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// Copyright (c) 2012 Pieter Wuille
// Copyright (c) 2012-2020 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_H
#define BITCOIN_ADDRMAN_H
#include <fs.h>
#include <logging.h>
#include <netaddress.h>
#include <protocol.h>
#include <sync.h>
#include <timedata.h>
#include <cstdint>
#include <optional>
#include <set>
#include <unordered_map>
#include <vector>
/** Default for -checkaddrman */
static constexpr int32_t DEFAULT_ADDRMAN_CONSISTENCY_CHECKS{0};
/**
* Extended statistics about a CAddress
*/
class CAddrInfo : public CAddress
{
public:
//! last try whatsoever by us (memory only)
int64_t nLastTry{0};
//! last counted attempt (memory only)
int64_t nLastCountAttempt{0};
private:
//! where knowledge about this address first came from
CNetAddr source;
//! last successful connection by us
int64_t nLastSuccess{0};
//! 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};
friend class CAddrMan;
friend class CAddrManDeterministic;
public:
SERIALIZE_METHODS(CAddrInfo, obj)
{
READWRITEAS(CAddress, obj);
READWRITE(obj.source, obj.nLastSuccess, obj.nAttempts);
}
CAddrInfo(const CAddress &addrIn, const CNetAddr &addrSource) : CAddress(addrIn), source(addrSource)
{
}
CAddrInfo() : CAddress(), source()
{
}
//! Calculate in which "tried" bucket this entry belongs
int GetTriedBucket(const uint256 &nKey, const std::vector<bool> &asmap) const;
//! Calculate in which "new" bucket this entry belongs, given a certain source
int GetNewBucket(const uint256 &nKey, const CNetAddr& src, const std::vector<bool> &asmap) const;
//! Calculate in which "new" bucket this entry belongs, using its default source
int GetNewBucket(const uint256 &nKey, const std::vector<bool> &asmap) const
{
return GetNewBucket(nKey, source, asmap);
}
//! Calculate in which position of a bucket to store this entry.
int GetBucketPosition(const uint256 &nKey, bool fNew, int nBucket) const;
//! Determine whether the statistics about this entry are bad enough so that it can just be deleted
bool IsTerrible(int64_t nNow = GetAdjustedTime()) const;
//! Calculate the relative chance this entry should be given when selecting nodes to connect to
double GetChance(int64_t nNow = GetAdjustedTime()) const;
};
/** Stochastic address manager
*
* Design goals:
* * Keep the address tables in-memory, and asynchronously dump the entire table to peers.dat.
* * Make sure no (localized) attacker can fill the entire table with his nodes/addresses.
*
* To that end:
* * Addresses are organized into buckets that can each store up to 64 entries.
* * Addresses to which our node has not successfully connected go into 1024 "new" buckets.
* * Based on the address range (/16 for IPv4) of the source of information, or if an asmap is provided,
* the AS it belongs to (for IPv4/IPv6), 64 buckets are selected at random.
* * The actual bucket is chosen from one of these, based on the range in which the address itself is located.
* * The position in the bucket is chosen based on the full address.
* * One single address can occur in up to 8 different buckets to increase selection chances for addresses that
* are seen frequently. The chance for increasing this multiplicity decreases exponentially.
* * When adding a new address to an occupied position of a bucket, it will not replace the existing entry
* unless that address is also stored in another bucket or it doesn't meet one of several quality criteria
* (see IsTerrible for exact criteria).
* * Addresses of nodes that are known to be accessible go into 256 "tried" buckets.
* * Each address range selects at random 8 of these buckets.
* * The actual bucket is chosen from one of these, based on the full address.
* * When adding a new good address to an occupied position of a bucket, a FEELER connection to the
* old address is attempted. The old entry is only replaced and moved back to the "new" buckets if this
* attempt was unsuccessful.
* * Bucket selection is based on cryptographic hashing, using a randomly-generated 256-bit key, which should not
* be observable by adversaries.
* * Several indexes are kept for high performance. Setting m_consistency_check_ratio with the -checkaddrman
* configuration option will introduce (expensive) consistency checks for the entire data structure.
*/
/** 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};
/**
* Stochastical (IP) address manager
*/
class CAddrMan
{
public:
explicit CAddrMan(std::vector<bool> asmap, bool deterministic, int32_t consistency_check_ratio);
~CAddrMan();
template <typename Stream>
void Serialize(Stream& s_) const EXCLUSIVE_LOCKS_REQUIRED(!cs);
template <typename Stream>
void Unserialize(Stream& s_) EXCLUSIVE_LOCKS_REQUIRED(!cs);
//! Return the number of (unique) addresses in all tables.
size_t size() const EXCLUSIVE_LOCKS_REQUIRED(!cs);
//! Add addresses to addrman's new table.
bool Add(const std::vector<CAddress> &vAddr, const CNetAddr& source, int64_t nTimePenalty = 0)
EXCLUSIVE_LOCKS_REQUIRED(!cs);
//! Mark an entry as accessible.
void Good(const CService &addr, int64_t nTime = GetAdjustedTime())
EXCLUSIVE_LOCKS_REQUIRED(!cs);
//! Mark an entry as connection attempted to.
void Attempt(const CService &addr, bool fCountFailure, int64_t nTime = GetAdjustedTime())
EXCLUSIVE_LOCKS_REQUIRED(!cs);
//! See if any to-be-evicted tried table entries have been tested and if so resolve the collisions.
void ResolveCollisions() EXCLUSIVE_LOCKS_REQUIRED(!cs);
//! Randomly select an address in tried that another address is attempting to evict.
