fix(AMM): prevent orphaned objects, inconsistent ledger state: (updates XLS-30)

API-CHANGELOG.md

@@ -47,6 +47,19 @@ Additions are intended to be non-breaking (because they are purely additive).
   - Adds the [Clawback transaction type](https://github.com/XRPLF/XRPL-Standards/blob/master/XLS-39d-clawback/README.md#331-clawback-transaction), containing these fields:
     - `Account`: The issuer of the asset being clawed back. Must also be the sender of the transaction.
     - `Amount`: The amount being clawed back, with the `Amount.issuer` being the token holder's address.
+- Adds [AMM](https://github.com/XRPLF/XRPL-Standards/discussions/78) ([#4294](https://github.com/XRPLF/rippled/pull/4294), [#4626](https://github.com/XRPLF/rippled/pull/4626)) feature:
+    - Adds `amm_info` API to retrieve AMM information for a given tokens pair.
+    - Adds `AMMCreate` transaction type to create `AMM` instance.
+    - Adds `AMMDeposit` transaction type to deposit funds into `AMM` instance.
+    - Adds `AMMWithdraw` transaction type to withdraw funds from `AMM` instance.
+    - Adds `AMMVote` transaction type to vote for the trading fee of `AMM` instance.
+    - Adds `AMMBid` transaction type to bid for the Auction Slot of `AMM` instance.
+    - Adds `AMMDelete` transaction type to delete `AMM` instance.
+    - Adds `lsfAMM` `AccountRoot` flag to indicate that the account is `AMM`'s account.
+    - Adds `lsfAMMNode` `TrustLine` flag to indicate that one side of the `TrustLine` is `AMM` account.
+    - Adds `tfLPToken`, `tfSingleAsset`, `tfTwoAsset`, `tfOneAssetLPToken`, `tfLimitLPToken`, `tfTwoAssetIfEmpty`,
+      `tfWithdrawAll`, `tfOneAssetWithdrawAll` which allow a trader to specify different fields combination 
+      for `AMMDeposit` and `AMMWithdraw` transactions.
 
 ## XRP Ledger version 1.11.0
 

Builds/CMake/RippledCore.cmake

@@ -476,6 +476,7 @@ target_sources (rippled PRIVATE
   src/ripple/app/rdb/impl/Wallet.cpp
   src/ripple/app/tx/impl/AMMBid.cpp
   src/ripple/app/tx/impl/AMMCreate.cpp
+  src/ripple/app/tx/impl/AMMDelete.cpp
   src/ripple/app/tx/impl/AMMDeposit.cpp
   src/ripple/app/tx/impl/AMMVote.cpp
   src/ripple/app/tx/impl/AMMWithdraw.cpp

src/ripple/app/misc/AMMUtils.h

@@ -93,6 +93,26 @@ ammAccountHolds(
     AccountID const& ammAccountID,
     Issue const& issue);
 
+/** Delete trustlines to AMM. If all trustlines are deleted then
+ * AMM object and account are deleted. Otherwise tecIMPCOMPLETE is returned.
+ */
+TER
+deleteAMMAccount(
+    ApplyView& view,
+    Issue const& asset,
+    Issue const& asset2,
+    beast::Journal j);
+
+/** Initialize Auction and Voting slots and set the trading/disconted fee.
+ */
+void
+initializeFeeAuctionVote(
+    ApplyView& view,
+    std::shared_ptr<SLE>& ammSle,
+    AccountID const& account,
+    Issue const& lptIssue,
+    std::uint16_t tfee);
+
 }  // namespace ripple
 
