Develop Reference

Prevent Direct access to PHP file using AJAX

I want to prevent direct access to a certain PHP file called prevented.php
My logic is that I have a main file lets call it index.php and it generates a token and stores it in a $_SESSION variable. I also have a another file called def.php which is called using AJAX and it passes the token from the index.php to the def.php and if the $_SESSION['token'] is equal to the $_POST['token'] it defines a _DEFVAR and returns true otherwise it returns false. After I called the def.php and it returns true, I redirect to the prevented.php via javascript using location.href="prevented.php". In the top of the prevented.php file there is a code which checks if the _DEFVAR is defined or not. If not, its die with a message like invalid otherwise it displays the content of the prevented.php file. But somewhy I always get invalid message and I don't know why. Any idea how to reach the prevented.php without directly direct the page?
Here's my code:
index.php
<?php
$_SESSION["token"] = hash_hmac('sha256', "tokenString", "t2o0k0e0n3"); // Creates a hashed token
?>
<script>
$.ajax({
type: "POST",
url: "def.php",
data: {
token: '<?php echo $_SESSION["token"]; ?>'
},
cache: false,
success: function(data) {
console.log (data);
if (data) {
console.log (data + ' valid');
} else {
console.log (data + ' invalid');
}
location.href = "prevented.php";
},
error: function () {
console.log('error');
}
});
</script>
def.php
<?php
session_start();
if (!isset($_POST['token']) || $_POST['token'] != $_SESSION['token']) {
echo false;
die('invalid in def');
} else {
define('_DEFVAR', 1);
echo true;
die ('valid in def');
}
?>
prevented.php
<?php
include "def.php";
if (defined('_DEFVAR')) {
die ('valid in prevented'); // instead of this I would show the content of the page
} else {
die ('invalid in prevented');
}
?>

Your code is unnecessarily overcomplicated. If your intent is merely to ensure that visitors to protected.php have first visited index.php then all you need to do is create a session flag in one and check for its existence in the other. There is no need for any AJAX or any form POSTs. The innate behavior of PHP sessions already gives you this functionality.
index.php:
<?php
session_start();
$_SESSION['flag'] = true;
?>
click here for the protected page
protected.php:
<?php
session_start();
if ($_SESSION['flag'] ?? false) {
echo "you have previously visited index.php";
} else {
echo "you have not previously visited index.php";
}
?>

Recode login page from JS and PHP to just JS... is it possible?

I just finished coding a simple login page with JS and PHP. However, my boss wants me to redo it without the PHP.
HOWEVER, he kept saying that to do that, I should be sending data to "http" (that's literally what he said) and I'm not quite sure what he means. He might have been talking about HttpServletRequests, but I am honestly not sure because there's a language barrier (his first language is Chinese).
To redo this code without PHP, are HttpServletRequests necessary or is there another, simpler way to do it?
login.js
$(document).ready(function() {
$("#submit").click(function() {
var action = $("#form1").attr('action');
var form_data = {
username: $("#username").val(),
password: $.md5($("#password").val()),
is_ajax: 1
};
$.ajax({
type: "POST",
url: action,
data: form_data,
success: function(response) {
if(response.trim() == "success") {
$("#form1").slideUp('slow', function() {
$("#message").html("<p class='success'>You have logged in successfully!</p>");
})
}
else {
$("#message").html("<p class='error'>Invalid username and/or password.</p>");
}
}
});
return false;
});
});
doLogin.php
<?php
session_start();
$host="localhost";
$username="root";
$password="";
$db_name="test";
$tbl_name="usertable";
$response="";
$connection =
mysqli_connect("$host", "$username", "$password", "$db_name")or die("Unable to connect.");
$myusername=$_POST['username'];
$mypassword=$_POST['password'];
$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysqli_query($connection, $sql);
$count=mysqli_num_rows($result);
if ($count==1) {
echo "success";
}
else {
echo $count;
echo 'failure';
}
mysqli_close($connection);
?>
Also, I understand that the code above may be faulty and filled with security risks and bad practises and I apologize for that.

