Add script manipulation tools for use in mininode testing framework

script.py is modified from the code in python-bitcoinlib, and provides tools
for manipulating and creating CScript objects.

bignum.py is a dependency for script.py

script_test.py is an example test that uses the script tools for running a test
that compares the behavior of two nodes, in a comptool- style test, for each of
the test cases in the bitcoin unit test script files, script_valid.json and
script_invalid.json.  (This test is very slow to run, but is a proof of concept
for how we can write tests to compare consensus-critical behavior between
different versions of bitcoind.)

bipdersig-p2p.py is another example test in the comptool framework, which tests
deployment of BIP DERSIG for a single node.  It uses the script.py tools for
manipulating signatures to be non-DER compliant.

Author: sdaftuar

qa/rpc-tests/bignum.py

@@ -0,0 +1,102 @@
+#
+#
+# bignum.py
+#
+# This file is copied from python-bitcoinlib.
+#
+# Distributed under the MIT/X11 software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+
+"""Bignum routines"""
+
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+import struct
+
+
+# generic big endian MPI format
+
+def bn_bytes(v, have_ext=False):
+    ext = 0
+    if have_ext:
+        ext = 1
+    return ((v.bit_length()+7)//8) + ext
+
+def bn2bin(v):
+    s = bytearray()
+    i = bn_bytes(v)
+    while i > 0:
+        s.append((v >> ((i-1) * 8)) & 0xff)
+        i -= 1
+    return s
+
+def bin2bn(s):
+    l = 0
+    for ch in s:
+        l = (l << 8) | ch
+    return l
+
+def bn2mpi(v):
+    have_ext = False
+    if v.bit_length() > 0:
+        have_ext = (v.bit_length() & 0x07) == 0
+
+    neg = False
+    if v < 0:
+        neg = True
+        v = -v
+
+    s = struct.pack(b">I", bn_bytes(v, have_ext))
+    ext = bytearray()
+    if have_ext:
+        ext.append(0)
+    v_bin = bn2bin(v)
+    if neg:
+        if have_ext:
+            ext[0] |= 0x80
+        else:
+            v_bin[0] |= 0x80
+    return s + ext + v_bin
+
+def mpi2bn(s):
+    if len(s) < 4:
+        return None
+    s_size = bytes(s[:4])
+    v_len = struct.unpack(b">I", s_size)[0]
+    if len(s) != (v_len + 4):
+        return None
+    if v_len == 0:
+        return 0
+
+    v_str = bytearray(s[4:])
+    neg = False
+    i = v_str[0]
+    if i & 0x80:
+        neg = True
+        i &= ~0x80
+        v_str[0] = i
+
+    v = bin2bn(v_str)
+
+    if neg:
+        return -v
+    return v
+
+# bitcoin-specific little endian format, with implicit size
+def mpi2vch(s):
+    r = s[4:]           # strip size
+    r = r[::-1]         # reverse string, converting BE->LE
+    return r
+
+def bn2vch(v):
+    return bytes(mpi2vch(bn2mpi(v)))
+
+def vch2mpi(s):
+    r = struct.pack(b">I", len(s))   # size
+    r += s[::-1]            # reverse string, converting LE->BE
+    return r
+
+def vch2bn(s):
+    return mpi2bn(vch2mpi(s))
+

