READ THE CODE

Inside Bitcoin

The code behind the network, with room to understand it.

Stable release v32.1bitcoin/bitcoin · f0de87f04062 ↗3,020 source files · 47.5 MB stored on the server440 file guides

Release published 2026-10-28 · Snapshot fetched 2026-11-01. Latest stable release at fetch time; development branches and Git history are excluded. Only the selected code window and visible folders load here.

5,248 bytes · SHA-256 9a2bd085831865d9… · View upstream ↗

1#!/usr/bin/env python3
2# Copyright (c) 2019-present 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
6""" Test node eviction logic
7
8When the number of peers has reached the limit of maximum connections,
9the next connecting inbound peer will trigger the eviction mechanism.
10We cannot currently test the parts of the eviction logic that are based on
11address/netgroup since in the current framework, all peers are connecting from
12the same local address. See Issue #14210 for more info.
13Therefore, this test is limited to the remaining protection criteria.
14"""
15import time
16
17from test_framework.blocktools import (
18    create_block,
19)
20from test_framework.messages import (
21    msg_pong,
22    msg_tx,
23)
24from test_framework.p2p import (
25    P2PDataStore,
26    P2PInterface,
27)
28from test_framework.test_framework import BitcoinTestFramework
29from test_framework.util import assert_equal
30from test_framework.wallet import MiniWallet
31
32
33class SlowP2PDataStore(P2PDataStore):
34    def on_ping(self, message):
35        time.sleep(0.1)
36        self.send_without_ping(msg_pong(message.nonce))
37
38
39class SlowP2PInterface(P2PInterface):
40    def on_ping(self, message):
41        time.sleep(0.1)
42        self.send_without_ping(msg_pong(message.nonce))
43
44
45class P2PEvict(BitcoinTestFramework):
46    def set_test_params(self):
47        self.num_nodes = 1
48        # The choice of maxconnections=53 results in a maximum of 21 tx-relaying inbound connections
49        # (53 - 10 outbound - 1 feeler) * 0.5 = 21. The other inbound slots are reserved for block-relay-only
50        # peers that don't play a role in this test.
51        # 20 inbound peers are protected from eviction:
52        # 4 by netgroup, 4 that sent us blocks, 4 that sent us transactions and 8 via lowest ping time
53        self.extra_args = [['-maxconnections=53']]
54
55    def run_test(self):
56        protected_peers = set()  # peers that we expect to be protected from eviction
57        current_peer = -1
58        node = self.nodes[0]
59        self.wallet = MiniWallet(node)
60
61        self.log.info("Create 4 peers and protect them from eviction by sending us a block")
62        for _ in range(4):
63            block_peer = node.add_p2p_connection(SlowP2PDataStore())
64            current_peer += 1
65            block_peer.sync_with_ping()
66            best_block = node.getbestblockhash()
67            tip = int(best_block, 16)
68            best_block_time = node.getblock(best_block)['time']
69            block = create_block(tip, height=node.getblockcount() + 1, ntime=best_block_time + 1)
70            block.solve()
71            block_peer.send_blocks_and_test([block], node, success=True)
72            protected_peers.add(current_peer)
73
74        self.log.info("Create 5 slow-pinging peers, making them eviction candidates")
75        for _ in range(5):
76            node.add_p2p_connection(SlowP2PInterface())
77            current_peer += 1
78
79        self.log.info("Create 4 peers and protect them from eviction by sending us a tx")
80        for i in range(4):
81            txpeer = node.add_p2p_connection(SlowP2PInterface())
82            current_peer += 1
83            txpeer.sync_with_ping()
84
85            tx = self.wallet.create_self_transfer()['tx']
86            txpeer.send_without_ping(msg_tx(tx))
87            protected_peers.add(current_peer)
88
89        self.log.info("Create 8 peers and protect them from eviction by having faster pings")
90        for _ in range(8):
91            fastpeer = node.add_p2p_connection(P2PInterface())
92            current_peer += 1
93            self.wait_until(lambda: "ping" in fastpeer.last_message, timeout=10)
94
95        # Make sure by asking the node what the actual min pings are
96        peerinfo = node.getpeerinfo()
97        pings = {}
98        for i in range(len(peerinfo)):
99            pings[i] = peerinfo[i]['minping'] if 'minping' in peerinfo[i] else 1000000
100        sorted_pings = sorted(pings.items(), key=lambda x: x[1])
101
102        # Usually the 8 fast peers are protected. In rare case of unreliable pings,
103        # one of the slower peers might have a faster min ping though.
104        for i in range(8):
105            protected_peers.add(sorted_pings[i][0])
106
107        self.log.info("Create peer that triggers the eviction mechanism")
108        node.add_p2p_connection(SlowP2PInterface())
109
110        # One of the non-protected peers must be evicted. We can't be sure which one because
111        # 4 peers are protected via netgroup, which is identical for all peers,
112        # and the eviction mechanism doesn't preserve the order of identical elements.
113        evicted_peers = []
114        for i in range(len(node.p2ps)):
115            if not node.p2ps[i].is_connected:
116                evicted_peers.append(i)
117
118        self.log.info("Test that one peer was evicted")
119        self.log.debug("{} evicted peer: {}".format(len(evicted_peers), set(evicted_peers)))
120        assert_equal(len(evicted_peers), 1)
121
122        self.log.info("Test that no peer expected to be protected was evicted")
123        self.log.debug("{} protected peers: {}".format(len(protected_peers), protected_peers))
124        assert evicted_peers[0] not in protected_peers
125
126
127if __name__ == '__main__':
128    P2PEvict(__file__).main()
129

