dht.h

/*
 *  Copyright (C) 2014-2022 Savoir-faire Linux Inc.
 *  Authors: Adrien Béraud <adrien.beraud@savoirfairelinux.com>
 *           Simon Désaulniers <simon.desaulniers@savoirfairelinux.com>
 *           Sébastien Blin <sebastien.blin@savoirfairelinux.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program. If not, see <https://www.gnu.org/licenses/>.
 */

#pragma once

#include "infohash.h"
#include "value.h"
#include "utils.h"
#include "network_engine.h"
#include "scheduler.h"
#include "routing_table.h"
#include "callbacks.h"
#include "dht_interface.h"

#include <string>
#include <array>
#include <vector>
#include <map>
#include <functional>
#include <memory>

#ifdef _WIN32
#include <iso646.h>
#endif

namespace dht {

namespace net {
struct Request;
} /* namespace net */

struct Storage;
struct ValueStorage;
class StorageBucket;
struct Listener;
struct LocalListener;

class OPENDHT_PUBLIC Dht final : public DhtInterface {
public:
    Dht(std::unique_ptr<net::DatagramSocket>&& sock, const Config& config, const Sp<Logger>& l = {});

    Dht(std::unique_ptr<net::DatagramSocket>&& sock, const Config& config, const Logger& l = {})
        : Dht(std::move(sock), config, std::make_shared<Logger>(l)) {}

    virtual ~Dht();

    inline const InfoHash& getNodeId() const override { return myid; }

    NodeStatus updateStatus(sa_family_t af) override;

    NodeStatus getStatus(sa_family_t af) const override {
        return dht(af).status;
    }

    NodeStatus getStatus() const override {
        return std::max(getStatus(AF_INET), getStatus(AF_INET6));
    }

    net::DatagramSocket* getSocket() const override { return network_engine.getSocket(); };

    void shutdown(ShutdownCallback cb, bool stop = false) override;

    bool isRunning(sa_family_t af = 0) const override;

    virtual void registerType(const ValueType& type) override {
        types.registerType(type);
    }
    const ValueType& getType(ValueType::Id type_id) const override {
        return types.getType(type_id);
    }

    void addBootstrap(const std::string& host, const std::string& service) override {
        bootstrap_nodes.emplace_back(host, service);
        startBootstrap();
    }

    void clearBootstrap() override {
        bootstrap_nodes.clear();
    }

    void insertNode(const InfoHash& id, const SockAddr&) override;
    void insertNode(const NodeExport& n) override {
        insertNode(n.id, SockAddr(n.ss, n.sslen));
    }

    void pingNode(SockAddr, DoneCallbackSimple&& cb={}) override;

    time_point periodic(const uint8_t *buf, size_t buflen, SockAddr, const time_point& now) override;
    time_point periodic(const uint8_t *buf, size_t buflen, const sockaddr* from, socklen_t fromlen, const time_point& now) override {
        return periodic(buf, buflen, SockAddr(from, fromlen), now);
    }

    virtual void get(const InfoHash& key, GetCallback cb, DoneCallback donecb={}, Value::Filter&& f={}, Where&& w = {}) override;
    virtual void get(const InfoHash& key, GetCallback cb, DoneCallbackSimple donecb={}, Value::Filter&& f={}, Where&& w = {}) override {
        get(key, cb, bindDoneCb(donecb), std::forward<Value::Filter>(f), std::forward<Where>(w));
    }
    virtual void get(const InfoHash& key, GetCallbackSimple cb, DoneCallback donecb={}, Value::Filter&& f={}, Where&& w = {}) override {
        get(key, bindGetCb(cb), donecb, std::forward<Value::Filter>(f), std::forward<Where>(w));
    }
    virtual void get(const InfoHash& key, GetCallbackSimple cb, DoneCallbackSimple donecb, Value::Filter&& f={}, Where&& w = {}) override {
        get(key, bindGetCb(cb), bindDoneCb(donecb), std::forward<Value::Filter>(f), std::forward<Where>(w));
    }
    virtual void query(const InfoHash& key, QueryCallback cb, DoneCallback done_cb = {}, Query&& q = {}) override;
    virtual void query(const InfoHash& key, QueryCallback cb, DoneCallbackSimple done_cb = {}, Query&& q = {}) override {
        query(key, cb, bindDoneCb(done_cb), std::forward<Query>(q));
    }

    std::vector<Sp<Value>> getLocal(const InfoHash& key, const Value::Filter& f = {}) const override;

