Tribblix: manual page: rpc_clnt

RPC_CLNT_CALLS(3NSL) Networking Services Library Functions

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

NAME

SYNOPSIS

DESCRIPTION

Routines

ATTRIBUTES

SEE ALSO