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

really-simple-captcha.php in Really Simple CAPTCHA 1.9, at really-simple-captcha.php

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1	<?php
2	/*
3	Plugin Name: Really Simple CAPTCHA
4	Plugin URI: http://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: http://ideasilo.wordpress.com/
8	Text Domain: really-simple-captcha
9	Version: 1.9
10	*/
11
12	/* Copyright 2007-2016 Takayuki Miyoshi (email: takayukister at gmail.com)
13
14	This program is free software; you can redistribute it and/or modify
15	it under the terms of the GNU General Public License as published by
16	the Free Software Foundation; either version 2 of the License, or
17	(at your option) any later version.
18
19	This program is distributed in the hope that it will be useful,
20	but WITHOUT ANY WARRANTY; without even the implied warranty of
21	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22	GNU General Public License for more details.
23
24	You should have received a copy of the GNU General Public License
25	along with this program; if not, write to the Free Software
26	Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
27	*/
28
29	define( 'REALLYSIMPLECAPTCHA_VERSION', '1.9' );
30
31	class ReallySimpleCaptcha {
32
33	public function __construct() {
34	/* Characters available in images */
35	$this->chars = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
36
37	/* Length of a word in an image */
38	$this->char_length = 4;
39
40	/* Array of fonts. Randomly picked up per character */
41	$this->fonts = array(
42	dirname( __FILE__ ) . '/gentium/GenBkBasR.ttf',
43	dirname( __FILE__ ) . '/gentium/GenBkBasI.ttf',
44	dirname( __FILE__ ) . '/gentium/GenBkBasBI.ttf',
45	dirname( __FILE__ ) . '/gentium/GenBkBasB.ttf' );
46
47	/* Directory temporary keeping CAPTCHA images and corresponding text files */
48	$this->tmp_dir = path_join( dirname( __FILE__ ), 'tmp' );
49
50	/* Array of CAPTCHA image size. Width and height */
51	$this->img_size = array( 72, 24 );
52
53	/* Background color of CAPTCHA image. RGB color 0-255 */
54	$this->bg = array( 255, 255, 255 );
55
56	/* Foreground (character) color of CAPTCHA image. RGB color 0-255 */
57	$this->fg = array( 0, 0, 0 );
58
59	/* Coordinates for a text in an image. I don't know the meaning. Just adjust. */
60	$this->base = array( 6, 18 );
61
62	/* Font size */
63	$this->font_size = 14;
64
65	/* Width of a character */
66	$this->font_char_width = 15;
67
68	/* Image type. 'png', 'gif' or 'jpeg' */
69	$this->img_type = 'png';
70
71	/* Mode of temporary image files */
72	$this->file_mode = 0644;
73
74	/* Mode of temporary answer text files */
75	$this->answer_file_mode = 0640;
76	}
77
78	/**
79	* Generate and return a random word.
80	*
81	* @return string Random word with $chars characters x $char_length length
82	*/
83	public function generate_random_word() {
84	$word = '';
85
86	for ( $i = 0; $i < $this->char_length; $i++ ) {
87	$pos = mt_rand( 0, strlen( $this->chars ) - 1 );
88	$char = $this->chars[$pos];
89	$word .= $char;
90	}
91
92	return $word;
93	}
94
95	/**
96	* Generate CAPTCHA image and corresponding answer file.
97	*
98	* @param string $prefix File prefix used for both files
99	* @param string $word Random word generated by generate_random_word()
100	* @return string\|bool The file name of the CAPTCHA image. Return false if temp directory is not available.
101	*/
102	public function generate_image( $prefix, $word ) {
103	if ( ! $this->make_tmp_dir() ) {
104	return false;
105	}
106
107	$this->cleanup();
108
109	$dir = trailingslashit( $this->tmp_dir );
110	$filename = null;
111
112	if ( $im = imagecreatetruecolor( $this->img_size[0], $this->img_size[1] ) ) {
113	$bg = imagecolorallocate( $im, $this->bg[0], $this->bg[1], $this->bg[2] );
114	$fg = imagecolorallocate( $im, $this->fg[0], $this->fg[1], $this->fg[2] );
115
116	imagefill( $im, 0, 0, $bg );
117
118	$x = $this->base[0] + mt_rand( -2, 2 );
119
120	for ( $i = 0; $i < strlen( $word ); $i++ ) {
121	$font = $this->fonts[array_rand( $this->fonts )];
122	$font = $this->normalize_path( $font );
123
124	imagettftext( $im, $this->font_size, mt_rand( -12, 12 ), $x,
125	$this->base[1] + mt_rand( -2, 2 ), $fg, $font, $word[$i] );
126	$x += $this->font_char_width;
127	}
128
129	switch ( $this->img_type ) {
130	case 'jpeg':
131	$filename = sanitize_file_name( $prefix . '.jpeg' );
132	$file = $this->normalize_path( $dir . $filename );
133	imagejpeg( $im, $file );
134	break;
135	case 'gif':
136	$filename = sanitize_file_name( $prefix . '.gif' );
137	$file = $this->normalize_path( $dir . $filename );
138	imagegif( $im, $file );
139	break;
140	case 'png':
141	default:
142	$filename = sanitize_file_name( $prefix . '.png' );
143	$file = $this->normalize_path( $dir . $filename );
144	imagepng( $im, $file );
145	}
146
147	imagedestroy( $im );
148	@chmod( $file, $this->file_mode );
149	}
150
151	$this->generate_answer_file( $prefix, $word );
152
153	return $filename;
154	}
155
156	/**
157	* Generate answer file corresponding to CAPTCHA image.
