Accounts, Sessions, Proxies And Intermittent Errors!

[sunny_pro]

Php Gurus,

I added a url logger to Mini Proxy so that whatever my free users browse gets logged into my db under their account usernames. The code of Mini Proxy is too long to fit into this post and so you may check it out here: https://github.com/joshdick/miniProxy/blob/master/miniProxy.php

Using the Mini Proxy, whatever I browse now gets logged into my DB. Tbl: browsing_history. Columns: ids, time & dates, usernames, urls.

Now, when I view a url it gets logged. Good.

// Dump $url into db

$stmt = mysqli_prepare($conn, "INSERT INTO 
browsing_histories(ids,usernames,urls) VALUES (?, ?, ?)");
mysqli_stmt_bind_param($stmt, 'iss', $id, $user, $url);
mysqli_stmt_execute($stmt);
if($stmt)
{
    echo "Logged $url to db a success!";
}
else    
{
    echo "Logging $url to db failed!";
}

Q1. Why is the web proxy php script only fetching "http" but not "https" pages ? Which line to change and to what to fix this ? I get error: Error: The requested URL was disallowed by the server administrator.
If you check the link for the code then you will see that error is mentioned on line 308 on the script code.

Q2. I want to fake the REFERRER so the websites (viewed via the proxy) see the referrer as: http://www.example.com/referrer.html and not the actual referrer. On which line do I add what lines of code to achieve this ?

Q3.
The Mini Proxy is a one page script. But in order to log my users browsings, I built account feature (registration.php, account_activation.php, login.php & logout.php, home.php, browser.php).
The proxy page, I renamed to browser.php.
Now, when you log-in to your account via login.php, you are redirected to home.php and the login.php sets the session:

		if (!password_verify($password, $db_password))
		{
			echo "Incorrect User Credentials!';<br>";
			exit();
		}
		else
		{
			$_SESSION["user"] = $db_username;			
			header("location:home.php?user=$db_username");

home.php & browser.php

// check if user is already logged in
if (is_logged() === false) 
{
	//Redirect user to homepage page after 2 seconds.
	header("refresh:2;url=login.php");
	exit;
}
else 
{
	$user = $_SESSION["user"];

Now, when you log-in to your account and get redirected to home.php, the session identifies your Username. So far, so good.
But, when next you navigate to browser.php then for some reason the session fails to identify your username. It's as if the session gets fropped some-ho. But, I don't understand how & why! There is no clear session in browser.php.

I am including the login.php, home.php and browser.php. I need to know why the browser.php losses the session when you go from:
-> home.php -> browser.php.

Thanks!


login.php

<?php
 
/*
ERROR HANDLING
*/
declare(strict_types=1);
ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
error_reporting(E_ALL);
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
 
include 'config.php';
 
// check if user is already logged in
if (is_logged() === true) 
{
	//Redirect user to homepage page after 2 seconds.
	header("refresh:2;url=home.php");
	exit; //
}


if (isset($_POST["login_username_or_email"]) && isset($_POST["login_password"]))
	{
		$username_or_email = trim($_POST["login_username_or_email"]);
		$password = $_POST["login_password"];		
         
		//Select Username or Email to check against Mysql DB if they are already registered or not.
				
        if(strpos("$username_or_email", "@"))
		{
			$email = $username_or_email;
						
			$query = "SELECT ids, usernames, passwords, emails, accounts_activations_statuses FROM users WHERE emails = ?";
			$stmt = mysqli_prepare($conn, $query);			
			mysqli_stmt_bind_param($stmt, 's', $email);
			mysqli_stmt_execute($stmt);
		    //$result = mysqli_stmt_get_result($stmt); //Which line to use ? This line or the next ?
			$result = mysqli_stmt_bind_result($stmt, $db_id, $db_username, $db_password, $db_email, $db_account_activation_status); // Which line to use ? This line or the one above ?
		}
		else
		{
			$username = $username_or_email;
						
			$query = "SELECT ids, usernames, passwords, emails, accounts_activations_statuses FROM users WHERE usernames = ?";
			$stmt = mysqli_prepare($conn, $query);
			mysqli_stmt_bind_param($stmt, 's', $username);
			mysqli_stmt_execute($stmt);
			$result = mysqli_stmt_bind_result($stmt, $db_id, $db_username, $db_password, $db_email, $db_account_activation_status); // Which line to use ? This line or the one above ?
		}
      	
		$row = mysqli_stmt_fetch($stmt);		
		mysqli_stmt_close($stmt);
		
		if (!password_verify($password, $db_password))
		{
			echo "Incorrect User Credentials!';<br>";
			exit();
		}
		else
		{
			$_SESSION["user"] = $db_username;			
			header("location:home.php?user=$db_username");
		}
	}

