328 lines
8.5 KiB
PHP
328 lines
8.5 KiB
PHP
<?php
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/*
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Plugin Name: Really Simple CAPTCHA
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Plugin URI: https://contactform7.com/captcha/
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Description: Really Simple CAPTCHA is a CAPTCHA module intended to be called from other plugins. It is originally created for my Contact Form 7 plugin.
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Author: Takayuki Miyoshi
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Author URI: https://ideasilo.wordpress.com/
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Text Domain: really-simple-captcha
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Version: 2.0.1
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*/
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define( 'REALLYSIMPLECAPTCHA_VERSION', '2.0.1' );
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class ReallySimpleCaptcha {
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public $chars;
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public $char_length;
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public $fonts;
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public $tmp_dir;
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public $img_size;
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public $bg;
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public $fg;
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public $base;
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public $font_size;
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public $font_char_width;
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public $img_type;
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public $file_mode;
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public $answer_file_mode;
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public function __construct() {
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/* Characters available in images */
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$this->chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
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/* Length of a word in an image */
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$this->char_length = 4;
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/* Array of fonts. Randomly picked up per character */
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$this->fonts = array(
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dirname( __FILE__ ) . '/gentium/GenBkBasR.ttf',
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dirname( __FILE__ ) . '/gentium/GenBkBasI.ttf',
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dirname( __FILE__ ) . '/gentium/GenBkBasBI.ttf',
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dirname( __FILE__ ) . '/gentium/GenBkBasB.ttf',
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);
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/* Directory temporary keeping CAPTCHA images and corresponding text files */
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$this->tmp_dir = path_join( dirname( __FILE__ ), 'tmp' );
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/* Array of CAPTCHA image size. Width and height */
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$this->img_size = array( 72, 24 );
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/* Background color of CAPTCHA image. RGB color 0-255 */
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$this->bg = array( 255, 255, 255 );
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/* Foreground (character) color of CAPTCHA image. RGB color 0-255 */
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$this->fg = array( 0, 0, 0 );
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/* Coordinates for a text in an image. I don't know the meaning. Just adjust. */
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$this->base = array( 6, 18 );
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/* Font size */
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$this->font_size = 14;
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/* Width of a character */
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$this->font_char_width = 15;
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/* Image type. 'png', 'gif' or 'jpeg' */
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$this->img_type = 'png';
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/* Mode of temporary image files */
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$this->file_mode = 0644;
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/* Mode of temporary answer text files */
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$this->answer_file_mode = 0640;
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}
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/**
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* Generate and return a random word.
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*
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* @return string Random word with $chars characters x $char_length length
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*/
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public function generate_random_word() {
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$word = '';
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for ( $i = 0; $i < $this->char_length; $i++ ) {
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$pos = mt_rand( 0, strlen( $this->chars ) - 1 );
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$char = $this->chars[$pos];
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$word .= $char;
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}
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return $word;
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}
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/**
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* Generate CAPTCHA image and corresponding answer file.
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*
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* @param string $prefix File prefix used for both files
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* @param string $word Random word generated by generate_random_word()
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* @return string|bool The file name of the CAPTCHA image. Return false if temp directory is not available.
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*/
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public function generate_image( $prefix, $word ) {
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if ( ! $this->make_tmp_dir() ) {
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return false;
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}
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$this->cleanup();
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$dir = trailingslashit( $this->tmp_dir );
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$filename = null;
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if ( $im = imagecreatetruecolor( $this->img_size[0], $this->img_size[1] ) ) {
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$bg = imagecolorallocate( $im, $this->bg[0], $this->bg[1], $this->bg[2] );
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$fg = imagecolorallocate( $im, $this->fg[0], $this->fg[1], $this->fg[2] );
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imagefill( $im, 0, 0, $bg );
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$x = $this->base[0] + mt_rand( -2, 2 );
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for ( $i = 0; $i < strlen( $word ); $i++ ) {
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$font = $this->fonts[array_rand( $this->fonts )];
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$font = $this->normalize_path( $font );
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imagettftext( $im, $this->font_size, mt_rand( -12, 12 ), $x,
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$this->base[1] + mt_rand( -2, 2 ), $fg, $font, $word[$i] );
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$x += $this->font_char_width;
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}
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switch ( $this->img_type ) {
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case 'jpeg':
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$filename = sanitize_file_name( $prefix . '.jpeg' );
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$file = $this->normalize_path( $dir . $filename );
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imagejpeg( $im, $file );
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break;
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case 'gif':
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$filename = sanitize_file_name( $prefix . '.gif' );
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$file = $this->normalize_path( $dir . $filename );
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imagegif( $im, $file );
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break;
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case 'png':
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default:
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$filename = sanitize_file_name( $prefix . '.png' );
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$file = $this->normalize_path( $dir . $filename );
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imagepng( $im, $file );
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}
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imagedestroy( $im );
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chmod( $file, $this->file_mode );
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}
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$this->generate_answer_file( $prefix, $word );
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return $filename;
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}
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/**
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* Generate answer file corresponding to CAPTCHA image.