158	*
159	* @param string $prefix File prefix used for answer file
160	* @param string $word Random word generated by generate_random_word()
161	*/
162	public function generate_answer_file( $prefix, $word ) {
163	$dir = trailingslashit( $this->tmp_dir );
164	$answer_file = $dir . sanitize_file_name( $prefix . '.txt' );
165	$answer_file = $this->normalize_path( $answer_file );
166
167	if ( $fh = @fopen( $answer_file, 'w' ) ) {
168	$word = strtoupper( $word );
169	$salt = wp_generate_password( 64 );
170	$hash = hash_hmac( 'md5', $word, $salt );
171
172	$code = $salt . '\|' . $hash;
173
174	fwrite( $fh, $code );
175	fclose( $fh );
176	}
177
178	@chmod( $answer_file, $this->answer_file_mode );
179	}
180
181	/**
182	* Check a response against the code kept in the temporary file.
183	*
184	* @param string $prefix File prefix used for both files
185	* @param string $response CAPTCHA response
186	* @return bool Return true if the two match, otherwise return false.
187	*/
188	public function check( $prefix, $response ) {
189	if ( 0 == strlen( $prefix ) ) {
190	return false;
191	}
192
193	$response = str_replace( array( " ", "\t" ), '', $response );
194	$response = strtoupper( $response );
195
196	$dir = trailingslashit( $this->tmp_dir );
197	$filename = sanitize_file_name( $prefix . '.txt' );
198	$file = $this->normalize_path( $dir . $filename );
199
200	if ( @is_readable( $file ) && ( $code = file_get_contents( $file ) ) ) {
201	$code = explode( '\|', $code, 2 );
202
203	$salt = $code[0];
204	$hash = $code[1];
205
206	if ( hash_hmac( 'md5', $response, $salt ) == $hash ) {
207	return true;
208	}
209	}
210
211	return false;
212	}
213
214	/**
215	* Remove temporary files with given prefix.
216	*
217	* @param string $prefix File prefix
218	*/
219	public function remove( $prefix ) {
220	$dir = trailingslashit( $this->tmp_dir );
221	$suffixes = array( '.jpeg', '.gif', '.png', '.php', '.txt' );
222
223	foreach ( $suffixes as $suffix ) {
224	$filename = sanitize_file_name( $prefix . $suffix );
225	$file = $this->normalize_path( $dir . $filename );
226
227	if ( @is_file( $file ) ) {
228	@unlink( $file );
229	}
230	}
231	}
232
233	/**
234	* Clean up dead files older than given length of time.
235	*
236	* @param int $minutes Consider older files than this time as dead files
237	* @return int\|bool The number of removed files. Return false if error occurred.
238	*/
239	public function cleanup( $minutes = 60, $max = 100 ) {
240	$dir = trailingslashit( $this->tmp_dir );
241	$dir = $this->normalize_path( $dir );
242
243	if ( ! @is_dir( $dir ) \|\| ! @is_readable( $dir ) ) {
244	return false;
245	}
246
247	$is_win = ( 'WIN' === strtoupper( substr( PHP_OS, 0, 3 ) ) );
248
249	if ( ! ( $is_win ? win_is_writable( $dir ) : @is_writable( $dir ) ) ) {
250	return false;
251	}
252
253	$count = 0;
254
255	if ( $handle = @opendir( $dir ) ) {
256	while ( false !== ( $filename = readdir( $handle ) ) ) {
257	if ( ! preg_match( '/^[0-9]+\.(php\|txt\|png\|gif\|jpeg)$/', $filename ) ) {
258	continue;
259	}
260
261	$file = $this->normalize_path( $dir . $filename );
262
263	$stat = @stat( $file );
264	if ( ( $stat['mtime'] + $minutes * 60 ) < time() ) {
265	if ( ! @unlink( $file ) ) {
266	@chmod( $file, 0644 );
267	@unlink( $file );
268	}
269
270	$count += 1;
271	}
272
273	if ( $max <= $count ) {
274	break;
275	}
276	}
277
278	closedir( $handle );
279	}
280
281	return $count;
282	}
283
284	/**
285	* Make a temporary directory and generate .htaccess file in it.
286	*
287	* @return bool True on successful create, false on failure.
288	*/
289	public function make_tmp_dir() {
290	$dir = trailingslashit( $this->tmp_dir );
291	$dir = $this->normalize_path( $dir );
292
293	if ( ! wp_mkdir_p( $dir ) ) {
294	return false;
295	}
296
297	$htaccess_file = $this->normalize_path( $dir . '.htaccess' );
298
299	if ( file_exists( $htaccess_file ) ) {
300	return true;
301	}
302
303	if ( $handle = @fopen( $htaccess_file, 'w' ) ) {
304	fwrite( $handle, 'Order deny,allow' . "\n" );
305	fwrite( $handle, 'Deny from all' . "\n" );
306	fwrite( $handle, '<Files ~ "^[0-9A-Za-z]+\\.(jpeg\|gif\|png)$">' . "\n" );
307	fwrite( $handle, ' Allow from all' . "\n" );
308	fwrite( $handle, '</Files>' . "\n" );
309	fclose( $handle );
310	}
311
312	return true;
313	}
314
315	/**
316	* Normalize a filesystem path.
317	*
318	* This should be replaced by wp_normalize_path when the plugin's
319	* minimum requirement becomes WordPress 3.9 or higher.
320	*
321	* @param string $path Path to normalize.
322	* @return string Normalized path.
323	*/
324	private function normalize_path( $path ) {
325	$path = str_replace( '\\', '/', $path );
326	$path = preg_replace( '\|/+\|', '/', $path );
327	return $path;
328	}
329	}
330