Function PreSignV2

pkg/signer/request-signature-v2.go:60–102

PreSignV2 - presign the request in following style. https://${S3_BUCKET}.s3.amazonaws.com/${S3_OBJECT}?AWSAccessKeyId=${S3_ACCESS_KEY}&Expires=${TIMESTAMP}&Signature=${SIGNATURE}.

(req http.Request, accessKeyID, secretAccessKey string, expires int64, virtualHost bool)

// PreSignV2 - presign the request in following style.
// https://${S3_BUCKET}.s3.amazonaws.com/${S3_OBJECT}?AWSAccessKeyId=${S3_ACCESS_KEY}&Expires=${TIMESTAMP}&Signature=${SIGNATURE}.
func PreSignV2(req http.Request, accessKeyID, secretAccessKey string, expires int64, virtualHost bool) *http.Request {
	// Presign is not needed for anonymous credentials.
	if accessKeyID == "" || secretAccessKey == "" {
		return &req
	}

	d := time.Now().UTC()
	// Find epoch expires when the request will expire.
	epochExpires := d.Unix() + expires

	// Add expires header if not present.
	if expiresStr := req.Header.Get("Expires"); expiresStr == "" {
		req.Header.Set("Expires", strconv.FormatInt(epochExpires, 10))
	}

	// Get presigned string to sign.
	stringToSign := preStringToSignV2(req, virtualHost)
	hm := hmac.New(sha1.New, []byte(secretAccessKey))
	hm.Write([]byte(stringToSign))

	// Calculate signature.
	signature := base64.StdEncoding.EncodeToString(hm.Sum(nil))

	query := req.URL.Query()
	// Handle specially for Google Cloud Storage.
	if strings.Contains(getHostAddr(&req), ".storage.googleapis.com") {
		query.Set("GoogleAccessId", accessKeyID)
	} else {
		query.Set("AWSAccessKeyId", accessKeyID)
	}

	// Fill in Expires for presigned query.
	query.Set("Expires", strconv.FormatInt(epochExpires, 10))

	// Encode query and save.
	req.URL.RawQuery = s3utils.QueryEncode(query)

	// Save signature finally.
	req.URL.RawQuery += "&Signature=" + s3utils.EncodePath(signature)

	// Return.
	return &req
}

// PostPresignSignatureV2 - presigned signature for PostPolicy
// request.