Merge #7184: Implement SequenceLocks functions for BIP 68

b043c4b fix sdaftuar's nits again (Alex Morcos)
a51c79b Bug fix to RPC test (Alex Morcos)
da6ad5f Add RPC test exercising BIP68 (mempool only) (Suhas Daftuar)
c6c2f0f Implement SequenceLocks functions (Alex Morcos)

2 files changed, 395 insertions, 0 deletions

diff --git a/qa/rpc-tests/bip68-sequence.py b/qa/rpc-tests/bip68-sequence.py
new file mode 100755
index 0000000000..bd61282fa1
--- /dev/null
+++ b/qa/rpc-tests/bip68-sequence.py
@@ -0,0 +1,387 @@
+#!/usr/bin/env python2
+# Copyright (c) 2014-2015 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#
+# Test BIP68 implementation (mempool only)
+#
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import *
+from test_framework.script import *
+from test_framework.mininode import *
+from test_framework.blocktools import *
+
+COIN = 100000000
+SEQUENCE_LOCKTIME_DISABLE_FLAG = (1<<31)
+SEQUENCE_LOCKTIME_TYPE_FLAG = (1<<22) # this means use time (0 means height)
+SEQUENCE_LOCKTIME_GRANULARITY = 9 # this is a bit-shift
+SEQUENCE_LOCKTIME_MASK = 0x0000ffff
+
+# RPC error for non-BIP68 final transactions
+NOT_FINAL_ERROR = "64: non-BIP68-final"
+
+class BIP68Test(BitcoinTestFramework):
+
+    def setup_network(self):
+        self.nodes = []
+        self.nodes.append(start_node(0, self.options.tmpdir, ["-debug", "-blockprioritysize=0"]))
+        self.is_network_split = False
+        self.relayfee = self.nodes[0].getnetworkinfo()["relayfee"]
+
+    def run_test(self):
+        # Generate some coins
+        self.nodes[0].generate(110)
+
+        print "Running test disable flag"
+        self.test_disable_flag()
+
+        print "Running test sequence-lock-confirmed-inputs"
+        self.test_sequence_lock_confirmed_inputs()
+
+        print "Running test sequence-lock-unconfirmed-inputs"
+        self.test_sequence_lock_unconfirmed_inputs()
+
+        # This test needs to change when BIP68 becomes consensus
+        print "Running test BIP68 not consensus"
+        self.test_bip68_not_consensus()
+
+        print "Passed\n"
+
+    # Test that BIP68 is not in effect if tx version is 1, or if
+    # the first sequence bit is set.
+    def test_disable_flag(self):
+        # Create some unconfirmed inputs
+        new_addr = self.nodes[0].getnewaddress()
+        self.nodes[0].sendtoaddress(new_addr, 2) # send 2 BTC
+
+        utxos = self.nodes[0].listunspent(0, 0)
+        assert(len(utxos) > 0)
+
+        utxo = utxos[0]
+
+        tx1 = CTransaction()
+        value = satoshi_round(utxo["amount"] - self.relayfee)*COIN
+
+        # Check that the disable flag disables relative locktime.
+        # If sequence locks were used, this would require 1 block for the
+        # input to mature.
+        sequence_value = SEQUENCE_LOCKTIME_DISABLE_FLAG | 1
+        tx1.vin = [CTxIn(COutPoint(int(utxo["txid"], 16), utxo["vout"]), nSequence=sequence_value)] 
+        tx1.vout = [CTxOut(value, CScript([b'a']))]
+
+        tx1_signed = self.nodes[0].signrawtransaction(ToHex(tx1))["hex"]
+        tx1_id = self.nodes[0].sendrawtransaction(tx1_signed)
+        tx1_id = int(tx1_id, 16)
+
+        # This transaction will enable sequence-locks, so this transaction should
+        # fail
+        tx2 = CTransaction()
+        tx2.nVersion = 2
+        sequence_value = sequence_value & 0x7fffffff
+        tx2.vin = [CTxIn(COutPoint(tx1_id, 0), nSequence=sequence_value)]
+        tx2.vout = [CTxOut(int(value-self.relayfee*COIN), CScript([b'a']))]
+        tx2.rehash()
+
+        try:
+            self.nodes[0].sendrawtransaction(ToHex(tx2))
+        except JSONRPCException as exp:
+            assert_equal(exp.error["message"], NOT_FINAL_ERROR)
+        else:
+            assert(False)
+
+        # Setting the version back down to 1 should disable the sequence lock,
+        # so this should be accepted.
