path: root/lib/libc/rpc/rpc.3

.\"	$OpenBSD: rpc.3,v 1.10 1998/03/11 18:55:40 deraadt Exp $
.\" Mostly converted to mandoc by Theo de Raadt, Tue Feb 24 04:04:46 MST 1998
.\"
.Dd February 16, 1988
.Dt RPC 3
.Os
.Sh NAME
.Nm callrpc ,
.Nm clnt_broadcast ,
.Nm clnt_call ,
.Nm clnt_control ,
.Nm clnt_create ,
.Nm clnt_destroy ,
.Nm clnt_freeres ,
.Nm clnt_pcreateerror ,
.Nm clnt_perrno ,
.Nm clnt_perror ,
.Nm clnt_spcreateerror ,
.Nm clnt_sperrno ,
.Nm clnt_sperror ,
.Nm clntraw_create ,
.Nm clnttcp_create ,
.Nm clntudp_bufcreate ,
.Nm clntudp_create ,
.Nm clntudp_create ,
.Nm cnlt_geterr ,
.Nm get_myaddress ,
.Nm pmap_getmaps ,
.Nm pmap_getport ,
.Nm pmap_rmtcall ,
.Nm pmap_set ,
.Nm pmap_unset ,
.Nm registerrpc ,
.Nm rpc_createerr ,
.Nm svc_fdset ,
.Nm svc_freeargs ,
.Nm svc_getargs ,
.Nm svc_getcaller ,
.Nm svc_getreq ,
.Nm svc_getreqset ,
.Nm svc_register ,
.Nm svc_sendreply ,
.Nm svc_unregister ,
.Nm svcerr_auth ,
.Nm svcerr_decode ,
.Nm svcerr_noproc ,
.Nm svcerr_noprog ,
.Nm svcerr_progvers ,
.Nm svcerr_systemerr ,
.Nm svcerr_weakauth ,
.Nm svcfd_create ,
.Nm svctcp_create ,
.Nm svcudp_bufcreate ,
.Nm xdr_accepted_reply ,
.Nm xdr_authunix_parms ,
.Nm xdr_callhdr ,
.Nm xdr_callmsg ,
.Nm xdr_opaque_auth ,
.Nm xdr_pmap ,
.Nm xdr_pmaplist ,
.Nm xdr_rejected_reply ,
.Nm xdr_replymsg ,
.Nm xprt_register ,
.Nm xprt_unregister
.Nd library routines for remote procedure calls
.Sh SYNOPSIS
.Fd #include <rpc.h>
.Ft int
.Fn callrpc "char *host" "u_long prognum" "u_long versnum" "u_long procnum" "xdrproc_t inproc" "char *in" "xdrproc_t outproc" "char *out"
.Ft "enum clnt_stat"
.Fn clnt_broadcast "u_long prognum" "u_long versnum" "u_long procnum" "xdrproc_t inproc" "char *in" "xdrproc_t outproc" "char *out" "resultproc_t eachresult"
.Ft "enum clnt_stat"
.Fn clnt_call "CLIENT *clnt" "u_long procnum" "xdrproc_t inproc" "char *in" "xdrproc_t outproc" "char *out" "struct timeval tout"
.Ft int
.Fn clnt_destroy "CLIENT *clnt"
.Ft CLIENT *
.Fn clnt_create "char *host" "u_long prog" "u_long vers" "char *proto"
.Ft bool_t
.Fn clnt_control "CLIENT *cl" "char *info"
.Ft int
.Fn clnt_freeres "CLIENT *clnt" "xdrproc_t outproc" "char *out"
.Ft void
.Fn clnt_geterr "CLIENT *clnt" "struct rpc_err *errp"
.Ft void
.Fn clnt_pcreateerror "char *s"
.Ft void
.Fn clnt_perrno "enum clnt_stat stat"
.Ft int
.Fn clnt_perror "CLIENT *clnt" "char *s"
.Ft char *
.Fn clnt_spcreateerror "char *s"
.Ft char *
.Fn clnt_sperrno "enum clnt_stat stat"
.Ft char *
.Fn clnt_sperror "CLIENT *rpch" "char *s"
.Ft CLIENT *
.Fn clntraw_create "u_long prognum" "u_long versnum"
.Ft CLIENT *
.Fn clnttcp_create "struct sockaddr_in *addr" "u_long prognum" "u_long versnum" "int *sockp" "u_int sendsz" "u_int recvsz"
.Ft CLIENT *
.Fn clntudp_create "struct sockaddr_in *addr" "u_long prognum" "u_long versnum" "struct timeval wait" "int *sockp"
.Ft CLIENT *
.Fn clntudp_bufcreate "struct sockaddr_in *addr" "u_long prognum" "u_long versnum" "struct timeval wait" "int *sockp" "unsigned int sendsize" "unsigned int recosize"
.Ft int
.Fn get_myaddress "struct sockaddr_in *addr"
.Ft struct pmaplist *
.Fn pmap_getmaps "struct sockaddr_in *addr"
.Ft u_short
.Fn pmap_getport "struct sockaddr_in *addr" "u_long prognum" "u_long versnum" "u_long protocol"
.\" XXX the following works around an apparent nroff line length bug.
