1  #!/usr/bin/env python3
  2  # Copyright (c) 2022 The Bitcoin Core developers
  3  # Distributed under the MIT software license, see the accompanying
  4  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  5  """Test initial headers download
  6  
  7  Test that we only try to initially sync headers from one peer (until our chain
  8  is close to caught up), and that each block announcement results in only one
  9  additional peer receiving a getheaders message.
 10  """
 11  
 12  from test_framework.test_framework import BitcoinTestFramework
 13  from test_framework.messages import (
 14      CInv,
 15      MSG_BLOCK,
 16      msg_headers,
 17      msg_inv,
 18  )
 19  from test_framework.p2p import (
 20      p2p_lock,
 21      P2PInterface,
 22  )
 23  from test_framework.util import (
 24      assert_equal,
 25  )
 26  import random
 27  
 28  class HeadersSyncTest(BitcoinTestFramework):
 29      def set_test_params(self):
 30          self.setup_clean_chain = True
 31          self.num_nodes = 1
 32  
 33      def announce_random_block(self, peers):
 34          new_block_announcement = msg_inv(inv=[CInv(MSG_BLOCK, random.randrange(1<<256))])
 35          for p in peers:
 36              p.send_and_ping(new_block_announcement)
 37  
 38      def run_test(self):
 39          self.log.info("Adding a peer to node0")
 40          peer1 = self.nodes[0].add_p2p_connection(P2PInterface())
 41          best_block_hash = int(self.nodes[0].getbestblockhash(), 16)
 42  
 43          # Wait for peer1 to receive a getheaders
 44          peer1.wait_for_getheaders(block_hash=best_block_hash)
 45          # An empty reply will clear the outstanding getheaders request,
 46          # allowing additional getheaders requests to be sent to this peer in
 47          # the future.
 48          peer1.send_without_ping(msg_headers())
 49  
 50          self.log.info("Connecting two more peers to node0")
 51          # Connect 2 more peers; they should not receive a getheaders yet
 52          peer2 = self.nodes[0].add_p2p_connection(P2PInterface())
 53          peer3 = self.nodes[0].add_p2p_connection(P2PInterface())
 54  
 55          all_peers = [peer1, peer2, peer3]
 56  
 57          self.log.info("Verify that peer2 and peer3 don't receive a getheaders after connecting")
 58          for p in all_peers:
 59              p.sync_with_ping()
 60          with p2p_lock:
 61              assert "getheaders" not in peer2.last_message
 62              assert "getheaders" not in peer3.last_message
 63  
 64          self.log.info("Have all peers announce a new block")
 65          self.announce_random_block(all_peers)
 66  
 67          self.log.info("Check that peer1 receives a getheaders in response")
 68          peer1.wait_for_getheaders(block_hash=best_block_hash)
 69          peer1.send_without_ping(msg_headers()) # Send empty response, see above
 70  
 71          self.log.info("Check that exactly 1 of {peer2, peer3} received a getheaders in response")
 72          count = 0
 73          peer_receiving_getheaders = None
 74          for p in [peer2, peer3]:
 75              with p2p_lock:
 76                  if "getheaders" in p.last_message:
 77                      count += 1
 78                      peer_receiving_getheaders = p
 79                      p.send_without_ping(msg_headers()) # Send empty response, see above
 80  
 81          assert_equal(count, 1)
 82  
 83          self.log.info("Announce another new block, from all peers")
 84          self.announce_random_block(all_peers)
 85  
 86          self.log.info("Check that peer1 receives a getheaders in response")
 87          peer1.wait_for_getheaders(block_hash=best_block_hash)
 88  
 89          self.log.info("Check that the remaining peer received a getheaders as well")
 90          expected_peer = peer2
 91          if peer2 == peer_receiving_getheaders:
 92              expected_peer = peer3
 93  
 94          expected_peer.wait_for_getheaders(block_hash=best_block_hash)
 95  
 96          self.log.info("Success!")
 97  
 98  if __name__ == '__main__':
 99      HeadersSyncTest(__file__).main()
100