Not finished stuff

2025-05-01 12:34:30 +01:00
parent bf190b2396
commit 2e0042153a
6 changed files with 673 additions and 443 deletions
--- a/internal/protocols/do53/do53.go
+++ b/internal/protocols/do53/do53.go
@@ -2,64 +2,128 @@ package do53

 import (
 	"fmt"
+	"log"
 	"net"
+	"sync"

 	"github.com/miekg/dns"
 )

-type Do53Client struct {
-	udpConn *net.UDPConn
+type Config struct {
+	HostAndPort string
+	DNSSEC      bool
 }

-func New(dest string) (*Do53Client, error) {
+type Client struct {
+	udpAddr *net.UDPAddr
+	conn    *net.UDPConn

-	udpAddr, err := net.ResolveUDPAddr("udp", dest)
-	if err != nil {
-		return nil, fmt.Errorf("failed to resolve UDP address: %v", err)
-	}
+	responseChannels map[uint16]chan *dns.Msg
+	responseMutex          *sync.Mutex

-	udpConn, err := net.DialUDP("udp", nil, udpAddr)
-	if err != nil {
-		return nil, fmt.Errorf("failed to dial UDP connection: %v", err)
-	}
-	return &Do53Client{udpConn: udpConn}, nil
+	config Config
 }

-func (c *Do53Client) Close() {
-	if c.udpConn != nil {
-		c.udpConn.Close()
+func New(config Config) (*Client, error) {
+	udpAddr, err := net.ResolveUDPAddr("udp", config.HostAndPort)
+	if err != nil {
+		return nil, fmt.Errorf("do53: failed to resolve UDP address %q: %w", config.HostAndPort, err)
+	}
+
+	conn, err := net.DialUDP("udp", nil, udpAddr)
+	if err != nil {
+		return nil, fmt.Errorf("do53: failed to dial UDP connection to %s: %w", config.HostAndPort, err)
+	}
+
+	responseChannels := map[uint16]chan *dns.Msg{}
+	rcMutex := new(sync.Mutex)
+
+	client := &Client{
+		udpAddr:          udpAddr,
+		conn:             conn,
+		responseChannels: responseChannels,
+		responseMutex:          rcMutex,
+		config:           config,
+	}
+
+	go client.receiveLoop()
+
+	return client, nil
+}
+
+func (c *Client) Close() {
+	if c.conn != nil {
+		c.conn.Close()
+		c.conn = nil
 	}
 }

-func (c *Do53Client) Query(domain, queryType, dest string, dnssec bool) error {
+func (c *Client) receiveLoop() {

-	message, err := NewDNSMessage(domain, queryType)
-	if err != nil {
-		return err
+	buffer := make([]byte, dns.MaxMsgSize)
+
+	for {
+		// Reads one UDP Datagram
+		n, err := c.conn.Read(buffer)
+		if err != nil {
+			log.Printf("do53: failed to read DNS response: %s", err.Error())
+		}
+
+		recvMsg := new(dns.Msg)
+		err = recvMsg.Unpack(buffer[:n])
+		if err != nil {
+			log.Printf("do53: failed to unpack DNS response: %s", err.Error())
+			continue
+		}
+
+		c.responseMutex.Lock()
+		respChan, ok := c.responseChannels[recvMsg.Id]
+		delete(c.responseChannels, recvMsg.Id)
+		c.responseMutex.Unlock()
+
+		if ok {
+			respChan <- recvMsg
+		} else {
+			log.Printf("Receiver: Received DNS response for unknown or already processed msg ID: %v\n", recvMsg.Id)
+		}
 	}

