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(5) 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(5)


August 1, 2001 RPC_CLNT_CALLS(3NSL)