ntp: add functions for parsing extension fields

ntp_ext.h

@@ -0,0 +1,37 @@
+/*
+  chronyd/chronyc - Programs for keeping computer clocks accurate.
+
+ **********************************************************************
+ * Copyright (C) Miroslav Lichvar  2019
+ * 
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ * 
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * 
+ **********************************************************************
+
+  =======================================================================
+
+  Header file for NTP extension fields
+  */
+
+#ifndef GOT_NTP_EXT_H
+#define GOT_NTP_EXT_H
+
+#include "ntp.h"
+
+extern int NEF_ParseSingleField(unsigned char *buffer, int buffer_length, int start,
+                                int *length, int *type, void **body, int *body_length);
+extern int NEF_ParseField(NTP_Packet *packet, int packet_length, int start,
+                          int *length, int *type, void **body, int *body_length);
+
+#endif