.Ft "enum clnt_stat"
.Fn pmap_rmtcall "struct sockaddr_in *" "u_long prog, vers, proc" "xdrproc_t inp" "char *in" "xdrproc_t outp" "char *out" "struct timeval tv" "u_long *portp"
.Ft int
.Fn pmap_set "u_long prognum" "u_long versnum" "u_long protocol" "u_short port"
.Ft int
.Fn pmap_unset "u_long prognum" "u_long versnum"
.Ft int
.Fn registerrpc "u_long prognum" "u_long versnum" "u_long procnum" "char *(*procname)() " "xdrproc_t inproc" "xdrproc_t outproc"
.Ft struct rpc_createerr
.Fa rpc_createerr ;
.Ft int
.Fn svc_destroy "SVCXPRT *xprt"
.Ft fd_set
.Fa svc_fdset ;
.Ft fd_set
.Fa *__svc_fdset ;
.Ft int
.Fa __svc_fdsetsize ;
.Ft int
.Fa svc_fds ;
.Ft int
.Fn svc_freeargs "SVCXPRT *xprt" "xdrproc_t inproc" "char *in"
.Ft int
.Fn svc_getargs "SVCXPRT *xprt" "xdrproc_t inproc" "char *in"
.Ft struct sockaddr_in *
.Fn svc_getcaller "SVCXPRT *xprt"
.Ft int
.Fn svc_getreqset "fd_set *rdfds"
.Ft int
.Fn svc_getreq "int rdfds"
.Ft int
.Fn svc_register "SVCXPRT *xprt" "u_long prognum" "u_long versnum" "void (*dispatch)()" "u_long protocol"
.Ft int
.Fn svc_run "void"
.Ft int
.Fn svc_sendreply "SVCXPRT *xprt" "xdrproc_t outproc" "char *out"
.Ft void
.Fn svc_unregister "u_long prognum" "u_long versnum"
.Ft void
.Fn svcerr_auth "SVCXPRT *xprt" "enum auth_stat why"
.Ft void
.Fn svcerr_decode "SVCXPRT *xprt"
.Ft void
.Fn svcerr_noproc "SVCXPRT *xprt"
.Ft void
.Fn svcerr_noprog "SVCXPRT *xprt"
.Ft void
.Fn svcerr_progvers "SVCXPRT *xprt"
.Ft void
.Fn svcerr_systemerr "SVCXPRT *xprt"
.Ft void
.Fn svcerr_weakauth "SVCXPRT *xprt"
.Ft SVCXPRT *
.Fn svcraw_create "void"
.Ft SVCXPRT *
.Fn svctcp_create "int sock" "u_int send_buf_size" "u_int recv_buf_size"
.Ft SVCXPRT *
.Fn svcfd_create "int fd" "u_int sendsize" "u_int recvsize"
.Ft SVCXPRT *
.Fn svcudp_bufcreate "int sock"
.Fn xdr_accepted_reply "XDR *xdrs" "struct accepted_reply *ar"
.Fn xdr_authunix_parms "XDR *xdrs" "struct authunix_parms *aupp"
.Ft void
.Fn xdr_callhdr "XDR *xdrs" "struct rpc_msg *chdr"
.Ft int
.Fn xdr_callmsg "XDR *xdrs" "struct rpc_msg *cmsg"
.Ft int
.Fn xdr_opaque_auth "XDR *xdrs" "struct opaque_auth *ap"
.Ft int
.Fn xdr_pmap "XDR *xdrs" "struct pmap *regs"
.Ft int
.Fn xdr_pmaplist "XDR *xdrs" "struct pmaplist **rp"
.Ft int
.Fn xdr_rejected_reply "XDR *xdrs" "struct rejected_reply *rr"
.Ft int
.Fn xdr_replymsg "XDR *xdrs" "struct rpc_msg *rmsg"
.Ft void
.Fn xprt_register "SVCXPRT *xprt"
.Ft void
.Fn xprt_unregister "SVCXPRT *xprt"
.Sh DESCRIPTION
These routines allow C programs to make procedure
calls on other machines across the network.
