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This article is supposed to give a positive answer for the question 23.10 from [1] Chapter "RPC" Originally only two files are taken from [1]: rdict.x and rdict_srp.c. All business logic is implemented into rdict_client.c file,generated by "rpcgen -a -M rdict.x" command. So,files rdict.c and rdict_cif.c (see [1] , Chapter "RPC") are just taken out.
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Source of rdict.x:
const MAXWORD=50;
const DICTSIZ=100;
struct example{
int exfield1;
char exfield2;
};
program RDICTPROG {
version RDICTVERS {
int INITW(void)=1;
int INSERTW(string)=2;
int DELETEW(string)=3;
int LOOKUPW(string)=4;
} =1;
} =0x30090949;
Source of rdict_srp.c :
#include<rpc/rpc.h>
#include<string.h>
#include "rdict.h"
char dict[DICTSIZ][MAXWORD+1];
static char snd[50];
static int lns;
int nwords=0;
int
initw()
{
nwords=0;
return 1;
}
int
insertw(char *word)
{
strcpy(dict[nwords],word);
nwords++;
return nwords;
}
int
deletew(char *word)
{
int i;
for(i=0;i<nwords;i++)
if(strcmp(word,dict[i])==0)
{
nwords--;
strcpy(dict[i],dict[nwords]);
return 1;
}
return 0;
}
int
lookupw(char *word)
{
int i;
for(i=0;i < nwords;i++)
if(strcmp(word,dict[i])==0)
return 1;
return 0;
}
rdictprog_1_freeresult(SVCXPRT *transp,xdrproc_t xdr_result,
caddr_t result)
{
xdr_free(xdr_result,result);
return(1);
}
Call rpcgen to generate stubs ,header file rdict.h and rdict_xdr:
$rpcgen -a -M rdict.x
Modified files on server's side follows bellow:
/*
* rdict_sif.c (compare with file rdict_sif.c in [1] chapter "RPC")
*/
#include<rpc/rpc.h>
#define RPC_SVC
#include "rdict.h"
int initw(void),insertw(char *),deletew(char *),lookupw(char *);
bool_t
insertw_1_svc(char **w,int *ptr_retcode,struct svc_req *rqstp)
{
*ptr_retcode=insertw(*(char **)w);
return(TRUE);
}
bool_t
initw_1_svc(void *w,int *ptr_retcode,struct svc_req *rqstp)
{
*ptr_retcode=initw();
return(TRUE);
}
bool_t
deletew_1_svc(char **w,int *ptr_retcode,struct svc_req *rqstp)
{
*ptr_retcode=deletew(*(char **)w);
return(TRUE);
}
bool_t
lookupw_1_svc(char **w,int *ptr_retcode,struct svc_req *rqstp)
{
*ptr_retcode=lookupw(*(char **)w);
return(TRUE);
}
Modified server's stub is file rdict_svc.c .
Multithreaded version
/* Modified rdict_svc.c
*
* Please do not edit this file.
* It was generated using rpcgen.
