Linux 网络编程（多路复用）

• 服务器端代码

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<unistd.h>
#include<netinet/in.h>
#include <errno.h>
#include <sys/fcntl.h>
 
typedef struct _CLIENT{
    int fd;
    struct sockaddr_in addr;
    char recvbuf[];
}CLIENT_S;
 
int main(int argc, char** argv){
 
    int socketfd,new_fd;
    CLIENT_S sock_list[];
    struct sockaddr_in server_addr;
    struct sockaddr_in client_addr;
    struct timeval tv;
    char recvbuf[];
    int res;
    int max;
    int len,nbytes;
    int port = ;
    int i;
 
    for(i = ; i < ; i ++){
        sock_list[i].fd = -;
    }
 
    if((socketfd = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) == ){
        fprintf(stderr, "socket Error:%s\n\a", strerror(errno));
        exit();
    }
 
    //设置为非阻塞
    if (fcntl(socketfd, F_SETFL, O_NONBLOCK) == -) {
        fprintf(stderr, "fcntl Error:%s\n\a", strerror(errno));
        exit();
    }
 
    bzero(&server_addr, sizeof(struct sockaddr_in));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    server_addr.sin_addr.s_addr =  htonl(INADDR_ANY);
 
    if((bind(socketfd, &server_addr, sizeof(server_addr))) == -){
        fprintf(stderr, "bind Error:%s\n\a", strerror(errno));
        exit();
    }
 
    if(listen(socketfd, ) == -){
        fprintf(stderr, "listen Error:%s\n\a", strerror(errno));
        exit();
    }
 
    sock_list[].fd = socketfd;
    max = socketfd;
    fd_set watchset;//select所需要的文件描述符
    FD_ZERO(&watchset);
    //将监听socket放入扫描集合
    FD_SET(socketfd, &watchset);
 
    while(){
            FD_ZERO(&watchset); 
 
            FD_SET(socketfd, &watchset);
            for(i = ; i < ; i ++){
                if (sock_list[i].fd != -) {
                    FD_SET(sock_list[i].fd, &watchset);
                }
            }
 
            res = select(max + , &watchset, NULL, NULL, NULL);
 
            if(- == res){
                fprintf(stderr, "select Error:%s\n\a", strerror(errno));
                exit();
            }else if( == res){
                printf("Select() break and the return num is");
                continue;
            }else{
                if(FD_ISSET(socketfd, &watchset)){
                    len = sizeof(struct sockaddr_in);
                    if ((new_fd = accept(socketfd,
                        (struct sockaddr *)&client_addr,
                        &len)) == -) {
                        fprintf(stderr, "Accept error:%s\n\a", strerror(errno));
                        exit();
                    }
 
                    for(i = ; i < ; i ++){
                        if (sock_list[i].fd == -) {
                            sock_list[i].fd = new_fd;
                            sock_list[i].addr = client_addr;
                            break;
                         }
                    }
 
                    fprintf(stderr, "new connect: %d\n", sock_list[i].fd);  
 
                    //将其放入socket的监听集合
                    FD_SET(new_fd, &watchset);
                    if (max < new_fd) {
                        max = new_fd;
                    }  
 
                    continue;
                }else{
                    for (i  = ; i < ; i++) { //data
                        if (sock_list[i].fd == -)
                            continue;
                        if (!FD_ISSET(sock_list[i].fd, &watchset)) {
                            continue;
                        }
 
                        nbytes = recv(sock_list[i].fd, sock_list[i].recvbuf, sizeof(sock_list[i].recvbuf), );
                        recvbuf[nbytes] = '\0';
 
                        printf("recv data is:%s\n",sock_list[i].recvbuf); 
 
                        break;
                    }
                }
            }
    }//while(1)
 
    exit();
}