+        tx2.nVersion = 1
+
+        self.nodes[0].sendrawtransaction(ToHex(tx2))
+
+    # Calculate the median time past of a prior block ("confirmations" before
+    # the current tip).
+    def get_median_time_past(self, confirmations):
+        block_hash = self.nodes[0].getblockhash(self.nodes[0].getblockcount()-confirmations)
+        return self.nodes[0].getblockheader(block_hash)["mediantime"]
+
+    # Test that sequence locks are respected for transactions spending confirmed inputs.
+    def test_sequence_lock_confirmed_inputs(self):
+        # Create lots of confirmed utxos, and use them to generate lots of random
+        # transactions.
+        max_outputs = 50
+        addresses = []
+        while len(addresses) < max_outputs:
+            addresses.append(self.nodes[0].getnewaddress())
+        while len(self.nodes[0].listunspent()) < 200:
+            import random
+            random.shuffle(addresses)
+            num_outputs = random.randint(1, max_outputs)
+            outputs = {}
+            for i in xrange(num_outputs):
+                outputs[addresses[i]] = random.randint(1, 20)*0.01
+            self.nodes[0].sendmany("", outputs)
+            self.nodes[0].generate(1)
+
+        utxos = self.nodes[0].listunspent()
+
+        # Try creating a lot of random transactions.
+        # Each time, choose a random number of inputs, and randomly set
+        # some of those inputs to be sequence locked (and randomly choose
+        # between height/time locking). Small random chance of making the locks
+        # all pass.
+        for i in xrange(400):
+            # Randomly choose up to 10 inputs
+            num_inputs = random.randint(1, 10)
+            random.shuffle(utxos)
+
+            # Track whether any sequence locks used should fail
+            should_pass = True
+            
+            # Track whether this transaction was built with sequence locks
+            using_sequence_locks = False
+
+            tx = CTransaction()
+            tx.nVersion = 2
+            value = 0
+            for j in xrange(num_inputs):
+                sequence_value = 0xfffffffe # this disables sequence locks
+
+                # 50% chance we enable sequence locks
+                if random.randint(0,1):
+                    using_sequence_locks = True
+
+                    # 10% of the time, make the input sequence value pass
+                    input_will_pass = (random.randint(1,10) == 1)
+                    sequence_value = utxos[j]["confirmations"]
+                    if not input_will_pass:
+                        sequence_value += 1
+                        should_pass = False
+
+                    # Figure out what the median-time-past was for the confirmed input
+                    # Note that if an input has N confirmations, we're going back N blocks
+                    # from the tip so that we're looking up MTP of the block
+                    # PRIOR to the one the input appears in, as per the BIP68 spec.
