mirror of
https://github.com/octoleo/restic.git
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229 lines
7.0 KiB
Go
229 lines
7.0 KiB
Go
/*
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* Minio Go Library for Amazon S3 Compatible Cloud Storage (C) 2015 Minio, Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package minio
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import (
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"bytes"
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"encoding/hex"
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"errors"
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"net/http"
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"sort"
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"strconv"
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"strings"
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"time"
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)
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const (
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authHeader = "AWS4-HMAC-SHA256"
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iso8601DateFormat = "20060102T150405Z"
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yyyymmdd = "20060102"
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)
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///
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/// Excerpts from @lsegal - https://github.com/aws/aws-sdk-js/issues/659#issuecomment-120477258
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///
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/// User-Agent:
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///
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/// This is ignored from signing because signing this causes problems with generating pre-signed URLs
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/// (that are executed by other agents) or when customers pass requests through proxies, which may
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/// modify the user-agent.
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///
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/// Content-Length:
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///
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/// This is ignored from signing because generating a pre-signed URL should not provide a content-length
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/// constraint, specifically when vending a S3 pre-signed PUT URL. The corollary to this is that when
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/// sending regular requests (non-pre-signed), the signature contains a checksum of the body, which
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/// implicitly validates the payload length (since changing the number of bytes would change the checksum)
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/// and therefore this header is not valuable in the signature.
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///
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/// Content-Type:
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///
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/// Signing this header causes quite a number of problems in browser environments, where browsers
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/// like to modify and normalize the content-type header in different ways. There is more information
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/// on this in https://github.com/aws/aws-sdk-js/issues/244. Avoiding this field simplifies logic
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/// and reduces the possibility of future bugs
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///
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/// Authorization:
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///
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/// Is skipped for obvious reasons
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///
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var ignoredHeaders = map[string]bool{
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"Authorization": true,
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"Content-Type": true,
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"Content-Length": true,
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"User-Agent": true,
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}
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// getHashedPayload get the hexadecimal value of the SHA256 hash of the request payload
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func (r *request) getHashedPayload() string {
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hash := func() string {
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switch {
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case r.expires != 0:
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return "UNSIGNED-PAYLOAD"
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case r.body == nil:
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return hex.EncodeToString(sum256([]byte{}))
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default:
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sum256Bytes, _ := sum256Reader(r.body)
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return hex.EncodeToString(sum256Bytes)
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}
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}
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hashedPayload := hash()
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if hashedPayload != "UNSIGNED-PAYLOAD" {
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r.req.Header.Set("X-Amz-Content-Sha256", hashedPayload)
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}
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return hashedPayload
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}
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// getCanonicalHeaders generate a list of request headers with their values
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func (r *request) getCanonicalHeaders() string {
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var headers []string
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vals := make(map[string][]string)
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for k, vv := range r.req.Header {
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if _, ok := ignoredHeaders[http.CanonicalHeaderKey(k)]; ok {
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continue // ignored header
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}
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headers = append(headers, strings.ToLower(k))
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vals[strings.ToLower(k)] = vv
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}
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headers = append(headers, "host")
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sort.Strings(headers)
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var buf bytes.Buffer
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for _, k := range headers {
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buf.WriteString(k)
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buf.WriteByte(':')
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switch {
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case k == "host":
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buf.WriteString(r.req.URL.Host)
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fallthrough
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default:
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for idx, v := range vals[k] {
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if idx > 0 {
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buf.WriteByte(',')
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}
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buf.WriteString(v)
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}
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buf.WriteByte('\n')
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}
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}
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return buf.String()
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}
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// getSignedHeaders generate a string i.e alphabetically sorted, semicolon-separated list of lowercase request header names
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func (r *request) getSignedHeaders() string {
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var headers []string
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for k := range r.req.Header {
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if _, ok := ignoredHeaders[http.CanonicalHeaderKey(k)]; ok {
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continue // ignored header
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}
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headers = append(headers, strings.ToLower(k))
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}
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headers = append(headers, "host")
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sort.Strings(headers)
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return strings.Join(headers, ";")
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}
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// getCanonicalRequest generate a canonical request of style
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//
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// canonicalRequest =
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// <HTTPMethod>\n
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// <CanonicalURI>\n
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// <CanonicalQueryString>\n
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// <CanonicalHeaders>\n
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// <SignedHeaders>\n
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// <HashedPayload>
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//
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func (r *request) getCanonicalRequest(hashedPayload string) string {
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r.req.URL.RawQuery = strings.Replace(r.req.URL.Query().Encode(), "+", "%20", -1)
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canonicalRequest := strings.Join([]string{
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r.req.Method,
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getURLEncodedPath(r.req.URL.Path),
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r.req.URL.RawQuery,
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r.getCanonicalHeaders(),
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r.getSignedHeaders(),
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hashedPayload,
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}, "\n")
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return canonicalRequest
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}
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// getStringToSign a string based on selected query values
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func (r *request) getStringToSignV4(canonicalRequest string, t time.Time) string {
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stringToSign := authHeader + "\n" + t.Format(iso8601DateFormat) + "\n"
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stringToSign = stringToSign + getScope(r.config.Region, t) + "\n"
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stringToSign = stringToSign + hex.EncodeToString(sum256([]byte(canonicalRequest)))
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return stringToSign
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}
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// Presign the request, in accordance with - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
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func (r *request) PreSignV4() (string, error) {
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if r.config.AccessKeyID == "" && r.config.SecretAccessKey == "" {
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return "", errors.New("presign requires accesskey and secretkey")
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}
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r.SignV4()
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return r.req.URL.String(), nil
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}
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func (r *request) PostPresignSignatureV4(policyBase64 string, t time.Time) string {
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signingkey := getSigningKey(r.config.SecretAccessKey, r.config.Region, t)
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signature := getSignature(signingkey, policyBase64)
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return signature
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}
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// SignV4 the request before Do(), in accordance with - http://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-authenticating-requests.html
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func (r *request) SignV4() {
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query := r.req.URL.Query()
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if r.expires != 0 {
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query.Set("X-Amz-Algorithm", authHeader)
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}
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t := time.Now().UTC()
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// Add date if not present
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if r.expires != 0 {
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query.Set("X-Amz-Date", t.Format(iso8601DateFormat))
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query.Set("X-Amz-Expires", strconv.FormatInt(r.expires, 10))
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} else {
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r.Set("X-Amz-Date", t.Format(iso8601DateFormat))
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}
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hashedPayload := r.getHashedPayload()
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signedHeaders := r.getSignedHeaders()
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if r.expires != 0 {
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query.Set("X-Amz-SignedHeaders", signedHeaders)
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}
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credential := getCredential(r.config.AccessKeyID, r.config.Region, t)
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if r.expires != 0 {
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query.Set("X-Amz-Credential", credential)
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r.req.URL.RawQuery = query.Encode()
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}
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canonicalRequest := r.getCanonicalRequest(hashedPayload)
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stringToSign := r.getStringToSignV4(canonicalRequest, t)
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signingKey := getSigningKey(r.config.SecretAccessKey, r.config.Region, t)
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signature := getSignature(signingKey, stringToSign)
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if r.expires != 0 {
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r.req.URL.RawQuery += "&X-Amz-Signature=" + signature
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} else {
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// final Authorization header
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parts := []string{
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authHeader + " Credential=" + credential,
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"SignedHeaders=" + signedHeaders,
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"Signature=" + signature,
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}
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auth := strings.Join(parts, ", ")
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r.Set("Authorization", auth)
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}
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}
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