Linux rpc 远程访问,我是这样学习Linux下C语言编程的-RPC远程调用编程

我是这样学习Linux下C语言编程的-RPC远程调用编程

在查看libc6-dev软件包提供的工具(用 dpkg -L libc6-dev 命令)的时候,发现此软件包提供了一个有用的工具rpcgen命令。

通过rpcgen的man手册看到此工具的作用是把RPC源程序编译成C语言源程序,从而轻松实现远程过程调用。

下面的例子程序的作用是客户端程序取中心服务器上时间的,编程过程如下:

先编写一个 “ RPC 语言 ” ( RPC Language ( Remote Procedure Call Language ) ) 的源文件 test.x ,文件后缀名为 x 。

源代码如下:

program TESTPROG {

version VERSION {

string TEST(string) = 1;

} = 1;

} = 87654321;说明:这里数字87654321是RPC程序编号,还有VERSION版本号为1,都是给RPC服务程序用的。同时指定程序接受一个字符串参数。

运行这个命令:

rpcgen test.x将生成三个源文件:

test_clnt.c test.h test_svc.c源文件test_clnt.c 内容如下:

/*

* Please do not edit this file.

* It was generated using rpcgen.

*/

#include >memory.h< /* for memset */

#include "test.h"

/* Default timeout can be changed using clnt_control() */

static struct timeval TIMEOUT = { 25, 0 };

char **

test_1(char **argp, CLIENT *clnt)

{

static char *clnt_res;

memset((char *)&clnt_res, 0, sizeof(clnt_res));

if (clnt_call (clnt, TEST,

(xdrproc_t) xdr_wrapstring, (caddr_t) argp,

(xdrproc_t) xdr_wrapstring, (caddr_t) &clnt_res,

TIMEOUT) != RPC_SUCCESS) {

return (NULL);

}

return (&clnt_res);

}说明:这是一个客户端调用函数,即客户端代码需要用到此函数。

源文件test.h内容如下:

/*

* Please do not edit this file.

* It was generated using rpcgen.

*/

#ifndef _TEST_H_RPCGEN

#define _TEST_H_RPCGEN

#include >rpc/rpc.h<

#ifdef __cplusplus

extern "C" {

#endif

#define TESTPROG 87654321

#define VERSION 1

#if defined(__STDC__) || defined(__cplusplus)

#define TEST 1

extern char ** test_1(char **, CLIENT *);

extern char ** test_1_svc(char **, struct svc_req *);

extern int testprog_1_freeresult (SVCXPRT *, xdrproc_t, caddr_t);

#else /* K&R C */

#define TEST 1

extern char ** test_1();

extern char ** test_1_svc();

extern int testprog_1_freeresult ();

#endif /* K&R C */

#ifdef __cplusplus

}

#endif

#endif /* !_TEST_H_RPCGEN */说明:这里定义了一些公用头文件。

源文件test_svc.c内容如下:

/*

* Please do not edit this file.

* It was generated using rpcgen.

*/

#include "test.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

static void

testprog_1(struct svc_req *rqstp, register SVCXPRT *transp)

{

union {

char *test_1_arg;

} argument;

char *result;

xdrproc_t _xdr_argument, _xdr_result;

char *(*local)(char *, struct svc_req *);

switch (rqstp- case NULLPROC:

(void) svc_sendreply (transp, (xdrproc_t) xdr_void, (char *)NULL);

return;

case TEST:

_xdr_argument = (xdrproc_t) xdr_wrapstring;

_xdr_result = (xdrproc_t) xdr_wrapstring;

local = (char *(*)(char *, struct svc_req *)) test_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;

}

result = (*local)((char *)&argument, rqstp);

if (result != NULL && !svc_sendreply(transp, (xdrproc_t) _xdr_result, result)) {

svcerr_systemerr (transp);

}

if (!svc_freeargs (transp, (xdrproc_t) _xdr_argument, (caddr_t) &argument)) {

fprintf (stderr, "%s", "unable to free arguments");

exit (1);

}

return;

}

int

main (int argc, char **argv)

{

register SVCXPRT *transp;

pmap_unset (TESTPROG, VERSION);

transp = svcudp_create(RPC_ANYSOCK);

if (transp == NULL) {

fprintf (stderr, "%s", "cannot create udp service.");

exit(1);

