349 lines
10 KiB
PHP
349 lines
10 KiB
PHP
<?php
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/*
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* Copyright (c) 2014 David Gwynne <david@gwynne.id.au>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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class HttpSignatureError extends Exception { };
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class ExpiredRequestError extends HttpSignatureError { };
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class InvalidHeaderError extends HttpSignatureError { };
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class InvalidParamsError extends HttpSignatureError { };
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class MissingHeaderError extends HttpSignatureError { };
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class InvalidAlgorithmError extends HttpSignatureError { };
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class HTTPSignature {
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static function parse(array $headers, array $options = array())
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{
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if (!array_key_exists('signature', $headers)) {
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throw new MissingHeaderError('no signature header in the request');
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}
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$auth = 'Signature '.$headers['signature'];
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if (!array_key_exists('headers', $options)) {
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$options['headers'] = array(isset($headers['x-date']) ? 'x-date' : 'date');
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} else {
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if (!is_array($options['headers'])) {
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throw new Exception('headers option is not an array');
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}
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if (sizeof(array_filter($options['headers'], function ($a) { return (!is_string($a)); }))) {
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throw new Exception('headers option is not an array of strings');
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}
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}
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if (!array_key_exists('clockSkew', $options)) {
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$options['clockSkew'] = 300;
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} elseif (!is_numeric($options['clockSkew'])) {
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throw new Exception('clockSkew option is not numeric');
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}
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if (array_key_exists('algorithms', $options)) {
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if (!is_array($options['algorithms'])) {
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throw new Exception('algorithms option is not an array');
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}
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if (sizeof(array_filter($options['algorithms'], function ($a) { return (!is_string($a)); }))) {
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throw new Exception('algorithms option is not an array of strings');
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}
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}
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$headers['request-line'] = array_key_exists('requestLine', $options) ?
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$options['requestLine'] :
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sprintf("%s %s %s", $_SERVER['REQUEST_METHOD'], $_SERVER['REQUEST_URI'], $_SERVER['SERVER_PROTOCOL']);
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foreach ($options['headers'] as $header) {
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if (!array_key_exists($header, $headers)) {
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throw new MissingHeaderError("$header was not in the request");
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}
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}
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$states = array(
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'start' => 0,
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'scheme' => 1,
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'space' => 2,
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'param' => 3,
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'quote' => 4,
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'value' => 5,
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'comma' => 6
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);
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$scheme = '';
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$params = array();
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$param = '';
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$value = '';
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$state = $states['start'];
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for ($i = 0; $i < strlen($auth); $i++) {
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$ch = $auth[$i];
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switch ($state) {
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case $states['start']:
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if (ctype_space($ch)) {
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break;
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}
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$state = $states['scheme'];
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/* FALLTHROUGH */
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case $states['scheme']:
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if (ctype_space($ch)) {
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$state = $states['space'];
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} else {
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$scheme .= $ch;
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}
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break;
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case $states['space'];
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if (ctype_space($ch)) {
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continue;
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}
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$state = $states['param'];
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/* FALLTHROUGH */
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case $states['param']:
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if ($ch === '=') {
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if ($param === '') {
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throw new InvalidHeaderError('bad param name');
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}
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if (array_key_exists($param, $params)) {
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throw new InvalidHeaderError('param specified again');
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}
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$state = $states['quote'];
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break;
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}
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if (!ctype_alpha($ch)) {
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throw new InvalidHeaderError('bad param format');
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}
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$param .= $ch;
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break;
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case $states['quote'];
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if ($ch !== '"') {
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throw new InvalidHeaderError('bad param format');
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}
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$state = $states['value'];
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break;
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case $states['value']:
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if ($ch === '"') {
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$params[$param] = $value;
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$param = '';
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$value = '';
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$state = $states['comma'];
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break;
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}
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$value .= $ch;
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break;
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case $states['comma']:
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if ($ch !== ',') {
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throw new InvalidHeaderError('bad param format');
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}
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$state = $states['param'];
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break;
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default:
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throw new Error('invalid state');
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}
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}
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if ($state !== $states['comma']) {
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throw new InvalidHeaderError("bad param format");
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}
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if ($scheme !== 'Signature') {
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throw new InvalidHeaderError('scheme was not "Signature"');
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}
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$required = array('keyId', 'algorithm', 'signature');
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foreach ($required as $param) {
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if (!array_key_exists($param, $params)) {
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throw new InvalidHeaderError("$param was not specified");
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}
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}
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if (array_key_exists('headers', $params)) {
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$params['headers'] = explode(' ', $params['headers']);
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} else {
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$params['headers'] = array(isset($headers['x-date']) ? 'x-date' : 'date');
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}
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foreach ($options['headers'] as $header) {
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if (!in_array($header, $params['headers'])) {
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throw new MissingHeaderError("$header was not a signed header");
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}
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}
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if (isset($options['algorithms']) && !in_array($params['algorithm'], $options['algorithms'])) {
