src/addrman_impl.h

	// Copyright (c) 2021-2022 The Bitcoin Core developers
	// Distributed under the MIT software license, see the accompanying
	// file COPYING or http://www.opensource.org/licenses/mit-license.php.

	#ifndef BITCOIN_ADDRMAN_IMPL_H
	#define BITCOIN_ADDRMAN_IMPL_H

	#include <logging.h>
	#include <logging/timer.h>
	#include <netaddress.h>
	#include <protocol.h>
	#include <serialize.h>
	#include <sync.h>
	#include <uint256.h>
	#include <util/time.h>

	#include <cstdint>
	#include <optional>
	#include <set>
	#include <unordered_map>
	#include <unordered_set>
	#include <utility>
	#include <vector>

	/** Total number of buckets for tried addresses */
	static constexpr int32_t ADDRMAN_TRIED_BUCKET_COUNT_LOG2{8};
	static constexpr int ADDRMAN_TRIED_BUCKET_COUNT{1 << ADDRMAN_TRIED_BUCKET_COUNT_LOG2};
	/** Total number of buckets for new addresses */
	static constexpr int32_t ADDRMAN_NEW_BUCKET_COUNT_LOG2{10};
	static constexpr int ADDRMAN_NEW_BUCKET_COUNT{1 << ADDRMAN_NEW_BUCKET_COUNT_LOG2};
	/** Maximum allowed number of entries in buckets for new and tried addresses */
	static constexpr int32_t ADDRMAN_BUCKET_SIZE_LOG2{6};
	static constexpr int ADDRMAN_BUCKET_SIZE{1 << ADDRMAN_BUCKET_SIZE_LOG2};

	/**
	* User-defined type for the internally used nIds
	* This used to be int, making it feasible for attackers to cause an overflow,
	* see https://bitcoincore.org/en/2024/07/31/disclose-addrman-int-overflow/
	*/
	using nid_type = int64_t;

	/**
	* Extended statistics about a CAddress
	*/
	class AddrInfo : public CAddress
	{
	public:
	//! last try whatsoever by us (memory only)
	NodeSeconds m_last_try{0s};

	//! last counted attempt (memory only)
	NodeSeconds m_last_count_attempt{0s};

	//! where knowledge about this address first came from
	CNetAddr source;

	//! last successful connection by us
	NodeSeconds m_last_success{0s};

	//! connection attempts since last successful attempt
	int nAttempts{0};

	//! reference count in new sets (memory only)
	int nRefCount{0};

	//! in tried set? (memory only)
	bool fInTried{false};

	//! position in vRandom
	mutable int nRandomPos{-1};

	SERIALIZE_METHODS(AddrInfo, obj)
	{
	READWRITE(AsBase<CAddress>(obj), obj.source, Using<ChronoFormatter<int64_t>>(obj.m_last_success), obj.nAttempts);
	}

	AddrInfo(const CAddress &addrIn, const CNetAddr &addrSource) : CAddress(addrIn), source(addrSource)
	{
	}

	AddrInfo() : CAddress(), source()
	{
	}

	//! Calculate in which "tried" bucket this entry belongs
	int GetTriedBucket(const uint256& nKey, const NetGroupManager& netgroupman) const;

	//! Calculate in which "new" bucket this entry belongs, given a certain source
	int GetNewBucket(const uint256& nKey, const CNetAddr& src, const NetGroupManager& netgroupman) const;

	//! Calculate in which "new" bucket this entry belongs, using its default source
	int GetNewBucket(const uint256& nKey, const NetGroupManager& netgroupman) const
	{
	return GetNewBucket(nKey, source, netgroupman);
	}

	//! Calculate in which position of a bucket to store this entry.
	int GetBucketPosition(const uint256 &nKey, bool fNew, int bucket) const;

	//! Determine whether the statistics about this entry are bad enough so that it can just be deleted
	bool IsTerrible(NodeSeconds now = Now<NodeSeconds>()) const;

	//! Calculate the relative chance this entry should be given when selecting nodes to connect to
	double GetChance(NodeSeconds now = Now<NodeSeconds>()) const;
	};

	class AddrManImpl
	{
	public:
	AddrManImpl(const NetGroupManager& netgroupman, bool deterministic, int32_t consistency_check_ratio);

