pkg/etag: add new package for S3 ETag handling (#11577)

This commit adds a new package `etag` for dealing
with S3 ETags.

Even though ETag is often viewed as MD5 checksum of
an object, handling S3 ETags correctly is a surprisingly
complex task. While it is true that the ETag corresponds
to the MD5 for the most basic S3 API operations, there are
many exceptions in case of multipart uploads or encryption.

In worse, some S3 clients expect very specific behavior when
it comes to ETags. For example, some clients expect that the
ETag is a double-quoted string and fail otherwise.
Non-AWS compliant ETag handling has been a source of many bugs
in the past.

Therefore, this commit adds a dedicated `etag` package that provides
functionality for parsing, generating and converting S3 ETags.
Further, this commit removes the ETag computation from the `hash`
package. Instead, the `hash` package (i.e. `hash.Reader`) should
focus only on computing and verifying the content-sha256.

One core feature of this commit is to provide a mechanism to
communicate a computed ETag from a low-level `io.Reader` to
a high-level `io.Reader`.

This problem occurs when an S3 server receives a request and
has to compute the ETag of the content. However, the server
may also wrap the initial body with several other `io.Reader`,
e.g. when encrypting or compressing the content:
```
   reader := Encrypt(Compress(ETag(content)))
```
In such a case, the ETag should be accessible by the high-level
`io.Reader`.

The `etag` provides a mechanism to wrap `io.Reader` implementations
such that the `ETag` can be accessed by a type-check.
This technique is applied to the PUT, COPY and Upload handlers.
This commit is contained in:
Andreas Auernhammer 2021-02-23 21:31:53 +01:00 committed by GitHub
parent 1b63291ee2
commit d4b822d697
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
19 changed files with 821 additions and 234 deletions

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@ -459,8 +459,7 @@ func isReqAuthenticated(ctx context.Context, r *http.Request, region string, sty
// Verify 'Content-Md5' and/or 'X-Amz-Content-Sha256' if present.
// The verification happens implicit during reading.
reader, err := hash.NewReader(r.Body, -1, hex.EncodeToString(contentMD5),
hex.EncodeToString(contentSHA256), -1, globalCLIContext.StrictS3Compat)
reader, err := hash.NewReader(r.Body, -1, hex.EncodeToString(contentMD5), hex.EncodeToString(contentSHA256), -1)
if err != nil {
return toAPIErrorCode(ctx, err)
}

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@ -917,7 +917,7 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
return
}
hashReader, err := hash.NewReader(fileBody, fileSize, "", "", fileSize, globalCLIContext.StrictS3Compat)
hashReader, err := hash.NewReader(fileBody, fileSize, "", "", fileSize)
if err != nil {
logger.LogIf(ctx, err)
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
@ -964,7 +964,7 @@ func (api objectAPIHandlers) PostPolicyBucketHandler(w http.ResponseWriter, r *h
}
info := ObjectInfo{Size: fileSize}
// do not try to verify encrypted content
hashReader, err = hash.NewReader(reader, info.EncryptedSize(), "", "", fileSize, globalCLIContext.StrictS3Compat)
hashReader, err = hash.NewReader(reader, info.EncryptedSize(), "", "", fileSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return

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@ -692,7 +692,7 @@ func restoreTransitionedObject(ctx context.Context, bucket, object string, objAP
return err
}
defer gr.Close()
hashReader, err := hash.NewReader(gr, objInfo.Size, "", "", objInfo.Size, globalCLIContext.StrictS3Compat)
hashReader, err := hash.NewReader(gr, objInfo.Size, "", "", objInfo.Size)
if err != nil {
return err
}

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@ -64,7 +64,7 @@ func deleteConfig(ctx context.Context, objAPI objectDeleter, configFile string)
}
func saveConfig(ctx context.Context, objAPI ObjectLayer, configFile string, data []byte) error {
hashReader, err := hash.NewReader(bytes.NewReader(data), int64(len(data)), "", getSHA256Hash(data), int64(len(data)), globalCLIContext.StrictS3Compat)
hashReader, err := hash.NewReader(bytes.NewReader(data), int64(len(data)), "", getSHA256Hash(data), int64(len(data)))
if err != nil {
return err
}

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@ -128,7 +128,7 @@ func runDataScanner(ctx context.Context, objAPI ObjectLayer) {
nextBloomCycle++
var tmp [8]byte
binary.LittleEndian.PutUint64(tmp[:], nextBloomCycle)
r, err := hash.NewReader(bytes.NewReader(tmp[:]), int64(len(tmp)), "", "", int64(len(tmp)), false)
r, err := hash.NewReader(bytes.NewReader(tmp[:]), int64(len(tmp)), "", "", int64(len(tmp)))
if err != nil {
logger.LogIf(ctx, err)
continue

