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<?php
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/**
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* Copyright 2017 Facebook, Inc.
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*
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* You are hereby granted a non-exclusive, worldwide, royalty-free license to
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* use, copy, modify, and distribute this software in source code or binary
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* form for use in connection with the web services and APIs provided by
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* Facebook.
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*
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* As with any software that integrates with the Facebook platform, your use
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* of this software is subject to the Facebook Developer Principles and
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* Policies [http://developers.facebook.com/policy/]. This copyright notice
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* shall be included in all copies or substantial portions of the software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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*
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*/
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/**
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* @see https://github.com/sarciszewski/php-future/blob/master/src/Security.php#L37-L51
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*/
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if (!function_exists('hash_equals')) {
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function hash_equals($knownString, $userString)
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{
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if (function_exists('mb_strlen')) {
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$kLen = mb_strlen($knownString, '8bit');
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$uLen = mb_strlen($userString, '8bit');
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} else {
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$kLen = strlen($knownString);
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$uLen = strlen($userString);
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}
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if ($kLen !== $uLen) {
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return false;
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}
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$result = 0;
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for ($i = 0; $i < $kLen; $i++) {
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$result |= (ord($knownString[$i]) ^ ord($userString[$i]));
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}
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// They are only identical strings if $result is exactly 0...
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return 0 === $result;
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}
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}
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