libc/rpc/rpc_svc_calls.3

.\" @(#)rpc_svc_calls.3n 1.28 93/05/10 SMI; from SVr4
.\" Copyright 1989 AT&T
.\" @(#)rpc_svc_calls 1.5 89/07/25 SMI;
.\" Copyright (c) 1988 Sun Microsystems, Inc. - All Rights Reserved.
.\"	$NetBSD: rpc_svc_calls.3,v 1.13 2017/10/25 16:49:24 abhinav Exp $
.Dd May 3, 1993
.Dt RPC_SVC_CALLS 3
.Os
.Sh NAME
.Nm svc_dg_enablecache ,
.Nm svc_exit ,
.Nm svc_fdset ,
.Nm svc_freeargs ,
.Nm svc_getargs ,
.Nm svc_getreq_common ,
.Nm svc_getreq_poll ,
.Nm svc_getreqset ,
.Nm svc_getrpccaller ,
.Nm __svc_getcallercreds ,
.Nm svc_pollset ,
.Nm svc_run ,
.Nm svc_sendreply
.Nd library routines for RPC servers
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In rpc/rpc.h
.Ft int
.Fn svc_dg_enablecache "SVCXPRT *xprt" "const unsigned cache_size"
.Ft void
.Fn svc_exit "void"
.Ft bool_t
.Fn svc_freeargs "const SVCXPRT *xprt" "const xdrproc_t inproc" "caddr_t in"
.Ft bool_t
.Fn svc_getargs "const SVCXPRT *xprt" "const xdrproc_t inproc" "caddr_t in"
.Ft void
.Fn svc_getreq_common "const int fd"
.Ft void
.Fn svc_getreq_poll "struct pollfd *pfdp" "const int pollretval"
.Ft void
.Fn svc_getreqset "fd_set * rdfds"
.Ft "struct netbuf *"
.Fn svc_getrpccaller "const SVCXPRT *xprt"
.Ft "struct sockcred *"
.Fn __svc_getcallercreds "const SVCXPRT *xprt"
.Vt struct pollfd svc_pollset[FD_SETSIZE];
.Ft void
.Fn svc_run "void"
.Ft bool_t
.Fn svc_sendreply "const SVCXPRT *xprt" "const xdrproc_t outproc" "const caddr_t *out"
.Sh DESCRIPTION
These routines are part of the
RPC
library which allows C language programs to make procedure
calls on other machines across the network.
.Pp
These routines are associated with the server side of the
RPC mechanism.
Some of them are called by the server side dispatch function,
while others
(such as
.Fn svc_run )
are called when the server is initiated.
.\" .Pp
.\" In the current implementation, the service transport handle,
.\" .Dv SVCXPRT ,
.\" contains a single data area for decoding arguments and encoding results.
.\" Therefore, this structure cannot be freely shared between threads that call
.\" functions that do this.  Routines on this page that are affected by this
.\" restriction are marked as unsafe for MT applications.
.Sh ROUTINES
See
.Xr rpc 3
for the definition of the
.Dv SVCXPRT
data structure.
.Bl -tag -width __svc_getcallercreds()
.It Fn svc_dg_enablecache
This function allocates a duplicate request cache for the
service endpoint
.Fa xprt ,
large enough to hold
.Fa cache_size
entries.
Once enabled, there is no way to disable caching.
This routine returns 0 if space necessary for a cache of the given size
was successfully allocated, and 1 otherwise.
.It Fn svc_exit
This function when called by any of the RPC server procedure or
otherwise, causes
.Fn svc_run
to return.
.Pp
As currently implemented,
.Fn svc_exit
zeroes the
.Dv svc_fdset
global variable.
If RPC server activity is to be resumed,
services must be reregistered with the RPC library
either through one of the
.Fn rpc_svc_create
functions, or using
.Fn xprt_register .
.Fn svc_exit
has global scope and ends all RPC server activity.
.Ft "fd_set svc_fdset"
A global variable reflecting the
RPC server's read file descriptor bit mask; it is suitable as a parameter
to the
.Xr select 2
system call.
This is only of interest
if service implementors do not call
.Fn svc_run ,
but rather do their own asynchronous event processing.
This variable is read-only (do not pass its address to
.Xr select 2 ! ) ,
yet it may change after calls to
.Fn svc_getreqset
or any creation routines.
.It Fn svc_freeargs
A function macro that frees any data allocated by the
RPC/XDR system when it decoded the arguments to a service procedure
using
.Fn svc_getargs .
This routine returns
.Dv TRUE
if the results were successfully
freed, and
.Dv FALSE
otherwise.
.It Fn svc_getargs
A function macro that decodes the arguments of an
RPC request associated with the RPC
service transport handle
.Fa xprt .
The parameter
.Fa in
is the address where the arguments will be placed;
.Fa inproc
is the XDR
routine used to decode the arguments.
This routine returns
.Dv TRUE
if decoding succeeds, and
.Dv FALSE
otherwise.
.It Fn svc_getreq_common
This routine is called to handle a request on the given
file descriptor.
.It Fn svc_getreq_poll
This routine is only of interest if a service implementor
does not call
.Fn svc_run ,
but instead implements custom asynchronous event processing.
It is called when
.Xr poll 2
has determined that an RPC request has arrived on some RPC
file descriptors;
.Fn pollretval
is the return value from
.Xr poll 2
and
.Fa pfdp
is the array of
.Fa pollfd
structures on which the
.Xr poll 2
was done.
It is assumed to be an array large enough to
contain the maximal number of descriptors allowed.
.It Fn svc_getreqset
This routine is only of interest if a service implementor
does not call
.Fn svc_run ,
but instead implements custom asynchronous event processing.
It is called when
.Xr poll 2
has determined that an RPC
request has arrived on some RPC file descriptors;
.Fa rdfds
is the resultant read file descriptor bit mask.
The routine returns when all file descriptors
associated with the value of
.Fa rdfds
have been serviced.
.It Fn svc_getrpccaller
The approved way of getting the network address of the caller
of a procedure associated with the
RPC service transport handle
.Fa xprt .
.It Fn __svc_getcallercreds
.Em Warning: this macro is specific to
.Nx
.Em and thus not portable.
This macro returns a pointer to a sockcred structure, defined in
.In sys/socket.h ,
identifying the calling client.
This only works if the client is calling the server over an
.Dv AF_LOCAL
socket.
.It Fa struct pollfd svc_pollset[FD_SETSIZE];
.Va svc_pollset
is an array of
.Vt pollfd
structures derived from
.Va svc_fdset[] .
It is suitable as a parameter to the
.Xr  poll 2
system call.
The derivation of
.Va svc_pollset
from
.Va svc_fdset
is made in the current implementation in
.Fn svc_run .
Service implementors who do not call
.Fn svc_run
and who wish to use this array must perform this derivation themselves.
.It Fn svc_run
This routine never returns.
It waits for RPC
requests to arrive, and calls the appropriate service
procedure using
.Fn svc_getreq_poll
when one arrives.
This procedure is usually waiting for the
.Xr poll 2
system call to return.
.It Fn svc_sendreply
Called by an RPC service's dispatch routine to send the results of a
remote procedure call.
The parameter
.Fa xprt
is the request's associated transport handle;
.Fa outproc
is the XDR
routine which is used to encode the results; and
.Fa out
is the address of the results.
This routine returns
.Dv TRUE
if it succeeds,
.Dv FALSE
otherwise.
.El
.Sh SEE ALSO
.Xr poll 2 ,
.Xr rpc 3 ,
.Xr rpc_svc_create 3 ,
.Xr rpc_svc_err 3 ,
.Xr rpc_svc_reg 3