*/
#include "rdict.h"
#include <stdio.h>
#include <stdlib.h>
#include <rpc/pmap_clnt.h>
#include <string.h>
#include <memory.h>
#include <sys/socket.h>
#include <netinet/in.h>
#ifndef SIG_PF
#define SIG_PF void(*)(int)
#endif
pthread_t p_thread;
pthread_attr_t attr;
/* Procedure to be run by thread */
void *
serv_request(void *data)
{
struct thr_data
{
struct svc_req *rqstp;
SVCXPRT *transp;
} *ptr_data;
union {
char *insertw_1_arg;
char *deletew_1_arg;
char *lookupw_1_arg;
char *showupw_1_arg;
char *getlenw_1_arg;
} argument;
union {
int initw_1_res;
int insertw_1_res;
int deletew_1_res;
int lookupw_1_res;
char showupw_1_res;
int getlenw_1_res;
} result;
bool_t retval;
xdrproc_t _xdr_argument, _xdr_result;
bool_t (*local)(char *, void *, struct svc_req *);
ptr_data = (struct thr_data *)data;
struct svc_req *rqstp = ptr_data->rqstp;
register SVCXPRT *transp = ptr_data->transp;
switch (rqstp->rq_proc) {
case NULLPROC:
(void) svc_sendreply (transp, (xdrproc_t) xdr_void, (char *)NULL);
return;
case INITW:
_xdr_argument = (xdrproc_t) xdr_void;
_xdr_result = (xdrproc_t) xdr_int;
local = (bool_t (*) (char *, void *, struct svc_req *))initw_1_svc;
break;
case INSERTW:
_xdr_argument = (xdrproc_t) xdr_wrapstring;
_xdr_result = (xdrproc_t) xdr_int;
local = (bool_t (*) (char *, void *, struct svc_req *))insertw_1_svc;
break;
case DELETEW:
_xdr_argument = (xdrproc_t) xdr_wrapstring;
_xdr_result = (xdrproc_t) xdr_int;
local = (bool_t (*) (char *, void *, struct svc_req *))deletew_1_svc;
break;
case LOOKUPW:
_xdr_argument = (xdrproc_t) xdr_wrapstring;
_xdr_result = (xdrproc_t) xdr_int;
local = (bool_t (*) (char *, void *, struct svc_req *))lookupw_1_svc;
break;
default:
svcerr_noproc (transp);
return;
}
memset ((char *)&argument, 0, sizeof (argument));
if (!svc_getargs (transp, (xdrproc_t) _xdr_argument, (caddr_t) &argument)) {
svcerr_decode (transp);
return;
}
retval = (bool_t) (*local)((char *)&argument, (void *)&result, rqstp);
if (retval > 0 && !svc_sendreply(transp, (xdrproc_t) _xdr_result, (char *)&result)) {
svcerr_systemerr (transp);
}
if (!svc_freeargs (transp, (xdrproc_t) _xdr_argument, (caddr_t) &argument)) {
fprintf (stderr, "%s", "unable to free arguments");
exit (1);
}
if (!rdictprog_1_freeresult (transp, _xdr_result, (caddr_t) &result))
fprintf (stderr, "%s", "unable to free results");
return;
}
/*
New code for procedure rdictprog_1 , starting thread
in response for each clients request to invoke remote
procedure
*/
static void
rdictprog_1(struct svc_req *rqstp, register SVCXPRT *transp)
{
struct data_str
{
struct svc_req *rqstp;
SVCXPRT *transp;
} *data_ptr=(struct data_str*)malloc(sizeof(struct data_str));
data_ptr->rqstp = rqstp;
data_ptr->transp = transp;
pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_DETACHED);
pthread_create(&p_thread,&attr,serv_request,(void *)data_ptr);
}
int
main (int argc, char **argv)
{
register SVCXPRT *transp;
pmap_unset (RDICTPROG, RDICTVERS);
transp = svcudp_create(RPC_ANYSOCK);
if (transp == NULL) {
fprintf (stderr, "%s", "cannot create udp service.");
exit(1);
}
if (!svc_register(transp, RDICTPROG, RDICTVERS, rdictprog_1, IPPROTO_UDP)) {
fprintf (stderr, "%s", "unable to register (RDICTPROG, RDICTVERS, udp).");
exit(1);
}
transp = svctcp_create(RPC_ANYSOCK, 0, 0);
if (transp == NULL) {
fprintf (stderr, "%s", "cannot create tcp service.");
exit(1);
}
if (!svc_register(transp, RDICTPROG, RDICTVERS, rdictprog_1, IPPROTO_TCP)) {
fprintf (stderr, "%s", "unable to register (RDICTPROG, RDICTVERS, tcp).");
exit(1);
}
svc_run ();
fprintf (stderr, "%s", "svc_run returned");
exit (1);
/* NOTREACHED */
}
Compile server:
$ gcc -o ServerDT rdict_svc.c rdict_sif.c rdict_srp.c rdict_xdr.c -lpthread -lnsl
Modified code of rdict_client.c with implemented business logic.
Template has been already generated by "rpcgen -a -M rdict.x"
/* File rdict_client.c versus rdict.c&rdict_cif from [1] chapter "RPC"
*
* This is sample code generated by rpcgen.
* These are only templates and you can use them
* as a guideline for developing your own functions.
