tests: Move signature calculation in separate function. (#2160)

Previously newTestRequest() creates request object and returns
signature v4 signed request.  In TestCopyObject(), its required to add
headers later to the request and sign the request.

This patch introduces two new functions
* signRequest(): signs request using given access/secret keys.
* newTestSignedRequest(): returns new request object signed with given
  access/secret keys.

Fixes #2097

test-utils_test.go

@@ -165,20 +165,125 @@ func (testServer TestServer) Stop() {
 	testServer.Server.Close()
 }
 
-// used to formulate HTTP v4 signed HTTP request.
-func newTestRequest(method, urlStr string, contentLength int64, body io.ReadSeeker, accessKey, secretKey string) (*http.Request, error) {
+// Sign given request using Signature V4.
+func signRequest(req *http.Request, accessKey, secretKey string) error {
+	// Get hashed payload.
+	hashedPayload := req.Header.Get("x-amz-content-sha256")
+	if hashedPayload == "" {
+		return fmt.Errorf("Invalid hashed payload.")
+	}
+
+	currTime := time.Now().UTC()
+
+	// Set x-amz-date.
+	req.Header.Set("x-amz-date", currTime.Format(iso8601Format))
+
+	// Get header map.
+	headerMap := make(map[string][]string)
+	for k, vv := range req.Header {
+		// If request header key is not in ignored headers, then add it.
+		if _, ok := ignoredHeaders[http.CanonicalHeaderKey(k)]; !ok {
+			headerMap[strings.ToLower(k)] = vv
+		}
+	}
+
+	// Get header keys.
+	headers := []string{"host"}
+	for k := range headerMap {
+		headers = append(headers, k)
+	}
+	sort.Strings(headers)
+
+	// Get canonical headers.
+	var buf bytes.Buffer
+	for _, k := range headers {
+		buf.WriteString(k)
+		buf.WriteByte(':')
+		switch {
+		case k == "host":
+			buf.WriteString(req.URL.Host)
+			fallthrough
+		default:
+			for idx, v := range headerMap[k] {
+				if idx > 0 {
+					buf.WriteByte(',')
+				}
+				buf.WriteString(v)
+			}
+			buf.WriteByte('\n')
+		}
+	}
+	canonicalHeaders := buf.String()
+
+	// Get signed headers.
+	signedHeaders := strings.Join(headers, ";")
+
+	// Get canonical query string.
+	req.URL.RawQuery = strings.Replace(req.URL.Query().Encode(), "+", "%20", -1)
+
+	// Get canonical URI.
+	canonicalURI := getURLEncodedName(req.URL.Path)
+
+	// Get canonical request.
+	// canonicalRequest =
+	//  <HTTPMethod>\n
+	//  <CanonicalURI>\n
+	//  <CanonicalQueryString>\n
+	//  <CanonicalHeaders>\n
+	//  <SignedHeaders>\n
+	//  <HashedPayload>
+	//
+	canonicalRequest := strings.Join([]string{
+		req.Method,
+		canonicalURI,
+		req.URL.RawQuery,
+		canonicalHeaders,
+		signedHeaders,
+		hashedPayload,
+	}, "\n")
+
+	// Get scope.
+	scope := strings.Join([]string{
+		currTime.Format(yyyymmdd),
+		"us-east-1",
+		"s3",
+		"aws4_request",
+	}, "/")
+
+	stringToSign := "AWS4-HMAC-SHA256" + "\n" + currTime.Format(iso8601Format) + "\n"
+	stringToSign = stringToSign + scope + "\n"
+	stringToSign = stringToSign + hex.EncodeToString(sum256([]byte(canonicalRequest)))
+
+	date := sumHMAC([]byte("AWS4"+secretKey), []byte(currTime.Format(yyyymmdd)))
+	region := sumHMAC(date, []byte("us-east-1"))
+	service := sumHMAC(region, []byte("s3"))
+	signingKey := sumHMAC(service, []byte("aws4_request"))
+
+	signature := hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
+
+	// final Authorization header
+	parts := []string{
+		"AWS4-HMAC-SHA256" + " Credential=" + accessKey + "/" + scope,
+		"SignedHeaders=" + signedHeaders,
+		"Signature=" + signature,
+	}
+	auth := strings.Join(parts, ", ")
+	req.Header.Set("Authorization", auth)
+
+	return nil
+}
+
+// Returns new HTTP request object.
+func newTestRequest(method, urlStr string, contentLength int64, body io.ReadSeeker) (*http.Request, error) {
 	if method == "" {
 		method = "POST"
 	}
-	t := time.Now().UTC()
 
 	req, err := http.NewRequest(method, urlStr, nil)
 	if err != nil {
 		return nil, err
 	}
 
