transaction.py: (txin guess) fix some false positive matches of p2sh-segwit (#4336)

lib/tests/test_transaction.py

@@ -290,6 +290,11 @@ class TestTransaction(unittest.TestCase):
         txid = 'c659729a7fea5071361c2c1a68551ca2bf77679b27086cc415adeeb03852e369'
         self._run_naive_tests_on_tx(raw_tx, txid)
 
+    def test_txid_regression_issue_4333(self):
+        raw_tx = '0100000001a300499298b3f03200c05d1a15aa111a33c769aff6fb355c6bf52ebdb58ca37100000000171600756161616161616161616161616161616161616151fdffffff01c40900000000000017a914001975d5f07f3391674416c1fcd67fd511d257ff871bc71300'
+        txid = '9b9f39e314662a7433aadaa5c94a2f1e24c7e7bf55fc9e1f83abd72be933eb95'
+        self._run_naive_tests_on_tx(raw_tx, txid)
+
 
 # these transactions are from Bitcoin Core unit tests --->
 # https://github.com/bitcoin/bitcoin/blob/11376b5583a283772c82f6d32d0007cdbf5b8ef0/src/test/data/tx_valid.json

lib/transaction.py

@@ -384,6 +384,15 @@ def parse_scriptSig(d, _bytes):
                 bh2u(_bytes))
 
 
+def _revise_txin_type_guess_for_txin(txin):
+    _type = txin.get('type', 'unknown')
+    # fix incorrect guess of p2sh-segwit
+    we_guessed_segwit_input_type = Transaction.is_segwit_inputtype(_type)
+    has_zero_witness = txin.get('witness', '00') in ('00', None)
+    if we_guessed_segwit_input_type and has_zero_witness:
+        txin['type'] = 'unknown'
+
+
 def parse_redeemScript_multisig(redeem_script: bytes):
     dec2 = [ x for x in script_GetOp(redeem_script) ]
     try:
@@ -567,6 +576,9 @@ def deserialize(raw):
             txin = d['inputs'][i]
             parse_witness(vds, txin)
     d['lockTime'] = vds.read_uint32()
+    for i in range(n_vin):
+        txin = d['inputs'][i]
+        _revise_txin_type_guess_for_txin(txin)
     return d