Add functional test for P2P eviction logic of inbound peers

2 files changed, 130 insertions, 0 deletions

diff --git a/test/functional/p2p_eviction.py b/test/functional/p2p_eviction.py
new file mode 100755
index 0000000000..b2b3a89aab
--- /dev/null
+++ b/test/functional/p2p_eviction.py
@@ -0,0 +1,129 @@
+#!/usr/bin/env python3
+# Copyright (c) 2019 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 node eviction logic
+
+When the number of peers has reached the limit of maximum connections,
+the next connecting inbound peer will trigger the eviction mechanism.
+We cannot currently test the parts of the eviction logic that are based on
+address/netgroup since in the current framework, all peers are connecting from
+the same local address. See Issue #14210 for more info.
+Therefore, this test is limited to the remaining protection criteria.
+"""
+
+import time
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.mininode import P2PInterface, P2PDataStore
+from test_framework.util import assert_equal, wait_until
+from test_framework.blocktools import create_block, create_coinbase
+from test_framework.messages import CTransaction, FromHex, msg_pong, msg_tx
+
+
+class SlowP2PDataStore(P2PDataStore):
+    def on_ping(self, message):
+        time.sleep(0.1)
+        self.send_message(msg_pong(message.nonce))
+
+class SlowP2PInterface(P2PInterface):
+    def on_ping(self, message):
+        time.sleep(0.1)
+        self.send_message(msg_pong(message.nonce))
+
+class P2PEvict(BitcoinTestFramework):
+    def set_test_params(self):
+        self.setup_clean_chain = True
+        self.num_nodes = 1
+        # The choice of maxconnections=32 results in a maximum of 21 inbound connections
+        # (32 - 10 outbound - 1 feeler). 20 inbound peers are protected from eviction:
+        # 4 by netgroup, 4 that sent us blocks, 4 that sent us transactions and 8 via lowest ping time
+        self.extra_args = [['-maxconnections=32']]
+
+    def run_test(self):
+        protected_peers = set()  # peers that we expect to be protected from eviction
+        current_peer = -1
+        node = self.nodes[0]
+        node.generatetoaddress(101, node.get_deterministic_priv_key().address)
+
+        self.log.info("Create 4 peers and protect them from eviction by sending us a block")
+        for _ in range(4):
+            block_peer = node.add_p2p_connection(SlowP2PDataStore())
+            current_peer += 1
+            block_peer.sync_with_ping()
+            best_block = node.getbestblockhash()
+            tip = int(best_block, 16)
+            best_block_time = node.getblock(best_block)['time']
+            block = create_block(tip, create_coinbase(node.getblockcount() + 1), best_block_time + 1)
+            block.solve()
+            block_peer.send_blocks_and_test([block], node, success=True)
+            protected_peers.add(current_peer)
+
+        self.log.info("Create 5 slow-pinging peers, making them eviction candidates")
+        for _ in range(5):
+            node.add_p2p_connection(SlowP2PInterface())
+            current_peer += 1
+
+        self.log.info("Create 4 peers and protect them from eviction by sending us a tx")
+        for i in range(4):
+            txpeer = node.add_p2p_connection(SlowP2PInterface())
+            current_peer += 1
+            txpeer.sync_with_ping()
+
+            prevtx = node.getblock(node.getblockhash(i + 1), 2)['tx'][0]
+            rawtx = node.createrawtransaction(
+                inputs=[{'txid': prevtx['txid'], 'vout': 0}],
+                outputs=[{node.get_deterministic_priv_key().address: 50 - 0.00125}],
+            )
+            sigtx = node.signrawtransactionwithkey(
+                hexstring=rawtx,
+                privkeys=[node.get_deterministic_priv_key().key],
+                prevtxs=[{
+                    'txid': prevtx['txid'],
+                    'vout': 0,
+                    'scriptPubKey': prevtx['vout'][0]['scriptPubKey']['hex'],
+                }],
+            )['hex']
+            txpeer.send_message(msg_tx(FromHex(CTransaction(), sigtx)))
+            protected_peers.add(current_peer)
+
+        self.log.info("Create 8 peers and protect them from eviction by having faster pings")
+        for _ in range(8):
+            fastpeer = node.add_p2p_connection(P2PInterface())
+            current_peer += 1
+            wait_until(lambda: "ping" in fastpeer.last_message, timeout=10)
+
+        # Make sure by asking the node what the actual min pings are
+        peerinfo = node.getpeerinfo()
+        pings = {}
+        for i in range(len(peerinfo)):
+            pings[i] = peerinfo[i]['minping'] if 'minping' in peerinfo[i] else 1000000
+        sorted_pings = sorted(pings.items(), key=lambda x: x[1])
+
+        # Usually the 8 fast peers are protected. In rare case of unreliable pings,
+        # one of the slower peers might have a faster min ping though.
+        for i in range(8):
+            protected_peers.add(sorted_pings[i][0])
+
+        self.log.info("Create peer that triggers the eviction mechanism")
+        node.add_p2p_connection(SlowP2PInterface())
+
+        # One of the non-protected peers must be evicted. We can't be sure which one because
+        # 4 peers are protected via netgroup, which is identical for all peers,
+        # and the eviction mechanism doesn't preserve the order of identical elements.
+        evicted_peers = []
+        for i in range(len(node.p2ps)):
+            if not node.p2ps[i].is_connected:
+                evicted_peers.append(i)
+
+        self.log.info("Test that one peer was evicted")
+        self.log.debug("{} evicted peer: {}".format(len(evicted_peers), set(evicted_peers)))
+        assert_equal(len(evicted_peers), 1)
+
+        self.log.info("Test that no peer expected to be protected was evicted")
+        self.log.debug("{} protected peers: {}".format(len(protected_peers), protected_peers))
+        assert evicted_peers[0] not in protected_peers
+
+if __name__ == '__main__':
+    P2PEvict().main()
diff --git a/test/functional/test_runner.py b/test/functional/test_runner.py
index 7821355e29..2053d91321 100755
--- a/test/functional/test_runner.py
+++ b/test/functional/test_runner.py
@@ -188,6 +188,7 @@ BASE_SCRIPTS = [
     'rpc_preciousblock.py',
     'wallet_importprunedfunds.py',
     'p2p_leak_tx.py',
+    'p2p_eviction.py',
     'rpc_signmessage.py',
     'rpc_generateblock.py',
     'wallet_balance.py',