	
?>

<!DOCTYPE html>
<html>
<head>
<title><?php $site_name?> Member Login Page</title>
  <meta charset="utf-8">
</head>
<body>
<form method="post" action="">
	<h3><?= $site_name ?> Member Login Form</h3>
	<fieldset>
		<label for="login_name">Username/Email:</label>
		<input type="text" name="login_username_or_email" id="login_name" value="">
		<br>
		<label for="login_pass">Password:</label>
		<input type="password" name="login_password" id="login_pass" value="">
	</fieldset>
	<div class="submitsAndHiddens">
		<label for="login_remember">Remember Login Details:</label>
		<input type="checkbox" name="login_remember" />
		<br>
		<button type="submit">Login</button>
		<br>
		<a href="login_password_reset.php">Forgot your Password ? Reset it here!</a>
		<br>
		<a href="register.php">Register here!</a>
	</div>
</form>

</body>
</html>

home.php

browser.php

Q4.
Why does home.php show error:

Fatal error: Uncaught mysqli_sql_exception: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'FROM users WHERE usernames = ?' at line 1 in C:\xampp\htdocs\id\home.php:30 Stack trace: #0 C:\xampp\htdocs\id\home.php(30): mysqli_prepare(Object(mysqli), 'SELECT ids, use...') #1 {main} thrown in C:\xampp\htdocs\id\home.php on line 30

The code at line 30 looks like this:

$stmt = mysqli_prepare($conn, $query);

Full context of the concerned code:

$query = "SELECT ids, usernames, passwords, first_names, surnames, emails, FROM users WHERE usernames = ?";			
			[B]$stmt = mysqli_prepare($conn, $query);[/B] //This line is creating the error! But why ?
			mysqli_stmt_bind_param($stmt, 's', $user);
			mysqli_stmt_execute($stmt);
			$result = mysqli_stmt_bind_result($stmt, $id, $username, $password, $first_name, $surname, $email);
            ?>

Php Gurus,

I added a url logger to Mini Proxy so that whatever my free users browse gets logged into my db under their account usernames. The code of Mini Proxy is too long to fit into this post and so you may check it out here: https://github.com/joshdick/miniProxy/blob/master/miniProxy.php

Using the Mini Proxy, whatever I browse now gets logged into my DB. Tbl: browsing_history. Columns: ids, time & dates, usernames, urls.

Now, when I view a url it gets logged. Good.

// Dump $url into db

$stmt = mysqli_prepare($conn, "INSERT INTO 
browsing_histories(ids,usernames,urls) VALUES (?, ?, ?)");
mysqli_stmt_bind_param($stmt, 'iss', $id, $user, $url);
mysqli_stmt_execute($stmt);
if($stmt)
{
    echo "Logged $url to db a success!";
}
else    
{
    echo "Logging $url to db failed!";
}

Q1. Why is the web proxy php script only fetching "http" but not "https" pages ? Which line to change and to what to fix this ? I get error: Error: The requested URL was disallowed by the server administrator.
If you check the link for the code then you will see that error is mentioned on line 308 on the script code.

Q2. I want to fake the REFERRER so the websites (viewed via the proxy) see the referrer as: http://www.example.com/referrer.html and not the actual referrer. On which line do I add what lines of code to achieve this ?

Q3.
The Mini Proxy is a one page script. But in order to log my users browsings, I built account feature (registration.php, account_activation.php, login.php & logout.php, home.php, browser.php).
The proxy page, I renamed to browser.php.
Now, when you log-in to your account via login.php, you are redirected to home.php and the login.php sets the session:

		if (!password_verify($password, $db_password))
		{
			echo "Incorrect User Credentials!';<br>";
			exit();
		}
		else
		{
			$_SESSION["user"] = $db_username;			
			header("location:home.php?user=$db_username");

home.php & browser.php

// check if user is already logged in
if (is_logged() === false) 
{
	//Redirect user to homepage page after 2 seconds.
	header("refresh:2;url=login.php");
	exit;
}
else 
{
	$user = $_SESSION["user"];

Now, when you log-in to your account and get redirected to home.php, the session identifies your Username. So far, so good.
But, when next you navigate to browser.php then for some reason the session fails to identify your username. It's as if the session gets fropped some-ho. But, I don't understand how & why! There is no clear session in browser.php.

I am including the login.php, home.php and browser.php. I need to know why the browser.php losses the session when you go from:
-> home.php -> browser.php.

Thanks!


login.php

<?php
 
/*
ERROR HANDLING
*/
declare(strict_types=1);
ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
error_reporting(E_ALL);
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
 
include 'config.php';
 
// check if user is already logged in
if (is_logged() === true) 
{
	//Redirect user to homepage page after 2 seconds.
	header("refresh:2;url=home.php");
	exit; //
}


if (isset($_POST["login_username_or_email"]) && isset($_POST["login_password"]))
	{
		$username_or_email = trim($_POST["login_username_or_email"]);
		$password = $_POST["login_password"];		
         
		//Select Username or Email to check against Mysql DB if they are already registered or not.
				
        if(strpos("$username_or_email", "@"))
		{
			$email = $username_or_email;
						
