Remote Procedure Call Part 2

Transcription

1 Remote Procedure Call Part 2 York University COSC4213

2 The XDR File In our example, the only declared type is a structure with one integer filed and one character filed. rdict_xdr.c contains the code needed to convert a structure of type example from the native representation to the external data representation. If one of the remote procedures did use the an example structure, rpcgen would generate code in both client and server to call xdr_example to convert the representation.

3 Client code (rdict_clnt.c) /* * Please do not edit this file. * It was generated using rpcgen */ #include "rdict.h" #ifndef _KERNEL #include <stdio.h> #include <stdlib.h> /* getenv, exit */ #endif /*!_KERNEL */ /* Default timeout can be changed using clnt_control() */ static struct timeval TIMEOUT = 25, 0 ; int * initw_1(argp, clnt) void *argp; CLIENT *clnt; static int clnt_res; memset((char *)&clnt_res, 0, sizeof (clnt_res)); if (clnt_call(clnt, INITW, (xdrproc_t) xdr_void, (caddr_t) argp, (xdrproc_t) xdr_int, (caddr_t) &clnt_res, TIMEOUT)!= RPC_SUCCESS) return (NULL); return (&clnt_res);

4 Client code (rdict_clnt.c) int * insertw_1(argp, clnt) char **argp; CLIENT *clnt; static int clnt_res; memset((char *)&clnt_res, 0, sizeof (clnt_res)); if (clnt_call(clnt, INSERTW, (xdrproc_t) xdr_wrapstring, (caddr_t) argp, (xdrproc_t) xdr_int, (caddr_t) &clnt_res, TIMEOUT)!= RPC_SUCCESS) return (NULL); return (&clnt_res);

5 Client code (rdict_clnt.c) int * deletew_1(argp, clnt) char **argp; CLIENT *clnt; static int clnt_res; memset((char *)&clnt_res, 0, sizeof (clnt_res)); if (clnt_call(clnt, DELETEW, (xdrproc_t) xdr_wrapstring, (caddr_t) argp, (xdrproc_t) xdr_int, (caddr_t) &clnt_res, TIMEOUT)!= RPC_SUCCESS) return (NULL); return (&clnt_res);

6 Client code (rdict_clnt.c) int * lookupw_1(argp, clnt) char **argp; CLIENT *clnt; static int clnt_res; memset((char *)&clnt_res, 0, sizeof (clnt_res)); if (clnt_call(clnt, LOOKUPW, (xdrproc_t) xdr_wrapstring, (caddr_t) argp, (xdrproc_t) xdr_int, (caddr_t) &clnt_res, TIMEOUT)!= RPC_SUCCESS) return (NULL); return (&clnt_res);

7 Server Code (rdict_svc.c) * Please do not edit this file. * It was generated using rpcgen. */ #include "rdict.h" #include <stdio.h> #include <stdlib.h> /* getenv, exit */ #include <signal.h> #include <sys/types.h> #include <memory.h> #include <stropts.h> #include <netconfig.h> #include <sys/resource.h> /* rlimit */ #include <syslog.h> #ifdef DEBUG #define #endif RPC_SVC_FG #define _RPCSVC_CLOSEDOWN 120 static int _rpcpmstart; /* Started by a port monitor? */

8 Server Code (rdict_svc.c) /* States a server can be in wrt request */ #define _IDLE 0 #define _SERVED 1 static int _rpcsvcstate = _IDLE; /* Set when a request is serviced */ static int _rpcsvccount = 0; /* Number of requests being serviced */ static void _msgout(msg) char *msg; #ifdef RPC_SVC_FG if (_rpcpmstart) syslog(log_err, msg); else (void) fprintf(stderr, "%s\n", msg); #else syslog(log_err, msg); #endif

9 Server Code (rdict_svc.c) static void closedown(sig) int sig; if (_rpcsvcstate == _IDLE && _rpcsvccount == 0) int size; int i, openfd = 0; else size = svc_max_pollfd; for (i = 0; i < size && openfd < 2; i++) if (svc_pollfd[i].fd >= 0) openfd++; if (openfd <= 1) exit(0); _rpcsvcstate = _IDLE; (void) signal(sigalrm, (void(*)()) closedown); (void) alarm(_rpcsvc_closedown/2);

10 Server Code (rdict_svc.c) static void rdictprog_1(rqstp, transp) struct svc_req *rqstp; register SVCXPRT *transp; union char *insertw_1_arg; char *deletew_1_arg; char *lookupw_1_arg; argument; char *result; bool_t (*_xdr_argument)(), (*_xdr_result)(); char *(*local)(); _rpcsvccount++; switch (rqstp->rq_proc) case NULLPROC: (void) svc_sendreply(transp, xdr_void, (char *)NULL); _rpcsvccount--; _rpcsvcstate = _SERVED; return;

