really-simple-captcha / really-simple-captcha.php

really-simple-captcha.php in Really Simple CAPTCHA 2.0, at really-simple-captcha.php

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1	<?php
2	/*
3	Plugin Name: Really Simple CAPTCHA
4	Plugin URI: https://contactform7.com/captcha/
5	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.
6	Author: Takayuki Miyoshi
7	Author URI: https://ideasilo.wordpress.com/
8	Text Domain: really-simple-captcha
9	Version: 2.0
10	*/
11
12	define( 'REALLYSIMPLECAPTCHA_VERSION', '2.0' );
13
14	class ReallySimpleCaptcha {
15
16	public $chars;
17	public $char_length;
18	public $fonts;
19	public $tmp_dir;
20	public $img_size;
21	public $bg;
22	public $fg;
23	public $base;
24	public $font_size;
25	public $font_char_width;
26	public $img_type;
27	public $file_mode;
28	public $answer_file_mode;
29
30	public function __construct() {
31	/* Characters available in images */
32	$this->chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
33
34	/* Length of a word in an image */
35	$this->char_length = 4;
36
37	/* Array of fonts. Randomly picked up per character */
38	$this->fonts = array(
39	dirname( __FILE__ ) . '/gentium/GenBkBasR.ttf',
40	dirname( __FILE__ ) . '/gentium/GenBkBasI.ttf',
41	dirname( __FILE__ ) . '/gentium/GenBkBasBI.ttf',
42	dirname( __FILE__ ) . '/gentium/GenBkBasB.ttf',
43	);
44
45	/* Directory temporary keeping CAPTCHA images and corresponding text files */
46	$this->tmp_dir = path_join( dirname( __FILE__ ), 'tmp' );
47
48	/* Array of CAPTCHA image size. Width and height */
49	$this->img_size = array( 72, 24 );
50
51	/* Background color of CAPTCHA image. RGB color 0-255 */
52	$this->bg = array( 255, 255, 255 );
53
54	/* Foreground (character) color of CAPTCHA image. RGB color 0-255 */
55	$this->fg = array( 0, 0, 0 );
56
57	/* Coordinates for a text in an image. I don't know the meaning. Just adjust. */
58	$this->base = array( 6, 18 );
59
60	/* Font size */
61	$this->font_size = 14;
62
63	/* Width of a character */
64	$this->font_char_width = 15;
65
66	/* Image type. 'png', 'gif' or 'jpeg' */
67	$this->img_type = 'png';
68
69	/* Mode of temporary image files */
70	$this->file_mode = 0644;
71
72	/* Mode of temporary answer text files */
73	$this->answer_file_mode = 0640;
74	}
75
76	/**
77	* Generate and return a random word.
78	*
79	* @return string Random word with $chars characters x $char_length length
80	*/
81	public function generate_random_word() {
82	$word = '';
83
84	for ( $i = 0; $i < $this->char_length; $i++ ) {
85	$pos = mt_rand( 0, strlen( $this->chars ) - 1 );
86	$char = $this->chars[$pos];
87	$word .= $char;
88	}
89
90	return $word;
91	}
92
93	/**
94	* Generate CAPTCHA image and corresponding answer file.
95	*
96	* @param string $prefix File prefix used for both files
97	* @param string $word Random word generated by generate_random_word()
98	* @return string\|bool The file name of the CAPTCHA image. Return false if temp directory is not available.
99	*/
100	public function generate_image( $prefix, $word ) {
101	if ( ! $this->make_tmp_dir() ) {
102	return false;
103	}
104
105	$this->cleanup();
106
107	$dir = trailingslashit( $this->tmp_dir );
108	$filename = null;
109
110	if ( $im = imagecreatetruecolor( $this->img_size[0], $this->img_size[1] ) ) {
111	$bg = imagecolorallocate( $im, $this->bg[0], $this->bg[1], $this->bg[2] );
112	$fg = imagecolorallocate( $im, $this->fg[0], $this->fg[1], $this->fg[2] );
113
114	imagefill( $im, 0, 0, $bg );
115
116	$x = $this->base[0] + mt_rand( -2, 2 );
117
118	for ( $i = 0; $i < strlen( $word ); $i++ ) {
119	$font = $this->fonts[array_rand( $this->fonts )];
120	$font = $this->normalize_path( $font );
121
122	imagettftext( $im, $this->font_size, mt_rand( -12, 12 ), $x,
123	$this->base[1] + mt_rand( -2, 2 ), $fg, $font, $word[$i] );
124	$x += $this->font_char_width;
125	}
126
127	switch ( $this->img_type ) {
128	case 'jpeg':
129	$filename = sanitize_file_name( $prefix . '.jpeg' );
130	$file = $this->normalize_path( $dir . $filename );
131	imagejpeg( $im, $file );
132	break;
133	case 'gif':
134	$filename = sanitize_file_name( $prefix . '.gif' );
135	$file = $this->normalize_path( $dir . $filename );
136	imagegif( $im, $file );
137	break;
138	case 'png':
139	default:
140	$filename = sanitize_file_name( $prefix . '.png' );
141	$file = $this->normalize_path( $dir . $filename );
142	imagepng( $im, $file );
143	}
144
145	imagedestroy( $im );
146	chmod( $file, $this->file_mode );
147	}
148
149	$this->generate_answer_file( $prefix, $word );
150
151	return $filename;
152	}
153
154	/**
155	* Generate answer file corresponding to CAPTCHA image.
