<?php
namespace Aws\Signature;
use Aws\Credentials\CredentialsInterface;
use Aws\Exception\CouldNotCreateChecksumException;
use GuzzleHttp\Psr7;
use Psr\Http\Message\RequestInterface;
/**
* Signature Version 4
* @link http://docs.aws.amazon.com/general/latest/gr/signature-version-4.html
*/
class SignatureV4 implements SignatureInterface
{
const ISO8601_BASIC = 'Ymd\THis\Z';
/** @var string */
private $service;
/** @var string */
private $region;
/** @var array Cache of previously signed values */
private $cache = [];
/** @var int Size of the hash cache */
private $cacheSize = 0;
/**
* @param string $service Service name to use when signing
* @param string $region Region name to use when signing
*/
public function __construct($service, $region)
{
$this->service = $service;
$this->region = $region;
}
public function signRequest(
RequestInterface $request,
CredentialsInterface $credentials
) {
$ldt = gmdate(self::ISO8601_BASIC);
$sdt = substr($ldt, 0, 8);
$parsed = $this->parseRequest($request);
$parsed['headers']['X-Amz-Date'] = [$ldt];
if ($token = $credentials->getSecurityToken()) {
$parsed['headers']['X-Amz-Security-Token'] = [$token];
}
$cs = $this->createScope($sdt, $this->region, $this->service);
$payload = $this->getPayload($request);
$context = $this->createContext($parsed, $payload);
$toSign = $this->createStringToSign($ldt, $cs, $context['creq']);
$signingKey = $this->getSigningKey(
$sdt,
$this->region,
$this->service,
$credentials->getSecretKey()
);
$signature = hash_hmac('sha256', $toSign, $signingKey);
$parsed['headers']['Authorization'] = [
"AWS4-HMAC-SHA256 "
. "Credential={$credentials->getAccessKeyId()}/{$cs}, "
. "SignedHeaders={$context['headers']}, Signature={$signature}"
];
return $this->buildRequest($parsed);
}
public function presign(
RequestInterface $request,
CredentialsInterface $credentials,
$expires
) {
$parsed = $this->createPresignedRequest($request, $credentials);
$payload = $this->getPresignedPayload($request);
$httpDate = gmdate(self::ISO8601_BASIC, time());
$shortDate = substr($httpDate, 0, 8);
$scope = $this->createScope($shortDate, $this->region, $this->service);
$credential = $credentials->getAccessKeyId() . '/' . $scope;
$parsed['query']['X-Amz-Algorithm'] = 'AWS4-HMAC-SHA256';
$parsed['query']['X-Amz-Credential'] = $credential;
$parsed['query']['X-Amz-Date'] = gmdate('Ymd\THis\Z', time());
$parsed['query']['X-Amz-SignedHeaders'] = 'Host';
$parsed['query']['X-Amz-Expires'] = $this->convertExpires($expires);
$context = $this->createContext($parsed, $payload);
$stringToSign = $this->createStringToSign($httpDate, $scope, $context['creq']);
$key = $this->getSigningKey(
$shortDate,
$this->region,
$this->service,
$credentials->getSecretKey()
);
$parsed['query']['X-Amz-Signature'] = hash_hmac('sha256', $stringToSign, $key);
return $this->buildRequest($parsed);
}
/**
* Converts a POST request to a GET request by moving POST fields into the
* query string.
*
* Useful for pre-signing query protocol requests.
*
* @param RequestInterface $request Request to clone
*
* @return RequestInterface
* @throws \InvalidArgumentException if the method is not POST
*/
public static function convertPostToGet(RequestInterface $request)
{
if ($request->getMethod() !== 'POST') {
throw new \InvalidArgumentException('Expected a POST request but '
. 'received a ' . $request->getMethod() . ' request.');
}
$sr = $request->withMethod('GET')
->withBody(Psr7\stream_for(''))
->withoutHeader('Content-Type')
->withoutHeader('Content-Length');
// Move POST fields to the query if they are present
if ($request->getHeaderLine('Content-Type') === 'application/x-www-form-urlencoded') {
$body = (string) $request->getBody();
$sr = $sr->withUri($sr->getUri()->withQuery($body));
}
return $sr;
}
protected function getPayload(RequestInterface $request)
{
// Calculate the request signature payload
if ($request->hasHeader('X-Amz-Content-Sha256')) {
// Handle streaming operations (e.g. Glacier.UploadArchive)
return $request->getHeaderLine('X-Amz-Content-Sha256');
}
if (!$request->getBody()->isSeekable()) {
throw new CouldNotCreateChecksumException('sha256');
}
try {
return Psr7\hash($request->getBody(), 'sha256');
} catch (\Exception $e) {
throw new CouldNotCreateChecksumException('sha256', $e);
}
}
protected function getPresignedPayload(RequestInterface $request)
{
return $this->getPayload($request);
}
protected function createCanonicalizedPath($path)
{
$doubleEncoded = rawurlencode(ltrim($path, '/'));
return '/' . str_replace('%2F', '/', $doubleEncoded);
}
private function createStringToSign($longDate, $credentialScope, $creq)
{
$hash = hash('sha256', $creq);
return "AWS4-HMAC-SHA256\n{$longDate}\n{$credentialScope}\n{$hash}";
}
private function createPresignedRequest(
RequestInterface $request,
CredentialsInterface $credentials
) {
$parsedRequest = $this->parseRequest($request);
// Make sure to handle temporary credentials
if ($token = $credentials->getSecurityToken()) {
$parsedRequest['headers']['X-Amz-Security-Token'] = [$token];
}
return $this->moveHeadersToQuery($parsedRequest);
}
/**
* @param array $parsedRequest
* @param string $payload Hash of the request payload
* @return array Returns an array of context information
*/
private function createContext(array $parsedRequest, $payload)
{
// The following headers are not signed because signing these headers
// would potentially cause a signature mismatch when sending a request
// through a proxy or if modified at the HTTP client level.
