Branch data     Line data    Source code

       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                 :            : class NetGroupManager {
      17                 :            : public:
      18                 :          1 :     explicit NetGroupManager(std::vector<bool> asmap)
      19                 :          1 :         : m_asmap{std::move(asmap)}
      20                 :          1 :     {}
      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                 :            : private:
      45                 :            :     /** Compressed IP->ASN mapping, loaded from a file when a node starts.
      46                 :            :      *
      47                 :            :      * This mapping is then used for bucketing nodes in Addrman and for
      48                 :            :      * ensuring we connect to a diverse set of peers in Connman. The map is
      49                 :            :      * empty if no file was provided.
      50                 :            :      *
      51                 :            :      * If asmap is provided, nodes will be bucketed by AS they belong to, in
      52                 :            :      * order to make impossible for a node to connect to several nodes hosted
      53                 :            :      * in a single AS. This is done in response to Erebus attack, but also to
      54                 :            :      * generally diversify the connections every node creates, especially
      55                 :            :      * useful when a large fraction of nodes operate under a couple of cloud
      56                 :            :      * providers.
      57                 :            :      *
      58                 :            :      * If a new asmap is provided, the existing addrman records are
      59                 :            :      * re-bucketed.
      60                 :            :      *
      61                 :            :      * This is initialized in the constructor, const, and therefore is
      62                 :            :      * thread-safe. */
      63                 :            :     const std::vector<bool> m_asmap;
      64                 :            : };
      65                 :            : 
      66                 :            : #endif // BITCOIN_NETGROUP_H