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[求助]sockets编程遇到的问题
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发表于: 2007-8-27 11:25
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小弟刚学习sockets编程，写了个小程序以实现类似telnet功能。
思路如下：
客户端接受命令并传给服务端，服务端使用system函数运行，
并利用cmd下的">"重定向符号将结果输入到"exeinf"文件中，
最后再将文件内容读入缓冲区发送到客户端以实现回现功能。
测试时发现如下问题：
1.客户端只能发送一次命令
2.发送“net user” 可以正确执行，但是发送“net localgroup admininstrators”
以及dir等命令不能正确执行（没回显）
读了几遍代码没找出原因，还望各位指教一下，谢谢;)
编译环境：xp & vc++6.0
代码如下：
//client.cpp
#include <stdio.h>
#include <winsock.h>
#include <windows.h>
#pragma comment(lib,"Ws2_32")
#define PORT 2007
#define MAXDATASIZE 1024 /* the max charectors recived */
void GL_logo()
{
printf("study sockets.\n");
}
int main(int argc, char *argv[])
{
LoadLibrary("msvcrt.dll");
int sockfd;
int num; //control the loop
struct sockaddr_in their_addr;
char Cmd[128]; //cmd buf which contens the command
char buf[MAXDATASIZE];
char cinf; //read file buffer size of which is char
system("cls");
GL_logo();
if (argc != 2)
{
printf(" Usage: %s ip\n",argv[0]);
exit(1);
}
WSADATA ws;
WSAStartup(MAKEWORD(2,2),&ws); //init Windows Socket Dll
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
printf("[+]Initialize socket error...\n");
exit(1);
}
else
printf("[+]Initialize sockets successful...\n");
//connect to server
their_addr.sin_family = AF_INET; /* protol isINET*/
their_addr.sin_port = htons(PORT); /* connect to server ports*/
their_addr.sin_addr.s_addr = inet_addr(argv[1]); /* server IP*/
if (connect(sockfd, (struct sockaddr *)&their_addr,sizeof(struct sockaddr)) == -1)
{
printf("[-]Connet error...\n");
closesocket(sockfd);
exit(1);
}
else
printf("[-]IConnet successful...\n");
//gain the command
while(1)
{
printf("[+]Please input the command:");
num=0;
while((cinf=getchar())!='\n')
{
Cmd[num]=cinf;
num++;
}
Cmd[num]='\0';
if(Cmd=="GL")
{
break;
}
printf("[-]The command you input is:\"%s\"\n",Cmd);
sprintf(buf,"%s > exeinf",Cmd);
//send command
if (send(sockfd, buf, 14, 0) == -1)
{
printf("[+]Send error...");
closesocket(sockfd);
exit(1);
}
printf("[+]Send ok...\n");
//stop here
//recive and print the message
if ((num=recv(sockfd, buf, MAXDATASIZE, 0)) == -1)
{
//if error then exit
printf("[-]Recived error...\n");
closesocket(sockfd);
exit(1);
}
else
printf("[-]Recived successful...\n");
buf[num] = '\0';
printf("[^GL^]The result of \"%s\" is: \n%s\n",Cmd,buf);
}
closesocket(sockfd);
return 0;
}
_____________________________________________________________________________
//server.cpp
#include <stdio.h>
#include <winsock.h>
#pragma comment(lib,"Ws2_32")
#define MYPORT 2007 /*defind the port*/
#define BACKLOG 14 /*the num of connect*/
int main()
{
int sockfd, new_fd;
struct sockaddr_in my_addr;
struct sockaddr_in their_addr;
int sin_size;
char Cmd[128]; //cmd buf which contens the command
char buf[1024];
char cinf; // buffer
int num;
FILE *file_cmd;
WSADATA ws;
WSAStartup(MAKEWORD(2,2),&ws);
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
//creat errror then exit
printf("socket error\n");
exit(1);
}
//bind本机的MYPORT端口
my_addr.sin_family = AF_INET; /* protol is INET*/
