chats.c

linux下用c写的简易聊天室程序

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <sys/select.h>

#define MAXLINE 1024
#define BACKLOG 20
int
main(int argc, char **argv)
{
	int		 i, j,maxi, maxfd, listenfd, connfd, sockfd;
	int			nready, client[FD_SETSIZE];
	ssize_t			n;
	fd_set			rset, allset;
	char			line[MAXLINE],temp[INET_ADDRSTRLEN];
	socklen_t		clilen,templen;
	struct sockaddr_in	cliaddr, servaddr,tempaddr;

	if ( (listenfd = socket(AF_INET, SOCK_STREAM, 0))<0 ) 
	  {
	    perror("socket");
	  }

       bzero(&servaddr,sizeof(servaddr));
       servaddr.sin_family = AF_INET;
       servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
       servaddr.sin_port = 0;

       if (bind(listenfd,(struct sockaddr *)&servaddr,sizeof(servaddr)) == -1)
       {
         perror("bind");
         exit(1);
        }
    /* how we can get the binded socket information */
       templen = sizeof(struct sockaddr);
      if (getsockname(listenfd, (struct sockaddr *)&tempaddr,&templen) == -1){
      perror("getsockname");
      exit(1);
      }
      printf("Server is listening on port %d\n",ntohs(tempaddr.sin_port));
       if (listen(listenfd,BACKLOG) == -1){
         perror("listen");
         exit(1);
       }


	maxfd = listenfd;			/* initialize */
	maxi = -1;				/* index into client[] array */
	for (i = 0; i < FD_SETSIZE; i++)
		client[i] = -1;			/* -1 indicates available entry */
	FD_ZERO(&allset);
	FD_SET(listenfd, &allset);

	for ( ; ; ) {
		rset = allset;		/* structure assignment */
		nready = select(maxfd+1, &rset, NULL, NULL, NULL);

		if (FD_ISSET(listenfd, &rset)) {	/* new client connection */
			clilen = sizeof(cliaddr);
			if ( (	connfd = accept(listenfd, (struct sockaddr *) &cliaddr, &clilen) ) <  0)
			{
			  perror("accept");
			}
			printf("A new guy from: %s, port %d\n",
					inet_ntop(AF_INET, &cliaddr.sin_addr, temp, INET_ADDRSTRLEN),
					ntohs(cliaddr.sin_port));

			for (i = 0; i < FD_SETSIZE; i++)
				if (client[i] < 0) {
					client[i] = connfd;	/* save descriptor */
					break;
				}
			if (i == FD_SETSIZE)
				perror("too many clients");

			FD_SET(connfd, &allset);	/* add new descriptor to set */
			if (connfd > maxfd)
				maxfd = connfd;			/* for select */
			if (i > maxi)
				maxi = i;				/* max index in client[] array */

			if (--nready <= 0)
				continue;				/* no more readable descriptors */
		}

		for (i = 0; i <= maxi; i++) {	/* check all clients for data */
			if ( (sockfd = client[i]) < 0)
				continue;
			if (FD_ISSET(sockfd, &rset)) {
				if ( (n = read(sockfd, line, MAXLINE)) == 0) {
						/*4connection closed by client */
					close(sockfd);
					FD_CLR(sockfd, &allset);
					client[i] = -1;
				} else
				  {
				    printf("%s",line);
                      for(j=0;(j<=maxi)&&((sockfd=client[j])>=0);j++)
                        {  if(j==i)
                             continue;
                           write(sockfd,line,n);
                         } 
				  }

				if (--nready <= 0)
					break;				/* no more readable descriptors */
			}
		}
	}
}