linux udp 超时

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/time.h>

#define SERVER "127.0.0.1"
#define BUFLEN 512
#define PORT 8888
#define TIMEOUT_SEC 5

int main(void)
{
    struct sockaddr_in si_other;
    int sockfd, slen = sizeof(si_other);
    char buf[BUFLEN];
    struct timeval tv;

    if ((sockfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)) == -1)
    {
        perror("socket");
        exit(1);
    }

    memset((char *) &si_other, 0, sizeof(si_other));
    si_other.sin_family = AF_INET;
    si_other.sin_port = htons(PORT);
    if (inet_aton(SERVER, &si_other.sin_addr) == 0)
    {
        fprintf(stderr, "inet_aton() failed\n");
        exit(1);
    }

    // 设置超时
    tv.tv_sec = TIMEOUT_SEC;
    tv.tv_usec = 0;
    setsockopt(sockfd, SOL_SOCKET, SO_RCVTIMEO, (const char*)&tv, sizeof tv);

    if (sendto(sockfd, "Hello", strlen("Hello"), 0, &si_other, slen) == -1)
    {
        perror("sendto()");
        exit(1);
    }

    int n = recvfrom(sockfd, buf, BUFLEN, 0, &si_other, &slen);
    if (n == -1)
    {
        if (errno == EWOULDBLOCK || errno == EAGAIN)
        {
            printf("Timeout occurred! No data after %d seconds.\n", TIMEOUT_SEC);
        }
        else
        {
            perror("recvfrom()");
        }
    }
    else
    {
        printf("Received packet from %s:%d\n", inet_ntoa(si_other.sin_addr), ntohs(si_other.sin_port));
        printf("Data: %s\n", buf);
    }

    close(sockfd);
    return 0;
}