+                    orig_time = self.get_median_time_past(utxos[j]["confirmations"])
+                    cur_time = self.get_median_time_past(0) # MTP of the tip
+
+                    # can only timelock this input if it's not too old -- otherwise use height
+                    can_time_lock = True
+                    if ((cur_time - orig_time) >> SEQUENCE_LOCKTIME_GRANULARITY) >= SEQUENCE_LOCKTIME_MASK:
+                        can_time_lock = False
+
+                    # if time-lockable, then 50% chance we make this a time lock
+                    if random.randint(0,1) and can_time_lock:
+                        # Find first time-lock value that fails, or latest one that succeeds
+                        time_delta = sequence_value << SEQUENCE_LOCKTIME_GRANULARITY
+                        if input_will_pass and time_delta > cur_time - orig_time:
+                            sequence_value = ((cur_time - orig_time) >> SEQUENCE_LOCKTIME_GRANULARITY)
+                        elif (not input_will_pass and time_delta <= cur_time - orig_time):
+                            sequence_value = ((cur_time - orig_time) >> SEQUENCE_LOCKTIME_GRANULARITY)+1
+                        sequence_value |= SEQUENCE_LOCKTIME_TYPE_FLAG
+                tx.vin.append(CTxIn(COutPoint(int(utxos[j]["txid"], 16), utxos[j]["vout"]), nSequence=sequence_value))
+                value += utxos[j]["amount"]*COIN
+            # Overestimate the size of the tx - signatures should be less than 120 bytes, and leave 50 for the output
+            tx_size = len(ToHex(tx))/2 + 120*num_inputs + 50
+            tx.vout.append(CTxOut(value-self.relayfee*tx_size*COIN/1000, CScript([b'a'])))
+            rawtx = self.nodes[0].signrawtransaction(ToHex(tx))["hex"]
+
+            try:
+                self.nodes[0].sendrawtransaction(rawtx)
+            except JSONRPCException as exp:
+                assert(not should_pass and using_sequence_locks)
+                assert_equal(exp.error["message"], NOT_FINAL_ERROR)
+            else:
+                assert(should_pass or not using_sequence_locks)
+                # Recalculate utxos if we successfully sent the transaction
+                utxos = self.nodes[0].listunspent()
+
+    # Test that sequence locks on unconfirmed inputs must have nSequence
+    # height or time of 0 to be accepted.
+    # Then test that BIP68-invalid transactions are removed from the mempool
+    # after a reorg.
+    def test_sequence_lock_unconfirmed_inputs(self):
+        # Store height so we can easily reset the chain at the end of the test
+        cur_height = self.nodes[0].getblockcount()
+
+        # Create a mempool tx.
+        txid = self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), 2)
+        tx1 = FromHex(CTransaction(), self.nodes[0].getrawtransaction(txid))
+        tx1.rehash()
+
+        # Anyone-can-spend mempool tx.
+        # Sequence lock of 0 should pass.
+        tx2 = CTransaction()
+        tx2.nVersion = 2
+        tx2.vin = [CTxIn(COutPoint(tx1.sha256, 0), nSequence=0)]
+        tx2.vout = [CTxOut(int(tx1.vout[0].nValue - self.relayfee*COIN), CScript([b'a']))]
+        tx2_raw = self.nodes[0].signrawtransaction(ToHex(tx2))["hex"]
+        tx2 = FromHex(tx2, tx2_raw)
+        tx2.rehash()
+
+        self.nodes[0].sendrawtransaction(tx2_raw)
+
+        # Create a spend of the 0th output of orig_tx with a sequence lock
+        # of 1, and test what happens when submitting.
+        # orig_tx.vout[0] must be an anyone-can-spend output
+        def test_nonzero_locks(orig_tx, node, relayfee, use_height_lock):
+            sequence_value = 1
+            if not use_height_lock:
+                sequence_value |= SEQUENCE_LOCKTIME_TYPE_FLAG
+
+            tx = CTransaction()
+            tx.nVersion = 2
+            tx.vin = [CTxIn(COutPoint(orig_tx.sha256, 0), nSequence=sequence_value)]
+            tx.vout = [CTxOut(int(orig_tx.vout[0].nValue - relayfee*COIN), CScript([b'a']))]
+            tx.rehash()
+
+            try:
+                node.sendrawtransaction(ToHex(tx))
+            except JSONRPCException as exp:
+                assert_equal(exp.error["message"], NOT_FINAL_ERROR)
+                assert(orig_tx.hash in node.getrawmempool())
+            else:
+                # orig_tx must not be in mempool
+                assert(orig_tx.hash not in node.getrawmempool())
+            return tx
+
+        test_nonzero_locks(tx2, self.nodes[0], self.relayfee, use_height_lock=True)
+        test_nonzero_locks(tx2, self.nodes[0], self.relayfee, use_height_lock=False)
+
+        # Now mine some blocks, but make sure tx2 doesn't get mined.