			$query = "SELECT ids, usernames, passwords, emails, accounts_activations_statuses FROM users WHERE emails = ?";
			$stmt = mysqli_prepare($conn, $query);			
			mysqli_stmt_bind_param($stmt, 's', $email);
			mysqli_stmt_execute($stmt);
		    //$result = mysqli_stmt_get_result($stmt); //Which line to use ? This line or the next ?
			$result = mysqli_stmt_bind_result($stmt, $db_id, $db_username, $db_password, $db_email, $db_account_activation_status); // Which line to use ? This line or the one above ?
		}
		else
		{
			$username = $username_or_email;
						
			$query = "SELECT ids, usernames, passwords, emails, accounts_activations_statuses FROM users WHERE usernames = ?";
			$stmt = mysqli_prepare($conn, $query);
			mysqli_stmt_bind_param($stmt, 's', $username);
			mysqli_stmt_execute($stmt);
			$result = mysqli_stmt_bind_result($stmt, $db_id, $db_username, $db_password, $db_email, $db_account_activation_status); // Which line to use ? This line or the one above ?
		}
      	
		$row = mysqli_stmt_fetch($stmt);		
		mysqli_stmt_close($stmt);
		
		if (!password_verify($password, $db_password))
		{
			echo "Incorrect User Credentials!';<br>";
			exit();
		}
		else
		{
			$_SESSION["user"] = $db_username;			
			header("location:home.php?user=$db_username");
		}
	}

	
?>

<!DOCTYPE html>
<html>
<head>
<title><?php $site_name?> Member Login Page</title>
  <meta charset="utf-8">
</head>
<body>
<form method="post" action="">
	<h3><?= $site_name ?> Member Login Form</h3>
	<fieldset>
		<label for="login_name">Username/Email:</label>
		<input type="text" name="login_username_or_email" id="login_name" value="">
		<br>
		<label for="login_pass">Password:</label>
		<input type="password" name="login_password" id="login_pass" value="">
	</fieldset>
	<div class="submitsAndHiddens">
		<label for="login_remember">Remember Login Details:</label>
		<input type="checkbox" name="login_remember" />
		<br>
		<button type="submit">Login</button>
		<br>
		<a href="login_password_reset.php">Forgot your Password ? Reset it here!</a>
		<br>
		<a href="register.php">Register here!</a>
	</div>
</form>

</body>
</html>

home.php

<?php
 
/*
ERROR HANDLING
*/
declare(strict_types=1);
ini_set('display_errors', '1');
ini_set('display_startup_errors', '1');
error_reporting(E_ALL);
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
 
include 'config.php';
 
// check if user is already logged in
if (is_logged() === false) 
{
	//Redirect user to homepage page after 2 seconds.
	header("refresh:2;url=login.php");
	exit;
}
else 
{
	$user = $_SESSION["user"];
	echo "<a href='http://localhost/e_id/user.php?user=$user'>$user</a>";?><br>
	
	<?php 
	//Grab User details from database.
	
			$query = "SELECT ids, usernames, passwords, first_names, surnames, emails, FROM users WHERE usernames = ?";			
			$stmt = mysqli_prepare($conn, $query);
			mysqli_stmt_bind_param($stmt, 's', $user);
			mysqli_stmt_execute($stmt);
			$result = mysqli_stmt_bind_result($stmt, $id, $username, $password, $first_name, $surname, $email);
            ?>
			<html>
			<head>
			<title>
			<?php 
			$user ?> Home Page
			</title>
			</head>
			<body>
			<body background=".png">
			<?php 
			//Welcome user by name. Display log-out link.
			echo "Welcome <b><h2>$first_name $surname!"?></h2></b>|<?php echo "<p align='right'><a href='logout.php'>$user Log Out</a>";?>|</p><br>

			<?php 
			}
			?>
</body>
</html>

browser.php

<?php

/*
miniProxy - A simple PHP web proxy. <https://github.com/joshdick/miniProxy>
Written and maintained by Joshua Dick <http://joshdick.net>.
miniProxy is licensed under the GNU GPL v3 <http://www.gnu.org/licenses/gpl.html>.
*/
/****************************** START CONFIGURATION ******************************/
//To allow proxying any URL, set $whitelistPatterns to an empty array (the default).
//To only allow proxying of specific URLs (whitelist), add corresponding regular expressions
//to the $whitelistPatterns array. Enter the most specific patterns possible, to prevent possible abuse.
//You can optionally use the "getHostnamePattern()" helper function to build a regular expression that
//matches all URLs for a given hostname.
$whitelistPatterns = array(
  //Usage example: To support any URL at example.net, including sub-domains, uncomment the
  //line below (which is equivalent to [ @^https?://([a-z0-9-]+\.)*example\.net@i ]):
  //getHostnamePattern("example.net")
);
//To enable CORS (cross-origin resource sharing) for proxied sites, set $forceCORS to true.
$forceCORS = false;
//Set to false to report the client machine's IP address to proxied sites via the HTTP `x-forwarded-for` header.
//Setting to false may improve compatibility with some sites, but also exposes more information about end users to proxied sites.
$anonymize = true;
//Start/default URL that that will be proxied when miniProxy is first loaded in a browser/accessed directly with no URL to proxy.
//If empty, miniProxy will show its own landing page.
$startURL = "";
//When no $startURL is configured above, miniProxy will show its own landing page with a URL form field
//and the configured example URL. The example URL appears in the instructional text on the miniProxy landing page,
//and is proxied when pressing the 'Proxy It!' button on the landing page if its URL form is left blank.
$landingExampleURL = "https://example.net";
/****************************** END CONFIGURATION ******************************/
ob_start("ob_gzhandler");
if (version_compare(PHP_VERSION, "5.4.7", "<")) {
    die("miniProxy requires PHP version 5.4.7 or later.");
}

include 'config.php';
 
