socket编的简单服务器和客户机出现的奇怪问题

loveskyer

我最近在linux下用socket编写了一个通讯程序，主要是实现发送端可以向服务器端发送字符，但是问题出来了．我在自己机子上既当服务器又当客户机的时候可以顺利接受字符，但是我拿到机房用两台机子试的时候却显示连通了的（连通的情况下服务器自动向客户端返回hello），但是服务器收不到客户机发送的字符。我就觉得很奇怪。但是我用网线直接连两台机子的时候也可以接受。是不是和网线的连线有关系哦 ？难道是 路由器的原因？希望待机一起讨论共同进步

服务器程序：
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
int main(int argc,char *argv[])
{
char temp;
int a;
char resbuff[5];
int listensock,connsock;
struct sockaddr_in serveraddr;
const char buff[]="hello\r\n";
listensock=socket(AF_INET,SOCK_STREAM,0);
bzero(&serveraddr,sizeof(serveraddr));
serveraddr.sin_family=AF_INET;
serveraddr.sin_addr.s_addr=htonl(INADDR_ANY);
serveraddr.sin_port=htons(4114);
bind(listensock,(struct sockaddr*)&serveraddr,sizeof(serveraddr));
listen(listensock,1024);
connsock=accept(listensock,(struct sockaddr*)NULL,NULL);
send(connsock,buff,sizeof(buff),0);
recv(connsock,resbuff,1,0);
printf("%c\n",resbuff[0]);
while(resbuff[0]!='q')
{
switch(resbuff[0])
{
case'a':
printf("start the control module.\n");
system("gcc -O2 -g -Wall -DMODULE -D__KERNEL__ -I/usr/src/linux-2.4/include -c nrgcc.c");
system("gcc -O2 -g -Wall -DMODULE -D_KERNEL_ -I/usr/src/linux-2.4/include -c lgcc.c");
system("gcc -O2 -g -Wall -DMODULE -D__KERNEL__ -I/usr/src/linux-2.4/include -c nrgccf.c");
//system("insmod ./nrgcc.o >log1");
break;
case'b':
printf("connect out.\n");
recv(connsock,resbuff,1,0);
while(resbuff[0]!='1')
{printf("connect out.\n");
recv(connsock,resbuff,1,0);
}
break;

case'c':
printf("close the 80 source port.\n");
system("insmod ./nrgcc.o >log1");
break;

case'o':
printf("open the 80 source port.\n");
system("rmmod nrgcc >log3");
break;

case'f':
printf("filter the ICMP packet.\n");
system("insmod ./lgcc.o >log2");
break;

case'i':
printf("accept the ICMP packet.\n");
system("rmmod lgcc >log4");
break;

case't':
printf("close the FTP servers.\n");
system("insmod ./nrgccf.o >log5");
break;

case'p':
printf("start the FTP servers.\n");
system("rmmod nrgccf >log6");
break;

case'z':
printf("connect test.\n");
break;

case'r':
printf("all the control module has rmmod.\n");
system("rmmod nrgcc >log7");
system("rmmod nrgccf >log8");
system("rmmod lgcc >log9");
break;

default:
printf("---------------------.\n");
break;
}
recv(connsock,resbuff,1,0);
}
close(connsock);
close(listensock);
}

客户端程序：
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
int main(int argc,char **argv)
{
int i=0;
char w;
char sebuff[5];
char recvbuff[100];
int sockfd;
struct sockaddr_in serveraddr;
if(argc!=2){
printf("usage:echo ip");
exit(0);
}
sockfd=socket(AF_INET,SOCK_STREAM,0);
bzero(&serveraddr,sizeof(serveraddr));
serveraddr.sin_family=AF_INET;
serveraddr.sin_port=htons(4114);
inet_pton(AF_INET,argv[1],&serveraddr.sin_addr);
connect(sockfd,(struct sockaddr*)&serveraddr,sizeof(serveraddr));
recv(sockfd,recvbuff,sizeof(recvbuff),0);
printf("%s\n",recvbuff);
printf("please input the message:\n");
printf("please input the 'a' to add the module.\n");
printf("please input the 'c' close the WEB servers.\n");
printf("please input the 'o' open the WEB servers.\n");
printf("please input the 'f' filter the ICMP packet.\n");
printf("please input the 'i' accept the ICMP packet.\n");
printf("please input the 't' close the FTP servers.\n");
printf("please input the 'p' start the FTP servers.\n");
printf("please input the 'r' rmmod the all modules.\n");

scanf("%c",&w);


while(w!='q')
{
sebuff[0]=w;
send(sockfd,sebuff,1,0);
scanf("%c",&w);
switch(w)
{
case'a':
printf("start the module.\n");
break;

case'b':
printf("pause the connect.\n");
break;

case'c':
printf("start close the WEB server.\n");
break;

case'o':
printf("start open the WEB server.\n");
break;

case'f':
printf("start filter the ICMP packet.\n");
break;

case'i':
printf("start receive the ICMP packet.\n");
break;

case't':
printf("start close the FTP servers.\n");
break;

case'p':
printf("start open the FTP servers.\n");
break;

case'z':
printf("test.\n");
break;

case'r':
printf("rmmod the control modules.\n");
break;

default:
printf("------------------------.\n");


}


}
close(sockfd);
}

scutan

对于你声明的这些变量 如:
char sebuff[5];
char recvbuff[100];
在使用之前请将之清零,否则可能会产生难以预料的情况!

gaocheng

加MSG_DONTROUTE  flag 试试？