NAME
rpc —
library routines for remote
procedure calls
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <rpc/rpc.h>
#include <netconfig.h>
DESCRIPTION
These routines allow C language programs to make procedure calls on other
machines across a network. First, the client sends a request to the server. On
receipt of the request, the server calls a dispatch routine to perform the
requested service, and then sends back a reply.
All RPC routines require the header
<rpc/rpc.h>. Routines that take a
netconfig structure also require that
<netconfig.h> be included.
Nettype
Some of the high-level RPC interface routines take a
nettype string as one of the parameters (for example,
clnt_create(),
svc_create(),
rpc_reg(),
rpc_call(). This string defines
a class of transports which can be used for a particular application.
nettype can be one of the following:
-
-
- netpath
- Choose from the transports which have been indicated by
their token names in the
NETPATH
environment
variable. If NETPATH
is unset or
NULL
, it defaults to
visible. netpath is the
default nettype.
-
-
- visible
- Choose the transports which have the visible flag (v) set
in the /etc/netconfig file.
-
-
- circuit_v
- This is same as visible except that
it chooses only the connection oriented transports (semantics
tpi_cots or tpi_cots_ord) from
the entries in the /etc/netconfig file.
-
-
- datagram_v
- This is same as visible except that
it chooses only the connectionless datagram transports (semantics
tpi_clts) from the entries in the
/etc/netconfig file.
-
-
- circuit_n
- This is same as netpath except that
it chooses only the connection oriented datagram transports (semantics
tpi_cots or
tpi_cots_ord).
-
-
- datagram_n
- This is same as netpath except that
it chooses only the connectionless datagram transports (semantics
tpi_clts).
-
-
- udp
- This refers to Internet UDP, both version 4 and 6.
-
-
- tcp
- This refers to Internet TCP, both version 4 and 6.
If
nettype is
NULL
, it defaults to
netpath. The transports are tried in left to right order
in the
NETPATH
variable or in top to down order in the
/etc/netconfig file.
Derived Types
The derived types used in the RPC interfaces are defined as follows:
typedef uint32_t rpcprog_t;
typedef uint32_t rpcvers_t;
typedef uint32_t rpcproc_t;
typedef uint32_t rpcprot_t;
typedef uint32_t rpcport_t;
typedef int32_t rpc_inline_t;
Data Structures
Some of the data structures used by the RPC package are shown below.
The AUTH Structure
/*
* Authentication info. Opaque to client.
*/
struct opaque_auth {
enum_t oa_flavor; /* flavor of auth */
caddr_t oa_base; /* address of more auth stuff */
u_int oa_length; /* not to exceed MAX_AUTH_BYTES */
};
/*
* Auth handle, interface to client side authenticators.
*/
typedef struct {
struct opaque_auth ah_cred;
struct opaque_auth ah_verf;
struct auth_ops {
void (*ah_nextverf)();
int (*ah_marshal)(); /* nextverf & serialize */
int (*ah_validate)(); /* validate verifier */
int (*ah_refresh)(); /* refresh credentials */
void (*ah_destroy)(); /* destroy this structure */
} *ah_ops;
caddr_t ah_private;
} AUTH;
The CLIENT Structure
/*
* Client rpc handle.
* Created by individual implementations.
* Client is responsible for initializing auth.