// check if user is already logged in
if (is_logged() === false) 
{
	//Redirect user to homepage page after 2 seconds.
	header("refresh:2;url=login.php");
	exit;
}
else 
{
	$user = $_SESSION["user"];
}

if (!function_exists("curl_init")) die("miniProxy requires PHP's cURL extension. Please install/enable it on your server and try again.");
//Helper function for use inside $whitelistPatterns.
//Returns a regex that matches all HTTP[S] URLs for a given hostname.
function getHostnamePattern($hostname) {
  $escapedHostname = str_replace(".", "\.", $hostname);
  return "@^https?://([a-z0-9-]+\.)*" . $escapedHostname . "@i";
}
//Helper function used to removes/unset keys from an associative array using case insensitive matching
function removeKeys(&$assoc, $keys2remove) {
  $keys = array_keys($assoc);
  $map = array();
  $removedKeys = array();
  foreach ($keys as $key) {
    $map[strtolower($key)] = $key;
  }
  foreach ($keys2remove as $key) {
    $key = strtolower($key);
    if (isset($map[$key])) {
      unset($assoc[$map[$key]]);
      $removedKeys[] = $map[$key];
    }
  }
  return $removedKeys;
}
if (!function_exists("getallheaders")) {
  //Adapted from http://www.php.net/manual/en/function.getallheaders.php#99814
  function getallheaders() {
    $result = array();
    foreach($_SERVER as $key => $value) {
      if (substr($key, 0, 5) == "HTTP_") {
        $key = str_replace(" ", "-", ucwords(strtolower(str_replace("_", " ", substr($key, 5)))));
        $result[$key] = $value;
      }
    }
    return $result;
  }
}
$usingDefaultPort =  (!isset($_SERVER["HTTPS"]) && $_SERVER["SERVER_PORT"] === 80) || (isset($_SERVER["HTTPS"]) && $_SERVER["SERVER_PORT"] === 443);
$prefixPort = $usingDefaultPort ? "" : ":" . $_SERVER["SERVER_PORT"];
//Use HTTP_HOST to support client-configured DNS (instead of SERVER_NAME), but remove the port if one is present
$prefixHost = $_SERVER["HTTP_HOST"];
$prefixHost = strpos($prefixHost, ":") ? implode(":", explode(":", $_SERVER["HTTP_HOST"], -1)) : $prefixHost;
define("PROXY_PREFIX", "http" . (isset($_SERVER["HTTPS"]) ? "s" : "") . "://" . $prefixHost . $prefixPort . $_SERVER["SCRIPT_NAME"] . "?");
//Makes an HTTP request via cURL, using request data that was passed directly to this script.
function makeRequest($url) {
  global $anonymize;
  //Tell cURL to make the request using the brower's user-agent if there is one, or a fallback user-agent otherwise.
  $user_agent = $_SERVER["HTTP_USER_AGENT"];
  if (empty($user_agent)) {
    $user_agent = "Mozilla/5.0 (compatible; miniProxy)";
  }
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_USERAGENT, $user_agent);
  //Get ready to proxy the browser's request headers...
  $browserRequestHeaders = getallheaders();
  //...but let cURL set some headers on its own.
  $removedHeaders = removeKeys($browserRequestHeaders, array(
    "Accept-Encoding", //Throw away the browser's Accept-Encoding header if any and let cURL make the request using gzip if possible.
    "Content-Length",
    "Host",
    "Origin"
  ));
  array_change_key_case($removedHeaders, CASE_LOWER);
  curl_setopt($ch, CURLOPT_ENCODING, "");
  //Transform the associative array from getallheaders() into an
  //indexed array of header strings to be passed to cURL.
  $curlRequestHeaders = array();
  foreach ($browserRequestHeaders as $name => $value) {
    $curlRequestHeaders[] = $name . ": " . $value;
  }
  if (!$anonymize) {
    $curlRequestHeaders[] = "X-Forwarded-For: " . $_SERVER["REMOTE_ADDR"];
  }
  //Any `origin` header sent by the browser will refer to the proxy itself.
  //If an `origin` header is present in the request, rewrite it to point to the correct origin.
  if (array_key_exists('origin', $removedHeaders)) {
    $urlParts = parse_url($url);
    $port = $urlParts['port'];
    $curlRequestHeaders[] = "Origin: " . $urlParts['scheme'] . "://" . $urlParts['host'] . (empty($port) ? "" : ":" . $port);
  };
  curl_setopt($ch, CURLOPT_HTTPHEADER, $curlRequestHeaders);
  //Proxy any received GET/POST/PUT data.
  switch ($_SERVER["REQUEST_METHOD"]) {
    case "POST":
      curl_setopt($ch, CURLOPT_POST, true);
      //For some reason, $HTTP_RAW_POST_DATA isn't working as documented at
      //http://php.net/manual/en/reserved.variables.httprawpostdata.php
      //but the php://input method works. This is likely to be flaky
      //across different server environments.
      //More info here: http://stackoverflow.com/questions/8899239/http-raw-post-data-not-being-populated-after-upgrade-to-php-5-3
      //If the miniProxyFormAction field appears in the POST data, remove it so the destination server doesn't receive it.
      $postData = Array();
      parse_str(file_get_contents("php://input"), $postData);
      if (isset($postData["miniProxyFormAction"])) {
        unset($postData["miniProxyFormAction"]);
      }
      curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($postData));
    break;
    case "PUT":
      curl_setopt($ch, CURLOPT_PUT, true);
      curl_setopt($ch, CURLOPT_INFILE, fopen("php://input", "r"));
    break;
  }
  //Other cURL options.
  curl_setopt($ch, CURLOPT_HEADER, true);
  curl_setopt($ch, CURLOPT_FOLLOWLOCATION, true);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  //Set the request URL.
  curl_setopt($ch, CURLOPT_URL, $url);
  //Make the request.
  $response = curl_exec($ch);
  $responseInfo = curl_getinfo($ch);
  $headerSize = curl_getinfo($ch, CURLINFO_HEADER_SIZE);
  curl_close($ch);
  //Setting CURLOPT_HEADER to true above forces the response headers and body
  //to be output together--separate them.
  $responseHeaders = substr($response, 0, $headerSize);
  $responseBody = substr($response, $headerSize);
  return array("headers" => $responseHeaders, "body" => $responseBody, "responseInfo" => $responseInfo);
}
//Converts relative URLs to absolute ones, given a base URL.
//Modified version of code found at http://nashruddin.com/PHP_Script_for_Converting_Relative_to_Absolute_URL
function rel2abs($rel, $base) {
  if (empty($rel)) $rel = ".";
  if (parse_url($rel, PHP_URL_SCHEME) != "" || strpos($rel, "//") === 0) return $rel; //Return if already an absolute URL
  if ($rel[0] == "#" || $rel[0] == "?") return $base.$rel; //Queries and anchors
  extract(parse_url($base)); //Parse base URL and convert to local variables: $scheme, $host, $path
  $path = isset($path) ? preg_replace("#/[^/]*$#", "", $path) : "/"; //Remove non-directory element from path
  if ($rel[0] == "/") $path = ""; //Destroy path if relative url points to root
  $port = isset($port) && $port != 80 ? ":" . $port : "";
  $auth = "";
  if (isset($user)) {
    $auth = $user;
    if (isset($pass)) {
      $auth .= ":" . $pass;
    }
    $auth .= "@";
  }
  $abs = "$auth$host$port$path/$rel"; //Dirty absolute URL
  for ($n = 1; $n > 0; $abs = preg_replace(array("#(/\.?/)#", "#/(?!\.\.)[^/]+/\.\./#"), "/", $abs, -1, $n)) {} //Replace '//' or '/./' or '/foo/../' with '/'
  return $scheme . "://" . $abs; //Absolute URL is ready.
}
//Proxify contents of url() references in blocks of CSS text.
function proxifyCSS($css, $baseURL) {
  // Add a "url()" wrapper to any CSS @import rules that only specify a URL without the wrapper,
  // so that they're proxified when searching for "url()" wrappers below.
  $sourceLines = explode("\n", $css);
  $normalizedLines = [];
  foreach ($sourceLines as $line) {
    if (preg_match("/@import\s+url/i", $line)) {
      $normalizedLines[] = $line;
    } else {
      $normalizedLines[] = preg_replace_callback(
        "/(@import\s+)([^;\s]+)([\s;])/i",
        function($matches) use ($baseURL) {
          return $matches[1] . "url(" . $matches[2] . ")" . $matches[3];
        },
        $line);
    }
  }
  $normalizedCSS = implode("\n", $normalizedLines);
  return preg_replace_callback(
    "/url\((.*?)\)/i",
    function($matches) use ($baseURL) {
        $url = $matches[1];
        //Remove any surrounding single or double quotes from the URL so it can be passed to rel2abs - the quotes are optional in CSS
        //Assume that if there is a leading quote then there should be a trailing quote, so just use trim() to remove them
        if (strpos($url, "'") === 0) {
          $url = trim($url, "'");
        }
        if (strpos($url, "\"") === 0) {
          $url = trim($url, "\"");
        }
        if (stripos($url, "data:") === 0) return "url(" . $url . ")"; //The URL isn't an HTTP URL but is actual binary data. Don't proxify it.
        return "url(" . PROXY_PREFIX . rel2abs($url, $baseURL) . ")";
    },
    $normalizedCSS);
}
//Proxify "srcset" attributes (normally associated with <img> tags.)
function proxifySrcset($srcset, $baseURL) {
  $sources = array_map("trim", explode(",", $srcset)); //Split all contents by comma and trim each value
  $proxifiedSources = array_map(function($source) use ($baseURL) {
    $components = array_map("trim", str_split($source, strrpos($source, " "))); //Split by last space and trim
    $components[0] = PROXY_PREFIX . rel2abs(ltrim($components[0], "/"), $baseURL); //First component of the split source string should be an image URL; proxify it
    return implode($components, " "); //Recombine the components into a single source
  }, $sources);
  $proxifiedSrcset = implode(", ", $proxifiedSources); //Recombine the sources into a single "srcset"
  return $proxifiedSrcset;
}
//Extract and sanitize the requested URL, handling cases where forms have been rewritten to point to the proxy.
if (isset($_POST["miniProxyFormAction"])) {
  $url = $_POST["miniProxyFormAction"];
  unset($_POST["miniProxyFormAction"]);
} else {
  $queryParams = Array();
  parse_str($_SERVER["QUERY_STRING"], $queryParams);