	~AddrManImpl();

	template <typename Stream>
	void Serialize(Stream& s_) const EXCLUSIVE_LOCKS_REQUIRED(!cs);

	template <typename Stream>
	void Unserialize(Stream& s_) EXCLUSIVE_LOCKS_REQUIRED(!cs);

	size_t Size(std::optional<Network> net, std::optional<bool> in_new) const EXCLUSIVE_LOCKS_REQUIRED(!cs);

	bool Add(const std::vector<CAddress>& vAddr, const CNetAddr& source, std::chrono::seconds time_penalty)
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	bool Good(const CService& addr, NodeSeconds time)
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	void Attempt(const CService& addr, bool fCountFailure, NodeSeconds time)
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	void ResolveCollisions() EXCLUSIVE_LOCKS_REQUIRED(!cs);

	std::pair<CAddress, NodeSeconds> SelectTriedCollision() EXCLUSIVE_LOCKS_REQUIRED(!cs);

	std::pair<CAddress, NodeSeconds> Select(bool new_only, const std::unordered_set<Network>& networks) const
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	std::vector<CAddress> GetAddr(size_t max_addresses, size_t max_pct, std::optional<Network> network, const bool filtered = true) const
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	std::vector<std::pair<AddrInfo, AddressPosition>> GetEntries(bool from_tried) const
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	void Connected(const CService& addr, NodeSeconds time)
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	void SetServices(const CService& addr, ServiceFlags nServices)
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	std::optional<AddressPosition> FindAddressEntry(const CAddress& addr)
	EXCLUSIVE_LOCKS_REQUIRED(!cs);

	friend class AddrManDeterministic;

	private:
	//! A mutex to protect the inner data structures.
	mutable Mutex cs;

	//! Source of random numbers for randomization in inner loops
	mutable FastRandomContext insecure_rand GUARDED_BY(cs);

	//! secret key to randomize bucket select with
	uint256 nKey;

	//! Serialization versions.
	enum Format : uint8_t {
	V0_HISTORICAL = 0, //!< historic format, before commit e6b343d88
	V1_DETERMINISTIC = 1, //!< for pre-asmap files
	V2_ASMAP = 2, //!< for files including asmap version
	V3_BIP155 = 3, //!< same as V2_ASMAP plus addresses are in BIP155 format
	V4_MULTIPORT = 4, //!< adds support for multiple ports per IP
	};

	//! The maximum format this software knows it can unserialize. Also, we always serialize
	//! in this format.
	//! The format (first byte in the serialized stream) can be higher than this and
	//! still this software may be able to unserialize the file - if the second byte
	//! (see `lowest_compatible` in `Unserialize()`) is less or equal to this.
	static constexpr Format FILE_FORMAT = Format::V4_MULTIPORT;

	//! The initial value of a field that is incremented every time an incompatible format
	//! change is made (such that old software versions would not be able to parse and
	//! understand the new file format). This is 32 because we overtook the "key size"
	//! field which was 32 historically.
	//! @note Don't increment this. Increment `lowest_compatible` in `Serialize()` instead.
	static constexpr uint8_t INCOMPATIBILITY_BASE = 32;

	//! last used nId
	nid_type nIdCount GUARDED_BY(cs){0};

	//! table with information about all nIds
	std::unordered_map<nid_type, AddrInfo> mapInfo GUARDED_BY(cs);

	//! find an nId based on its network address and port.
	std::unordered_map<CService, nid_type, CServiceHash> mapAddr GUARDED_BY(cs);

	//! randomly-ordered vector of all nIds
	//! This is mutable because it is unobservable outside the class, so any
	//! changes to it (even in const methods) are also unobservable.
	mutable std::vector<nid_type> vRandom GUARDED_BY(cs);

	// number of "tried" entries
	int nTried GUARDED_BY(cs){0};

	//! list of "tried" buckets
	nid_type vvTried[ADDRMAN_TRIED_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);

	//! number of (unique) "new" entries
	int nNew GUARDED_BY(cs){0};

	//! list of "new" buckets
	nid_type vvNew[ADDRMAN_NEW_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);

	//! last time Good was called (memory only). Initially set to 1 so that "never" is strictly worse.
	NodeSeconds m_last_good GUARDED_BY(cs){1s};

	//! Holds addrs inserted into tried table that collide with existing entries. Test-before-evict discipline used to resolve these collisions.
	std::set<nid_type> m_tried_collisions;

	/** Perform consistency checks every m_consistency_check_ratio operations (if non-zero). */
	const int32_t m_consistency_check_ratio;

