This chapter describes the routines that specify external data representation. They allow C programmers to describe arbitrary data structures in a system-independent fashion. These routines transmit data for remote procedure calls.

Table 8-1 indicates the type of task that each routine performs.

Table 8-1 XDR Data Conversion Routines

Routine	Encodes and Decodes...
xdr_accepted_reply	Accepted RPC messages
xdr_array	Variable-length arrays
xdr_authunix_parms	UNIX-style authentication information
xdr_bool	Boolean values
xdr_bytes	Single bytes
xdr_callhdr	Static part of RPC request message headers
xdr_callmsg	RPC request messages
xdr_char	Single characters
xdr_double	Double-precision floating-point numbers
xdr_enum	Enumerations
xdr_float	Single-precision floating-point numbers
xdr_hyper	Quad words (hyperintegers)
xdr_int	4-byte integers
xdr_long	Longwords
xdr_opaque	Fixed-length opaque data structures
xdr_opaque_auth	Opaque opaque_auth structures containing authentication information
xdr_pmap	Portmapper parameters
xdr_pmap_vms	Portmapper parameters (including OpenVMS process IDs)
xdr_pmaplist	Portmapper lists
xdr_pmaplist_vms	Portmapper lists (including OpenVMS process IDs)
xdr_pointer	Data structure pointers
xdr_reference	Data structure pointers
xdr_rejected_reply	Rejected RPC reply messages
xdr_replymsg	RPC reply messages
xdr_short	2-byte integers
xdr_string	Null-terminated strings
xdr_u_char	Unsigned characters
xdr_u_hyper	Unsigned quadwords (hyperintegers)
xdr_u_int	Unsigned 4-byte integers
xdr_u_long	Unsigned long integers
xdr_u_short	Unsigned 2-byte integers
xdr_union	Unions
xdr_vector	Fixed-length arrays
xdr_void	(A dummy routine)
xdr_wrapstring	Null-terminated strings

This chapter also describes the XDR routines that manage XDR streams. They allow C programmers to handle XDR streams in a system-independent fashion.

Table 8-2 indicates the type of task that each routine performs.

Table 8-2 XDR Stream Handling Routines

Routine	Task
xdr_free	Deallocates an XDR data structure.
xdrmem_create	Creates an XDR stream handle describing a memory buffer.
xdrrec_create	Creates an XDR stream handle describing a record-oriented TCP-based connection.
xdrrec_endofrecord	Generates an end-of-record indication for an XDR record.
xdrrec_eof	Positions the data pointer to the end of the current XDR record and indicates whether any more records follow the current record.
xdrrec_skiprecord	Positions the data pointer at the end of the current XDR record.
xdrstdio_create	Creates an XDR stream handle describing a stdio stream.
xdr_accepted_reply	Accepts RPC messages.

Serializes and deserializes a message-accepted indication in an RPC reply message.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_accepted_reply(XDR *xdrs, struct accepted_reply *arp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

arp

A pointer to a buffer to which the message-accepted indication is written.

Description

Used for encoding reply messages. This routine encodes the status of the RPC call and, in the case of success, the call results as well. This routine is useful for users who want to generate messages without using the ONC RPC package. It returns the message-accepted variant of a reply message union in the arp argument.

The xdr_replymsg routine calls this routine.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure to encode the message.

Serializes and deserializes the elements of a variable-length array.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_array(XDR *xdrs, char **arrp, u_int *sizep, u_int maxsize, u_int elsize, xdrproc_t elproc);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

arrp

A pointer to the pointer to the array.

sizep

A pointer to the number of elements in the array. This element count cannot exceed the maxsize parameter.

maxsize

The maximum size of the sizep parameter. This value is the maximum number of elements that the array can hold.

elsize

The size, in bytes, of each of the array's elements.

elproc

The XDR routine to call that handles each element of the array.

Description

A filter primitive that translates between variable-length arrays and their corresponding external representations.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes credentials in an authentication parameter structure.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_authunix_parms (XDR *xdrs, struct authunix_parms *authp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

authp

A pointer to an authunix_parms structure.