  //If the miniProxyFormAction field appears in the query string, make $url start with its value, and rebuild the the query string without it.
  if (isset($queryParams["miniProxyFormAction"])) {
    $formAction = $queryParams["miniProxyFormAction"];
    unset($queryParams["miniProxyFormAction"]);
    $url = $formAction . "?" . http_build_query($queryParams);
  } else {
    $url = substr($_SERVER["REQUEST_URI"], strlen($_SERVER["SCRIPT_NAME"]) + 1);
  }
}
if (empty($url)) {
    if (empty($startURL)) {
      die("<html><head><title>miniProxy</title></head><body><h1>Welcome to miniProxy!</h1>miniProxy can be directly invoked like this: <a href=\"" . PROXY_PREFIX . $landingExampleURL . "\">" . PROXY_PREFIX . $landingExampleURL . "</a><br /><br />Or, you can simply enter a URL below:<br /><br /><form onsubmit=\"if (document.getElementById('site').value) { window.location.href='" . PROXY_PREFIX . "' + document.getElementById('site').value; return false; } else { window.location.href='" . PROXY_PREFIX . $landingExampleURL . "'; return false; }\" autocomplete=\"off\"><input id=\"site\" type=\"text\" size=\"50\" /><input type=\"submit\" value=\"Proxy It!\" /></form></body></html>");
    } else {
      $url = $startURL;
    }
} else if (strpos($url, ":/") !== strpos($url, "://")) {
    //Work around the fact that some web servers (e.g. IIS 8.5) change double slashes appearing in the URL to a single slash.
    //See https://github.com/joshdick/miniProxy/pull/14
    $pos = strpos($url, ":/");
    $url = substr_replace($url, "://", $pos, strlen(":/"));
}
$scheme = parse_url($url, PHP_URL_SCHEME);
if (empty($scheme)) {
  //Assume that any supplied URLs starting with // are HTTP URLs.
  if (strpos($url, "//") === 0) {
    $url = "http:" . $url;
  }
} else if (!preg_match("/^https?$/i", $scheme)) {
    die('Error: Detected a "' . $scheme . '" URL. miniProxy exclusively supports http[s] URLs.');
}
//Validate the requested URL against the whitelist.
$urlIsValid = count($whitelistPatterns) === 0;
foreach ($whitelistPatterns as $pattern) {
  if (preg_match($pattern, $url)) {
    $urlIsValid = true;
    break;
  }
}
if (!$urlIsValid) {
  die("Error: The requested URL was disallowed by the server administrator.");
}
$response = makeRequest($url);
$rawResponseHeaders = $response["headers"];
$responseBody = $response["body"];
$responseInfo = $response["responseInfo"];
//If CURLOPT_FOLLOWLOCATION landed the proxy at a diferent URL than
//what was requested, explicitly redirect the proxy there.
$responseURL = $responseInfo["url"];
if ($responseURL !== $url) {
  header("Location: " . PROXY_PREFIX . $responseURL, true);
  exit(0);
}
//A regex that indicates which server response headers should be stripped out of the proxified response.
$header_blacklist_pattern = "/^Content-Length|^Transfer-Encoding|^Content-Encoding.*gzip/i";
//cURL can make multiple requests internally (for example, if CURLOPT_FOLLOWLOCATION is enabled), and reports
//headers for every request it makes. Only proxy the last set of received response headers,
//corresponding to the final request made by cURL for any given call to makeRequest().
$responseHeaderBlocks = array_filter(explode("\r\n\r\n", $rawResponseHeaders));
$lastHeaderBlock = end($responseHeaderBlocks);
$headerLines = explode("\r\n", $lastHeaderBlock);
foreach ($headerLines as $header) {
  $header = trim($header);
  if (!preg_match($header_blacklist_pattern, $header)) {
    header($header, false);
  }
}
//Prevent robots from indexing proxified pages
header("X-Robots-Tag: noindex, nofollow", true);
if ($forceCORS) {
  //This logic is based on code found at: http://stackoverflow.com/a/9866124/278810
  //CORS headers sent below may conflict with CORS headers from the original response,
  //so these headers are sent after the original response headers to ensure their values
  //are the ones that actually end up getting sent to the browser.
  //Explicit [ $replace = true ] is used for these headers even though this is PHP's default behavior.
  //Allow access from any origin.
  header("Access-Control-Allow-Origin: *", true);
  header("Access-Control-Allow-Credentials: true", true);
  //Handle CORS headers received during OPTIONS requests.
  if ($_SERVER["REQUEST_METHOD"] == "OPTIONS") {
    if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_METHOD"])) {
      header("Access-Control-Allow-Methods: GET, POST, OPTIONS", true);
    }
    if (isset($_SERVER["HTTP_ACCESS_CONTROL_REQUEST_HEADERS"])) {
      header("Access-Control-Allow-Headers: {$_SERVER['HTTP_ACCESS_CONTROL_REQUEST_HEADERS']}", true);
    }
    //No further action is needed for OPTIONS requests.
    exit(0);
  }
}
$contentType = "";
if (isset($responseInfo["content_type"])) $contentType = $responseInfo["content_type"];
//This is presumably a web page, so attempt to proxify the DOM.
if (stripos($contentType, "text/html") !== false) {
	