Validating availability using javascript and php

I want to make a javascript function which checks the database whether the id requested by the user is available or not. My code is:
HTML:
<button type="button" onclick="chkId()">Check Availability</button><span id="chkresult"></span>
Javascript code:
function chkId()
{
$("#chkresult").html("Please wait...");
$.get("check_id.php", function(data) { $("#chkresult").html(data); });
}
The check_id.php file:
<?php
require 'connect.php';
$id_query = mysql_query("SELECT COUNT(*) AS TOTAL FROM `Table4` WHERE `Unique ID` = '$id'");
list ($total) = mysql_fetch_row($id_query);
if ($total == 0)
{
echo "Available!";
}
else if ($total > 0)
{
echo "Not Available!";
}
?>
But when the button is clicked, nothing happens. I just get a 'Please wait...' message, but as expected by the code, after 'Please wait...' it should change either to Available or to Not Available. But I only get the 'Please Wait...' message, and the result Available or Not Available is not printed on the screen. Please help me what changes do I need to make in my code.

I do not see the $id variable in your PHP script that is used by your $id_query.
Try adding that above $id_query

A few things I notice:
Your javascript is not passing the id parameter to your php backend. See the documentation for the proper syntax to pass that id param.
Your PHP is calling the mysql_query method and one of the parameters that it is passing in is the $id - but $id has not been declared. Check your PHP logs and you'll see where it is choking.
Because the PHP code is likely failing due to the unresolved variable, it is returning an error code. When JQuery receives the error code, it goes to call your ajax failure handler, but you have not declared one! Try adding a .fail(function(){}); to your get call as the docs describe - and you'll likely see the php error message show up.
EDIT: Obligatory php sql injection attack warning. Make sure to escape client input!!!

$.ajax({
type: "POST",
url: "check_id.php",
data: {
id:id; //the id requested by the user.You should set this
},
dataType: "json",
success: function(data){
$('#chkresult').html(data);
}
},
failure: function(errMsg) {
alert(errMsg);
}
});
In your php
<?php
require 'connect.php';
$id_query = mysql_query("SELECT COUNT(*) AS TOTAL FROM `Table4` WHERE `Unique ID` = '$id'");
list ($total) = mysql_fetch_row($id_query);
if ($total == 0)
{
header('Content-type: application/json');
echo CJavaScript::jsonEncode('Available');
}
else if ($total > 0)
{
header('Content-type: application/json');
echo CJavaScript::jsonEncode('Not available');
}
?>

How can I attach the POST variable values to a new SESSION variable in AJAX and call it from other script?

I checked the accepted answer of this question it but didn't help
I'm trying to make an AJAX Post Request to sumbit my signup form, the ajax.php file will check the entered information, example passwords match or not, and then attach the $_POST variable to a $_SESSION variable so that I can call the submitted data from any other page later.
Ajax.php
...
if ($everythingValid) {
// add this user to db
$_SESSION["signup_details"] = $_POST;
echo "SUCCESS#".$core->signupPaymentUrl($package); // tried without this line but didn't work
exit(); // tried without this line but didn't work
} else {
foreach ($errors as $e) print "<br>".$e;
exit();
}
...
The jquery code that I'm using to call the file is the below:
var form = $('#signup');
$("#submit").click(function() {
$.ajax( {
type: "POST",
dataType: 'html',
crossDomain: true,
url: form.attr( 'action' ),
data: form.serialize(),
success: function( response ) {
if ("SUCCESS" === $.trim(response.split('#')[0])) {
// user created, redirect to payment page
var paymentUrl = $.trim(response.split('#')[1]);
window.location.href = paymentUrl;
} else {
$("b#signupErr").hide();
$("b#signupErr").html(response);
$("b#signupErr").fadeIn();
}
}
} );
});
After submitting the form, I successfully get redirected to the payment Url, however, after accessing the page where I want to use my session, I cannot figure out how to retrieve my session although I'm pretty sure that I have included session_start in both of ajax.php and completeOrder.php and no blank spaces before the opening php tag.
here is the line that I included in both files :
if(!session_id()) session_start();
I tried to var_dump the $_SESSION variable on ajax.php and It looks okay. However when I var_dump the session variable on completeOrder.php it shows me NULL
Finally here is the completeOrder.php content
if(!session_id()) session_start();
require_once("core.php");
$core = new coreOptions();
$email = $_SESSION["signup_details"]["email"];
$password = $_SESSION["signup_details"]["password"];
$package = $_SESSION["signup_details"]["pkg"];
$options = $core->attachOptions($package);
if ($core->registerUser($email,$password,$options,$package))
$core->redirect("registrationCompleted.php");