static $blacklist = [
'cache-control' => true,
'content-type' => true,
'content-length' => true,
'expect' => true,
'max-forwards' => true,
'pragma' => true,
'range' => true,
'te' => true,
'if-match' => true,
'if-none-match' => true,
'if-modified-since' => true,
'if-unmodified-since' => true,
'if-range' => true,
'accept' => true,
'authorization' => true,
'proxy-authorization' => true,
'from' => true,
'referer' => true,
'user-agent' => true
];
// Normalize the path as required by SigV4
$canon = $parsedRequest['method'] . "\n"
. $this->createCanonicalizedPath($parsedRequest['path']) . "\n"
. $this->getCanonicalizedQuery($parsedRequest['query']) . "\n";
// Case-insensitively aggregate all of the headers.
$aggregate = [];
foreach ($parsedRequest['headers'] as $key => $values) {
$key = strtolower($key);
if (!isset($blacklist[$key])) {
foreach ($values as $v) {
$aggregate[$key][] = $v;
}
}
}
ksort($aggregate);
$canonHeaders = [];
foreach ($aggregate as $k => $v) {
if (count($v) > 0) {
sort($v);
}
$canonHeaders[] = $k . ':' . preg_replace('/\s+/', ' ', implode(',', $v));
}
$signedHeadersString = implode(';', array_keys($aggregate));
$canon .= implode("\n", $canonHeaders) . "\n\n"
. $signedHeadersString . "\n"
. $payload;
return ['creq' => $canon, 'headers' => $signedHeadersString];
}
private function getSigningKey($shortDate, $region, $service, $secretKey)
{
$k = $shortDate . '_' . $region . '_' . $service . '_' . $secretKey;
if (!isset($this->cache[$k])) {
// Clear the cache when it reaches 50 entries
if (++$this->cacheSize > 50) {
$this->cache = [];
$this->cacheSize = 0;
}
$dateKey = hash_hmac('sha256', $shortDate, "AWS4{$secretKey}", true);
$regionKey = hash_hmac('sha256', $region, $dateKey, true);
$serviceKey = hash_hmac('sha256', $service, $regionKey, true);
$this->cache[$k] = hash_hmac('sha256', 'aws4_request', $serviceKey, true);
}
return $this->cache[$k];
}
private function getCanonicalizedQuery(array $query)
{
unset($query['X-Amz-Signature']);
if (!$query) {
return '';
}
$qs = '';
ksort($query);
foreach ($query as $k => $v) {
if (!is_array($v)) {
$qs .= rawurlencode($k) . '=' . rawurlencode($v) . '&';
} else {
sort($v);
foreach ($v as $value) {
$qs .= rawurlencode($k) . '=' . rawurlencode($value) . '&';
}
}
}
return substr($qs, 0, -1);
}
private function convertExpires($expires)
{
if ($expires instanceof \DateTime) {
$expires = $expires->getTimestamp();
} elseif (!is_numeric($expires)) {
$expires = strtotime($expires);
}
$duration = $expires - time();
// Ensure that the duration of the signature is not longer than a week
if ($duration > 604800) {
throw new \InvalidArgumentException('The expiration date of a '
. 'signature version 4 presigned URL must be less than one '
. 'week');
}
return $duration;
}
private function createScope($shortDate, $region, $service)
{
return "$shortDate/$region/$service/aws4_request";
}
private function moveHeadersToQuery(array $parsedRequest)
{
foreach ($parsedRequest['headers'] as $name => $header) {
$lname = strtolower($name);
if (substr($lname, 0, 5) == 'x-amz') {
$parsedRequest['query'][$name] = $header;
}
if ($lname !== 'host') {
unset($parsedRequest['headers'][$name]);
}
}
return $parsedRequest;
}
private function parseRequest(RequestInterface $request)
{
// Clean up any previously set headers.
/** @var RequestInterface $request */
$request = $request
->withoutHeader('X-Amz-Date')
->withoutHeader('Date')
->withoutHeader('Authorization');
$uri = $request->getUri();
return [
'method' => $request->getMethod(),
'path' => $uri->getPath(),
'query' => Psr7\parse_query($uri->getQuery()),
'uri' => $uri,
'headers' => $request->getHeaders(),
'body' => $request->getBody(),
'version' => $request->getProtocolVersion()
];
}
private function buildRequest(array $req)
{
if ($req['query']) {
$req['uri'] = $req['uri']->withQuery(Psr7\build_query($req['query']));
}
return new Psr7\Request(
$req['method'],
$req['uri'],
$req['headers'],
$req['body'],
$req['version']
);
}
}
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