}

if (!svc_register(transp, TESTPROG, VERSION, testprog_1, IPPROTO_UDP)) {

fprintf (stderr, "%s", "unable to register (TESTPROG, VERSION, 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, TESTPROG, VERSION, testprog_1, IPPROTO_TCP)) {

fprintf (stderr, "%s", "unable to register (TESTPROG, VERSION, tcp).");

exit(1);

}

svc_run ();

fprintf (stderr, "%s", "svc_run returned");

exit (1);

/* NOTREACHED */

}说明:这是一个标准的服务器端代码。

运行下列命令生成一个客户端源文件test_client.c:

rpcgen -Sc -o test_client.c test.x源代码test_client.c如下:

/*

* 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 "test.h"

void

testprog_1(char *host)

{

CLIENT *clnt;

char * *result_1;

char * test_1_arg;

#ifndef DEBUG

clnt = clnt_create (host, TESTPROG, VERSION, "udp");

if (clnt == NULL) {

clnt_pcreateerror (host);

exit (1);

}

#endif /* DEBUG */

result_1 = test_1(&test_1_arg, clnt);

if (result_1 == (char **) NULL) {

clnt_perror (clnt, "call failed");

}

#ifndef DEBUG

clnt_destroy (clnt);

#endif /* DEBUG */

}

int

main (int argc, char *argv[])

{

char *host;

if (argc > 2) {

printf ("usage: %s server_host/n", argv[0]);

exit (1);

}

host = argv[1];

testprog_1 (host);

exit (0);

}运行这个命令生成服务端源文件test_srv_func.c:

rpcgen -Ss -o test_srv_func.c test.x源文件test_srv_func.c内容如下:

/*

* 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 "test.h"

char **

test_1_svc(char **argp, struct svc_req *rqstp)

{

static char * result;

/*

* insert server code here

*/

return &result;

}说明:这是一个服务器端调用的函数。

至此,我们就可以编译生成程序来运行了。

用下面的命令编译生成服务端程序test_server:

gcc -Wall -o test_server test_clnt.c test_srv_func.c test_svc.c用下面的命令编译生成客户端程序test_client:

gcc -Wall -o test_client test_client.c test_clnt.c运行下列命令启动服务端:

./test_server运行下列命令可以进行客户端测试:

./test_client 127.0.0.1但是由于现的的服务端没有处理客户端请求,所以这样的程序还不能完成任何工作。

下面我们先给服务端程序加上代码,使这个服务器能完成一定的工作。即修改 test_srv_func.c ,在 “ * insert server code here ” 后面加上取时间的代码,即修改后的 test_srv_func.c 代码如下:

/*

* 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 >time.h<

#include "test.h"

char **

test_1_svc(char **argp, struct svc_req *rqstp)

{

static char * result;

static char tmp_char[128];

time_t rawtime;

/*

* insert server code here

*/

if( time(&rawtime) == ((time_t)-1) ) {

strcpy(tmp_char, "Error");

result = tmp_char;

return &result;

}

sprintf(tmp_char, "服务器当前时间是 :%s", ctime(&rawtime));

result = tmp_char;

return &result;

}再修改客户端代码以显示服务器端返回的内容,即修改test_client.c源文件,只需要修改其中的函数testprog_1,修改后如下:

void

testprog_1(char *host)

{

CLIENT *clnt;

char * *result_1;

char * test_1_arg;

test_1_arg = (char *)malloc(128);

#ifndef DEBUG

clnt = clnt_create (host, TESTPROG, VERSION, "udp");

if (clnt == NULL) {

clnt_pcreateerror (host);

exit (1);

}

#endif /* DEBUG */

result_1 = test_1(&test_1_arg, clnt);

if (result_1 == (char **) NULL) {

clnt_perror (clnt, "call failed");

}

if (strcmp(*result_1, "Error") == 0) {

fprintf(stderr, "%s: could not get the time/n", host);

exit(1);

}

printf("收到消息 ... %s/n", *result_1);

#ifndef DEBUG

clnt_destroy (clnt);

