Dump transaction version as an unsigned integer in RPC/TxToUniv

Consensus-wise we already treat it as an unsigned integer (the
only rules around it are in CSV/locktime handling), but changing
the underlying data type means touching consensus code for a
simple cleanup change, which isn't really worth it.

See-also, rust-bitcoin/rust-bitcoin#299

Author: TheBlueMatt

doc/release-notes-16525.md

@@ -0,0 +1,7 @@
+RPC changes
+-----------
+
+Exposed transaction version numbers are now treated as unsigned 32-bit integers
+instead of signed 32-bit integers. This matches their treatment in consensus
+logic. Versions greater than 2 continue to be non-standard (matching previous
+behavior of smaller than 1 or greater than 2 being non-standard).

src/core_write.cpp

@@ -179,7 +179,9 @@ void TxToUniv(const CTransaction& tx, const uint256& hashBlock, UniValue& entry,
 {
     entry.pushKV("txid", tx.GetHash().GetHex());
     entry.pushKV("hash", tx.GetWitnessHash().GetHex());
-    entry.pushKV("version", tx.nVersion);
+    // Transaction version is actually unsigned in consensus checks, just signed in memory,
+    // so cast to unsigned before giving it to the user.
+    entry.pushKV("version", static_cast<int64_t>(static_cast<uint32_t>(tx.nVersion)));
     entry.pushKV("size", (int)::GetSerializeSize(tx, PROTOCOL_VERSION));
     entry.pushKV("vsize", (GetTransactionWeight(tx) + WITNESS_SCALE_FACTOR - 1) / WITNESS_SCALE_FACTOR);
     entry.pushKV("weight", GetTransactionWeight(tx));

test/functional/rpc_rawtransaction.py

@@ -417,11 +417,12 @@ def run_test(self):
         ####################################
 
         # Test the minimum transaction version number that fits in a signed 32-bit integer.
+        # As transaction version is unsigned, this should convert to its unsigned equivalent.
         tx = CTransaction()
         tx.nVersion = -0x80000000
         rawtx = ToHex(tx)
         decrawtx = self.nodes[0].decoderawtransaction(rawtx)
-        assert_equal(decrawtx['version'], -0x80000000)
+        assert_equal(decrawtx['version'], 0x80000000)
 
         # Test the maximum transaction version number that fits in a signed 32-bit integer.
         tx = CTransaction()