    Sp<Value> getLocalById(const InfoHash& key, Value::Id vid) const override;

    void put(const InfoHash& key,
            Sp<Value>,
            DoneCallback cb=nullptr,
            time_point created=time_point::max(),
            bool permanent = false) override;
    void put(const InfoHash& key,
            const Sp<Value>& v,
            DoneCallbackSimple cb,
            time_point created=time_point::max(),
            bool permanent = false) override
    {
        put(key, v, bindDoneCb(cb), created, permanent);
    }

    void put(const InfoHash& key,
            Value&& v,
            DoneCallback cb=nullptr,
            time_point created=time_point::max(),
            bool permanent = false) override
    {
        put(key, std::make_shared<Value>(std::move(v)), cb, created, permanent);
    }
    void put(const InfoHash& key,
            Value&& v,
            DoneCallbackSimple cb,
            time_point created=time_point::max(),
            bool permanent = false) override
    {
        put(key, std::forward<Value>(v), bindDoneCb(cb), created, permanent);
    }

    std::vector<Sp<Value>> getPut(const InfoHash&) const override;

    Sp<Value> getPut(const InfoHash&, const Value::Id&) const override;

    bool cancelPut(const InfoHash&, const Value::Id&) override;

    size_t listen(const InfoHash&, ValueCallback, Value::Filter={}, Where={}) override;

    size_t listen(const InfoHash& key, GetCallback cb, Value::Filter f={}, Where w={}) override {
        return listen(key, [cb](const std::vector<Sp<Value>>& vals, bool expired){
            if (not expired)
                return cb(vals);
            return true;
        }, std::forward<Value::Filter>(f), std::forward<Where>(w));
    }
    size_t listen(const InfoHash& key, GetCallbackSimple cb, Value::Filter f={}, Where w={}) override {
        return listen(key, bindGetCb(cb), std::forward<Value::Filter>(f), std::forward<Where>(w));
    }

    bool cancelListen(const InfoHash&, size_t token) override;

    void connectivityChanged(sa_family_t) override;
    void connectivityChanged() override {
        reported_addr.clear();
        connectivityChanged(AF_INET);
        connectivityChanged(AF_INET6);
    }

    std::vector<NodeExport> exportNodes() const override;

    std::vector<ValuesExport> exportValues() const override;
    void importValues(const std::vector<ValuesExport>&) override;

    void saveState(const std::string& path) const;
    void loadState(const std::string& path);

    NodeStats getNodesStats(sa_family_t af) const override;

    std::string getStorageLog() const override;
    std::string getStorageLog(const InfoHash&) const override;

    std::string getRoutingTablesLog(sa_family_t) const override;
    std::string getSearchesLog(sa_family_t) const override;
    std::string getSearchLog(const InfoHash&, sa_family_t af = AF_UNSPEC) const override;

    void dumpTables() const override;
    std::vector<unsigned> getNodeMessageStats(bool in = false) override {
        return network_engine.getNodeMessageStats(in);
    }

    void setStorageLimit(size_t limit = DEFAULT_STORAGE_LIMIT) override {
        max_store_size = limit;
    }
    size_t getStorageLimit() const override {
        return max_store_size;
    }

    std::pair<size_t, size_t> getStoreSize() const override {
        return {total_store_size, total_values};
    }

    std::vector<SockAddr> getPublicAddress(sa_family_t family = 0) override;

    void pushNotificationReceived(const std::map<std::string, std::string>&) override {}
    void resubscribe(unsigned) {}

private:

    /* When performing a search, we search for up to SEARCH_NODES closest nodes
       to the destination, and use the additional ones to backtrack if any of
       the target 8 turn out to be dead. */
    static constexpr unsigned SEARCH_NODES {14};

    /* The number of bad nodes is limited in order to help determine
     * presence of connectivity changes. See
     * https://github.com/savoirfairelinux/opendht/issues/137 for details.
     *
     * According to the tables, 25 is a good average value for big networks. If
     * the network is small, normal search expiration process will handle the
     * situation.
     * */
    static constexpr unsigned SEARCH_MAX_BAD_NODES {25};

    /* Concurrent search nodes requested count */
    static constexpr unsigned MAX_REQUESTED_SEARCH_NODES {4};

    /* Number of listening nodes */
    static constexpr unsigned LISTEN_NODES {4};

    /* The maximum number of hashes we're willing to track. */
    static constexpr unsigned MAX_HASHES {1024 * 1024 * 1024};

