// 简化的连接示例
int connect_ftp(const char* host, int port) {
    int sockfd = socket(AF_INET, SOCK_STREAM, 0);
    struct sockaddr_in server_addr;
    server_addr.sin_family = AF_INET;
    server_addr.sin_port = htons(port);
    inet_pton(AF_INET, host, &server_addr.sin_addr);
    connect(sockfd, (struct sockaddr*)&server_addr, sizeof(server_addr));
    return sockfd;
}