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// LICENSE MIT
// Copyright (c) 2018, Rohan Verma <hello@rohanverma.net>
// Copyright (C) 2012 Blake Mizerany
// contains code from: github.com/bmizerany/aws4
package simples3
import (
"bytes"
"crypto/sha256"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"path/filepath"
"sort"
"strings"
"time"
)
func (s3 *S3) signKeys(t time.Time) []byte {
h := makeHMac([]byte("AWS4"+s3.SecretKey), []byte(t.Format(shortTimeFormat)))
h = makeHMac(h, []byte(s3.Region))
h = makeHMac(h, []byte(serviceName))
h = makeHMac(h, []byte("aws4_request"))
return h
}
func (s3 *S3) writeRequest(w io.Writer, r *http.Request) {
r.Header.Set("host", r.Host)
w.Write([]byte(r.Method))
w.Write(newLine)
writeURI(w, r)
w.Write(newLine)
writeQuery(w, r)
w.Write(newLine)
writeHeader(w, r)
w.Write(newLine)
w.Write(newLine)
writeHeaderList(w, r)
w.Write(newLine)
writeBody(w, r)
}
func (s3 *S3) writeStringToSign(w io.Writer, t time.Time, r *http.Request) {
w.Write([]byte(algorithm))
w.Write(newLine)
w.Write([]byte(t.Format(amzDateISO8601TimeFormat)))
w.Write(newLine)
w.Write([]byte(s3.creds(t)))
w.Write(newLine)
h := sha256.New()
s3.writeRequest(h, r)
fmt.Fprintf(w, "%x", h.Sum(nil))
}
func (s3 *S3) creds(t time.Time) string {
return t.Format(shortTimeFormat) + "/" + s3.Region + "/" + serviceName + "/aws4_request"
}
func writeURI(w io.Writer, r *http.Request) {
path := r.URL.RequestURI()
if r.URL.RawQuery != "" {
path = path[:len(path)-len(r.URL.RawQuery)-1]
}
slash := strings.HasSuffix(path, "/")
path = filepath.Clean(path)
if path != "/" && slash {
path += "/"
}
w.Write([]byte(path))
}
func writeQuery(w io.Writer, r *http.Request) {
var a []string
for k, vs := range r.URL.Query() {
k = url.QueryEscape(k)
for _, v := range vs {
if v == "" {
a = append(a, k)
} else {
v = url.QueryEscape(v)
a = append(a, k+"="+v)
}
}
}
sort.Strings(a)
for i, s := range a {
if i > 0 {
w.Write([]byte{'&'})
}
w.Write([]byte(s))
}
}
func writeHeader(w io.Writer, r *http.Request) {
i, a := 0, make([]string, len(r.Header))
for k, v := range r.Header {
sort.Strings(v)
a[i] = strings.ToLower(k) + ":" + strings.Join(v, ",")
i++
}
sort.Strings(a)
for i, s := range a {
if i > 0 {
w.Write(newLine)
}
io.WriteString(w, s)
}
}
func writeHeaderList(w io.Writer, r *http.Request) {
i, a := 0, make([]string, len(r.Header))
for k := range r.Header {
a[i] = strings.ToLower(k)
i++
}
sort.Strings(a)
for i, s := range a {
if i > 0 {
w.Write([]byte{';'})
}
w.Write([]byte(s))
}
}
func writeBody(w io.Writer, r *http.Request) {
var (
b []byte
err error
)
// If the payload is empty, use the empty string as the input to the SHA256 function
// http://docs.amazonwebservices.com/general/latest/gr/sigv4-create-canonical-request.html
if r.Body == nil {
b = []byte("")
} else {
b, err = ioutil.ReadAll(r.Body)
if err != nil {
panic(err)
}
r.Body = ioutil.NopCloser(bytes.NewBuffer(b))
}
h := sha256.New()
h.Write(b)
fmt.Fprintf(w, "%x", h.Sum(nil))
}
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