implement questions in dns payload

src/core/packetgen/payload.go

@@ -78,18 +78,49 @@ func buildICMPV4Packet(c ICMPV4PacketConfig) *layers.ICMPv4 {
 	}
 }
 
+// DNSQuestion wraps a single request (question) within a DNS query.
+type DNSQuestion struct {
+	Name  string
+	Type  layers.DNSType
+	Class layers.DNSClass
+}
+
 type DNSPacketConfig struct {
-	ID      uint16
-	Qr      bool
-	OpCode  uint8
-	QDCount uint16
+	ID     uint16
+	Qr     bool
+	OpCode uint8
+
+	AA bool  // Authoritative answer
+	TC bool  // Truncated
+	RD bool  // Recursion desired
+	RA bool  // Recursion available
+	Z  uint8 // Reserved for future use
+
+	ResponseCode uint8
+	QDCount      *uint16 // Number of questions to expect
+
+	// Entries
+	Questions []DNSQuestion
 }
 
 func buildDNSPacket(c DNSPacketConfig) *layers.DNS {
+	questions := make([]layers.DNSQuestion, 0, len(c.Questions))
+	for _, question := range c.Questions {
+		questions = append(questions, layers.DNSQuestion{Name: []byte(question.Name), Type: question.Type, Class: question.Class})
+	}
+
 	return &layers.DNS{
-		ID:      c.ID,
-		QR:      c.Qr,
-		OpCode:  layers.DNSOpCode(c.OpCode),
-		QDCount: c.QDCount,
+		ID:     c.ID,
+		QR:     c.Qr,
+		OpCode: layers.DNSOpCode(c.OpCode),
+
+		AA: c.AA,
+		TC: c.TC,
+		RD: c.RD,
+		RA: c.RA,
+		Z:  c.Z,
+
+		QDCount:   utils.NonNilOrDefault(c.QDCount, uint16(len(c.Questions))),
+		Questions: questions,
 	}
 }

src/core/packetgen/serialization_test.go

@@ -1,12 +1,14 @@
 package packetgen
 
 import (
+	"bytes"
 	"encoding/binary"
 	"fmt"
 	"testing"
 
 	"github.com/google/gopacket"
 	"github.com/google/gopacket/layers"
+	"github.com/miekg/dns"
 	"go.uber.org/zap"
 
 	"github.com/Arriven/db1000n/src/utils"
@@ -133,3 +135,58 @@ func extractPayload(p gopacket.Packet, c map[string]any) error {
 
 	return nil
 }
+
+func TestDNS(t *testing.T) {
+	t.Parallel()
+
+	configTPL := map[string]any{
+		"payload": map[string]any{
+			"type": "dns",
+			"data": map[string]any{
+				"id":      1234,
+				"op_code": 0,
+				"rd":      true,
+				"questions": []map[string]any{
+					{
+						"name":  "google.com",
+						"type":  "1",
+						"class": "1",
+					},
+				},
+			},
+		},
+	}
+
+	logger := zap.NewExample()
+	config := templates.ParseAndExecuteMapStruct(logger, configTPL, nil)
+
+	var packetConfig PacketConfig
+	if err := utils.Decode(config, &packetConfig); err != nil {
+		t.Fatal(err)
+	}
+
+	logger.Debug("deserialized packet config", zap.Any("packet", packetConfig))
+
+	packet, err := packetConfig.Build()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	buf := gopacket.NewSerializeBuffer()
+	if err = packet.Serialize(buf); err != nil {
+		t.Fatal(err)
+	}
+
+	question := new(dns.Msg).
+		SetQuestion(dns.Fqdn("google.com"), 1)
+	question.Id = 1234
+
+	out, err := question.Pack()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Equal(buf.Bytes(), out) {
+		t.Fatal(fmt.Errorf("not equal %v to %v", buf.Bytes(), out))
+	}
+}