#endif /* DEBUG */

}重新运行上述编译命令编译生成程序:

gcc -Wall -o test_server test_clnt.c test_srv_func.c test_svc.c

gcc -Wall -o test_client test_client.c test_clnt.c启动服务端程序后运行客户端程序如下:

./test_client 127.0.0.1

收到消息 ... 服务器当前时间是 :Tue Feb 27 11:45:21 2007为了省略每次输入gcc命令的麻烦,也为了维护我们的工程,可以运行下列命令生成一个Makefile文件:

rpcgen -Sm test.x < Makefile生成的Makefile内容如下:

# This is a template Makefile generated by rpcgen

# Parameters

CLIENT = test_client

SERVER = test_server

SOURCES_CLNT.c =

SOURCES_CLNT.h =

SOURCES_SVC.c =

SOURCES_SVC.h =

SOURCES.x = test.x

TARGETS_SVC.c =

TARGETS_CLNT.c =

TARGETS =

OBJECTS_CLNT = $(SOURCES_CLNT.c:%.c=%.o) $(TARGETS_CLNT.c:%.c=%.o)

OBJECTS_SVC = $(SOURCES_SVC.c:%.c=%.o) $(TARGETS_SVC.c:%.c=%.o)

# Compiler flags

CFLAGS += -g

LDLIBS += -lnsl

RPCGENFLAGS =

# Targets

all : $(CLIENT) $(SERVER)

$(TARGETS) : $(SOURCES.x)

rpcgen $(RPCGENFLAGS) $(SOURCES.x)

$(OBJECTS_CLNT) : $(SOURCES_CLNT.c) $(SOURCES_CLNT.h) $(TARGETS_CLNT.c)

$(OBJECTS_SVC) : $(SOURCES_SVC.c) $(SOURCES_SVC.h) $(TARGETS_SVC.c)

$(CLIENT) : $(OBJECTS_CLNT)

$(LINK.c) -o $(CLIENT) $(OBJECTS_CLNT) $(LDLIBS)

$(SERVER) : $(OBJECTS_SVC)

$(LINK.c) -o $(SERVER) $(OBJECTS_SVC) $(LDLIBS)

clean:

$(RM) core $(TARGETS) $(OBJECTS_CLNT) $(OBJECTS_SVC) $(CLIENT) $(SERVER)由于我们手工生成了源文件,所以要修改一下这个Makefile,修改后如下:

# This is a template Makefile generated by rpcgen

# Parameters

CLIENT = test_client

SERVER = test_server

SOURCES_CLNT.c =

SOURCES_CLNT.h =

SOURCES_SVC.c =

SOURCES_SVC.h =

SOURCES.x = test.x

TARGETS_SVC.c = test_clnt.c test_srv_func.c test_svc.c

TARGETS_CLNT.c = test_clnt.c test_client.c

TARGETS = test.h test_clnt.c test_svc.c

OBJECTS_CLNT = $(SOURCES_CLNT.c:%.c=%.o) $(TARGETS_CLNT.c:%.c=%.o)

OBJECTS_SVC = $(SOURCES_SVC.c:%.c=%.o) $(TARGETS_SVC.c:%.c=%.o)

# Compiler flags

CFLAGS += -g

LDLIBS += -lnsl

RPCGENFLAGS =

# Targets

all : $(CLIENT) $(SERVER)

$(TARGETS) : $(SOURCES.x)

rpcgen $(RPCGENFLAGS) $(SOURCES.x)

$(OBJECTS_CLNT) : $(SOURCES_CLNT.c) $(SOURCES_CLNT.h) $(TARGETS_CLNT.c)

$(OBJECTS_SVC) : $(SOURCES_SVC.c) $(SOURCES_SVC.h) $(TARGETS_SVC.c)

$(CLIENT) : $(OBJECTS_CLNT)

$(LINK.c) -o $(CLIENT) $(OBJECTS_CLNT) $(LDLIBS)

$(SERVER) : $(OBJECTS_SVC)

$(LINK.c) -o $(SERVER) $(OBJECTS_SVC) $(LDLIBS)

clean:

$(RM) core $(TARGETS) $(OBJECTS_CLNT) $(OBJECTS_SVC) $(CLIENT) $(SERVER) *~

【作者: Liberal】【访问统计:】【2007年10月26日 星期五 19:06】【注册】【打印】

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