minio/cmd/signature-v4-utils.go

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/*
* Minio Cloud Storage, (C) 2015, 2016, 2017 Minio, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package cmd
import (
"crypto/hmac"
"encoding/hex"
"net/http"
"regexp"
"strconv"
"strings"
"unicode/utf8"
"github.com/minio/sha256-simd"
)
// http Header "x-amz-content-sha256" == "UNSIGNED-PAYLOAD" indicates that the
// client did not calculate sha256 of the payload.
const unsignedPayload = "UNSIGNED-PAYLOAD"
// http Header "x-amz-content-sha256" == "UNSIGNED-PAYLOAD" indicates that the
// client did not calculate sha256 of the payload. Hence we skip calculating sha256.
// We also skip calculating sha256 for presigned requests without "x-amz-content-sha256"
// query header.
func skipContentSha256Cksum(r *http.Request) bool {
queryContentSha256 := r.URL.Query().Get("X-Amz-Content-Sha256")
isRequestPresignedUnsignedPayload := func(r *http.Request) bool {
if isRequestPresignedSignatureV4(r) {
return queryContentSha256 == "" || queryContentSha256 == unsignedPayload
}
return false
}
return isRequestUnsignedPayload(r) || isRequestPresignedUnsignedPayload(r)
}
// Returns SHA256 for calculating canonical-request.
func getContentSha256Cksum(r *http.Request) string {
// For a presigned request we look at the query param for sha256.
if isRequestPresignedSignatureV4(r) {
presignedCkSum := r.URL.Query().Get("X-Amz-Content-Sha256")
if presignedCkSum == "" {
// If not set presigned is defaulted to UNSIGNED-PAYLOAD.
return unsignedPayload
}
return presignedCkSum
}
contentCkSum := r.Header.Get("X-Amz-Content-Sha256")
if contentCkSum == "" {
// If not set content checksum is defaulted to sha256([]byte("")).
contentCkSum = emptySHA256
}
return contentCkSum
}
// isValidRegion - verify if incoming region value is valid with configured Region.
func isValidRegion(reqRegion string, confRegion string) bool {
if confRegion == "" {
return true
}
if confRegion == "US" {
confRegion = globalMinioDefaultRegion
}
// Some older s3 clients set region as "US" instead of
// globalMinioDefaultRegion, handle it.
if reqRegion == "US" {
reqRegion = globalMinioDefaultRegion
}
return reqRegion == confRegion
}
// sumHMAC calculate hmac between two input byte array.
func sumHMAC(key []byte, data []byte) []byte {
hash := hmac.New(sha256.New, key)
hash.Write(data)
return hash.Sum(nil)
}
// Reserved string regexp.
var reservedNames = regexp.MustCompile("^[a-zA-Z0-9-_.~/]+$")
// getURLEncodedName encode the strings from UTF-8 byte representations to HTML hex escape sequences
//
// This is necessary since regular url.Parse() and url.Encode() functions do not support UTF-8
// non english characters cannot be parsed due to the nature in which url.Encode() is written
//
// This function on the other hand is a direct replacement for url.Encode() technique to support
// pretty much every UTF-8 character.
func getURLEncodedName(name string) string {
// if object matches reserved string, no need to encode them
if reservedNames.MatchString(name) {
return name
}
var encodedName string
for _, s := range name {
if 'A' <= s && s <= 'Z' || 'a' <= s && s <= 'z' || '0' <= s && s <= '9' { // §2.3 Unreserved characters (mark)
encodedName = encodedName + string(s)
continue
}
switch s {
case '-', '_', '.', '~', '/': // §2.3 Unreserved characters (mark)
encodedName = encodedName + string(s)
continue
default:
len := utf8.RuneLen(s)
if len > 0 {
u := make([]byte, len)
utf8.EncodeRune(u, s)
for _, r := range u {
hex := hex.EncodeToString([]byte{r})
encodedName = encodedName + "%" + strings.ToUpper(hex)
}
}
}
}
return encodedName
}
// extractSignedHeaders extract signed headers from Authorization header
func extractSignedHeaders(signedHeaders []string, r *http.Request) (http.Header, APIErrorCode) {
reqHeaders := r.Header
// find whether "host" is part of list of signed headers.
// if not return ErrUnsignedHeaders. "host" is mandatory.
if !contains(signedHeaders, "host") {
return nil, ErrUnsignedHeaders
}
extractedSignedHeaders := make(http.Header)
for _, header := range signedHeaders {
// `host` will not be found in the headers, can be found in r.Host.
// but its alway necessary that the list of signed headers containing host in it.
val, ok := reqHeaders[http.CanonicalHeaderKey(header)]
if ok {
for _, enc := range val {
extractedSignedHeaders.Add(header, enc)
}
continue
}
switch header {
case "expect":
// Golang http server strips off 'Expect' header, if the
// client sent this as part of signed headers we need to
// handle otherwise we would see a signature mismatch.
// `aws-cli` sets this as part of signed headers.
//
// According to
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.20
// Expect header is always of form:
//
// Expect = "Expect" ":" 1#expectation
// expectation = "100-continue" | expectation-extension
//
// So it safe to assume that '100-continue' is what would
// be sent, for the time being keep this work around.
// Adding a *TODO* to remove this later when Golang server
// doesn't filter out the 'Expect' header.
extractedSignedHeaders.Set(header, "100-continue")
case "host":
// Go http server removes "host" from Request.Header
extractedSignedHeaders.Set(header, r.Host)
case "transfer-encoding":
// Go http server removes "host" from Request.Header
for _, enc := range r.TransferEncoding {
extractedSignedHeaders.Add(header, enc)
}
case "content-length":
// Signature-V4 spec excludes Content-Length from signed headers list for signature calculation.
// But some clients deviate from this rule. Hence we consider Content-Length for signature
// calculation to be compatible with such clients.
extractedSignedHeaders.Set(header, strconv.FormatInt(r.ContentLength, 10))
default:
return nil, ErrUnsignedHeaders
}
}
return extractedSignedHeaders, ErrNone
}
// Trim leading and trailing spaces and replace sequential spaces with one space, following Trimall()
// in http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
func signV4TrimAll(input string) string {
// Compress adjacent spaces (a space is determined by
// unicode.IsSpace() internally here) to one space and return
return strings.Join(strings.Fields(input), " ")
}