RPC_SVC_CALLS(3NSL) Networking Services Library Functions RPC_SVC_CALLS(3NSL)


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(5) 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.

SEE ALSO


rpcgen(1), poll(2), getpeerucred(3C), rpc(3NSL), rpc_control(3NSL),
rpc_svc_create(3NSL), rpc_svc_err(3NSL), rpc_svc_reg(3NSL), select(3C),
ucred_free(3C), attributes(5)


November 24, 2014 RPC_SVC_CALLS(3NSL)