in the completeOrder.php file remove if(!session_id()) session_start();
and then only add session_start(); and it will do the trick!

session_id() will return an empty string in ajax.php if there was no call to session_start() before. So the in ajax.php session_start() will never be called and the content of $_SESSION won't be stored anywhere.
So just use:
session_start();
in both files.

Trying to show sucess message with jQuery concatenated with php echo

Im trying to do a recover password system with jQuery messages and Im having a problem.
The code below is working fine, when I click in the button to recover my username and password I get the message <p class="sucess">Email sent with your data..</p>.
But I want to put the email of the user in the message. Like this:
<p class="sucess">Email sent with your data for email#example.com!</p>
Im trying like this in my php
else {
echo 'sucess'; //here I show the jQuery message
echo $result['email']; //and then I want to show my $result['email']
return;
}
I already try like this:
echo 'sucess'.$result['email'].'';
But I have always the same problem, Im entering here in my jQuery:
else
{
alert('Error in system');
}
And if I dont put this echo in $result['email'] the sucess message works fine, but when I try to echo my $result['email'] Im always entering in this jQuery condition.
Somebody there have any idea why this is happening?
My php:
switch ($action){
case 'recover':
$email = $_POST['email'];
if($email == ''){
echo 'errorempty';
}else{
$searchEmail = $pdo->prepare("SELECT * FROM admins WHERE email=:email");
$searchEmail->bindValue(":email", $email);
$searchEmail->execute();
$num_rows = $searchEmail->rowCount();
$result = $searchEmail->fetch(PDO::FETCH_ASSOC);
if($num_rows <=0 )
{
echo 'erroremail';
return;
}
else {
echo 'sucess';
echo $result['email'];
return;
}
}
break;
default:
echo 'Error';
}
}
My jQuery:
$('#recover').submit(function(){
var login = $(this).serialize() + '&action=recover';
$.ajax({
url: 'switch/login.php',
data: login,
type: 'POST',
success: function(answer){
if(answer== 'erroempty'){
$('.msg').empty().html('<p class="warning">Inform your email!</p>').fadeIn('slow');
}
else if (answer == 'erroemail'){
$('.msg').empty().html('<p class="error">Email dont exist!</p>').fadeIn('slow');
}
else if(answer == 'sucess'){
$('.msg').empty().html('<p class="sucess">Email sent with your data..</p>').fadeIn('slow');
window.setTimeout(function(){
$(location).attr('href','dashboard.php');
},1000);
}
else{
alert('Error in system');
}
},
beforeSend: function(){
$('.loginbox h1 img').fadeIn('fast');
},
complete: function(){
$('.loginbox h1 img').fadeOut('slow');
},
error: function(){
alert('Error in system');
}
});
return false;
});

you can simple echo the $email like this
$email=$result["email"];
echo $email;
then in ajax success function
if(answer.email)
{
$('.msg').empty().html('<p class="sucess">Email sent with your data..'+answer.email+'</p>').fadeIn('slow');
}

The problem is, that you server side is returning just unstructured data and the client side part will just receive a plain string like sucessdummy#example.com in the answer variable.
This answer variable is compared with strings that do not match thought your script ends in the error case. I would go for a solution by returning some kind of structured data like json.
Your server side code could look something like
$result = array('msg'=>'success','mail'=>$result['email']);
header('Content-type: application/json');
echo json_encode($result);
You have to pass the dataType:'json' option in your jquery ajax call to make it work and can access the data in the call back function like answer.msg, answer.mail