Enable S3 express auth (aws#2839)

Co-authored-by: SamRemis <sjremis94@amazon.com>

.changes/nextrelease/feature-s3express-auth.json

@@ -0,0 +1,7 @@
+[
+  {
+    "type": "feature",
+    "category": "S3",
+    "description": "This release adds support for the S3express identity provider"
+  }
+]

src/AwsClient.php

@@ -445,7 +445,11 @@ private function addSignatureMiddleware()
             return SignatureProvider::resolve($provider, $version, $name, $region);
         };
         $this->handlerList->appendSign(
-            Middleware::signer($this->credentialProvider, $resolver, $this->tokenProvider),
+            Middleware::signer($this->credentialProvider,
+                $resolver,
+                $this->tokenProvider,
+                $this->getConfig()
+            ),
             'signer'
         );
     }

src/Command.php

@@ -77,11 +77,11 @@ public function setAuthSchemes(array $authSchemes)
      * Get auth schemes added to command as required
      * for endpoint resolution
      *
-     * @returns array | null
+     * @returns array
      */
     public function getAuthSchemes()
     {
-        return $this->authSchemes;
+        return $this->authSchemes ?: [];
     }
 
     /** @deprecated */

src/EndpointV2/EndpointV2SerializerTrait.php

@@ -173,7 +173,7 @@ private function applyAuthSchemeToCommand($endpoint, $command)
 
     private function selectAuthScheme($authSchemes)
     {
-        $validAuthSchemes = ['sigv4', 'sigv4a', 'none', 'bearer'];
+        $validAuthSchemes = ['sigv4', 'sigv4a', 'none', 'bearer', 'sigv4-s3express'];
         $invalidAuthSchemes = [];
 
         foreach($authSchemes as $authScheme) {
@@ -204,6 +204,7 @@ private function normalizeAuthScheme($authScheme)
         if (isset($authScheme['disableDoubleEncoding'])
             && $authScheme['disableDoubleEncoding'] === true
             && $authScheme['name'] !== 'sigv4a'
+            && $authScheme['name'] !== 'sigv4-s3express'
         ) {
             $normalizedAuthScheme['version'] = 's3v4';
         } elseif ($authScheme['name'] === 'none') {

src/Identity/S3/S3ExpressIdentity.php

@@ -0,0 +1,6 @@
+<?php
+namespace Aws\Identity\S3;
+
+use Aws\Credentials\Credentials;
+
+class S3ExpressIdentity extends Credentials {}

src/Identity/S3/S3ExpressIdentityProvider.php

@@ -0,0 +1,44 @@
+<?php
+namespace Aws\Identity\S3;
+
+use Aws;
+use Aws\LruArrayCache;
+use GuzzleHttp\Promise;
+
+class S3ExpressIdentityProvider
+{
+
+    private $cache;
+    private $s3Client;
+    public function __construct(string $clientRegion, array $config = [])
+    {
+        $this->cache = new LruArrayCache(100);
+        $this->s3Client = isset($config['client'])
+            ? $config['client'] // internal use only
+            : new Aws\S3\S3Client([
+                'region' => $clientRegion,
+                'disable_express_session_auth' => true
+            ]);
+    }
+
+    public function __invoke($command)
+    {
+        return function () use ($command) {
+            $bucket = $command['Bucket'];
+            if ($identity = $this->cache->get($bucket)) {
+                if (!$identity->isExpired()) {
+                    return Promise\Create::promiseFor($identity);
+                }
+            }
+            $response = $this->s3Client->createSession(['Bucket' => $bucket]);
+            $identity = new Aws\Identity\S3\S3ExpressIdentity(
+                $response['Credentials']['AccessKeyId'],
+                $response['Credentials']['SecretAccessKey'],
+                $response['Credentials']['SessionToken'],
+                $response['Credentials']['Expiration']->getTimestamp()
+            );
+            $this->cache->set($bucket, $identity);
+            return Promise\Create::promiseFor($identity);
+        };
+    }
+}