src/wallet/receive.cpp

src/wallet/coinselection.cpp

src/consensus/validation.h

src/primitives/transaction.cpp

src/script/descriptor.cpp

src/bitcoin-cli.cpp

src/rpc/blockchain.cpp

src/rpc/rawtransaction.cpp

src/init.cpp

src/crypto/sha256.cpp

src/consensus/merkle.h

src/consensus/tx_check.h

src/consensus/tx_verify.h

src/policy/feerate.h

src/policy/feerate.cpp

src/primitives/transaction_identifier.h

src/chainparamsbase.h

src/chainparamsbase.cpp

src/util/moneystr.cpp

src/crypto/ripemd160.h

src/crypto/sha1.h

src/crypto/sha512.h

src/crypto/hmac_sha256.h

src/crypto/hmac_sha512.h

src/crypto/hmac_sha256.cpp

src/crypto/hmac_sha512.cpp

src/crypto/hkdf_sha256_32.h

src/crypto/hkdf_sha256_32.cpp

src/support/cleanse.h

src/support/cleanse.cpp

src/crypto/siphash.cpp

src/crypto/muhash.h

src/crypto/chacha20.h

src/crypto/poly1305.h

src/crypto/chacha20poly1305.h

src/crypto/chacha20poly1305.cpp

src/util/chaintype.cpp

src/util/obfuscation.h

src/util/byte_units.h

src/util/overflow.h

src/blockencodings.cpp

src/net_permissions.cpp

src/policy/packages.cpp

src/policy/rbf.cpp

src/policy/truc_policy.cpp

src/policy/ephemeral_policy.cpp

src/policy/settings.cpp

src/policy/policy.cpp

src/node/transaction.cpp

src/node/coin.cpp

src/rpc/client.cpp

src/rpc/external_signer.cpp

src/rpc/request.cpp

src/rpc/server_util.cpp

src/rpc/fees.cpp

src/rpc/output_script.cpp

src/rpc/rawtransaction_util.cpp

src/rpc/rawtransaction_util.h

src/rpc/register.h

src/rpc/request.h

src/rpc/server_util.h

src/rpc/protocol.h

src/rpc/server.h

src/rpc/signmessage.cpp

src/rpc/txoutproof.cpp

src/rpc/util.cpp

src/rpc/util.h

src/wallet/rpc/addresses.cpp

src/wallet/rpc/backup.cpp

src/wallet/rpc/coins.cpp

src/wallet/rpc/encrypt.cpp

src/wallet/rpc/signmessage.cpp

src/wallet/rpc/util.cpp

src/wallet/rpc/util.h

src/wallet/coincontrol.cpp

src/wallet/coincontrol.h

src/wallet/context.cpp

src/wallet/context.h

src/wallet/crypter.cpp

src/wallet/crypter.h

src/wallet/db.cpp

src/wallet/export.cpp

src/wallet/external_signer_scriptpubkeyman.cpp

src/wallet/rpc/spend.cpp

src/wallet/rpc/transactions.cpp

src/wallet/rpc/wallet.cpp

src/wallet/feebumper.cpp

src/wallet/feebumper.h

src/index/base.h

src/index/base.cpp

src/index/txindex.h

src/index/txindex.cpp

src/index/txindex_key.h

src/index/txospenderindex.h

src/index/txospenderindex.cpp

src/index/blockfilterindex.h

src/index/blockfilterindex.cpp

src/index/coinstatsindex.h

src/index/coinstatsindex.cpp

src/index/db_key.h

src/index/disktxpos.h

src/kernel/chain.cpp

src/kernel/chain.h

src/kernel/checks.cpp

src/kernel/checks.h

src/kernel/context.cpp

src/kernel/context.h

src/kernel/cs_main.cpp

src/kernel/cs_main.h

