summaryrefslogtreecommitdiff
path: root/mask.go
blob: 14fb1b35852442fb198bb1862e2e0fb916ba2719 (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
package main

import (
	"strings"
	"unicode"
)

func isIPv4(addr string) bool {
	for _, v := range addr {
		if v != '.' && !unicode.IsDigit(v) {
			return false
		}
	}
	return true
}

func domainMask(addr string) string {
	// no dots - TLD or IPv6
	if !strings.Contains(addr, ".") {
		if i := strings.LastIndex(addr, ":"); i >= 0 {
			// IPv6, ban last 64k addresses
			return addr[:i+1] + "*"
		}
	}
	if isIPv4(addr) {
		// IPv4, change last digit to *
		if i := strings.LastIndex(addr, "."); i >= 0 {
			return addr[:i+1] + "*"
		}
	}
	// more then one dot, skip the first
	if i := strings.Index(addr, "."); i >= 0 {
		if strings.Index(addr[i+1:], ".") >= 0 {
			return "*" + addr[i:]
		}
	}
	return addr
}

func isHostFlag(addr string) bool {
	if addr == "" {
		return false
	}
	switch addr[0] {
	case '^', '~', '+', '=', '-':
		return true
	}
	return false
}

func mask(addr string) string {
	// strip -, ^ or ~ from start
	if isHostFlag(addr) {
		addr = addr[1:]
	}
	// split user and host
	s := strings.SplitN(addr, "@", 2)
	if len(s) != 2 {
		return "*!*" + addr
	}
	user, host := s[0], domainMask(s[1])
	return "*!*" + user + "@" + host
}