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

really-simple-captcha.php in Really Simple CAPTCHA 2.1, 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: 2.1
10	*/
11
12	define( 'REALLYSIMPLECAPTCHA_VERSION', '2.1' );
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	$im = imagecreatetruecolor(
111	$this->img_size[0],
112	$this->img_size[1]
113	);
114
115	if ( $im ) {
116	$bg = imagecolorallocate( $im, $this->bg[0], $this->bg[1], $this->bg[2] );
117	$fg = imagecolorallocate( $im, $this->fg[0], $this->fg[1], $this->fg[2] );
118
119	imagefill( $im, 0, 0, $bg );
120
121	$x = $this->base[0] + mt_rand( -2, 2 );
122
123	for ( $i = 0; $i < strlen( $word ); $i++ ) {
124	$font = $this->fonts[array_rand( $this->fonts )];
125	$font = $this->normalize_path( $font );
126
127	imagettftext( $im, $this->font_size, mt_rand( -12, 12 ), $x,
128	$this->base[1] + mt_rand( -2, 2 ), $fg, $font, $word[$i] );
129	$x += $this->font_char_width;
130	}
131
132	switch ( $this->img_type ) {
133	case 'jpeg':
134	$filename = sanitize_file_name( $prefix . '.jpeg' );
135	$file = $this->normalize_path( $dir . $filename );
136	imagejpeg( $im, $file );
137	break;
138	case 'gif':
139	$filename = sanitize_file_name( $prefix . '.gif' );
140	$file = $this->normalize_path( $dir . $filename );
141	imagegif( $im, $file );
142	break;
143	case 'png':
144	default:
145	$filename = sanitize_file_name( $prefix . '.png' );
146	$file = $this->normalize_path( $dir . $filename );
147	imagepng( $im, $file );
148	}
149
150	imagedestroy( $im );
151	@chmod( $file, $this->file_mode );
152	}
153
154	$this->generate_answer_file( $prefix, $word );
155
156	return $filename;
157	}
158
159	/**
160	* Generate answer file corresponding to CAPTCHA image.
161	*
162	* @param string $prefix File prefix used for answer file
163	* @param string $word Random word generated by generate_random_word()
164	*/
165	public function generate_answer_file( $prefix, $word ) {
166	$dir = trailingslashit( $this->tmp_dir );
167	$answer_file = $dir . sanitize_file_name( $prefix . '.txt' );
168	$answer_file = $this->normalize_path( $answer_file );
169
170	if ( $fh = fopen( $answer_file, 'w' ) ) {
171	$word = strtoupper( $word );
172	$salt = wp_generate_password( 64 );
173	$hash = hash_hmac( 'md5', $word, $salt );
174	$code = $salt . '\|' . $hash;
175	fwrite( $fh, $code );
176	fclose( $fh );
177	}
178
179	@chmod( $answer_file, $this->answer_file_mode );
180	}
181
182	/**
183	* Check a response against the code kept in the temporary file.
184	*
185	* @param string $prefix File prefix used for both files
186	* @param string $response CAPTCHA response
187	* @return bool Return true if the two match, otherwise return false.
188	*/
189	public function check( $prefix, $response ) {
190	if ( 0 == strlen( $prefix ) ) {
191	return false;
192	}
193
194	$response = str_replace( array( " ", "\t" ), '', $response );
195	$response = strtoupper( $response );
196
197	$dir = trailingslashit( $this->tmp_dir );
198	$filename = sanitize_file_name( $prefix . '.txt' );
199	$file = $this->normalize_path( $dir . $filename );
200
201	if ( is_readable( $file )
202	and $code = file_get_contents( $file ) ) {
203	$code = explode( '\|', $code, 2 );
204	$salt = $code[0];
205	$hash = $code[1];
206
207	if ( hash_equals( $hash, hash_hmac( 'md5', $response, $salt ) ) ) {
208	return true;
209	}
210	}
211
212	return false;
213	}
214
215	/**
216	* Remove temporary files with given prefix.