First, the client calls a procedure to send a
data packet to the server.
Upon receipt of the packet, the server calls a dispatch routine
to perform the requested service, and then sends back a
reply.
Finally, the procedure call returns to the client.
.Pp
.\"Routines that are used for Secure RPC (DES authentication) are described in
.\".Xr rpc_secure 3 .
.\"Secure RPC can be used only if DES encryption is available.
.Fn callrpc
calls the remote procedure associated with
.Fa prognum ,
.Fa versnum ,
and
.Fa procnum
on the machine,
.Fa host .
The parameter
.Fa in
is the address of the procedure's argument(s), and
.Fa out
is the address of where to place the result(s);
.Fa inproc
is used to encode the procedure's parameters, and
.Fa outproc
is used to decode the procedure's results.
This routine returns zero if it succeeds, or the value of
.Fa"enum clnt_stat"
cast to an integer if it fails.
The routine
.Fn clnt_perrno
is handy for translating failure statuses into messages.
.Pp
Warning: calling remote procedures with this routine
uses
.Tn UDP/IP
as a transport; see
.Fn clntudp_create
for restrictions.
You do not have control of timeouts or authentication using
this routine.
.Pp
.Fn clnt_broadcast
is like
.Fn callrpc ,
except the call message is broadcast to all locally
connected broadcast nets. Each time it receives a
response, this routine calls
.Fa eachresult ,
whose form is:
.Bd -literal -offset indent
.Ft int
.Fn eachresult "char *out" "struct sockaddr_in *addr"
.Ed
.Pp
where
.Fa out
is the same as
.Fa out
passed to
.Fn clnt_broadcast ,
except that the remote procedure's output is decoded there;
.Fa addr
points to the address of the machine that sent the results.
If
.Fa eachresult
returns zero,
.Fn clnt_broadcast
waits for more replies; otherwise it returns with appropriate
status.
.IP
Warning: broadcast sockets are limited in size to the
maximum transfer unit of the data link. For ethernet,
this value is 1500 bytes.
.Pp
.Fn clnt_call
is a macro that calls the remote procedure
.Fa procnum
associated with the client handle,
.Fa clnt ,
which is obtained with an
.Tn RPC
client creation routine such as
.Fn clnt_create .
The parameter
.Fa in
is the address of the procedure's argument(s), and
.Fa out
is the address of where to place the result(s);
.Fa inproc
is used to encode the procedure's parameters, and
.Fa outproc
is used to decode the procedure's results;
.Fa tout
is the time allowed for results to come back.
.Pp
.Fn clnt_destroy
is a macro that destroys the client's
.Tn RPC
handle. Destruction usually involves deallocation
of private data structures, including
.Fa clnt
itself.  Use of
.Fa clnt
is undefined after calling
.Fn clnt_destroy .
If the
.Tn RPC
library opened the associated socket, it will close it also.
Otherwise, the socket remains open.
.Pp
.Fn clnt_create
is a generic client creation routine.
.Fa host
identifies the name of the remote host where the server
is located.
