tcpser.c

该程序包详细讲述了Linux环境下的Socket编程

#include<sys/types.h>
#include<sys/socket.h>
#include<netinet/in.h>
#include<arpa/inet.h>
#include<unistd.h>
#define PORT 5678
#define MAX 10
main()
{
   int sockfd,newsockfd,is_connected[MAX],fd;
   struct sockaddr_in addr;
   int addr_len = sizeof(struct sockaddr_in);
   fd_set myreadfds;
   char msgbuffer[256];
   char msg[] ="This is the message from server.Connected.\n";
   
   if ((sockfd = socket(AF_INET,SOCK_STREAM,0))<0)
   {
      perror("socket");
      exit(1);
   }
   else
   {
      printf("socket created .\n");
      printf("socked id: %d \n",sockfd);
   }
   
   bzero(&addr,sizeof(addr));
   addr.sin_family =AF_INET;
   addr.sin_port = htons(PORT);
   addr.sin_addr.s_addr = htonl(INADDR_ANY);
  
   if(bind(sockfd,&addr,sizeof(addr))<0)
   {
      perror("connect");
      exit(1);
   }
   else
   {
       printf("connected.\n");
       printf("local port:%d\n",PORT)	;
   }

   if(listen(sockfd,3)<0)
   {
      perror("listen");
      exit(1);
   }
   else
   {
      printf("listenning......\n");	
   }

   for(fd=0;fd<MAX;fd++)
   {
      is_connected[fd]=0;/*设置所有*/
   }
   
   while(1)
   {
      FD_ZERO(&myreadfds);
      FD_SET(sockfd,&myreadfds);
      for(fd=0;fd<MAX;fd++)
      {
         if(is_connected[fd])
         {
         	 FD_SET(fd,&myreadfds);
	     }
      }
      if(!select(MAX,&myreadfds,NULL,NULL,NULL))
      {
      	  continue;
      }
      for(fd=0;fd<MAX;fd++)
      {            
         if(FD_ISSET(fd,&myreadfds))
         {
            if(sockfd==fd)
            {
               if((newsockfd = accept (sockfd,&addr,&addr_len))<0)
               {
                  perror("accept");
	           }
               write(newsockfd,msg,sizeof(msg));
               is_connected[newsockfd] =1;
               printf("cnnect from %s\n",inet_ntoa(addr.sin_addr));
            }
            else
            {       	
               bzero(msgbuffer,sizeof(msgbuffer));
               if(read(fd,msgbuffer,sizeof(msgbuffer))<=0)
               {
                  printf("connect closed.\n");
                  is_connected[fd]=0;
                  close(fd);
                }
                else
                {
                   write(fd,msgbuffer,sizeof(msgbuffer));
                   printf("message:%s \n",msgbuffer);
	            }
             }
         }
      }
   }
}