rpc_clnt_create(3rpc)

rpc_clnt_create: clnt_control, clnt_create, clnt_destroy, clnt_dg_create, clnt_pcreateerror, clnt_raw_create, clnt_spcreateerror, clnt_tli_create, clnt_tp_create, clnt_vc_create -- library routines for dealing with creation and manipulation of CLIENT handles

Synopsis

cc [options] file -lnsl

#include <rpc/rpc.h>

bool_t clnt_control(CLIENT *clnt, const u_int req, char *info);

CLIENT *clnt_create(const char *host, const u_long prognum,
	const u_long versnum, const char *nettype);

void clnt_destroy(CLIENT *clnt);

CLIENT *clnt_dg_create(const int fd, const struct netbut *svcaddr,
	const u_long prognum, const u_long versnum,
	const u_int sendsz, const u_int recvsz);

void clnt_pcreateerror(const char *s);

CLIENT *clnt_raw_create(const u_long prognum, const u_long versnum);

char *clnt_spcreateerror(const char *s);

CLIENT *clnt_tli_create(const int fd, const struct netconfig *netconf,
	const struct netbuf *svcaddr, const u_long prognum,
	const u_long versnum, const u_ini sendsz,
	const u_int recvsz);

CLIENT *clnt_tp_create(const char *host, const u_long prognum,
	const u_long versnum, const struct netconfig *netconf);

CLIENT *clnt_vc_create(const int fd, const struct netbuf * svcaddr,
	const u_long prognum, const u_long versnum,
	const u_int sendsz, const u_int recvsz);

Description

RPC library routines allow C language programs to make procedure calls on other machines across the network. First a CLIENT handle is created and then the client calls a procedure to send a data packet to the server. Upon receipt of the packet, the server calls a dispatch routine to perform the requested service, and then sends back a reply.

Routines

See rpc(3rpc) for the definition of the CLIENT data structure.

   bool_t
   clnt_control(CLIENT *clnt, const u_int req, char *info);

A function macro used to change or retrieve various information about a client object. req indicates the type of operation, and info is a pointer to the information. For both connectionless and connection-oriented transports, the supported values of req and their argument types and what they do are shown in the following table:

CLSET_TIMEOUT struct timeval Set total timeout

CLGET_TIMEOUT struct timeval Get total timeout

CLGET_FD int Get the associated file descriptor

CLGET_SVC_ADDR struct netbuf Get server's address

CLSET_FD_CLOSE int Explicitly close the associated file descriptor when the client handle is destroyed; see clnt_destroy, below

CLSET_FD_NCLOSE int Do not close the associated file descriptor when the client handle is destroyed; see clnt_destroy, below

Note that if you set the timeout using clnt_control, the timeout parameter passed to clnt_call will be ignored in all future calls.

The following operations are valid for connectionless transports only:

CLSET_RETRY_TIMEOUT struct timeval Set the retry timeout

CLGET_RETRY_TIMEOUT struct timeval Get the retry timeout

The retry timeout is the time that RPC waits for the server to reply before retransmitting the request.

clnt_control returns 1 on success and 0 on failure.

CLIENT *
clnt_create(const char *host, const u_long prognum,
	const u_long versnum, const char *nettype);

Generic client creation routine for program prognum and version versnum. host identifies the name of the remote host where the server is located. nettype indicates the class of transport protocol to use. The transports are tried in left to right order in NETPATH variable or in top to down order in the netconfig database.

clnt_create tries all the transports of the nettype class available from the NETPATH environment variable and the netconfig database, and chooses the first successful one. Default timeouts are set, but can be modified using clnt_control.

void
clnt_destroy(CLIENT *clnt);

A function macro that destroys the client's RPC handle. Destruction usually involves deallocation of private data structures, including clnt itself. Use of clnt is undefined after calling clnt_destroy. If the RPC library opened the associated file descriptor, or CLSET_FD_CLOSE was set using clnt_control, it will be closed.