	/** Reference to the netgroup manager. netgroupman must be constructed before addrman and destructed after. */
	const NetGroupManager& m_netgroupman;

	struct NewTriedCount {
	size_t n_new;
	size_t n_tried;
	};

	/** Number of entries in addrman per network and new/tried table. */
	std::unordered_map<Network, NewTriedCount> m_network_counts GUARDED_BY(cs);

	//! Find an entry.
	AddrInfo* Find(const CService& addr, nid_type* pnId = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs);

	//! Create a new entry and add it to the internal data structures mapInfo, mapAddr and vRandom.
	AddrInfo* Create(const CAddress& addr, const CNetAddr& addrSource, nid_type* pnId = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs);

	//! Swap two elements in vRandom.
	void SwapRandom(unsigned int nRandomPos1, unsigned int nRandomPos2) const EXCLUSIVE_LOCKS_REQUIRED(cs);

	//! Delete an entry. It must not be in tried, and have refcount 0.
	void Delete(nid_type nId) EXCLUSIVE_LOCKS_REQUIRED(cs);

	//! Clear a position in a "new" table. This is the only place where entries are actually deleted.
	void ClearNew(int nUBucket, int nUBucketPos) EXCLUSIVE_LOCKS_REQUIRED(cs);

	//! Move an entry from the "new" table(s) to the "tried" table
	void MakeTried(AddrInfo& info, nid_type nId) EXCLUSIVE_LOCKS_REQUIRED(cs);

	/** Attempt to add a single address to addrman's new table.
	* @see AddrMan::Add() for parameters. */
	bool AddSingle(const CAddress& addr, const CNetAddr& source, std::chrono::seconds time_penalty) EXCLUSIVE_LOCKS_REQUIRED(cs);

	bool Good_(const CService& addr, bool test_before_evict, NodeSeconds time) EXCLUSIVE_LOCKS_REQUIRED(cs);

	bool Add_(const std::vector<CAddress>& vAddr, const CNetAddr& source, std::chrono::seconds time_penalty) EXCLUSIVE_LOCKS_REQUIRED(cs);

	void Attempt_(const CService& addr, bool fCountFailure, NodeSeconds time) EXCLUSIVE_LOCKS_REQUIRED(cs);

	std::pair<CAddress, NodeSeconds> Select_(bool new_only, const std::unordered_set<Network>& networks) const EXCLUSIVE_LOCKS_REQUIRED(cs);

	/** Helper to generalize looking up an addrman entry from either table.
	*
	* @return nid_type The nid of the entry. If the addrman position is empty or not found, returns -1.
	* */
	nid_type GetEntry(bool use_tried, size_t bucket, size_t position) const EXCLUSIVE_LOCKS_REQUIRED(cs);

	std::vector<CAddress> GetAddr_(size_t max_addresses, size_t max_pct, std::optional<Network> network, const bool filtered = true) const EXCLUSIVE_LOCKS_REQUIRED(cs);

	std::vector<std::pair<AddrInfo, AddressPosition>> GetEntries_(bool from_tried) const EXCLUSIVE_LOCKS_REQUIRED(cs);

	void Connected_(const CService& addr, NodeSeconds time) EXCLUSIVE_LOCKS_REQUIRED(cs);

	void SetServices_(const CService& addr, ServiceFlags nServices) EXCLUSIVE_LOCKS_REQUIRED(cs);

	void ResolveCollisions_() EXCLUSIVE_LOCKS_REQUIRED(cs);

	std::pair<CAddress, NodeSeconds> SelectTriedCollision_() EXCLUSIVE_LOCKS_REQUIRED(cs);

	std::optional<AddressPosition> FindAddressEntry_(const CAddress& addr) EXCLUSIVE_LOCKS_REQUIRED(cs);

	size_t Size_(std::optional<Network> net, std::optional<bool> in_new) const EXCLUSIVE_LOCKS_REQUIRED(cs);

	//! Consistency check, taking into account m_consistency_check_ratio.
	//! Will std::abort if an inconsistency is detected.
	void Check() const EXCLUSIVE_LOCKS_REQUIRED(cs);

	//! Perform consistency check, regardless of m_consistency_check_ratio.
	//! @returns an error code or zero.
	int CheckAddrman() const EXCLUSIVE_LOCKS_REQUIRED(cs);
	};

	#endif // BITCOIN_ADDRMAN_IMPL_H

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