src/Middleware.php

@@ -6,6 +6,7 @@
 use Aws\Credentials\CredentialsInterface;
 use Aws\EndpointV2\EndpointProviderV2;
 use Aws\Exception\AwsException;
+use Aws\Signature\S3ExpressSignature;
 use Aws\Token\TokenAuthorization;
 use Aws\Token\TokenInterface;
 use GuzzleHttp\Promise;
@@ -125,13 +126,13 @@ public static function requestBuilder(
      *
      * @return callable
      */
-    public static function signer(callable $credProvider, callable $signatureFunction, $tokenProvider = null)
+    public static function signer(callable $credProvider, callable $signatureFunction, $tokenProvider = null, $config = [])
     {
-        return function (callable $handler) use ($signatureFunction, $credProvider, $tokenProvider) {
+        return function (callable $handler) use ($signatureFunction, $credProvider, $tokenProvider, $config) {
             return function (
                 CommandInterface $command,
                 RequestInterface $request
-            ) use ($handler, $signatureFunction, $credProvider, $tokenProvider) {
+            ) use ($handler, $signatureFunction, $credProvider, $tokenProvider, $config) {
                 $signer = $signatureFunction($command);
                 if ($signer instanceof TokenAuthorization) {
                     return $tokenProvider()->then(
@@ -143,17 +144,23 @@ function (TokenInterface $token)
                             );
                         }
                     );
+                }
+
+                if ($signer instanceof S3ExpressSignature) {
+                    $credentialPromise = $config['s3_express_identity_provider']($command)();
                 } else {
-                    return $credProvider()->then(
-                        function (CredentialsInterface $creds)
-                        use ($handler, $command, $signer, $request) {
-                            return $handler(
-                                $command,
-                                $signer->signRequest($request, $creds)
-                            );
-                        }
-                    );
+                    $credentialPromise = $credProvider();
                 }
+
+                return $credentialPromise->then(
+                    function (CredentialsInterface $creds)
+                    use ($handler, $command, $signer, $request) {
+                        return $handler(
+                            $command,
+                            $signer->signRequest($request, $creds)
+                        );
+                    }
+                );
             };
         };
     }

src/S3/ApplyChecksumMiddleware.php

@@ -6,6 +6,7 @@
 use GuzzleHttp\Psr7;
 use InvalidArgumentException;
 use Psr\Http\Message\RequestInterface;
+use Psr\Http\Message\StreamInterface;
 
 /**
  * Apply required or optional checksums to requests before sending.
@@ -79,11 +80,7 @@ public function __invoke(
             if (is_array($supportedAlgorithms)
                 && in_array($requestedAlgorithm, $supportedAlgorithms)
             ) {
-                $headerName = "x-amz-checksum-{$requestedAlgorithm}";
-                $encoded = $this->getEncodedValue($requestedAlgorithm, $body);
-                if (!$request->hasHeader($headerName)) {
-                    $request = $request->withHeader($headerName, $encoded);
-                }
+                $request = $this->addAlgorithmHeader($requestedAlgorithm, $request, $body);
             } else {
                 throw new InvalidArgumentException(
                     "Unsupported algorithm supplied for input variable {$checksumMemberName}."
@@ -99,14 +96,19 @@ public function __invoke(
         $checksumRequired = isset($checksumInfo['requestChecksumRequired'])
             ? $checksumInfo['requestChecksumRequired']
             : null;
-            if ((!empty($checksumRequired) && !$request->hasHeader('Content-MD5'))
+            if ((!empty($checksumRequired))
                 || (in_array($name, self::$sha256AndMd5) && $addContentMD5)
             ) {
-                // Set the content MD5 header for operations that require it.
-                $request = $request->withHeader(
-                    'Content-MD5',
-                    base64_encode(Psr7\Utils::hash($body, 'md5', true))
-                );
+                //S3Express doesn't support MD5; default to crc32 instead
+                if ($this->isS3Express($command)) {
+                    $request = $this->addAlgorithmHeader('crc32', $request, $body);
+                } elseif (!$request->hasHeader('Content-MD5')) {
+                    // Set the content MD5 header for operations that require it.
+                    $request = $request->withHeader(
+                        'Content-MD5',
+                        base64_encode(Psr7\Utils::hash($body, 'md5', true))
+                    );
+                }
                 return $next($command, $request);
             }
         }
@@ -121,4 +123,33 @@ public function __invoke(
 
         return $next($command, $request);
     }
+
+    /**
+     * @param string $requestedAlgorithm
+     * @param RequestInterface $request
+     * @param StreamInterface $body
+     * @return RequestInterface
+     */
+    private function addAlgorithmHeader(
+        string $requestedAlgorithm,
+        RequestInterface $request,
+        StreamInterface $body
+    ) {
+        $headerName = "x-amz-checksum-{$requestedAlgorithm}";
+        if (!$request->hasHeader($headerName)) {
+            $encoded = $this->getEncodedValue($requestedAlgorithm, $body);
+            $request = $request->withHeader($headerName, $encoded);
+        }
+        return $request;
+    }
+
+    /**
+     * @param CommandInterface $command
+     * @return bool
+     */
+    private function isS3Express($command): bool
+    {
+        $authSchemes = $command->getAuthSchemes();
+        return isset($authSchemes['name']) && $authSchemes['name'] == 's3express';
+    }
 }