opendir on ssh2 never stops

I need to fetch some files from the root directory of a distant server through ssh, the local machine uses php7. I've made this script:

<?php
$strServer = "my-server.com";
$strServerPort = "22";
$strServerUsername = "my.username";
$strServerPassword = "my-password";
$resConnection = ssh2_connect($strServer, $strServerPort);
if(ssh2_auth_password($resConnection, $strServerUsername, $strServerPassword)) {
    $files = array();
    $resSFTP = ssh2_sftp($resConnection);
    $dirHandle = opendir("ssh2.sftp://" . intval($resSFTP) . "/");
    while ($dirHandle && ($file = readdir($dirHandle)) !== false) {
        if ($file == "." || $file == "..") {
            continue;
        }
        $strData = file_get_contents("ssh2.sftp://" . intval($resSFTP) . "/" . $file);
        file_put_contents('/path/to/dir/' . $file, $strData);
    }
    ssh2_exec($resConnection, 'exit');
    unset($resConnection);
}

die;

It works, i.e. the files are fetched, but the script never stops.
If I knew the name of the file to fetch, the script would then be:

if(ssh2_auth_password($resConnection, $strServerUsername, $strServerPassword)) {
    $files = array();
    $resSFTP = ssh2_sftp($resConnection);
    $file = 'name_of_the_file.xlsx';
    $strData = file_get_contents("ssh2.sftp://" . intval($resSFTP) . "/" . $file);
    file_put_contents('/path/to/dir/' . $file, $strData);
}

and then the file is fetch and the script stops at the end of its execution.

I cannot use phpseclib as it requires composer and I can't use it on the locale machine.

What can I do to opendir() and readdir() without having the script running infinitely?

try to break after your file_put_contents

for example:

if (file_put_contents('/path/to/dir/' . $file, $strData) !== false) {
    break;
}

or as a best approach you may use closedir directly after putting your data

do {
    if ($file == "." || $file == "..") {
        continue;
    }
    $strData = file_get_contents("ssh2.sftp://" . intval($resSFTP) . "/" . $file);
    if (file_put_contents('/path/to/dir/' . $file, $strData)) {
        break;
    }
} while ($dirHandle && ($file = readdir($dirHandle)) !== false);

closedir($dirHandle);