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*
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* @param string $prefix File prefix used for answer file
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* @param string $word Random word generated by generate_random_word()
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*/
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public function generate_answer_file( $prefix, $word ) {
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$dir = trailingslashit( $this->tmp_dir );
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$answer_file = $dir . sanitize_file_name( $prefix . '.txt' );
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$answer_file = $this->normalize_path( $answer_file );
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if ( $fh = fopen( $answer_file, 'w' ) ) {
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$word = strtoupper( $word );
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$salt = wp_generate_password( 64 );
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$hash = hash_hmac( 'md5', $word, $salt );
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$code = $salt . '|' . $hash;
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fwrite( $fh, $code );
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fclose( $fh );
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}
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chmod( $answer_file, $this->answer_file_mode );
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}
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/**
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* Check a response against the code kept in the temporary file.
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*
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* @param string $prefix File prefix used for both files
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* @param string $response CAPTCHA response
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* @return bool Return true if the two match, otherwise return false.
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*/
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public function check( $prefix, $response ) {
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if ( 0 == strlen( $prefix ) ) {
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return false;
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}
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$response = str_replace( array( " ", "\t" ), '', $response );
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$response = strtoupper( $response );
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$dir = trailingslashit( $this->tmp_dir );
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$filename = sanitize_file_name( $prefix . '.txt' );
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$file = $this->normalize_path( $dir . $filename );
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if ( is_readable( $file ) && ( $code = file_get_contents( $file ) ) ) {
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$code = explode( '|', $code, 2 );
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$salt = $code[0];
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$hash = $code[1];
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if ( hash_hmac( 'md5', $response, $salt ) == $hash ) {
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return true;
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}
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}
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return false;
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}
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/**
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* Remove temporary files with given prefix.
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*
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* @param string $prefix File prefix
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*/
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public function remove( $prefix ) {
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$dir = trailingslashit( $this->tmp_dir );
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$suffixes = array( '.jpeg', '.gif', '.png', '.php', '.txt' );
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foreach ( $suffixes as $suffix ) {
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$filename = sanitize_file_name( $prefix . $suffix );
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$file = $this->normalize_path( $dir . $filename );
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if ( is_file( $file ) ) {
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unlink( $file );
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}
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}
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}
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/**
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* Clean up dead files older than given length of time.
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*
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* @param int $minutes Consider older files than this time as dead files
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* @return int|bool The number of removed files. Return false if error occurred.
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*/
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public function cleanup( $minutes = 60, $max = 100 ) {
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$dir = trailingslashit( $this->tmp_dir );
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$dir = $this->normalize_path( $dir );
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if ( ! is_dir( $dir ) || ! is_readable( $dir ) ) {
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return false;
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}
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$is_win = ( 'WIN' === strtoupper( substr( PHP_OS, 0, 3 ) ) );
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if ( ! ( $is_win ? win_is_writable( $dir ) : is_writable( $dir ) ) ) {
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return false;
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}
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$count = 0;
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if ( $handle = opendir( $dir ) ) {
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while ( false !== ( $filename = readdir( $handle ) ) ) {
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if ( ! preg_match( '/^[0-9]+\.(php|txt|png|gif|jpeg)$/', $filename ) ) {
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continue;
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}
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$file = $this->normalize_path( $dir . $filename );
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if ( ! file_exists( $file ) || ! ( $stat = stat( $file ) ) ) {
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continue;
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}
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if ( ( $stat['mtime'] + $minutes * 60 ) < time() ) {
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if ( ! unlink( $file ) ) {
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chmod( $file, 0644 );
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unlink( $file );
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}
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$count += 1;
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}
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if ( $max <= $count ) {
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break;
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}
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}
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closedir( $handle );
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}
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return $count;
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}
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/**
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* Make a temporary directory and generate .htaccess file in it.
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*
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* @return bool True on successful create, false on failure.
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*/
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public function make_tmp_dir() {
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$dir = trailingslashit( $this->tmp_dir );
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$dir = $this->normalize_path( $dir );
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if ( ! wp_mkdir_p( $dir ) ) {
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return false;
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}
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$htaccess_file = $this->normalize_path( $dir . '.htaccess' );
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if ( file_exists( $htaccess_file ) ) {
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return true;
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}
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if ( $handle = fopen( $htaccess_file, 'w' ) ) {
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fwrite( $handle, 'Order deny,allow' . "\n" );
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fwrite( $handle, 'Deny from all' . "\n" );
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fwrite( $handle, '<Files ~ "^[0-9A-Za-z]+\\.(jpeg|gif|png)$">' . "\n" );
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fwrite( $handle, ' Allow from all' . "\n" );
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fwrite( $handle, '</Files>' . "\n" );
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fclose( $handle );
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}
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return true;
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}
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/**
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* Normalize a filesystem path.
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*
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* This should be replaced by wp_normalize_path when the plugin's
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* minimum requirement becomes WordPress 3.9 or higher.
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*
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* @param string $path Path to normalize.
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* @return string Normalized path.
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*/
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private function normalize_path( $path ) {
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$path = str_replace( '\\', '/', $path );
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$path = preg_replace( '|/+|', '/', $path );
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return $path;
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}
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}
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