AWS API Dlang, hmac sha256 function.

[holo via Digitalmars-d-learn]

After long fight with previous code i try to rewrite "one-to-one" 
python example from 
http://docs.aws.amazon.com/general/latest/gr/sigv4-signed-request-examples.html (GET part) from begging to D with full success. Here is working code in clear D. Im using hmac function which is available from 2.069 of phobos). It is not too beautiful but like i said im beginner, here it is:


#!/usr/bin/rdmd -L-lcurl

module sigawsv4;

import std.stdio, std.process;
import std.digest.sha, std.digest.hmac;
import std.string;
import std.conv;
import std.datetime;
import std.net.curl;

void main()
{
	auto accessKey = environment["AWS_ACCESS_KEY"];
	auto secretKey = environment["AWS_SECRET_KEY"];

	auto currentClock = Clock.currTime(UTC());

	auto currentDate = cast(Date)currentClock;
	auto curDateStr = currentDate.toISOString;

	auto currentTime = cast(TimeOfDay)currentClock;
	auto curTimeStr = currentTime.toISOString;

	auto xamztime = curDateStr ~ "T" ~ curTimeStr ~ "Z";

	
	string method = "GET";
	string service = "ec2";
	string host = "ec2.amazonaws.com";
	string region = "us-east-1";
	string endpoint = "https://ec2.amazonaws.com";
	string request_parameters = 
"Action=DescribeInstances&Version=2013-10-15";


	auto hmac_sha256(ubyte[] key, ubyte[] msg)
	{
		auto hmac = hmac!SHA256(key);
		hmac.put(msg);
		auto digest = hmac.finish;

		return digest;
	}

	alias sign = hmac_sha256;

	auto getSignatureKey(string key, string dateStamp, string 
regionName, string serviceName)
	{
		ubyte[] kString = cast(ubyte[])("AWS4" ~ key);
		auto kDate = sign(kString, cast(ubyte[])dateStamp);
		auto kRegion = sign(kDate, cast(ubyte[])regionName);
		auto kService = sign(kRegion,  cast(ubyte[])serviceName);
		auto kSigning = sign(kService, cast(ubyte[])"aws4_request");

		return kSigning;
	}


	string canonicalURI = "/";
	string canonicalQueryString = request_parameters;
	string canonicalHeadersString =  "host:" ~ host ~ "\n" ~ 
"x-amz-date:" ~ xamztime ~ "\n";
	string signedHeaders = "host;x-amz-date";
	string payloadHash = sha256Of("").toHexString.toLower;
	string canonicalRequest = method ~ "\n" ~ canonicalURI ~ "\n" ~ 
canonicalQueryString ~ "\n" ~ canonicalHeadersString ~ "\n" ~ 
signedHeaders ~ "\n" ~ payloadHash;


	string algorithm = "AWS4-HMAC-SHA256";
	string credentialScope = curDateStr ~ "/" ~ region ~ "/" ~ 
service ~ "/" ~ "aws4_request";
	string stringToSign = algorithm ~ "\n" ~ xamztime ~ "\n" ~ 
credentialScope ~ "\n" ~ 
sha256Of(canonicalRequest).toHexString.toLower;

	auto signingKey = getSignatureKey(secretKey, curDateStr, region, 
service);

	string signature = hmac_sha256(signingKey, 
cast(ubyte[])stringToSign).toHexString.toLower;

	string authorizationHeader = algorithm ~ " " ~ "Credential=" ~ 
accessKey ~ "/" ~ credentialScope ~ ", " ~ "SignedHeaders=" ~ 
signedHeaders ~ ", " ~ "Signature=" ~ signature;

	auto client = HTTP(endpoint ~ "?" ~ canonicalQueryString);
	client.method = HTTP.Method.get;
	client.addRequestHeader("x-amz-date", xamztime);
	client.addRequestHeader("Authorization", authorizationHeader);
	auto content = client.perform();

	writeln(content);
}

Now will try to "pack" it to some class and make it more usable 
and universal. I think that thread can be closed/solved (if 
something like this exist here)

Thank you all for help.

//holo