routing_table.h

// Copyright (c) 2014-2026 Savoir-faire Linux Inc.
// SPDX-License-Identifier: MIT
#pragma once
 
#include "node.h"
 
namespace dht {
 
static constexpr unsigned TARGET_NODES {8};
namespace net {
class NetworkEngine;
}
 
struct Bucket
{
    Bucket()
        : cached()
    {}
    Bucket(sa_family_t af, const InfoHash& f = {}, time_point t = time_point::min())
        : af(af)
        , first(f)
        , time(t)
        , cached()
    {}
    sa_family_t af {0};
    InfoHash first {};
    time_point time {time_point::min()}; /* time of last reply in this bucket */
    std::list<Sp<Node>> nodes {};
    Sp<Node> cached; /* the address of a likely candidate */

    Sp<Node> randomNode(std::mt19937_64& rd);
 
    void sendCachedPing(net::NetworkEngine& ne);
    void connectivityChanged()
    {
        time = time_point::min();
        for (auto& node : nodes)
            node->setTime(time_point::min());
    }
};
 
class RoutingTable : public std::list<Bucket>
{
public:
    using std::list<Bucket>::list;
 
    time_point grow_time {time_point::min()};
    bool is_client {false};
 
    InfoHash middle(const RoutingTable::const_iterator&) const;
 
    std::vector<Sp<Node>> findClosestNodes(const InfoHash id, time_point now, size_t count = TARGET_NODES) const;
 
    RoutingTable::iterator findBucket(const InfoHash& id);
    RoutingTable::const_iterator findBucket(const InfoHash& id) const;

    inline bool contains(const RoutingTable::const_iterator& bucket, const InfoHash& id) const
    {
        return InfoHash::cmp(bucket->first, id) <= 0
               && (std::next(bucket) == end() || InfoHash::cmp(id, std::next(bucket)->first) < 0);
    }

    inline bool isEmpty() const { return empty() || (size() == 1 && front().nodes.empty()); }
 
    void connectivityChanged(const time_point& now)
    {
        grow_time = now;
        for (auto& b : *this)
            b.connectivityChanged();
    }
 
    bool onNewNode(
        const Sp<Node>& node, int comfirm, const time_point& now, const InfoHash& myid, net::NetworkEngine& ne);

    InfoHash randomId(const RoutingTable::const_iterator& bucket, std::mt19937_64& rd) const;
 
    unsigned depth(const RoutingTable::const_iterator& bucket) const;

    bool split(const RoutingTable::iterator& b);
};
 
} // namespace dht