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@ -513,7 +513,7 @@ func (d *dataUsageCache) save(ctx context.Context, store objectIO, name string)
}()
defer pr.Close()
r, err := hash.NewReader(pr, -1, "", "", -1, false)
r, err := hash.NewReader(pr, -1, "", "", -1)
if err != nil {
return err
}

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@ -47,7 +47,7 @@ func storeDataUsageInBackend(ctx context.Context, objAPI ObjectLayer, dui <-chan
continue
}
size := int64(len(dataUsageJSON))
r, err := hash.NewReader(bytes.NewReader(dataUsageJSON), size, "", "", size, false)
r, err := hash.NewReader(bytes.NewReader(dataUsageJSON), size, "", "", size)
if err != nil {
logger.LogIf(ctx, err)
continue

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@ -705,7 +705,7 @@ func (c *cacheObjects) uploadObject(ctx context.Context, oi ObjectInfo) {
if st == CommitComplete || st.String() == "" {
return
}
hashReader, err := hash.NewReader(cReader, oi.Size, "", "", oi.Size, globalCLIContext.StrictS3Compat)
hashReader, err := hash.NewReader(cReader, oi.Size, "", "", oi.Size)
if err != nil {
return
}

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@ -168,7 +168,7 @@ func getGWMetadata(ctx context.Context, bucket, prefix string, gwMeta gwMetaV1)
logger.LogIf(ctx, err)
return nil, err
}
hashReader, err := hash.NewReader(bytes.NewReader(metadataBytes), int64(len(metadataBytes)), "", "", int64(len(metadataBytes)), false)
hashReader, err := hash.NewReader(bytes.NewReader(metadataBytes), int64(len(metadataBytes)), "", "", int64(len(metadataBytes)))
if err != nil {
return nil, err
}

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@ -176,7 +176,7 @@ func (b *bucketMetacache) save(ctx context.Context) error {
b.updated = false
b.mu.Unlock()
hr, err := hash.NewReader(tmp, int64(tmp.Len()), "", "", int64(tmp.Len()), false)
hr, err := hash.NewReader(tmp, int64(tmp.Len()), "", "", int64(tmp.Len()))
if err != nil {
return err
}

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@ -672,7 +672,7 @@ func (er *erasureObjects) listPath(ctx context.Context, o listPathOptions) (entr
return nil
}
o.debugln(color.Green("listPath:")+" saving block", b.n, "to", o.objectPath(b.n))
r, err := hash.NewReader(bytes.NewReader(b.data), int64(len(b.data)), "", "", int64(len(b.data)), false)
r, err := hash.NewReader(bytes.NewReader(b.data), int64(len(b.data)), "", "", int64(len(b.data)))
logger.LogIf(ctx, err)
custom := b.headerKV()
_, err = er.putObject(ctx, minioMetaBucket, o.objectPath(b.n), NewPutObjReader(r), ObjectOptions{