-	_, err = c.udpConn.Write(message)
-	if err != nil {
-		return fmt.Errorf("failed to send DNS query: %v", err)
-	}
-
-	buf := make([]byte, 4096)
-	n, err := c.udpConn.Read(buf)
-	if err != nil {
-		return fmt.Errorf("failed to read DNS response: %v", err)
-	}
-
-	recvMsg := new(dns.Msg)
-	err = recvMsg.Unpack(buf[:n])
-	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
+}
+
+func (c *Client) Query(domain string, queryType uint16) (*dns.Msg, error) {
+
+	msg := new(dns.Msg)
+	msg.SetQuestion(dns.Fqdn(domain), queryType)
+	msg.Id = dns.Id()
+	msg.RecursionDesired = true
+
+	if c.config.DNSSEC {
+		msg.SetEdns0(4096, true)
+	}
+
+	respChan := make(chan *dns.Msg)
+
+	c.responseMutex.Lock()
+	c.responseChannels[msg.Id] = respChan
+	c.responseMutex.Unlock()
+
+	packedMsg, err := msg.Pack()
+	if err != nil {
+		c.responseMutex.Lock()
+		delete(c.responseChannels, msg.Id)
+		c.responseMutex.Unlock()
+		return nil, fmt.Errorf("do53: failed to pack DNS message: %w", err)
+	}
+
+	_, err = c.conn.Write(packedMsg)
+	if err != nil {
+		c.responseMutex.Lock()
+		delete(c.responseChannels, msg.Id)
+		c.responseMutex.Unlock()
+		return nil, fmt.Errorf("do53: failed to send DNS query: %w", err)
+	}
+
+	recvMsg := <-respChan
+
+	return recvMsg, nil
 }
--- a/internal/protocols/doh/doh.go
+++ b/internal/protocols/doh/doh.go
@@ -1,121 +1,125 @@
 package doh

 import (
-	"bufio"
 	"bytes"
 	"crypto/tls"
+	"errors"
 	"fmt"
 	"io"
 	"net"
 	"net/http"
-	"os"
+	"net/url"
+	"strings"

-	"github.com/afonsofrancof/sdns-perf/internal/protocols/do53"
 	"github.com/miekg/dns"
 )

-type DoHClient struct {
-	tcpConn    *net.TCPConn
-	tlsConn    *tls.Conn
-	keyLogFile *os.File
-	target     string
-	path       string
-	proxy      string
+const dnsMessageContentType = "application/dns-message"
+
+type Config struct {
+	Host   string
+	Port   string
+	Path   string
+	DNSSEC bool
 }

-func New(target, path, proxy string) (*DoHClient, error) {
+type Client struct {
+	httpClient  *http.Client
+	upstreamURL *url.URL
+	config      Config
+}

-	tcpAddr, err := net.ResolveTCPAddr("tcp", target)
-	if err != nil {
-		return nil, fmt.Errorf("failed to resolve TCP address: %v", err)
+func New(config Config) (*Client, error) {
+	if config.Host == "" || config.Port == "" || config.Path == "" {
+		fmt.Printf("%v,%v,%v", config.Host,config.Port,config.Path)
+		return nil, errors.New("doh: host, port, and path must not be empty")
 	}

-	tcpConn, err := net.DialTCP("tcp", nil, tcpAddr)
-	if err != nil {
-		return nil, fmt.Errorf("failed to establish TCP connection: %v", err)
+	if !strings.HasPrefix(config.Path, "/") {
+		config.Path = "/" + config.Path
 	}
+	rawURL := "https://" + net.JoinHostPort(config.Host, config.Port) + config.Path

-	keyLogFile, err := os.OpenFile(
-		"tls-key-log.txt",
-		os.O_APPEND|os.O_CREATE|os.O_WRONLY,
-		0600,
-	)
+	parsedURL, err := url.Parse(rawURL)
 	if err != nil {
-		return nil, fmt.Errorf("failed opening key log file: %v", err)
+		return nil, fmt.Errorf("doh: failed to parse constructed URL %q: %w", rawURL, err)
 	}

 	tlsConfig := &tls.Config{
-		// FIX: Actually check the domain name
-		InsecureSkipVerify: true,
-		MinVersion:         tls.VersionTLS12,
-		KeyLogWriter:       keyLogFile,
+		ServerName: config.Host,
+		MinVersion: tls.VersionTLS12,
 	}

-	tlsConn := tls.Client(tcpConn, tlsConfig)
-	err = tlsConn.Handshake()
-	if err != nil {
-		return nil, fmt.Errorf("failed to execute the TLS handshake: %v", err)
+	transport := &http.Transport{
+		TLSClientConfig:   tlsConfig,
+		ForceAttemptHTTP2: true,
 	}

-	return &DoHClient{tcpConn: tcpConn, keyLogFile: keyLogFile, tlsConn: tlsConn, target: target, path: path, proxy: proxy}, err
+	httpClient := &http.Client{
+		Transport: transport,
+	}