//DUMP THE CURRENT PAGE'S URL INTO MYSQL DB.
$conn = mysqli_connect("localhost", "root", "", "e-id");
if (!$conn) {
// message to use in development to see errors
die("Database error : " . mysqli_error($conn));
// user friendly message
// die("Database error.");
exit();
}
// Dump $url into db

$stmt = mysqli_prepare($conn, "INSERT INTO browsing_histories(ids,usernames,urls) VALUES (?, ?, ?)");
mysqli_stmt_bind_param($stmt, 'iss', $id, $user, $url);
mysqli_stmt_execute($stmt);
if($stmt)
{
    echo "Logged $url to db a success!";
}
else    
{
    echo "Logging $url to db failed!";
}

  //Attempt to normalize character encoding.
  $detectedEncoding = mb_detect_encoding($responseBody, "UTF-8, ISO-8859-1");
  if ($detectedEncoding) {
    $responseBody = mb_convert_encoding($responseBody, "HTML-ENTITIES", $detectedEncoding);
  }
  //Parse the DOM.
  $doc = new DomDocument();
  @$doc->loadHTML($responseBody);
  $xpath = new DOMXPath($doc);
  //Rewrite forms so that their actions point back to the proxy.
  foreach($xpath->query("//form") as $form) {
    $method = $form->getAttribute("method");
    $action = $form->getAttribute("action");
    //If the form doesn't have an action, the action is the page itself.
    //Otherwise, change an existing action to an absolute version.
    $action = empty($action) ? $url : rel2abs($action, $url);
    //Rewrite the form action to point back at the proxy.
    $form->setAttribute("action", rtrim(PROXY_PREFIX, "?"));
    //Add a hidden form field that the proxy can later use to retreive the original form action.
    $actionInput = $doc->createDocumentFragment();
    $actionInput->appendXML('<input type="hidden" name="miniProxyFormAction" value="' . htmlspecialchars($action) . '" />');
    $form->appendChild($actionInput);
  }
  //Proxify <meta> tags with an 'http-equiv="refresh"' attribute.
  foreach ($xpath->query("//meta[@http-equiv]") as $element) {
    if (strcasecmp($element->getAttribute("http-equiv"), "refresh") === 0) {
      $content = $element->getAttribute("content");
      if (!empty($content)) {
        $splitContent = preg_split("/=/", $content);
        if (isset($splitContent[1])) {
          $element->setAttribute("content", $splitContent[0] . "=" . PROXY_PREFIX . rel2abs($splitContent[1], $url));
        }
      }
    }
  }
  //Profixy <style> tags.
  foreach($xpath->query("//style") as $style) {
    $style->nodeValue = proxifyCSS($style->nodeValue, $url);
  }
  //Proxify tags with a "style" attribute.
  foreach ($xpath->query("//*[@style]") as $element) {
    $element->setAttribute("style", proxifyCSS($element->getAttribute("style"), $url));
  }
  //Proxify "srcset" attributes in <img> tags.
  foreach ($xpath->query("//img[@srcset]") as $element) {
    $element->setAttribute("srcset", proxifySrcset($element->getAttribute("srcset"), $url));
  }
  //Proxify any of these attributes appearing in any tag.
  $proxifyAttributes = array("href", "src");
  foreach($proxifyAttributes as $attrName) {
    foreach($xpath->query("//*[@" . $attrName . "]") as $element) { //For every element with the given attribute...
      $attrContent = $element->getAttribute($attrName);
      if ($attrName == "href" && preg_match("/^(about|javascript|magnet|mailto):/i", $attrContent)) continue;
      $attrContent = rel2abs($attrContent, $url);
      $attrContent = PROXY_PREFIX . $attrContent;
      $element->setAttribute($attrName, $attrContent);
    }
  }
  //Attempt to force AJAX requests to be made through the proxy by
  //wrapping window.XMLHttpRequest.prototype.open in order to make
  //all request URLs absolute and point back to the proxy.
  //The rel2abs() JavaScript function serves the same purpose as the server-side one in this file,
  //but is used in the browser to ensure all AJAX request URLs are absolute and not relative.
  //Uses code from these sources:
  //http://stackoverflow.com/questions/7775767/javascript-overriding-xmlhttprequest-open
  //https://gist.github.com/1088850
  //TODO: This is obviously only useful for browsers that use XMLHttpRequest but
  //it's better than nothing.
  $head = $xpath->query("//head")->item(0);
  $body = $xpath->query("//body")->item(0);
  $prependElem = $head != NULL ? $head : $body;
  //Only bother trying to apply this hack if the DOM has a <head> or <body> element;
