Linux网络编程基础（三） IO非阻塞操作

IO非阻塞操作

          sock的方法不一定非得是阻塞的，也可以非阻塞的操作。有两种方法分别为设置fcntl 和设置相应函数的参数。

 

    服务端：

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

#define  BUFSIZE 128

int main(int argc,char *argv[]){
    int server_sockfd, client_sockfd;
    int server_len, client_len;
    struct sockaddr_in server_address;
    struct sockaddr_in client_address;
    int i,byte;
    char char_send[BUFSIZE];

    server_sockfd = socket(AF_INET, SOCK_STREAM, 0);

    bzero(&server_address, sizeof(server_address));
    server_address.sin_family = AF_INET;
    server_address.sin_port = htons(7838);
    server_address.sin_addr.s_addr = INADDR_ANY;
    server_len = sizeof(server_address);

    if ((bind(server_sockfd, (struct sockaddr *)&server_address, server_len))== -1) {
        perror("bind");
        exit(EXIT_FAILURE);
    }

    listen(server_sockfd, 5);

    printf("server waiting for connect\n");

    client_len = sizeof(client_address);
    client_sockfd = accept(server_sockfd,(struct sockaddr *)&client_address, (socklen_t *)&client_len);

    for(i=0;i<5;i++){
        memset(char_send,'\0',BUFSIZE);
        printf("input message to send:");
        fgets(char_send,BUFSIZE,stdin);
        if((byte=send(client_sockfd,char_send,strlen(char_send),0))==-1){
            perror("send");
            exit(EXIT_FAILURE);
        }

        memset(char_send,'\0',BUFSIZE);
        //最后一个参数为非阻塞的设置
        byte = recv(client_sockfd, char_send, BUFSIZE,MSG_DONTWAIT);
        if(byte > 0){
            printf("get %d message:%s", byte, char_send);
            byte=0;
        }else if(byte<0){
            if(errno==EAGAIN){
                errno=0;
                continue;
            }else{
                perror("recv");
                exit(EXIT_FAILURE);
            }
        }
    }
    shutdown(client_sockfd,2);
    shutdown(server_sockfd,2);
}

        客户端：

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

#define MAXBUF 128

int main(int argc, char **argv){
    int sockfd, ret, i;
    struct sockaddr_in dest, mine;
    char buffer[MAXBUF + 1];

    if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
        perror("Socket");
        exit(EXIT_FAILURE);
    }

    bzero(&dest, sizeof(dest));
    dest.sin_family = AF_INET;
    dest.sin_port = htons(7838);
    if(argc<2){
        printf("Usage: %s <dest ip> <src ip>",argv[0]);
        exit(1);
    }
    if (inet_aton(argv[1], (struct in_addr *) &dest.sin_addr.s_addr) == 0){
        perror(argv[1]);
        exit(1);
    }

    bzero(&mine, sizeof(mine));
    mine.sin_family = AF_INET;
    mine.sin_port = htons(7839);
    if (inet_aton(argv[2], (struct in_addr *) &mine.sin_addr.s_addr) == 0){
        perror(argv[2]);
        exit(EXIT_FAILURE);
    }
    if (bind(sockfd, (struct sockaddr *) &mine, sizeof(struct sockaddr)) == -1){
        perror(argv[3]);
        exit(EXIT_FAILURE);
    }
    printf("will connect!\n");
    if (connect(sockfd, (struct sockaddr *) &dest, sizeof(dest)) != 0) {
        perror("Connect ");
        exit(EXIT_FAILURE);
    }
    //设置sock连接的非阻塞
    if(fcntl(sockfd, F_SETFL, O_NONBLOCK) == -1) {
        perror("fcntl");
        exit(EXIT_FAILURE);
    }

    while(1){
        bzero(buffer, MAXBUF + 1);
        //因为在socket中设置过，所以就不用再设置了
        ret = recv(sockfd, buffer, MAXBUF, 0);
        if(ret > 0){
            printf("get %d message:%s", ret, buffer);
            ret=0;
        }else if(ret < 0) {
            if(errno == EAGAIN) {
                errno=0;
                continue;
            }else{
                perror("recv");
                exit(EXIT_FAILURE);
            }
        }

        memset( buffer,'\0',MAXBUF+1);
        printf("input message to send:");
        fgets( buffer,MAXBUF,stdin);
        if((ret=send(sockfd,buffer,strlen(buffer),0))==-1){
            perror("send");
            exit(EXIT_FAILURE);
        }

    }
    close(sockfd);
    return 0;
}