src/kernel/disconnected_transactions.cpp

src/kernel/disconnected_transactions.h

src/kernel/mempool_removal_reason.cpp

src/kernel/mempool_removal_reason.h

src/kernel/coinstats.cpp

src/kernel/coinstats.h

src/kernel/chainparams.cpp

src/kernel/chainparams.h

src/wallet/sqlite.cpp

src/wallet/sqlite.h

src/wallet/transaction.cpp

src/wallet/transaction.h

src/wallet/dump.cpp

src/wallet/dump.h

src/wallet/init.cpp

src/wallet/walletutil.cpp

src/wallet/walletutil.h

src/wallet/wallettool.cpp

src/wallet/wallettool.h

src/wallet/export.h

src/wallet/migrate.cpp

src/wallet/migrate.h

src/wallet/db.h

src/wallet/walletdb.cpp

src/wallet/interfaces.cpp

src/wallet/scriptpubkeyman.cpp

src/wallet/scriptpubkeyman.h

src/kernel/bitcoinkernel.cpp

src/kernel/bitcoinkernel.h

src/kernel/bitcoinkernel_wrapper.h

src/node/chainstate.cpp

src/node/chainstate.h

src/node/blockstorage.cpp

src/node/blockstorage.h

src/node/mempool_persist.cpp

src/node/mempool_persist.h

src/node/utxo_snapshot.cpp

src/node/utxo_snapshot.h

src/node/kernel_notifications.cpp

src/node/kernel_notifications.h

src/node/blockmanager_args.cpp

src/kernel/blockmanager_opts.h

src/util/expected.cpp

src/policy/settings.h

src/util/types.h

src/kernel/messagestartchars.h

src/kernel/warning.h

src/util/exception.h

src/common/license_info.h

src/node/coins_view_args.h

src/node/database_args.h

src/util/batchpriority.h

src/util/ui_change_type.h

src/node/coins_view_args.cpp

src/node/peerman_args.h

src/util/serfloat.h

src/node/blockmanager_args.h

src/node/database_args.cpp

src/util/overloaded.h

src/interfaces/types.h

src/node/chainstatemanager_args.h

src/node/minisketchwrapper.h

src/util/macros.h

src/util/syserror.h

src/common/run_command.h

src/util/bytevectorhash.cpp

src/node/mempool_persist_args.cpp

src/util/exec.h

src/util/rbf.h

src/crypto/hex_base.h

src/node/mempool_persist_args.h

src/interfaces/echo.h

src/util/any.h

src/util/batchpriority.cpp

src/util/threadnames.h

src/node/coin.h

src/node/mempool_args.h

src/util/asmap.h

src/util/bytevectorhash.h

src/node/context.cpp

src/util/insert.h

src/util/readwritefile.h

src/node/peerman_args.cpp

src/node/interface_ui.cpp

src/interfaces/handler.h

src/node/mining_args.h

src/util/hasher.cpp

src/common/init.h

src/kernel/mempool_limits.h

src/common/system.h

src/crypto/sha3.h

src/util/threadinterrupt.cpp

src/node/protocol_version.h

src/util/exception.cpp

src/common/messages.h

src/node/connection_types.cpp

src/util/bip32.h

src/common/license_info.cpp

src/util/stdmutex.h

src/common/run_command.cpp

src/util/check.cpp

src/util/golombrice.h

src/node/types.h

src/node/timeoffsets.h

src/util/readwritefile.cpp

src/util/fastrange.h

