From 41b1c701833334a3da736d21131a9e979366cd1d Mon Sep 17 00:00:00 2001
From: Joe Paul <joeirimpan@gmail.com>
Date: Fri, 7 Dec 2018 11:57:08 +0530
Subject: [PATCH] ref: DRY hmac method (#1)

---
 policy.go |  2 +-
 sign.go   | 35 ++++++++++++++---------------------
 2 files changed, 15 insertions(+), 22 deletions(-)

diff --git a/policy.go b/policy.go
index c70bd8d..4d62bb7 100644
--- a/policy.go
+++ b/policy.go
@@ -59,7 +59,7 @@ var NowTime = func() time.Time {
 	return time.Now()
 }
 
-var lf = []byte{'\n'}
+var newLine = []byte{'\n'}
 
 // CreateUploadPolicies creates amazon s3 sigv4 compatible
 // policy and signing keys with the signature returns the upload policy.
diff --git a/sign.go b/sign.go
index 4d8b57e..e5faf34 100644
--- a/sign.go
+++ b/sign.go
@@ -7,7 +7,6 @@ package simples3
 
 import (
 	"bytes"
-	"crypto/hmac"
 	"crypto/sha256"
 	"fmt"
 	"io"
@@ -21,10 +20,10 @@ import (
 )
 
 func (s3 *S3) signKeys(t time.Time) []byte {
-	h := ghmac([]byte("AWS4"+s3.SecretKey), []byte(t.Format(shortTimeFormat)))
-	h = ghmac(h, []byte(s3.Region))
-	h = ghmac(h, []byte(serviceName))
-	h = ghmac(h, []byte("aws4_request"))
+	h := makeHMac([]byte("AWS4"+s3.SecretKey), []byte(t.Format(shortTimeFormat)))
+	h = makeHMac(h, []byte(s3.Region))
+	h = makeHMac(h, []byte(serviceName))
+	h = makeHMac(h, []byte("aws4_request"))
 	return h
 }
 
@@ -32,27 +31,27 @@ func (s3 *S3) writeRequest(w io.Writer, r *http.Request) {
 	r.Header.Set("host", r.Host)
 
 	w.Write([]byte(r.Method))
-	w.Write(lf)
+	w.Write(newLine)
 	writeURI(w, r)
-	w.Write(lf)
+	w.Write(newLine)
 	writeQuery(w, r)
-	w.Write(lf)
+	w.Write(newLine)
 	writeHeader(w, r)
-	w.Write(lf)
-	w.Write(lf)
+	w.Write(newLine)
+	w.Write(newLine)
 	writeHeaderList(w, r)
-	w.Write(lf)
+	w.Write(newLine)
 	writeBody(w, r)
 }
 
 func (s3 *S3) writeStringToSign(w io.Writer, t time.Time, r *http.Request) {
 	w.Write([]byte("AWS4-HMAC-SHA256"))
-	w.Write(lf)
+	w.Write(newLine)
 	w.Write([]byte(t.Format(amzDateISO8601TimeFormat)))
-	w.Write(lf)
+	w.Write(newLine)
 
 	w.Write([]byte(s3.creds(t)))
-	w.Write(lf)
+	w.Write(newLine)
 
 	h := sha256.New()
 	s3.writeRequest(h, r)
@@ -108,7 +107,7 @@ func writeHeader(w io.Writer, r *http.Request) {
 	sort.Strings(a)
 	for i, s := range a {
 		if i > 0 {
-			w.Write(lf)
+			w.Write(newLine)
 		}
 		io.WriteString(w, s)
 	}
@@ -148,9 +147,3 @@ func writeBody(w io.Writer, r *http.Request) {
 	h.Write(b)
 	fmt.Fprintf(w, "%x", h.Sum(nil))
 }
-
-func ghmac(key, data []byte) []byte {
-	h := hmac.New(sha256.New, key)
-	h.Write(data)
-	return h.Sum(nil)
-}