Merge #18772: rpc: calculate fees in getblock using BlockUndo data

66d012ad7f9381bacfc9b8388fa2ebf82cb86c9e test: RPC: getblock fee calculations (Elliott Jin)
bf7d6e31b1062ab5f90e14e83c56309f499fa2e9 RPC: getblock: tx fee calculation for verbosity 2 via Undo data (Elliott Jin)

Pull request description:

  This change is progress towards #18771 .  It adapts the fee calculation part of #16083 and addresses some feedback.  The additional "verbosity level 3" features are planned for a future PR.

  **Original PR description:**

  > Using block undo data (like in #14802) we can now show fee information for each transaction in a block without the need for additional -txindex and/or a ton of costly lookups. For a start we'll add transaction fee information to getblock verbosity level 2. This comes at a negligible speed penalty (<1%).

ACKs for top commit:
  luke-jr:
    tACK 66d012ad7f9381bacfc9b8388fa2ebf82cb86c9e
  fjahr:
    tACK 66d012ad7f9381bacfc9b8388fa2ebf82cb86c9e
  MarcoFalke:
    review ACK 66d012ad7f9381bacfc9b8388fa2ebf82cb86c9e 🗜

Tree-SHA512: be1fe4b866946a8dc36427f7dc72a20e10860e320a28fa49bc85bd2a93a0d699768179be29fa52e18b2ed8505d3ec272e586753ef2239b4230e0aefd233acaa2

1 files changed, 12 insertions, 6 deletions

diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 57327e6004..9047492642 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -172,16 +172,21 @@ UniValue blockToJSON(const CBlock& block, const CBlockIndex* tip, const CBlockIn
     result.pushKV("versionHex", strprintf("%08x", block.nVersion));
     result.pushKV("merkleroot", block.hashMerkleRoot.GetHex());
     UniValue txs(UniValue::VARR);
-    for(const auto& tx : block.vtx)
-    {
-        if(txDetails)
-        {
+    if (txDetails) {
+        CBlockUndo blockUndo;
+        const bool have_undo = !IsBlockPruned(blockindex) && UndoReadFromDisk(blockUndo, blockindex);
+        for (size_t i = 0; i < block.vtx.size(); ++i) {
+            const CTransactionRef& tx = block.vtx.at(i);
+            // coinbase transaction (i == 0) doesn't have undo data
+            const CTxUndo* txundo = (have_undo && i) ? &blockUndo.vtxundo.at(i - 1) : nullptr;
             UniValue objTx(UniValue::VOBJ);
-            TxToUniv(*tx, uint256(), objTx, true, RPCSerializationFlags());
+            TxToUniv(*tx, uint256(), objTx, true, RPCSerializationFlags(), txundo);
             txs.push_back(objTx);
         }
-        else
+    } else {
+        for (const CTransactionRef& tx : block.vtx) {
             txs.push_back(tx->GetHash().GetHex());
+        }
     }
     result.pushKV("tx", txs);
     result.pushKV("time", block.GetBlockTime());
@@ -936,6 +941,7 @@ static RPCHelpMan getblock()
                         {RPCResult::Type::OBJ, "", "",
                         {
                             {RPCResult::Type::ELISION, "", "The transactions in the format of the getrawtransaction RPC. Different from verbosity = 1 \"tx\" result"},
+                            {RPCResult::Type::NUM, "fee", "The transaction fee in " + CURRENCY_UNIT + ", omitted if block undo data is not available"},
                         }},
                     }},
                 }},