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       1                 :             : // Copyright (c) 2021 The Bitcoin Core developers
       2                 :             : // Distributed under the MIT software license, see the accompanying
       3                 :             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       4                 :             : 
       5                 :             : #ifndef BITCOIN_NETGROUP_H
       6                 :             : #define BITCOIN_NETGROUP_H
       7                 :             : 
       8                 :             : #include <netaddress.h>
       9                 :             : #include <uint256.h>
      10                 :             : 
      11                 :             : #include <vector>
      12                 :             : 
      13                 :             : /**
      14                 :             :  * Netgroup manager
      15                 :             :  */
      16                 :         169 : class NetGroupManager {
      17                 :             : public:
      18                 :         169 :     explicit NetGroupManager(std::vector<bool> asmap)
      19                 :         169 :         : m_asmap{std::move(asmap)}
      20                 :             :     {}
      21                 :             : 
      22                 :             :     /** Get a checksum identifying the asmap being used. */
      23                 :             :     uint256 GetAsmapChecksum() const;
      24                 :             : 
      25                 :             :     /**
      26                 :             :      * Get the canonical identifier of the network group for address.
      27                 :             :      *
      28                 :             :      * The groups are assigned in a way where it should be costly for an attacker to
      29                 :             :      * obtain addresses with many different group identifiers, even if it is cheap
      30                 :             :      * to obtain addresses with the same identifier.
      31                 :             :      *
      32                 :             :      * @note No two connections will be attempted to addresses with the same network
      33                 :             :      *       group.
      34                 :             :      */
      35                 :             :     std::vector<unsigned char> GetGroup(const CNetAddr& address) const;
      36                 :             : 
      37                 :             :     /**
      38                 :             :      *  Get the autonomous system on the BGP path to address.
      39                 :             :      *
      40                 :             :      *  The ip->AS mapping depends on how asmap is constructed.
      41                 :             :      */
      42                 :             :     uint32_t GetMappedAS(const CNetAddr& address) const;
      43                 :             : 
      44                 :             :     /**
      45                 :             :      *  Analyze and log current health of ASMap based buckets.
      46                 :             :      */
      47                 :             :     void ASMapHealthCheck(const std::vector<CNetAddr>& clearnet_addrs) const;
      48                 :             : 
      49                 :             :     /**
      50                 :             :      *  Indicates whether ASMap is being used for clearnet bucketing.
      51                 :             :      */
      52                 :             :     bool UsingASMap() const;
      53                 :             : 
      54                 :             : private:
      55                 :             :     /** Compressed IP->ASN mapping, loaded from a file when a node starts.
      56                 :             :      *
      57                 :             :      * This mapping is then used for bucketing nodes in Addrman and for
      58                 :             :      * ensuring we connect to a diverse set of peers in Connman. The map is
      59                 :             :      * empty if no file was provided.
      60                 :             :      *
      61                 :             :      * If asmap is provided, nodes will be bucketed by AS they belong to, in
      62                 :             :      * order to make impossible for a node to connect to several nodes hosted
      63                 :             :      * in a single AS. This is done in response to Erebus attack, but also to
      64                 :             :      * generally diversify the connections every node creates, especially
      65                 :             :      * useful when a large fraction of nodes operate under a couple of cloud
      66                 :             :      * providers.
      67                 :             :      *
      68                 :             :      * If a new asmap is provided, the existing addrman records are
      69                 :             :      * re-bucketed.
      70                 :             :      *
      71                 :             :      * This is initialized in the constructor, const, and therefore is
      72                 :             :      * thread-safe. */
      73                 :             :     const std::vector<bool> m_asmap;
      74                 :             : };
      75                 :             : 
      76                 :             : #endif // BITCOIN_NETGROUP_H