[Minor] Add another helper for rdns

contrib/librdns/rdns.h

@@ -359,6 +359,13 @@ const char *rdns_strtype (enum rdns_request_type type);
  */
 enum rdns_request_type rdns_type_fromstr (const char *str);
 
+/**
+ * Parse string and return error code
+ * @param str
+ * @return
+ */
+enum dns_rcode rdns_rcode_fromstr (const char *str);
+
 /**
  * Increase refcount for a request
  * @param req

contrib/librdns/util.c

@@ -289,6 +289,51 @@ rdns_type_fromstr (const char *str)
 	return -1;
 }
 
+enum dns_rcode
+rdns_rcode_fromstr (const char *str)
+{
+	if (str) {
+		if (strcmp (str, "noerror") == 0) {
+			return RDNS_RC_NOERROR;
+		}
+		else if (strcmp (str, "formerr") == 0) {
+			return RDNS_RC_FORMERR;
+		}
+		else if (strcmp (str, "servfail") == 0) {
+			return RDNS_RC_SERVFAIL;
+		}
+		else if (strcmp (str, "notimp") == 0) {
+			return RDNS_RC_NOTIMP;
+		}
+		else if (strcmp (str, "yxdomain") == 0) {
+			return RDNS_RC_YXDOMAIN;
+		}
+		else if (strcmp (str, "yxrrset") == 0) {
+			return RDNS_RC_YXRRSET;
+		}
+		else if (strcmp (str, "nxrrset") == 0) {
+			return RDNS_RC_NXRRSET;
+		}
+		else if (strcmp (str, "notauth") == 0) {
+			return RDNS_RC_NOTAUTH;
+		}
+		else if (strcmp (str, "notzone") == 0) {
+			return RDNS_RC_NOTZONE;
+		}
+		else if (strcmp (str, "timeout") == 0) {
+			return RDNS_RC_TIMEOUT;
+		}
+		else if (strcmp (str, "neterr") == 0) {
+			return RDNS_RC_NETERR;
+		}
+		else if (strcmp (str, "norec") == 0) {
+			return RDNS_RC_NOREC;
+		}
+	}
+
+	return -1;
+}
+
 uint16_t
 rdns_permutor_generate_id (void)
 {