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@ -48,6 +48,7 @@ import (
objectlock "github.com/minio/minio/pkg/bucket/object/lock"
"github.com/minio/minio/pkg/bucket/policy"
"github.com/minio/minio/pkg/bucket/replication"
"github.com/minio/minio/pkg/etag"
"github.com/minio/minio/pkg/event"
"github.com/minio/minio/pkg/handlers"
"github.com/minio/minio/pkg/hash"
@ -1025,7 +1026,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
srcInfo.metadataOnly = false
}
var reader io.Reader
var reader io.Reader = gr
// Set the actual size to the compressed/decrypted size if encrypted.
actualSize, err := srcInfo.GetActualSize()
@ -1057,15 +1058,15 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
// avoid copying them in target object.
crypto.RemoveInternalEntries(srcInfo.UserDefined)
s2c := newS2CompressReader(gr, actualSize)
s2c := newS2CompressReader(reader, actualSize)
defer s2c.Close()
reader = s2c
reader = etag.Wrap(s2c, reader)
length = -1
} else {
reader = gr
}
srcInfo.Reader, err = hash.NewReader(reader, length, "", "", actualSize, globalCLIContext.StrictS3Compat)
srcInfo.Reader, err = hash.NewReader(reader, length, "", "", actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -1162,11 +1163,13 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
}
if isTargetEncrypted {
reader, objEncKey, err = newEncryptReader(srcInfo.Reader, newKey, dstBucket, dstObject, encMetadata, sseS3)
var encReader io.Reader
encReader, objEncKey, err = newEncryptReader(srcInfo.Reader, newKey, dstBucket, dstObject, encMetadata, sseS3)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
}
reader = etag.Wrap(encReader, srcInfo.Reader)
}
if isSourceEncrypted {
@ -1176,7 +1179,7 @@ func (api objectAPIHandlers) CopyObjectHandler(w http.ResponseWriter, r *http.Re
}
// do not try to verify encrypted content
srcInfo.Reader, err = hash.NewReader(reader, targetSize, "", "", actualSize, globalCLIContext.StrictS3Compat)
srcInfo.Reader, err = hash.NewReader(reader, targetSize, "", "", actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -1457,13 +1460,12 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
}
var (
md5hex = hex.EncodeToString(md5Bytes)
sha256hex = ""
reader io.Reader
md5hex = hex.EncodeToString(md5Bytes)
sha256hex = ""
reader io.Reader = r.Body
s3Err APIErrorCode
putObject = objectAPI.PutObject
)
reader = r.Body
// Check if put is allowed
if s3Err = isPutActionAllowed(ctx, rAuthType, bucket, object, r, iampolicy.PutObjectAction); s3Err != ErrNone {
@ -1509,13 +1511,12 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
}
actualSize := size
if objectAPI.IsCompressionSupported() && isCompressible(r.Header, object) && size > 0 {
// Storing the compression metadata.
metadata[ReservedMetadataPrefix+"compression"] = compressionAlgorithmV2
metadata[ReservedMetadataPrefix+"actual-size"] = strconv.FormatInt(size, 10)
actualReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize, globalCLIContext.StrictS3Compat)
actualReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -1524,13 +1525,13 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
// Set compression metrics.
s2c := newS2CompressReader(actualReader, actualSize)
defer s2c.Close()
reader = s2c
reader = etag.Wrap(s2c, actualReader)
size = -1 // Since compressed size is un-predictable.
md5hex = "" // Do not try to verify the content.
sha256hex = ""
}
hashReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize, globalCLIContext.StrictS3Compat)
hashReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -1601,7 +1602,7 @@ func (api objectAPIHandlers) PutObjectHandler(w http.ResponseWriter, r *http.Req
}
// do not try to verify encrypted content
hashReader, err = hash.NewReader(reader, wantSize, "", "", actualSize, globalCLIContext.StrictS3Compat)
hashReader, err = hash.NewReader(etag.Wrap(reader, hashReader), wantSize, "", "", actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -1999,8 +2000,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
return
}
partInfo, err := core.PutObjectPart(ctx, dstBucket, dstObject, uploadID, partID,
gr, length, "", "", dstOpts.ServerSideEncryption)
partInfo, err := core.PutObjectPart(ctx, dstBucket, dstObject, uploadID, partID, gr, length, "", "", dstOpts.ServerSideEncryption)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -2015,7 +2015,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
}
actualPartSize = length
var reader io.Reader
var reader io.Reader = etag.NewReader(gr, nil)
mi, err := objectAPI.GetMultipartInfo(ctx, dstBucket, dstObject, uploadID, dstOpts)
if err != nil {
@ -2027,15 +2027,13 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
_, isCompressed := mi.UserDefined[ReservedMetadataPrefix+"compression"]
// Compress only if the compression is enabled during initial multipart.
if isCompressed {
s2c := newS2CompressReader(gr, actualPartSize)
s2c := newS2CompressReader(reader, actualPartSize)
defer s2c.Close()
reader = s2c
reader = etag.Wrap(s2c, reader)
length = -1
} else {
reader = gr
}
srcInfo.Reader, err = hash.NewReader(reader, length, "", "", actualPartSize, globalCLIContext.StrictS3Compat)
srcInfo.Reader, err = hash.NewReader(reader, length, "", "", actualPartSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -2077,11 +2075,12 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
copy(objectEncryptionKey[:], key)
partEncryptionKey := objectEncryptionKey.DerivePartKey(uint32(partID))
reader, err = sio.EncryptReader(reader, sio.Config{Key: partEncryptionKey[:]})
encReader, err := sio.EncryptReader(reader, sio.Config{Key: partEncryptionKey[:]})
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
}
reader = etag.Wrap(encReader, reader)
wantSize := int64(-1)
if length >= 0 {
@ -2089,7 +2088,7 @@ func (api objectAPIHandlers) CopyObjectPartHandler(w http.ResponseWriter, r *htt
wantSize = info.EncryptedSize()
}
srcInfo.Reader, err = hash.NewReader(reader, wantSize, "", "", actualPartSize, globalCLIContext.StrictS3Compat)
srcInfo.Reader, err = hash.NewReader(reader, wantSize, "", "", actualPartSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -2209,12 +2208,11 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
}
var (
md5hex = hex.EncodeToString(md5Bytes)
sha256hex = ""
reader io.Reader
md5hex = hex.EncodeToString(md5Bytes)
sha256hex = ""
reader io.Reader = r.Body
s3Error APIErrorCode
)
reader = r.Body
if s3Error = isPutActionAllowed(ctx, rAuthType, bucket, object, r, iampolicy.PutObjectAction); s3Error != ErrNone {
writeErrorResponse(ctx, w, errorCodes.ToAPIErr(s3Error), r.URL, guessIsBrowserReq(r))
return
@ -2271,7 +2269,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
_, isCompressed := mi.UserDefined[ReservedMetadataPrefix+"compression"]
if objectAPI.IsCompressionSupported() && isCompressed {
actualReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize, globalCLIContext.StrictS3Compat)
actualReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -2280,13 +2278,13 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
// Set compression metrics.
s2c := newS2CompressReader(actualReader, actualSize)
defer s2c.Close()
reader = s2c
reader = etag.Wrap(s2c, actualReader)
size = -1 // Since compressed size is un-predictable.
md5hex = "" // Do not try to verify the content.
sha256hex = ""
}
hashReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize, globalCLIContext.StrictS3Compat)
hashReader, err := hash.NewReader(reader, size, md5hex, sha256hex, actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
@ -2343,7 +2341,7 @@ func (api objectAPIHandlers) PutObjectPartHandler(w http.ResponseWriter, r *http
wantSize = info.EncryptedSize()
}
// do not try to verify encrypted content
hashReader, err = hash.NewReader(reader, wantSize, "", "", actualSize, globalCLIContext.StrictS3Compat)
hashReader, err = hash.NewReader(etag.Wrap(reader, hashReader), wantSize, "", "", actualSize)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return