11 Server Code (rdict_svc.c) case INITW: _xdr_argument = xdr_void; _xdr_result = xdr_int; local = (char *(*)()) initw_1; break; case INSERTW: _xdr_argument = xdr_wrapstring; _xdr_result = xdr_int; local = (char *(*)()) insertw_1; break; case DELETEW: _xdr_argument = xdr_wrapstring; _xdr_result = xdr_int; local = (char *(*)()) deletew_1; break; case LOOKUPW: _xdr_argument = xdr_wrapstring; _xdr_result = xdr_int; local = (char *(*)()) lookupw_1; break;

12 Server Code (rdict_svc.c) default: svcerr_noproc(transp); _rpcsvccount--; _rpcsvcstate = _SERVED; return;

13 Server Code (rdict_svc.c) (void) memset((char *)&argument, 0, sizeof (argument)); if (!svc_getargs(transp, _xdr_argument, (caddr_t) &argument)) svcerr_decode(transp); _rpcsvccount--; _rpcsvcstate = _SERVED; return; result = (*local)(&argument, rqstp); if (result!= NULL &&!svc_sendreply(transp, _xdr_result, result)) svcerr_systemerr(transp); if (!svc_freeargs(transp, _xdr_argument, (caddr_t) &argument)) _msgout("unable to free arguments"); exit(1); _rpcsvccount--; _rpcsvcstate = _SERVED; return;

14 Server Code (rdict_svc.c) main() pid_t pid; int i; (void) sigset(sigpipe, SIG_IGN); /* * If stdin looks like a TLI endpoint, we assume * that we were started by a port monitor. If * t_getstate fails with TBADF, this is not a * TLI endpoint. */ if (t_getstate(0)!= -1 t_errno!= TBADF) char *netid; struct netconfig *nconf = NULL; SVCXPRT *transp; int pmclose; _rpcpmstart = 1; openlog("rdict", LOG_PID, LOG_DAEMON);

15 Server Code (rdict_svc.c) if ((netid = getenv("nlsprovider")) == NULL) /* started from inetd */ pmclose = 1; else if ((nconf = getnetconfigent(netid)) == NULL) _msgout("cannot get transport info"); RDICTVERS)."); pmclose = (t_getstate(0)!= T_DATAXFER); if ((transp = svc_tli_create(0, nconf, NULL, 0, 0)) == NULL) _msgout("cannot create server handle"); exit(1); if (nconf) freenetconfigent(nconf); if (!svc_reg(transp, RDICTPROG, RDICTVERS, rdictprog_1, 0)) _msgout("unable to register (RDICTPROG, exit(1);

16 Server Code (rdict_svc.c) if (pmclose) (void) signal(sigalrm, (void(*)()) closedown); (void) alarm(_rpcsvc_closedown/2); svc_run(); exit(1); /* NOTREACHED */ else #ifndef RPC_SVC_FG int size; struct rlimit rl; pid = fork(); if (pid < 0) perror("cannot fork"); exit(1);

17 Server Code (rdict_svc.c) #endif if (pid) exit(0); rl.rlim_max = 0; getrlimit(rlimit_nofile, &rl); if ((size = rl.rlim_max) == 0) exit(1); for (i = 0; i < size; i++) (void) close(i); i = open("/dev/null", 2); (void) dup2(i, 1); (void) dup2(i, 2); setsid(); openlog("rdict", LOG_PID, LOG_DAEMON);

18 Server Code (rdict_svc.c) if (!svc_create(rdictprog_1, RDICTPROG, RDICTVERS, "netpath")) _msgout("unable to create (RDICTPROG, RDICTVERS) for netpath."); exit(1); svc_run(); _msgout("svc_run returned"); exit(1); /* NOTREACHED */

19 Server Code (rdict_svc.c) Rpcgen produces the file rdict_svc.c The file contain the main program that execute when the server begins. It obtains a protocol port, registers the RPC program with the port mapper, and then waits to receive RPC calls. cc c rdict_clnt.c cc c rdict_svc.c cc c rdict_xdr.c

20 Step 5 Write Stub Interface Procedures On the client side, it calls interface procedures using the same procedure names and argument types as the original program (non RPC). On the server side, the interface routines accept calls from the communication stubs that RPC produces, and pass control to the procedure Must translate from XDR to native

21 Rdict_cif.c /* rdict_cif.c - initw, insertw, deletew, lookupw */ #include <rpc/rpc.h> #include <stdio.h> #include "rdict.h" /* Client-side stub interface routines written by programmer */ extern CLIENT *handle; /* handle for remote procedure */ static int *ret; /* tmp storage for return code */ /* * initw - client interface routine that calls initw_1 * */ int initw() ret = initw_1(0, handle); return ret==0? 0 : *ret;

22 Rdict_cif.c /* * insertw - client interface routine that calls insertw_1 * */ int insertw(char *word) char **arg; /* pointer to argument */ arg = &word; ret = insertw_1(arg, handle); return ret==0? 0 : *ret; /* * deletew - client interface routine that calls deletew_1 * */ int deletew(char *word) char **arg; /* pointer to argument */ arg = &word; ret = deletew_1(arg, handle); return ret==0? 0 : *ret;

