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97 lines
1.5 KiB
Go
97 lines
1.5 KiB
Go
package main
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import (
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//"fmt"
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"errors"
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"github.com/miekg/dns"
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"net"
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"time"
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)
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var ip_region []*net.IPNet
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type res struct {
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m *dns.Msg
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err error
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}
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func _query(m *dns.Msg, s *UpstreamServer, c chan *res) {
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res1 := make(chan *res)
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go query_one(s, m, res1)
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select {
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case r := <-res1:
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c <- r
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case <-time.After(600 * time.Millisecond):
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c <- &res{err: errors.New("timed out")}
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}
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}
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func query(m *dns.Msg) *dns.Msg {
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resch := make(chan *res, len(DefaultServer))
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for _, s := range DefaultServer {
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go _query(m, s, resch)
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}
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delayed := []*dns.Msg{}
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slen := len(DefaultServer)
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for i := 0; i < slen; i++ {
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r := <-resch
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r1 := *r
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if r1.err != nil {
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logger.Error("error %s\n", r1.err.Error())
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continue
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}
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// drop the result with no error but has an empty result
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if r1.m.Rcode == dns.RcodeSuccess &&
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len(r1.m.Answer) == 0 {
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continue
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}
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// drop blacklist
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if in_blacklist(r1.m) {
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continue
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}
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// check ip region
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if answer_in_region(r1.m, ip_region) {
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return r1.m
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} else {
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delayed = append(delayed, r1.m)
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}
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}
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if len(delayed) == 0 {
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logger.Error("empty delayed list")
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return nil
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}
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// return first ok result
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for _, m1 := range delayed {
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if m1.Rcode == dns.RcodeSuccess {
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return m1
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}
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}
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// return NXDOMAIN result
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for _, m1 := range delayed {
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if m1.Rcode == dns.RcodeNameError {
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return m1
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}
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}
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// errror
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return nil
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}
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func query_one(srv *UpstreamServer, m *dns.Msg, ch chan *res) {
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m1, err := srv.query(m)
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select {
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case ch <- &res{m1, err}:
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}
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}
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