*/
typedef struct {
AUTH *cl_auth; /* authenticator */
struct clnt_ops {
enum clnt_stat (*cl_call)(); /* call remote procedure */
void (*cl_abort)(); /* abort a call */
void (*cl_geterr)(); /* get specific error code */
bool_t (*cl_freeres)(); /* frees results */
void (*cl_destroy)(); /* destroy this structure */
bool_t (*cl_control)(); /* the ioctl() of rpc */
} *cl_ops;
caddr_t cl_private; /* private stuff */
char *cl_netid; /* network identifier */
char *cl_tp; /* device name */
} CLIENT;
The SVCXPRT structure
enum xprt_stat {
XPRT_DIED,
XPRT_MOREREQS,
XPRT_IDLE
};
/*
* Server side transport handle
*/
typedef struct {
int xp_fd; /* file descriptor for the server handle */
u_short xp_port; /* obsolete */
const struct xp_ops {
bool_t (*xp_recv)(); /* receive incoming requests */
enum xprt_stat (*xp_stat)(); /* get transport status */
bool_t (*xp_getargs)(); /* get arguments */
bool_t (*xp_reply)(); /* send reply */
bool_t (*xp_freeargs)(); /* free mem allocated for args */
void (*xp_destroy)(); /* destroy this struct */
} *xp_ops;
int xp_addrlen; /* length of remote addr. Obsolete */
struct sockaddr_in xp_raddr; /* Obsolete */
const struct xp_ops2 {
bool_t (*xp_control)(); /* catch-all function */
} *xp_ops2;
char *xp_tp; /* transport provider device name */
char *xp_netid; /* network identifier */
struct netbuf xp_ltaddr; /* local transport address */
struct netbuf xp_rtaddr; /* remote transport address */
struct opaque_auth xp_verf; /* raw response verifier */
caddr_t xp_p1; /* private: for use by svc ops */
caddr_t xp_p2; /* private: for use by svc ops */
caddr_t xp_p3; /* private: for use by svc lib */
int xp_type /* transport type */
} SVCXPRT;
The svc_req structure
struct svc_req {
rpcprog_t rq_prog; /* service program number */
rpcvers_t rq_vers; /* service protocol version */
rpcproc_t rq_proc; /* the desired procedure */
struct opaque_auth rq_cred; /* raw creds from the wire */
caddr_t rq_clntcred; /* read only cooked cred */
SVCXPRT *rq_xprt; /* associated transport */
};
The XDR structure
/*
* XDR operations.
* XDR_ENCODE causes the type to be encoded into the stream.
* XDR_DECODE causes the type to be extracted from the stream.
* XDR_FREE can be used to release the space allocated by an XDR_DECODE
* request.
*/
enum xdr_op {
XDR_ENCODE=0,
XDR_DECODE=1,
XDR_FREE=2
};
/*
* This is the number of bytes per unit of external data.
*/
#define BYTES_PER_XDR_UNIT (4)
#define RNDUP(x) ((((x) + BYTES_PER_XDR_UNIT - 1) /
BYTES_PER_XDR_UNIT) \ * BYTES_PER_XDR_UNIT)
/*
* A xdrproc_t exists for each data type which is to be encoded or
* decoded. The second argument to the xdrproc_t is a pointer to
* an opaque pointer. The opaque pointer generally points to a
* structure of the data type to be decoded. If this points to 0,
* then the type routines should allocate dynamic storage of the
* appropriate size and return it.
*/
typedef bool_t (*xdrproc_t)(XDR *, const void *);
/*
* The XDR handle.
* Contains operation which is being applied to the stream,
* an operations vector for the particular implementation
*/
typedef struct {
enum xdr_op x_op; /* operation; fast additional param */
struct xdr_ops {
bool_t (*x_getlong)(); /* get a long from underlying stream */
bool_t (*x_putlong)(); /* put a long to underlying stream */
bool_t (*x_getbytes)(); /* get bytes from underlying stream */
bool_t (*x_putbytes)(); /* put bytes to underlying stream */
u_int (*x_getpostn)(); /* returns bytes off from beginning */
bool_t (*x_setpostn)(); /* lets you reposition the stream */
long * (*x_inline)(); /* buf quick ptr to buffered data */
void (*x_destroy)(); /* free privates of this xdr_stream */
} *x_ops;
caddr_t x_public; /* users' data */
caddr_t x_private; /* pointer to private data */
caddr_t x_base; /* private used for position info */
int x_handy; /* extra private word */
} XDR;
/*
* The netbuf structure. This structure is defined in <xti.h> on SysV
* systems, but NetBSD does not use XTI.
*
* Usually, buf will point to a struct sockaddr, and len and maxlen
* will contain the length and maximum length of that socket address,
* respectively.
*/
struct netbuf {
unsigned int maxlen;
unsigned int len;
void *buf;
};
/*
* The format of the address and options arguments of the XTI t_bind call.
* Only provided for compatibility, it should not be used other than
* as an argument to svc_tli_create().
*/
struct t_bind {
struct netbuf addr;
unsigned int qlen;
};
Index to Routines
The following table lists RPC routines and the manual reference pages on which
they are described:
FILES
/etc/netconfig
SEE ALSO
getnetconfig(3),
getnetpath(3),
rpc_clnt_auth(3),
rpc_clnt_calls(3),
rpc_clnt_create(3),
rpc_svc_calls(3),
rpc_svc_create(3),
rpc_svc_err(3),
rpc_svc_reg(3),
rpc_xdr(3),
rpcbind(3),
xdr(3),
netconfig(5)