From 3f2c5e507f91280dc48837725387ace4899189e1 Mon Sep 17 00:00:00 2001
From: Jonni Liljamo <jonni@liljamo.com>
Date: Wed, 9 Oct 2024 13:29:22 +0300
Subject: [PATCH] feat: initial NS and SOA responses

---
 internal/dns/query.go | 63 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/internal/dns/query.go b/internal/dns/query.go
index b0f839f..26a4ffa 100644
--- a/internal/dns/query.go
+++ b/internal/dns/query.go
@@ -12,6 +12,7 @@ import (
 	"net"
 	"strings"
 
+	"git.src.quest/~liljamo/felu/internal/config"
 	"git.src.quest/~liljamo/felu/internal/db"
 	"github.com/miekg/dns"
 )
@@ -27,6 +28,12 @@ func parseQuery(m *dns.Msg, r *dns.Msg) {
 		switch q.Qtype {
 		case dns.TypeA:
 			handleARecord(&q, m, r)
+		case dns.TypeNS:
+			handleNSRecord(&q, m, r)
+		case dns.TypeSOA:
+			handleSOARecord(&q, m, r)
+		default:
+			m.SetRcode(r, dns.RcodeNotImplemented)
 		}
 
 		slog.Info("Responding to Query",
@@ -51,3 +58,59 @@ func handleARecord(q *dns.Question, m *dns.Msg, r *dns.Msg) {
 		m.SetRcode(r, dns.RcodeNameError)
 	}
 }
+
+func handleNSRecord(q *dns.Question, m *dns.Msg, r *dns.Msg) {
+	ns := &dns.NS{
+		Hdr: dns.RR_Header{Name: q.Name, Rrtype: dns.TypeNS, Class: dns.ClassINET, Ttl: 0},
+		Ns:  dns.Fqdn(config.FeluConfig.DDNSDomain),
+	}
+
+	// "Root" DDNS domain NS.
+	if q.Name == dns.Fqdn(config.FeluConfig.DDNSDomain) {
+		m.Answer = append(m.Answer, ns)
+		return
+	}
+
+	if index := strings.IndexByte(q.Name, '.'); index >= 0 {
+		// FIXME: other way of checking that the domain exists
+		_, err := db.FetchDomainARecord(strings.ToLower(q.Name[:index]))
+		if err != nil {
+			m.SetRcode(r, dns.RcodeNameError)
+		} else {
+			m.Answer = append(m.Answer, ns)
+		}
+	} else {
+		m.SetRcode(r, dns.RcodeNameError)
+	}
+}
+
+func handleSOARecord(q *dns.Question, m *dns.Msg, r *dns.Msg) {
+	soa := &dns.SOA{
+		Hdr:     dns.RR_Header{Name: q.Name, Rrtype: dns.TypeSOA, Class: dns.ClassINET, Ttl: 0},
+		Ns:      dns.Fqdn(config.FeluConfig.DDNSDomain),
+		Mbox:    dns.Fqdn(config.FeluConfig.SOAEmail),
+		Serial:  2024100301,
+		Refresh: 86400,
+		Retry:   7200,
+		Expire:  3600000,
+		Minttl:  172800,
+	}
+
+	// "Root" DDNS domain SOA.
+	if q.Name == dns.Fqdn(config.FeluConfig.DDNSDomain) {
+		m.Answer = append(m.Answer, soa)
+		return
+	}
+
+	if index := strings.IndexByte(q.Name, '.'); index >= 0 {
+		// FIXME: other way of checking that the domain exists
+		_, err := db.FetchDomainARecord(strings.ToLower(q.Name[:index]))
+		if err != nil {
+			m.SetRcode(r, dns.RcodeNameError)
+		} else {
+			m.Answer = append(m.Answer, soa)
+		}
+	} else {
+		m.SetRcode(r, dns.RcodeNameError)
+	}
+}
-- 
2.44.1