+	return &Client{
+		httpClient:  httpClient,
+		upstreamURL: parsedURL,
+		config:      config,
+	}, nil
 }

-func (c *DoHClient) Close() {
-	if c.tcpConn != nil {
-		c.tcpConn.Close()
-	}
-	if c.keyLogFile != nil {
-		c.keyLogFile.Close()
-	}
-	if c.tlsConn != nil {
-		c.tlsConn.Close()
-	}
+// Close cleans up idle connections held by the underlying HTTP transport.
+func (c *Client) Close() {
+	c.httpClient.CloseIdleConnections()
 }

-func (c *DoHClient) Query(domain, queryType string, dnssec bool) error {
+func (c *Client) Query(domain string, queryType uint16) (*dns.Msg, error) {
+	msg := new(dns.Msg)
+	msg.SetQuestion(dns.Fqdn(domain), queryType)
+	msg.Id = dns.Id()
+	msg.RecursionDesired = true

-	DNSMessage, err := do53.NewDNSMessage(domain, queryType)
+	if c.config.DNSSEC {
+		msg.SetEdns0(4096, true)
+	}
+
+	packedMsg, err := msg.Pack()
 	if err != nil {
-		return err
+		return nil, fmt.Errorf("doh: failed to pack DNS message: %w", err)
 	}

-	httpReq, err := http.NewRequest("POST", "https://"+c.target+"/"+c.path, bytes.NewBuffer(DNSMessage))
+	httpReq, err := http.NewRequest("POST", c.upstreamURL.String(), bytes.NewReader(packedMsg))
 	if err != nil {
-		return fmt.Errorf("failed to create HTTP request: %v", err)
+		return nil, fmt.Errorf("doh: failed to create HTTP request object: %w", err)
 	}
-	httpReq.Header.Add("Content-Type", "application/dns-message")
-	httpReq.Header.Set("Accept", "application/dns-message")

-	err = httpReq.Write(c.tlsConn)
+	httpReq.Header.Set("User-Agent", "sdns-perf")
+	httpReq.Header.Set("Content-Type", dnsMessageContentType)
+	httpReq.Header.Set("Accept", dnsMessageContentType)
+
+	httpResp, err := c.httpClient.Do(httpReq)
 	if err != nil {
-		return fmt.Errorf("failed writing HTTP request: %v", err)
+		return nil, fmt.Errorf("doh: failed executing HTTP request to %s: %w", c.upstreamURL.Host, err)
+	}
+	defer httpResp.Body.Close()
+
+	if httpResp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("doh: received non-200 HTTP status from %s: %s", c.upstreamURL.Host, httpResp.Status)
 	}

-	reader := bufio.NewReader(c.tlsConn)
-	resp, err := http.ReadResponse(reader, httpReq)
+	if ct := httpResp.Header.Get("Content-Type"); ct != dnsMessageContentType {
+		return nil, fmt.Errorf("doh: unexpected Content-Type from %s: got %q, want %q", c.upstreamURL.Host, ct, dnsMessageContentType)
+	}
+
+	responseBody, err := io.ReadAll(httpResp.Body)
 	if err != nil {
-		return fmt.Errorf("failed reading HTTP response: %v", err)
-	}
-	defer resp.Body.Close()
-
-	responseBody := make([]byte, 4096)
-	n, err := resp.Body.Read(responseBody)
-	if err != nil && err != io.EOF {
-		return fmt.Errorf("failed reading response body: %v", err)
+		return nil, fmt.Errorf("doh: failed reading response body from %s: %w", c.upstreamURL.Host, err)
 	}

+	// Unpack the DNS message
 	recvMsg := new(dns.Msg)
-	err = recvMsg.Unpack(responseBody[:n])
+	err = recvMsg.Unpack(responseBody)
 	if err != nil {
-		return fmt.Errorf("failed to parse DNS response: %v", err)
+		return nil, fmt.Errorf("doh: failed to unpack DNS response from %s: %w", c.upstreamURL.Host, err)
 	}

