server.c

linux下一个CS通信模型

#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define PORT 2345
#define BACKLOG 5
#define MAXDATASIZE 100
int main(void)
{
 int listenfd, connectfd,numberb;
 struct sockaddr_in server, client;
 int sin_size,i;
 char buf1[MAXDATASIZE];
 char buf2[MAXDATASIZE];
 int opt = SO_REUSEADDR;
 if((listenfd=socket(AF_INET,SOCK_STREAM,0))==-1)
 {
   perror("Create socket failed.");
   exit(-1);
 }
 setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
 bzero(&server, sizeof(server));
 server.sin_family = AF_INET;
 server.sin_port = htons(PORT);
 server.sin_addr.s_addr = htonl(INADDR_ANY);
 if (bind(listenfd, (struct sockaddr *)&server, sizeof(struct sockaddr))==-1)
 {
  perror("Bind error.");
  exit(-1);
 }
 if (listen(listenfd, BACKLOG) == -1)
 {
  perror("Listen error.");
  exit(-1);
 }
 sin_size = sizeof(struct sockaddr_in);
 while(1)
 {
  if ((connectfd = accept(listenfd, (struct sockaddr *)&client, &sin_size)) == -1)
  {
   perror("accept error.");
   exit(-1);
  }
  printf("You get a connection from %s\n", inet_ntoa(client.sin_addr));
  if((numberb=recv(connectfd, buf1, MAXDATASIZE, 0)) != -1) 
  {
    buf1[numberb]='\0';
   printf("Client Message: %s\n",buf1);
   if((strcmp(buf1,"quit"))!=0)
     {
       for(i=0;i<=numberb;i++)
       {
        buf2[i]=buf1[numberb-i-1];
       }
       buf2[numberb]='\0';
       send(connectfd,buf2,numberb,0);
	 }
   else
     {
      
       send(connectfd,"goodbye",7,0);
       perror("revc error.");
       exit(1);
     }
  }
  
 close(connectfd);
 } /* while */
 close(listenfd);
 return 0;
}