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1 | <?php |
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2 | |||
3 | /** |
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4 | * This is a lightweight proxy for serving images, generally meant to be used alongside SSL |
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5 | * |
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6 | * Simple Machines Forum (SMF) |
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7 | * |
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8 | * @package SMF |
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9 | * @author Simple Machines http://www.simplemachines.org |
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10 | * @copyright 2018 Simple Machines and individual contributors |
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11 | * @license http://www.simplemachines.org/about/smf/license.php BSD |
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12 | * |
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13 | * @version 2.1 Beta 4 |
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14 | */ |
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15 | |||
16 | if (!defined('SMF')) |
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17 | define('SMF', 'proxy'); |
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18 | |||
19 | global $proxyhousekeeping; |
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20 | |||
21 | /** |
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22 | * Class ProxyServer |
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23 | */ |
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24 | class ProxyServer |
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25 | { |
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26 | /** @var bool $enabled Whether or not this is enabled */ |
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27 | protected $enabled; |
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28 | |||
29 | /** @var int $maxSize The maximum size for files to cache */ |
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30 | protected $maxSize; |
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31 | |||
32 | /** @var string $secret A secret code used for hashing */ |
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33 | protected $secret; |
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34 | |||
35 | /** @var string The cache directory */ |
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36 | protected $cache; |
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37 | |||
38 | /** @var int $maxDays until enties get deleted */ |
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39 | protected $maxDays; |
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40 | |||
41 | /** |
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42 | * Constructor, loads up the Settings for the proxy |
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43 | * |
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44 | * @access public |
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45 | */ |
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46 | public function __construct() |
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47 | { |
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48 | global $image_proxy_enabled, $image_proxy_maxsize, $image_proxy_secret, $cachedir, $sourcedir; |
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Compatibility
Best Practice
introduced
by
Use of
global functionality is not recommended; it makes your code harder to test, and less reusable.
Instead of relying on 1. Pass all data via parametersfunction myFunction($a, $b) {
// Do something
}
2. Create a class that maintains your stateclass MyClass {
private $a;
private $b;
public function __construct($a, $b) {
$this->a = $a;
$this->b = $b;
}
public function myFunction() {
// Do something
}
}
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49 | |||
50 | require_once(dirname(__FILE__) . '/Settings.php'); |
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51 | require_once($sourcedir . '/Subs.php'); |
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52 | |||
53 | // Turn off all error reporting; any extra junk makes for an invalid image. |
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54 | error_reporting(0); |
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55 | |||
56 | $this->enabled = (bool) $image_proxy_enabled; |
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57 | $this->maxSize = (int) $image_proxy_maxsize; |
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58 | $this->secret = (string) $image_proxy_secret; |
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59 | $this->cache = $cachedir . '/images'; |
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60 | $this->maxDays = 5; |
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61 | } |
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62 | |||
63 | /** |
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64 | * Checks whether the request is valid or not |
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65 | * |
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66 | * @access public |
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67 | * @return bool Whether the request is valid |
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68 | */ |
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69 | public function checkRequest() |
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70 | { |
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71 | if (!$this->enabled) |
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72 | return false; |
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73 | |||
74 | // Try to create the image cache directory if it doesn't exist |
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75 | if (!file_exists($this->cache)) |
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76 | if (!mkdir($this->cache) || !copy(dirname($this->cache) . '/index.php', $this->cache . '/index.php')) |
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77 | return false; |
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78 | |||
79 | // Basic sanity check |
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80 | $_GET['request'] = validate_iri($_GET['request']); |
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81 | |||
82 | // We aren't going anywhere without these |
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83 | if (empty($_GET['hash']) || empty($_GET['request'])) |
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84 | return false; |
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85 | |||
86 | $hash = $_GET['hash']; |
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87 | $request = $_GET['request']; |
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88 | |||
89 | if (md5($request . $this->secret) != $hash) |
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90 | return false; |
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91 | |||
92 | // Ensure any non-ASCII characters in the URL are encoded correctly |
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93 | $request = iri_to_url($request); |
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94 | |||
95 | // Attempt to cache the request if it doesn't exist |
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96 | if (!$this->isCached($request)) |
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It seems like
$request defined by iri_to_url($request) on line 93 can also be of type boolean ; however, ProxyServer::isCached() does only seem to accept string , maybe add an additional type check?
