Merge bitcoin/bitcoin#22918: rpc: Add level 3 verbosity to getblock RPC call (#21245 modified)

5c34507ecbbdc29c086276d1c62835b461823507 core_write: Rename calculate_fee to have_undo for clarity (fyquah)
8edf6204a87057a451160d1e61e79d8be112e81f release-notes: Add release note about getblock verbosity level 3. (fyquah)
459104b2aae6eeaadfa5a7e47944f1a34780dacd rest: Add test for prevout fields in getblock (fyquah)
4330af6f72172848f5971a052a8f325ed50eb576 rpc: Add test for level 3 verbosity getblock rpc call. (fyquah)
51dbc167e98daab317baa80cf80bfda337672dab rpc: Add level 3 verbosity to getblock RPC call. (fyquah)
3cc95345ca49b87e8caca9a0e6418c63ae1e463a rpc: Replace boolean argument for tx details with enum class. (fyquah)

Pull request description:

  Author of #21245 expressed [time issues](https://github.com/bitcoin/bitcoin/pull/21245#issuecomment-902332088) in the original PR. Given that #21245 has received a lot of review*, I have decided to open this new pull request with [modifications required to get ACK from luke-jr ](https://github.com/bitcoin/bitcoin/pull/21245#issuecomment-905150806) and a few nits of mine.

  ### Original PR description

  > Display the prevout in transaction inputs when calling getblock level 3 verbosity. This PR affects the existing `/rest/block` API by adding a `prevout` fields to tx inputs. This is mentioned in the change to the release notes.
  >
  > I added some functional tests that
  >
  >     * checks that the RPC call still works when TxUndo can't be found
  >
  >     * Doesn't display the "value" or "scriptPubKey" of the previous output when at a lower verbosity level
  >
  >
  > This "completes" the issue #18771

  ### Possible improvements

  * https://github.com/kiminuo/bitcoin/commit/b0bf4f255f86aeaddce68889087c22f9068f4d97 - I can include even this commit to this PR if deemed useful or I can leave it for a follow-up PR. See https://github.com/bitcoin/bitcoin/pull/21245#issuecomment-894853784 for more context.

  ### Examples

  Examples of the `getblock` output with various verbose levels. Note that `000000000000001f682b188971cc1a121546be4e9d5baf22934fdc7f538288d5` contains only 2 transactions.

  #### Verbose level 0

  ```bash
  ./bitcoin-cli -testnet getblock 000000000000001f682b188971cc1a121546be4e9d5baf22934fdc7f538288d5 0
  ```

  ##### Verbose level 1

  ```bash
  ./bitcoin-cli -testnet getblock 000000000000001f682b188971cc1a121546be4e9d5baf22934fdc7f538288d5 1
  ```

  ##### Verbose level 2

  ```bash
  ./bitcoin-cli -testnet getblock 000000000000001f682b188971cc1a121546be4e9d5baf22934fdc7f538288d5 2
  ```

  ##### Verbose level 3

  ```bash
  ./bitcoin-cli -testnet getblock 000000000000001f682b188971cc1a121546be4e9d5baf22934fdc7f538288d5 3
  ```

  #### REST

  ```bash
  curl -H "content-type:text/plain;" http://127.0.0.1:18332/rest/block/000000000000001f682b188971cc1a121546be4e9d5baf22934fdc7f538288d5.json
  ```

  <sub>* ... and my everyday obsessive checking of my email inbox whether the PR moves forward.</sub>

  Edit laanwj: Removed at symbol from message, and large example output to prevent it from all ending up in the commit message.

