the project structure modified and new features added

utils/dns_utils.go

@@ -27,6 +27,15 @@ type DomainInfo struct {
 	NSList map[string][]string
 }
 
+type SVCBRecord struct {
+	Target string            `json:"target"`
+	Data   map[string]string `json:"value"`
+}
+
+type SVCBResponse struct {
+	Records []SVCBRecord `json:"records"`
+}
+
 func (e *WrongAnswerError) Error() string {
 	return fmt.Sprintf("Wrong Answer: %s", e.Message)
 }
@@ -39,11 +48,7 @@ func QuestionMaker(domain string, qclass uint16, qtype uint16) *dns.Question {
 // build a dns query message
 func QueryMaker(query QueryStruct) *dns.Msg {
 	msg := new(dns.Msg)
-	if query.Id < 0 {
-		msg.Id = dns.Id()
-	} else {
-		msg.Id = query.Id
-	}
+	msg.Id = query.Id
 	msg.RecursionDesired = query.RD
 
 	var query_name string
@@ -155,3 +160,58 @@ func SendVersionQuery(ip string) (*dns.Msg, error) {
 
 	return res, err
 }
+
+func SendSVCBQuery(ip string, domain string) (*dns.Msg, error) {
+	addr := ip + ":53"
+	query := QueryStruct{Id: dns.Id(), Qname: dns.Fqdn(domain), RD: true, Qtype: dns.TypeSVCB}
+	m := QueryMaker(query)
+
+	res, err := dns.Exchange(m, addr)
+
+	return res, err
+}
+
+func toSVCBKEY(key dns.SVCBKey) string {
+	switch key {
+	case dns.SVCB_MANDATORY:
+		return "mandatory"
+	case dns.SVCB_ALPN:
+		return "alpn"
+	case dns.SVCB_NO_DEFAULT_ALPN:
+		return "no_default_alpn"
+	case dns.SVCB_PORT:
+		return "port"
+	case dns.SVCB_IPV4HINT:
+		return "ipv4_hint"
+	case dns.SVCB_ECHCONFIG:
+		return "ech_config"
+	case dns.SVCB_IPV6HINT:
+		return "ipv6_hint"
+	case dns.SVCB_DOHPATH:
+		return "doh_path"
+	default:
+		return "unknown"
+	}
+}
+
+func ParseSVCBResponse(msg *dns.Msg) (SVCBResponse, error) {
+	response := SVCBResponse{Records: make([]SVCBRecord, 0)}
+	if len(msg.Answer) > 0 {
+		for _, rr := range msg.Answer {
+			if svcb, ok := rr.(*dns.SVCB); ok {
+				record := SVCBRecord{Data: make(map[string]string)}
+				record.Target = svcb.Target
+				for _, kv := range svcb.Value {
+					key := toSVCBKEY(kv.Key())
+					value := kv.String()
+					record.Data[key] = value
+				}
+				response.Records = append(response.Records, record)
+			}
+		}
+	}
+	if len(response.Records) > 0 {
+		return response, nil
+	}
+	return response, &WrongAnswerError{Message: "no valid SVCB records"}
+}