blob: 95b547ed67097a87a0cf6b74c1727c933e61f940 (
plain)
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
|
/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2017-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
package ratelimiter
import (
"net"
"sync"
"time"
)
const (
packetsPerSecond = 20
packetsBurstable = 5
garbageCollectTime = time.Second
packetCost = 1000000000 / packetsPerSecond
maxTokens = packetCost * packetsBurstable
)
type RatelimiterEntry struct {
mutex sync.Mutex
lastTime time.Time
tokens int64
}
type Ratelimiter struct {
mutex sync.RWMutex
stop chan struct{}
tableIPv4 map[[net.IPv4len]byte]*RatelimiterEntry
tableIPv6 map[[net.IPv6len]byte]*RatelimiterEntry
}
func (rate *Ratelimiter) Close() {
rate.mutex.Lock()
defer rate.mutex.Unlock()
if rate.stop != nil {
close(rate.stop)
}
}
func (rate *Ratelimiter) Init() {
rate.mutex.Lock()
defer rate.mutex.Unlock()
// stop any ongoing garbage collection routine
if rate.stop != nil {
close(rate.stop)
}
rate.stop = make(chan struct{})
rate.tableIPv4 = make(map[[net.IPv4len]byte]*RatelimiterEntry)
rate.tableIPv6 = make(map[[net.IPv6len]byte]*RatelimiterEntry)
// start garbage collection routine
go func() {
ticker := time.NewTicker(time.Second)
for {
select {
case <-rate.stop:
ticker.Stop()
return
case <-ticker.C:
func() {
rate.mutex.Lock()
defer rate.mutex.Unlock()
for key, entry := range rate.tableIPv4 {
entry.mutex.Lock()
if time.Now().Sub(entry.lastTime) > garbageCollectTime {
delete(rate.tableIPv4, key)
}
entry.mutex.Unlock()
}
for key, entry := range rate.tableIPv6 {
entry.mutex.Lock()
if time.Now().Sub(entry.lastTime) > garbageCollectTime {
delete(rate.tableIPv6, key)
}
entry.mutex.Unlock()
}
}()
}
}
}()
}
func (rate *Ratelimiter) Allow(ip net.IP) bool {
var entry *RatelimiterEntry
var keyIPv4 [net.IPv4len]byte
var keyIPv6 [net.IPv6len]byte
// lookup entry
IPv4 := ip.To4()
IPv6 := ip.To16()
rate.mutex.RLock()
if IPv4 != nil {
copy(keyIPv4[:], IPv4)
entry = rate.tableIPv4[keyIPv4]
} else {
copy(keyIPv6[:], IPv6)
entry = rate.tableIPv6[keyIPv6]
}
rate.mutex.RUnlock()
// make new entry if not found
if entry == nil {
entry = new(RatelimiterEntry)
entry.tokens = maxTokens - packetCost
entry.lastTime = time.Now()
rate.mutex.Lock()
if IPv4 != nil {
rate.tableIPv4[keyIPv4] = entry
} else {
rate.tableIPv6[keyIPv6] = entry
}
rate.mutex.Unlock()
return true
}
// add tokens to entry
entry.mutex.Lock()
now := time.Now()
entry.tokens += now.Sub(entry.lastTime).Nanoseconds()
entry.lastTime = now
if entry.tokens > maxTokens {
entry.tokens = maxTokens
}
// subtract cost of packet
if entry.tokens > packetCost {
entry.tokens -= packetCost
entry.mutex.Unlock()
return true
}
entry.mutex.Unlock()
return false
}
|
