feat: simulate RPC to dry-run a tx (XLS-69d)

API-CHANGELOG.md

@@ -85,8 +85,9 @@ The `network_id` field was added in the `server_info` response in version 1.5.0
 
 ## XRP Ledger server version 2.4.0
 
-### Addition in 2.4
+### Additions in 2.4
 
+- `simulate`: A new RPC that executes a dry run of a transaction submission without actually submitting it to the network for inclusion.
 - `ledger_entry`: `state` is added an alias for `ripple_state`.
 
 ## XRP Ledger server version 2.3.0
@@ -97,7 +98,7 @@ The `network_id` field was added in the `server_info` response in version 1.5.0
 
 Admins can still attempt to retrieve old ledgers with the `ledger_request` RPC.
 
-### Addition in 2.3
+### Additions in 2.3
 
 - `book_changes`: Returns a `validated` field in its response, which was missing in prior versions.
 

include/xrpl/protocol/ErrorCodes.h

@@ -151,7 +151,10 @@ enum error_code_i {
     // deposit_authorized + credentials
     rpcBAD_CREDENTIALS = 95,
 
-    rpcLAST = rpcBAD_CREDENTIALS  // rpcLAST should always equal the last code.
+    // Simulate
+    rpcTX_SIGNED = 96,
+
+    rpcLAST = rpcTX_SIGNED  // rpcLAST should always equal the last code.
 };
 
 /** Codes returned in the `warnings` array of certain RPC commands.

include/xrpl/protocol/jss.h

@@ -88,6 +88,8 @@ JSS(SettleDelay);                        // in: TransactionSign
 JSS(SendMax);                            // in: TransactionSign
 JSS(Sequence);                           // in/out: TransactionSign; field.
 JSS(SetFlag);                            // field.
+JSS(Signer);                             // field.
+JSS(Signers);                            // field.
 JSS(SigningPubKey);                      // field.
 JSS(Subject);                            // in: Credential transactions
 JSS(TakerGets);                          // field.

src/libxrpl/protocol/ErrorCodes.cpp

@@ -109,7 +109,8 @@ constexpr static ErrorInfo unorderedErrorInfos[]{
     {rpcTXN_NOT_FOUND,          "txnNotFound",          "Transaction not found.", 404},
     {rpcUNKNOWN_COMMAND,        "unknownCmd",           "Unknown method.", 405},
     {rpcORACLE_MALFORMED,       "oracleMalformed",      "Oracle request is malformed.", 400},
-    {rpcBAD_CREDENTIALS,        "badCredentials",       "Credentials do not exist, are not accepted, or have expired.", 400}};
+    {rpcBAD_CREDENTIALS,        "badCredentials",       "Credentials do not exist, are not accepted, or have expired.", 400},
+    {rpcTX_SIGNED,              "transactionSigned",    "Transaction should not be signed.", 400}};
 // clang-format on
 
 // Sort and validate unorderedErrorInfos at compile time.  Should be

src/libxrpl/protocol/InnerObjectFormats.cpp

@@ -36,7 +36,7 @@ InnerObjectFormats::InnerObjectFormats()
             {sfWalletLocator, soeOPTIONAL},
         });
 
-    add(sfSigner.jsonName.c_str(),
+    add(sfSigner.jsonName,
         sfSigner.getCode(),
         {
             {sfAccount, soeREQUIRED},

src/test/app/NFToken_test.cpp

@@ -2239,7 +2239,7 @@ class NFTokenBaseUtil_test : public beast::unit_test::suite
             BEAST_EXPECT(env.balance(minter, gwXAU) == gwXAU(990));
 
             // minter sells the nft to alice.  Because alice is part of the
-            // transaction no tranfer fee is removed.
+            // transaction no transfer fee is removed.
             uint256 const minterSellOfferIndex =
                 keylet::nftoffer(minter, env.seq(minter)).key;
             env(token::createOffer(minter, nftID, gwXAU(10)),
@@ -2331,7 +2331,7 @@ class NFTokenBaseUtil_test : public beast::unit_test::suite
             BEAST_EXPECT(env.balance(carol, gwXAU) == gwXAU(990));
 
