test: add invalid tx templates for use in functional tests

Add templates for easily constructing different kinds of invalid
transactions and use them in feature_block and p2p_invalid_tx.

test/functional/data/invalid_txs.py

@@ -0,0 +1,180 @@
+#!/usr/bin/env python3
+# Copyright (c) 2015-2018 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""
+Templates for constructing various sorts of invalid transactions.
+
+These templates (or an iterator over all of them) can be reused in different
+contexts to test using a number of invalid transaction types.
+
+Hopefully this makes it easier to get coverage of a full variety of tx
+validation checks through different interfaces (AcceptBlock, AcceptToMemPool,
+etc.) without repeating ourselves.
+
+Invalid tx cases not covered here can be found by running:
+
+    $ diff \
+      <(grep -IREho "bad-txns[a-zA-Z-]+" src | sort -u) \
+      <(grep -IEho "bad-txns[a-zA-Z-]+" test/functional/data/invalid_txs.py | sort -u)
+
+"""
+import abc
+
+from test_framework.messages import CTransaction, CTxIn, CTxOut, COutPoint
+from test_framework import script as sc
+from test_framework.blocktools import create_tx_with_script, MAX_BLOCK_SIGOPS
+
+basic_p2sh = sc.CScript([sc.OP_HASH160, sc.hash160(sc.CScript([sc.OP_0])), sc.OP_EQUAL])
+
+
+class BadTxTemplate:
+    """Allows simple construction of a certain kind of invalid tx. Base class to be subclassed."""
+    __metaclass__ = abc.ABCMeta
+
+    # The expected error code given by bitcoind upon submission of the tx.
+    reject_reason = ""
+
+    # Only specified if it differs from mempool acceptance error.
+    block_reject_reason = ""
+
+    # Do we expect to be disconnected after submitting this tx?
+    expect_disconnect = False
+
+    # Is this tx considered valid when included in a block, but not for acceptance into
+    # the mempool (i.e. does it violate policy but not consensus)?
+    valid_in_block = False
+
+    def __init__(self, *, spend_tx=None, spend_block=None):
+        self.spend_tx = spend_block.vtx[0] if spend_block else spend_tx
+        self.spend_avail = sum(o.nValue for o in self.spend_tx.vout)
+        self.valid_txin = CTxIn(COutPoint(self.spend_tx.sha256, 0), b"", 0xffffffff)
+
+    @abc.abstractmethod
+    def get_tx(self, *args, **kwargs):
+        """Return a CTransaction that is invalid per the subclass."""
+        pass
+
+
+class OutputMissing(BadTxTemplate):
+    reject_reason = "bad-txns-vout-empty"
+    expect_disconnect = False
+
+    def get_tx(self):
+        tx = CTransaction()
+        tx.vin.append(self.valid_txin)
+        tx.calc_sha256()
+        return tx
+
+
+class InputMissing(BadTxTemplate):
+    reject_reason = "bad-txns-vin-empty"
+    expect_disconnect = False
+
+    def get_tx(self):
+        tx = CTransaction()
+        tx.vout.append(CTxOut(0, sc.CScript([sc.OP_TRUE] * 100)))
+        tx.calc_sha256()
+        return tx
+
+
+class SizeTooSmall(BadTxTemplate):
+    reject_reason = "tx-size-small"
+    expect_disconnect = False
+    valid_in_block = True
+
+    def get_tx(self):
+        tx = CTransaction()
+        tx.vin.append(self.valid_txin)
+        tx.vout.append(CTxOut(0, sc.CScript([sc.OP_TRUE])))
+        tx.calc_sha256()
+        return tx
+
+
+class BadInputOutpointIndex(BadTxTemplate):
+    # Won't be rejected - nonexistent outpoint index is treated as an orphan since the coins
+    # database can't distinguish between spent outpoints and outpoints which never existed.
+    reject_reason = None
+    expect_disconnect = False
+
+    def get_tx(self):
+        num_indices = len(self.spend_tx.vin)
+        bad_idx = num_indices + 100
+
+        tx = CTransaction()
+        tx.vin.append(CTxIn(COutPoint(self.spend_tx.sha256, bad_idx), b"", 0xffffffff))
+        tx.vout.append(CTxOut(0, basic_p2sh))
+        tx.calc_sha256()
+        return tx
+
+
+class DuplicateInput(BadTxTemplate):
+    reject_reason = 'bad-txns-inputs-duplicate'
+    expect_disconnect = True
+
+    def get_tx(self):
+        tx = CTransaction()
+        tx.vin.append(self.valid_txin)
+        tx.vin.append(self.valid_txin)
+        tx.vout.append(CTxOut(1, basic_p2sh))
+        tx.calc_sha256()
+        return tx
+
+
+class NonexistentInput(BadTxTemplate):
+    reject_reason = None  # Added as an orphan tx.
+    expect_disconnect = False
+
+    def get_tx(self):
+        tx = CTransaction()
+        tx.vin.append(CTxIn(COutPoint(self.spend_tx.sha256 + 1, 0), b"", 0xffffffff))
+        tx.vin.append(self.valid_txin)
+        tx.vout.append(CTxOut(1, basic_p2sh))
+        tx.calc_sha256()
+        return tx
+
+
+class SpendTooMuch(BadTxTemplate):
+    reject_reason = 'bad-txns-in-belowout'
+    expect_disconnect = True
+
+    def get_tx(self):
+        return create_tx_with_script(
+            self.spend_tx, 0, script_pub_key=basic_p2sh, amount=(self.spend_avail + 1))
+
+
+class SpendNegative(BadTxTemplate):
+    reject_reason = 'bad-txns-vout-negative'
+    expect_disconnect = True
+
+    def get_tx(self):
+        return create_tx_with_script(self.spend_tx, 0, amount=-1)
+
+
+class InvalidOPIFConstruction(BadTxTemplate):
+    reject_reason = "mandatory-script-verify-flag-failed (Invalid OP_IF construction)"
+    expect_disconnect = True
+    valid_in_block = True
+
+    def get_tx(self):
+        return create_tx_with_script(
+            self.spend_tx, 0, script_sig=b'\x64' * 35,
+            amount=(self.spend_avail // 2))
+
+
+class TooManySigops(BadTxTemplate):
+    reject_reason = "bad-txns-too-many-sigops"
+    block_reject_reason = "bad-blk-sigops, out-of-bounds SigOpCount"
+    expect_disconnect = False
+
+    def get_tx(self):
+        lotsa_checksigs = sc.CScript([sc.OP_CHECKSIG] * (MAX_BLOCK_SIGOPS))
+        return create_tx_with_script(
+            self.spend_tx, 0,
+            script_pub_key=lotsa_checksigs,
+            amount=1)
+
+
+def iter_all_templates():
+    """Iterate through all bad transaction template types."""
+    return BadTxTemplate.__subclasses__()