qa/rpc-tests/bipdersig-p2p.py

@@ -0,0 +1,183 @@
+#!/usr/bin/env python2
+#
+# Distributed under the MIT/X11 software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+#
+
+from test_framework import ComparisonTestFramework
+from util import *
+from mininode import CTransaction, NetworkThread
+from blocktools import create_coinbase, create_block
+from binascii import hexlify, unhexlify
+import cStringIO
+from comptool import TestInstance, TestManager
+from script import CScript
+import time
+
+# A canonical signature consists of: 
+# <30> <total len> <02> <len R> <R> <02> <len S> <S> <hashtype>
+def unDERify(tx):
+    '''
+    Make the signature in vin 0 of a tx non-DER-compliant,
+    by adding padding after the S-value.
+    '''
+    scriptSig = CScript(tx.vin[0].scriptSig)
+    newscript = []
+    for i in scriptSig:
+        if (len(newscript) == 0):
+            newscript.append(i[0:-1] + '\0' + i[-1])
+        else:
+            newscript.append(i)
+    tx.vin[0].scriptSig = CScript(newscript)
+    
+'''
+This test is meant to exercise BIP66 (DER SIG).
+Connect to a single node.
+Mine 2 (version 2) blocks (save the coinbases for later).
+Generate 98 more version 2 blocks, verify the node accepts.
+Mine 749 version 3 blocks, verify the node accepts.
+Check that the new DERSIG rules are not enforced on the 750th version 3 block.
+Check that the new DERSIG rules are enforced on the 751st version 3 block.
+Mine 199 new version blocks.
+Mine 1 old-version block.
+Mine 1 new version block.
+Mine 1 old version block, see that the node rejects.
+'''
+            
+class BIP66Test(ComparisonTestFramework):
+
+    def __init__(self):
+        self.num_nodes = 1
+
+    def setup_network(self):
+        # Must set the blockversion for this test
+        self.nodes = start_nodes(1, self.options.tmpdir, 
+                                 extra_args=[['-debug', '-whitelist=127.0.0.1', '-blockversion=2']],
+                                 binary=[self.options.testbinary])
+
+    def run_test(self):
+        test = TestManager(self, self.options.tmpdir)
+        test.add_all_connections(self.nodes)
+        NetworkThread().start() # Start up network handling in another thread
+        test.run()
+
+    def create_transaction(self, node, coinbase, to_address, amount):
+        from_txid = node.getblock(coinbase)['tx'][0]
+        inputs = [{ "txid" : from_txid, "vout" : 0}]
+        outputs = { to_address : amount }
+        rawtx = node.createrawtransaction(inputs, outputs)
+        signresult = node.signrawtransaction(rawtx)
+        tx = CTransaction()
+        f = cStringIO.StringIO(unhexlify(signresult['hex']))
+        tx.deserialize(f)
+        return tx
+
+    def get_tests(self):
+
+        self.coinbase_blocks = self.nodes[0].generate(2)
+        self.tip = int ("0x" + self.nodes[0].getbestblockhash() + "L", 0)
+        self.nodeaddress = self.nodes[0].getnewaddress()
+        self.last_block_time = time.time()
+
+        ''' 98 more version 2 blocks '''
+        test_blocks = []
+        for i in xrange(98):
+            block = create_block(self.tip, create_coinbase(2), self.last_block_time + 1)
+            block.nVersion = 2
+            block.rehash()
+            block.solve()
+            test_blocks.append([block, True])
+            self.last_block_time += 1
+            self.tip = block.sha256
+        yield TestInstance(test_blocks, sync_every_block=False)
+
+        ''' Mine 749 version 3 blocks '''
+        test_blocks = []
+        for i in xrange(749):
+            block = create_block(self.tip, create_coinbase(2), self.last_block_time + 1)
+            block.nVersion = 3
+            block.rehash()
+            block.solve()
+            test_blocks.append([block, True])
+            self.last_block_time += 1
+            self.tip = block.sha256
+        yield TestInstance(test_blocks, sync_every_block=False)
+
+        ''' 
+        Check that the new DERSIG rules are not enforced in the 750th
+        version 3 block.
+        '''
+        spendtx = self.create_transaction(self.nodes[0],
+                self.coinbase_blocks[0], self.nodeaddress, 1.0)
+        unDERify(spendtx)
+        spendtx.rehash()
+
+        block = create_block(self.tip, create_coinbase(2), self.last_block_time + 1)
+        block.nVersion = 3
+        block.vtx.append(spendtx)
+        block.hashMerkleRoot = block.calc_merkle_root()
+        block.rehash()
+        block.solve()
+
+        self.last_block_time += 1
+        self.tip = block.sha256
+        yield TestInstance([[block, True]])
+
+        ''' 
+        Check that the new DERSIG rules are enforced in the 751st version 3
+        block.
+        '''
+        spendtx = self.create_transaction(self.nodes[0],
+                self.coinbase_blocks[1], self.nodeaddress, 1.0)
+        unDERify(spendtx)
+        spendtx.rehash()
+
+        block = create_block(self.tip, create_coinbase(1), self.last_block_time + 1)
+        block.nVersion = 3
+        block.vtx.append(spendtx)
+        block.hashMerkleRoot = block.calc_merkle_root()
+        block.rehash()
+        block.solve()
+        self.last_block_time += 1
+        yield TestInstance([[block, False]])
+
+        ''' Mine 199 new version blocks on last valid tip '''
+        test_blocks = []
+        for i in xrange(199):
+            block = create_block(self.tip, create_coinbase(1), self.last_block_time + 1)
+            block.nVersion = 3
+            block.rehash()
+            block.solve()
+            test_blocks.append([block, True])
+            self.last_block_time += 1
+            self.tip = block.sha256
+        yield TestInstance(test_blocks, sync_every_block=False)
+
+        ''' Mine 1 old version block '''
+        block = create_block(self.tip, create_coinbase(1), self.last_block_time + 1)
+        block.nVersion = 2
+        block.rehash()
+        block.solve()
+        self.last_block_time += 1
+        self.tip = block.sha256
+        yield TestInstance([[block, True]])
+
+        ''' Mine 1 new version block '''
+        block = create_block(self.tip, create_coinbase(1), self.last_block_time + 1)
+        block.nVersion = 3
+        block.rehash()
+        block.solve()
+        self.last_block_time += 1
+        self.tip = block.sha256
+        yield TestInstance([[block, True]])
+
+        ''' Mine 1 old version block, should be invalid '''
+        block = create_block(self.tip, create_coinbase(1), self.last_block_time + 1)
+        block.nVersion = 2
+        block.rehash()
+        block.solve()
+        self.last_block_time += 1
+        yield TestInstance([[block, False]])
+
+if __name__ == '__main__':
+    BIP66Test().main()