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SnowPearDNS.go
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SnowPearDNS.go
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package main
import (
"encoding/json"
"flag"
"fmt"
"io/ioutil"
"log"
"math/rand"
"net"
"net/http"
"os"
"path/filepath"
"runtime"
"strconv"
"strings"
"time"
"github.com/arryboom/go-hostsparser"
"github.com/miekg/dns"
"github.com/muesli/cache2go"
)
var (
//server_url string = "http://119.29.29.29/d?dn=%s"
server_url string = "https://doh.pub/dns-query?name=%s&type=%s"
version string = Version.String()
dnsAcache = cache2go.Cache("DNACACHE")
dnsCcache = cache2go.Cache("DNCCACHE")
hostsflag *bool
lchostsflag *string
cache_time = 60 * 60 * 24 * time.Second
)
type DOH_Answer struct {
Name string
Thattype int `json:"type"`
TTL int
Expires string
Data string
}
/*{
"name": "www.baidu.com.",
"type": 5,
"TTL": 1200,
"Expires": "Wed, 15 Dec 2021 00:18:23 UTC",
"data": "www.a.shifen.com."
}*/
type DOH_Request struct {
NAME string
Thetype int `json:"type"`
}
type DOH_Response struct {
Status int
TC bool `json:"-"`
RD bool `json:"-"`
RA bool `json:"-"`
AD bool `json:"-"`
CD bool `json:"-"`
Question []DOH_Request `json:"-"`
Answer []DOH_Answer
edns_client_subnet string `json:"-"`
}
func init_dohip() bool {
var initurl string = "http://119.29.29.29/d?dn=doh.pub"
//current resolve to 175.24.219.66,may change.
var c_buf string
r, err := http.Get(initurl)
if err != nil {
fmt.Println(err)
return false
}
defer r.Body.Close()
buf, err := ioutil.ReadAll(r.Body)
if err != nil {
fmt.Println(err)
return false
}
c_buf = byteString(buf)
ips := strings.Split(c_buf, ";")
randomIndex := rand.Intn(len(ips))
pick := ips[randomIndex]
if pick != "" {
dnsAcache.Add("doh.pub.", 0, pick)
fmt.Println(curtime() + " ###Init DOH resolve success.###")
return true
}
return false
}
func get_a(domain string) []string {
var c_buf string
var cnamesign bool = false
ip := []string{}
dncres, dncerr := dnsAcache.Value(domain)
if dncerr == nil {
c_buf = dncres.Data().(string)
} else {
url := fmt.Sprintf(server_url, domain, "A")
r, err := http.Get(url)
if err != nil {
return []string{}
}
defer r.Body.Close()
buf, err := ioutil.ReadAll(r.Body)
if err != nil {
return []string{}
}
var resp DOH_Response
if err := json.Unmarshal(buf, &resp); err != nil {
fmt.Println(err)
return []string{}
} else {
if resp.Status != 0 && resp.Status != 3 || resp.Answer == nil {
fmt.Println(err)
return []string{}
}
}
for _, vl := range resp.Answer {
if vl.Thattype == 1 {
if c_buf != "" {
c_buf = c_buf + ";" + vl.Data
} else {
c_buf = vl.Data
}
}
if vl.Thattype == 5 {
dntres, dnterr := dnsCcache.Value(domain)
if dnterr == nil {
var tempc string = dntres.Data().(string)
tempc = tempc + ";" + vl.Data
dnsCcache.Delete(domain)
dnsCcache.Add(domain, cache_time, tempc)
} else {
dnsCcache.Add(domain, cache_time, vl.Data)
}
cnamesign = true
}
}
dnsAcache.Add(domain, cache_time, c_buf)
}
if c_buf == "" && cnamesign {
dntres, dnterr := dnsCcache.Value(domain)
if dnterr != nil {
return []string{}
}
var tempc string = dntres.Data().(string)
c_buf = tempc
dnsAcache.Add(domain, cache_time, c_buf)
}
ips := strings.Split(c_buf, ";")
for _, ii := range ips {
ip = append(ip, string(ii))
}
return ip
}
func get_cname(domain string) []string {
var c_buf string
ip := []string{}
dncres, dncerr := dnsCcache.Value(domain)
if dncerr == nil {
c_buf = dncres.Data().(string)
} else {
url := fmt.Sprintf(server_url, domain, "CNAME")
r, err := http.Get(url)
if err != nil {
return []string{}
}
defer r.Body.Close()
buf, err := ioutil.ReadAll(r.Body)
if err != nil {
return []string{}
}
var resp DOH_Response
if err := json.Unmarshal(buf, &resp); err != nil {
fmt.Println(err)
return []string{}
} else {
if resp.Status != 0 && resp.Status != 3 || resp.Answer == nil {
fmt.Println(err)
return []string{}
}
}
for _, vl := range resp.Answer {
if vl.Thattype == 5 {
if c_buf != "" {
c_buf = c_buf + ";" + vl.Data
} else {
c_buf = vl.Data
}
}
if vl.Thattype == 1 {
dntres, dnterr := dnsAcache.Value(domain)
if dnterr == nil {
var tempc string = dntres.Data().(string)