ACKs for top commit:
  0xB10C:
    ACK 5c34507ecbbdc29c086276d1c62835b461823507
  meshcollider:
    utACK 5c34507ecbbdc29c086276d1c62835b461823507
  theStack:
    ACK 5c34507ecbbdc29c086276d1c62835b461823507 👘
  promag:
    Concept ACK 5c34507ecbbdc29c086276d1c62835b461823507

Tree-SHA512: bbff120d8fd76e617b723b102b0c606e0d8eb27f21c631d5f4cdab0892137c4bc7c65b1df144993405f942c91be47a26e80480102af55bff22621c19f518aea3

6 files changed, 78 insertions, 32 deletions

diff --git a/src/bench/rpc_blockchain.cpp b/src/bench/rpc_blockchain.cpp
index c8886a4c23..3bef64f720 100644
--- a/src/bench/rpc_blockchain.cpp
+++ b/src/bench/rpc_blockchain.cpp
@@ -40,7 +40,7 @@ static void BlockToJsonVerbose(benchmark::Bench& bench)
 {
     TestBlockAndIndex data;
     bench.run([&] {
-        auto univalue = blockToJSON(data.block, &data.blockindex, &data.blockindex, /*verbose*/ true);
+        auto univalue = blockToJSON(data.block, &data.blockindex, &data.blockindex, TxVerbosity::SHOW_DETAILS_AND_PREVOUT);
         ankerl::nanobench::doNotOptimizeAway(univalue);
     });
 }
@@ -50,7 +50,7 @@ BENCHMARK(BlockToJsonVerbose);
 static void BlockToJsonVerboseWrite(benchmark::Bench& bench)
 {
     TestBlockAndIndex data;
-    auto univalue = blockToJSON(data.block, &data.blockindex, &data.blockindex, /*verbose*/ true);
+    auto univalue = blockToJSON(data.block, &data.blockindex, &data.blockindex, TxVerbosity::SHOW_DETAILS_AND_PREVOUT);
     bench.run([&] {
         auto str = univalue.write();
         ankerl::nanobench::doNotOptimizeAway(str);
diff --git a/src/core_io.h b/src/core_io.h
index be93a17efe..4d7199ab12 100644
--- a/src/core_io.h
+++ b/src/core_io.h
@@ -20,6 +20,15 @@ class uint256;
 class UniValue;
 class CTxUndo;
 
+/**
+ * Verbose level for block's transaction
+ */
+enum class TxVerbosity {
+    SHOW_TXID,                //!< Only TXID for each block's transaction
+    SHOW_DETAILS,             //!< Include TXID, inputs, outputs, and other common block's transaction information
+    SHOW_DETAILS_AND_PREVOUT  //!< The same as previous option with information about prevouts if available
+};
+
 // core_read.cpp
 CScript ParseScript(const std::string& s);
 std::string ScriptToAsmStr(const CScript& script, const bool fAttemptSighashDecode = false);
@@ -46,6 +55,6 @@ std::string EncodeHexTx(const CTransaction& tx, const int serializeFlags = 0);
 std::string SighashToStr(unsigned char sighash_type);
 void ScriptPubKeyToUniv(const CScript& scriptPubKey, UniValue& out, bool include_hex, bool include_address = true);
 void ScriptToUniv(const CScript& script, UniValue& out);
-void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry, bool include_hex = true, int serialize_flags = 0, const CTxUndo* txundo = nullptr);
+void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry, bool include_hex = true, int serialize_flags = 0, const CTxUndo* txundo = nullptr, TxVerbosity verbosity = TxVerbosity::SHOW_DETAILS);
 
 #endif // BITCOIN_CORE_IO_H
diff --git a/src/core_write.cpp b/src/core_write.cpp
index 6b13e4c586..468694b011 100644
--- a/src/core_write.cpp
+++ b/src/core_write.cpp
@@ -163,7 +163,7 @@ void ScriptPubKeyToUniv(const CScript& scriptPubKey, UniValue& out, bool include
     out.pushKV("type", GetTxnOutputType(type));
 }
 
-void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry, bool include_hex, int serialize_flags, const CTxUndo* txundo)
+void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry, bool include_hex, int serialize_flags, const CTxUndo* txundo, TxVerbosity verbosity)
 {
     entry.pushKV("txid", tx.GetHash().GetHex());
     entry.pushKV("hash", tx.GetWitnessHash().GetHex());
@@ -179,7 +179,7 @@ void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry,
 
     // If available, use Undo data to calculate the fee. Note that txundo == nullptr
     // for coinbase transactions and for transactions where undo data is unavailable.
-    const bool calculate_fee = txundo != nullptr;
+    const bool have_undo = txundo != nullptr;
     CAmount amt_total_in = 0;
     CAmount amt_total_out = 0;
 
