PDO reads the database, but does not log into system - Phpmyadmin

ChristianAH
March 19, 2019
137 views
0 votes
2 Answers

I currently have a login system, which I would like to convert to PDO from Mysqli.

I currently have a website with a database attached with phpMyAdmin/MySQL.

I tried to convert everything and I will now show you the LOGIN.php part of the system since I haven’t touched the signup part yet.

This is what I have.

    <?php

require_once 'dbh.inc.php';

try {
    $handler = new PDO("mysql:host=$servername;dbname=$dbname",
    $username,
    $password,
    array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));
  } catch(PDOException $e){
    echo $e->getName();
    die();
  }

//first we start a session
session_start();

//We then check if the user has clicked the login button
if (isset($_POST['submit'])) {

    //Then we require the database connection
    //require_once 'dbh.inc.php';
    //And we get the data from the login form
    $name = $_POST['name'];
    $password = $_POST['password'];

    //Error handlers
    //Error handlers are important to avoid any mistakes the user might have made when filling out the form!
    //Check if inputs are empty
    if (empty($name) || empty($password)) {
        header("Location: ../index.php?login=empty");
        exit();
    }   
    } else {
        $stmt = $db->prepare("SELECT * FROM users WHERE user_name=:name");
        $stmt->bindParam(':name', $name, PDO::PARAM_STR);

        if ($stmt->execute()) {
            header("location: ../index.php?login=error");
            exit();
        } else { 
            if ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
            //de-hashing the password
            $hashedpasswordCheck = password_verify($password, $row['user_password']);
            if ($hashedpasswordCheck == false) {
              header("location: ../index.php?login=error");
              exit();

            } elseif ($hashedpasswordCheck == true) {
                //Log in the user here
                $_SESSION['u_id'] = $row['user_id'];
                $_SESSION['u_name'] = $row['user_name'];
                header("location: ../index.php?login=success");
                exit();
              }
            } else {
                header("location: ../index.php?login=error");
                exit();
              }     
        }  
      }

DBH.INC.PHP

    <?php

$servername = "localhost";
$username = "root";
$password = "";
$dbname = "loginsystem";


try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname",
    $username,
    $password,
    array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));

    $stmt = $conn->prepare("SHOW DATABASES;");

    $stmt->execute();
    $stmt->setFetchMode(PDO::FETCH_ASSOC);
    $result = $stmt->fetchAll();
    print_r($result);


}
catch(PDOException $e) {
    echo $e->getMessage();
}

$conn = null;

When I try to login I get redirected to this url:

http://localhost/php44/includes/login.inc.php

and receive this printed message/error.

Array ( [0] => Array ( [Database] => imgupload ) [1] => Array ( [Database] => information_schema ) [2] => Array ( [Database] => loginsystem ) [3] => Array ( [Database] => mysql ) [4] => Array ( [Database] => performance_schema ) [5] => Array ( [Database] => phpmyadmin ) [6] => Array ( [Database] => test ) )

What should I do to fix this, so that my login works?

Answers

I’ve made some fixes and added comments in to explain what changed:

<?php

//First we start a session
session_start();

//Then we require the database connection
require_once 'dbh.inc.php';

// Removed the extra database connection here.

//We then check if the user has clicked the login button
if (isset($_POST['submit'])) {

    //And we get the data from the login form
    $name = $_POST['name'];
    $password = $_POST['password'];

    //Error handlers
    //Error handlers are important to avoid any mistakes the user might have made when filling out the form!
    //Check if inputs are empty
    if (empty($name) || empty($password)) {
        header("Location: ../index.php?login=empty");
        exit();
    }   
//Removed extra 'else' here.
    $stmt = $conn->prepare("SELECT * FROM users WHERE user_name=:name");  // Changed $db to $conn to use the connection from DBH.INC.PHP
    $stmt->bindParam(':name', $name, PDO::PARAM_STR);

    if (!$stmt->execute()) {   // Added the ! to say "if this doesn't work, redirect to error"
        header("location: ../index.php?login=error");
        exit();
    } else { 
        if ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
            //de-hashing the password
            $hashedpasswordCheck = password_verify($password, $row['user_password']);
            if ($hashedpasswordCheck == false) {
                header("location: ../index.php?login=error");
                exit();
            } else if ($hashedpasswordCheck == true) {
                //Log in the user here
                $_SESSION['u_id'] = $row['user_id'];
                $_SESSION['u_name'] = $row['user_name'];
                header("location: ../index.php?login=success");
                exit();
            }
        } else {
        header("location: ../index.php?login=error");
        exit();
        }     
    }  
}

DB.INC.PHP

<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "loginsystem";

try {
    $conn = new PDO("mysql:host=$servername;dbname=$dbname",
    $username,
    $password,
    array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION));

    // Removed the query and print of the databases

  }
catch(PDOException $e) {
    echo $e->getMessage();
}
// Removed the $conn=null to keep the connection we just set up.

Your code is vulnerable to Html Elements Injection and session fixation attack. I have implemented strip_tags() to prevents html element injection attack and have also implemented session_regenerate_id(); to prevent session fixation attack.

Again since you are login, you only need to initialize session as soon as username and password is verified.

As for me, I prefer using PDO array method. Anyway I have provided two solution. I first work on your code and then modify it were appropriate. Ensure that database credentials is okay

Your code

<?php

//db connect starts
$db = new PDO (
    'mysql:host=localhost;dbname=loginsystem;charset=utf8', 
    'root', // username

    '' // password
);



//We then check if the user has clicked the login button
if (isset($_POST['submit'])) {
    $name = $_POST['name'];
    $password = $_POST['password'];

    if ($name =='' && $password =='') {
        header("Location: ../index.php?login=empty");
        exit();
    } 


        $stmt = $db->prepare("SELECT * FROM users WHERE user_name=:name");
        $stmt->bindParam(':name', $name, PDO::PARAM_STR);
        $stmt->execute();

$count = $stmt->rowCount();
if( $count == 1 ) {
$row = $stmt->fetch();
if(password_verify($password,$row['password'])){
            echo "Password verified and ok";

// initialize session if things where ok.
session_start();

//Prevent session fixation attack
session_regenerate_id();

$_SESSION['u_id'] = $row['user_id'];
$_SESSION['u_name'] = $row['user_name'];
header("location: ../index.php?login=success");
exit();


        }
        else{
            echo "Wrong Password details";
        }
}
else {

echo "User does not exist";
}
}
?>

my code

<?php

//if (isset($_POST['submit'])) {
if ($_POST['name'] !='' && $_POST['password']) {

//connect 
$db = new PDO (
    'mysql:host=localhost;dbname=loginsystem;charset=utf8', 
    'root', // username

    '' // password
);

$name = strip_tags($_POST['name']);
$password = strip_tags($_POST['password']);

if ($name == ''){
echo "Username is empty";
exit();
}
if ($password == ''){
echo "password is empty";
exit();
}

$result = $db->prepare('SELECT * FROM users where user_name = :name');
        $result->execute(array(
            ':user_name' => $name));
$count = $result->rowCount();
if( $count == 1 ) {
$row = $result->fetch();

  if(password_verify($password,$row['password'])){
            echo "Password verified and ok";

// initialize session if things where ok.
session_start();

//Prevent session fixation attack
session_regenerate_id();

$_SESSION['u_id'] = $row['user_id'];
$_SESSION['u_name'] = $row['user_name'];
header("location: ../index.php?login=success");
exit();


        }
        else{
            echo "Wrong Password details";
        }
}
else {

echo "User does not exist";
}

}

?>

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PDO reads the database, but does not log into system – Phpmyadmin

Answers