CAddrInfo SelectTriedCollision() EXCLUSIVE_LOCKS_REQUIRED(!cs);
/**
* Choose an address to connect to.
*/
CAddrInfo Select(bool newOnly = false) const EXCLUSIVE_LOCKS_REQUIRED(!cs);
/**
* Return all or many randomly selected addresses, optionally by network.
*
* @param[in] max_addresses Maximum number of addresses to return (0 = all).
* @param[in] max_pct Maximum percentage of addresses to return (0 = all).
* @param[in] network Select only addresses of this network (nullopt = all).
*/
std::vector<CAddress> GetAddr(size_t max_addresses, size_t max_pct, std::optional<Network> network) const
EXCLUSIVE_LOCKS_REQUIRED(!cs);
//! Outer function for Connected_()
void Connected(const CService &addr, int64_t nTime = GetAdjustedTime())
EXCLUSIVE_LOCKS_REQUIRED(!cs);
void SetServices(const CService &addr, ServiceFlags nServices)
EXCLUSIVE_LOCKS_REQUIRED(!cs);
const std::vector<bool>& GetAsmap() const;
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
};
//! 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::V3_BIP155;
//! 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
int nIdCount GUARDED_BY(cs){0};
//! table with information about all nIds
std::unordered_map<int, CAddrInfo> mapInfo GUARDED_BY(cs);
//! find an nId based on its network address
std::unordered_map<CNetAddr, int, CNetAddrHash> 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<int> vRandom GUARDED_BY(cs);
// number of "tried" entries
int nTried GUARDED_BY(cs){0};
//! list of "tried" buckets
int 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
int 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.
int64_t nLastGood GUARDED_BY(cs){1};
//! Holds addrs inserted into tried table that collide with existing entries. Test-before-evict discipline used to resolve these collisions.
std::set<int> m_tried_collisions;
/** Perform consistency checks every m_consistency_check_ratio operations (if non-zero). */
const int32_t m_consistency_check_ratio;
// Compressed IP->ASN mapping, loaded from a file when a node starts.
// Should be always empty if no file was provided.
// This mapping is then used for bucketing nodes in Addrman.
//
// If asmap is provided, nodes will be bucketed by
// AS they belong to, in order to make impossible for a node
// to connect to several nodes hosted in a single AS.
// This is done in response to Erebus attack, but also to generally
// diversify the connections every node creates,
// especially useful when a large fraction of nodes
// operate under a couple of cloud providers.
//
// If a new asmap was provided, the existing records
// would be re-bucketed accordingly.
const std::vector<bool> m_asmap;
//! Find an entry.
CAddrInfo* Find(const CNetAddr& addr, int *pnId = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Create a new entry and add it to the internal data structures mapInfo, mapAddr and vRandom.
CAddrInfo* Create(const CAddress &addr, const CNetAddr &addrSource, int *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(int 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(CAddrInfo& info, int nId) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Mark an entry "good", possibly moving it from "new" to "tried".
void Good_(const CService &addr, bool test_before_evict, int64_t time) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Add an entry to the "new" table.
bool Add_(const CAddress &addr, const CNetAddr& source, int64_t nTimePenalty) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Mark an entry as attempted to connect.
void Attempt_(const CService &addr, bool fCountFailure, int64_t nTime) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Select an address to connect to, if newOnly is set to true, only the new table is selected from.
CAddrInfo Select_(bool newOnly) const EXCLUSIVE_LOCKS_REQUIRED(cs);
/**
* Return all or many randomly selected addresses, optionally by network.
*
* @param[out] vAddr Vector of randomly selected addresses from vRandom.
* @param[in] max_addresses Maximum number of addresses to return (0 = all).
* @param[in] max_pct Maximum percentage of addresses to return (0 = all).
* @param[in] network Select only addresses of this network (nullopt = all).
*/
void GetAddr_(std::vector<CAddress>& vAddr, size_t max_addresses, size_t max_pct, std::optional<Network> network) const EXCLUSIVE_LOCKS_REQUIRED(cs);
/** We have successfully connected to this peer. Calling this function
* updates the CAddress's nTime, which is used in our IsTerrible()
* decisions and gossiped to peers. Callers should be careful that updating
* this information doesn't leak topology information to network spies.
*
* net_processing calls this function when it *disconnects* from a peer to
* not leak information about currently connected peers.
*
* @param[in] addr The address of the peer we were connected to
* @param[in] nTime The time that we were last connected to this peer
*/
void Connected_(const CService& addr, int64_t nTime) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Update an entry's service bits.
void SetServices_(const CService &addr, ServiceFlags nServices) EXCLUSIVE_LOCKS_REQUIRED(cs);
//! See if any to-be-evicted tried table entries have been tested and if so resolve the collisions.
void ResolveCollisions_() EXCLUSIVE_LOCKS_REQUIRED(cs);
//! Return a random to-be-evicted tried table address.
CAddrInfo SelectTriedCollision_() 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 ForceCheckAddrman() const EXCLUSIVE_LOCKS_REQUIRED(cs);
friend class CAddrManTest;
friend class CAddrManDeterministic;
};
#endif // BITCOIN_ADDRMAN_H
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