If a method or function can return multiple different values and unless you are sure that you only can receive a single value in this context, we recommend to add an additional type check: /**
* @return array|string
*/
function returnsDifferentValues($x) {
if ($x) {
return 'foo';
}
return array();
}
$x = returnsDifferentValues($y);
if (is_array($x)) {
// $x is an array.
}
If this a common case that PHP Analyzer should handle natively, please let us know by opening an issue. ![]() |
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97 | return $this->cacheImage($request); |
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It seems like
$request defined by iri_to_url($request) on line 93 can also be of type boolean ; however, ProxyServer::cacheImage() does only seem to accept string , maybe add an additional type check?
If a method or function can return multiple different values and unless you are sure that you only can receive a single value in this context, we recommend to add an additional type check: /**
* @return array|string
*/
function returnsDifferentValues($x) {
if ($x) {
return 'foo';
}
return array();
}
$x = returnsDifferentValues($y);
if (is_array($x)) {
// $x is an array.
}
If this a common case that PHP Analyzer should handle natively, please let us know by opening an issue. ![]() |
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98 | |||
99 | return true; |
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100 | } |
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101 | |||
102 | /** |
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103 | * Serves the request |
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104 | * |
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105 | * @access public |
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106 | * @return void |
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107 | */ |
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108 | public function serve() |
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109 | { |
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110 | $request = $_GET['request']; |
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111 | $cached_file = $this->getCachedPath($request); |
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112 | $cached = json_decode(file_get_contents($cached_file), true); |
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113 | |||
114 | // Did we get an error when trying to fetch the image |
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115 | $response = $this->checkRequest(); |
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116 | if ($response === -1) |
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117 | { |
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118 | // Throw a 404 |
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119 | header('HTTP/1.0 404 Not Found'); |
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120 | exit; |
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121 | } |
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122 | // Right, image not cached? Simply redirect, then. |
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123 | if ($response === 0) |
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124 | { |
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125 | $this::redirectexit($request); |
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126 | } |
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127 | |||
128 | $time = time(); |
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129 | |||
130 | // Is the cache expired? |
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131 | if (!$cached || $time - $cached['time'] > ($this->maxDays * 86400)) |
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132 | { |
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133 | @unlink($cached_file); |
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It seems like you do not handle an error condition here. This can introduce security issues, and is generally not recommended.
If you suppress an error, we recommend checking for the error condition explicitly: // For example instead of
@mkdir($dir);
// Better use
if (@mkdir($dir) === false) {
throw new \RuntimeException('The directory '.$dir.' could not be created.');
}
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134 | if ($this->checkRequest()) |
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135 | $this->serve(); |
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136 | $this::redirectexit($request); |
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137 | } |
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138 | |||
139 | $eTag = '"' . substr(sha1($request) . $cached['time'], 0, 64) . '"'; |
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140 | View Code Duplication | if (!empty($_SERVER['HTTP_IF_NONE_MATCH']) && strpos($_SERVER['HTTP_IF_NONE_MATCH'], $eTag) !== false) |
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141 | { |
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142 | header('HTTP/1.1 304 Not Modified'); |
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143 | exit; |
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144 | } |
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145 | |||
146 | // Make sure we're serving an image |
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147 | $contentParts = explode('/', !empty($cached['content_type']) ? $cached['content_type'] : ''); |
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148 | if ($contentParts[0] != 'image') |
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149 | exit; |
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150 | |||
151 | $max_age = $time - $cached['time'] + (5 * 86400); |
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152 | header('content-type: ' . $cached['content_type']); |
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153 | header('content-length: ' . $cached['size']); |
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154 | header('cache-control: public, max-age=' . $max_age ); |
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155 | header('last-modified: ' . gmdate('D, d M Y H:i:s', $cached['time']) . ' GMT'); |
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156 | header('etag: ' . $eTag); |
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157 | echo base64_decode($cached['body']); |
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158 | } |
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159 | |||
160 | /** |
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161 | * Returns the request's hashed filepath |
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162 | * |
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163 | * @access public |
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164 | * @param string $request The request to get the path for |
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165 | * @return string The hashed filepath for the specified request |
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166 | */ |
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167 | protected function getCachedPath($request) |
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168 | { |
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169 | return $this->cache . '/' . sha1($request . $this->secret); |
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170 | } |
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171 | |||
172 | /** |
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173 | * Check whether the image exists in local cache or not |
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174 | * |
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175 | * @access protected |
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176 | * @param string $request The image to check for in the cache |
