#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <net/if.h>
#include <errno.h>
#include "k.h"

K get_socket_interface(K handle) {
    // Check that the handle is of type int
    if (handle->t != -KI) {
        return krr("handle type");
    }

    int sock = handle->i;
    char if_name[IFNAMSIZ] = {0};
    socklen_t optlen = sizeof(if_name);

    // Get the network interface associated with the socket
    if (getsockopt(sock, SOL_SOCKET, SO_BINDTODEVICE, if_name, &optlen) == -1) {
        return krr(strerror(errno));
    }

    // Return the network interface name
    return kp(if_name);
}