AWS API Dlang, hmac sha256 function.

[holo via Digitalmars-d-learn]

I doped HTTP packets with wireshark, maybe that  will  be useful:

First recived:

  Hypertext Transfer Protocol
     HTTP/1.1 400 Bad Request\r\n
         [Expert Info (Chat/Sequence): HTTP/1.1 400 Bad 
Request\r\n]
         Request Version: HTTP/1.1
         Status Code: 400
         Response Phrase: Bad Request
     Transfer-Encoding: chunked\r\n
     Date: Fri, 09 Oct 2015 15:43:37 GMT\r\n
     Cneonction: close\r\n
     Server: AmazonEC2\r\n
     \r\n
     [HTTP response 1/2]
     [Next request in frame: 7739]
     HTTP chunked response

Second sent:

Hypertext Transfer Protocol
     GET /?Action=DescribeInstances&Version=2013-10-15 HTTP/1.1\r\n
         [Expert Info (Chat/Sequence): GET 
/?Action=DescribeInstances&Version=2013-10-15 HTTP/1.1\r\n]
         Request Method: GET
         Request URI: /?Action=DescribeInstances&Version=2013-10-15
         Request Version: HTTP/1.1
     Host:: ec2.amazonaws.com\r\n
     User-Agent: Phobos-std.net.curl/2.069 (libcurl/7.44.0)\r\n
     Accept: */*\r\n
     Content-Type:: application/x-www-form-urlencoded; 
charset=utf-8\r\n
     X-Amz-Date:: 20151009T174337Z\r\n
     Authorization:: AWS4-HMAC-SHA256 
Credential=AKIAIHGPAJQ2PJ47YKKA/20151009T174337Z/us-east-1/ec2/aws4_request, SignedHeaders=content-type;host;x-amz-date, Signature=3049eff7d6b5084c2fee71d10d5cffb17e0df1a9fe76963859c423f637d0496e\r\n
     \r\n
     [Full request URI: http://: 
ec2.amazonaws.com/?Action=DescribeInstances&Version=2013-10-15]
     [HTTP request 2/2]

What is strange why im getting first that 400 Bad Request packet 
and after that is sent GET one?