23 Rdict_cif.c /* * lookupw - client interface routine that calls lookupw_1 * */ int lookupw(char *word) char **arg; /* pointer to argument */ arg = &word; ret = lookupw_1(arg, handle); return ret==0? 0 : *ret;

24 Rdict_sif.c /* rdict_sif.c - init_1, insert_1, delete_1, lookup_1 */ #include <rpc/rpc.h> #include "rdict.h" /* Server-side stub inteface routines written by programmer */ static int retcode; /* * insertw_1 - server side interface to remote procedure insertw * */ int * insertw_1(char **w) retcode = insertw(*w); return &retcode;

25 Rdict_sif.c /* * initw_1 - server side interface to remote procedure initw * */ int * initw_1() retcode = initw(); return &retcode; /* * deletew_1 - server side interface to remote procedure deletew * */ int * deletew_1(char **w) retcode = deletew(*w); return &retcode;

26 Rdict_sif.c /* * lookupw_1 - server side interface to remote procedure lookupw * */ int * lookupw_1(char **w) retcode = lookupw(*w); return &retcode;

27 Step 6 We need some changes in the origianl rdict.c program

28 Rdict.c /* rdict.c - main, nextin */ #include <rpc/rpc.h> #include <stdlib.h> #include <stdio.h> #include <ctype.h> #include "rdict.h" #define MAXWORD 50 /* maximum length of a command or word */ #define RMACHINE "localhost" /* name of remote machine */ CLIENT *handle; /* handle for remote procedure */ int int nextin(char *cmd, char *word), initw(), insertw(char *word); deletew(char *word), lookupw(char *word);

29 Rdict.c /* * main - insert, delete, or lookup words in a dictionary as specified * */ int main(int argc, char *argv[]) char word[maxword+1]; /* space to hold word from input line */ char cmd; int wrdlen; /* length of input word */ /* set up connection for remote procedure call */ handle = clnt_create(rmachine, RDICTPROG, RDICTVERS, "tcp"); if (handle == 0) printf("could not contact remote program.\n"); exit(1);

30 Rdict.c while (1) wrdlen = nextin(&cmd, word); if (wrdlen < 0) exit(0); switch (cmd) case 'I': /* "initialize" */ initw(); printf("dictionary initialized to empty.\n"); break; case 'i': /* "insert" */ insertw(word); printf("%s inserted.\n",word); break; case 'd': /* "delete" */ if (deletew(word)) printf("%s deleted.\n",word); else printf("%s not found.\n",word); break;

31 Rdict.c case 'l': /* "lookup" */ if (lookupw(word)) printf("%s was found.\n",word); else printf("%s was not found.\n",word); break; case 'q': /* quit */ printf("program quits.\n"); exit(0); default: /* illegal input */ printf("command %c invalid.\n", cmd); break;

32 Rdict.c /* * nextin - read a command and (possibly) a word from the next input line * */ int nextin(char *cmd, char *word) int i, ch; ch = getc(stdin); while (isspace(ch)) ch = getc(stdin); if (ch == EOF) return -1; *cmd = (char) ch; ch = getc(stdin); while (isspace(ch)) ch = getc(stdin); if (ch == EOF) return -1; if (ch == '\n') return 0; i = 0;

33 Rdict.c while (!isspace(ch)) if (++i > MAXWORD) printf("error: word too long.\n"); exit(1); *word++ = ch; ch = getc(stdin); *word = \0 ; return i;

34 Step 6 Now compile the client program cc c rdict.c cc rdict_cif.c cc o rdict rdict.o rdict_clnt.o rdict_xdr.o rdict_cif.o lnsl -lsocket

35 Step 7 Now, the server program It contains all the procedures we need.

36 Rdict_srp.c /* rdict_srp.c - initw, insertw, deletew, lookupw */ #include <rpc/rpc.h> #include "rdict.h" /* Server-side remote procedures and the global data they use */ char dict[dictsiz][maxword+1];/* storage for a dictionary of words */ int nwords = 0; /* number of words in the dictionary */ /* * initw - initialize the dictionary to contain no words at all * */ int initw() nwords = 0; return 1;

37 Rdict_srp.c /* * insertw - insert a word in the dictionary * */ int insertw(char *word) strcpy(dict[nwords], word); nwords++; return nwords; /* * deletew - delete a word from the dictionary * */ 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;

38 Rdict_srp.c /* * lookupw - look up a word in the dictionary * */ int lookupw(char *word) int i; for (i=0 ; i<nwords ; i++) if (strcmp(word, dict[i]) == 0) return 1; return 0;

39 Step 7 Compile and run the server program cc c rdict_srp.c cc o rdictd rdict_svc.o rdict_xdr.o rdict_sif.o rdict_srp.o lnsl lsocket

40 Step 8 Run the server on the remote machine./rdictd & There is a makefile that you can use to handle all the compilation You have to specify instead of localhost the name of the machine the server will be running on