tempc = tempc + ";" + vl.Data
dnsAcache.Delete(domain)
dnsAcache.Add(domain, cache_time, tempc)
} else {
dnsAcache.Add(domain, cache_time, vl.Data)
}
}
}
dnsCcache.Add(domain, cache_time, c_buf)
}
ips := strings.Split(c_buf, ";")
for _, ii := range ips {
ip = append(ip, string(ii))
}
return ip
}
func curtime() string {
return time.Now().Format("2006-01-02 15:04:05.000")
}
func handleRoot(w dns.ResponseWriter, r *dns.Msg) {
if r.Question[0].Qtype == dns.TypeA {
domain := r.Question[0].Name
fmt.Println(curtime() + " DnsReq_A: " + domain)
ip := get_a(domain)
if len(ip) == 0 {
dns.HandleFailed(w, r)
fmt.Println(curtime() + fmt.Sprintf(" Failed to get DNS record: %s", domain))
return
}
msg := new(dns.Msg)
msg.SetReply(r)
msg_cname := new(dns.Msg)
msg_cname.SetReply(r)
var cname_sign bool = false
var a_sign bool = false
for _, ii := range ip {
///
if net.ParseIP(ii) == nil && ii != "" {
s := fmt.Sprintf("%s 3600 IN CNAME %s",
dns.Fqdn(domain), ii)
rr, _ := dns.NewRR(s)
msg_cname.Answer = append(msg.Answer, rr)
msg_cname.Rcode = 3
cname_sign = true
}
s := fmt.Sprintf("%s 3600 IN A %s",
dns.Fqdn(domain), ii)
rr, _ := dns.NewRR(s)
msg.Answer = append(msg.Answer, rr)
a_sign = true
}
if a_sign {
w.WriteMsg(msg)
}
if cname_sign {
w.WriteMsg(msg_cname)
}
return
}
if r.Question[0].Qtype == dns.TypeCNAME {
domain := r.Question[0].Name
fmt.Println(curtime() + " DnsReq_CNAME: " + domain)
ip := get_cname(domain)
if len(ip) == 0 {
dns.HandleFailed(w, r)
fmt.Println(curtime() + fmt.Sprintf(" Failed to get DNS record: %s", domain))
return
}
msg := new(dns.Msg)
msg.SetReply(r)
for _, ii := range ip {
s := fmt.Sprintf("%s 3600 IN CNAME %s",
dns.Fqdn(domain), ii)
rr, _ := dns.NewRR(s)
msg.Answer = append(msg.Answer, rr)
}
w.WriteMsg(msg)
return
}
dns.HandleFailed(w, r)
return
}
func byteString(p []byte) string {
for i := 0; i < len(p); i++ {
if p[i] == 0 {
return string(p[0:i])
}
}
return string(p)
}
func add_localhosts() {
if *hostsflag {
fmt.Println("loading Hosts file...")
hostsMap, err := hostsparser.ParseHosts(hostsparser.ReadHostsFile())
if err != nil {
return
}
for k, v := range hostsMap {
dnsAcache.Add(k+".", 0, v)
}
}
}
func ReadAll(filePth string) ([]byte, error) {
f, err := os.Open(filePth)
if err != nil {
return nil, err
}
return ioutil.ReadAll(f)
}
func FileExist(path string) bool {
_, err := os.Lstat(path)
return !os.IsNotExist(err)
}
func parse_localdnsrecord() (int, bool) {
if *lchostsflag != "" {
hostsMap, err := hostsparser.ParseHosts(ReadAll(*lchostsflag))
if err != nil {
return 0, false
}
rcdcount := 0
for k, v := range hostsMap {
rcdcount = rcdcount + 1
dnsAcache.Add(k+".", 0, v)
}
return rcdcount, true
} else {
path, err := os.Executable()
if err != nil {
log.Fatal(err)
}
dir := filepath.Dir(path)
// dir=dir+"/"
slash := "/"
switch runtime.GOOS {
case "windows":
slash = "\\"
}
confpath := dir + slash + "spdhosts.conf"
if FileExist(confpath) {
fmt.Println("Loading DNS records conf data from " + confpath)
hostsMap, err := hostsparser.ParseHosts(ReadAll(confpath))
if err != nil {
return 0, false
}
rcdcount := 0
for k, v := range hostsMap {
rcdcount = rcdcount + 1
dnsAcache.Add(k+".", 0, v)
}
return rcdcount, true
} else {
return 0, false
}
}
}
func main() {
fmt.Println("SnowPearDNS version: ", version)
fmt.Println("https://github.com/arryboom/SnowPearDNS")
hostsflag = flag.Bool("hosts", false, "using local hosts file,default false.(Conflict with -c)")
lchostsflag = flag.String("c", "", "conf file path,default Current Directory spdhosts.conf")
flag.Parse()
add_localhosts()
if *hostsflag && *lchostsflag != "" {
fmt.Println("-hosts and -c enabled at the same time,ignore -c option")
} else {
ct, sig := parse_localdnsrecord()
if sig {
fmt.Println("Loaded " + strconv.Itoa(ct) + " dns records in conf.")
}
}
fmt.Println("Start Dns Server Now...")
if !(init_dohip()) {
fmt.Println("Failed to init DOH server's DNS resolve,pls check your network connection.")
}
dns.HandleFunc(".", handleRoot)
err := dns.ListenAndServe("0.0.0.0:53", "udp", nil)
if err != nil {
log.Fatal(err)
fmt.Println("Failed to bind UDP port 53,please check your appliction and network.")
}
}