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 pro-
cedure 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.
If you use one of the RPC functions, you must link the libnsl library
at compilation (cc -lnsl).
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 associ-
ated with the client handle, clnt, which is obtained with an RPC
client creation routine such as clntcreate [see
rpcclntcreate(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 parame-
ters, 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);
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rpc_clnt_calls(3N) rpc_clnt_calls(3N)
A function macro that copies the error structure out of the
client handle to the structure at address errp.
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 mes-
sage. 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
rpcclntcreate(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.
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rpc_clnt_calls(3N) rpc_clnt_calls(3N)
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);
Like rpccall, except the call message is broadcast to the con-
nectionless network specified by nettype. If nettype is NULL, it
defaults to netpath. Each time it receives a response, this rou-
tine 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 rou-
tine. There is also no way to destroy the client handle.
SEE ALSO
rpc(3N), rpcclntauth(3N), rpcclntcreate(3N), printf(3S).
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