 #endif  // RIPPLE_APP_MISC_AMMUTILS_H_INLCUDED

src/ripple/app/misc/impl/AMMUtils.cpp

@@ -188,4 +188,110 @@ ammAccountHolds(
     return STAmount{issue};
 }
 
+static std::pair<TER, AllNodesDeleted>
+deleteAMMTrustLines(
+    ApplyView& view,
+    AccountID const& ammAccountID,
+    std::uint16_t maxTrustlinesToDelete,
+    beast::Journal j)
+{
+    return cleanupOnAccountDelete(
+        view,
+        keylet::ownerDir(ammAccountID),
+        [&](LedgerEntryType nodeType,
+            uint256 const&,
+            std::shared_ptr<SLE>& sleItem) -> TER {
+            // Should only have the trustlines
+            if (nodeType != LedgerEntryType::ltRIPPLE_STATE)
+            {
+                JLOG(j.error())
+                    << "deleteAMMTrustLines: deleting non-trustline "
+                    << nodeType;
+                return tecINTERNAL;
+            }
+
+            // Trustlines must have zero balance
+            if (sleItem->getFieldAmount(sfBalance) != beast::zero)
+            {
+                JLOG(j.error())
+                    << "deleteAMMTrustLines: deleting trustline with "
+                       "non-zero balance.";
+                return tecINTERNAL;
+            }
+
+            return deleteAMMTrustLine(view, sleItem, ammAccountID, j);
+        },
+        j,
+        maxTrustlinesToDelete);
+}
+
+TER
+deleteAMMAccount(
+    ApplyView& view,
+    Issue const& asset,
+    Issue const& asset2,
+    beast::Journal j)
+{
+    auto ammSle = view.peek(keylet::amm(asset, asset2));
+    if (!ammSle)
+        return tecINTERNAL;
+
+    auto const ammAccountID = (*ammSle)[sfAccount];
+    auto sleAMMRoot = view.peek(keylet::account(ammAccountID));
+    if (!sleAMMRoot)
+        return tecINTERNAL;
+
+    if (auto const res = deleteAMMTrustLines(
+            view, ammAccountID, maxDeletableAMMTrustLines, j);
+        std::get<TER>(res) != tesSUCCESS)
+        return std::get<TER>(res);
+    // All trustlines are deleted, can delete ltAMM and the account
+    else if (res.second == AllNodesDeleted::Yes)
+    {
+        view.erase(ammSle);
+        view.erase(sleAMMRoot);
+        return tesSUCCESS;
+    }
+
+    return tecINCOMPLETE;
+}
+
+void
+initializeFeeAuctionVote(
+    ApplyView& view,
+    std::shared_ptr<SLE>& ammSle,
+    AccountID const& account,
+    Issue const& lptIssue,
+    std::uint16_t tfee)
+{
+    // AMM creator gets the voting slot.
+    STArray voteSlots;
+    STObject voteEntry{sfVoteEntry};
+    if (tfee != 0)
+        voteEntry.setFieldU16(sfTradingFee, tfee);
+    voteEntry.setFieldU32(sfVoteWeight, 100000);
+    voteEntry.setAccountID(sfAccount, account);
+    voteSlots.push_back(voteEntry);
+    ammSle->setFieldArray(sfVoteSlots, voteSlots);
+    // AMM creator gets the auction slot for free.
+    auto& auctionSlot = ammSle->peekFieldObject(sfAuctionSlot);
+    auctionSlot.setAccountID(sfAccount, account);
+    // current + sec in 24h
+    auto const expiration = std::chrono::duration_cast<std::chrono::seconds>(
+                                view.info().parentCloseTime.time_since_epoch())
+                                .count() +
+        TOTAL_TIME_SLOT_SECS;
+    auctionSlot.setFieldU32(sfExpiration, expiration);
+    auctionSlot.setFieldAmount(sfPrice, STAmount{lptIssue, 0});
+    // Set the fee
+    if (tfee != 0)
+        ammSle->setFieldU16(sfTradingFee, tfee);
+    else if (ammSle->isFieldPresent(sfTradingFee))
+        ammSle->makeFieldAbsent(sfTradingFee);
+    if (auto const dfee = tfee / AUCTION_SLOT_DISCOUNTED_FEE_FRACTION)
+        auctionSlot.setFieldU16(sfDiscountedFee, dfee);
+    else if (auctionSlot.isFieldPresent(sfDiscountedFee))
+        auctionSlot.makeFieldAbsent(sfDiscountedFee);
+}
+
 }  // namespace ripple

