Tribblix: manual page: rpc_svc

RPC_SVC_CALLS(3NSL) Networking Services Library Functions

NAME

rpc_svc_calls, svc_dg_enablecache, svc_done, svc_exit, svc_fdset,
svc_freeargs, svc_getargs, svc_getreq_common, svc_getreq_poll,
svc_getreqset, svc_getrpccaller, svc_max_pollfd, svc_pollfd, svc_run,
svc_sendreply, svc_getcallerucred, svc_fd_negotiate_ucred - library
routines for RPC servers

SYNOPSIS

cc [ flag... ] file... -lnsl [ library...]
#include <rpc/rpc.h>

int svc_dg_enablecache(SVCXPRT *xprt, const uint_t cache_size);

int svc_done(SVCXPRT *xprt);

void svc_exit(void);

void svc_fd_negotiate_ucred(int fd);

bool_t svc_freeargs(const SVCXPRT *xprt, const txdrproc_t inproc,
caddr_t in);

bool_t svc_getargs(const SVCXPRT *xprt, const xdrproc_t inproc,
caddr_t in);

int svc_getcallerucred(const SVCXPRT *xprt, ucred_t **ucred);

void svc_getreq_common(const int fd);

void svc_getreqset(fd_set *rdfds);

void svc_getreq_poll(struct pollfd *pfdp, const int pollretval);

struct netbuf *svc_getrpccaller(const SVCXPRT *xprt);

void svc_run(void);

bool_t svc_sendreply(const SVCXPRT *xprt, const xdrproc_t outproc,
caddr_t out);

int svc_max_pollfd;
fd_set svc_fdset;
pollfd_t *svc_pollfd;

DESCRIPTION

These routines are part of the RPC library which allows C language
programs to make procedure calls on other machines across the
network.

These routines are associated with the server side of the RPC
mechanism. Some of them are called by the server side dispatch
function. Others, such as svc_run(), are called when the server is
initiated.

Because the service transport handle SVCXPRT contains a single data
area for decoding arguments and encoding results, the structure
cannot freely be shared between threads that call functions to decode
arguments and encode results. When a server is operating in the
Automatic or User MT modes, however, a copy of this structure is
passed to the service dispatch procedure in order to enable
concurrent request processing. Under these circumstances, some
routines which would otherwise be Unsafe, become Safe. These are
marked as such. Also marked are routines that are Unsafe for
multithreaded applications, and are not to be used by such
applications. See rpc(3NSL) for the definition of the SVCXPRT data
structure.

The svc_dg_enablecache() function allocates a duplicate request cache
for the service endpoint xprt, large enough to hold cache_size
entries. Once enabled, there is no way to disable caching. The
function returns 1 if space necessary for a cache of the given size
was successfully allocated, and 0 otherwise. This function is Safe in
multithreaded applications.

The svc_done() function frees resources allocated to service a client
request directed to the service endpoint xprt. This call pertains
only to servers executing in the User MT mode. In the User MT mode,
service procedures must invoke this call before returning, either
after a client request has been serviced, or after an error or
abnormal condition that prevents a reply from being sent. After
svc_done() is invoked, the service endpoint xprt should not be
referenced by the service procedure. Server multithreading modes and
parameters can be set using the rpc_control() call. This function is
Safe in multithreaded applications. It will have no effect if invoked
in modes other than the User MT mode.

The svc_exit() function when called by any of the RPC server
procedures or otherwise, destroys all services registered by the
server and causes svc_run() to return. If RPC server activity is to
be resumed, services must be reregistered with the RPC library
through one of the rpc_svc_reg(3NSL) functions. The svc_exit()
function has global scope and ends all RPC server activity.

The svc_freeargs() function macro frees any data allocated by the
RPC/XDR system when it decoded the arguments to a service procedure
using svc_getargs(). This routine returns TRUE if the results were
successfully freed, and FALSE otherwise. This function macro is Safe
in multithreaded applications utilizing the Automatic or User MT
modes.

The svc_getargs() function macro decodes the arguments of an RPC
request associated with the RPC service transport handle xprt. The
parameter in is the address where the arguments will be placed;
inproc is the XDR routine used to decode the arguments. This routine
returns TRUE if decoding succeeds, and FALSE otherwise. This
function macro is Safe in multithreaded applications utilizing the
Automatic or User MT modes.

The svc_getreq_common() function is called to handle a request on a
file descriptor.

