Linux下网络编程-Select实现I/O复用的简易服务器和客户端

Linux下网络编程-Select实现I/O复用的简易服务器和客户端

Select实现I/O复用的简易服务器:

// Select实现I/O复用服务端
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/select.h>

#define BUF_SIZE 100
void error_handling(const char *message);

int main(int argc, char *argv[])
{
    if(argc!=2) 
    {
		printf("Usage : %s <port>\n", argv[0]);
		exit(1);
	}

    int serv_sock, clnt_sock;
	struct sockaddr_in serv_adr, clnt_adr;
    struct timeval timeout;
    fd_set reads,cpy_reads;

    socklen_t adr_sz;
    int fd_max,str_len,fd_num,i;
    char buf[BUF_SIZE];

    serv_sock=socket(PF_INET, SOCK_STREAM, 0);
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family=AF_INET;
	serv_adr.sin_addr.s_addr=htonl(INADDR_ANY);
	serv_adr.sin_port=htons(atoi(argv[1]));
	
	if(bind(serv_sock, (struct sockaddr*) &serv_adr, sizeof(serv_adr))==-1)
		error_handling("bind() error");
	if(listen(serv_sock, 5)==-1)
		error_handling("listen() error");   
    
    FD_ZERO(&reads);//将reads所有位初始化为0
    FD_SET(serv_sock,&reads);//向reads中注册serv_sock的信息
    fd_max=serv_sock;

    while(1)
    {
        cpy_reads=reads;
        timeout.tv_sec=5;
        timeout.tv_usec=5000;

        if((fd_num=select(fd_max+1,&cpy_reads,0,0,&timeout))==-1) break;

        if(fd_num==0)   continue;

        for(int i=0;i<fd_max+1;i++)
        {
            if(FD_ISSET(i,&cpy_reads))
            {
                if(i==serv_sock)//连接请求
                {
                    adr_sz=sizeof(clnt_adr);
                    clnt_sock=accept(serv_sock,(struct sockaddr*)&clnt_adr,&adr_sz);
                    FD_SET(clnt_sock,&reads);
                    if(fd_max<clnt_sock)
                    {
                        fd_max=clnt_sock;
                    }
                    printf("connected client:%d\n",clnt_sock);
                }
                else//读消息
                {
                    str_len=read(i,buf,BUF_SIZE);
                    if(str_len==0)
                    {
                        FD_CLR(i,&reads);
                        close(i);
                        printf("closed client:%d\n",i);
                    }
                    else
                    {
                        write(i,buf,str_len);
                    }
                }
            }
        }
    }

    close(serv_sock);
    return 0;
}

void error_handling(const char *message)
{
    fputs(message, stderr);
	fputc('\n', stderr);
	exit(1);
}

客户端:

// Select实现I/O复用客户端
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#define BUF_SIZE 1024
void error_handling(const char *message);

int main(int argc, char *argv[])
{
    if(argc!=3) 
    {
		printf("Usage : %s <IP> <port>\n", argv[0]);
		exit(1);
	}

    int sock;
	char message[BUF_SIZE];
	int str_len;
	struct sockaddr_in serv_adr;

    sock=socket(PF_INET, SOCK_STREAM, 0);   
	if(sock==-1)
		error_handling("socket() error");
	
	memset(&serv_adr, 0, sizeof(serv_adr));
	serv_adr.sin_family=AF_INET;
	serv_adr.sin_addr.s_addr=inet_addr(argv[1]);
	serv_adr.sin_port=htons(atoi(argv[2]));
	
	if(connect(sock, (struct sockaddr*)&serv_adr, sizeof(serv_adr))==-1)
		error_handling("connect() error!");
	else
		puts("Connected...........");


    while(1)
    {
        fputs("Input message(Q to quit): ", stdout);
		fgets(message, BUF_SIZE, stdin);
		
		if(!strcmp(message,"q\n") || !strcmp(message,"Q\n"))
			break;

		write(sock, message, strlen(message));
		str_len=read(sock, message, BUF_SIZE-1);
		message[str_len]=0;
		printf("Message from server: %s", message);
    }

    close(sock);
    return 0;
}

void error_handling(const char *message)
{
    fputs(message, stderr);
	fputc('\n', stderr);
	exit(1);
}