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
|
// Copyright (C) 2019-2024 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
//go:build !windows
// +build !windows
package dnssec
import (
"fmt"
"io"
"os"
"time"
"github.com/miekg/dns"
)
const defaultConfigFile = "/etc/resolv.conf"
// SystemConfig return list of DNS servers and timeout from /etc/resolv.conf
func SystemConfig() (servers []ResolverAddress, timeout time.Duration, err error) {
var f *os.File
f, err = os.Open(defaultConfigFile)
if err != nil {
return
}
defer func() {
localErr := f.Close()
if err == nil {
err = localErr
}
}()
return systemConfig(f)
}
func systemConfig(configFile io.Reader) (servers []ResolverAddress, timeout time.Duration, err error) {
if configFile == nil {
err = fmt.Errorf("empty config reader")
return
}
cc, err := dns.ClientConfigFromReader(configFile)
if err != nil {
return
}
for _, addr := range cc.Servers {
servers = append(servers, MakeResolverAddress(addr, cc.Port))
}
timeout = DefaultTimeout
if cc.Timeout != 0 && len(servers) > 0 {
timeout = time.Duration(cc.Timeout) * time.Second
}
if timeout > maxTimeout {
timeout = maxTimeout
}
return
}
|