156	*
157	* @param string $prefix File prefix used for answer file
158	* @param string $word Random word generated by generate_random_word()
159	*/
160	public function generate_answer_file( $prefix, $word ) {
161	$dir = trailingslashit( $this->tmp_dir );
162	$answer_file = $dir . sanitize_file_name( $prefix . '.txt' );
163	$answer_file = $this->normalize_path( $answer_file );
164
165	if ( $fh = fopen( $answer_file, 'w' ) ) {
166	$word = strtoupper( $word );
167	$salt = wp_generate_password( 64 );
168	$hash = hash_hmac( 'md5', $word, $salt );
169	$code = $salt . '\|' . $hash;
170	fwrite( $fh, $code );
171	fclose( $fh );
172	}
173
174	chmod( $answer_file, $this->answer_file_mode );
175	}
176
177	/**
178	* Check a response against the code kept in the temporary file.
179	*
180	* @param string $prefix File prefix used for both files
181	* @param string $response CAPTCHA response
182	* @return bool Return true if the two match, otherwise return false.
183	*/
184	public function check( $prefix, $response ) {
185	if ( 0 == strlen( $prefix ) ) {
186	return false;
187	}
188
189	$response = str_replace( array( " ", "\t" ), '', $response );
190	$response = strtoupper( $response );
191
192	$dir = trailingslashit( $this->tmp_dir );
193	$filename = sanitize_file_name( $prefix . '.txt' );
194	$file = $this->normalize_path( $dir . $filename );
195
196	if ( is_readable( $file ) && ( $code = file_get_contents( $file ) ) ) {
197	$code = explode( '\|', $code, 2 );
198	$salt = $code[0];
199	$hash = $code[1];
200
201	if ( hash_hmac( 'md5', $response, $salt ) == $hash ) {
202	return true;
203	}
204	}
205
206	return false;
207	}
208
209	/**
210	* Remove temporary files with given prefix.
211	*
212	* @param string $prefix File prefix
213	*/
214	public function remove( $prefix ) {
215	$dir = trailingslashit( $this->tmp_dir );
216	$suffixes = array( '.jpeg', '.gif', '.png', '.php', '.txt' );
217
218	foreach ( $suffixes as $suffix ) {
219	$filename = sanitize_file_name( $prefix . $suffix );
220	$file = $this->normalize_path( $dir . $filename );
221
222	if ( is_file( $file ) ) {
223	unlink( $file );
224	}
225	}
226	}
227
228	/**
229	* Clean up dead files older than given length of time.
230	*
231	* @param int $minutes Consider older files than this time as dead files
232	* @return int\|bool The number of removed files. Return false if error occurred.
233	*/
234	public function cleanup( $minutes = 60, $max = 100 ) {
235	$dir = trailingslashit( $this->tmp_dir );
236	$dir = $this->normalize_path( $dir );
237
238	if ( ! is_dir( $dir ) \|\| ! is_readable( $dir ) ) {
239	return false;
240	}
241
242	$is_win = ( 'WIN' === strtoupper( substr( PHP_OS, 0, 3 ) ) );
243
244	if ( ! ( $is_win ? win_is_writable( $dir ) : is_writable( $dir ) ) ) {
245	return false;
246	}
247
248	$count = 0;
249
250	if ( $handle = opendir( $dir ) ) {
251	while ( false !== ( $filename = readdir( $handle ) ) ) {
252	if ( ! preg_match( '/^[0-9]+\.(php\|txt\|png\|gif\|jpeg)$/', $filename ) ) {
253	continue;
254	}
255
256	$file = $this->normalize_path( $dir . $filename );
257	$stat = stat( $file );
258
259	if ( ( $stat['mtime'] + $minutes * 60 ) < time() ) {
260	if ( ! unlink( $file ) ) {
261	chmod( $file, 0644 );
262	unlink( $file );
263	}
264
265	$count += 1;
266	}
267
268	if ( $max <= $count ) {
269	break;
270	}
271	}
272
273	closedir( $handle );
274	}
275
276	return $count;
277	}
278
279	/**
280	* Make a temporary directory and generate .htaccess file in it.
281	*
282	* @return bool True on successful create, false on failure.
283	*/
284	public function make_tmp_dir() {
285	$dir = trailingslashit( $this->tmp_dir );
286	$dir = $this->normalize_path( $dir );
287
288	if ( ! wp_mkdir_p( $dir ) ) {
289	return false;
290	}
291
292	$htaccess_file = $this->normalize_path( $dir . '.htaccess' );
293
294	if ( file_exists( $htaccess_file ) ) {
295	return true;
296	}
297
298	if ( $handle = fopen( $htaccess_file, 'w' ) ) {
299	fwrite( $handle, 'Order deny,allow' . "\n" );
300	fwrite( $handle, 'Deny from all' . "\n" );
301	fwrite( $handle, '<Files ~ "^[0-9A-Za-z]+\\.(jpeg\|gif\|png)$">' . "\n" );
302	fwrite( $handle, ' Allow from all' . "\n" );
303	fwrite( $handle, '</Files>' . "\n" );
304	fclose( $handle );
305	}
306
307	return true;
308	}
309
310	/**
311	* Normalize a filesystem path.
312	*
313	* This should be replaced by wp_normalize_path when the plugin's
314	* minimum requirement becomes WordPress 3.9 or higher.
315	*
316	* @param string $path Path to normalize.
317	* @return string Normalized path.
318	*/
319	private function normalize_path( $path ) {
320	$path = str_replace( '\\', '/', $path );
321	$path = preg_replace( '\|/+\|', '/', $path );
322	return $path;
323	}
324	}
325