@@ -203,9 +203,28 @@ void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry,
             }
             in.pushKV("txinwitness", txinwitness);
         }
-        if (calculate_fee) {
-            const CTxOut& prev_txout = txundo->vprevout[i].out;
+        if (have_undo) {
+            const Coin& prev_coin = txundo->vprevout[i];
+            const CTxOut& prev_txout = prev_coin.out;
+
             amt_total_in += prev_txout.nValue;
+            switch (verbosity) {
+                case TxVerbosity::SHOW_TXID:
+                case TxVerbosity::SHOW_DETAILS:
+                    break;
+
+                case TxVerbosity::SHOW_DETAILS_AND_PREVOUT:
+                    UniValue o_script_pub_key(UniValue::VOBJ);
+                    ScriptPubKeyToUniv(prev_txout.scriptPubKey, o_script_pub_key, /* includeHex */ true);
+
+                    UniValue p(UniValue::VOBJ);
+                    p.pushKV("generated", bool(prev_coin.fCoinBase));
+                    p.pushKV("height", uint64_t(prev_coin.nHeight));
+                    p.pushKV("value", ValueFromAmount(prev_txout.nValue));
+                    p.pushKV("scriptPubKey", o_script_pub_key);
+                    in.pushKV("prevout", p);
+                    break;
+            }
         }
         in.pushKV("sequence", (int64_t)txin.nSequence);
         vin.push_back(in);
@@ -226,13 +245,13 @@ void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry,
         out.pushKV("scriptPubKey", o);
         vout.push_back(out);
 
-        if (calculate_fee) {
+        if (have_undo) {
             amt_total_out += txout.nValue;
         }
     }
     entry.pushKV("vout", vout);
 
-    if (calculate_fee) {
+    if (have_undo) {
         const CAmount fee = amt_total_in - amt_total_out;
         CHECK_NONFATAL(MoneyRange(fee));
         entry.pushKV("fee", ValueFromAmount(fee));
diff --git a/src/rest.cpp b/src/rest.cpp
index f6e34c2d81..3746fd752a 100644
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -262,7 +262,7 @@ static bool rest_headers(const std::any& context,
 static bool rest_block(const std::any& context,
                        HTTPRequest* req,
                        const std::string& strURIPart,
-                       bool showTxDetails)
+                       TxVerbosity tx_verbosity)
 {
     if (!CheckWarmup(req))
         return false;
@@ -314,7 +314,7 @@ static bool rest_block(const std::any& context,
     }
 
     case RetFormat::JSON: {
-        UniValue objBlock = blockToJSON(block, tip, pblockindex, showTxDetails);
+        UniValue objBlock = blockToJSON(block, tip, pblockindex, tx_verbosity);
         std::string strJSON = objBlock.write() + "\n";
         req->WriteHeader("Content-Type", "application/json");
         req->WriteReply(HTTP_OK, strJSON);
@@ -329,12 +329,12 @@ static bool rest_block(const std::any& context,
 
 static bool rest_block_extended(const std::any& context, HTTPRequest* req, const std::string& strURIPart)
 {
-    return rest_block(context, req, strURIPart, true);
+    return rest_block(context, req, strURIPart, TxVerbosity::SHOW_DETAILS_AND_PREVOUT);
 }
 
 static bool rest_block_notxdetails(const std::any& context, HTTPRequest* req, const std::string& strURIPart)
 {
-    return rest_block(context, req, strURIPart, false);
+    return rest_block(context, req, strURIPart, TxVerbosity::SHOW_TXID);
 }
 
 // A bit of a hack - dependency on a function defined in rpc/blockchain.cpp
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index fc99c8eed9..dadd82e03f 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -200,7 +200,7 @@ UniValue blockheaderToJSON(const CBlockIndex* tip, const CBlockIndex* blockindex
     return result;
 }
 
-UniValue blockToJSON(const CBlock& block, const CBlockIndex* tip, const CBlockIndex* blockindex, bool txDetails)
+UniValue blockToJSON(const CBlock& block, const CBlockIndex* tip, const CBlockIndex* blockindex, TxVerbosity verbosity)
 {
     UniValue result = blockheaderToJSON(tip, blockindex);
 