.Fa proto
indicates which kind of transport protocol to use. The
currently supported values for this field are \(lqudp\(rq
and \(lqtcp\(rq.
Default timeouts are set, but can be modified using
.Fn clnt_control .
.IP
Warning: Using
.Tn UDP
has its shortcomings.  Since
.Tn UDP-based
.Tn RPC
messages can only hold up to 8 Kbytes of encoded data,
this transport cannot be used for procedures that take
large arguments or return huge results.
.Pp
.Fn clnt_control
is a macro used to change or retrieve various information
about a client object.
.Fa req
indicates the type of operation, and
.Fa info
is a pointer to the information. For both
.Tn UDP
and
.Tn TCP ,
the supported values of
.Fa req
and their argument types and what they do are:
.Pp
.Bd -literal -offset indent
.Tn CLSET_TIMEOUT	struct timeval	set total timeout
.Tn CLGET_TIMEOUT	struct timeval	get total timeout
.Ed
.Pp
Note: if you set the timeout using
.Fn clnt_control ,
the timeout parameter passed to
.Fn clnt_call
will be ignored in all future calls.
.Pp
.Bd -literal -offset indent
.Tn CLGET_SERVER_ADDR	struct sockaddr_in 	get server's address
.Ed
.Pp
The following operations are valid for
.Tn UDP
only:
.Pp
.Bd -literal -offset indent
.Tn CLSET_RETRY_TIMEOUT   struct timeval	set the retry timeout
.Tn CLGET_RETRY_TIMEOUT   struct timeval	get the retry timeout
.Ed
.Pp
The retry timeout is the time that
.Tn "UDP RPC"
waits for the server to reply before
retransmitting the request.
.Pp
.Fn clnt_freeres
is a macro that frees any data allocated by the
.Tn RPC/XDR
system when it decoded the results of an
.Tn RPC
call.  The
parameter
.Fa out
is the address of the results, and
.Fa outproc
is the
.Tn XDR
routine describing the results.
This routine returns one if the results were successfully
freed,
and zero otherwise.
.Pp
.Fn clnt_geterr
is a macro that copies the error structure out of the client
handle
to the structure at address
.Fa errp .
.Pp
.Fn clnt_pcreateerror
print a message to standard error indicating
why a client
.Tn RPC
handle could not be created.
The message is prepended with string
.Fa s
and a colon.
Used when a
.Fn clnt_create ,
.Fn clntraw_create ,
.Fn clnttcp_create ,
or
.Fn clntudp_create
call fails.
.Pp
.Fn clnt_perrno
prints a message to standard error corresponding
to the condition indicated by
.Fa stat .
Used after
.Fn callrpc .
.Pp
.Fn clnt_perror
prints a message to standard error indicating why an
.Tn RPC
call failed;
.Fa clnt
is the handle used to do the call.
The message is prepended with string
.Fa s
and a colon.
Used after
.Fn clnt_call .
.Pp
.Fn clnt_spcreateerror
is like
.Fn clnt_pcreateerror ,
except that it returns a string
instead of printing to the standard error.
.IP
Bugs: returns pointer to static data that is overwritten
on each call.
.Pp
.Fn clnt_sperrno
takes the same arguments as
.Fn clnt_perrno ,
but instead of sending a message to the standard error
indicating why an
.Tn RPC
call failed, return a pointer to a string which contains
the message.  The string ends with a
.Tn NEWLINE .
.IP
.Fn clnt_sperrno
is used instead of
.Fn clnt_perrno
if the program does not have a standard error (as a program
running as a server quite likely does not), or if the
programmer
does not want the message to be output with
.Fn printf ,
or if a message format different than that supported by
.Fn clnt_perrno
is to be used.
Note: unlike
.Fn clnt_sperror
and
.Fn clnt_spcreaterror ,
.Fn clnt_sperrno
returns pointer to static data, but the
result will not get overwritten on each call.
.Pp
.Fn clnt_sperror
is like
.Fn clnt_perror ,
except that (like
.Fn clnt_sperrno )
it returns a string instead of printing to standard error.
