273 lines
7.4 KiB
Go
273 lines
7.4 KiB
Go
/*
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* Minimal object storage library (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 server
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import (
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"bytes"
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"crypto/hmac"
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"crypto/sha256"
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"encoding/hex"
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"errors"
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"io"
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"io/ioutil"
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"net/http"
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"regexp"
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"sort"
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"strings"
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"time"
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"unicode/utf8"
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)
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const (
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authHeader = "AWS4-HMAC-SHA256"
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iso8601Format = "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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// urlEncodedName encode the strings from UTF-8 byte representations to HTML hex escape sequences
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//
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// This is necessary since regular url.Parse() and url.Encode() functions do not support UTF-8
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// non english characters cannot be parsed due to the nature in which url.Encode() is written
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//
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// This function on the other hand is a direct replacement for url.Encode() technique to support
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// pretty much every UTF-8 character.
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func urlEncodeName(name string) (string, error) {
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// if object matches reserved string, no need to encode them
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reservedNames := regexp.MustCompile("^[a-zA-Z0-9-_.~/]+$")
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if reservedNames.MatchString(name) {
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return name, nil
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}
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var encodedName string
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for _, s := range name {
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if 'A' <= s && s <= 'Z' || 'a' <= s && s <= 'z' || '0' <= s && s <= '9' { // §2.3 Unreserved characters (mark)
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encodedName = encodedName + string(s)
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continue
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}
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switch s {
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case '-', '_', '.', '~', '/': // §2.3 Unreserved characters (mark)
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encodedName = encodedName + string(s)
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continue
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default:
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len := utf8.RuneLen(s)
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if len < 0 {
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return "", errors.New("invalid utf-8")
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}
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u := make([]byte, len)
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utf8.EncodeRune(u, s)
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for _, r := range u {
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hex := hex.EncodeToString([]byte{r})
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encodedName = encodedName + "%" + strings.ToUpper(hex)
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}
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}
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}
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return encodedName, nil
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}
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// sum256Reader calculate sha256 sum for an input read seeker
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func sum256Reader(reader io.ReadSeeker) ([]byte, error) {
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h := sha256.New()
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var err error
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start, _ := reader.Seek(0, 1)
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defer reader.Seek(start, 0)
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for err == nil {
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length := 0
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byteBuffer := make([]byte, 1024*1024)
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length, err = reader.Read(byteBuffer)
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byteBuffer = byteBuffer[0:length]
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h.Write(byteBuffer)
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}
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if err != io.EOF {
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return nil, err
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}
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return h.Sum(nil), nil
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}
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// sum256 calculate sha256 sum for an input byte array
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func sum256(data []byte) []byte {
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hash := sha256.New()
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hash.Write(data)
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return hash.Sum(nil)
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}
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// sumHMAC calculate hmac between two input byte array
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func sumHMAC(key []byte, data []byte) []byte {
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hash := hmac.New(sha256.New, key)
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hash.Write(data)
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return hash.Sum(nil)
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}
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func (s *MyAPISignatureV4Suite) newRequest(method, urlStr string, contentLength int64, body io.ReadSeeker) (*http.Request, error) {
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t := time.Now().UTC()
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req, err := http.NewRequest(method, urlStr, nil)
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if err != nil {
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return nil, err
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}
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req.Header.Set("x-amz-date", t.Format(iso8601Format))
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if method == "" {
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method = "POST"
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}
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// add Content-Length
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req.ContentLength = contentLength
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// add body
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switch {
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case body == nil:
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req.Body = nil
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default:
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req.Body = ioutil.NopCloser(body)
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}
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// save for subsequent use
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hash := func() string {
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switch {
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case body == nil:
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return hex.EncodeToString(sum256([]byte{}))
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default:
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sum256Bytes, _ := sum256Reader(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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req.Header.Set("x-amz-content-sha256", hashedPayload)
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var headers []string
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vals := make(map[string][]string)
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for k, vv := range 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 canonicalHeaders bytes.Buffer
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for _, k := range headers {
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canonicalHeaders.WriteString(k)
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canonicalHeaders.WriteByte(':')
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switch {
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case k == "host":
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canonicalHeaders.WriteString(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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canonicalHeaders.WriteByte(',')
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}
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canonicalHeaders.WriteString(v)
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}
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canonicalHeaders.WriteByte('\n')
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}
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}
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signedHeaders := strings.Join(headers, ";")
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req.URL.RawQuery = strings.Replace(req.URL.Query().Encode(), "+", "%20", -1)
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encodedPath, _ := urlEncodeName(req.URL.Path)
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// convert any space strings back to "+"
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encodedPath = strings.Replace(encodedPath, "+", "%20", -1)
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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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canonicalRequest := strings.Join([]string{
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req.Method,
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encodedPath,
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req.URL.RawQuery,
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canonicalHeaders.String(),
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signedHeaders,
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hashedPayload,
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}, "\n")
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scope := strings.Join([]string{
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t.Format(yyyymmdd),
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"milkyway",
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"s3",
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"aws4_request",
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}, "/")
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stringToSign := authHeader + "\n" + t.Format(iso8601Format) + "\n"
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stringToSign = stringToSign + scope + "\n"
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stringToSign = stringToSign + hex.EncodeToString(sum256([]byte(canonicalRequest)))
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date := sumHMAC([]byte("AWS4"+s.secretAccessKey), []byte(t.Format(yyyymmdd)))
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region := sumHMAC(date, []byte("milkyway"))
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service := sumHMAC(region, []byte("s3"))
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signingKey := sumHMAC(service, []byte("aws4_request"))
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signature := hex.EncodeToString(sumHMAC(signingKey, []byte(stringToSign)))
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// final Authorization header
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parts := []string{
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authHeader + " Credential=" + s.accessKeyID + "/" + scope,
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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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req.Header.Set("Authorization", auth)
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return req, nil
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}
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