客戶端服務器編程 - 緩衝區寫入

我想開發C++中，客戶端是TCP回顯客戶機，而服務器是使用單個進程（使用select系統調用）的TCP併發服務器的客戶端服務器程序。但是我是成功的發展，但與寫入緩衝區的問題。客戶端服務器編程 - 緩衝區寫入

服務器正在寫一些額外的字符從以前的消息後一些消息交換賭客戶端和服務器，在開始工作正常的一些消息互換。我沒有得到爲什麼會這樣？

//客戶端代碼

#include <stdlib.h> 
#include <unistd.h> 
#include <stdio.h> 
#include <netdb.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <string.h> 
#include <arpa/inet.h> 
#include <iostream> 
using namespace std; 

#define MAXLINE 4096 /*max text line length*/ 
#define srv_PORT 3000 /*port*/ 

int main(int argc,char **argv) 
{ 
int sockfd; 
struct sockaddr_in srvaddr; 
int sendchars,recvchar; 
char buf[MAXLINE]; 


if (argc !=2) 
{ 
    cerr<<"Usage: Femto: <IP address of the srv"<<endl; 
    exit(1); 
} 

//Create a socket for the client 

if ((sockfd = socket (AF_INET, SOCK_STREAM, 0)) <0) 
{ 
    cerr<<"Problem in creating the socket"<<endl; 
    exit(1); 
} 

//Creation of the socket 

memset(&srvaddr, 0, sizeof(srvaddr)); 
srvaddr.sin_family = AF_INET; 
srvaddr.sin_addr.s_addr= inet_addr(argv[1]); 
srvaddr.sin_port = htons(srv_PORT); 

//Connection of the client to the socket 
if (connect(sockfd, (struct sockaddr *) &srvaddr, sizeof(srvaddr))<0) 
{ 
    cerr<<"Problem in connecting to the server"<<endl; 
    exit(1); 
} 

while (fgets(buf,sizeof(buf), stdin)) 
{ 
    int n; 
    buf[MAXLINE]='\0'; 
    sendchars=strlen(buf); 
    write(sockfd,buf,sendchars); 

    for(recvchar=0;recvchar<sendchars;recvchar+=n) 
    { 
    n=read(sockfd,&buf[recvchar],sendchars-recvchar); 
    if(n<0) 
    { 
     cerr<<"Read faild"<<endl; 
     } 
    cout<< "String received from the FGW: "; 
    fputs(buf, stdout); 
} 
} 
}

//服務器代碼

#include <stdlib.h> 
#include <stdio.h> 
#include <sys/types.h> 
#include <sys/socket.h> 
#include <netinet/in.h> 
#include <string.h> 
#include <unistd.h> 
#include <iostream> 
#include <sys/select.h> 
#include <sys/time.h> 


using namespace std; 
#define MAXLINE 4096 /*max text line length*/ 
#define srv_PORT 3000 /*port*/ 
#define LISTENQ 65535 

int main (int argc, char **argv) 
{ 
int msock,ssock; 
fd_set rfds; 
fd_set afds; 
int fd,nfds; 
socklen_t client_len ; 


char buf[MAXLINE]; 
struct sockaddr_in clientaddr, srvaddr; 

if ((msock = socket (AF_INET, SOCK_STREAM, 0)) <0) 
{ 
cerr<<"Problem in creating the socket"<<endl; 
exit(1); 
    } 

srvaddr.sin_family = AF_INET; 
srvaddr.sin_addr.s_addr = htonl(INADDR_ANY); 
srvaddr.sin_port = htons(srv_PORT); 

bind (msock, (struct sockaddr *) &srvaddr, sizeof(srvaddr)); 

listen (msock, LISTENQ); 

nfds=getdtablesize(); 
FD_ZERO(&afds); 
FD_SET(msock,&afds); 

while(1) 
{ 
memcpy(&rfds,&afds,sizeof(rfds)); 
if(select(nfds,&rfds,(fd_set *)0,(fd_set *)0,(struct timeval *)0)<0) 
{ 
cerr<<"Error in select"; 
// exit(1); 
} 


if(FD_ISSET(msock,&rfds)) 
{ 
//int ssock; 
ssock= accept(msock,(struct sockaddr *)&clientaddr,&client_len); 
    if(ssock<0) 
    { 
    cerr<<"Accept error"; 
    } 
FD_SET(ssock,&afds); 
} 

for(fd=0;fd<nfds;++fd) 
    if(fd!=msock && FD_ISSET (fd,&rfds)) 
    { 
    int cc; 
    char buf[MAXLINE]; 
    cc=read(fd,buf,sizeof(buf)); 
    cout<<"String received from and resent to the client:"<<endl; 
     puts(buf); 
    if(cc<0) 
    { 
    cerr<<"Read error"<<endl; 
    exit(1); 
    } 
    if(cc && write(fd,buf,cc)<0) 
    { 
    cerr<<"Write error"<<endl; 
    exit(1); 
    } 
    } 
close(fd); 
FD_CLR(fd,&afds); 
    } 
}

來源

2014-01-31 user3168101

buf[MAXLINE]='\0';

是出界。這可能會隨時造成任何錯誤。你可以聲明

char buf[MAXLINE+1]

來源

2014-01-31 07:46:24

客戶端服務器編程 - 緩衝區寫入

回答

相關問題