-	// TODO: Check if the response had no errors or TD bit set
-
-	for _, answer := range recvMsg.Answer {
-		fmt.Println(answer.String())
-	}
-
-	return nil
+	return recvMsg, nil
 }
--- a/internal/protocols/doq/doq.go
+++ b/internal/protocols/doq/doq.go
@@ -7,87 +7,144 @@ import (
 	"encoding/binary"
 	"fmt"
 	"io"
+	"net"
 	"os"
+	"time"

 	"github.com/afonsofrancof/sdns-perf/internal/protocols/do53"
 	"github.com/miekg/dns"
 	"github.com/quic-go/quic-go"
 )

-type DoQClient struct {
-	target        string
+type Client struct {
+	targetAddr    *net.UDPAddr
 	keyLogFile    *os.File
 	tlsConfig     *tls.Config
+	udpConn       *net.UDPConn
+	quicConn      quic.Connection
+	quicTransport *quic.Transport
+	quicConfig    *quic.Config
 }

-func New(target string) (*DoQClient, error) {
+func New(target string) (*Client, 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)
+		return nil, fmt.Errorf("failed opening key log file: %w", err)
 	}

 	tlsConfig := &tls.Config{
 		// FIX: Actually check the domain name
 		InsecureSkipVerify: true,
 		MinVersion:         tls.VersionTLS13,
+		ClientSessionCache: tls.NewLRUClientSessionCache(100),
 		KeyLogWriter:       keyLogFile,
 		NextProtos:         []string{"doq"},
 	}

-	return &DoQClient{
-		target:        target,
+	udpAddr, err := net.ResolveUDPAddr("udp", "0.0.0.0:6000")
+	if err != nil {
+		return nil, fmt.Errorf("failed to resolve target address: %w", err)
+	}
+	targetAddr, err := net.ResolveUDPAddr("udp", target)
+	if err != nil {
+		return nil, err
+	}
+	udpConn, err := net.ListenUDP("udp", udpAddr)
+	if err != nil {
+		return nil, fmt.Errorf("failed to connect to target address: %w", err)
+	}
+
+	quicTransport := quic.Transport{
+		Conn: udpConn,
+	}
+
+	quicConfig := quic.Config{
+		// Use the default value of 30 seconds
+		MaxIdleTimeout: 30 * time.Second,
+	}
+
+	return &Client{
+		targetAddr:    targetAddr,
 		keyLogFile:    keyLogFile,
 		tlsConfig:     tlsConfig,
+		udpConn:       udpConn,
+		quicConn:      nil,
+		quicTransport: &quicTransport,
+		quicConfig:    &quicConfig,
 	}, nil
 }

-func (c *DoQClient) Close() {
+func (c *Client) Close() {
 	if c.keyLogFile != nil {
 		c.keyLogFile.Close()
 	}
+	if c.udpConn != nil {
+		c.udpConn.Close()
+	}
 }

-func (c *DoQClient) Query(domain, queryType string, dnssec bool) error {
-	quicConn, err := quic.DialAddr(context.Background(), c.target, c.tlsConfig, &quic.Config{})
+func (c *Client) OpenConnection() error {
+	quicConn, err := c.quicTransport.DialEarly(context.Background(), c.targetAddr, c.tlsConfig, c.quicConfig)
 	if err != nil {
-		return fmt.Errorf("failed to establish QUIC connection: %v", err)
+		return err
+	}
+
+	c.quicConn = quicConn
+	return nil
+}
+
+func (c *Client) Query(domain, queryType string, dnssec bool) error {
+
+	if c.quicConn == nil {
+		err := c.OpenConnection()
+		if err != nil {
+			return err
+		}
 	}
-	defer quicConn.CloseWithError(0, "")

 	DNSMessage, err := do53.NewDNSMessage(domain, queryType)
 	if err != nil {
 		return err
 	}

-	quicStream, err := quicConn.OpenStreamSync(context.Background())
+	var quicStream quic.Stream
+	quicStream, err = c.quicConn.OpenStream()
 	if err != nil {
-		return fmt.Errorf("failed to opening QUIC stream: %v", err)
+		err = c.OpenConnection()
+		if err != nil {
+			return err
+		}
+		quicStream, err = c.quicConn.OpenStream()
+		if err != nil {
+			return 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)
+		return fmt.Errorf("failed to write message length: %w", err)
 	}
 	_, err = lengthPrefixedMessage.Write(DNSMessage)
 	if err != nil {
-		return fmt.Errorf("failed to write DNS message: %v", err)
+		return fmt.Errorf("failed to write DNS message: %w", err)
 	}

