fix Context issue

Signed-off-by: Shawn Chen <chen8132@gmail.com>

vendor/github.com/denverdino/aliyungo/cdn/auth/sign_url.go

@@ -0,0 +1,80 @@
+package auth
+
+import (
+	"crypto/md5"
+	"fmt"
+	"net/url"
+	"time"
+)
+
+// An URLSigner provides URL signing utilities to sign URLs for Aliyun CDN
+// resources.
+// authentication document: https://help.aliyun.com/document_detail/85117.html
+type URLSigner struct {
+	authType string
+	privKey  string
+}
+
+// NewURLSigner returns a new signer object.
+func NewURLSigner(authType string, privKey string) *URLSigner {
+	return &URLSigner{
+		authType: authType,
+		privKey:  privKey,
+	}
+}
+
+// Sign returns a signed aliyuncdn url based on authentication type
+func (s URLSigner) Sign(uri string, expires time.Time) (string, error) {
+	r, err := url.Parse(uri)
+	if err != nil {
+		return "", fmt.Errorf("unable to parse url: %s", uri)
+	}
+
+	switch s.authType {
+	case "a":
+		return aTypeSign(r, s.privKey, expires), nil
+	case "b":
+		return bTypeSign(r, s.privKey, expires), nil
+	case "c":
+		return cTypeSign(r, s.privKey, expires), nil
+	default:
+		return "", fmt.Errorf("invalid authentication type")
+	}
+}
+
+// sign by A type authentication method.
+// authentication document: https://help.aliyun.com/document_detail/85113.html
+func aTypeSign(r *url.URL, privateKey string, expires time.Time) string {
+	//rand is a random uuid without "-"
+	rand := GenerateUUID().String()
+	// not use, "0" by default
+	uid := "0"
+	secret := fmt.Sprintf("%s-%d-%s-%s-%s", r.Path, expires.Unix(), rand, uid, privateKey)
+	hashValue := md5.Sum([]byte(secret))
+	authKey := fmt.Sprintf("%d-%s-%s-%x", expires.Unix(), rand, uid, hashValue)
+	if r.RawQuery == "" {
+		return fmt.Sprintf("%s?auth_key=%s", r.String(), authKey)
+	}
+	return fmt.Sprintf("%s&auth_key=%s", r.String(), authKey)
+
+}
+
+// sign by B type authentication method.
+// authentication document: https://help.aliyun.com/document_detail/85114.html
+func bTypeSign(r *url.URL, privateKey string, expires time.Time) string {
+	formatExp := expires.Format("200601021504")
+	secret := privateKey + formatExp + r.Path
+	hashValue := md5.Sum([]byte(secret))
+	signURL := fmt.Sprintf("%s://%s/%s/%x%s?%s", r.Scheme, r.Host, formatExp, hashValue, r.Path, r.RawQuery)
+	return signURL
+}
+
+// sign by C type authentication method.
+// authentication document: https://help.aliyun.com/document_detail/85115.html
+func cTypeSign(r *url.URL, privateKey string, expires time.Time) string {
+	hexExp := fmt.Sprintf("%x", expires.Unix())
+	secret := privateKey + r.Path + hexExp
+	hashValue := md5.Sum([]byte(secret))
+	signURL := fmt.Sprintf("%s://%s/%x/%s%s?%s", r.Scheme, r.Host, hashValue, hexExp, r.Path, r.RawQuery)
+	return signURL
+}