检查连接是打开还是关闭？(在Linux中的C中)

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

int main() {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd < 0) {
        perror("socket creation failed");
        return 1;
    }

    struct sockaddr_in serv_addr;
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(8080);
    serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

    int conn_status = connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
    if (conn_status < 0) {
        perror("connection failed");
        return 1;
    }

    printf("Connection is open.\n");

    close(sockfd);
    return 0;
}

#include <curl/curl.h>
#include<stdio.h>

int main() {
    CURL *curl;
    CURLcode res;

    curl_global_init(CURL_GLOBAL_DEFAULT);
    curl = curl_easy_init();

    if (curl) {
        curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
        res = curl_easy_perform(curl);

        if (res == CURLE_OK) {
            printf("Connection is open.\n");
        } else {
            printf("Connection is closed.\n");
        }

        curl_easy_cleanup(curl);
    }

    curl_global_cleanup();
    return 0;
}