1 files changed, 128 insertions, 0 deletions
diff --git a/tools/dnsd/main.go b/tools/dnsd/main.go
new file mode 100644
index 0000000..314c86d
--- /dev/null
+++ b/tools/dnsd/main.go
@@ -0,0 +1,128 @@
+package main
+
+import (
+	"bufio"
+	"flag"
+	"log"
+	"net/http"
+
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/Xe/x/internal"
+	"github.com/miekg/dns"
+	"github.com/mmikulicic/stringlist"
+)
+
+var (
+	port   = flag.String("port", "53", "UDP port to listen on for DNS")
+	server = flag.String("forward-server", "1.1.1.1:53", "forward DNS server")
+
+	zoneURLs = stringlist.Flag("zone-url", "DNS zonefiles to load")
+)
+
+var (
+	defaultZoneURLS = []string{
+		"https://xena.greedo.xeserv.us/files/akua.zone",
+		"https://xena.greedo.xeserv.us/files/adblock.zone",
+	}
+)
+
+func main() {
+	internal.HandleStartup()
+
+	if len(*zoneURLs) == 0 {
+		*zoneURLs = defaultZoneURLS
+	}
+
+	for _, zurl := range *zoneURLs {
+		log.Printf("conf: -zone-url=%s", zurl)
+	}
+	log.Printf("conf: -port=%s", *port)
+	log.Printf("conf: -forward-server=%s", *server)
+
+	rrs := []dns.RR{}
+
+	for _, zurl := range *zoneURLs {
+		resp, err := http.Get(zurl)
+		if err != nil {
+			panic(err)
+		}
+
+		reader := bufio.NewReaderSize(resp.Body, 2048)
+
+		var i int
+		zp := dns.NewZoneParser(reader, "", zurl)
+		for rr, ok := zp.Next(); ok; rr, ok = zp.Next() {
+			rrs = append(rrs, rr)
+			i++
+		}
+
+		if zp.Err() != nil {
+			panic(zp.Err())
+		}
+
+		resp.Body.Close()
+
+		log.Printf("%s: %d records", zurl, i)
+	}
+
+	dns.HandleFunc(".", func(w dns.ResponseWriter, r *dns.Msg) {
+		m := new(dns.Msg)
+		m.SetReply(r)
+		m.Authoritative = true
+
+		for _, q := range r.Question {
+			answers := []dns.RR{}
+			for _, rr := range rrs {
+				rh := rr.Header()
+
+				if rh.Rrtype == dns.TypeCNAME && q.Name == rh.Name {
+					answers = append(answers, rr)
+
+					for _, a := range resolver("127.0.0.1:"+*port, rr.(*dns.CNAME).Target, q.Qtype) {
+						answers = append(answers, a)
+					}
+				}
+
+				if q.Name == rh.Name && q.Qtype == rh.Rrtype && q.Qclass == rh.Class {
+					answers = append(answers, rr)
+				}
+			}
+			if len(answers) == 0 && *server != "" {
+				for _, a := range resolver(*server, q.Name, q.Qtype) {
+					answers = append(answers, a)
+				}
+			}
+			for _, a := range answers {
+				m.Answer = append(m.Answer, a)
+			}
+		}
+		w.WriteMsg(m)
+	})
+
+	go func() {
+		srv := &dns.Server{Addr: ":" + *port, Net: "udp"}
+		if err := srv.ListenAndServe(); err != nil {
+			log.Fatalf("Failed to set udp listener %s\n", err.Error())
+		}
+	}()
+
+	sig := make(chan os.Signal)
+	signal.Notify(sig, syscall.SIGINT, syscall.SIGTERM)
+	s := <-sig
+	log.Fatalf("Signal (%v) received, stopping\n", s)
+}
+
+func resolver(server, fqdn string, r_type uint16) []dns.RR {
+	m1 := new(dns.Msg)
+	m1.Id = dns.Id()
+	m1.SetQuestion(fqdn, r_type)
+
+	in, err := dns.Exchange(m1, server)
+	if err == nil {
+		return in.Answer
+	}
+	return []dns.RR{}
+}