RPC_CLNT_CALLS(3NSL) Networking Services Library Functions RPC_CLNT_CALLS(3NSL)
NAME
rpc_clnt_calls, clnt_call, clnt_send, clnt_freeres, clnt_geterr,
clnt_perrno, clnt_perror, clnt_sperrno, clnt_sperror, rpc_broadcast,
rpc_broadcast_exp, rpc_call - library routines for client side calls
SYNOPSIS
#include <rpc/rpc.h>
enum clnt_stat clnt_call(
CLIENT *clnt,
const rpcproc_t procnum,
const xdrproc_t inproc,
const caddr_t in,
const xdrproc_t outproc,
caddr_t out,
const struct timeval tout);
enum clnt_stat clnt_send (
CLIENT *clnt,
const u_long procnum,
const xdrproc_t proc,
const caddr_t in);
bool_t clnt_freeres(
CLIENT *clnt,
const xdrproc_t outproc,
caddr_t out);
void clnt_geterr(
const CLIENT *clnt,
struct rpc_err *errp);
void clnt_perrno(
const enum clnt_stat stat);
void clnt_perror(
const CLIENT *clnt,
const char *s);
char *clnt_sperrno(
const enum clnt_stat stat);
char *clnt_sperror(
const CLIENT *clnt,
const char *s);
enum clnt_stat rpc_broadcast(
const rpcprog_t prognum,
const rpcvers_t versnum,
const rpcproc_t procnum,
const xdrproc_tinproc,
const caddr_t in,
const xdrproc_t outproc,
caddr_t out,
const resultproc_t eachresult,
const char *nettype);
enum clnt_stat rpc_broadcast_exp(
const rpcprog_t prognum,
const rpcvers_t versnum,
const rpcproc_t procnum,
const xdrproc_txargs,
caddr_t argsp,
const xdrproc_txresults,
caddr_t resultsp,
const resultproc_t eachresult,
const int inittime,
const int waittime,
const char *nettype);
enum clnt_stat rpc_call(
const char *host,
const rpcprog_t prognum,
const rpcvers_t versnum,
const rpcproc_t procnum,
const xdrproc_t inproc,
const char *in,
const xdrproc_t outproc,
char *out,
const char *nettype);
DESCRIPTION
RPC library routines allow
C language programs to make procedure calls
on other machines across the network. First, the client calls a procedure
to send a request to the server. Upon receipt of the request, the server
calls a dispatch routine to perform the requested service and then sends
back a reply.
The
clnt_call(),
rpc_call(), and
rpc_broadcast() routines handle the
client side of the procedure call. The remaining routines deal with error
handling.
Some of the routines take a
CLIENT handle as one of the parameters. A
CLIENT handle can be created by an
RPC creation routine such as
clnt_create(). See
rpc_clnt_create(3NSL).
These routines are safe for use in multithreaded applications.
CLIENT handles can be shared between threads; however, in this implementation
requests by different threads are serialized. In other words, the first
request will receive its results before the second request is sent.
Routines
See
rpc(3NSL) for the definition of the
CLIENT data structure.
clnt_call() A function macro that calls the remote procedure
procnum associated with the client handle,
clnt,
which is obtained with an
RPC client creation
routine such as
clnt_create(). See
rpc_clnt_create(3NSL). The parameter
inproc is
the
XDR function used to encode the procedure's
parameters, and
outproc is the
XDR function used
to decode the procedure's results.
in is the
address of the procedure's argument(s), and
out is
the address of where to place the result(s).
tout is the time allowed for results to be returned,
which is overridden by a time-out set explicitly
through
clnt_control(). See
rpc_clnt_create(3NSL).
If the remote call succeeds, the status returned
is
RPC_SUCCESS. Otherwise, an appropriate status
is returned.
clnt_send() Use the
clnt_send() function to call a remote
asynchronous function.
The
clnt_send() function calls the remote function
procnum() associated with the client handle,
clnt,
which is obtained with an RPC client creation
routine such as
clnt_create(). See
rpc_clnt_create(3NSL). The parameter
proc is the
XDR function used to encode the procedure's
parameters. The parameter
in is the address of the
procedure's argument(s).
By default, the blocking I/O mode is used. See the
clnt_control(3NSL) man page for more information
on I/O modes.
The
clnt_send() function does not check if the
program version number supplied to
clnt_create() is registered with the
rpcbind service. Use
clnt_create_vers() instead of
clnt_create() to
check on incorrect version number registration.
clnt_create_vers() will return a valid handle to
the client only if a version within the range
supplied to
clnt_create_vers() is supported by the
server.
