prg6_9.c

Unix下用C语言进行网络编程的范例

// File: prg6_9.c
	#include <stdio.h>          /* These are the usual header files */ 
	#include <strings.h>          /* for bzero() */
	#include <unistd.h>         /* for close() */
	#include <sys/types.h> 
	#include <sys/socket.h> 
	#include <netinet/in.h> 
	#include <arpa/inet.h>
	#include <sys/time.h>
	#include <stdlib.h>

	#define PORT 1234   /* Port that will be opened */ 
	#define BACKLOG 5   /* Number of allowed connections */ 
	#define MAXDATASIZE 1000 
	typedef struct CLIENT{
	   int	 fd;
	   char*  name;
	   struct sockaddr_in addr; /* client's address information */
	   char* data;						
	};  
	void process_cli(CLIENT *client, char* recvbuf, int len);
	void savedata(char* recvbuf, int len, char* data);

	main() 
	{ 
	int	i, maxi, maxfd,sockfd;
	int	nready;
	ssize_t	n;
	fd_set	rset, allset;
	int listenfd, connectfd; /* socket descriptors */     
	struct sockaddr_in server; /* server's address information */ 
	/* client's information */ 
	CLIENT client[FD_SETSIZE];
	char recvbuf[MAXDATASIZE];
	int sin_size; 

	/* Create TCP socket  */
	if ((listenfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
	   /* handle exception */
	   perror("Creating socket failed.");
	   exit(1);
	   }

	int opt = SO_REUSEADDR;
	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) { 
	   /* handle exception */
	   perror("Bind error.");
	   exit(1); 
	   }    

	if(listen(listenfd,BACKLOG) == -1){  /* calls listen() */ 
	   perror("listen() error\n"); 
	   exit(1); 
	   } 

	sin_size=sizeof(struct sockaddr_in); 
	/*initialize for select */
	maxfd = listenfd;	
	maxi = -1;			
	for (i = 0; i < FD_SETSIZE; i++) {
	   client[i].fd = -1;	
	   }
	FD_ZERO(&allset);
	FD_SET(listenfd, &allset);

	while(1)
	{
	struct sockaddr_in addr;
	rset = allset;		
	nready = select(maxfd+1, &rset, NULL, NULL, NULL);

	if (FD_ISSET(listenfd, &rset)) {	/* new client connection */
	   /* Accept connection */
	   if ((connectfd = accept(listenfd,(struct sockaddr *)&addr,&sin_size))==-1) {
	      perror("accept() error\n"); 
	      continue; 
	      }
	   /* Put new fd to client */
	   for (i = 0; i < FD_SETSIZE; i++)
	      if (client[i].fd < 0) {
	         client[i].fd = connectfd;	/* save descriptor */
	         client[i].name = new char[MAXDATASIZE];
	         client[i].addr = addr;
	         client[i].data = new char[MAXDATASIZE];
	         client[i].name[0] = '\0';
	         client[i].data[0] = '\0';
	         printf("You got a connection from %s.  ",inet_ntoa(client[i].addr.sin_addr) ); 
	         break;
	         }
	      if (i == FD_SETSIZE)	    printf("too many clients\n");
	      FD_SET(connectfd, &allset);	/* add new descriptor to set */
	      if (connectfd > maxfd)  maxfd = connectfd;	
	      if (i > maxi)	maxi = i;		
	      if (--nready <= 0) continue;	/* no more readable descriptors */
	      }

	   for (i = 0; i <= maxi; i++) {	/* check all clients for data */
	      if ( (sockfd = client[i].fd) < 0)	continue;
	      if (FD_ISSET(sockfd, &rset)) {
	         if ( (n = recv(sockfd, recvbuf, MAXDATASIZE,0)) == 0) {
	            /*connection closed by client */
	            close(sockfd);
	            printf("Client( %s ) closed connection. User's data: %s\n",client[i].name,client[i].data);
	            FD_CLR(sockfd, &allset);
	            client[i].fd = -1;
	            delete client[i].name;
	            delete client[i].data;
	            } else
	            process_cli(&client[i], recvbuf, n);
	         if (--nready <= 0)	break;	/* no more readable descriptors */
	         }
	   }
	}
	close(listenfd);   /* close listenfd */         
	} 

	void process_cli(CLIENT *client, char* recvbuf, int len)
	{
	char sendbuf[MAXDATASIZE];

	recvbuf[len-1] = '\0';
	if (strlen(client->name) == 0) {
	   /* Got client's name from client */
	   memcpy(client->name,recvbuf, len);
	   printf("Client's name is %s.\n",client->name);
	   return;
	   }

	/* save client's data */
	printf("Received client( %s ) message: %s\n",client->name, recvbuf);
	/* save user's data */
	savedata(recvbuf,len, client->data);
	/* reverse usr's data */
	for (int i1 = 0; i1 < len - 1; i1++) {
	   sendbuf[i1] = recvbuf[len - i1 -2];
	}
	sendbuf[len - 1] = '\0';

	send(client->fd,sendbuf,strlen(sendbuf),0); 
	}

	void savedata(char* recvbuf, int len, char* data)
	{
	int start = strlen(data);
	for (int i = 0; i < len; i++) {
	   data[start + i] = recvbuf[i];
	}         
	}