consensus: Store transaction nVersion as uint32_t

Given that the use of a transaction's nVersion is always as an unsigned
int, it doesn't make sense to store it as signed and then cast it to
unsigned.

test/functional/feature_taproot.py

@@ -1410,7 +1410,7 @@ class TaprootTest(BitcoinTestFramework):
         while left:
             # Construct CTransaction with random nVersion, nLocktime
             tx = CTransaction()
-            tx.nVersion = random.choice([1, 2, random.randint(-0x80000000, 0x7fffffff)])
+            tx.nVersion = random.choice([1, 2, random.getrandbits(32)])
             min_sequence = (tx.nVersion != 1 and tx.nVersion != 0) * 0x80000000  # The minimum sequence number to disable relative locktime
             if random.choice([True, False]):
                 tx.nLockTime = random.randrange(LOCKTIME_THRESHOLD, self.lastblocktime - 7200)  # all absolute locktimes in the past

test/functional/p2p_segwit.py

@@ -1164,7 +1164,7 @@ class SegWitTest(BitcoinTestFramework):
                 if not self.wit.is_null():
                     flags |= 1
                 r = b""
-                r += self.nVersion.to_bytes(4, "little", signed=True)
+                r += self.nVersion.to_bytes(4, "little")
                 if flags:
                     dummy = []
                     r += ser_vector(dummy)
@@ -1975,7 +1975,7 @@ class SegWitTest(BitcoinTestFramework):
         def serialize_with_bogus_witness(tx):
             flags = 3
             r = b""
-            r += tx.nVersion.to_bytes(4, "little", signed=True)
+            r += tx.nVersion.to_bytes(4, "little")
             if flags:
                 dummy = []
                 r += ser_vector(dummy)

test/functional/rpc_packages.py

@@ -394,7 +394,7 @@ class RPCPackagesTest(BitcoinTestFramework):
         peer = node.add_p2p_connection(P2PTxInvStore())
         txs = self.wallet.create_self_transfer_chain(chain_length=2)
         bad_child = tx_from_hex(txs[1]["hex"])
-        bad_child.nVersion = -1
+        bad_child.nVersion = 0xffffffff
         hex_partial_acceptance = [txs[0]["hex"], bad_child.serialize().hex()]
         res = node.submitpackage(hex_partial_acceptance)
         assert_equal(res["package_msg"], "transaction failed")

test/functional/rpc_rawtransaction.py

@@ -463,9 +463,9 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.log.info("Test transaction version numbers")
 
         # 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.
+        # As transaction version is serialized unsigned, this should convert to its unsigned equivalent.
         tx = CTransaction()
-        tx.nVersion = -0x80000000
+        tx.nVersion = 0x80000000
         rawtx = tx.serialize().hex()
         decrawtx = self.nodes[0].decoderawtransaction(rawtx)
         assert_equal(decrawtx['version'], 0x80000000)
@@ -477,6 +477,20 @@ class RawTransactionsTest(BitcoinTestFramework):
         decrawtx = self.nodes[0].decoderawtransaction(rawtx)
         assert_equal(decrawtx['version'], 0x7fffffff)
 
+        # Test the minimum transaction version number that fits in an unsigned 32-bit integer.
+        tx = CTransaction()
+        tx.nVersion = 0
+        rawtx = tx.serialize().hex()
+        decrawtx = self.nodes[0].decoderawtransaction(rawtx)
+        assert_equal(decrawtx['version'], 0)
+
+        # Test the maximum transaction version number that fits in an unsigned 32-bit integer.
+        tx = CTransaction()
+        tx.nVersion = 0xffffffff
+        rawtx = tx.serialize().hex()
+        decrawtx = self.nodes[0].decoderawtransaction(rawtx)
+        assert_equal(decrawtx['version'], 0xffffffff)
+
     def raw_multisig_transaction_legacy_tests(self):
         self.log.info("Test raw multisig transactions (legacy)")
         # The traditional multisig workflow does not work with descriptor wallets so these are legacy only.

test/functional/test_framework/messages.py

@@ -582,7 +582,7 @@ class CTransaction:
             self.wit = copy.deepcopy(tx.wit)
 
     def deserialize(self, f):
-        self.nVersion = int.from_bytes(f.read(4), "little", signed=True)
+        self.nVersion = int.from_bytes(f.read(4), "little")
         self.vin = deser_vector(f, CTxIn)
         flags = 0
         if len(self.vin) == 0:
@@ -605,7 +605,7 @@ class CTransaction:
 
     def serialize_without_witness(self):
         r = b""
-        r += self.nVersion.to_bytes(4, "little", signed=True)
+        r += self.nVersion.to_bytes(4, "little")
         r += ser_vector(self.vin)
         r += ser_vector(self.vout)
         r += self.nLockTime.to_bytes(4, "little")
@@ -617,7 +617,7 @@ class CTransaction:
         if not self.wit.is_null():
             flags |= 1
         r = b""
-        r += self.nVersion.to_bytes(4, "little", signed=True)
+        r += self.nVersion.to_bytes(4, "little")
         if flags:
             dummy = []
             r += ser_vector(dummy)

test/functional/test_framework/script.py

@@ -738,7 +738,7 @@ def SegwitV0SignatureMsg(script, txTo, inIdx, hashtype, amount):
         hashOutputs = uint256_from_str(hash256(serialize_outputs))
 
     ss = bytes()
-    ss += txTo.nVersion.to_bytes(4, "little", signed=True)
+    ss += txTo.nVersion.to_bytes(4, "little")
     ss += ser_uint256(hashPrevouts)
     ss += ser_uint256(hashSequence)
     ss += txTo.vin[inIdx].prevout.serialize()
@@ -817,7 +817,7 @@ def TaprootSignatureMsg(txTo, spent_utxos, hash_type, input_index = 0, scriptpat
     in_type = hash_type & SIGHASH_ANYONECANPAY
     spk = spent_utxos[input_index].scriptPubKey
     ss = bytes([0, hash_type]) # epoch, hash_type
-    ss += txTo.nVersion.to_bytes(4, "little", signed=True)
+    ss += txTo.nVersion.to_bytes(4, "little")
     ss += txTo.nLockTime.to_bytes(4, "little")
     if in_type != SIGHASH_ANYONECANPAY:
         ss += BIP341_sha_prevouts(txTo)