CLIENT *
clnt_dg_create(const int fd, const struct netbuf *svcaddr,
	const u_long prognum, const u_long versnum,
	const u_int sendsz, const u_int recvsz);

This routine creates an RPC client for the remote program prognum and version versnum; the client uses a connectionless transport. The remote program is located at address svcaddr. The parameter fd is an open and bound file descriptor. This routine will resend the call message in intervals of 15 seconds until a response is received or until the call times out. The total time for the call to time out is specified by clnt_call (see clnt_call(3rpc)). This routine returns NULL if it fails. The retry time out and the total time out periods can be changed using clnt_control. The user may set the size of the send and receive buffers with the parameters sendsz and recvsz; values of 0 choose suitable defaults.

void
clnt_pcreateerror(const char *s);

Print a message to standard error indicating why a client RPC handle could not be created. The message is prepended with the string s and a colon, and appended with a newline.

CLIENT *
clnt_raw_create(const u_long prognum, const u_long versnum);

This routine creates a toy RPC client for the remote program prognum and version versnum. The transport used to pass messages to the service is a buffer within the process's address space, so the corresponding RPC server should live in the same address space; (see svc_raw_create(3rpc)). This allows simulation of RPC and acquisition of RPC overheads, such as round trip times, without any kernel interference. This routine returns NULL if it fails. clnt_raw_create should be called after svc_raw_create.

   char *
   clnt_spcreateerror(const char *s);

Like clnt_pcreateerror, except that it returns a string instead of printing to the standard error. A newline is not appended to the message in this case.

Note: clnt_spcreateerror returns a pointer to static data that is overwritten on each call.

   CLIENT *
   clnt_tli_create(const int fd, const struct netconfig *netconf,
   	const struct netbuf *svcaddr, const u_long prognum,
   	const u_long versnum, const u_int sendsz,
   	const u_int recvsz);

This routine creates an RPC client handle for the remote program prognum and version versnum. The remote program is located at address svcaddr. If svcaddr is NULL and it is connection-oriented, it is assumed that the file descriptor is connected. For connectionless transports, if svcaddr is NULL, RPC_UNKNOWNADDR error is set. fd is a file descriptor which may be open, bound and connected. If it is RPC_ANYFD, it opens a file descriptor on the transport specified by netconf. If netconf is NULL, a RPC_UNKNOWNPROTO error is set. If fd is unbound, then it will attempt to bind the descriptor. The user may specify the size of the buffers with the parameters sendsz and recvsz; values of 0 choose suitable defaults. Depending upon the type of the transport (connection-oriented or connectionless), clnt_tli_create calls appropriate client creation routines. This routine returns NULL if it fails. clnt_pcreateerror can be used to print the reason for failure. The remote rpcbind service (see rpcbind(1Mtcp)) will not be consulted for the address of the remote service.

   CLIENT *
   clnt_tp_create(const char *host, const u_long prognum,
   	const u_long versnum, const struct netconfig *netconf);

clnt_tp_create creates a client handle for the transport specified by netconf. Default options are set, which can be changed using clnt_control calls. The remote rpcbind service on the host host is consulted for the address of the remote service. This routine returns NULL if it fails. The clnt_pcreateerror routine can be used to print the reason for failure.

   CLIENT *
   clnt_vc_create(const int fd, const struct netbuf *svcaddr,
   	const u_long prognum, const u_long versnum,
   	const u_int sendsz, const u_int recvsz);

This routine creates an RPC client for the remote program prognum and version versnum; the client uses a connection-oriented transport. The remote program is located at address svcaddr. The parameter fd is an open and bound file descriptor. The user may specify the size of the send and receive buffers with the parameters sendsz and recvsz; values of 0 choose suitable defaults. This routine returns NULL if it fails.

The address svcaddr should not be NULL and should point to the actual address of the remote program. clnt_vc_create will not consult the remote rpcbind service for this information.

Files

/usr/lib/locale/locale/LC_MESSAGES/uxns1

References

rpcbind(1Mtcp), rpc(3rpc), rpc_clnt_auth(3rpc), rpc_clnt_calls(3rpc)

CLSET_TIMEOUT	struct timeval	Set total timeout
CLGET_TIMEOUT	struct timeval	Get total timeout
CLGET_FD	int	Get the associated file descriptor
CLGET_SVC_ADDR	struct netbuf	Get server's address
CLSET_FD_CLOSE	int	Explicitly close the associated file descriptor when the client handle is destroyed; see clnt_destroy, below
CLSET_FD_NCLOSE	int	Do not close the associated file descriptor when the client handle is destroyed; see clnt_destroy, below

CLSET_RETRY_TIMEOUT	struct timeval	Set the retry timeout
CLGET_RETRY_TIMEOUT	struct timeval	Get the retry timeout