my_addr.sin_port = htons(MYPORT); /* bind MYPORT */
my_addr.sin_addr.s_addr = INADDR_ANY; /* MYIP */
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr))== -1)
{
//bind error then exit
printf("bind error\n");
closesocket(sockfd);
exit(1);
}
//listen ports
if (listen(sockfd, BACKLOG) == -1)
{
//listen error then exit
printf("listen error\n");
closesocket(sockfd);
exit(1);
}
printf("listen...");
//wating for connect to
sin_size = sizeof(struct sockaddr_in);
if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1)
{
printf("accept error\n");
closesocket(sockfd);
exit(1);
}
printf("\naccept!\n");
while(1)
{
//recive the command
if ((num=recv(new_fd, Cmd, 128, 0)) != -1)
{
printf("[+]Recived successful...\n");
//buf[num] = '\0';
sprintf(buf,"%s > exeinf",Cmd);
if( (file_cmd = fopen("exeinf", "w+" )) != NULL )
{
fclose( file_cmd );
system(buf);
}
else
{
printf("built fiel errror");
closesocket(sockfd);
closesocket(new_fd);
}
//putout to the file
if( (file_cmd = fopen("exeinf", "r" )) != NULL )
{
cinf=fgetc(file_cmd);
num=0;
while(cinf!=EOF)
{
buf[num]=cinf;
num=num++;
cinf=fgetc(file_cmd);
}
buf[num]='\0';
printf("the result is:\n %s\n",buf);
}
else
{
printf("can't read the file\n");
fclose( file_cmd );
}
//send the exec result
if (send(new_fd, buf, num, 0) == -1)
{
printf("send error");
closesocket(sockfd);
closesocket(new_fd);
exit(1);
}
printf("send ok!\n");
}
//recive error then exit
else
{
printf("[+]Recived error...\n");
exit(1);
}
}
closesocket(new_fd);
closesocket(sockfd);
return 0;
}
思路如下：
客户端接受命令并传给服务端，服务端使用system函数运行，
并利用cmd下的">"重定向符号将结果输入到"exeinf"文件中，
最后再将文件内容读入缓冲区发送到客户端以实现回现功能。
测试时发现如下问题：
1.客户端只能发送一次命令
2.发送“net user” 可以正确执行，但是发送“net localgroup admininstrators”
以及dir等命令不能正确执行（没回显）
读了几遍代码没找出原因，还望各位指教一下，谢谢;)
编译环境：xp & vc++6.0
代码如下：
//client.cpp
#include <stdio.h>
#include <winsock.h>
#include <windows.h>
#pragma comment(lib,"Ws2_32")
#define PORT 2007
#define MAXDATASIZE 1024 /* the max charectors recived */
void GL_logo()
{
printf("study sockets.\n");
}
int main(int argc, char *argv[])
{
LoadLibrary("msvcrt.dll");
int sockfd;
int num; //control the loop
struct sockaddr_in their_addr;
char Cmd[128]; //cmd buf which contens the command
char buf[MAXDATASIZE];
char cinf; //read file buffer size of which is char
system("cls");
GL_logo();
if (argc != 2)
{
printf(" Usage: %s ip\n",argv[0]);
exit(1);
}
WSADATA ws;
WSAStartup(MAKEWORD(2,2),&ws); //init Windows Socket Dll
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
printf("[+]Initialize socket error...\n");
exit(1);
}
else
printf("[+]Initialize sockets successful...\n");
//connect to server
their_addr.sin_family = AF_INET; /* protol isINET*/
their_addr.sin_port = htons(PORT); /* connect to server ports*/
their_addr.sin_addr.s_addr = inet_addr(argv[1]); /* server IP*/
if (connect(sockfd, (struct sockaddr *)&their_addr,sizeof(struct sockaddr)) == -1)
{
printf("[-]Connet error...\n");
closesocket(sockfd);
exit(1);
}
else
printf("[-]IConnet successful...\n");
//gain the command
while(1)
{
printf("[+]Please input the command:");
num=0;
while((cinf=getchar())!='\n')
