RPC (3)

SYNOPSIS AND 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.

Routines that are used for Secure RPC (DES authentication) are described in rpc_secure (3N). Secure RPC can be used only if DES encryption is available.

B

#include <rpc/rpc.h>

R t .ne 8

B

void
auth_destroy(auth)
\s-1AUTH\s0 *auth;

R
A macro that destroys the authentication information associated with auth . Destruction usually involves deallocation of private data structures. The use of auth is undefined after calling auth_destroy(\|) . t .ne 6

B

\s-1AUTH\s0 *
authnone_create(\|)

R
Create and returns an authentication handle that passes nonusable authentication information with each remote procedure call. This is the default authentication used by t .ne 10

B

\s-1AUTH\s0 *
authunix_create(host, uid, gid, len, aup_gids)
char *host;
int uid, gid, len, *aup.gids;

R
Create and return an authentication handle that contains authentication information. The parameter host is the name of the machine on which the information was created; uid is the user's user gid is the user's current group len and aup_gids refer to a counted array of groups to which the user belongs. It is easy to impersonate a user. t .ne 5

B

\s-1AUTH\s0 *
authunix_create_default(\|)

R
Calls authunix_create(\|) with the appropriate parameters. t .ne 13

B

callrpc(host, prognum, versnum, procnum, inproc, in, outproc, out)
char *host;
u_long prognum, versnum, procnum;
char *in, *out;
xdrproc_t inproc, outproc;

R
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. This routine returns zero if it succeeds, or the value of enum clnt_stat cast to an integer if it fails. The routine clnt_perrno(\|) is handy for translating failure statuses into messages.

Warning: calling remote procedures with this routine uses as a transport; see clntudp_create(\|) for restrictions. You do not have control of timeouts or authentication using this routine. t .ne 16

B

enum clnt_stat
clnt_broadcast(prognum, versnum, procnum, inproc, in, outproc, out, eachresult)
u_long prognum, versnum, procnum;
char *in, *out;
xdrproc_t inproc, outproc;
resultproc_t eachresult;

R
Like callrpc(\|) , except the call message is broadcast to all locally connected broadcast nets. Each time it receives a response, this routine calls eachresult(\|) , whose form is:

B

eachresult(out, addr)
char *out;
struct sockaddr_in *addr;
R

where out is the same as out passed to clnt_broadcast(\|) , except that the remote procedure's output is decoded there; addr points to the address of the machine that sent the results. If eachresult(\|) returns zero, clnt_broadcast(\|) waits for more replies; otherwise it returns with appropriate status.

Warning: broadcast sockets are limited in size to the maximum transfer unit of the data link. For ethernet, this value is 1500 bytes. t .ne 13

B

enum clnt_stat
clnt_call(clnt, procnum, inproc, in, outproc, out, tout)
\s-1CLIENT\s0 *clnt;
u_long
procnum;
xdrproc_t inproc, outproc;
char *in, *out;
struct timeval tout;

R
A macro that calls the remote procedure procnum associated with the client handle, clnt , which is obtained with an client creation routine such as clnt_create(\|) . 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 come back. t .ne 7

B

clnt_destroy(clnt)
\s-1CLIENT\s0 *clnt;

R
A macro that destroys the client's handle. Destruction usually involves deallocation of private data structures, including clnt itself. Use of clnt is undefined after calling clnt_destroy(\|) . If the library opened the associated socket, it will close it also. Otherwise, the socket remains open. t .ne 10

B

\s-1CLIENT\s0 *
clnt_create(host, prog, vers, proto)
char *host;
u_long prog, vers;
char *proto;

R
Generic client creation routine. host identifies the name of the remote host where the server is located. 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 clnt_control(\|) .

Warning: Using has its shortcomings. Since 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. t .ne 10

B

bool_t
clnt_control(cl, req, info)
\s-1CLIENT\s0 *cl;
char *info;

R
A macro used to change or retrieve various information about a client object. req indicates the type of operation, and info is a pointer to the information. For both and the supported values of req and their argument types and what they do are:

+2.0i +2.0i +2.0i

Note: if you set the timeout using clnt_control(\|) , the timeout parameter passed to clnt_call(\|) will be ignored in all future calls.

The following operations are valid for only:

+2.0i ; +2.0i ; +2.0i

The retry timeout is the time that waits for the server to reply before retransmitting the request. t .ne 10

B

clnt_freeres(clnt, outproc, out)
\s-1CLIENT\s0 *clnt;
xdrproc_t outproc;
char *out;

R
A macro that frees any data allocated by the system when it decoded the results of an call. The parameter out is the address of the results, and outproc is the routine describing the results. This routine returns one if the results were successfully freed, and zero otherwise. t .ne 6

B

void
clnt_geterr(clnt, errp)
\s-1CLIENT\s0 *clnt;
struct rpc_err *errp;

R
A macro that copies the error structure out of the client handle to the structure at address errp . t .ne 8

B

void
clnt_pcreateerror(s)
char *s;

R
Print a message to standard error indicating why a client handle could not be created. The message is prepended with string s and a colon. Used when a clnt_create(\|) , clntraw_create(\|) , clnttcp_create(\|) , or clntudp_create(\|) call fails. t .ne 8

B

void
clnt_perrno(stat)
enum clnt_stat stat;

R
Print a message to standard error corresponding to the condition indicated by stat . Used after callrpc(\|) . t .ne 8

B

clnt_perror(clnt, s)
\s-1CLIENT\s0 *clnt;
char *s;

R
Print a message to standard error indicating why an call failed; clnt is the handle used to do the call. The message is prepended with string s and a colon. Used after clnt_call(\|) . t .ne 9

B

char *
clnt_spcreateerror
char *s;

R
Like clnt_pcreateerror(\|) , except that it returns a string instead of printing to the standard error.

Bugs: returns pointer to static data that is overwritten on each call. t .ne 9

B

char *
clnt_sperrno(stat)
enum clnt_stat stat;

R
Take the same arguments as clnt_perrno(\|) , but instead of sending a message to the standard error indicating why an call failed, return a pointer to a string which contains the message. The string ends with a

clnt_sperrno(\|) is used instead of 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 printf , or if a message format different than that supported by clnt_perrno(\|) is to be used. Note: unlike clnt_sperror(\|) and clnt_spcreaterror(\|) , clnt_sperrno(\|) returns pointer to static data, but the result will not get overwritten on each call. t .ne 7

B

char *
clnt_sperror(rpch, s)
\s-1CLIENT\s0 *rpch;
char *s;

R
Like clnt_perror(\|) , except that (like clnt_sperrno(\|) ) it returns a string instead of printing to standard error.

Bugs: returns pointer to static data that is overwritten on each call. t .ne 10

B

\s-1CLIENT\s0 *
clntraw_create(prognum, versnum)
u_long prognum, versnum;

R
This routine creates a toy client for the remote program prognum , version versnum . The transport used to pass messages to the service is actually a buffer within the process's address space, so the corresponding server should live in the same address space; see svcraw_create(\|) . This allows simulation of and acquisition of overheads, such as round trip times, without any kernel interference. This routine returns if it fails. t .ne 15

B

\s-1CLIENT\s0 *
clnttcp_create(addr, prognum, versnum, sockp, sendsz, recvsz)
struct sockaddr_in *addr;
u_long prognum, versnum;
int *sockp;
u_int sendsz, recvsz;

R
This routine creates an client for the remote program prognum , version versnum ; the client uses as a transport. The remote program is located at Internet address *addr . If