.IP
Bugs: returns pointer to static data that is overwritten
on each call.
.Pp
.Fn clntraw_create
is a routine which creates a toy
.Tn RPC
client for the remote program
.Fa prognum ,
version
.Fa versnum .
The transport used to pass messages to the service is
actually a buffer within the process's address space, so the
corresponding
.Tn RPC
server should live in the same address space; see
.Fn svcraw_create .
This allows simulation of
.Tn RPC
and acquisition of
.Tn RPC
overheads, such as round trip times, without any
kernel interference. This routine returns
.Tn NULL
if it fails.
.Pp
.Fn clnttcp_create
is a routine which creates an
.Tn RPC
client for the remote program
.Fa prognum ,
version
.Fa versnum ;
the client uses
.Tn TCP/IP
as a transport. The remote program is located at Internet
address
.Fa *addr .
If
.Fa addr\->sin_port
is zero, then it is set to the actual port that the remote
program is listening on (the remote
.Xr portmap 8
service is consulted for this information). The parameter
.Fa sockp
is a socket; if it is
.Fa RPC_ANYSOCK ,
then this routine opens a new one and sets
.Fa sockp .
Since
.Tn TCP-based
.Tn RPC
uses buffered
.Tn I/O ,
the user may specify the size of the send and receive buffers
with the parameters
.Fa sendsz
and
.Fa recvsz ;
values of zero choose suitable defaults.
This routine returns
.Tn NULL
if it fails.
.Pp
.Fn clntudp_create
is a routine which creates an
.Tn RPC
client for the remote program
.Fa prognum ,
on
.Fa versnum ;
the client uses use
.Tn UDP/IP
as a transport. The remote program is located at Internet
address
.Fa addr .
If
.Fa addr\->sin_port
is zero, then it is set to actual port that the remote
program is listening on (the remote
.Xr portmap 8
service is consulted for this information). The parameter
.Fa sockp
is a socket; if it is
.Fa RPC_ANYSOCK ,
then this routine opens a new one and sets
.Fa sockp .
The
.Tn UDP
transport resends the call message in intervals of
.Fa wait
time until a response is received or until the call times
out.
The total time for the call to time out is specified by
.Fn clnt_call .
.IP
This allows the user to specify the maximun packet size for sending and receiving 
.Tn UDP-based
.Tn RPC
messages.
.Pp
.Fn get_myaddress
stuffs the machine's
.Tn IP
address into
.Fa *addr ,
without consulting the library routines that deal with
.BR /etc/hosts .
The port number is always set to
.Fa htons(PMAPPORT) .
Returns zero on success, non-zero on failure.
.Pp
.Fn pmap_getmaps
is a function interface to the
.Xr portmap 8
service, which returns a list of the current
.Tn RPC
program-to-port mappings
on the host located at
.Tn IP
address
.Fa *addr .
This routine can return
.Tn NULL .
The command
.Pa ` "rpcinfo \-p" '
uses this routine.
.Pp
.Fn pmap_getport
is a user interface to the
.Xr portmap 8
service, which returns the port number
on which waits a service that supports program number
.Fa prognum ,
version
.Fa versnum ,
and speaks the transport protocol associated with
.Fa protocol .
The value of
.Fa protocol
is most likely
.B
.Tn IPPROTO_UDP
or 
.Fa IPPROTO_TCP .
A return value of zero means that the mapping does not exist
or that
the
.Tn RPC
system failured to contact the remote
.Xr portmap 8
service.  In the latter case, the global variable
.Fn rpc_createerr
contains the
.Tn RPC
status.
.Pp
.Fn pmap_rmtcall
is a user interface to the
.Xr portmap 8
service, which instructs
.Xr portmap 8
on the host at
.Tn IP
address
.Fa *addr
to make an
.Tn RPC
call on your behalf to a procedure on that host.
The parameter
.Fa *portp
will be modified to the program's port number if the
procedure
succeeds. The definitions of other parameters are discussed
in
.Fn callrpc
and
.Fn clnt_call .
This procedure should be used for a \(lqping\(rq and nothing
else.
See also
.Fn clnt_broadcast .