    /* The maximum number of searches we keep data about. */
    static constexpr unsigned MAX_SEARCHES {1024 * 1024};

    static constexpr std::chrono::minutes MAX_STORAGE_MAINTENANCE_EXPIRE_TIME {10};

    /* The time after which we consider a search to be expirable. */
    static constexpr std::chrono::minutes SEARCH_EXPIRE_TIME {62};

    /* Timeout for listen */
    static constexpr duration LISTEN_EXPIRE_TIME {std::chrono::seconds(30)};
    static constexpr duration LISTEN_EXPIRE_TIME_PUBLIC {std::chrono::minutes(5)};

    static constexpr duration REANNOUNCE_MARGIN {std::chrono::seconds(10)};

    static constexpr std::chrono::seconds BOOTSTRAP_PERIOD {10};

    static constexpr size_t TOKEN_SIZE {32};

    // internal structures
    struct SearchNode;
    struct Get;
    struct Announce;
    struct Search;

    // prevent copy
    Dht(const Dht&) = delete;
    Dht& operator=(const Dht&) = delete;

    std::mt19937_64 rd {crypto::getSeededRandomEngine<std::mt19937_64>()};

    InfoHash myid {};

    uint64_t secret {};
    uint64_t oldsecret {};

    // registred types
    TypeStore types;

    using SearchMap = std::map<InfoHash, Sp<Search>>;
    struct Kad {
        RoutingTable buckets {};
        SearchMap searches {};
        unsigned pending_pings {0};
        NodeStatus status;

        NodeStatus getStatus(time_point now) const;
        NodeStats getNodesStats(time_point now, const InfoHash& myid) const;
    };

    Kad dht4 {};
    Kad dht6 {};

    std::vector<std::pair<std::string,std::string>> bootstrap_nodes {};
    std::chrono::steady_clock::duration bootstrap_period {BOOTSTRAP_PERIOD};
    Sp<Scheduler::Job> bootstrapJob {};

    std::map<InfoHash, Storage> store;
    std::map<SockAddr, StorageBucket, SockAddr::ipCmp> store_quota;
    size_t total_values {0};
    size_t total_store_size {0};
    size_t max_store_keys {MAX_HASHES};
    size_t max_store_size {DEFAULT_STORAGE_LIMIT};

    size_t max_searches {MAX_SEARCHES};
    size_t search_id {0};

    // map a global listen token to IPv4, IPv6 specific listen tokens.
    // 0 is the invalid token.
    std::map<size_t, std::tuple<size_t, size_t, size_t>> listeners {};
    size_t listener_token {1};


    // timing
    Scheduler scheduler;
    Sp<Scheduler::Job> nextNodesConfirmation {};
    Sp<Scheduler::Job> nextStorageMaintenance {};

    net::NetworkEngine network_engine;
    using ReportedAddr = std::pair<unsigned, SockAddr>;
    std::vector<ReportedAddr> reported_addr;

    std::string persistPath;

    // are we a bootstrap node ?
    // note: Any running node can be used as a bootstrap node.
    //       Only nodes running only as bootstrap nodes should
    //       be put in bootstrap mode.
    const bool is_bootstrap {false};
    const bool maintain_storage {false};
    const bool public_stable {false};

    inline const duration& getListenExpiration() const {
        return public_stable ? LISTEN_EXPIRE_TIME_PUBLIC : LISTEN_EXPIRE_TIME;
    }

    void rotateSecrets();

    Blob makeToken(const SockAddr&, bool old) const;
    bool tokenMatch(const Blob& token, const SockAddr&) const;

    void reportedAddr(const SockAddr&);

    // Storage
    void storageAddListener(const InfoHash& id, const Sp<Node>& node, size_t tid, Query&& = {}, int version = 0);
    bool storageStore(const InfoHash& id, const Sp<Value>& value, time_point created, const SockAddr& sa = {}, bool permanent = false);
    bool storageRefresh(const InfoHash& id, Value::Id vid);
    void expireStore();
    void expireStorage(InfoHash h);
    void expireStore(decltype(store)::iterator);

    void storageRemoved(const InfoHash& id, Storage& st, const std::vector<Sp<Value>>& values, size_t totalSize);
    void storageChanged(const InfoHash& id, Storage& st, const Sp<Value>&, bool newValue);
    std::string printStorageLog(const decltype(store)::value_type&) const;

    void dataPersistence(InfoHash id);
    size_t maintainStorage(decltype(store)::value_type&, bool force=false, const DoneCallback& donecb={});