-	req.Header.Set("x-amz-date", t.Format(iso8601Format))
-
 	// Add Content-Length
 	req.ContentLength = contentLength
 
@@ -210,88 +315,20 @@ func newTestRequest(method, urlStr string, contentLength int64, body io.ReadSeek
 		req.Body = ioutil.NopCloser(bytes.NewReader([]byte("")))
 	}
 
-	var headers []string
-	vals := make(map[string][]string)
-	for k, vv := range req.Header {
-		if _, ok := ignoredHeaders[http.CanonicalHeaderKey(k)]; ok {
-			continue // ignored header
-		}
-		headers = append(headers, strings.ToLower(k))
-		vals[strings.ToLower(k)] = vv
-	}
-	headers = append(headers, "host")
-	sort.Strings(headers)
+	return req, nil
+}
 
-	var canonicalHeaders bytes.Buffer
-	for _, k := range headers {
-		canonicalHeaders.WriteString(k)
-		canonicalHeaders.WriteByte(':')
-		switch {
-		case k == "host":
-			canonicalHeaders.WriteString(req.URL.Host)
-			fallthrough
-		default:
-			for idx, v := range vals[k] {
-				if idx > 0 {
-					canonicalHeaders.WriteByte(',')
-				}
-				canonicalHeaders.WriteString(v)
-			}
-			canonicalHeaders.WriteByte('\n')
-		}
+// Returns new HTTP request object signed with signature v4.
+func newTestSignedRequest(method, urlStr string, contentLength int64, body io.ReadSeeker, accessKey, secretKey string) (*http.Request, error) {
+	req, err := newTestRequest(method, urlStr, contentLength, body)
+	if err != nil {
+		return nil, err
 	}
 
-	signedHeaders := strings.Join(headers, ";")
-
-	req.URL.RawQuery = strings.Replace(req.URL.Query().Encode(), "+", "%20", -1)
-	encodedPath := getURLEncodedName(req.URL.Path)
-	// convert any space strings back to "+"
-	encodedPath = strings.Replace(encodedPath, "+", "%20", -1)
-
-	//
-	// canonicalRequest =
-	//  <HTTPMethod>\n
-	//  <CanonicalURI>\n
-	//  <CanonicalQueryString>\n
-	//  <CanonicalHeaders>\n
-	//  <SignedHeaders>\n
-	//  <HashedPayload>
-	//
-	canonicalRequest := strings.Join([]string{
-		req.Method,
-		encodedPath,
-		req.URL.RawQuery,
-		canonicalHeaders.String(),
-		signedHeaders,
-		hashedPayload,
-	}, "\n")
-
-	scope := strings.Join([]string{
-		t.Format(yyyymmdd),
-		"us-east-1",
-		"s3",
-		"aws4_request",
-	}, "/")
-
-	stringToSign := "AWS4-HMAC-SHA256" + "\n" + t.Format(iso8601Format) + "\n"
-	stringToSign = stringToSign + scope + "\n"
-	stringToSign = stringToSign + hex.EncodeToString(sum256([]byte(canonicalRequest)))
-
-	date := sumHMAC([]byte("AWS4"+secretKey), []byte(t.Format(yyyymmdd)))
-	region := sumHMAC(date, []byte("us-east-1"))
-	service := sumHMAC(region, []byte("s3"))
-	signingKey := sumHMAC(service, []byte("aws4_request"))
-
-	signature := hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
-
-	// final Authorization header
-	parts := []string{
-		"AWS4-HMAC-SHA256" + " Credential=" + accessKey + "/" + scope,
-		"SignedHeaders=" + signedHeaders,
-		"Signature=" + signature,
+	err = signRequest(req, accessKey, secretKey)
+	if err != nil {
+		return nil, err
 	}
-	auth := strings.Join(parts, ", ")
-	req.Header.Set("Authorization", auth)
 
 	return req, nil
 }