+        # Use prioritisetransaction to lower the effective feerate to 0
+        self.nodes[0].prioritisetransaction(tx2.hash, -1e15, int(-self.relayfee*COIN))
+        cur_time = int(time.time())
+        for i in xrange(10):
+            self.nodes[0].setmocktime(cur_time + 600)
+            self.nodes[0].generate(1)
+            cur_time += 600
+
+        assert(tx2.hash in self.nodes[0].getrawmempool())
+
+        test_nonzero_locks(tx2, self.nodes[0], self.relayfee, use_height_lock=True)
+        test_nonzero_locks(tx2, self.nodes[0], self.relayfee, use_height_lock=False)
+
+        # Mine tx2, and then try again
+        self.nodes[0].prioritisetransaction(tx2.hash, 1e15, int(self.relayfee*COIN))
+
+        # Advance the time on the node so that we can test timelocks
+        self.nodes[0].setmocktime(cur_time+600)
+        self.nodes[0].generate(1)
+        assert(tx2.hash not in self.nodes[0].getrawmempool())
+
+        # Now that tx2 is not in the mempool, a sequence locked spend should
+        # succeed
+        tx3 = test_nonzero_locks(tx2, self.nodes[0], self.relayfee, use_height_lock=False)
+        assert(tx3.hash in self.nodes[0].getrawmempool())
+
+        self.nodes[0].generate(1)
+        assert(tx3.hash not in self.nodes[0].getrawmempool())
+
+        # One more test, this time using height locks
+        tx4 = test_nonzero_locks(tx3, self.nodes[0], self.relayfee, use_height_lock=True)
+        assert(tx4.hash in self.nodes[0].getrawmempool())
+
+        # Now try combining confirmed and unconfirmed inputs
+        tx5 = test_nonzero_locks(tx4, self.nodes[0], self.relayfee, use_height_lock=True)
+        assert(tx5.hash not in self.nodes[0].getrawmempool())
+
+        utxos = self.nodes[0].listunspent()
+        tx5.vin.append(CTxIn(COutPoint(int(utxos[0]["txid"], 16), utxos[0]["vout"]), nSequence=1))
+        tx5.vout[0].nValue += int(utxos[0]["amount"]*COIN)
+        raw_tx5 = self.nodes[0].signrawtransaction(ToHex(tx5))["hex"]
+
+        try:
+            self.nodes[0].sendrawtransaction(raw_tx5)
+        except JSONRPCException as exp:
+            assert_equal(exp.error["message"], NOT_FINAL_ERROR)
+        else:
+            assert(False)
+
+        # Test mempool-BIP68 consistency after reorg
+        #
+        # State of the transactions in the last blocks:
+        # ... -> [ tx2 ] ->  [ tx3 ]
+        #         tip-1        tip
+        # And currently tx4 is in the mempool.
+        #
+        # If we invalidate the tip, tx3 should get added to the mempool, causing
+        # tx4 to be removed (fails sequence-lock).
+        self.nodes[0].invalidateblock(self.nodes[0].getbestblockhash())
+        assert(tx4.hash not in self.nodes[0].getrawmempool())
+        assert(tx3.hash in self.nodes[0].getrawmempool())
+
+        # Now mine 2 empty blocks to reorg out the current tip (labeled tip-1 in
+        # diagram above).
+        # This would cause tx2 to be added back to the mempool, which in turn causes
+        # tx3 to be removed.
