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  
 42          # Wait for peer1 to receive a getheaders
 43          peer1.wait_for_getheaders()
 44          # An empty reply will clear the outstanding getheaders request,
 45          # allowing additional getheaders requests to be sent to this peer in
 46          # the future.
 47          peer1.send_message(msg_headers())
 48  
 49          self.log.info("Connecting two more peers to node0")
 50          # Connect 2 more peers; they should not receive a getheaders yet
 51          peer2 = self.nodes[0].add_p2p_connection(P2PInterface())
 52          peer3 = self.nodes[0].add_p2p_connection(P2PInterface())
 53  
 54          all_peers = [peer1, peer2, peer3]
 55  
 56          self.log.info("Verify that peer2 and peer3 don't receive a getheaders after connecting")
 57          for p in all_peers:
 58              p.sync_with_ping()
 59          with p2p_lock:
 60              assert "getheaders" not in peer2.last_message
 61              assert "getheaders" not in peer3.last_message
 62  
 63          with p2p_lock:
 64              peer1.last_message.pop("getheaders", None)
 65  
 66          self.log.info("Have all peers announce a new block")
 67          self.announce_random_block(all_peers)
 68  
 69          self.log.info("Check that peer1 receives a getheaders in response")
 70          peer1.wait_for_getheaders()
 71          peer1.send_message(msg_headers()) # Send empty response, see above
 72          with p2p_lock:
 73              peer1.last_message.pop("getheaders", None)
 74  
 75          self.log.info("Check that exactly 1 of {peer2, peer3} received a getheaders in response")
 76          count = 0
 77          peer_receiving_getheaders = None
 78          for p in [peer2, peer3]:
 79              with p2p_lock:
 80                  if "getheaders" in p.last_message:
 81                      count += 1
 82                      peer_receiving_getheaders = p
 83                      p.last_message.pop("getheaders", None)
 84                      p.send_message(msg_headers()) # Send empty response, see above
 85  
 86          assert_equal(count, 1)
 87  
 88          self.log.info("Announce another new block, from all peers")
 89          self.announce_random_block(all_peers)
 90  
 91          self.log.info("Check that peer1 receives a getheaders in response")
 92          peer1.wait_for_getheaders()
 93  
 94          self.log.info("Check that the remaining peer received a getheaders as well")
 95          expected_peer = peer2
 96          if peer2 == peer_receiving_getheaders:
 97              expected_peer = peer3
 98  
 99          expected_peer.wait_for_getheaders()
100  
101          self.log.info("Success!")
102  
103  if __name__ == '__main__':
104      HeadersSyncTest().main()
105