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177 | * @return bool Whether or not the requested image is cached |
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178 | */ |
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179 | protected function isCached($request) |
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180 | { |
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181 | return file_exists($this->getCachedPath($request)); |
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182 | } |
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183 | |||
184 | /** |
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185 | * Attempts to cache the image while validating it |
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186 | * |
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187 | * @access protected |
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188 | * @param string $request The image to cache/validate |
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189 | * @return int -1 error, 0 too big, 1 valid image |
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190 | */ |
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191 | protected function cacheImage($request) |
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192 | { |
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193 | $dest = $this->getCachedPath($request); |
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194 | $ext = strtolower(pathinfo(parse_url($request, PHP_URL_PATH), PATHINFO_EXTENSION)); |
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195 | |||
196 | $image = fetch_web_data($request); |
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197 | |||
198 | // Looks like nobody was home |
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199 | if (empty($image)) |
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200 | return -1; |
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201 | |||
202 | // What kind of file did they give us? |
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203 | $finfo = finfo_open(FILEINFO_MIME_TYPE); |
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204 | $mime_type = finfo_buffer($finfo, $image); |
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205 | |||
206 | // SVG needs a little extra care |
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207 | if ($ext == 'svg' && $mime_type == 'text/plain') |
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208 | $mime_type = 'image/svg+xml'; |
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209 | |||
210 | // Make sure the url is returning an image |
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211 | if (strpos($mime_type, 'image/') !== 0) |
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212 | return -1; |
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213 | |||
214 | // Validate the filesize |
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215 | $size = strlen($image); |
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216 | if ($size > ($this->maxSize * 1024)) |
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217 | return 0; |
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218 | |||
219 | // Cache it for later |
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220 | return file_put_contents($dest, json_encode(array( |
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221 | 'content_type' => $mime_type, |
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222 | 'size' => $size, |
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223 | 'time' => time(), |
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224 | 'body' => base64_encode($image), |
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225 | ))) === false ? -1 : 1; |
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226 | } |
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227 | |||
228 | /** |
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229 | * Static helper function to redirect a request |
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230 | * |
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231 | * @access public |
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232 | * @param type $request |
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233 | * @return void |
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234 | */ |
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235 | static public function redirectexit($request) |
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236 | { |
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237 | header('Location: ' . $request, false, 301); |
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Security
Response Splitting
introduced
by
'Location: ' . $request can contain request data and is used in response header context(s) leading to a potential security vulnerability.
Response Splitting AttacksAllowing an attacker to set a response header, opens your application to response splitting attacks; effectively allowing an attacker to send any response, he would like. General Strategies to prevent injectionIn general, it is advisable to prevent any user-data to reach this point. This can be done by white-listing certain values:
if ( ! in_array($value, array('this-is-allowed', 'and-this-too'), true)) {
throw new \InvalidArgumentException('This input is not allowed.');
}
For numeric data, we recommend to explicitly cast the data: $sanitized = (integer) $tainted;
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238 | exit; |
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239 | } |
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240 | |||
241 | /** |
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242 | * Delete all old entries |
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243 | * |
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244 | * @access public |
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245 | * @return void |
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246 | */ |
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247 | public function housekeeping() |
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248 | { |
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249 | $path = $this->cache . '/'; |
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250 | if ($handle = opendir($path)) |
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251 | { |
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252 | while (false !== ($file = readdir($handle))) |
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253 | { |
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254 | $filelastmodified = filemtime($path . $file); |
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255 | |||
256 | if ((time() - $filelastmodified) > ($this->maxDays * 86400)) |
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257 | { |
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258 | unlink($path . $file); |
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259 | } |
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260 | } |
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261 | |||
262 | closedir($handle); |
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263 | } |
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264 | } |
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265 | } |
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266 | |||
267 | if (empty($proxyhousekeeping)) |
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268 | { |
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269 | $proxy = new ProxyServer(); |
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270 | $proxy->serve(); |
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271 | } |
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272 | |||
273 | ?> |
Instead of relying on
global
state, we recommend one of these alternatives:1. Pass all data via parameters
2. Create a class that maintains your state