src/ripple/app/paths/impl/BookStep.cpp

@@ -99,7 +99,8 @@ class BookStep : public StepImp<TIn, TOut, BookStep<TIn, TOut, TDerived>>
         , ownerPaysTransferFee_(ctx.ownerPaysTransferFee)
         , j_(ctx.j)
     {
-        if (auto const ammSle = ctx.view.read(keylet::amm(in, out)))
+        if (auto const ammSle = ctx.view.read(keylet::amm(in, out));
+            ammSle && ammSle->getFieldAmount(sfLPTokenBalance) != beast::zero)
             ammLiquidity_.emplace(
                 ctx.view,
                 (*ammSle)[sfAccount],

src/ripple/app/tx/impl/AMMBid.cpp

@@ -94,6 +94,10 @@ AMMBid::preclaim(PreclaimContext const& ctx)
         return terNO_AMM;
     }
 
+    auto const lpTokensBalance = (*ammSle)[sfLPTokenBalance];
+    if (lpTokensBalance == beast::zero)
+        return tecAMM_EMPTY;
+
     if (ctx.tx.isFieldPresent(sfAuthAccounts))
     {
         for (auto const& account : ctx.tx.getFieldArray(sfAuthAccounts))
@@ -114,7 +118,6 @@ AMMBid::preclaim(PreclaimContext const& ctx)
         JLOG(ctx.j.debug()) << "AMM Bid: account is not LP.";
         return tecAMM_INVALID_TOKENS;
     }
-    auto const lpTokensBalance = (*ammSle)[sfLPTokenBalance];
 
     auto const bidMin = ctx.tx[~sfBidMin];
 
@@ -204,10 +207,10 @@ applyBid(
                           Number const& burn) -> TER {
         auctionSlot.setAccountID(sfAccount, account_);
         auctionSlot.setFieldU32(sfExpiration, current + TOTAL_TIME_SLOT_SECS);
-        if (fee == 0)
-            auctionSlot.makeFieldAbsent(sfDiscountedFee);
-        else
+        if (fee != 0)
             auctionSlot.setFieldU16(sfDiscountedFee, fee);
+        else if (auctionSlot.isFieldPresent(sfDiscountedFee))
+            auctionSlot.makeFieldAbsent(sfDiscountedFee);
         auctionSlot.setFieldAmount(
             sfPrice, toSTAmount(lpTokens.issue(), minPrice));
         if (ctx_.tx.isFieldPresent(sfAuthAccounts))

src/ripple/app/tx/impl/AMMCreate.cpp

@@ -248,53 +248,25 @@ applyCreate(
     // either an AMMDeposit, TrustSet, crossing an offer, etc.
     sleAMMRoot->setFieldU32(
         sfFlags, lsfAMM | lsfDisableMaster | lsfDefaultRipple | lsfDepositAuth);
+    // Link the root account and AMM object
+    sleAMMRoot->setFieldH256(sfAMMID, ammKeylet.key);
     sb.insert(sleAMMRoot);
 
     // Calculate initial LPT balance.
     auto const lpTokens = ammLPTokens(amount, amount2, lptIss);
 
     // Create ltAMM
     auto ammSle = std::make_shared<SLE>(ammKeylet);
-    if (ctx_.tx[sfTradingFee] != 0)
-        ammSle->setFieldU16(sfTradingFee, ctx_.tx[sfTradingFee]);
     ammSle->setAccountID(sfAccount, *ammAccount);
     ammSle->setFieldAmount(sfLPTokenBalance, lpTokens);
     auto const& [issue1, issue2] = std::minmax(amount.issue(), amount2.issue());
     ammSle->setFieldIssue(sfAsset, STIssue{sfAsset, issue1});
     ammSle->setFieldIssue(sfAsset2, STIssue{sfAsset2, issue2});
-    // AMM creator gets the voting slot.
-    STArray voteSlots;
-    STObject voteEntry{sfVoteEntry};
-    if (ctx_.tx[sfTradingFee] != 0)
-        voteEntry.setFieldU16(sfTradingFee, ctx_.tx[sfTradingFee]);
-    voteEntry.setFieldU32(sfVoteWeight, 100000);
-    voteEntry.setAccountID(sfAccount, account_);
-    voteSlots.push_back(voteEntry);
-    ammSle->setFieldArray(sfVoteSlots, voteSlots);
-    // AMM creator gets the auction slot for free.
-    auto& auctionSlot = ammSle->peekFieldObject(sfAuctionSlot);
-    auctionSlot.setAccountID(sfAccount, account_);
-    // current + sec in 24h
-    auto const expiration =
-        std::chrono::duration_cast<std::chrono::seconds>(
-            ctx_.view().info().parentCloseTime.time_since_epoch())
-            .count() +
-        TOTAL_TIME_SLOT_SECS;
-    auctionSlot.setFieldU32(sfExpiration, expiration);
-    auctionSlot.setFieldAmount(sfPrice, STAmount{lpTokens.issue(), 0});
+    // AMM creator gets the auction slot and the voting slot.
+    initializeFeeAuctionVote(
+        ctx_.view(), ammSle, account_, lptIss, ctx_.tx[sfTradingFee]);
     sb.insert(ammSle);
 
