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package paapi5
import (
const (
defaultPartnerType = "Associates"
//Query interface for Client type
type Query interface {
Operation() Operation
Payload() ([]byte, error)
//Client is http.Client for Aozora API Server
type Client struct {
server *Server
client *http.Client
ctx context.Context
partnerTag string
accessKey string
secretKey string
//Marketplace returns name of Marketplace parameter for PA-API v5
func (c *Client) Marketplace() string {
return c.server.Marketplace()
//PartnerTag returns PartnerTag parameter for PA-API v5
func (c *Client) PartnerTag() string {
return c.partnerTag
//PartnerType returns PartnerType parameter for PA-API v5
func (c *Client) PartnerType() string {
return defaultPartnerType
func (c *Client) Request(q Query) ([]byte, error) {
payload, err := q.Payload()
if err != nil {
return nil, errs.Wrap(err, "", errs.WithContext("Operation", q.Operation().String()))
b, err :=, payload)
if err != nil {
return nil, errs.Wrap(err, "", errs.WithContext("Operation", q.Operation().String()), errs.WithContext("payload", string(payload)))
return b, nil
func (c *Client) post(cmd Operation, payload []byte) ([]byte, error) {
dt := NewTimeStamp(time.Now())
u := c.server.URL(cmd.Path())
hds := newHeaders(c.server, cmd, dt)
sig := c.signiture(c.signedString(hds, payload), hds)
req, err := http.NewRequestWithContext(c.ctx, "POST", u.String(), bytes.NewReader(payload))
if err != nil {
return nil, errs.Wrap(err, "", errs.WithContext("url", u.String()), errs.WithContext("payload", string(payload)))
req.Header.Add("Accept", c.server.Accept())
req.Header.Add("Accept-Language", c.server.AcceptLanguage())
req.Header.Add("Content-Type", c.server.ContentType())
req.Header.Add("Content-Encoding", hds.get("Content-Encoding"))
req.Header.Add("Host", hds.get("Host"))
req.Header.Add("X-Amz-Date", hds.get("X-Amz-Date"))
req.Header.Add("X-Amz-Target", hds.get("X-Amz-Target"))
req.Header.Add("Authorization", c.authorization(sig, hds))
resp, err := c.client.Do(req)
if err != nil {
return nil, errs.Wrap(err, "", errs.WithContext("url", u.String()), errs.WithContext("payload", string(payload)))
defer resp.Body.Close()
if !(resp.StatusCode != 0 && resp.StatusCode < http.StatusBadRequest) {
return nil, errs.Wrap(ErrHTTPStatus, "", errs.WithContext("url", u.String()), errs.WithContext("payload", string(payload)), errs.WithContext("status", resp.Status))
body, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, errs.Wrap(err, "", errs.WithContext("url", u.String()), errs.WithContext("payload", string(payload)))
return body, nil
func (c *Client) authorization(sig string, hds *headers) string {
buf := bytes.Buffer{}
buf.WriteString(" Credential=")
buf.WriteString(strings.Join([]string{c.accessKey, hds.dt.StringDate(), c.server.Region(), c.server.ServiceName(), c.server.AWS4Request()}, "/"))
return buf.String()
func (c *Client) signiture(signed string, hds *headers) string {
dateKey := hmacSHA256([]byte("AWS4"+c.secretKey), []byte(hds.dt.StringDate()))
regionKey := hmacSHA256(dateKey, []byte(c.server.Region()))
serviceKey := hmacSHA256(regionKey, []byte(c.server.ServiceName()))
requestKey := hmacSHA256(serviceKey, []byte(c.server.AWS4Request()))
return hex.EncodeToString(hmacSHA256(requestKey, []byte(signed)))
func (c *Client) signedString(hds *headers, payload []byte) string {
return strings.Join(
strings.Join([]string{hds.dt.StringDate(), c.server.Region(), c.server.ServiceName(), c.server.AWS4Request()}, "/"),
hashedString([]byte(c.canonicalRequest(hds, payload))),
func (c *Client) canonicalRequest(hds *headers, payload []byte) string {
request := []string{"POST", hds.cmd.Path(), "", hds.values(), "", hds.list(), hashedString(payload)}
return strings.Join(request, "\n")
func hmacSHA256(key, data []byte) []byte {
hasher := hmac.New(sha256.New, key)
return hasher.Sum(nil)
func hashedString(data []byte) string {
sum := sha256.Sum256(data)
return hex.EncodeToString(sum[:])
type headers struct {
cmd Operation
dt TimeStamp
headers []string
valueList map[string]string
func newHeaders(svr *Server, cmd Operation, dt TimeStamp) *headers {
hds := &headers{cmd: cmd, dt: dt, headers: []string{"content-encoding", "host", "x-amz-date", "x-amz-target"}, valueList: map[string]string{}}
hds.valueList["content-encoding"] = svr.ContentEncoding()
hds.valueList["host"] = svr.HostName()
hds.valueList["x-amz-date"] = dt.String()
hds.valueList["x-amz-target"] = cmd.Target()
return hds
func (h *headers) get(name string) string {
if s, ok := h.valueList[strings.ToLower(name)]; ok {
return s
return ""
func (h *headers) list() string {
return strings.Join(h.headers, ";")
func (h *headers) values() string {
list := []string{}
for _, name := range h.headers {
list = append(list, name+":"+h.get(name))
return strings.Join(list, "\n")
/* Copyright 2019 Spiegel
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
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