217	*
218	* @param string $prefix File prefix
219	*/
220	public function remove( $prefix ) {
221	$dir = trailingslashit( $this->tmp_dir );
222	$suffixes = array( '.jpeg', '.gif', '.png', '.php', '.txt' );
223
224	foreach ( $suffixes as $suffix ) {
225	$filename = sanitize_file_name( $prefix . $suffix );
226	$file = $this->normalize_path( $dir . $filename );
227
228	if ( is_file( $file ) ) {
229	@unlink( $file );
230	}
231	}
232	}
233
234	/**
235	* Clean up dead files older than given length of time.
236	*
237	* @param int $minutes Consider older files than this time as dead files
238	* @return int\|bool The number of removed files. Return false if error occurred.
239	*/
240	public function cleanup( $minutes = 60, $max = 100 ) {
241	$dir = trailingslashit( $this->tmp_dir );
242	$dir = $this->normalize_path( $dir );
243
244	if ( ! is_dir( $dir )
245	or ! is_readable( $dir ) ) {
246	return false;
247	}
248
249	$is_win = ( 'WIN' === strtoupper( substr( PHP_OS, 0, 3 ) ) );
250
251	if ( ! ( $is_win ? win_is_writable( $dir ) : is_writable( $dir ) ) ) {
252	return false;
253	}
254
255	$count = 0;
256
257	if ( $handle = opendir( $dir ) ) {
258	while ( false !== ( $filename = readdir( $handle ) ) ) {
259	if ( ! preg_match( '/^[0-9]+\.(php\|txt\|png\|gif\|jpeg)$/', $filename ) ) {
260	continue;
261	}
262
263	$file = $this->normalize_path( $dir . $filename );
264
265	if ( ! file_exists( $file )
266	or ! $stat = stat( $file ) ) {
267	continue;
268	}
269
270	if ( ( $stat['mtime'] + $minutes * 60 ) < time() ) {
271	if ( ! @unlink( $file ) ) {
272	@chmod( $file, 0644 );
273	@unlink( $file );
274	}
275
276	$count += 1;
277	}
278
279	if ( $max <= $count ) {
280	break;
281	}
282	}
283
284	closedir( $handle );
285	}
286
287	return $count;
288	}
289
290	/**
291	* Make a temporary directory and generate .htaccess file in it.
292	*
293	* @return bool True on successful create, false on failure.
294	*/
295	public function make_tmp_dir() {
296	$dir = trailingslashit( $this->tmp_dir );
297	$dir = $this->normalize_path( $dir );
298
299	if ( ! wp_mkdir_p( $dir ) ) {
300	return false;
301	}
302
303	$htaccess_file = $this->normalize_path( $dir . '.htaccess' );
304
305	if ( file_exists( $htaccess_file ) ) {
306	return true;
307	}
308
309	if ( $handle = fopen( $htaccess_file, 'w' ) ) {
310	fwrite( $handle, 'Order deny,allow' . "\n" );
311	fwrite( $handle, 'Deny from all' . "\n" );
312	fwrite( $handle, '<Files ~ "^[0-9A-Za-z]+\\.(jpeg\|gif\|png)$">' . "\n" );
313	fwrite( $handle, ' Allow from all' . "\n" );
314	fwrite( $handle, '</Files>' . "\n" );
315	fclose( $handle );
316	}
317
318	return true;
319	}
320
321	/**
322	* Normalize a filesystem path.
323	*
324	* This should be replaced by wp_normalize_path when the plugin's
325	* minimum requirement becomes WordPress 3.9 or higher.
326	*
327	* @param string $path Path to normalize.
328	* @return string Normalized path.
329	*/
330	private function normalize_path( $path ) {
331	$path = str_replace( '\\', '/', $path );
332	$path = preg_replace( '\|/+\|', '/', $path );
333	return $path;
334	}
335	}
336