Merge pull request aws#365 from aws/v2_signature_headers

Reducing the number of signed sigv4 headers (for v2)

src/Aws/Common/Signature/SignatureV4.php

@@ -19,7 +19,6 @@
 use Aws\Common\Credentials\CredentialsInterface;
 use Aws\Common\Enum\DateFormat;
 use Aws\Common\HostNameUtils;
-use Guzzle\Http\Message\EntityEnclosingRequest;
 use Guzzle\Http\Message\EntityEnclosingRequestInterface;
 use Guzzle\Http\Message\RequestFactory;
 use Guzzle\Http\Message\RequestInterface;
@@ -309,38 +308,34 @@ private function createSigningContext(RequestInterface $request, $payload)
             . $this->createCanonicalizedPath($request) . "\n"
             . $this->getCanonicalizedQueryString($request) . "\n";
 
-        // Create the canonical headers
-        $headers = array();
+        $canonHeaders = array();
+
         foreach ($request->getHeaders()->getAll() as $key => $values) {
             $key = strtolower($key);
-            if ($key != 'user-agent') {
-                $headers[$key] = array();
-                foreach ($values as $value) {
-                    $headers[$key][] = preg_replace('/\s+/', ' ', trim($value));
-                }
-                // Sort the value if there is more than one
-                if (count($values) > 1) {
-                    sort($headers[$key]);
+            if ($key == 'host'
+                || $key == 'date'
+                || substr($key, 0, 6) === 'x-amz-'
+            ) {
+                $values = $values->toArray();
+                if (count($values) == 1) {
+                    $values = $values[0];
+                } else {
+                    sort($values);
+                    $values = implode(',', $values);
                 }
+                $canonHeaders[$key] = $key . ':' . preg_replace('/\s+/', ' ', $values);
             }
         }
 
-        // The headers must be sorted
-        ksort($headers);
-
-        // Continue to build the canonical request by adding headers
-        foreach ($headers as $key => $values) {
-            // Combine multi-value headers into a comma separated list
-            $canon .= $key . ':' . implode(',', $values) . "\n";
-        }
-
-        // Create the signed headers
-        $signedHeaders = implode(';', array_keys($headers));
-        $canon .= "\n{$signedHeaders}\n{$payload}";
+        ksort($canonHeaders);
+        $signedHeadersString = implode(';', array_keys($canonHeaders));
+        $canon .= implode("\n", $canonHeaders) . "\n\n"
+            . $signedHeadersString . "\n"
+            . $payload;
 
         return array(
             'canonical_request' => $canon,
-            'signed_headers'    => $signedHeaders
+            'signed_headers'    => $signedHeadersString
         );
     }