@@ -208,22 +208,29 @@ UniValue blockToJSON(const CBlock& block, const CBlockIndex* tip, const CBlockIn
     result.pushKV("size", (int)::GetSerializeSize(block, PROTOCOL_VERSION));
     result.pushKV("weight", (int)::GetBlockWeight(block));
     UniValue txs(UniValue::VARR);
-    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(), txundo);
-            txs.push_back(objTx);
-        }
-    } else {
-        for (const CTransactionRef& tx : block.vtx) {
-            txs.push_back(tx->GetHash().GetHex());
-        }
+
+    switch (verbosity) {
+        case TxVerbosity::SHOW_TXID:
+            for (const CTransactionRef& tx : block.vtx) {
+                txs.push_back(tx->GetHash().GetHex());
+            }
+            break;
+
+        case TxVerbosity::SHOW_DETAILS:
+        case TxVerbosity::SHOW_DETAILS_AND_PREVOUT:
+            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.e. i == 0) doesn't have undo data
+                const CTxUndo* txundo = (have_undo && i > 0) ? &blockUndo.vtxundo.at(i - 1) : nullptr;
+                UniValue objTx(UniValue::VOBJ);
+                TxToUniv(*tx, uint256(), objTx, true, RPCSerializationFlags(), txundo, verbosity);
+                txs.push_back(objTx);
+            }
     }
+
     result.pushKV("tx", txs);
 
     return result;
@@ -931,7 +938,8 @@ static RPCHelpMan getblock()
     return RPCHelpMan{"getblock",
                 "\nIf verbosity is 0, returns a string that is serialized, hex-encoded data for block 'hash'.\n"
                 "If verbosity is 1, returns an Object with information about block <hash>.\n"
-                "If verbosity is 2, returns an Object with information about block <hash> and information about each transaction. \n",
+                "If verbosity is 2, returns an Object with information about block <hash> and information about each transaction.\n"
+                "If verbosity is 3, returns an Object with information about block <hash> and information about each transaction, including prevout information for inputs (only for unpruned blocks in the current best chain).\n",
                 {
                     {"blockhash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
                     {"verbosity|verbose", RPCArg::Type::NUM, RPCArg::Default{1}, "0 for hex-encoded data, 1 for a json object, and 2 for json object with transaction data"},
@@ -1018,7 +1026,16 @@ static RPCHelpMan getblock()
         return strHex;
     }
 
-    return blockToJSON(block, tip, pblockindex, verbosity >= 2);
+    TxVerbosity tx_verbosity;
+    if (verbosity == 1) {
+        tx_verbosity = TxVerbosity::SHOW_TXID;
+    } else if (verbosity == 2) {
+        tx_verbosity = TxVerbosity::SHOW_DETAILS;
+    } else {
+        tx_verbosity = TxVerbosity::SHOW_DETAILS_AND_PREVOUT;
+    }
+
+    return blockToJSON(block, tip, pblockindex, tx_verbosity);
 },
     };
 }
diff --git a/src/rpc/blockchain.h b/src/rpc/blockchain.h
index 09e471afdd..d9c6761f47 100644
--- a/src/rpc/blockchain.h
+++ b/src/rpc/blockchain.h
@@ -6,6 +6,7 @@
 #define BITCOIN_RPC_BLOCKCHAIN_H
 
 #include <consensus/amount.h>
+#include <core_io.h>
 #include <streams.h>
 #include <sync.h>
 
@@ -38,7 +39,7 @@ double GetDifficulty(const CBlockIndex* blockindex);
 void RPCNotifyBlockChange(const CBlockIndex*);
 
 /** Block description to JSON */
-UniValue blockToJSON(const CBlock& block, const CBlockIndex* tip, const CBlockIndex* blockindex, bool txDetails = false) LOCKS_EXCLUDED(cs_main);
+UniValue blockToJSON(const CBlock& block, const CBlockIndex* tip, const CBlockIndex* blockindex, TxVerbosity verbosity) LOCKS_EXCLUDED(cs_main);
 
 /** Mempool information to JSON */
 UniValue MempoolInfoToJSON(const CTxMemPool& pool);