From 97c847ab1cf02b8d29178e870d5c4b039f10a9f5 Mon Sep 17 00:00:00 2001
From: Miek Gieben <miek@miek.nl>
Date: Tue, 1 Mar 2011 15:40:50 +0100
Subject: [PATCH] make it a real simple nameserver

---
 _examples/ns/ns.go | 102 +++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 95 insertions(+), 7 deletions(-)

diff --git a/_examples/ns/ns.go b/_examples/ns/ns.go
index 5dd3f72f..47b61d7d 100644
--- a/_examples/ns/ns.go
+++ b/_examples/ns/ns.go
@@ -3,11 +3,15 @@ package main
 import (
 	"os"
 	"dns"
+        "net"
 	"fmt"
 	"flag"
-	"json"
+        "os/signal"
+//	"json"
 )
 
+var counter int
+
 func main() {
 //	var zone *string = flag.String("zone", "", "The zone to serve")
 	flag.Usage = func() {
@@ -32,11 +36,95 @@ func main() {
 	t.Txt = "Een antwoord"
 	m.Answer[0] = t
 
-	json, err := json.Marshal(m)
-	if err != nil {
-		fmt.Printf("Err: %s", err.String())
-                os.Exit(1)
-	}
-        fmt.Printf("%v", string(json))
+        errchan := make(chan os.Error)
+        go udp("127.0.0.1:8054", errchan)
+        go tcp("127.0.0.1:8054", errchan)
 
+        forever:
+                for {
+                        select {
+                        case e := <-errchan:
+                                fmt.Printf("Error received, stopping: %s\n", e.String())
+                                break forever
+                        case <-signal.Incoming:
+                                fmt.Printf("Signal received, stopping\n")
+                                break forever
+                        }
+                }
+        close(errchan)
+        fmt.Printf("Queries answered: %d\n", counter)
 }
+
+func tcp(addr string, e chan os.Error) {
+        a, err := net.ResolveTCPAddr(addr)
+        if err != nil {
+                e <- err
+        }
+        l, err := net.ListenTCP("tcp", a)
+        if err != nil {
+                e <- err
+        }
+        err = dns.ServeTCP(l, replyTCP)
+        e <- err
+        return
+}
+
+func udp(addr string, e chan os.Error) {
+        a, err := net.ResolveUDPAddr(addr)
+        if err != nil {
+                e <- err
+        }
+        l, err := net.ListenUDP("udp", a)
+        if err != nil {
+                e <- err
+        }
+        err = dns.ServeUDP(l, replyUDP)
+        e <- err
+        return
+}
+
+
+func createpkg(id uint16, tcp bool, remove net.Addr) []byte {
+        m := new(dns.Msg)
+        m.MsgHdr.Id = id
+        m.MsgHdr.Authoritative = true
+        m.MsgHdr.AuthenticatedData = false
+        m.MsgHdr.RecursionAvailable = true
+        m.MsgHdr.Response = true
+        m.MsgHdr.Opcode = dns.OpcodeQuery
+        m.MsgHdr.Rcode = dns.RcodeSuccess
+        m.Question = make([]dns.Question, 1)
+        m.Question[0] = dns.Question{"miek.nl.", dns.TypeTXT, dns.ClassINET}
+        m.Answer = make([]dns.RR, 1)
+        t := new(dns.RR_TXT)
+        t.Hdr = dns.RR_Header{Name: "miek.nl.", Rrtype: dns.TypeTXT, Class: dns.ClassINET, Ttl: 3600}
+        if tcp {
+                t.Txt = "Dit is iets anders TCP"
+        } else {
+                t.Txt = "Dit is iets anders UDP"
+        }
+        m.Answer[0] = t
+        out, _ := m.Pack()
+        return out
+}
+
+func replyUDP(c *net.UDPConn, a net.Addr, in *dns.Msg) {
+        if in.MsgHdr.Response == true {
+                // Uh... answering to an response??
+                // dont think so
+                return
+        }
+        out := createpkg(in.MsgHdr.Id, false, a)
+        dns.SendUDP(out, c, a)
+        counter++
+}
+
+func replyTCP(c *net.TCPConn, a net.Addr, in *dns.Msg) {
+        if in.MsgHdr.Response == true {
+                return
+        }
+        out := createpkg(in.MsgHdr.Id, true, a)
+        dns.SendTCP(out, c, a)
+        counter++
+}
+