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