-    // Add owner directory to link the root account and AMM object.
-    if (auto const page = sb.dirInsert(
-            keylet::ownerDir(*ammAccount),
-            ammSle->key(),
-            describeOwnerDir(*ammAccount));
-        !page)
-    {
-        JLOG(j_.debug()) << "AMM Instance: failed to insert owner dir";
-        return {tecDIR_FULL, false};
-    }
-
     // Send LPT to LP.
     auto res = accountSend(sb, *ammAccount, account_, lpTokens, ctx_.journal);
     if (res != tesSUCCESS)

src/ripple/app/tx/impl/AMMDelete.cpp

@@ -0,0 +1,89 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2022 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <ripple/app/tx/impl/AMMDelete.h>
+
+#include <ripple/app/misc/AMMUtils.h>
+#include <ripple/ledger/Sandbox.h>
+#include <ripple/protocol/AMMCore.h>
+#include <ripple/protocol/Feature.h>
+#include <ripple/protocol/STAccount.h>
+#include <ripple/protocol/TER.h>
+#include <ripple/protocol/TxFlags.h>
+
+namespace ripple {
+
+NotTEC
+AMMDelete::preflight(PreflightContext const& ctx)
+{
+    if (!ammEnabled(ctx.rules))
+        return temDISABLED;
+
+    if (auto const ret = preflight1(ctx); !isTesSuccess(ret))
+        return ret;
+
+    if (ctx.tx.getFlags() & tfUniversalMask)
+    {
+        JLOG(ctx.j.debug()) << "AMM Delete: invalid flags.";
+        return temINVALID_FLAG;
+    }
+
+    if (auto const res = invalidAMMAssetPair(ctx.tx[sfAsset], ctx.tx[sfAsset2]))
+    {
+        JLOG(ctx.j.debug()) << "AMM Delete: Invalid asset pair.";
+        return res;
+    }
+
+    return preflight2(ctx);
+}
+
+TER
+AMMDelete::preclaim(PreclaimContext const& ctx)
+{
+    auto const ammSle =
+        ctx.view.read(keylet::amm(ctx.tx[sfAsset], ctx.tx[sfAsset2]));
+    if (!ammSle)
+    {
+        JLOG(ctx.j.debug()) << "AMM Delete: Invalid asset pair.";
+        return terNO_AMM;
+    }
+
+    auto const lpTokensBalance = (*ammSle)[sfLPTokenBalance];
+    if (lpTokensBalance != beast::zero)
+        return tecAMM_EMPTY;
+
+    return tesSUCCESS;
+}
+
+TER
+AMMDelete::doApply()
+{
+    // This is the ledger view that we work against. Transactions are applied
+    // as we go on processing transactions.
+    Sandbox sb(&ctx_.view());
+
+    auto const ter =
+        deleteAMMAccount(sb, ctx_.tx[sfAsset], ctx_.tx[sfAsset2], j_);
+    if (ter == tesSUCCESS || ter == tecINCOMPLETE)
+        sb.apply(ctx_.rawView());
+
+    return ter;
+}
+
+}  // namespace ripple