RPC_SUCCESS is returned when a request is
successfully delivered to the transport layer.
This does not mean that the request was received.
If an error is returned, use the
clnt_getterr() routine to find the failure status or the
clnt_perrno() routine to translate the failure
status into error messages.
clnt_freeres() A function macro that frees any data allocated by
the
RPC/XDR system when it decoded the results of
an
RPC call. The parameter
out is the address of
the results, and
outproc is the
XDR routine
describing the results. This routine returns
1 if
the results were successfully freed; otherwise it
returns
0.
clnt_geterr() A function macro that copies the error structure
out of the client handle to the structure at
address
errp.
clnt_perrno() Prints a message to standard error corresponding
to the condition indicated by
stat. A newline is
appended. It is normally used after a procedure
call fails for a routine for which a client handle
is not needed, for instance
rpc_call() clnt_perror() Prints a message to the standard error indicating
why an
RPC call failed;
clnt is the handle used to
do the call. The message is prepended with string
s and a colon. A newline is appended. This routine
is normally used after a remote procedure call
fails for a routine that requires a client handle,
for instance
clnt_call().
clnt_sperrno() Takes the same arguments as
clnt_perrno(), but
instead of sending a message to the standard error
indicating why an
RPC call failed, returns a
pointer to a string that contains the message.
clnt_sperrno() is normally used instead of
clnt_perrno() when the program does not have a
standard error, as a program running as a server
quite likely does not.
clnt_sperrno() is also used
if the programmer does not want the message to be
output with
printf(), or if a message format
different than that supported by
clnt_perrno() is
to be used. See
printf(3C). Unlike
clnt_sperror() and
clnt_spcreaterror(),
clnt_sperrno() does not
return a pointer to static data. Therefore, the
result is not overwritten on each call. See
rpc_clnt_create(3NSL).
clnt_sperror() Similar to
clnt_perror(), except that like
clnt_sperrno(), it returns a string instead of
printing to standard error. However,
clnt_sperror() does not append a newline at the
end of the message.
clnt_sperror() returns a pointer to a buffer that
is overwritten on each call. In multithreaded
applications, this buffer is implemented as
thread-specific data.
rpc_broadcast() Similar to
rpc_call(), except that the call
message is broadcast to all the connectionless
transports specified by
nettype. If
nettype is
NULL, it defaults to
netpath. Each time it
receives a response, this routine calls
eachresult(), whose form is:
bool_t eachresult(caddr_t out, const struct netbuf *addr,
const struct netconfig *netconf);
where
out is the same as
out passed to
rpc_broadcast(), except that the remote
procedure's output is decoded there.
addr points
to the address of the machine that sent the
results, and
netconf is the netconfig structure of
the transport on which the remote server
responded. If
eachresult() returns
0,
rpc_broadcast() waits for more replies; otherwise,
it returns with appropriate status.
The broadcast file descriptors are limited in size
to the maximum transfer size of that transport.
For Ethernet, this value is 1500 bytes.
rpc_broadcast() uses
AUTH_SYS credentials by
default. See
rpc_clnt_auth(3NSL).
rpc_broadcast_exp() Similar to
rpc_broadcast(), except that the
initial timeout,
inittime and the maximum timeout,
waittime, are specified in milliseconds.
inittime is the initial time that
rpc_broadcast_exp() waits before resending the
request. After the first resend, the
retransmission interval increases exponentially
until it exceeds
waittime.
rpc_call() Calls the remote procedure associated with
prognum,
versnum, and
procnum on the machine,
host. The parameter
inproc is used to encode the
procedure's parameters, and
outproc is used to
decode the procedure's results.
in is the address
of the procedure's argument(s), and
out is the
address of where to place the result(s).
nettype can be any of the values listed on
rpc(3NSL). This
routine returns
RPC_SUCCESS if it succeeds, or it
returns an appropriate status. Use the
clnt_perrno() routine to translate failure status
into error messages.
The
rpc_call() function uses the first available
transport belonging to the class
nettype on which
it can create a connection. You do not have
control of timeouts or authentication using this
routine.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Architecture | All |
+--------------------+-----------------+
|Interface Stability | Evolving |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+
SEE ALSO
printf(3C),
rpc(3NSL),
rpc_clnt_auth(3NSL),
rpc_clnt_create(3NSL),
attributes(7) August 1, 2001
RPC_CLNT_CALLS(3NSL)