 	_, err = quicStream.Write(lengthPrefixedMessage.Bytes())
 	if err != nil {
-		return fmt.Errorf("failed writing to QUIC stream: %v", err)
+		return fmt.Errorf("failed writing to QUIC stream: %w", err)
 	}
+	// Indicate that no further data will be written from this side
+	quicStream.Close()

 	lengthBuf := make([]byte, 2)
 	_, err = io.ReadFull(quicStream, lengthBuf)
 	if err != nil {
-		return fmt.Errorf("failed reading response length: %v", err)
+		return fmt.Errorf("failed reading response length: %w", err)
 	}

 	messageLength := binary.BigEndian.Uint16(lengthBuf)
@@ -98,17 +155,18 @@ func (c *DoQClient) Query(domain, queryType string, dnssec bool) error {
 	responseBuf := make([]byte, messageLength)
 	_, err = io.ReadFull(quicStream, responseBuf)
 	if err != nil {
-		return fmt.Errorf("failed reading response data: %v", err)
+		return fmt.Errorf("failed reading response data: %w", err)
 	}

 	recvMsg := new(dns.Msg)
 	err = recvMsg.Unpack(responseBuf)
 	if err != nil {
-		return fmt.Errorf("failed to parse DNS response: %v", err)
+		return fmt.Errorf("failed to parse DNS response: %w", err)
 	}

 	// TODO: Check if the response had no errors or TD bit set

+	fmt.Println(c.quicConn.ConnectionState().Used0RTT)
 	for _, answer := range recvMsg.Answer {
 		fmt.Println(answer.String())
 	}
--- a/internal/protocols/dot/dot.go
+++ b/internal/protocols/dot/dot.go
@@ -1,122 +1,161 @@
 package dot

 import (
-	"bytes"
+	"context"
 	"crypto/tls"
 	"encoding/binary"
 	"fmt"
 	"io"
+	"log"
 	"net"
 	"os"
+	"sync"
+	"time"

-	"github.com/afonsofrancof/sdns-perf/internal/protocols/do53"
 	"github.com/miekg/dns"
 )

-type DoTClient struct {
-	tcpConn    *net.TCPConn
-	tlsConn    *tls.Conn
-	keyLogFile *os.File
+type Config struct {
+	Host   string
+	Port   string
+	DNSSEC bool
+	Debug  bool
 }

-func New(target string) (*DoTClient, error) {
+type Client struct {
+	config Config

-	tcpAddr, err := net.ResolveTCPAddr("tcp", target)
+	serverAddr *net.TCPAddr
+
+	tcpConn    *net.TCPConn
+	tlsConn    *tls.Conn
+	tlsConfig  *tls.Config
+	keyLogFile *os.File
+
+	sendChannel chan *dns.Msg
+
+	responseChannels map[uint16]chan *dns.Msg
+	responseMutex    *sync.Mutex
+}
+
+func New(config Config) (*Client, error) {
+	serverAddr, err := net.ResolveTCPAddr("tcp", net.JoinHostPort(config.Host, config.Port))
 	if err != nil {
-		return nil, fmt.Errorf("failed to resolve TCP address: %v", err)
+		return nil, fmt.Errorf("dot: failed to resolve TCP address %q: %w", config.Host, err)
 	}

-	tcpConn, err := net.DialTCP("tcp", nil, tcpAddr)
-	if err != nil {
-		return nil, fmt.Errorf("failed to establish TCP connection: %v", err)
-	}
-
-	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)
+	var keyLogFile *os.File
+	if config.Debug {
+		keyLogFile, err = os.OpenFile(
+			"tls-key-log.txt",
+			os.O_APPEND|os.O_CREATE|os.O_WRONLY,
+			0600,
+		)
+		if err != nil {
+			log.Printf("dot: failed opening TLS key log file: %v", err)
+			keyLogFile = nil
+		}
 	}

 	tlsConfig := &tls.Config{
-		InsecureSkipVerify: true,
+		ServerName:         serverAddr.IP.String(),
 		MinVersion:         tls.VersionTLS12,
 		KeyLogWriter:       keyLogFile,
+		ClientSessionCache: tls.NewLRUClientSessionCache(100),
 	}

