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
|
// dns utils
package utils
import (
"github.com/miekg/dns"
)
type DNSOptions struct {
Domain string
RD bool
Qclass uint16
Qtype uint16
EDNS bool
}
// build the question section of a dns packet
func questionMaker(domain string, qclass uint16, qtype uint16) *dns.Question {
return &dns.Question{Name: dns.Fqdn(domain), Qtype: qtype, Qclass: qclass}
}
// build a specific query message
func queryMaker(domain string, rd bool, qclass uint16, qtype uint16, edns bool) *dns.Msg {
msg := new(dns.Msg)
msg.Id = dns.Id()
msg.RecursionDesired = rd
msg.Question = make([]dns.Question, 1)
msg.Question[0] = *questionMaker(domain, qclass, qtype)
if edns {
msg = msg.SetEdns0(1232, false)
}
return msg
}
// query and receive the response
// addr must contain dest port
// func DNSQuery(addr string, domain string, rd bool, qclass uint16, qtype uint16, edns bool) (*dns.Msg, error) {
func DNSQuery(addr string, opt DNSOptions) (*dns.Msg, error) {
if opt.Qclass == 0 {
opt.Qclass = 1
}
if opt.Qtype == 0 {
opt.Qtype = 1
}
msg := queryMaker(opt.Domain, opt.RD, opt.Qclass, opt.Qtype, opt.EDNS)
res, err := dns.Exchange(msg, addr)
return res, err
}
func AsyncDNSQuery(addr string, domain string, rd bool, qclass uint16, qtype uint16, edns bool) error {
msg := queryMaker(domain, rd, qclass, qtype, edns)
client := dns.Client{Net: "udp"}
conn, err := client.Dial(addr)
if err != nil {
return err
}
defer conn.Close()
err = conn.WriteMsg(msg)
if err != nil {
return err
}
return nil
}
|
