DoQ first draft. Still need to think about connection reusability

internal/protocols/doq/doq.go

@@ -1,3 +1,117 @@
 package doq
 
-// DoQ (DNS over QUIC) resolver implementation
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"encoding/binary"
+	"fmt"
+	"io"
+	"os"
+
+	"github.com/afonsofrancof/sdns-perf/internal/protocols/do53"
+	"github.com/miekg/dns"
+	"github.com/quic-go/quic-go"
+)
+
+type DoQClient struct {
+	target        string
+	keyLogFile    *os.File
+	tlsConfig     *tls.Config
+}
+
+func New(target string) (*DoQClient, error) {
+	keyLogFile, err := os.OpenFile(
+		"tls-key-log.txt",
+		os.O_APPEND|os.O_CREATE|os.O_WRONLY,
+		0600,
+	)
+	if err != nil {
+		return nil, fmt.Errorf("failed opening key log file: %v", err)
+	}
+
+	tlsConfig := &tls.Config{
+		// FIX: Actually check the domain name
+		InsecureSkipVerify: true,
+		MinVersion:         tls.VersionTLS13,
+		KeyLogWriter:       keyLogFile,
+		NextProtos:         []string{"doq"},
+	}
+
+	return &DoQClient{
+		target:        target,
+		keyLogFile:    keyLogFile,
+		tlsConfig:     tlsConfig,
+	}, nil
+}
+
+func (c *DoQClient) Close() {
+	if c.keyLogFile != nil {
+		c.keyLogFile.Close()
+	}
+}
+
+func (c *DoQClient) Query(domain, queryType string, dnssec bool) error {
+	quicConn, err := quic.DialAddr(context.Background(), c.target, c.tlsConfig, &quic.Config{})
+	if err != nil {
+		return fmt.Errorf("failed to establish QUIC connection: %v", err)
+	}
+	defer quicConn.CloseWithError(0, "")
+
+	DNSMessage, err := do53.NewDNSMessage(domain, queryType)
+	if err != nil {
+		return err
+	}
+
+	quicStream, err := quicConn.OpenStreamSync(context.Background())
+	if err != nil {
+		return fmt.Errorf("failed to opening QUIC stream: %v", err)
+	}
+	defer quicStream.Close()
+
+	var lengthPrefixedMessage bytes.Buffer
+	err = binary.Write(&lengthPrefixedMessage, binary.BigEndian, uint16(len(DNSMessage)))
+	if err != nil {
+		return fmt.Errorf("failed to write message length: %v", err)
+	}
+	_, err = lengthPrefixedMessage.Write(DNSMessage)
+	if err != nil {
+		return fmt.Errorf("failed to write DNS message: %v", err)
+	}
+
+	_, err = quicStream.Write(lengthPrefixedMessage.Bytes())
+	if err != nil {
+		return fmt.Errorf("failed writing to QUIC stream: %v", err)
+	}
+
+	lengthBuf := make([]byte, 2)
+	_, err = io.ReadFull(quicStream, lengthBuf)
+	if err != nil {
+		return fmt.Errorf("failed reading response length: %v", err)
+	}
+
+	messageLength := binary.BigEndian.Uint16(lengthBuf)
+	if messageLength == 0 {
+		return fmt.Errorf("received zero-length message")
+	}
+
+	responseBuf := make([]byte, messageLength)
+	_, err = io.ReadFull(quicStream, responseBuf)
+	if err != nil {
+		return fmt.Errorf("failed reading response data: %v", err)
+	}
+
+	recvMsg := new(dns.Msg)
+	err = recvMsg.Unpack(responseBuf)
+	if err != nil {
+		return fmt.Errorf("failed to parse DNS response: %v", err)
+	}
+
+	// TODO: Check if the response had no errors or TD bit set
+
+	for _, answer := range recvMsg.Answer {
+		fmt.Println(answer.String())
+	}
+
+	return nil
+}