Added basic DoT support

internal/protocols/dot/dot.go

@@ -1,3 +1,145 @@
 package dot
 
-// DoT (DNS over TLS) resolver implementation
+import (
+	"crypto/tls"
+	"fmt"
+	"net"
+	"os"
+
+	"github.com/afonsofrancof/sdns-perf/internal/protocols/do53"
+	"golang.org/x/net/dns/dnsmessage"
+)
+
+func Run(domain, queryType, server string, dnssec bool) error {
+
+	DNSMessage, err := do53.MakeDNSMessage(domain, queryType)
+	if err != nil {
+		return err
+	}
+
+	// Step 1 - Establish a TCP Connection
+	tcpConn, err := net.Dial("tcp", server)
+	if err != nil {
+		return fmt.Errorf("failed to establish TCP connection: %v", err)
+	}
+	defer tcpConn.Close()
+
+	// Step 2 - Upgrade it to a TLS Connection
+
+	// Temporary keylog file to allow traffic inspection
+	keyLogFile, err := os.OpenFile(
+		"tls-key-log.txt",
+		os.O_APPEND|os.O_CREATE|os.O_WRONLY,
+		0600,
+	)
+	if err != nil {
+		return fmt.Errorf("failed opening key log file: %v", err)
+	}
+	defer keyLogFile.Close()
+
+	tlsConfig := &tls.Config{
+		InsecureSkipVerify: true,
+		MinVersion:         tls.VersionTLS12,
+		KeyLogWriter:       keyLogFile,
+	}
+
+	tlsConn := tls.Client(tcpConn, tlsConfig)
+	err = tlsConn.Handshake()
+	if err != nil {
+		return fmt.Errorf("failed to execute the TLS handshake: %v", err)
+	}
+	defer tlsConn.Close()
+
+	// Before sending the DNS message over TLS, prepend the 2-byte length field
+	lengthPrefixedMessage := make([]byte, len(DNSMessage)+2)
+	lengthPrefixedMessage[0] = byte(len(DNSMessage) >> 8)   // High byte
+	lengthPrefixedMessage[1] = byte(len(DNSMessage) & 0xFF) // Low byte
+	copy(lengthPrefixedMessage[2:], DNSMessage)
+
+	_, err = tlsConn.Write(lengthPrefixedMessage)
+	if err != nil {
+		return fmt.Errorf("failed writing TLS request: %v", err)
+	}
+
+	// Read the 2-byte length prefix
+	lengthBuf := make([]byte, 2)
+	_, err = tlsConn.Read(lengthBuf)
+	if err != nil {
+		return fmt.Errorf("failed reading response length: %v", err)
+	}
+
+	// Calculate the message length from the 2-byte prefix
+	messageLength := int(lengthBuf[0])<<8 | int(lengthBuf[1])
+
+	responseBuf := make([]byte, messageLength)
+	n, err := tlsConn.Read(responseBuf)
+	if err != nil {
+		return fmt.Errorf("failed reading TLS response: %v", err)
+	}
+
+	// Parse the response
+	var parser dnsmessage.Parser
+	header, err := parser.Start(responseBuf[:n])
+	if err != nil {
+		return fmt.Errorf("failed to parse DNS response: %v", err)
+	}
+
+	fmt.Printf("DNS Response Header:\n")
+	fmt.Printf("  ID: %d\n", header.ID)
+	fmt.Printf("  Response: %v\n", header.Response)
+	fmt.Printf("  RCode: %v\n", header.RCode)
+
+	// Skip all questions before reading answers
+	err = parser.SkipAllQuestions()
+	if err != nil {
+		return fmt.Errorf("failed to skip questions: %v", err)
+	}
+
+	// Parse answers
+	fmt.Printf("\nAnswers:\n")
+	answers, err := parser.AllAnswers()
+
+	for i, answer := range answers {
+
+		if err != nil {
+			return fmt.Errorf("failed to parse answer %d: %v", i, err)
+		}
+
+		fmt.Printf("  Answer %d:\n", i+1)
+		fmt.Printf("    Name: %v\n", answer.Header.Name)
+		fmt.Printf("    Type: %v\n", answer.Header.Type)
+		fmt.Printf("    TTL: %v seconds\n", answer.Header.TTL)
+
+		// Handle different record types
+		switch answer.Header.Type {
+		case dnsmessage.TypeA:
+			if r, ok := answer.Body.(*dnsmessage.AResource); ok {
+				fmt.Printf("    IPv4: %d.%d.%d.%d\n", r.A[0], r.A[1], r.A[2], r.A[3])
+			}
+		case dnsmessage.TypeAAAA:
+			if r, ok := answer.Body.(*dnsmessage.AAAAResource); ok {
+				ip := r.AAAA
+				fmt.Printf("    IPv6: %02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x:%02x%02x\n",
+					ip[0], ip[1], ip[2], ip[3], ip[4], ip[5], ip[6], ip[7],
+					ip[8], ip[9], ip[10], ip[11], ip[12], ip[13], ip[14], ip[15])
+			}
+		case dnsmessage.TypeCNAME:
+			if r, ok := answer.Body.(*dnsmessage.CNAMEResource); ok {
+				fmt.Printf("    CNAME: %v\n", r.CNAME)
+			}
+		case dnsmessage.TypeMX:
+			if r, ok := answer.Body.(*dnsmessage.MXResource); ok {
+				fmt.Printf("    Preference: %v\n", r.Pref)
+				fmt.Printf("    MX: %v\n", r.MX)
+			}
+		case dnsmessage.TypeTXT:
+			if r, ok := answer.Body.(*dnsmessage.TXTResource); ok {
+				fmt.Printf("    TXT: %v\n", r.TXT)
+			}
+		default:
+			fmt.Printf("    [Unsupported record type]\n")
+		}
+	}
+
+	return nil
+}