rpc_clnt_create(3N) rpc_clnt_create(3N)
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
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 [Toc] [Back]
See rpc(3N) for the definition of the CLIENT data structure.
#include <rpc/rpc.h>
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:
CLSET_TIMEOUT struct timevalset total timeout
CLGET_TIMEOUT struct timevalget total timeout
Note: if you set the timeout using clnt_control, the timeout
parameter passed to clnt_call will be ignored in all future calls.
CLGET_FD int get the associated file descriptor
CLGET_SVC_ADDR struct netbufget servers address
CLSET_FD_CLOSE intclose the file descriptor when
destroying the client handle
[see clnt_destroy]
CLSET_FD_NCLOSE intdo not close the file
descriptor when destroying
the client handle
The following operations are valid for connectionless transports
only:
CLSET_RETRY_TIMEOUT struct timevalset the retry timeout
CLGET_RETRY_TIMEOUT struct timevalget 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.
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rpc_clnt_create(3N) rpc_clnt_create(3N)
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 in rpc_clnt_calls(3N)].
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);
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rpc_clnt_create(3N) rpc_clnt_create(3N)
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 in rpc_clnt_calls(3N)]. 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: 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, u const_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. The clnt_pcreaterror routine can be used to print the
reason for failure. The remote rpcbind service [see rpcbind(1M)]
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_pcreaterror routine can be used
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rpc_clnt_create(3N) rpc_clnt_create(3N)
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.
rpcbind(1M), rpc(3N), rpc_clnt_auth(3N), rpc_clnt_calls(3N)
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