test: Add anchor mempool acceptance test

Author: instagibbs

test/functional/mempool_accept.py

@@ -37,6 +37,7 @@
     keys_to_multisig_script,
     MIN_PADDING,
     MIN_STANDARD_TX_NONWITNESS_SIZE,
+    PAY_TO_ANCHOR,
     script_to_p2sh_script,
     script_to_p2wsh_script,
 )
@@ -389,6 +390,56 @@ def run_test(self):
             maxfeerate=0,
         )
 
+        self.log.info('OP_1 <0x4e73> is able to be created and spent')
+        anchor_value = 10000
+        create_anchor_tx = self.wallet.send_to(from_node=node, scriptPubKey=PAY_TO_ANCHOR, amount=anchor_value)
+        self.generate(node, 1)
+
+        # First spend has non-empty witness, will be rejected to prevent third party wtxid malleability
+        anchor_nonempty_wit_spend = CTransaction()
+        anchor_nonempty_wit_spend.vin.append(CTxIn(COutPoint(int(create_anchor_tx["txid"], 16), create_anchor_tx["sent_vout"]), b""))
+        anchor_nonempty_wit_spend.vout.append(CTxOut(anchor_value - int(fee*COIN), script_to_p2wsh_script(CScript([OP_TRUE]))))
+        anchor_nonempty_wit_spend.wit.vtxinwit.append(CTxInWitness())
+        anchor_nonempty_wit_spend.wit.vtxinwit[0].scriptWitness.stack.append(b"f")
+        anchor_nonempty_wit_spend.rehash()
+
+        self.check_mempool_result(
+            result_expected=[{'txid': anchor_nonempty_wit_spend.rehash(), 'allowed': False, 'reject-reason': 'bad-witness-nonstandard'}],
+            rawtxs=[anchor_nonempty_wit_spend.serialize().hex()],
+            maxfeerate=0,
+        )
+
+        # Clear witness stuffing
+        anchor_spend = anchor_nonempty_wit_spend
+        anchor_spend.wit.vtxinwit[0].scriptWitness.stack = []
+        anchor_spend.rehash()
+
+        self.check_mempool_result(
+            result_expected=[{'txid': anchor_spend.rehash(), 'allowed': True, 'vsize': anchor_spend.get_vsize(), 'fees': { 'base': Decimal('0.00000700')}}],
+            rawtxs=[anchor_spend.serialize().hex()],
+            maxfeerate=0,
+        )
+
+        self.log.info('But cannot be spent if nested sh()')
+        nested_anchor_tx = self.wallet.create_self_transfer(sequence=SEQUENCE_FINAL)['tx']
+        nested_anchor_tx.vout[0].scriptPubKey = script_to_p2sh_script(PAY_TO_ANCHOR)
+        nested_anchor_tx.rehash()
+        self.generateblock(node, self.wallet.get_address(), [nested_anchor_tx.serialize().hex()])
+
+        nested_anchor_spend = CTransaction()
+        nested_anchor_spend.vin.append(CTxIn(COutPoint(nested_anchor_tx.sha256, 0), b""))
+        nested_anchor_spend.vin[0].scriptSig = CScript([bytes(PAY_TO_ANCHOR)])
+        nested_anchor_spend.vout.append(CTxOut(nested_anchor_tx.vout[0].nValue - int(fee*COIN), script_to_p2wsh_script(CScript([OP_TRUE]))))
+        nested_anchor_spend.rehash()
+
+        self.check_mempool_result(
+            result_expected=[{'txid': nested_anchor_spend.rehash(), 'allowed': False, 'reject-reason': 'non-mandatory-script-verify-flag (Witness version reserved for soft-fork upgrades)'}],
+            rawtxs=[nested_anchor_spend.serialize().hex()],
+            maxfeerate=0,
+        )
+        # but is consensus-legal
+        self.generateblock(node, self.wallet.get_address(), [nested_anchor_spend.serialize().hex()])
+
         self.log.info('Spending a confirmed bare multisig is okay')
         address = self.wallet.get_address()
         tx = tx_from_hex(raw_tx_reference)

test/functional/test_framework/script_util.py

@@ -8,6 +8,7 @@
 from test_framework.script import (
     CScript,
     OP_0,
+    OP_1,
     OP_15,
     OP_16,
     OP_CHECKMULTISIG,
@@ -42,6 +43,8 @@
 DUMMY_MIN_OP_RETURN_SCRIPT = CScript([OP_RETURN] + ([OP_0] * (MIN_PADDING - 1)))
 assert len(DUMMY_MIN_OP_RETURN_SCRIPT) == MIN_PADDING
 
+PAY_TO_ANCHOR = CScript([OP_1, bytes.fromhex("4e73")])
+
 def key_to_p2pk_script(key):
     key = check_key(key)
     return CScript([key, OP_CHECKSIG])