1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179

crate::ix!();

pub trait RelayAddress {

    fn relay_address(self: Arc<Self>, 
        originator: NodeId,
        addr:       &Address,
        reachable:  bool);
}

impl RelayAddress for PeerManager {

    /**
      | Relay (gossip) an address to a few randomly
      | chosen nodes.
      | 
      | -----------
      | @param[in] originator
      | 
      | The id of the peer that sent us the address.
      | We don't want to relay it back.
      | ----------
      | @param[in] addr
      | 
      | Address to relay.
      | ----------
      | @param[in] fReachable
      | 
      | Whether the address' network is reachable.
      | We relay unreachable addresses less.
      |
      */
    fn relay_address(
        self:       Arc<Self>, 
        originator: NodeId,
        addr:       &Address,
        reachable:  bool)  {

        // We choose the same nodes within a given
        // 24h window (if the list of connected
        // nodes does not change) and we don't
        // relay to nodes that already know an
        // address. 
        //
        // So within 24h we will likely relay
        // a given address once. This is to
        // prevent a peer from unjustly giving
        // their address better propagation by
        // sending it to us repeatedly.
        if !reachable && !addr.is_relayable() {
            return;
        }

        // Relay to a limited number of other
        // nodes
        //
        // Use deterministic randomness to send to
        // the same nodes for 24 hours at a time
        // so the m_addr_knowns of the chosen
        // nodes prevent repeats
        let hash_addr: u64 = addr.get_hash();

        let mut hasher: SipHasher = self.connman.get()
            .get_deterministic_randomizer(RANDOMIZER_ID_ADDRESS_RELAY);

        hasher.write_u64(hash_addr << 32);

        hasher.write_u64(
            (u64::try_from(get_datetime().unix_timestamp()).unwrap() + hash_addr) / (24 * 60 * 60)
        );

        let mut insecure_rand = FastRandomContext::default();

        // We choose the same nodes within a given
        // 24h window (if the list of connected
        // nodes does not change) and we don't
        // relay to nodes that already know an
        // address. So within 24h we will likely
        // relay a given address once. This is to
        // prevent a peer from unjustly giving
        // their address better propagation by
        // sending it to us repeatedly.
        if !reachable && !addr.is_relayable() {
            return;
        }

        // Relay to a limited number of other
        // nodes
        //
        // Use deterministic randomness to send to
        // the same nodes for 24 hours at a time
        // so the m_addr_knowns of the chosen
        // nodes prevent repeats
        let hash_addr: u64 = addr.get_hash();

        let mut hasher: SipHasher = self.connman.get()
            .get_deterministic_randomizer(RANDOMIZER_ID_ADDRESS_RELAY);

        hasher.write_u64(hash_addr << 32);

        hasher.write_u64(
            (u64::try_from(get_datetime().unix_timestamp()).unwrap() + hash_addr) / (24 * 60 * 60)
        );

        let mut insecure_rand = FastRandomContext::default();

        // Relay reachable addresses to
        // 2 peers. Unreachable addresses are
        // relayed randomly to 1 or 2 peers.
        let n_relay_nodes: usize = match reachable || (hasher.finish() & 1) != 0 {
            true   => 2,
            false  => 1
        };

        struct Item {
            first:  u64,
            second: Amo<Peer>,
        }

        let mut best: Vec<Item> = vec![
            Item { first: 0, second: amo_none() }, 
            Item { first: 0, second: amo_none() }
        ];

        assert!(n_relay_nodes <= best.len());

        let mut peer_map = self.peer_map.get();

        for (id,peer) in peer_map.iter() {

            if peer.get().addr_relay_enabled.load(atomic::Ordering::Relaxed) 
            && *id != originator 
            && peer.get().is_addr_compatible(addr) 
            {
                let mut siphasher = SipHasher::from(hasher.clone());

                siphasher.write_i64(*id);

                let hash_key: u64 = siphasher.finish();

                for i in 0_usize..n_relay_nodes {

                    if hash_key > best[i].first 
                    {
                        let src = &best[i..n_relay_nodes - 1];

                        let rmin = i + 1;
                        let rmax = n_relay_nodes - 1;

                        let range = 
                            (i + 1)
                            ..
                            (i + 1 + src.len());

                        let other: Vec<Item> = best.drain(rmin..=rmax).collect();

                        best.splice( range, other );

                        best[i] = Item { first: hash_key, second: peer.clone() };

                        break;
                    }
                }
            }
        }

        let mut i: usize = 0;

        while i < n_relay_nodes.try_into().unwrap() && best[i].first != 0 
        {
            best[i].second.get_mut().push_address(
                addr, 
                &mut insecure_rand
            );

            i += 1;
        }
    }
}