Description

Used for externally describing standard UNIX credentials. On a TCP/IP Services host, this routine encodes the host name, the user ID, and the group ID. It sets the group ID list to NULL . This routine is useful for users who want to generate these credentials without using the ONC RPC authentication package.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes boolean data.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_bool (XDR *xdrs, bool_t *bp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

bp

A pointer to the boolean data.

Description

A filter primitive that translates between booleans (integers) and their external representations. When encoding data, this filter produces values of either 1 or 0.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes a counted byte array.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_bytes (XDR *xdrs, char **bpp, u_int *sizep, u_int maxsize);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

bpp

A pointer to a pointer to the byte array.

sizep

A pointer to the length of the byte array.

maxsize

The maximum size of the length of the byte array.

Description

A filter primitive that translates between a variable-length byte array and its external representation. The length of the array is located at sizep ; the array cannot be longer than maxsize . If *bpp is NULL , xdr_bytes allocates maxsize bytes.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes the static part of a call message header.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_callhdr(XDR *xdrs, struct rpc_msg *chdrp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

chdrp

A pointer to the call header data.

Description

Describes call header messages. This routine is useful for users who want to generate messages without using the ONC RPC package. The xdr_callhdr routine encodes the following fields: transaction ID, direction, RPC version, server program number, and server version.

Return Values

TRUE	Indicate success.
FALSE	Indicates failure.

Serializes and deserializes an ONC RPC call message.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_callmsg(XDR *xdrs, struct rpc_msg *cmsgp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

cmsgp

A pointer to an rpc_msg structure that describes the RPC call message.

Description

This routine is useful for users who want to generate messages without using the ONC RPC package. The xdr_callmsg routine encodes the following fields: transaction ID, direction, RPC version, server program number, server version number, server procedure number, and client authentication.

The pmap_rmtcall and svc_sendreply routines call xdr_callmsg .

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes character data.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_char(XDR *xdrs, char *cp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

cp

A pointer to a character.

Description

A filter primitive that translates between internal representations of characters and their XDR representations.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes VAX and IEEE double-precision floating-point numbers.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_double(XDR *xdrs, double *dp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

dp

A pointer to the double-precision floating-point number.

Description

A filter primitive that translates between double-precision numbers and their external representations.

This routine is implemented by four XDR routines:

xdr_double_D	Converts VAX D-format floating-point numbers.
xdr_double_G	Converts VAX G-format floating-point numbers.
xdr_double_T	Converts IEEE T-format floating-point numbers.
xdr_double_X	Converts IEEE X-format floating-point numbers.

You can reference these routines explicitly or you can use compiler settings to control which routine is used when you reference the xdr_double routine.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes enumerations.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_enum(XDR *xdrs, enum_t *ep);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

ep

A pointer to the enumeration data.

Description

A filter primitive that translates between enumerations (actually integers) and their external representations.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Serializes and deserializes VAX and IEEE single-precision floating-point numbers.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_float(XDR *xdrs, float *fp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

fp

A pointer to a single-precision floating-point number.

Description

A filter primitive that translates between single-precision floating-point numbers and their external representations.

This routine is implemented by two XDR routines:

xdr_float_F	Converts VAX F-format floating-point numbers.
xdr_float_S	Converts IEEE T-format floating-point numbers.

You can reference these routines explicitly or you can use compiler settings to control which routine is used when you reference the xdr_float routine.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.

Deallocates the memory associated with the indicated data structure.

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_free(xdrproc_t proc, char *objp);

Arguments

proc

The XDR routine for the data structure being freed.

objp

A pointer to the data structure to be freed.

Description

Releases memory allocated for the data structure to which objp points. The pointer passed to this routine is not freed, but what it points to is freed (recursively). Use this routine to free decoded data that is no longer needed. Never use this routine for encoded data.

Return Values

TRUE	Indicate success.
FALSE	Indicates failure.

Serializes and deserializes VAX quadwords (known in XDR as hyperintegers).

Format

#include <tcpip$rpcxdr.h>

bool_t xdr_hyper(XDR *xdrs, quad *hp);

Arguments

xdrs

A pointer to an XDR stream handle created by one of the XDR stream-handle creation routines.

hp

A pointer to the hyperinteger data.

Description

A filter primitive that translates between hyperintegers and their external representations.

Return Values

TRUE	Indicates success.
FALSE	Indicates failure.