPTAuthorized))))
         return tecNO_AUTH;
 
     return tesSUCCESS;