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1 : : // Copyright (c) 2012 Pieter Wuille
2 : : // Copyright (c) 2012-present The Bitcoin Core developers
3 : : // Distributed under the MIT software license, see the accompanying
4 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 : :
6 : : #ifndef BITCOIN_ADDRMAN_H
7 : : #define BITCOIN_ADDRMAN_H
8 : :
9 : : #include <netaddress.h>
10 : : #include <protocol.h>
11 : : #include <util/time.h>
12 : :
13 : : #include <cstddef>
14 : : #include <cstdint>
15 : : #include <ios>
16 : : #include <memory>
17 : : #include <optional>
18 : : #include <string>
19 : : #include <tuple>
20 : : #include <unordered_set>
21 : : #include <utility>
22 : : #include <vector>
23 : :
24 : : class NetGroupManager;
25 : :
26 : : /** Over how many buckets entries with tried addresses from a single group (/16 for IPv4) are spread */
27 : : static constexpr uint32_t ADDRMAN_TRIED_BUCKETS_PER_GROUP{8};
28 : : /** Over how many buckets entries with new addresses originating from a single group are spread */
29 : : static constexpr uint32_t ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP{64};
30 : : /** Maximum number of times an address can occur in the new table */
31 : : static constexpr int32_t ADDRMAN_NEW_BUCKETS_PER_ADDRESS{8};
32 : : /** How old addresses can maximally be */
33 : : static constexpr auto ADDRMAN_HORIZON{30 * 24h};
34 : : /** After how many failed attempts we give up on a new node */
35 : : static constexpr int32_t ADDRMAN_RETRIES{3};
36 : : /** How many successive failures are allowed ... */
37 : : static constexpr int32_t ADDRMAN_MAX_FAILURES{10};
38 : : /** ... in at least this duration */
39 : : static constexpr auto ADDRMAN_MIN_FAIL{7 * 24h};
40 : : /** How recent a successful connection should be before we allow an address to be evicted from tried */
41 : : static constexpr auto ADDRMAN_REPLACEMENT{4h};
42 : : /** The maximum number of tried addr collisions to store */
43 : : static constexpr size_t ADDRMAN_SET_TRIED_COLLISION_SIZE{10};
44 : : /** The maximum time we'll spend trying to resolve a tried table collision */
45 : : static constexpr auto ADDRMAN_TEST_WINDOW{40min};
46 : :
47 : : class InvalidAddrManVersionError : public std::ios_base::failure
48 : : {
49 : : public:
50 [ # # # # : 0 : InvalidAddrManVersionError(std::string msg) : std::ios_base::failure(msg) { }
# # # # ]
51 : : };
52 : :
53 : : class AddrManImpl;
54 : : class AddrInfo;
55 : :
56 : : /** Default for -checkaddrman */
57 : : static constexpr int32_t DEFAULT_ADDRMAN_CONSISTENCY_CHECKS{0};
58 : :
59 : : /** Location information for an address in AddrMan */
60 : : struct AddressPosition {
61 : : // Whether the address is in the new or tried table
62 : : const bool tried;
63 : :
64 : : // Addresses in the tried table should always have a multiplicity of 1.
65 : : // Addresses in the new table can have multiplicity between 1 and
66 : : // ADDRMAN_NEW_BUCKETS_PER_ADDRESS
67 : : const int multiplicity;
68 : :
69 : : // If the address is in the new table, the bucket and position are
70 : : // populated based on the first source who sent the address.
71 : : // In certain edge cases, this may not be where the address is currently
72 : : // located.
73 : : const int bucket;
74 : : const int position;
75 : :
76 : 2 : bool operator==(AddressPosition other) {
77 : 2 : return std::tie(tried, multiplicity, bucket, position) ==
78 : 2 : std::tie(other.tried, other.multiplicity, other.bucket, other.position);
79 : : }
80 : 14 : explicit AddressPosition(bool tried_in, int multiplicity_in, int bucket_in, int position_in)
81 [ - - ]: 14 : : tried{tried_in}, multiplicity{multiplicity_in}, bucket{bucket_in}, position{position_in} {}
82 : : };
83 : :
84 : : /** Stochastic address manager
85 : : *
86 : : * Design goals:
87 : : * * Keep the address tables in-memory, and asynchronously dump the entire table to peers.dat.