*/
#include "rdict.h"
#define MAXWORD 50
char buf[80];
void
rdictprog_1(char *host)
{
CLIENT *clnt;
enum clnt_stat retval_1;
int result_1;
char *initw_1_arg="0";
enum clnt_stat retval_2;
int result_2;
char * insertw_1_arg;
enum clnt_stat retval_3;
int result_3;
char * deletew_1_arg;
enum clnt_stat retval_4;
int result_4;
char * lookupw_1_arg;
int ch;
char cmd;
char word[MAXWORD+1];
int wrdlen;
#ifndef DEBUG
clnt = clnt_create (host, RDICTPROG, RDICTVERS, "udp");
if (clnt == NULL) {
clnt_pcreateerror (host);
exit (1);
}
#endif /* DEBUG */
while(1)
{
wrdlen=nextin(&cmd,word);
if(wrdlen < 0)
exit(0);
word[wrdlen]=' ';
switch(buf[0])
{
case 'I':
retval_1 = initw_1((void*)&initw_1_arg, &result_1, clnt);
if (retval_1 != RPC_SUCCESS) {
clnt_perror (clnt, "call failed");
}
if (result_1 == 1)
printf("Dictionary was initialized n");
else
printf("Dictionary failed to initialize n");
break;
case 'i':
insertw_1_arg=word;
retval_2 = insertw_1(&insertw_1_arg, &result_2, clnt);
if (retval_2 != RPC_SUCCESS) {
clnt_perror (clnt, "call failed");
}
if (result_2 >0 )
printf("Insert was donen");
else
printf("Insert failedn");
break;
case 'd':
deletew_1_arg=word;
retval_3 = deletew_1(&deletew_1_arg, &result_3, clnt);
if (retval_3 != RPC_SUCCESS) {
clnt_perror (clnt, "call failed");
}
if (result_3 == 1 )
printf("Delete was donen");
else
printf("Delete failedn");
break;
case 'l':
lookupw_1_arg=word;
retval_4 = lookupw_1(&lookupw_1_arg, &result_4, clnt);
if (retval_4 != RPC_SUCCESS) {
clnt_perror (clnt, "call failed");
}
if (result_4 == 1)
printf("Word '%s' was foundn",word);
else
printf("Word '%s' was not foundn",word);
break;
case 'q':
printf("Programm quits n");
exit(0);
default:
printf("Command invalidn");
break;
}
}
#ifndef DEBUG
clnt_destroy (clnt);
#endif /* DEBUG */
}
int
nextin(char *cmd,char *word)
{
int i,ch;
printf("n");
printf("***** Make a choice ******n");
printf("1. I(initialize dictionary)n");
printf("2. i(inserting word) n");
printf("3. l(looking for word)n");
printf("4. d(deleting word)n");
printf("5. q(quit)n");
printf("***************************n");
printf("Command prompt =>t");
ch=getc(stdin);
while(isspace(ch))
ch=getc(stdin);
if(ch==EOF)
return -1;
*cmd=(char)ch;
sprintf(buf,"%s",cmd);
if(buf[0] == 'q' || buf[0] == 'I')
return 0;
printf("*****************n");
printf("Analysing Commandn");
printf("*****************n");
if(buf[0]=='i' || buf[0]=='l'|| buf[0]=='d')
{
printf("Input word =>t");
}
else
{
return 0;
}
ch=getc(stdin);
while(isspace(ch))
ch=getc(stdin);
if(ch==EOF)
return -1;
if(ch=='n')
return 0;
i=0;
while(!isspace(ch))
{
if(++i>MAXWORD)
{
printf("Error word to long.n");
exit(1);
}
*word++=ch;
ch=getc(stdin);
}
return i;
}
int
main (int argc, char *argv[])
{
char *host;
if (argc < 2) {
printf ("usage: %s server_hostn", argv[0]);
exit (1);
}
host = argv[1];
rdictprog_1 (host);
exit (0);
}
Compile client:
$ gcc -o CientDT rdict_client.c rdict_clnt.c rdict_xdr.c -lnsl
Now we are ready for testing
References.
1.Douglas E. Comer,David L. Stevens Internet Working with TCP/IP ,vol 3
Client-Server Programming and application Linux/Posix Socket Version,
Prentice Hall,Inc. 2001
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