summaryrefslogtreecommitdiff
path: root/internal/flood/flood.go
blob: 0a26edbaba08eb3c52903cf69ada63ab827473df (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
package flood

import (
	"math"
	"sort"
	"strings"
	"time"
	"unicode/utf8"

	lru "github.com/hashicorp/golang-lru"
)

const (
	runes = 6
	words = 6
	black = "\u24B6\u262D\u272F\u262E\u2721\u5350\u534D\u2719\u0FD5\u0FD6\u16CB\uA5A6\u0FD7\u0FD8"
)

type Kicker interface {
	Kick(nick string, message ...string)
	Ban(nick string)
}

type Check struct {
	k     Kicker
	cache *lru.Cache
}

func New(k Kicker) *Check {
	cache, _ := lru.New(100)
	c := &Check{k: k, cache: cache}
	go c.decay(time.Hour)
	return c
}

func (c Check) get(nick string) (int, bool) {
	if n, ok := c.cache.Get(nick); ok {
		return n.(int), true
	}
	return 0, false
}

func (c Check) del(nick string) {
	c.cache.Remove(nick)
}

func (c Check) decay(t time.Duration) {
	for range time.Tick(t) {
		for _, k := range c.cache.Keys() {
			nick := k.(string)
			n, _ := c.get(nick)
			if n > 1 {
				c.set(nick, n-1)
			} else {
				c.del(nick)
			}
		}
	}
}

func (c Check) set(nick string, n int) {
	c.cache.Add(nick, n)
}

func (c Check) Check(text, nick string) {
	if isFlood(text) {
		count, _ := c.get(nick)
		c.set(nick, count+1)
		if count >= 3 {
			c.k.Ban(nick)
			c.del(nick)
		}
		c.k.Kick(nick)
	}
}

func entropy(s string) (e float64) {
	n := make(map[rune]float64)
	for _, r := range s {
		n[r] += 1 / float64(len(s))
	}
	for _, v := range n {
		e -= v * math.Log2(v)
	}
	return e
}

func isFlood(s string) bool {
	if strings.ContainsAny(s, black) {
		return true
	}
	if utf8.RuneCountInString(s) <= runes {
		return false
	}
	if v := strings.Fields(s); len(v) >= words {
		return commonWord(v) >= len(v)/2
	}
	return entropy(s) <= 1
}

func commonWord(v []string) int {
	m := make(map[string]int)
	for _, w := range v {
		m[w]++
	}
	l := make([]int, len(m))
	for _, n := range m {
		l = append(l, n)
	}
	sort.Sort(sort.Reverse(sort.IntSlice(l)))
	return l[0]
}