[validation] change package-fee-too-low, return wtxid(s) and effective feerate

With subpackage evaluation and de-duplication, it's not always the
entire package that is used in CheckFeerate. To be more helpful to the
caller, specify which transactions were included in the evaluation and
what the feerate was.

Instead of PCKG_POLICY (which is supposed to be for package-wide
errors), use PCKG_TX.

1 files changed, 20 insertions, 8 deletions

diff --git a/src/validation.cpp b/src/validation.cpp
index c478252f18..018566fa9c 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -1237,7 +1237,13 @@ MempoolAcceptResult MemPoolAccept::AcceptSingleTransaction(const CTransactionRef
     Workspace ws(ptx);
     const std::vector<Wtxid> single_wtxid{ws.m_ptx->GetWitnessHash()};
 
-    if (!PreChecks(args, ws)) return MempoolAcceptResult::Failure(ws.m_state);
+    if (!PreChecks(args, ws)) {
+        if (ws.m_state.GetResult() == TxValidationResult::TX_RECONSIDERABLE) {
+            // Failed for fee reasons. Provide the effective feerate and which tx was included.
+            return MempoolAcceptResult::FeeFailure(ws.m_state, CFeeRate(ws.m_modified_fees, ws.m_vsize), single_wtxid);
+        }
+        return MempoolAcceptResult::Failure(ws.m_state);
+    }
 
     if (m_rbf && !ReplacementChecks(ws)) return MempoolAcceptResult::Failure(ws.m_state);
 
@@ -1254,7 +1260,12 @@ MempoolAcceptResult MemPoolAccept::AcceptSingleTransaction(const CTransactionRef
                                             ws.m_base_fees, effective_feerate, single_wtxid);
     }
 
-    if (!Finalize(args, ws)) return MempoolAcceptResult::Failure(ws.m_state);
+    if (!Finalize(args, ws)) {
+        // The only possible failure reason is fee-related (mempool full).
+        // Failed for fee reasons. Provide the effective feerate and which txns were included.
+        Assume(ws.m_state.GetResult() == TxValidationResult::TX_RECONSIDERABLE);
+        return MempoolAcceptResult::FeeFailure(ws.m_state, CFeeRate(ws.m_modified_fees, ws.m_vsize), {ws.m_ptx->GetWitnessHash()});
+    }
 
     GetMainSignals().TransactionAddedToMempool(ptx, m_pool.GetAndIncrementSequence());
 
@@ -1308,11 +1319,16 @@ PackageMempoolAcceptResult MemPoolAccept::AcceptMultipleTransactions(const std::
     const auto m_total_modified_fees = std::accumulate(workspaces.cbegin(), workspaces.cend(), CAmount{0},
         [](CAmount sum, auto& ws) { return sum + ws.m_modified_fees; });
     const CFeeRate package_feerate(m_total_modified_fees, m_total_vsize);
+    std::vector<Wtxid> all_package_wtxids;
+    all_package_wtxids.reserve(workspaces.size());
+    std::transform(workspaces.cbegin(), workspaces.cend(), std::back_inserter(all_package_wtxids),
+                   [](const auto& ws) { return ws.m_ptx->GetWitnessHash(); });
     TxValidationState placeholder_state;
     if (args.m_package_feerates &&
         !CheckFeeRate(m_total_vsize, m_total_modified_fees, placeholder_state)) {
-        package_state.Invalid(PackageValidationResult::PCKG_POLICY, "package-fee-too-low");
-        return PackageMempoolAcceptResult(package_state, {});
+        package_state.Invalid(PackageValidationResult::PCKG_TX, "transaction failed");
+        return PackageMempoolAcceptResult(package_state, {{workspaces.back().m_ptx->GetWitnessHash(),
+            MempoolAcceptResult::FeeFailure(placeholder_state, CFeeRate(m_total_modified_fees, m_total_vsize), all_package_wtxids)}});
     }
 
     // Apply package mempool ancestor/descendant limits. Skip if there is only one transaction,
@@ -1323,10 +1339,6 @@ PackageMempoolAcceptResult MemPoolAccept::AcceptMultipleTransactions(const std::
         return PackageMempoolAcceptResult(package_state, std::move(results));
     }
 
-    std::vector<Wtxid> all_package_wtxids;
-    all_package_wtxids.reserve(workspaces.size());
-    std::transform(workspaces.cbegin(), workspaces.cend(), std::back_inserter(all_package_wtxids),
-                   [](const auto& ws) { return ws.m_ptx->GetWitnessHash(); });
     for (Workspace& ws : workspaces) {
         ws.m_package_feerate = package_feerate;
         if (!PolicyScriptChecks(args, ws)) {