src/util/signalinterrupt.h

src/util/task_runner.h

src/util/syserror.cpp

src/common/interfaces.cpp

src/common/types.h

src/util/threadinterrupt.h

src/kernel/chainstatemanager_opts.h

src/node/psbt.h

src/policy/ephemeral_policy.h

src/util/trace.h

src/common/url.cpp

src/kernel/mempool_options.h

src/util/serfloat.cpp

src/kernel/notifications_interface.h

src/node/timeoffsets.cpp

src/node/warnings.cpp

src/util/hash_type.h

src/crypto/hex_base.cpp

src/node/eviction.h

src/util/tokenbucket.h

src/crypto/aes.h

src/common/pcp.h

src/util/feefrac.cpp

src/node/transaction.h

src/util/threadnames.cpp

src/common/signmessage.h

src/util/exec.cpp

src/util/signalinterrupt.cpp

src/clientversion.cpp

src/common/signmessage.cpp

src/compat/assumptions.h

src/compat/byteswap.h

src/deploymentinfo.cpp

src/deploymentinfo.h

src/deploymentstatus.cpp

src/deploymentstatus.h

src/dummywallet.cpp

src/external_signer.h

src/init/bitcoin-gui.cpp

src/init/bitcoin-node.cpp

src/init/bitcoin-qt.cpp

src/init/bitcoin-wallet.cpp

src/init/bitcoind.cpp

src/init/common.h

src/interfaces/init.h

src/interfaces/ipc.h

src/key_io.h

src/logging/categories.h

src/logging/timer.h

src/mapport.h

src/musig.h

src/net_permissions.h

src/netgroup.h

src/netmessagemaker.h

src/node/chainstatemanager_args.cpp

src/node/connection_types.h

src/node/context.h

src/node/interface_ui.h

src/node/mempool_args.cpp

src/node/mining_args.cpp

src/node/minisketchwrapper.cpp

src/node/txreconciliation.h

src/policy/fees/estimator_args.cpp

src/policy/fees/estimator_args.h

src/policy/fees/estimator_man.cpp

src/policy/fees/estimator_man.h

src/policy/packages.h

src/policy/rbf.h

src/policy/truc_policy.h

src/pow.h

src/primitives/block.cpp

src/randomenv.h

src/rest.h

src/script/keyorigin.h

src/script/parsing.cpp

src/script/parsing.h

src/script/script_error.h

src/script/sigcache.cpp

src/script/sigcache.h

src/script/solver.h

src/script/verify_flags.h

src/semaphore_grant.h

src/signet.h

src/span.h

src/support/allocators/secure.h

src/support/allocators/zeroafterfree.h

src/util/tokenpipe.cpp

src/util/translation.h

src/util/vector.h

src/versionbits.h

src/versionbits_impl.h

src/wallet/external_signer_scriptpubkeyman.h

src/wallet/fees.h

src/wallet/load.h

src/wallet/receive.h

src/wallet/rpc/wallet.h

src/wallet/types.h

src/walletinitinterface.h

src/zmq/zmqabstractnotifier.cpp

Independent explanations by MyBitcoinExplorer. Not affiliated with or endorsed by Bitcoin Core. Guides are educational and do not replace the source or its tests.

Bitcoin Core source © its contributors, distributed under the MIT license. Original notices and bundled third-party licenses are retained in the source tree.