training_repo/non_blocking_client/client_non_blocking.c

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

#define SERVER_HOST "127.0.0.1"
#define SERVER_PORT 12345

int main()
{
    int sockfd;
    struct sockaddr_in server_addr;
    fd_set write_fds;
    struct timeval timeout;
    int flags, result;
    sockfd = socket(AF_INET, SOCK_STREAM, 0);
    if (sockfd == -1)
    {
        perror("socket");
        return 1;
    }
    memset(&server_addr, 0, sizeof(server_addr));
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(SERVER_PORT);
    if (inet_pton(AF_INET, SERVER_HOST, &server_addr.sin_addr) <= 0)
    {
        perror("inet_pton");
        close(sockfd);
        return 1;
    }
    flags = fcntl(sockfd, F_GETFL, 0);
    if (flags == -1)
    {
        perror("fcntl");
        close(sockfd);
        return 1;
    }
    if (fcntl(sockfd, F_SETFL, flags | O_NONBLOCK) == -1)
    {
        perror("fcntl");
        close(sockfd);
        return 1;
    }
    result = connect(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
    if (result < 0 && errno != EINPROGRESS)
    {
        perror("connect");
        close(sockfd);
        return 1;
    }
    printf("Trying to connect...\n");
    while (1)
    {
        FD_ZERO(&write_fds);
       // FD_SET(sockfd, &write_fds);
        timeout.tv_sec = 0;
        timeout.tv_usec = 100000;
        result = select(sockfd + 1, NULL, &write_fds, NULL, &timeout);
        if (result == -1)
        {
            perror("select");
            close(sockfd);
            return 1;
        }
        if (FD_ISSET(sockfd, &write_fds))
        {
            printf("Successfully connected to %s:%d\n", SERVER_HOST, SERVER_PORT);
            break;
        }
        else
        {
            printf("Still attempting to connect...\n");
            sleep(1);                                                                                                             }
    }
    close(sockfd);
    return 0;
}