-
Notifications
You must be signed in to change notification settings - Fork 324
/
ttl.go
83 lines (75 loc) · 2.17 KB
/
ttl.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
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
// Copyright (C) 2020-2021, IrineSistiana
//
// This file is part of mosdns.
//
// mosdns is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// mosdns is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
package dnsutils
import "github.com/miekg/dns"
// GetMinimalTTL returns the minimal ttl of this msg.
// If msg m has no record, it returns 0.
func GetMinimalTTL(m *dns.Msg) uint32 {
minTTL := ^uint32(0)
hasRecord := false
for _, section := range [...][]dns.RR{m.Answer, m.Ns, m.Extra} {
for _, rr := range section {
if rr.Header().Rrtype == dns.TypeOPT {
continue // opt record ttl is not ttl.
}
hasRecord = true
ttl := rr.Header().Ttl
if ttl < minTTL {
minTTL = ttl
}
}
}
if !hasRecord { // no ttl applied
return 0
}
return minTTL
}
// SetTTL updates all records' ttl to ttl, except opt record.
func SetTTL(m *dns.Msg, ttl uint32) {
for _, section := range [...][]dns.RR{m.Answer, m.Ns, m.Extra} {
for _, rr := range section {
if rr.Header().Rrtype == dns.TypeOPT {
continue // opt record ttl is not ttl.
}
rr.Header().Ttl = ttl
}
}
}
func ApplyMaximumTTL(m *dns.Msg, ttl uint32) {
applyTTL(m, ttl, true)
}
func ApplyMinimalTTL(m *dns.Msg, ttl uint32) {
applyTTL(m, ttl, false)
}
func applyTTL(m *dns.Msg, ttl uint32, maximum bool) {
for _, section := range [...][]dns.RR{m.Answer, m.Ns, m.Extra} {
for _, rr := range section {
if rr.Header().Rrtype == dns.TypeOPT {
continue // opt record ttl is not ttl.
}
if maximum {
if rr.Header().Ttl > ttl {
rr.Header().Ttl = ttl
}
} else {
if rr.Header().Ttl < ttl {
rr.Header().Ttl = ttl
}
}
}
}
}