/
rfc1035.go
65 lines (57 loc) · 1.92 KB
/
rfc1035.go
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
// Copyright 2019 Altinity Ltd and/or its affiliates. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package util
import (
"regexp"
"strings"
)
const dns1035LabelMaxLength int = 63
const dns1035LabelFormat string = "[a-z]([-a-z0-9]*[a-z0-9])?"
const dns1035LabelStartFormat string = "[a-z]"
const dns1035LabelNotAllowedCharsFormat string = "[^-a-z0-9]"
var dns1035LabelRegexp = regexp.MustCompile("^" + dns1035LabelFormat + "$")
var dns1035LabelStartRegexp = regexp.MustCompile("^" + dns1035LabelStartFormat)
var dns1035LabelNotAllowedCharsRegexp = regexp.MustCompile(dns1035LabelNotAllowedCharsFormat)
func BuildRFC1035Label(str string) (string, bool) {
// Must be lowercase
str = strings.ToLower(str)
// First char must comply to start regexp
for len(str) > 0 {
if dns1035LabelStartRegexp.MatchString(str) {
break
} else {
str = str[1:]
}
}
// Remove not allowed chars
str = dns1035LabelNotAllowedCharsRegexp.ReplaceAllString(str, "")
// Must have limited length
if len(str) > dns1035LabelMaxLength {
str = str[0:dns1035LabelMaxLength]
}
if IsValidDNS1035Label(str) {
return str, true
}
return "", false
}
// IsValidDNS1035Label tests for a string that conforms to the definition of a label in DNS (RFC 1035).
func IsValidDNS1035Label(value string) bool {
if len(value) > dns1035LabelMaxLength {
return false
}
if !dns1035LabelRegexp.MatchString(value) {
return false
}
return true
}