88 : : * * Make sure no (localized) attacker can fill the entire table with his nodes/addresses.
89 : : *
90 : : * To that end:
91 : : * * Addresses are organized into buckets that can each store up to 64 entries.
92 : : * * Addresses to which our node has not successfully connected go into 1024 "new" buckets.
93 : : * * Based on the address range (/16 for IPv4) of the source of information, or if an asmap is provided,
94 : : * the AS it belongs to (for IPv4/IPv6), 64 buckets are selected at random.
95 : : * * The actual bucket is chosen from one of these, based on the range in which the address itself is located.
96 : : * * The position in the bucket is chosen based on the full address.
97 : : * * One single address can occur in up to 8 different buckets to increase selection chances for addresses that
98 : : * are seen frequently. The chance for increasing this multiplicity decreases exponentially.
99 : : * * When adding a new address to an occupied position of a bucket, it will not replace the existing entry
100 : : * unless that address is also stored in another bucket or it doesn't meet one of several quality criteria
101 : : * (see IsTerrible for exact criteria).
102 : : * * Addresses of nodes that are known to be accessible go into 256 "tried" buckets.
103 : : * * Each address range selects at random 8 of these buckets.
104 : : * * The actual bucket is chosen from one of these, based on the full address.
105 : : * * When adding a new good address to an occupied position of a bucket, a FEELER connection to the
106 : : * old address is attempted. The old entry is only replaced and moved back to the "new" buckets if this
107 : : * attempt was unsuccessful.
108 : : * * Bucket selection is based on cryptographic hashing, using a randomly-generated 256-bit key, which should not
109 : : * be observable by adversaries.
110 : : * * Several indexes are kept for high performance. Setting m_consistency_check_ratio with the -checkaddrman
111 : : * configuration option will introduce (expensive) consistency checks for the entire data structure.
112 : : */
113 : : class AddrMan
114 : : {
115 : : protected:
116 : : const std::unique_ptr<AddrManImpl> m_impl;
117 : :
118 : : public:
119 : : explicit AddrMan(const NetGroupManager& netgroupman, bool deterministic, int32_t consistency_check_ratio);
120 : :
121 : : ~AddrMan();
122 : :
123 : : template <typename Stream>
124 : : void Serialize(Stream& s_) const;
125 : :
126 : : template <typename Stream>
127 : : void Unserialize(Stream& s_);
128 : :
129 : : /**
130 : : * Return size information about addrman.
131 : : *
132 : : * @param[in] net Select addresses only from specified network (nullopt = all)
133 : : * @param[in] in_new Select addresses only from one table (true = new, false = tried, nullopt = both)
134 : : * @return Number of unique addresses that match specified options.
135 : : */
136 : : size_t Size(std::optional<Network> net = std::nullopt, std::optional<bool> in_new = std::nullopt) const;
137 : :
138 : : /**
139 : : * Attempt to add one or more addresses to addrman's new table.
140 : : * If an address already exists in addrman, the existing entry may be updated
141 : : * (e.g. adding additional service flags). If the existing entry is in the new table,
142 : : * it may be added to more buckets, improving the probability of selection.
143 : : *
144 : : * @param[in] vAddr Address records to attempt to add.
145 : : * @param[in] source The address of the node that sent us these addr records.
146 : : * @param[in] time_penalty A "time penalty" to apply to the address record's nTime. If a peer
147 : : * sends us an address record with nTime=n, then we'll add it to our
148 : : * addrman with nTime=(n - time_penalty).
149 : : * @return true if at least one address is successfully added, or added to an additional bucket. Unaffected by updates. */
150 : : bool Add(const std::vector<CAddress>& vAddr, const CNetAddr& source, std::chrono::seconds time_penalty = 0s);
151 : :
152 : : /**
153 : : * Mark an address record as accessible and attempt to move it to addrman's tried table.
154 : : *
155 : : * @param[in] addr Address record to attempt to move to tried table.
156 : : * @param[in] time The time that we were last connected to this peer.
