rpc_clnt_calls(3N) rpc_clnt_calls(3N)
NAME
rpcclntcalls: clntcall, clntfreeres, clntgeterr, clntperrno,
clntperror, clntsperrno, clntsperror, rpcbroadcast, rpccall -
library routines for client side calls
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 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.
The clntcall, rpccall and rpcbroadcast routines handle the client
side of the procedure call. The remaining routines deal with error
handling in the case of errors.
Routines
See rpc(3N) for the definition of the CLIENT data structure.
#include <rpc/rpc.h>
enum clntstat
clntcall(CLIENT *clnt, const ulong procnum, const xdrproct inproc,
caddrt in, const xdrproct outproc, caddrt out,
const struct timeval tout);
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 clntcreate [see
rpc_clnt_create(3N)]. The parameter in is the address of the
procedure's argument(s), and out is the address of where to
place the result(s); inproc is used to encode the procedure's
parameters, and outproc is used to decode the procedure's
results; tout is the time allowed for results to be returned.
If the remote call succeeds, the status is returned in
RPCSUCCESS, otherwise an appropriate status is returned.
int clntfreeres(CLIENT *clnt, const xdrproct outproc, caddrt out);
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, and 0 otherwise.
void
clntgeterr(const CLIENT *clnt, struct rpcerr *errp);
A function macro that copies the error structure out of the
client handle to the structure at address errp.
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rpc_clnt_calls(3N) rpc_clnt_calls(3N)
void
clntperrno(const enum clntstat stat);
Print a message to standard error corresponding to the
condition indicated by stat. A newline is appended at the end
of the message. Normally used after a procedure call fails,
for instance rpccall.
void
clntperror(const CLIENT *clnt, const char *s);
Print a message to 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 at
the end of the message. Normally used after a procedure call
fails, for instance clntcall.
char *
clntsperrno(const enum clntstat stat);
Take the same arguments as clntperrno, but instead of sending
a message to the standard error indicating why an RPC call
failed, return a pointer to a string which contains the
message.
clntsperrno is normally used instead of clntperrno when 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 printf [see printf(3S)], or
if a message format different than that supported by
clntperrno is to be used. Note: unlike clntsperror and
clntspcreaterror [see rpc_clnt_create(3N)], clntsperrno does
not return pointer to static data so the result will not get
overwritten on each call.
char *
clntsperror(const CLIENT *clnt, const char *s);
Like clntperror, except that (like clntsperrno) it returns a
string instead of printing to standard error. However,
clntsperror does not append a newline at the end of the
message.
Warning: returns pointer to static data that is overwritten on
each call.
enum clntstat
rpcbroadcast(const ulong prognum, const ulong versnum,
const ulong procnum, const xdrproct inproc, caddrt in,
const xdrproct outproc, caddrt out, const resultproct eachresult,
const char *nettype);
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rpc_clnt_calls(3N) rpc_clnt_calls(3N)
Like rpccall, except the call message is broadcast to the
connectionless network specified by nettype. If nettype is
NULL, it defaults to netpath. Each time it receives a
response, this routine calls eachresult, whose form is:
boolt
eachresult(const caddrt out, const struct netbuf *addr,
struct netconfig *netconf);
where out is the same as out passed to rpcbroadcast, 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,
rpcbroadcast waits for more replies; otherwise it returns with
appropriate status.
Warning: broadcast file descriptors are limited in size to the
maximum transfer size of that transport. For Ethernet, this
value is 1500 bytes.
enum clntstat
rpccall(const char *host, const ulong prognum,
const ulong versnum, const ulong procnum,
const xdrproct inproc, const xdrproct outproc,
const char *in, char *out, const char *nettype);
Call the remote procedure associated with prognum, versnum, and
procnum on the machine, host. The parameter in is the address
of the procedure's argument(s), and out is the address of where
to place the result(s); inproc is used to encode the
procedure's parameters, and outproc is used to decode the
procedure's results. nettype can be any of the values listed
on rpc(3N). If nettype is NULL, it defaults to netpath. This
routine returns 0 if it succeeds, or the value of enum
clntstat cast to an integer if it fails. Use the clntperrno
routine to translate failure statuses into messages.
Warning: rpccall 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. There is also no way to destroy the client handle.
SEE ALSO
printf(3S), rpc(3N), rpcclntauth(3N), rpcclntcreate(3N).
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