.Pp
.Fn pmap_set
is a user interface to the
.Xr portmap 8
service, which establishes a mapping between the triple
.Fa [ prognum , versnum , protocol]
and
.Fa port
on the machine's
.Xr portmap 8
service. The value of
.Fa protocol
is most likely
.B
.Tn IPPROTO_UDP
or 
.Fa IPPROTO_TCP .
This routine returns one if it succeeds, zero otherwise.
Automatically done by
.Fn svc_register .
.Pp
.Fn pmap_unset
is a user interface to the
.Xr portmap 8
service, which destroys all mapping between the triple
.Fa [ prognum , versnum , *]
and
.Fa ports
on the machine's
.Xr portmap 8
service. This routine returns one if it succeeds, zero
otherwise.
.Pp
.Fn registerrpc
will register a procedure
.Fa procname
with the
.Tn RPC
service package.  If a request arrives for program
.Fa prognum ,
version
.Fa versnum ,
and procedure
.Fa procnum ,
.Fa procname
is called with a pointer to its parameter(s);
.Fa progname
should return a pointer to its static result(s);
.Fa inproc
is used to decode the parameters while
.Fa outproc
is used to encode the results.
This routine returns zero if the registration succeeded, \-1
otherwise.
.IP
Warning: remote procedures registered in this form
are accessed using the
.Tn UDP/IP
transport; see
.Fn svcudp_create
for restrictions.
.Pp
.Fa rpc_createerr
is a global variable whose value is set by any
.Tn RPC
client creation routine
that does not succeed.  Use the routine
.Fn clnt_pcreateerror
to print the reason why.
.Pp
.Fn svc_destroy
is a macro that destroys the
.Tn RPC
service transport handle,
.Fa xprt .
Destruction usually involves deallocation
of private data structures, including
.Fa xprt
itself.  Use of
.Fa xprt
is undefined after calling this routine.
.Pp
.Fa __svc_fdset
and
.Fa __svc_fdsetsize
are global variables reflecting the
.Tn RPC
service side's
read file descriptor bit mask.
.Fa __svc_fdsetsize
is a count of the number of checkable bits in
.Fa __svc_fdset, and can expand to the full size that
.Xr select 2
supports, hence exceeding
.Fa FD_SETSIZE
if required.
These variables are 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, and it may change after calls
to svc_getreqset() or any creation routines.
Do not pass its address to
.Xr select 2 !
Instead, pass the address of a copy.
.Pp
.Fa svc_fdset
is similar to
.Fa __svc_fdset
but limited to
.Fa FD_SETSIZE
descriptors.
This is the preferred interface for portability though.
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, and it may change after calls
to svc_getreqset() or any creation routines.
Do not pass its address to
.Xr select 2 !
Instead, pass the address of a copy.
.br
As well, note that if the process has descriptor limits
which are extended beyond
.Fa FD_SETSIZE ,
this variable will only be usable for the first
.Fa FD_SETSIZE
descriptors.
.Pp
.Fa svc_fds
is similar to
.Fa svc_fedset ,
but limited to 32 descriptors. This
interface is obsoleted by
.Fa svc_fdset .
.Pp
.Fn svc_freeargs
is a macro that frees any data allocated by the
.Tn RPC/XDR
system when it decoded the arguments to a service procedure
using
.Fn svc_getargs .
This routine returns 1 if the results were successfully
freed,
and zero otherwise.
.Pp
.Fn svc_getargs
is a macro that decodes the arguments of an
.Tn RPC
request
associated with the
.Tn RPC
service transport handle,
.Fa xprt .
The parameter
.Fa in
is the address where the arguments will be placed;
.Fa inproc
is the
.Tn XDR
routine used to decode the arguments.
This routine returns one if decoding succeeds, and zero
otherwise.
.Pp
.Fn svc_getcaller
is the approved way of getting the network address of the caller
of a procedure associated with the
.Tn RPC
service transport handle,
.Fa xprt .
.Pp
.Fn svc_getreqset
is a routine which 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 the
.Xr select 2
system call has determined that an
.Tn RPC
request has arrived on some
.Tn RPC
.Fa socket(s) ;
.Fa rdfds
is the resultant read file descriptor bit mask.
