text: #!/usr/bin/env python3
  # Copyright (c) 2016 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  
  from test_framework.mininode import *
  from test_framework.test_framework import ElectrumTestFramework
  from test_framework.util import *
  import time
  from test_framework.blocktools import create_block, create_coinbase
  
  '''
  Test version bits' warning system.
  
  Generate chains with block versions that appear to be signalling unknown
  soft-forks, and test that warning alerts are generated.
  '''
  
  VB_PERIOD = 144 # versionbits period length for regtest
  VB_THRESHOLD = 108 # versionbits activation threshold for regtest
  VB_TOP_BITS = 0x20000000
  VB_UNKNOWN_BIT = 27 # Choose a bit unassigned to any deployment
  
  # TestNode: bare-bones "peer".  Used mostly as a conduit for a test to sending
  # p2p messages to a node, generating the messages in the main testing logic.
  class TestNode(NodeConnCB):
      def __init__(self):
          NodeConnCB.__init__(self)
          self.connection = None
          self.ping_counter = 1
          self.last_pong = msg_pong()
  
      def add_connection(self, conn):
          self.connection = conn
  
      def on_inv(self, conn, message):
          pass
  
      # Wrapper for the NodeConn's send_message function
      def send_message(self, message):
          self.connection.send_message(message)
  
      def on_pong(self, conn, message):
          self.last_pong = message
  
      # Sync up with the node after delivery of a block
      def sync_with_ping(self, timeout=30):
          self.connection.send_message(msg_ping(nonce=self.ping_counter))
          received_pong = False
          sleep_time = 0.05
          while not received_pong and timeout > 0:
              time.sleep(sleep_time)
              timeout -= sleep_time
              with mininode_lock:
                  if self.last_pong.nonce == self.ping_counter:
                      received_pong = True
          self.ping_counter += 1
          return received_pong
  
  
  class VersionBitsWarningTest(ElectrumTestFramework):
      def __init__(self):
          super().__init__()
          self.setup_clean_chain = True
          self.num_nodes = 1
  
      def setup_network(self):
          self.nodes = []
          self.alert_filename = os.path.join(self.options.tmpdir, "alert.txt")
          # Open and close to create zero-length file
          with open(self.alert_filename, 'w') as f:
              pass
          self.node_options = ["-debug", "-logtimemicros=1", "-alertnotify=echo %s >> \"" + self.alert_filename + "\""]
          self.nodes.append(start_node(0, self.options.tmpdir, self.node_options))
  
          import re
          self.vb_pattern = re.compile("^Warning.*versionbit")
  
      # Send numblocks blocks via peer with nVersionToUse set.
      def send_blocks_with_version(self, peer, numblocks, nVersionToUse):
          tip = self.nodes[0].getbestblockhash()
          height = self.nodes[0].getblockcount()
          block_time = self.nodes[0].getblockheader(tip)["time"]+1
          tip = int(tip, 16)
  
          for i in range(numblocks):
              block = create_block(tip, create_coinbase(height+1), block_time)
              block.nVersion = nVersionToUse
              block.solve()
              peer.send_message(msg_block(block))
              block_time += 1
              height += 1
              tip = block.sha256
          peer.sync_with_ping()
  
      def test_versionbits_in_alert_file(self):
          with open(self.alert_filename, 'r') as f:
              alert_text = f.read()
          assert(self.vb_pattern.match(alert_text))
  
      def run_test(self):
          # Setup the p2p connection and start up the network thread.
          test_node = TestNode()
  
          connections = []
          connections.append(NodeConn('127.0.0.1', p2p_port(0), self.nodes[0], test_node))
          test_node.add_connection(connections[0])
  
          NetworkThread().start() # Start up network handling in another thread
  
          # Test logic begins here
          test_node.wait_for_verack()
  
          # 1. Have the node mine one period worth of blocks
          self.nodes[0].generate(VB_PERIOD)
  
          # 2. Now build one period of blocks on the tip, with < VB_THRESHOLD
          # blocks signaling some unknown bit.
          nVersion = VB_TOP_BITS | (1<<VB_UNKNOWN_BIT)
          self.send_blocks_with_version(test_node, VB_THRESHOLD-1, nVersion)
  
          # Fill rest of period with regular version blocks
          self.nodes[0].generate(VB_PERIOD - VB_THRESHOLD + 1)
          # Check that we're not getting any versionbit-related errors in
          # getinfo()
          assert(not self.vb_pattern.match(self.nodes[0].getinfo()["errors"]))
  
          # 3. Now build one period of blocks with >= VB_THRESHOLD blocks signaling
          # some unknown bit
          self.send_blocks_with_version(test_node, VB_THRESHOLD, nVersion)
          self.nodes[0].generate(VB_PERIOD - VB_THRESHOLD)
          # Might not get a versionbits-related alert yet, as we should
          # have gotten a different alert due to more than 51/100 blocks
          # being of unexpected version.
          # Check that getinfo() shows some kind of error.
          assert(len(self.nodes[0].getinfo()["errors"]) != 0)
  
          # Mine a period worth of expected blocks so the generic block-version warning
          # is cleared, and restart the node. This should move the versionbit state
          # to ACTIVE.
          self.nodes[0].generate(VB_PERIOD)
          stop_node(self.nodes[0], 0)
          wait_electrumds()
          # Empty out the alert file
          with open(self.alert_filename, 'w') as f:
              pass
          self.nodes[0] = start_node(0, self.options.tmpdir, ["-debug", "-logtimemicros=1", "-alertnotify=echo %s >> \"" + self.alert_filename + "\""])
  
          # Connecting one block should be enough to generate an error.
          self.nodes[0].generate(1)
          assert(len(self.nodes[0].getinfo()["errors"]) != 0)
          stop_node(self.nodes[0], 0)
          wait_electrumds()
          self.test_versionbits_in_alert_file()
  
          # Test framework expects the node to still be running...
          self.nodes[0] = start_node(0, self.options.tmpdir, ["-debug", "-logtimemicros=1", "-alertnotify=echo %s >> \"" + self.alert_filename + "\""])
  
  
  if __name__ == '__main__':
      VersionBitsWarningTest().main()
  