             // carol sells the nft to alice.  Because alice is part of the
-            // transaction no tranfer fee is removed.
+            // transaction no transfer fee is removed.
             uint256 const carolSellOfferIndex =
                 keylet::nftoffer(carol, env.seq(carol)).key;
             env(token::createOffer(carol, nftID, gwXAU(10)),

src/test/app/PseudoTx_test.cpp

@@ -92,8 +92,8 @@ struct PseudoTx_test : public beast::unit_test::suite
                 [&](OpenView& view, beast::Journal j) {
                     auto const result =
                         ripple::apply(env.app(), view, stx, tapNONE, j);
-                    BEAST_EXPECT(!result.second && result.first == temINVALID);
-                    return result.second;
+                    BEAST_EXPECT(!result.applied && result.ter == temINVALID);
+                    return result.applied;
                 });
         }
     }

src/test/app/Regression_test.cpp

@@ -76,8 +76,8 @@ struct Regression_test : public beast::unit_test::suite
 
             auto const result =
                 ripple::apply(env.app(), accum, *jt.stx, tapNONE, env.journal);
-            BEAST_EXPECT(result.first == tesSUCCESS);
-            BEAST_EXPECT(result.second);
+            BEAST_EXPECT(result.ter == tesSUCCESS);
+            BEAST_EXPECT(result.applied);
 
             accum.apply(*next);
         }
@@ -100,8 +100,8 @@ struct Regression_test : public beast::unit_test::suite
 
             auto const result =
                 ripple::apply(env.app(), accum, *jt.stx, tapNONE, env.journal);
-            BEAST_EXPECT(result.first == tecINSUFF_FEE);
-            BEAST_EXPECT(result.second);
+            BEAST_EXPECT(result.ter == tecINSUFF_FEE);
+            BEAST_EXPECT(result.applied);
 
             accum.apply(*next);
         }

src/test/app/TxQ_test.cpp

@@ -1062,11 +1062,10 @@ class TxQPosNegFlows_test : public beast::unit_test::suite
 
             env.app().openLedger().modify(
                 [&](OpenView& view, beast::Journal j) {
-                    // No need to initialize, since it's about to get set
-                    bool didApply;
-                    std::tie(parsed.ter, didApply) = ripple::apply(
+                    auto const result = ripple::apply(
                         env.app(), view, *jt.stx, tapNONE, env.journal);
-                    return didApply;
+                    parsed.ter = result.ter;
+                    return result.applied;
                 });
             env.postconditions(jt, parsed);
         }
@@ -4174,8 +4173,8 @@ class TxQPosNegFlows_test : public beast::unit_test::suite
                 env.jt(noop(alice), seq(aliceSeq), openLedgerFee(env));
             auto const result =
                 ripple::apply(env.app(), view, *tx.stx, tapUNLIMITED, j);
-            BEAST_EXPECT(result.first == tesSUCCESS && result.second);
-            return result.second;
+            BEAST_EXPECT(result.ter == tesSUCCESS && result.applied);
+            return result.applied;
         });
         // the queued transaction is still there
         checkMetrics(__LINE__, env, 1, std::nullopt, 5, 3, 256);
@@ -4246,8 +4245,8 @@ class TxQPosNegFlows_test : public beast::unit_test::suite
                 noop(alice), ticket::use(tktSeq0 + 1), openLedgerFee(env));
             auto const result =
                 ripple::apply(env.app(), view, *tx.stx, tapUNLIMITED, j);
-            BEAST_EXPECT(result.first == tesSUCCESS && result.second);
-            return result.second;
+            BEAST_EXPECT(result.ter == tesSUCCESS && result.applied);
+            return result.applied;
         });
         // the queued transaction is still there
         checkMetrics(__LINE__, env, 1, std::nullopt, 5, 3, 256);

src/test/consensus/NegativeUNL_test.cpp

@@ -1922,11 +1922,12 @@ negUnlSizeTest(
 bool
 applyAndTestResult(jtx::Env& env, OpenView& view, STTx const& tx, bool pass)
 {
-    auto res = apply(env.app(), view, tx, ApplyFlags::tapNONE, env.journal);
+    auto const res =
+        apply(env.app(), view, tx, ApplyFlags::tapNONE, env.journal);
     if (pass)
-        return res.first == tesSUCCESS;
+        return res.ter == tesSUCCESS;
     else
-        return res.first == tefFAILURE || res.first == temDISABLED;
+        return res.ter == tefFAILURE || res.ter == temDISABLED;
 }
 
 bool

src/test/rpc/JSONRPC_test.cpp

@@ -2160,6 +2160,28 @@ class JSONRPC_test : public beast::unit_test::suite
             BEAST_EXPECT(RPC::contains_error(result));
             BEAST_EXPECT(!req[jss::tx_json].isMember(jss::Fee));
         }
+
+        {
+            // transaction with a higher base fee
+            Json::Value req;
+            test::jtx::Account const alice("alice");
+            req[jss::tx_json] =
+                test::jtx::acctdelete(env.master.human(), alice.human());
+            Json::Value result = checkFee(
+                req,
+                Role::ADMIN,
+                true,
+                env.app().config(),
+                feeTrack,
+                env.app().getTxQ(),
+                env.app());
+
+            BEAST_EXPECT(result.size() == 0);
+            BEAST_EXPECT(
+                req[jss::tx_json].isMember(jss::Fee) &&
+                req[jss::tx_json][jss::Fee] ==
+                    env.current()->fees().increment.jsonClipped());
+        }
     }
 
     void