157 : : * @return true if the address is successfully moved from the new table to the tried table.
158 : : */
159 : : bool Good(const CService& addr, NodeSeconds time = Now<NodeSeconds>());
160 : :
161 : : //! Mark an entry as connection attempted to.
162 : : void Attempt(const CService& addr, bool fCountFailure, NodeSeconds time = Now<NodeSeconds>());
163 : :
164 : : //! See if any to-be-evicted tried table entries have been tested and if so resolve the collisions.
165 : : void ResolveCollisions();
166 : :
167 : : /**
168 : : * Randomly select an address in the tried table that another address is
169 : : * attempting to evict.
170 : : *
171 : : * @return CAddress The record for the selected tried peer.
172 : : * seconds The last time we attempted to connect to that peer.
173 : : */
174 : : std::pair<CAddress, NodeSeconds> SelectTriedCollision();
175 : :
176 : : /**
177 : : * Choose an address to connect to.
178 : : *
179 : : * @param[in] new_only Whether to only select addresses from the new table. Passing `true` returns
180 : : * an address from the new table or an empty pair. Passing `false` will return an
181 : : * empty pair or an address from either the new or tried table (it does not
182 : : * guarantee a tried entry).
183 : : * @param[in] networks Select only addresses of these networks (empty = all). Passing networks may
184 : : * slow down the search.
185 : : * @return CAddress The record for the selected peer.
186 : : * seconds The last time we attempted to connect to that peer.
187 : : */
188 : : std::pair<CAddress, NodeSeconds> Select(bool new_only = false, const std::unordered_set<Network>& networks = {}) const;
189 : :
190 : : /**
191 : : * Return all or many randomly selected addresses, optionally by network.
192 : : *
193 : : * @param[in] max_addresses Maximum number of addresses to return (0 = all).
194 : : * @param[in] max_pct Maximum percentage of addresses to return (0 = all). Value must be from 0 to 100.
195 : : * @param[in] network Select only addresses of this network (nullopt = all).
196 : : * @param[in] filtered Select only addresses that are considered good quality (false = all).
197 : : *
198 : : * @return A vector of randomly selected addresses from vRandom.
199 : : */
200 : : std::vector<CAddress> GetAddr(size_t max_addresses, size_t max_pct, std::optional<Network> network, bool filtered = true) const;
201 : :
202 : : /**
203 : : * Returns an information-location pair for all addresses in the selected addrman table.
204 : : * If an address appears multiple times in the new table, an information-location pair
205 : : * is returned for each occurrence. Addresses only ever appear once in the tried table.
206 : : *
207 : : * @param[in] from_tried Selects which table to return entries from.
208 : : *
209 : : * @return A vector consisting of pairs of AddrInfo and AddressPosition.
210 : : */
211 : : std::vector<std::pair<AddrInfo, AddressPosition>> GetEntries(bool from_tried) const;
212 : :
213 : : /** We have successfully connected to this peer. Calling this function
214 : : * updates the CAddress's nTime, which is used in our IsTerrible()
215 : : * decisions and gossiped to peers. Callers should be careful that updating
216 : : * this information doesn't leak topology information to network spies.
217 : : *
218 : : * net_processing calls this function when it *disconnects* from a peer to
219 : : * not leak information about currently connected peers.
220 : : *
221 : : * @param[in] addr The address of the peer we were connected to
222 : : * @param[in] time The time that we were last connected to this peer
223 : : */
224 : : void Connected(const CService& addr, NodeSeconds time = Now<NodeSeconds>());
225 : :
226 : : //! Update an entry's service bits.
227 : : void SetServices(const CService& addr, ServiceFlags nServices);
228 : :
229 : : /** Test-only function
230 : : * Find the address record in AddrMan and return information about its
231 : : * position.
232 : : * @param[in] addr The address record to look up.
233 : : * @return Information about the address record in AddrMan
234 : : * or nullopt if address is not found.
235 : : */
236 : : std::optional<AddressPosition> FindAddressEntry(const CAddress& addr);
237 : : };
238 : :
239 : : #endif // BITCOIN_ADDRMAN_H
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