Add more OP_RETURN mempool acceptance functional tests

Credit: Sjors Provoost and Antoine Poinsot

Author: petertodd

test/functional/mempool_accept.py

@@ -9,6 +9,7 @@
 import math
 
 from test_framework.test_framework import BitcoinTestFramework
+from test_framework.blocktools import MAX_STANDARD_TX_WEIGHT
 from test_framework.messages import (
     MAX_BIP125_RBF_SEQUENCE,
     COIN,
@@ -327,6 +328,54 @@ def run_test(self):
             rawtxs=[tx.serialize().hex()],
         )
 
+        # OP_RETURN followed by non-push
+        tx = tx_from_hex(raw_tx_reference)
+        tx.vout[0].scriptPubKey = CScript([OP_RETURN, OP_HASH160])
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': False, 'reject-reason': 'scriptpubkey'}],
+            rawtxs=[tx.serialize().hex()],
+        )
+
+        # Multiple OP_RETURN and more than 83 bytes, even if over MAX_SCRIPT_ELEMENT_SIZE
+        # are standard since v30
+        tx = tx_from_hex(raw_tx_reference)
+        tx.vout.append(CTxOut(0, CScript([OP_RETURN, b'\xff'])))
+        tx.vout.append(CTxOut(0, CScript([OP_RETURN, b'\xff' * 50000])))
+
+        self.check_mempool_result(
+            result_expected=[{'txid': tx.rehash(), 'allowed': True, 'vsize': tx.get_vsize(), 'fees': {'base': Decimal('0.05')}}],
+            rawtxs=[tx.serialize().hex()],
+            maxfeerate=0
+        )
+
+        self.log.info("A transaction with several OP_RETURN outputs.")
+        tx = tx_from_hex(raw_tx_reference)
+        op_return_count = 42
+        tx.vout[0].nValue = int(tx.vout[0].nValue / op_return_count)
+        tx.vout[0].scriptPubKey = CScript([OP_RETURN, b'\xff'])
+        tx.vout = [tx.vout[0]] * op_return_count
+        self.check_mempool_result(
+            result_expected=[{"txid": tx.rehash(), "allowed": True, "vsize": tx.get_vsize(), "fees": {"base": Decimal("0.05000026")}}],
+            rawtxs=[tx.serialize().hex()],
+        )
+
+        self.log.info("A transaction with an OP_RETURN output that bumps into the max standardness tx size.")
+        tx = tx_from_hex(raw_tx_reference)
+        tx.vout[0].scriptPubKey = CScript([OP_RETURN])
+        data_len = int(MAX_STANDARD_TX_WEIGHT / 4) - tx.get_vsize() - 5 - 4  # -5 for PUSHDATA4 and -4 for script size
+        tx.vout[0].scriptPubKey = CScript([OP_RETURN, b"\xff" * (data_len)])
+        assert_equal(tx.get_vsize(), int(MAX_STANDARD_TX_WEIGHT / 4))
+        self.check_mempool_result(
+            result_expected=[{"txid": tx.rehash(), "allowed": True, "vsize": tx.get_vsize(), "fees": {"base": Decimal("0.1") - Decimal("0.05")}}],
+            rawtxs=[tx.serialize().hex()],
+        )
+        tx.vout[0].scriptPubKey = CScript([OP_RETURN, b"\xff" * (data_len + 1)])
+        assert_greater_than(tx.get_vsize(), int(MAX_STANDARD_TX_WEIGHT / 4))
+        self.check_mempool_result(
+            result_expected=[{"txid": tx.rehash(), "allowed": False, "reject-reason": "tx-size"}],
+            rawtxs=[tx.serialize().hex()],
+        )
+
         self.log.info('A timelocked transaction')
         tx = tx_from_hex(raw_tx_reference)
         tx.vin[0].nSequence -= 1  # Should be non-max, so locktime is not ignored