Add x-amz-content-sha256 to CanonicalHeaders

[hanbing0715]

As writing in Signature Calculations for the Authorization Header: Transferring Payload in a Single Chunk (AWS Signature Version 4)

The x-amz-content-sha256 header is required for all AWS Signature Version 4 requests. It provides a hash of the request payload. If there is no payload, you must provide the hash of an empty string.

For the purpose of calculating an authorization signature, only the host and any x-amz-* headers are required;

We should add x-amz-content-sha256 to CanonicalHeaders

[4141done]

Hi @hanbing0715, thank you very much for your contribution. This looks simple but I am going to take some time in the next few days to make sure I fully understand since this is new to me.

[4141done]

Hi @hanbing0715, thank you for your patience. I have been able to test this change and understand the documentation so this looks good! The tests are currently failing because the expected signing key hash does not include this header.

Can you please update your branch with the following change?

diff --git a/test/unit/awssig4_test.js b/test/unit/awssig4_test.js
index 351aed4..b1f3612 100644
--- a/test/unit/awssig4_test.js
+++ b/test/unit/awssig4_test.js
@@ -74,7 +74,7 @@ function _runSignatureV4(r) {
     const canonicalRequest = awssig4._buildCanonicalRequest(r,
         r.method, req.uri, req.queryParams, req.host, amzDatetime, creds.sessionToken);

-    var expected = '600721cacc21e3de14416de7517868381831f4709e5c5663bbf2b738e4d5abe4';
+    var expected = 'cf4dd9e1d28c74e2284f938011efc8230d0c20704f56f67e4a3bfc2212026bec';
     var signature = awssig4._buildSignatureV4(r,
         amzDatetime, eightDigitDate, creds, region, service, canonicalRequest);

Alternately, you could give me permission to push to your branch I can add the small change.

[hanbing0715]

Hello @4141done , I have change the expected result of awssig4, plz rerun the test.

[4141done]

Thank you again for your contribution @hanbing0715 !