The svc_getreq_poll() function is only of interest if a service
implementor does not call svc_run(), but instead implements custom
asynchronous event processing. It is called when poll(2) has
determined that an RPC request has arrived on some RPC file
descriptors; pollretval is the return value from poll(2) and pfdp is
the array of pollfd structures on which the poll(2) was done. It is
assumed to be an array large enough to contain the maximal number of
descriptors allowed. The svc_getreq_poll() function macro is Unsafe
in multithreaded applications.

The svc_getreqset() function is only of interest if a service
implementor does not call svc_run(), but instead implements custom
asynchronous event processing. It is called when select(3C) has
determined that an RPC request has arrived on some RPC file
descriptors; rdfds is the resultant read file descriptor bit mask.
The routine returns when all file descriptors associated with the
value of rdfds have been serviced. This function macro is Unsafe in
multithreaded applications.

The svc_getrpccaller() function macro is the approved way of getting
the network address of the caller of a procedure associated with the
RPC service transport handle xprt. The returned pointer to struct
netbuf shouldn't be deallocated by the svc_getrpccaller() caller.
This function macro is Safe in multithreaded applications.

In single-threaded mode, the svc_run() function waits for RPC
requests to arrive. When an RPC request arrives, the svc_run()
function calls the appropriate service procedure. This procedure is
usually waiting for the poll(2) library call to return.

Applications that execute in the Automatic or the User MT mode should
invoke the svc_run() function exactly once. In the Automatic MT mode,
the svc_run() function creates threads to service client requests. In
the User MT mode, the function provides a framework for service
developers to create and manage their own threads for servicing
client requests.

The svc_fdset global variable reflects the RPC server's read file
descriptor bit mask. This is only of interest if service implementors
do not call svc_run(), but rather do their own asynchronous event
processing. This variable is read-only may change after calls to
svc_getreqset() or after any creation routine. Do not pass its
address to select(3C). Instead, pass the address of a copy.
Multithreaded applications executing in either the Automatic MT mode
or the User MT mode should never read this variable. They should use
auxiliary threads to do asynchronous event processing. The svc_fdset
variable is limited to 1024 file descriptors and is considered
obsolete. Use of svc_pollfd is recommended instead.

The svc_pollfd global variable points to an array of pollfd_t
structures that reflect the RPC server's read file descriptor array.
This is only of interest if service implementors do not call
svc_run() but rather do their own asynchronous event processing. This
variable is read-only, and it may change after calls to
svc_getreg_poll() or any creation routines. Do no pass its address to
poll(2). Instead, pass the address of a copy. By default, svc_pollfd
is limited to 1024 entries. Use rpc_control(3NSL) to remove this
limitation. Multithreaded applications executing in either the
Automatic MT mode or the User MT mode should never be read this
variable. They should use auxiliary threads to do asynchronous event
processing.

The svc_max_pollfd global variable contains the maximum length of the
svc_pollfd array. This variable is read-only, and it may change after
calls to svc_getreg_poll() or any creation routines.

The svc_sendreply() function is called by an RPC service dispatch
routine to send the results of a remote procedure call. The xprt
parameter is the transport handle of the request. The outproc
parameter is the XDR routine used to encode the results. The out
parameter is the address of the results. This routine returns TRUE if
it succeeds, FALSE otherwise. The svc_sendreply() function macro is
Safe in multithreaded applications that use the Automatic or the User
MT mode.

The svc_fd_negotiate_ucred() function is called by an RPC server to
inform the underlying transport that the function wishes to receive
ucreds for local calls, including those over IP transports.

The svc_getcallerucred() function attempts to retrieve the ucred_t
associated with the caller. The function returns 0 when successful
and -1 when not.

When successful, the svc_getcallerucred() function stores the pointer
to a freshly allocated ucred_t in the memory location pointed to by
the ucred argument if that memory location contains the null pointer.
If the memory location is non-null, the function reuses the existing
ucred_t. When ucred is no longer needed, a credential allocated by
svc_getcallerucred() should be freed with ucred_free(3C).

ATTRIBUTES

See attributes(7) for descriptions of attribute types and values.

+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT-Level | See below. |
+---------------+-----------------+

The svc_fd_negotiate_ucred(), svc_dg_enablecache(),
svc_getrpccaller(), and svc_getcallerucred() functions are Safe in
multithreaded applications. The svc_freeargs(), svc_getargs(), and
svc_sendreply() functions are Safe in multithreaded applications that
use the Automatic or the User MT mode. The svc_getreq_common(),
svc_getreqset(), and svc_getreq_poll() functions are Unsafe in
multithreaded applications and should be called only from the main
thread.

NAME

SYNOPSIS

DESCRIPTION

ATTRIBUTES

SEE ALSO