There are a few small additions to the protocol to make it

easier to use in mixed environments:

- Add three new members to the request structure:

  - a filename specification
  - a database type specification
  - a system byte prder specification

  These allow the client to ask the server for a particular type of
  database (Berkeley DB hash/btree/recno, GNU GDBM, dbm, ndbm, etc...)
  and get back a meaningful error if the server doesn't support it.
  The byte order spec is needed if the database type is byte order
  sensntive. You don't, for example, want to read an ndbm database
  from a big endian machine on a little endian machine (the ndbm code
  will explode). The filename spec lets the client handle things like
  ndbm which uses two seperate files per database (foo.dir and foo.pag).
  The client can ask for each half, one at a time.

- Add a list of database types and byte order values. Each list has
  a wildcard 'ANY' entry which lets the client ask for whatever the
  server supports. (XFR_ENDIAN_ANY is useful with the Berkeley DB hash
  method for instance, since it isn't byte order sensitive.)

- Add two newserver failure codes: XFR_DB_TYPE_MISMATCH and
  XFR_DB_ENDIAN_MISMATCH. The server uses these to tell the client
  that it doesn't support the requested type/byte order.

These changes were made at the suggestion of Thorsten Kukuk, the
current maintainer of the Linux ypserv distribution. This allows
Linux and FreeBSD NIS servers to use the same ypxfrd protocol and
avoid accidentally exchanging incompatible map files.

include/rpcsvc/ypxfrd.x

@@ -29,7 +29,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- *	$Id: ypxfrd.x,v 1.8 1996/06/03 20:17:04 wpaul Exp $
+ *	$Id: ypxfrd.x,v 1.9 1996/07/02 00:35:36 wpaul Exp $
  */
 
 /*
@@ -68,7 +68,7 @@
 
 #ifndef RPC_HDR
 %#ifndef lint
-%static const char rcsid[] = "$Id: ypxfrd.x,v 1.8 1996/06/03 20:17:04 wpaul Exp $";
+%static const char rcsid[] = "$Id: ypxfrd.x,v 1.9 1996/07/02 00:35:36 wpaul Exp $";
 %#endif /* not lint */
 #endif
 
@@ -81,6 +81,9 @@ const _YPMAXPEER = 64;
 /* Suggested default -- not necesarrily the one used. */
 const YPXFRBLOCK = 32767;
 
+/*
+ * Possible return codes from the remote server.
+ */
 enum xfrstat {
 	XFR_REQUEST_OK	= 1,	/* Transfer request granted */
 	XFR_DENIED	= 2,	/* Transfer request denied */
@@ -89,16 +92,71 @@ enum xfrstat {
 	XFR_BADDB	= 5,	/* File is not a hash database */
 	XFR_READ_OK	= 6,	/* Block read successfully */
 	XFR_READ_ERR	= 7,	/* Read error during transfer */
-	XFR_DONE	= 8	/* Transfer completed */
+	XFR_DONE	= 8,	/* Transfer completed */
+	XFR_DB_ENDIAN_MISMATCH	= 9,	/* Database byte order mismatch */
+	XFR_DB_TYPE_MISMATCH	= 10	/* Database type mismatch */
+};
+
+/*
+ * Database type specifications. The client can use this to ask
+ * the server for a particular type of database or just take whatever
+ * the server has to offer.
+ */
+enum xfr_db_type {
+	XFR_DB_ASCII		= 1,	/* Flat ASCII text */
+	XFR_DB_BSD_HASH		= 2,	/* Berkeley DB, hash method */
+	XFR_DB_BSD_BTREE	= 3,	/* Berkeley DB, btree method */
+	XFR_DB_BSD_RECNO	= 4,	/* Berkeley DB, recno method */
+	XFR_DB_BSD_MPOOL	= 5,	/* Berkeley DB, mpool method */
+	XFR_DB_BSD_NDBM		= 6,	/* Berkeley DB, hash, ndbm compat */
+	XFR_DB_GNU_GDBM		= 7,	/* GNU GDBM */
+	XFR_DB_DBM		= 8,	/* Old, deprecated dbm format */
+	XFR_DB_NDBM		= 9,	/* ndbm format (used by Sun's NISv2) */
+	XFR_DB_OPAQUE		= 10,	/* Mystery format -- just pass along */
+	XFR_DB_ANY		= 11,	/* I'll take any format you've got */
+	XFR_DB_UNKNOWN		= 12	/* Unknown format */
+};
+
+/*
+ * Machine byte order specification. This allows the client to check
+ * that it's copying a map database from a machine of similar byte sex.
+ * This is necessary for handling database libraries that are fatally
+ * byte order sensitive.
+ *
+ * The XFR_ENDIAN_ANY type is for use with the Berkeley DB database
+ * formats; Berkeley DB is smart enough to make up for byte order
+ * differences, so byte sex isn't important.
+ */
+enum xfr_byte_order {
+	XFR_ENDIAN_BIG		= 1,	/* We want big endian */
+	XFR_ENDIAN_LITTLE	= 2,	/* We want little endian */
+	XFR_ENDIAN_ANY		= 3	/* We'll take whatever you got */
 };
 
 typedef string xfrdomain<_YPMAXDOMAIN>;
 typedef string xfrmap<_YPMAXMAP>;
+typedef string xfrmap_filename<_YPMAXMAP>;	/* actual name of map file */
+typedef enum xfrstat xfrstat;
+typedef enum xfr_db_type xfr_db_type;
+typedef enum xfr_byte_order xfr_byte_order;
 
-/* Ask the remote ypxfrd for a map using this structure */
+/*
+ * Ask the remote ypxfrd for a map using this structure.
+ * Note: we supply both a map name and a map file name. These are not
+ * the same thing. In the case of ndbm, maps are stored in two files:
+ * map.bykey.pag and may.bykey.dir. We may also have to deal with
+ * file extensions (on the off chance that the remote server is supporting
+ * multiple DB formats). To handle this, we tell the remote server both
+ * what map we want and, in the case of ndbm, whether we want the .dir
+ * or the .pag part. This name should not be a fully qualified path:
+ * it's up to the remote server to decide which directories to look in.
+ */
 struct ypxfr_mapname {
 	xfrmap xfrmap;
 	xfrdomain xfrdomain;
+	xfrmap_filename xfrmap_filename;
+	xfr_db_type xfr_db_type;
+	xfr_byte_order xfr_byte_order;
 };
 
 /* Read response using this structure. */
@@ -106,7 +164,7 @@ union xfr switch (bool ok) {
 case TRUE:
 	opaque xfrblock_buf<>;
 case FALSE:
-	enum xfrstat xfrstat;
+	xfrstat xfrstat;
 };
 
 program YPXFRD_FREEBSD_PROG {