text: #!/usr/bin/env python3
  # Copyright (c) 2009-2019 The Bitcoin Core developers
  # Copyright (c) 2014-2019 The DigiByte Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  """Test logic for skipping signature validation on old blocks.
  
  Test logic for skipping signature validation on blocks which we've assumed
  valid (https://github.com/digibyte/digibyte/pull/9484)
  
  We build a chain that includes and invalid signature for one of the
  transactions:
  
      0:        genesis block
      1:        block 1 with coinbase transaction output.
      2-101:    bury that block with 100 blocks so the coinbase transaction
                output can be spent
      102:      a block containing a transaction spending the coinbase
                transaction output. The transaction has an invalid signature.
      103-2202: bury the bad block with just over two weeks' worth of blocks
                (2100 blocks)
  
  Start three nodes:
  
      - node0 has no -assumevalid parameter. Try to sync to block 2202. It will
        reject block 102 and only sync as far as block 101
      - node1 has -assumevalid set to the hash of block 102. Try to sync to
        block 2202. node1 will sync all the way to block 2202.
      - node2 has -assumevalid set to the hash of block 102. Try to sync to
        block 200. node2 will reject block 102 since it's assumed valid, but it
        isn't buried by at least two weeks' work.
  """
  import time
  
  from test_framework.blocktools import (create_block, create_coinbase)
  from test_framework.key import CECKey
  from test_framework.messages import (
      CBlockHeader,
      COutPoint,
      CTransaction,
      CTxIn,
      CTxOut,
      msg_block,
      msg_headers
  )
  from test_framework.mininode import P2PInterface
  from test_framework.script import (CScript, OP_TRUE)
  from test_framework.test_framework import DigiByteTestFramework
  from test_framework.util import assert_equal
  
  class BaseNode(P2PInterface):
      def send_header_for_blocks(self, new_blocks):
          headers_message = msg_headers()
          headers_message.headers = [CBlockHeader(b) for b in new_blocks]
          self.send_message(headers_message)
  
  class AssumeValidTest(DigiByteTestFramework):
      def set_test_params(self):
          self.setup_clean_chain = True
          self.num_nodes = 3
  
      def setup_network(self):
          self.add_nodes(3)
          # Start node0. We don't start the other nodes yet since
          # we need to pre-mine a block with an invalid transaction
          # signature so we can pass in the block hash as assumevalid.
          self.start_node(0)
  
      def send_blocks_until_disconnected(self, p2p_conn):
          """Keep sending blocks to the node until we're disconnected."""
          for i in range(len(self.blocks)):
              if not p2p_conn.is_connected:
                  break
              try:
                  p2p_conn.send_message(msg_block(self.blocks[i]))
              except IOError as e:
                  assert not p2p_conn.is_connected
                  break
  
      def assert_blockchain_height(self, node, height):
          """Wait until the blockchain is no longer advancing and verify it's reached the expected height."""
          last_height = node.getblock(node.getbestblockhash())['height']
          timeout = 10
          while True:
              time.sleep(0.25)
              current_height = node.getblock(node.getbestblockhash())['height']
              if current_height != last_height:
                  last_height = current_height
                  if timeout < 0:
                      assert False, "blockchain too short after timeout: %d" % current_height
                  timeout - 0.25
                  continue
              elif current_height > height:
                  assert False, "blockchain too long: %d" % current_height
              elif current_height == height:
                  break
  
      def run_test(self):
          p2p0 = self.nodes[0].add_p2p_connection(BaseNode())
  
          # Build the blockchain
          self.tip = int(self.nodes[0].getbestblockhash(), 16)
          self.block_time = self.nodes[0].getblock(self.nodes[0].getbestblockhash())['time'] + 1
  
          self.blocks = []
  
          # Get a pubkey for the coinbase TXO
          coinbase_key = CECKey()
          coinbase_key.set_secretbytes(b"horsebattery")
          coinbase_pubkey = coinbase_key.get_pubkey()
  
          # Create the first block with a coinbase output to our key
          height = 1
          block = create_block(self.tip, create_coinbase(height, coinbase_pubkey), self.block_time)
          self.blocks.append(block)
          self.block_time += 1
          block.solve()
          # Save the coinbase for later
          self.block1 = block
          self.tip = block.sha256
          height += 1
  
          # Bury the block 100 deep so the coinbase output is spendable
          for i in range(100):
              block = create_block(self.tip, create_coinbase(height), self.block_time)
              block.solve()
              self.blocks.append(block)
              self.tip = block.sha256
              self.block_time += 1
              height += 1
  
          # Create a transaction spending the coinbase output with an invalid (null) signature
          tx = CTransaction()
          tx.vin.append(CTxIn(COutPoint(self.block1.vtx[0].sha256, 0), scriptSig=b""))
          tx.vout.append(CTxOut(49 * 100000000, CScript([OP_TRUE])))
          tx.calc_sha256()
  
          block102 = create_block(self.tip, create_coinbase(height), self.block_time)
          self.block_time += 1
          block102.vtx.extend([tx])
          block102.hashMerkleRoot = block102.calc_merkle_root()
          block102.rehash()
          block102.solve()
          self.blocks.append(block102)
          self.tip = block102.sha256
          self.block_time += 1
          height += 1
  
          # Bury the assumed valid block 2100 deep
          for i in range(2100):
              block = create_block(self.tip, create_coinbase(height), self.block_time)
              block.nVersion = 4
              block.solve()
              self.blocks.append(block)
              self.tip = block.sha256
              self.block_time += 1
              height += 1
  
          self.nodes[0].disconnect_p2ps()
  
          # Start node1 and node2 with assumevalid so they accept a block with a bad signature.
          self.start_node(1, extra_args=["-assumevalid=" + hex(block102.sha256)])
          self.start_node(2, extra_args=["-assumevalid=" + hex(block102.sha256)])
  
          p2p0 = self.nodes[0].add_p2p_connection(BaseNode())
          p2p1 = self.nodes[1].add_p2p_connection(BaseNode())
          p2p2 = self.nodes[2].add_p2p_connection(BaseNode())
  
          # send header lists to all three nodes
          p2p0.send_header_for_blocks(self.blocks[0:2000])
          p2p0.send_header_for_blocks(self.blocks[2000:])
          p2p1.send_header_for_blocks(self.blocks[0:2000])
          p2p1.send_header_for_blocks(self.blocks[2000:])
          p2p2.send_header_for_blocks(self.blocks[0:200])
  
          # Send blocks to node0. Block 102 will be rejected.
          self.send_blocks_until_disconnected(p2p0)
          self.assert_blockchain_height(self.nodes[0], 101)
  
          # Send all blocks to node1. All blocks will be accepted.
          for i in range(2202):
              p2p1.send_message(msg_block(self.blocks[i]))
          # Syncing 2200 blocks can take a while on slow systems. Give it plenty of time to sync.
          p2p1.sync_with_ping(150)
          assert_equal(self.nodes[1].getblock(self.nodes[1].getbestblockhash())['height'], 2202)
  
          # Send blocks to node2. Block 102 will be rejected.
          self.send_blocks_until_disconnected(p2p2)
          self.assert_blockchain_height(self.nodes[2], 101)
  
  if __name__ == '__main__':
      AssumeValidTest().main()
  