Testing Programs Using Low-Level Raw RPC

Two pseudo-RPC interface routines bypass all the network software. The routines shown in clnt_raw_create() and svc_raw_create() do not use any real transport.

The following code example is compiled and linked using the following makefile:

all: raw
CFLAGS += -g
raw: raw.o
cc -g -o raw raw.o -lnsl 

Example 4-19 Simple Program Using Raw RPC

/*
 * A simple program to increment a number by 1
 */
 
#include <stdio.h>
#include <rpc/rpc.h>

#include <rpc/raw.h>
#define prognum 0x40000001
#define versnum 1
#define INCR 1
 
struct timeval TIMEOUT = {0, 0};
static void server();
 
main (argc, argv)
    int argc;
    char **argv;
{
    CLIENT *cl;
    SVCXPRT *svc;
    int num = 0, ans;
    int flag;
 
    if (argc == 2)
        num = atoi(argv[1]);
        svc = svc_raw_create();
    if (svc == (SVCXPRT *) NULL) {
        fprintf(stderr, "Could not create server handle\n");
        exit(1);
    }
    flag = svc_reg( svc, prognum, versnum, server,
            (struct netconfig *) NULL );
    if (flag == 0) {
        fprintf(stderr, "Error: svc_reg failed.\n");
        exit(1);
    }
    cl = clnt_raw_create( prognum, versnum );
    if (cl == (CLIENT *) NULL) {
        clnt_pcreateerror("Error: clnt_raw_create");
        exit(1);
    }
    if (clnt_call(cl, INCR, xdr_int, (caddr_t) &num, xdr_int,

          (caddr_t) &ans, TIMEOUT)
      != RPC_SUCCESS) {
        clnt_perror(cl, "Error: client_call with raw");
        exit(1);
    }
    printf("Client: number returned %d\n", ans);
    exit(0);
}
 
static void
server(rqstp, transp)
    struct svc_req *rqstp;
    SVCXPRT *transp;
{
    int num;
 
    fprintf(stderr, "Entering server procedure.\n");
 
    switch(rqstp->rq_proc) {
        case NULLPROC:
            if (svc_sendreply( transp, xdr_void,
                (caddr_t) NULL) == FALSE) {
                fprintf(stderr, "error in null proc\n");
                exit(1);
            }
            return;
        case INCR:
            break;
        default:
            svcerr_noproc(transp);
            return;
    }
    if (!svc_getargs( transp, xdr_int, &num)) {
        svcerr_decode(transp);
        return;
    }
    fprintf(stderr, "Server procedure: about to increment.\n");
    num++;
    if (svc_sendreply(transp, xdr_int, &num) == FALSE) {
        fprintf(stderr, "error in sending answer\n");
        exit (1);
    }
    fprintf(stderr, "Leaving server procedure.\n");
}

Note the following points about the example:

• The server must be created before the client.

• svc_raw_create() has no parameters.

• The server is not registered with rpcbind. The last parameter to svc_reg() is (struct netconfig *) NULL.

• svc_run() is not called.

• All the RPC calls occur within the same thread of control.

• The server-dispatch routine is the same as for normal RPC servers.