diff --git a/cmd/resolver/main.go b/cmd/resolver/main.go index 2731df6..6127d83 100644 --- a/cmd/resolver/main.go +++ b/cmd/resolver/main.go @@ -5,13 +5,14 @@ import ( "github.com/afonsofrancof/sdns-perf/internal/protocols/do53" "github.com/afonsofrancof/sdns-perf/internal/protocols/doh" + "github.com/afonsofrancof/sdns-perf/internal/protocols/dot" "github.com/alecthomas/kong" ) type CommonFlags struct { DomainName string `help:"Domain name to resolve" arg:"" required:""` QueryType string `help:"Query type" enum:"A,AAAA,MX,TXT,NS,CNAME,SOA,PTR" default:"A"` - Server string `help:"DNS server to use"` + Server string `help:"DNS server to use" required:""` DNSSEC bool `help:"Enable DNSSEC validation"` } @@ -52,8 +53,7 @@ func (c *DoHCmd) Run() error { } func (c *DoTCmd) Run() error { - // TODO: Implement DoT query - return nil + return dot.Run(c.DomainName, c.QueryType, c.Server, c.DNSSEC) } func (c *DoQCmd) Run() error { diff --git a/internal/protocols/dot/dot.go b/internal/protocols/dot/dot.go index d1f5d05..eaf6ebd 100644 --- a/internal/protocols/dot/dot.go +++ b/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 +}