Method AttemptToEvictConnection

src/net.cpp:1694–1743

Try to find a connection to evict when the node is full. * Extreme care must be taken to avoid opening the node to attacker * triggered network partitioning. * The strategy used here is to protect a small number of peers * for each of several distinct characteristics which are difficult * to forge. In order to partition a node the attacker must be * simultaneously better at all of

 *   simultaneously better at all of them than honest peers.
 */
bool CConnman::AttemptToEvictConnection()
{
    AssertLockNotHeld(m_nodes_mutex);

    std::vector<NodeEvictionCandidate> vEvictionCandidates;
    {

        LOCK(m_nodes_mutex);
        for (const CNode* node : m_nodes) {
            if (node->fDisconnect)
                continue;
            NodeEvictionCandidate candidate{
                .id = node->GetId(),
                .m_connected = node->m_connected,
                .m_min_ping_time = node->m_min_ping_time,
                .m_last_block_time = node->m_last_block_time,
                .m_last_tx_time = node->m_last_tx_time,
                .fRelevantServices = node->m_has_all_wanted_services,
                .m_relay_txs = node->m_relays_txs.load(),
                .fBloomFilter = node->m_bloom_filter_loaded.load(),
                .nKeyedNetGroup = node->nKeyedNetGroup,
                .prefer_evict = node->m_prefer_evict,
                .m_is_local = node->addr.IsLocal(),
                .m_network = node->ConnectedThroughNetwork(),
                .m_noban = node->HasPermission(NetPermissionFlags::NoBan),
                .m_conn_type = node->m_conn_type,
            };
            vEvictionCandidates.push_back(candidate);
        }
    }
    const std::optional<NodeId> node_id_to_evict = SelectNodeToEvict(std::move(vEvictionCandidates));
    if (!node_id_to_evict) {
        return false;
    }
    LOCK(m_nodes_mutex);
    for (CNode* pnode : m_nodes) {
        if (pnode->GetId() == *node_id_to_evict) {
            LogDebug(BCLog::NET, "selected %s connection for eviction, %s", pnode->ConnectionTypeAsString(), pnode->DisconnectMsg());
            TRACEPOINT(net, evicted_inbound_connection,
                pnode->GetId(),
                pnode->m_addr_name.c_str(),
                pnode->ConnectionTypeAsString().c_str(),
                pnode->ConnectedThroughNetwork(),
                TicksSinceEpoch<std::chrono::seconds>(pnode->m_connected));
            pnode->fDisconnect = true;
            return true;
        }
    }
    return false;
}

void CConnman::AcceptConnection(const ListenSocket& hListenSocket) {
    AssertLockNotHeld(m_nodes_mutex);