62 lines
1.1 KiB
Go
62 lines
1.1 KiB
Go
package main
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import (
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"log"
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"strings"
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"github.com/miekg/dns"
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)
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const upstream = "1.1.1.1:53"
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var blocklist = []string{
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"x.com.",
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"twitter.com.",
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"example.com.",
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}
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func isBlocked(domain string) bool {
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domain = strings.ToLower(domain)
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for _, blocked := range blocklist {
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// Check exact match or subdomain
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if domain == blocked || strings.HasSuffix(domain, "."+blocked) {
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return true
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}
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}
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return false
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}
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func handleDNS(w dns.ResponseWriter, r *dns.Msg) {
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m := new(dns.Msg)
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m.SetReply(r)
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c := new(dns.Client)
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for _, q := range r.Question {
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log.Printf("question: %s", q.Name)
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if isBlocked(q.Name) {
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res, err := dns.NewRR(q.Name + " 60 IN A 0.0.0.0")
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if err != nil {
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log.Fatal(err)
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}
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m.Answer = append(m.Answer, res)
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} else {
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req := new(dns.Msg)
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req.Question = append(req.Question, q)
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res, _, err := c.Exchange(req, upstream)
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if err != nil {
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log.Fatal(err)
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}
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m.Answer = append(m.Answer, res.Answer...)
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}
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}
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w.WriteMsg(m)
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}
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func main() {
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dns.HandleFunc(".", handleDNS)
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server := &dns.Server{Addr: ":53", Net: "udp"}
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log.Println("Starting DNS Server on :53")
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log.Fatal(server.ListenAndServe())
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}
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