    // Buckets
    Kad& dht(sa_family_t af) { return af == AF_INET ? dht4 : dht6; }
    const Kad& dht(sa_family_t af) const { return af == AF_INET ? dht4 : dht6; }
    RoutingTable& buckets(sa_family_t af) { return dht(af).buckets; }
    const RoutingTable& buckets(sa_family_t af) const { return dht(af).buckets; }
    Bucket* findBucket(const InfoHash& id, sa_family_t af) {
        auto& b = buckets(af);
        auto it = b.findBucket(id);
        return it == b.end() ? nullptr : &(*it);
    }
    const Bucket* findBucket(const InfoHash& id, sa_family_t af) const {
        return const_cast<Dht*>(this)->findBucket(id, af);
    }

    void expireBuckets(RoutingTable&);
    void sendCachedPing(Bucket& b);
    bool bucketMaintenance(RoutingTable&);
    void dumpBucket(const Bucket& b, std::ostream& out) const;
    void bootstrap();
    void startBootstrap();
    void stopBootstrap();

    // Nodes
    void onNewNode(const Sp<Node>& node, int confirm);
    const Sp<Node> findNode(const InfoHash& id, sa_family_t af) const;
    bool trySearchInsert(const Sp<Node>& node);

    // Searches
    inline SearchMap& searches(sa_family_t af) { return dht(af).searches; }
    inline const SearchMap& searches(sa_family_t af) const { return dht(af).searches; }

    Sp<Search> search(const InfoHash& id, sa_family_t af, GetCallback = {}, QueryCallback = {}, DoneCallback = {}, Value::Filter = {}, const Sp<Query>& q = {});

    void announce(const InfoHash& id, sa_family_t af, Sp<Value> value, DoneCallback callback, time_point created=time_point::max(), bool permanent = false);
    size_t listenTo(const InfoHash& id, sa_family_t af, ValueCallback cb, Value::Filter f = {}, const Sp<Query>& q = {});

    unsigned refill(Search& sr);
    void expireSearches();

    void confirmNodes();
    void expire();

    void onConnected();
    void onDisconnected();

    void searchNodeGetDone(const net::Request& status,
            net::RequestAnswer&& answer,
            std::weak_ptr<Search> ws,
            Sp<Query> query);

    void searchNodeGetExpired(const net::Request& status, bool over, std::weak_ptr<Search> ws, Sp<Query> query);

    void paginate(std::weak_ptr<Search> ws, Sp<Query> query, SearchNode* n);

    SearchNode* searchSendGetValues(Sp<Search> sr, SearchNode *n = nullptr, bool update = true);

    void searchSendAnnounceValue(const Sp<Search>& sr);

    void searchStep(std::weak_ptr<Search> ws);

    void searchSynchedNodeListen(const Sp<Search>&, SearchNode&);

    void dumpSearch(const Search& sr, std::ostream& out) const;

    bool neighbourhoodMaintenance(RoutingTable&);

    void onError(Sp<net::Request> node, net::DhtProtocolException e);
    /* when our address is reported by a distant peer. */
    void onReportedAddr(const InfoHash& id, const SockAddr&);
    /* when we receive a ping request */
    net::RequestAnswer onPing(Sp<Node> node);
    /* when we receive a "find node" request */
    net::RequestAnswer onFindNode(Sp<Node> node, const InfoHash& hash, want_t want);
    void onFindNodeDone(const Sp<Node>& status,
            net::RequestAnswer& a,
            Sp<Search> sr);
    /* when we receive a "get values" request */
    net::RequestAnswer onGetValues(Sp<Node> node,
            const InfoHash& hash,
            want_t want,
            const Query& q);
    void onGetValuesDone(const Sp<Node>& status,
            net::RequestAnswer& a,
            Sp<Search>& sr,
            const Sp<Query>& orig_query);
    /* when we receive a listen request */
    net::RequestAnswer onListen(Sp<Node> node,
            const InfoHash& hash,
            const Blob& token,
            size_t socket_id,
            const Query& query,
            int version = 0);
    void onListenDone(const Sp<Node>& status,
            net::RequestAnswer& a,
            Sp<Search>& sr);
    /* when we receive an announce request */
    net::RequestAnswer onAnnounce(Sp<Node> node,
            const InfoHash& hash,
            const Blob& token,
            const std::vector<Sp<Value>>& v,
            const time_point& created);
    net::RequestAnswer onRefresh(Sp<Node> node,
            const InfoHash& hash,
            const Blob& token,
            const Value::Id& vid);
    void onAnnounceDone(const Sp<Node>& status,
            net::RequestAnswer& a,
            Sp<Search>& sr);
};

}