-	tlsConn := tls.Client(tcpConn, tlsConfig)
-	err = tlsConn.Handshake()
-	if err != nil {
-		return nil, fmt.Errorf("failed to execute the TLS handshake: %v", err)
+	client := &Client{
+		config:     config,
+		serverAddr: serverAddr,
+		tlsConfig:  tlsConfig,
+		keyLogFile: keyLogFile,
 	}

-	return &DoTClient{tcpConn: tcpConn, tlsConn: tlsConn, keyLogFile: keyLogFile}, nil
+	go client.receiveLoop()
+
+	return client, nil
 }

-func (c *DoTClient) Close() {
-	if c.tcpConn != nil {
-		c.tcpConn.Close()
-	}
+func (c *Client) Close() {
 	if c.tlsConn != nil {
 		c.tlsConn.Close()
+		c.tlsConn = nil
 	}
+
+	if c.tcpConn != nil {
+		c.tcpConn.Close()
+		c.tcpConn = nil
+	}
+
 	if c.keyLogFile != nil {
 		c.keyLogFile.Close()
+		c.keyLogFile = nil
 	}
 }

-func (c *DoTClient) Query(domain, queryType, target string, dnssec bool) error {
+func (c *Client) receiveLoop() {

-	DNSMessage, err := do53.NewDNSMessage(domain, queryType)
+	lengthBuffer := make([]byte, 2)
+	buffer := make([]byte, dns.MaxMsgSize)
+
+	for {
+		msgSize, err := io.ReadFull(c.tlsConn, lengthBuffer)
+		if err != nil {
+			log.Printf("doh: failed to read the DNS message's size: %s", err.Error())
+			// FIX: HANDLE RECONNECTION
+		}
+		n, err := io.ReadFull(c.tlsConn, buffer[:msgSize])
+		if err != nil {
+			log.Printf("doh: failed to read the DNS message: %s", err.Error())
+			// FIX: HANDLE RECONNECTION
+		}
+
+		recvMsg := new(dns.Msg)
+		err = recvMsg.Unpack(buffer[:n])
+		if err != nil {
+			log.Printf("do53: failed to unpack DNS response: %s", err.Error())
+			continue
+		}
+
+		c.responseMutex.Lock()
+		respChan, ok := c.responseChannels[recvMsg.Id]
+		delete(c.responseChannels, recvMsg.Id)
+		c.responseMutex.Unlock()
+
+		if ok {
+			respChan <- recvMsg
+		} else {
+			log.Printf("Receiver: Received DNS response for unknown or already processed msg ID: %v\n", recvMsg.Id)
+		}
+
+	}
+
+}
+
+func (c *Client) connect(ctx context.Context) error {
+	tcpConn, err := net.DialTCP("tcp", nil, c.serverAddr)
 	if err != nil {
-		return err
+		return fmt.Errorf("dot: failed to establish TCP connection: %w", err)
 	}

-	var lengthPrefixedMessage bytes.Buffer
-	err = binary.Write(&lengthPrefixedMessage, binary.BigEndian, uint16(len(DNSMessage)))
+	c.tcpConn.SetKeepAlive(true)
+	c.tcpConn.SetKeepAlivePeriod(1 * time.Minute)
+
+	tlsConn := tls.Client(c.tcpConn, c.tlsConfig)
+	err = tlsConn.HandshakeContext(ctx)
 	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)
+		c.tcpConn.Close()
+		c.tcpConn = nil
+		return fmt.Errorf("dot: failed to execute the TLS handshake: %w", err)
 	}

-	_, err = c.tlsConn.Write(lengthPrefixedMessage.Bytes())
-	if err != nil {
-		return fmt.Errorf("failed writing TLS request: %v", err)
-	}
+	c.tlsConn = tlsConn

-	lengthBuf := make([]byte, 2)
-	_, err = io.ReadFull(c.tlsConn, 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(c.tlsConn, responseBuf)
-	if err != nil {
-		return fmt.Errorf("failed reading TLS response: %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())
-	}
+	log.Println("dot: TCP/TLS connection established successfully.")

 	return nil
 }
+
+func (c *Client) Query(domain string, queryType uint16) (*dns.Msg, error) {
+	//TODO
+}