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throw new InvalidParamsError($params['algorithm'] . " is not a supported algorithm");
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}
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$date = null;
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if (isset($headers['date'])) {
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$date = strtotime($headers['date']);
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} elseif (isset($headers['x-date'])) {
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$date = strtotime($headers['x-date']);
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}
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if (!is_null($date)) {
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if ($date === FALSE) {
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throw new InvalidHeaderError('unable to parse date header');
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}
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$skew = abs(time() - $date);
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if ($skew > $options['clockSkew']) {
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throw new ExpiredRequestError(sprintf("clock skew of %ds was greater than %ds", $skew, $options['clockSkew']));
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}
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}
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$sign = array();
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foreach ($params['headers'] as $header) {
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$sign[] = $header === 'request-line' ? $headers['request-line'] : sprintf("%s: %s", $header, $headers[$header]);
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}
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return (array('scheme' => $scheme, 'params' => $params, 'signingString' => implode("\n", $sign)));
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}
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static function verify(array $res, $key, $keytype)
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{
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if (!is_string($key)) {
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throw new Exception('key is not a string');
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}
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$alg = explode('-', $res['params']['algorithm'], 2);
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if (sizeof($alg) != 2) {
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throw new InvalidAlgorithmError("unsupported algorithm");
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}
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if ($alg[0] != $keytype) {
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throw new InvalidAlgorithmError("algorithm type doesn't match key type");
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}
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switch ($alg[0]) {
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case 'rsa':
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$map = array('sha1' => OPENSSL_ALGO_SHA1, 'sha256' => OPENSSL_ALGO_SHA256, 'sha512' => OPENSSL_ALGO_SHA512);
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if (!array_key_exists($alg[1], $map)) {
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throw new InvalidAlgorithmError('unsupported algorithm');
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}
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$pkey = openssl_get_publickey($key);
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if ($pkey === FALSE) {
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throw new Exception('key could not be parsed');
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}
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$rv = openssl_verify($res['signingString'], base64_decode($res['params']['signature']), $pkey, $map[$alg[1]]);
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openssl_free_key($pkey);
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switch ($rv) {
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case 0:
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return (FALSE);
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case 1:
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return (TRUE);
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default:
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throw new Exception('key could not be verified');
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}
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break;
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case 'hmac':
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return (hash_hmac($alg[1], $res['signingString'], $key, true) === base64_decode($res['params']['signature']));
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break;
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default:
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throw new InvalidAlgorithmError("unsupported algorithm");
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}
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}
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static function sign(&$headers = array(), array $options = array())
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{
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if (is_null($headers)) {
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$headers = array();
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} elseif (!is_array($headers)) {
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throw new Exception('headers are not an array');
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}
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if (!array_key_exists('keyId', $options)) {
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throw new Exception('keyId option is missing');
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} elseif (!is_string($options['keyId'])) {
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throw new Exception('keyId option is not a string');
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}
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if (!array_key_exists('key', $options)) {
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throw new Exception('key option is missing');
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} elseif (!is_string($options['key'])) {
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throw new Exception('key option is not a string');
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}
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if (!array_key_exists('headers', $options)) {
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$options['headers'] = array('date');
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} else {
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if (!is_array($options['headers'])) {
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throw new Exception('headers option is not an array');
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}
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if (sizeof(array_filter($options['headers'], function ($a) { return (!is_string($a)); }))) {
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throw new Exception('headers option is not an array of strings');
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}
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}
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if (!array_key_exists('algorithm', $options)) {
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$options['algorithm'] = 'rsa-sha256';
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}
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if (!array_key_exists('date', $headers)) {
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$headers['date'] = date(DATE_RFC1123);
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}
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$headers['request-line'] = array_key_exists('requestLine', $options) ?
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$options['requestLine'] :
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sprintf("%s %s %s", $_SERVER['REQUEST_METHOD'], $_SERVER['REQUEST_URI'], $_SERVER['SERVER_PROTOCOL']);
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$sign = array();
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foreach ($options['headers'] as $header) {
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if (!array_key_exists($header, $headers)) {
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throw new MissingHeaderError("$header was not in the request");
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}
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$sign[] = $header === 'request-line' ? $headers['request-line'] : sprintf("%s: %s", $header, $headers[$header]);
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}
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$data = join("\n", $sign);
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$alg = explode('-', $options['algorithm'], 2);
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if (sizeof($alg) != 2) {
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throw new InvalidAlgorithmError("unsupported algorithm");
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}
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switch ($alg[0]) {
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case 'rsa':
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$map = array('sha1' => OPENSSL_ALGO_SHA1, 'sha256' => OPENSSL_ALGO_SHA256, 'sha512' => OPENSSL_ALGO_SHA512);
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if (!array_key_exists($alg[1], $map)) {
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throw new InvalidAlgorithmError('unsupported algorithm');
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}
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$key = openssl_get_privatekey($options['key']);
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if ($key === FALSE) {
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error_log(openssl_error_string());
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throw new Exception('key option could not be parsed');
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}
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if (openssl_sign($data, $signature, $key, $map[$alg[1]]) === FALSE) {
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throw new Exception('unable to sign');
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}
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break;
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case 'hmac':
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$signature = hash_hmac($alg[1], $data, $options['key'], true);
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break;
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default:
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throw new InvalidAlgorithmError("unsupported algorithm");
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}
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unset($headers['request-line']);
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$headers['authorization'] = sprintf('Signature keyId="%s",algorithm="%s",headers="%s",signature="%s"',
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$options['keyId'], $options['algorithm'], implode(' ', $options['headers']),
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base64_encode($signature));
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}
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}
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