{
Cmd[num]=cinf;
num++;
}
Cmd[num]='\0';
if(Cmd=="GL")
{
break;
}
printf("[-]The command you input is:\"%s\"\n",Cmd);
sprintf(buf,"%s > exeinf",Cmd);
//send command
if (send(sockfd, buf, 14, 0) == -1)
{
printf("[+]Send error...");
closesocket(sockfd);
exit(1);
}
printf("[+]Send ok...\n");
//stop here
//recive and print the message
if ((num=recv(sockfd, buf, MAXDATASIZE, 0)) == -1)
{
//if error then exit
printf("[-]Recived error...\n");
closesocket(sockfd);
exit(1);
}
else
printf("[-]Recived successful...\n");
buf[num] = '\0';
printf("[^GL^]The result of \"%s\" is: \n%s\n",Cmd,buf);
}
closesocket(sockfd);
return 0;
}
_____________________________________________________________________________
//server.cpp
#include <stdio.h>
#include <winsock.h>
#pragma comment(lib,"Ws2_32")
#define MYPORT 2007 /*defind the port*/
#define BACKLOG 14 /*the num of connect*/
int main()
{
int sockfd, new_fd;
struct sockaddr_in my_addr;
struct sockaddr_in their_addr;
int sin_size;
char Cmd[128]; //cmd buf which contens the command
char buf[1024];
char cinf; // buffer
int num;
FILE *file_cmd;
WSADATA ws;
WSAStartup(MAKEWORD(2,2),&ws);
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
//creat errror then exit
printf("socket error\n");
exit(1);
}
//bind本机的MYPORT端口
my_addr.sin_family = AF_INET; /* protol is INET*/
my_addr.sin_port = htons(MYPORT); /* bind MYPORT */
my_addr.sin_addr.s_addr = INADDR_ANY; /* MYIP */
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr))== -1)
{
//bind error then exit
printf("bind error\n");
closesocket(sockfd);
exit(1);
}
//listen ports
if (listen(sockfd, BACKLOG) == -1)
{
//listen error then exit
printf("listen error\n");
closesocket(sockfd);
exit(1);
}
printf("listen...");
//wating for connect to
sin_size = sizeof(struct sockaddr_in);
if ((new_fd = accept(sockfd, (struct sockaddr *)&their_addr, &sin_size)) == -1)
{
printf("accept error\n");
closesocket(sockfd);
exit(1);
}
printf("\naccept!\n");
while(1)
{
//recive the command
if ((num=recv(new_fd, Cmd, 128, 0)) != -1)
{
printf("[+]Recived successful...\n");
//buf[num] = '\0';
sprintf(buf,"%s > exeinf",Cmd);
if( (file_cmd = fopen("exeinf", "w+" )) != NULL )
{
fclose( file_cmd );
system(buf);
}
else
{
printf("built fiel errror");
closesocket(sockfd);
closesocket(new_fd);
}
//putout to the file
if( (file_cmd = fopen("exeinf", "r" )) != NULL )
{
cinf=fgetc(file_cmd);
num=0;
while(cinf!=EOF)
{
buf[num]=cinf;
num=num++;
cinf=fgetc(file_cmd);
}
buf[num]='\0';
printf("the result is:\n %s\n",buf);
}
else
{
printf("can't read the file\n");
fclose( file_cmd );
}
//send the exec result
if (send(new_fd, buf, num, 0) == -1)
{
printf("send error");
closesocket(sockfd);
closesocket(new_fd);
exit(1);
}
printf("send ok!\n");
}
//recive error then exit
else
{
printf("[+]Recived error...\n");
exit(1);
}
}
closesocket(new_fd);
closesocket(sockfd);
return 0;
}
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见笑了
小弟刚接触socket， 这是处女作 哈哈 加之以前也没写程序的经验 献丑了
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呵呵
学习了 好惭愧 努力中...... 
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