gpstools/auth.php

<?php

if (!isset($status))
 die('Direct access not allowed.');

include_once("config.php");

$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) 
 die("Connection failed: " . $conn->connect_error);

$realm = 'GPS Tracker';

if (empty($_SERVER['PHP_AUTH_DIGEST'])) {
 header('HTTP/1.1 401 Unauthorized');
 header('WWW-Authenticate: Digest realm="'.$realm.
        '",qop="auth",nonce="'.uniqid().'",opaque="'.md5($realm).'"');

 die('Authentication failed.');
}

if (!($data = http_digest_parse($_SERVER['PHP_AUTH_DIGEST']))) {
 header('HTTP/1.1 401 Unauthorized');
 header('WWW-Authenticate: Digest realm="'.$realm.                                                                                                                    '",qop="auth",nonce="'.uniqid().'",opaque="'.md5($realm).'"');

 die ('Authentication failed.');
}

$sql = "SELECT password FROM users WHERE user='" . mysqli_real_escape_string($conn, $data['username']) . "';";
$result = $conn->query($sql);

if ($result->num_rows != 1) {
 header('HTTP/1.1 401 Unauthorized');
 header('WWW-Authenticate: Digest realm="'.$realm.                                                                                                                    '",qop="auth",nonce="'.uniqid().'",opaque="'.md5($realm).'"');

 die('Authentication failed.');
}

$A1 = md5($data['username'] . ':' . $realm . ':' . $result->fetch_assoc()['password']);
$A2 = md5($_SERVER['REQUEST_METHOD'].':'.$data['uri']);
$valid_response = md5($A1.':'.$data['nonce'].':'.$data['nc'].':'.$data['cnonce'].':'.$data['qop'].':'.$A2);

if ($data['response'] != $valid_response) {
 header('HTTP/1.1 401 Unauthorized');
 header('WWW-Authenticate: Digest realm="'.$realm.                                                                                                                    '",qop="auth",nonce="'.uniqid().'",opaque="'.md5($realm).'"');
 die('Authentication failed.');
}

function http_digest_parse($txt) {
 $needed_parts = array('nonce'=>1, 'nc'=>1, 'cnonce'=>1, 'qop'=>1, 'username'=>1, 'uri'=>1, 'response'=>1);
 $data = array();
 $keys = implode('|', array_keys($needed_parts));

 preg_match_all('@(' . $keys . ')=(?:([\'"])([^\2]+?)\2|([^\s,]+))@', $txt, $matches, PREG_SET_ORDER);

 foreach ($matches as $m) {
  $data[$m[1]] = $m[3] ? $m[3] : $m[4];
  unset($needed_parts[$m[1]]);
 }

 return $needed_parts ? false : $data;
}

?>