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