1  // Copyright (c) 2009-2010 Satoshi Nakamoto
 2  // Copyright (c) 2009-2022 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  #ifndef BITCOIN_BANMAN_H
 6  #define BITCOIN_BANMAN_H
 7  
 8  #include <addrdb.h>
 9  #include <common/bloom.h>
10  #include <net_types.h> // For banmap_t
11  #include <sync.h>
12  #include <util/fs.h>
13  
14  #include <chrono>
15  #include <cstdint>
16  #include <memory>
17  
18  // NOTE: When adjusting this, update rpcnet:setban's help ("24h")
19  static constexpr unsigned int DEFAULT_MISBEHAVING_BANTIME = 60 * 60 * 24; // Default 24-hour ban
20  
21  /// How often to dump banned addresses/subnets to disk.
22  static constexpr std::chrono::minutes DUMP_BANS_INTERVAL{15};
23  
24  class CClientUIInterface;
25  class CNetAddr;
26  class CSubNet;
27  
28  // Banman manages two related but distinct concepts:
29  //
30  // 1. Banning. This is configured manually by the user, through the setban RPC.
31  // If an address or subnet is banned, we never accept incoming connections from
32  // it and never create outgoing connections to it. We won't gossip its address
33  // to other peers in addr messages. Banned addresses and subnets are stored to
34  // disk on shutdown and reloaded on startup. Banning can be used to
35  // prevent connections with spy nodes or other griefers.
36  //
37  // 2. Discouragement. If a peer misbehaves enough (see Misbehaving() in
38  // net_processing.cpp), we'll mark that address as discouraged. We still allow
39  // incoming connections from them, but they're preferred for eviction when
40  // we receive new incoming connections. We never make outgoing connections to
41  // them, and do not gossip their address to other peers. This is implemented as
42  // a bloom filter. We can (probabilistically) test for membership, but can't
43  // list all discouraged addresses or unmark them as discouraged. Discouragement
44  // can prevent our limited connection slots being used up by incompatible
45  // or broken peers.
46  //
47  // Neither banning nor discouragement are protections against denial-of-service
48  // attacks, since if an attacker has a way to waste our resources and we
49  // disconnect from them and ban that address, it's trivial for them to
50  // reconnect from another IP address.
51  //
52  // Attempting to automatically disconnect or ban any class of peer carries the
53  // risk of splitting the network. For example, if we banned/disconnected for a
54  // transaction that fails a policy check and a future version changes the
55  // policy check so the transaction is accepted, then that transaction could
56  // cause the network to split between old nodes and new nodes.
57  
58  class BanMan
59  {
60  public:
61      ~BanMan();
62      BanMan(fs::path ban_file, CClientUIInterface* client_interface, int64_t default_ban_time);
63      void Ban(const CNetAddr& net_addr, int64_t ban_time_offset = 0, bool since_unix_epoch = false) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
64      void Ban(const CSubNet& sub_net, int64_t ban_time_offset = 0, bool since_unix_epoch = false) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
65      void Discourage(const CNetAddr& net_addr) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
66      void ClearBanned() EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
67  
68      //! Return whether net_addr is banned
69      bool IsBanned(const CNetAddr& net_addr) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
70  
71      //! Return whether sub_net is exactly banned
72      bool IsBanned(const CSubNet& sub_net) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
73  
74      //! Return whether net_addr is discouraged.
75      bool IsDiscouraged(const CNetAddr& net_addr) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
76  
77      bool Unban(const CNetAddr& net_addr) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
78      bool Unban(const CSubNet& sub_net) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
79      void GetBanned(banmap_t& banmap) EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
80      void DumpBanlist() EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
81  
82  private:
83      void LoadBanlist() EXCLUSIVE_LOCKS_REQUIRED(!m_banned_mutex);
84      //!clean unused entries (if bantime has expired)
85      void SweepBanned() EXCLUSIVE_LOCKS_REQUIRED(m_banned_mutex);
86  
87      Mutex m_banned_mutex;
88      banmap_t m_banned GUARDED_BY(m_banned_mutex);
89      bool m_is_dirty GUARDED_BY(m_banned_mutex){false};
90      CClientUIInterface* m_client_interface = nullptr;
91      CBanDB m_ban_db;
92      const int64_t m_default_ban_time;
93      CRollingBloomFilter m_discouraged GUARDED_BY(m_banned_mutex) {50000, 0.000001};
94  };
95  
96  #endif // BITCOIN_BANMAN_H