The routine returns when all sockets associated with the
value of
.Fa rdfds
have been serviced.
.Pp
.Fn svc_getreq
is similar to
.Fa svc_getreqset ,
but limited to 32 descriptors. This interface is obsoleted by
.Fa svc_getreqset .
.Pp
.Fn svc_register
associates
.Fa prognum
and
.Fa versnum
with the service dispatch procedure,
.Fa dispatch .
If
.Fa protocol
is zero, the service is not registered with the
.Xr portmap 8
service.  If
.Fa protocol
is non-zero, then a mapping of the triple
.Fa [ prognum , versnum , protocol]
to
.Fa xprt\->xp_port
is established with the local
.Xr portmap 8
service (generally
.Fa protocol
is zero,
.B
.Tn IPPROTO_UDP
or 
.B
.Tn IPPROTO_TCP
).
The procedure
.Fa dispatch
has the following form:
.Ft int
.Fn dispatch "struct svc_req *request" "SVCXPRT *xprt"
The
.Fn svc_register
routine returns one if it succeeds, and zero otherwise.
.Pp
.Fn svc_run
never returns. It waits for
.Tn RPC
requests to arrive, and calls the appropriate service
procedure using
.Fn svc_getreq
when one arrives. This procedure is usually waiting for a
.Xr select 2
system call to return.
.Pp
.Fn svc_sendreply
is called by an
.Tn 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
.Tn XDR
routine which is used to encode the results; and
.Fa out
is the address of the results.
This routine returns one if it succeeds, zero otherwise.
.Pp
.Fn svc_unregister
removes all mapping of the double
.Fa [ prognum , versnum ]
to dispatch routines, and of the triple
.Fa [ prognum , versnum , *]
to port number.
.Pp
.Fn svcerr_auth
is called by a service dispatch routine that refuses to perform
a remote procedure call due to an authentication error.
.Pp
.Fn svcerr_decode
is called by a service dispatch routine that cannot successfully
decode its parameters. See also
.Fn svc_getargs .
.Pp
.Fn svcerr_noproc
is called by a service dispatch routine that does not implement
the procedure number that the caller requests.
.Pp
.Fn svcerr_noprog
is called when the desired program is not registered with the
.Tn RPC
package. Service implementors usually do not need this routine.
.Pp
.Fn svcerr_progvers
is called when the desired version of a program is not registered
with the
.Tn RPC
package. Service implementors usually do not need this routine.
.Pp
.Fn svcerr_systemerr
is called by a service dispatch routine when it detects a system
error
not covered by any particular protocol.
For example, if a service can no longer allocate storage,
it may call this routine.
.Pp
.Fn svcerr_weakauth
is called by a service dispatch routine that refuses to perform
a remote procedure call due to insufficient
authentication parameters.  The routine calls
.Fa "svcerr_auth(xprt, AUTH_TOOWEAK)" .
.Pp
.Fn svcraw_create
is a routine which creates a toy
.Tn RPC
service transport, to which it returns a pointer.  The
transport
is really a buffer within the process's address space,
so the corresponding
.Tn RPC
client should live in the same
address space;
see
.Fn clntraw_create .
This routine allows simulation of
.Tn RPC
and acquisition of
.Tn RPC
overheads (such as round trip times), without any kernel
interference.
This routine returns
.Tn NULL
if it fails.
.Pp
.Fn svctcp_create
is a routine which creates a
.Tn TCP/IP-based
.Tn RPC
service transport, to which it returns a pointer.
The transport is associated with the socket
.Fa sock ,
which may be
.Fa RPC_ANYSOCK ,
in which case a new socket is created.
If the socket is not bound to a local
.Tn TCP
port, then this routine binds it to an arbitrary port.  Upon
completion,
.Fa xprt\->xp_sock
is the transport's socket descriptor, and
.Fa xprt\->xp_port
is the transport's port number.
This routine returns
.Tn NULL
if it fails. Since
.Tn TCP-based
.Tn RPC
uses buffered
.Tn I/O ,
users may specify the size of buffers; values of zero
choose suitable defaults.