  //insert some JavaScript at the top of whichever is available first.
  //Protects against cases where the server sends a Content-Type of "text/html" when
  //what's coming back is most likely not actually HTML.
  //TODO: Do this check before attempting to do any sort of DOM parsing?
  if ($prependElem != NULL) {
    $scriptElem = $doc->createElement("script",
      '(function() {
        if (window.XMLHttpRequest) {
          function parseURI(url) {
            var m = String(url).replace(/^\s+|\s+$/g, "").match(/^([^:\/?#]+:)?(\/\/(?:[^:@]*(?::[^:@]*)?@)?(([^:\/?#]*)(?::(\d*))?))?([^?#]*)(\?[^#]*)?(#[\s\S]*)?/);
            // authority = "//" + user + ":" + pass "@" + hostname + ":" port
            return (m ? {
              href : m[0] || "",
              protocol : m[1] || "",
              authority: m[2] || "",
              host : m[3] || "",
              hostname : m[4] || "",
              port : m[5] || "",
              pathname : m[6] || "",
              search : m[7] || "",
              hash : m[8] || ""
            } : null);
          }
          function rel2abs(base, href) { // RFC 3986
            function removeDotSegments(input) {
              var output = [];
              input.replace(/^(\.\.?(\/|$))+/, "")
                .replace(/\/(\.(\/|$))+/g, "/")
                .replace(/\/\.\.$/, "/../")
                .replace(/\/?[^\/]*/g, function (p) {
                  if (p === "/..") {
                    output.pop();
                  } else {
                    output.push(p);
                  }
                });
              return output.join("").replace(/^\//, input.charAt(0) === "/" ? "/" : "");
            }
            href = parseURI(href || "");
            base = parseURI(base || "");
            return !href || !base ? null : (href.protocol || base.protocol) +
            (href.protocol || href.authority ? href.authority : base.authority) +
            removeDotSegments(href.protocol || href.authority || href.pathname.charAt(0) === "/" ? href.pathname : (href.pathname ? ((base.authority && !base.pathname ? "/" : "") + base.pathname.slice(0, base.pathname.lastIndexOf("/") + 1) + href.pathname) : base.pathname)) +
            (href.protocol || href.authority || href.pathname ? href.search : (href.search || base.search)) +
            href.hash;
          }
          var proxied = window.XMLHttpRequest.prototype.open;
          window.XMLHttpRequest.prototype.open = function() {
              if (arguments[1] !== null && arguments[1] !== undefined) {
                var url = arguments[1];
                url = rel2abs("' . $url . '", url);
                url = "' . PROXY_PREFIX . '" + url;
                arguments[1] = url;
              }
              return proxied.apply(this, [].slice.call(arguments));
          };
        }
      })();'
    );
    $scriptElem->setAttribute("type", "text/javascript");
    $prependElem->insertBefore($scriptElem, $prependElem->firstChild);
  }
  echo "<!-- Proxified page constructed by miniProxy -->\n" . $doc->saveHTML();
} else if (stripos($contentType, "text/css") !== false) { //This is CSS, so proxify url() references.
  echo proxifyCSS($responseBody, $url);
} else { //This isn't a web page or CSS, so serve unmodified through the proxy with the correct headers (images, JavaScript, etc.)
  header("Content-Length: " . strlen($responseBody), true);
  echo $responseBody;
}

Q4.
Why does home.php show error:

Fatal error: Uncaught mysqli_sql_exception: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'FROM users WHERE usernames = ?' at line 1 in C:\xampp\htdocs\id\home.php:30 Stack trace: #0 C:\xampp\htdocs\id\home.php(30): mysqli_prepare(Object(mysqli), 'SELECT ids, use...') #1 {main} thrown in C:\xampp\htdocs\id\home.php on line 30

The code at line 30 looks like this:

$stmt = mysqli_prepare($conn, $query);

Full context of the concerned code:

$query = "SELECT ids, usernames, passwords, first_names, surnames, emails, FROM users WHERE usernames = ?";			
			[B]$stmt = mysqli_prepare($conn, $query);[/B] //This line is creating the error! But why ?
			mysqli_stmt_bind_param($stmt, 's', $user);
			mysqli_stmt_execute($stmt);
			$result = mysqli_stmt_bind_result($stmt, $id, $username, $password, $first_name, $surname, $email);
            ?>