What potential issues can arise when using a download script for offering PDF files in a folder?

One potential issue that can arise when using a download script for offering PDF files in a folder is that the script may not properly handle file paths, leading to security vulnerabilities such as directory traversal attacks. To solve this issue, it is important to sanitize and validate user input to ensure that only files within the designated folder can be accessed and downloaded. 

<?php
// Get the file name from the user input
$file = $_GET['file'];

// Define the folder where the PDF files are stored
$folder = 'pdf_files/';

// Validate the file path to prevent directory traversal attacks
if (strpos($file, '/') !== false || strpos($file, '\\') !== false) {
    die('Invalid file path');
}

// Generate the full path to the PDF file
$file_path = $folder . $file;

// Check if the file exists and is a PDF file
if (file_exists($file_path) && pathinfo($file_path, PATHINFO_EXTENSION) == 'pdf') {
    // Set the appropriate headers for PDF file download
    header('Content-Type: application/pdf');
    header('Content-Disposition: attachment; filename="' . $file . '"');
    readfile($file_path);
} else {
    die('File not found or not a PDF file');
}
?>

Keywords

file permissions memory limit file size limit HTTP headers download speed

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