.Pp
.Fn svcfd_create
will create a service on top of any open descriptor. Typically,
this
descriptor is a connected socket for a stream protocol such
as
.Tn TCP.
.Fa sendsize
and
.Fa recvsize
indicate sizes for the send and receive buffers.  If they are
zero, a reasonable default is chosen.
.Pp
.Fn svcudp_bufcreate
is a routine which creates a
.Tn UDP/IP-based
.Tn RPC
service transport, to which it returns a pointer.
The transport is associated with the socket
.Fa sock ,
which may be
.Fa RPC_ANYSOCK ,
in which case a new socket is created.
If the socket is not bound to a local
.Tn UDP
port, then this routine binds it to an arbitrary port. Upon
completion,
.Fa xprt\->xp_sock
is the transport's socket descriptor, and
.Fa xprt\->xp_port
is the transport's port number.
This routine returns
.Tn NULL
if it fails.
.IP
This allows the user to specify the maximun packet size for sending and 
receiving
.Tn UDP-based
.Tn RPC messages.
.Pp
.Fn xdr_accepted_reply
is used for encoding
.Tn RPC
reply messages. This routine is useful for users who
wish to generate
RPC-style
messages without using the
.Tn RPC
package.
.Pp
.Fn xdr_authunix_parms
is used for describing
.Tn UNIX
credentials. This routine is useful for users
who wish to generate these credentials without using the
.Tn RPC
authentication package.
.Pp
.Fn xdr_callhdr
is used for describing
.Tn RPC
call header messages.
This routine is useful for users who wish to generate
.Tn RPC-style
messages without using the
.Tn RPC
package.
.Pp
.Fn xdr_callmsg
is used for describing
.Tn RPC
call messages.
This routine is useful for users who wish to generate
.Tn RPC-style
messages without using the
.Tn RPC
package.
.Pp
.Fn xdr_opaque_auth
is used for describing
.Tn RPC
authentication information messages.
This routine is useful for users who wish to generate
.Tn RPC-style
messages without using the
.Tn RPC
package.
.Pp
.Fn xdr_pmap
is used for describing parameters to various
.Xr portmap 8
procedures, externally.
This routine is useful for users who wish to generate
these parameters without using the pmap interface.
.Pp
.Fn xdr_pmaplist
is used for describing a list of port mappings, externally.
This routine is useful for users who wish to generate
these parameters without using the pmap interface.
.Pp
.Fn xdr_rejected_reply
is used for describing
.Tn RPC
reply messages.
This routine is useful for users who wish to generate
.Tn RPC-style
messages without using the
.Tn RPC
package.
.Pp
.Fn xdr_replymsg
is used for describing
.Tn RPC
reply messages.
This routine is useful for users who wish to generate
.Tn RPC
style messages without using the
.Tn RPC
package.
.Pp
.Fn xprt_register
is used to register transport handles.  After
.Tn RPC
service transport handles are created,
they should register themselves with the
.Tn RPC
service package.
This routine modifies the global variable
.Fa svc_fds .
Service implementors usually do not need this routine.
.Pp
.Fn xprt_unregister
is used to unregister a transport handle.  Before an
.Tn RPC
service transport handle is destroyed,
it should unregister itself with the
.Tn RPC
service package.
This routine modifies the global variable
.Fa svc_fds .
Service implementors usually do not need this routine.
.Sh SEE ALSO
.\"Xr rpc_secure 3 ,
.Xr getrpcent 3 ,
.Xr getrpcport 3 ,
.Xr portmap 8 ,
.Xr rpc 5 ,
.Xr rpcauth 3 ,
.Xr rpcgen 1 ,
.Xr select 2 ,
.Xr xdr 3 .
.br
The following manuals:
.RS
.ft I
Remote Procedure Calls: Protocol Specification
.br
Remote Procedure Call Programming Guide
.br
rpcgen Programming Guide
.br
.ft R
.RE
.Fa "RPC: Remote Procedure Call Protocol Specification" ,
.Tn RFC1050, Sun Microsystems, Inc.,
.Tn USC-ISI.