func getSignature()

in credential.go [26:72]
36 lines of code
7 McCabe index (conditional complexity)

func getSignature(method Method, headers map[string]string, resource, accessKeySecret string) (signature string, err error) {
	signItems := []string{}
	signItems = append(signItems, string(method))

	contentMD5 := ""
	contentType := ""
	date := time.Now().UTC().Format(http.TimeFormat)

	if v, exist := headers[CONTENT_MD5]; exist {
		contentMD5 = v
	}

	if v, exist := headers[CONTENT_TYPE]; exist {
		contentType = v
	}

	if v, exist := headers[DATE]; exist {
		date = v
	}

	mnsHeaders := []string{}

	for k, v := range headers {
		if strings.HasPrefix(k, "x-mns-") {
			mnsHeaders = append(mnsHeaders, k+":"+strings.TrimSpace(v))
		}
	}

	sort.Sort(sort.StringSlice(mnsHeaders))

	stringToSign := string(method) + "\n" +
		contentMD5 + "\n" +
		contentType + "\n" +
		date + "\n" +
		strings.Join(mnsHeaders, "\n") + "\n" +
		resource

	sha1Hash := hmac.New(sha1.New, []byte(accessKeySecret))
	if _, e := sha1Hash.Write([]byte(stringToSign)); e != nil {
		err = ERR_SIGN_MESSAGE_FAILED.New(errors.Params{"err": e})
		return
	}

	signature = base64.StdEncoding.EncodeToString(sha1Hash.Sum(nil))

	return
}