Method for PHP to get windows login user name

A few days ago, I asked this question in the Q&A area. All the friends who answered the question said that it was impossible to realize it through PHP. It happened that my internship leader helped me find a method, which seemed to be realized through NTLM. I am a novice, and I don't know the specific principle. I just tested it myself and it is very easy to use.
This is written by a Frenchman, so the annotations in the code are all in French. If there are friends who want to know the meaning of the annotations in a certain line, please reply and explain it. I can try to translate it.

<?php
/***********************************************************************
************************************************************************
*
* PHP NTLM GET LOGIN 
* Version 0.2.1                  
* Copyright (c) 2004 Nicolas GOLLET ( Nicolas (dot) gollet (at) secusquad (dot) com )
* Copyright (c) 2004 Flextronics Saint-Etienne
*
* This program is free software. You can redistribute it and/or modify 
* it under the terms of the GNU General Public License as published by 
* the Free Software Foundation; either version 2 of the License.    
*
***********************************************************************/
session_start();
$headers = apache_request_headers(); //  Get user header 
if (@$_SERVER['HTTP_VIA'] != NULL){ //  Verify that the proxy is used (proxy), Because ntlm Authentication cannot pass through proxy .
echo "Proxy bypass!";
}
elseif($headers['Authorization'] == NULL){  //si l'entete autorisation est inexistante If the permission header does not exist 
 header( "HTTP/1.0 401 Unauthorized" );  //envoi au client le mode d'identification
 header( "WWW-Authenticate: NTLM" );  //dans notre cas le NTLM
 exit;    //on quitte
}
if(isset($headers['Authorization']))   //dans le cas d'une authorisation (identification)
{ 
 if(substr($headers['Authorization'],0,5) == 'NTLM '){ //  Confirm client Whether it is in ntlm Under 

  $chaine=$headers['Authorization'];   
  $chaine=substr($chaine, 5);  //  Get  base64-encoded type1  Information 
  $chained64=base64_decode($chaine); //  Decoding  base64  To  $chained64
  
  if(ord($chained64{8}) == 1){   
  //   |_ byte signifiant l'etape du processus d'identification (etape 3) 
 
  // verification du drapeau NTLM "0xb2" ?l'offset 13 dans le message type-1-message (comp ie 5.5+) :
  if (ord($chained64[13]) != 178){
   echo "NTLM Flag error!";
   exit;
  }

  $retAuth = "NTLMSSP".chr(000).chr(002).chr(000).chr(000).chr(000).chr(000).chr(000).chr(000);
  $retAuth .= chr(000).chr(040).chr(000).chr(000).chr(000).chr(001).chr(130).chr(000).chr(000);
  $retAuth .= chr(000).chr(002).chr(002).chr(002).chr(000).chr(000).chr(000).chr(000).chr(000);
  $retAuth .= chr(000).chr(000).chr(000).chr(000).chr(000).chr(000).chr(000);
  
  $retAuth64 =base64_encode($retAuth); // encode en base64
  $retAuth64 = trim($retAuth64);  // enleve les espaces de debut et de fin
  header( "HTTP/1.0 401 Unauthorized" );  // envoi le nouveau header
  header( "WWW-Authenticate: NTLM $retAuth64" ); // avec l'identification suppl In fact, in fact, the entaire
  exit;
  
  }
  
  else if(ord($chained64{8}) == 3){
  //     |_ byte signifiant l'etape du processus d'identification (etape 5)

  // on recupere le domaine
  $lenght_domain = (ord($chained64[31])*256 + ord($chained64[30])); // longueur du domain
  $offset_domain = (ord($chained64[33])*256 + ord($chained64[32])); // position du domain. 
  $domain = str_replace("\0","",substr($chained64, $offset_domain, $lenght_domain)); // decoupage du du domain
  
  //le login
  $lenght_login = (ord($chained64[39])*256 + ord($chained64[38])); // longueur du login.
  $offset_login = (ord($chained64[41])*256 + ord($chained64[40])); // position du login.
  $login = str_replace("\0","",substr($chained64, $offset_login, $lenght_login)); // decoupage du login
  
  if ( $login != NULL){
   // stockage des donn In fact, in fact, the s dans des variable de session
   $_SESSION['Login']=$login;
   header("Location: newpage.php");
   exit;
  }
  else{
   echo "NT Login empty!";
  }
   
 
  }
 }
}
?>