UDP服务recvfrom函数设置非阻塞

比眉伴天荒 2022-06-16 23:56 640阅读 0赞

**基本概念：**

其实UDP的非阻塞也可以理解成和TCP是一样的，都是通过socket的属性去做。

方法一：通过**fcntl函数**将套接字设置为非阻塞模式**。**

方法二：通过**套接字选项SO\_RECVTIMEO**设置超时。

**方法一源码**，编译：**g++ udp\_server.cpp -o server**

#include <stdio.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <errno.h>
    #include <strings.h>
    #include <stdlib.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <fcntl.h>
    #include <unistd.h>
    
    void Perror(const char *s)
    {
        perror(s);
        exit(EXIT_FAILURE);
    }
    
    //设置非阻塞
    static void setnonblocking(int sockfd) {
        int flag = fcntl(sockfd, F_GETFL, 0);
        if (flag < 0) {
            Perror("fcntl F_GETFL fail");
            return;
        }
        if (fcntl(sockfd, F_SETFL, flag | O_NONBLOCK) < 0) {
            Perror("fcntl F_SETFL fail");
        }
    }
    
    int main()
    {
        int sockfd;
        int port = 9527;
        struct sockaddr_in servaddr, cliaddr;
    
        sockfd = socket(AF_INET, SOCK_DGRAM, 0);
        if (sockfd == -1) {
            Perror("socket failed:");
        }
        setnonblocking(sockfd);
    
        bzero(&servaddr, sizeof(servaddr));
        servaddr.sin_family = AF_INET;
        servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
        servaddr.sin_port = htons(port);
    
        if (bind(sockfd, (sockaddr *)&servaddr, sizeof(servaddr)) == -1) {
            Perror("bind failed:");
        }
    
        socklen_t len;
        for ( ; ; ) {
            char mesg[1024] = {};
            int n = recvfrom(sockfd, mesg, 1024, 0, (sockaddr *)&cliaddr, &len);
            sleep(1);
            perror("recvfrom fail: ");
        }
    
        return 0;
    }

**方法二源码**，编译：**g++ udp\_server.cpp -o server**

#include <stdio.h>
    #include <sys/types.h>
    #include <sys/socket.h>
    #include <errno.h>
    #include <strings.h>
    #include <stdlib.h>
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <fcntl.h>
    #include <unistd.h>
    #include <sys/time.h>
    
    void Perror(const char *s)
    {
        perror(s);
        exit(EXIT_FAILURE);
    }
    
    int main()
    {
        int sockfd;
        int port = 9527;
        struct sockaddr_in servaddr, cliaddr;
    
        sockfd = socket(AF_INET, SOCK_DGRAM, 0);
        if (sockfd == -1) {
            Perror("socket failed:");
        }
    
        // 设置超时
        struct timeval timeout;
        timeout.tv_sec = 1;//秒
        timeout.tv_usec = 0;//微秒
        if (setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, &timeout, sizeof(timeout)) == -1) {
            Perror("setsockopt failed:");
        }
    
        bzero(&servaddr, sizeof(servaddr));
        servaddr.sin_family = AF_INET;
        servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");
        servaddr.sin_port = htons(port);
    
        if (bind(sockfd, (sockaddr *)&servaddr, sizeof(servaddr)) == -1) {
            Perror("bind failed:");
        }
        
        socklen_t len;
        for ( ; ; ) {
            char mesg[1024] = {};
            int n = recvfrom(sockfd, mesg, 1024, 0, (sockaddr *)&cliaddr, &len);
            perror("recvfrom fail: ");
    
        }
    
        return 0;
    }

原文出自：[http://blog.csdn.net/daiyudong2020/article/details/70039409][http_blog.csdn.net_daiyudong2020_article_details_70039409]

End;

[http_blog.csdn.net_daiyudong2020_article_details_70039409]: http://blog.csdn.net/daiyudong2020/article/details/70039409