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google_front.go
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google_front.go
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package dnsclient
import (
"encoding/json"
"io/ioutil"
"log"
"net/http"
"strconv"
"time"
"github.com/miekg/dns"
)
// GoogleFrontDNS is a Client instance resolving using Googles DNS-over-HTTPS service,
// fronted using www.google.com
type GoogleFrontDNS struct {
BaseURL string
}
// Lookup performs a DNS lookup using Google
func (c *GoogleFrontDNS) Lookup(name string, rType uint16) Response {
client := http.Client{
Timeout: time.Second * 20,
}
req, err := http.NewRequest("GET", c.BaseURL, nil)
if err != nil {
log.Fatal(err)
}
// Update the Host client header to dns.google.com
// Ref: https://twitter.com/vysecurity/status/1058947074392125440
req.Host = "dns.google.com"
q := req.URL.Query()
q.Add("name", name)
q.Add("type", strconv.Itoa(int(rType)))
q.Add("cd", "false") // ignore DNSSEC
// TODO: add random_padding
req.URL.RawQuery = q.Encode()
res, err := client.Do(req)
if err != nil {
log.Fatal(err)
}
body, err := ioutil.ReadAll(res.Body)
if err != nil {
log.Fatal(err)
}
dnsRequestResponse := requestResponse{}
err = json.Unmarshal(body, &dnsRequestResponse)
if err != nil {
log.Fatal(err)
}
fout := Response{}
if len(dnsRequestResponse.Answer) <= 0 {
return fout
}
fout.TTL = dnsRequestResponse.Answer[0].TTL
fout.Data = dnsRequestResponse.Answer[0].Data
fout.Status = dns.RcodeToString[dnsRequestResponse.Status]
return fout
}