server.c

提供了非阻塞的客户端和服务器端通信的实例程序。用linux下的C语言实现。

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/time.h>
#include <sys/types.h>

#define MAXBUF 1024

typedef struct CLIENT {
	int fd;
	struct sockaddr_in addr;	
}CLIENT;

/***************************
**server for multi-client 
**PF_SETSIZE=1024
****************************/
int main(int argc, char** argv)
{
	int i,n,maxi = -1;
	int nready;
	int slisten,sockfd,maxfd=-1,connectfd;
	
	unsigned int myport,lisnum; 

	struct sockaddr_in  my_addr,addr;
	struct timeval tv;
	
	socklen_t len;
	fd_set rset,allset;	
	
	char buf[MAXBUF + 1];
	CLIENT client[FD_SETSIZE];

	if(argv[1]) 
		myport = atoi(argv[1]);
	else
		myport = 1234;

	if(argv[2])
		lisnum = atoi(argv[2]);
	else 
		lisnum = FD_SETSIZE;

	if((slisten = socket(AF_INET,SOCK_STREAM,0)) == -1)
	{
		perror("socket");
		exit(1);
	}

	bzero(&my_addr,sizeof(my_addr));
	my_addr.sin_family = AF_INET;
	my_addr.sin_port = htons(myport);
	my_addr.sin_addr.s_addr = INADDR_ANY;

	if(bind(slisten, (struct sockaddr *)&my_addr, sizeof(my_addr)) == -1) {
        	perror("bind");
        	exit(1);
        }

	if (listen(slisten, lisnum) == -1) {
        	perror("listen");
        	exit(1);
    	}

	for(i=0;i<FD_SETSIZE;i++)
	{
		client[i].fd = -1;
	}

	FD_ZERO(&allset);           
        FD_SET(slisten, &allset);  
	maxfd = slisten;
	
	printf("Waiting for connections and data...\n");
	while (1)
	{		
		rset = allset;        	

		tv.tv_sec = 1;
       		tv.tv_usec = 0;
          
       		nready = select(maxfd + 1, &rset, NULL, NULL, &tv);

		if(nready == 0)
			continue;
		else if(nready < 0)
		{
			printf("select failed!\n");
			break;
		}	
		else 
		{
			if(FD_ISSET(slisten,&rset)) // new connection
			{			
				len = sizeof(struct sockaddr);
				if((connectfd = accept(slisten,
					(struct sockaddr*)&addr,&len)) == -1)
				{
					perror("accept() error\n");
					continue;
				}
				for(i=0;i<FD_SETSIZE;i++)
				{
					if(client[i].fd < 0)
					{
						client[i].fd = connectfd;
						client[i].addr = addr; 				
						printf("Yout got a connection from %s.\n",
						inet_ntoa(client[i].addr.sin_addr));
						break;
					}
				}
				if(i == FD_SETSIZE)			
					printf("too many connections");			
				FD_SET(connectfd,&allset);
				if(connectfd > maxfd)
					maxfd = connectfd;
				if(i > maxi)
					maxi = i;
			}
			else
			{			
				for(i=0;i<=maxi;i++)
				{			
					if((sockfd = client[i].fd)<0)
						continue;				
					if(FD_ISSET(sockfd,&rset))
					{						
						bzero(buf,MAXBUF + 1);
						if((n = recv(sockfd,buf,MAXBUF,0)) > 0)
						{
	printf("received data:%s\n from %s\n",buf,inet_ntoa(client[i].addr.sin_addr));	
						}				
						else
						{
						    printf("disconnected by client!\n");
							close(sockfd);
							FD_CLR(sockfd,&allset);
							client[i].fd = -1;
						}
					}
				}
			}
		}	
	}
	close(slisten);
}