+        tip = int(self.nodes[0].getblockhash(self.nodes[0].getblockcount()-1), 16)
+        height = self.nodes[0].getblockcount()
+        for i in xrange(2):
+            block = create_block(tip, create_coinbase(height), cur_time)
+            block.nVersion = 3
+            block.rehash()
+            block.solve()
+            tip = block.sha256
+            height += 1
+            self.nodes[0].submitblock(ToHex(block))
+            cur_time += 1
+
+        mempool = self.nodes[0].getrawmempool()
+        assert(tx3.hash not in mempool)
+        assert(tx2.hash in mempool)
+
+        # Reset the chain and get rid of the mocktimed-blocks
+        self.nodes[0].setmocktime(0)
+        self.nodes[0].invalidateblock(self.nodes[0].getblockhash(cur_height+1))
+        self.nodes[0].generate(10)
+
+    # Make sure that BIP68 isn't being used to validate blocks.
+    def test_bip68_not_consensus(self):
+        txid = self.nodes[0].sendtoaddress(self.nodes[0].getnewaddress(), 2)
+
+        tx1 = FromHex(CTransaction(), self.nodes[0].getrawtransaction(txid))
+        tx1.rehash()
+
+        # Make an anyone-can-spend transaction
+        tx2 = CTransaction()
+        tx2.nVersion = 1
+        tx2.vin = [CTxIn(COutPoint(tx1.sha256, 0), nSequence=0)]
+        tx2.vout = [CTxOut(int(tx1.vout[0].nValue - self.relayfee*COIN), CScript([b'a']))]
+
+        # sign tx2
+        tx2_raw = self.nodes[0].signrawtransaction(ToHex(tx2))["hex"]
+        tx2 = FromHex(tx2, tx2_raw)
+        tx2.rehash()
+
+        self.nodes[0].sendrawtransaction(ToHex(tx2))
+        
+        # Now make an invalid spend of tx2 according to BIP68
+        sequence_value = 100 # 100 block relative locktime
+
+        tx3 = CTransaction()
+        tx3.nVersion = 2
+        tx3.vin = [CTxIn(COutPoint(tx2.sha256, 0), nSequence=sequence_value)]
+        tx3.vout = [CTxOut(int(tx2.vout[0].nValue - self.relayfee*COIN), CScript([b'a']))]
+        tx3.rehash()
+
+        try:
+            self.nodes[0].sendrawtransaction(ToHex(tx3))
+        except JSONRPCException as exp:
+            assert_equal(exp.error["message"], NOT_FINAL_ERROR)
+        else:
+            assert(False)
+
+        # make a block that violates bip68; ensure that the tip updates
+        tip = int(self.nodes[0].getbestblockhash(), 16)
+        block = create_block(tip, create_coinbase(self.nodes[0].getblockcount()+1))
+        block.nVersion = 3
+        block.vtx.extend([tx1, tx2, tx3])
+        block.hashMerkleRoot = block.calc_merkle_root()
+        block.rehash()
+        block.solve()
+
+        self.nodes[0].submitblock(ToHex(block))
+        assert_equal(self.nodes[0].getbestblockhash(), block.hash)
+
+
+if __name__ == '__main__':
+    BIP68Test().main()
diff --git a/qa/rpc-tests/test_framework/mininode.py b/qa/rpc-tests/test_framework/mininode.py
index 2135570b8c..81bb439cea 100755
--- a/qa/rpc-tests/test_framework/mininode.py
+++ b/qa/rpc-tests/test_framework/mininode.py
@@ -231,6 +231,14 @@ def ser_int_vector(l):
         r += struct.pack("<i", i)
     return r
 
+# Deserialize from a hex string representation (eg from RPC)
+def FromHex(obj, hex_string):
+    obj.deserialize(cStringIO.StringIO(binascii.unhexlify(hex_string)))
+    return obj
+
+# Convert a binary-serializable object to hex (eg for submission via RPC)
+def ToHex(obj):
+    return binascii.hexlify(obj.serialize()).decode('utf-8')
 
 # Objects that map to bitcoind objects, which can be serialized/deserialized