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@ -160,7 +160,7 @@ func calculateSignedChunkLength(chunkDataSize int64) int64 {
}
func mustGetPutObjReader(t TestErrHandler, data io.Reader, size int64, md5hex, sha256hex string) *PutObjReader {
hr, err := hash.NewReader(data, size, md5hex, sha256hex, size, globalCLIContext.StrictS3Compat)
hr, err := hash.NewReader(data, size, md5hex, sha256hex, size)
if err != nil {
t.Fatal(err)
}

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@ -50,6 +50,7 @@ import (
objectlock "github.com/minio/minio/pkg/bucket/object/lock"
"github.com/minio/minio/pkg/bucket/policy"
"github.com/minio/minio/pkg/bucket/replication"
"github.com/minio/minio/pkg/etag"
"github.com/minio/minio/pkg/event"
"github.com/minio/minio/pkg/handlers"
"github.com/minio/minio/pkg/hash"
@ -1233,7 +1234,7 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
var reader io.Reader = r.Body
actualSize := size
hashReader, err := hash.NewReader(reader, size, "", "", actualSize, globalCLIContext.StrictS3Compat)
hashReader, err := hash.NewReader(reader, size, "", "", actualSize)
if err != nil {
writeWebErrorResponse(w, err)
return
@ -1244,7 +1245,7 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
metadata[ReservedMetadataPrefix+"compression"] = compressionAlgorithmV2
metadata[ReservedMetadataPrefix+"actual-size"] = strconv.FormatInt(actualSize, 10)
actualReader, err := hash.NewReader(reader, actualSize, "", "", actualSize, globalCLIContext.StrictS3Compat)
actualReader, err := hash.NewReader(reader, actualSize, "", "", actualSize)
if err != nil {
writeWebErrorResponse(w, err)
return
@ -1254,8 +1255,8 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
size = -1 // Since compressed size is un-predictable.
s2c := newS2CompressReader(actualReader, actualSize)
defer s2c.Close()
reader = s2c
hashReader, err = hash.NewReader(reader, size, "", "", actualSize, globalCLIContext.StrictS3Compat)
reader = etag.Wrap(s2c, actualReader)
hashReader, err = hash.NewReader(reader, size, "", "", actualSize)
if err != nil {
writeWebErrorResponse(w, err)
return
@ -1276,15 +1277,18 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
if objectAPI.IsEncryptionSupported() {
if _, ok := crypto.IsRequested(r.Header); ok && !HasSuffix(object, SlashSeparator) { // handle SSE requests
var objectEncryptionKey crypto.ObjectKey
reader, objectEncryptionKey, err = EncryptRequest(hashReader, r, bucket, object, metadata)
var (
objectEncryptionKey crypto.ObjectKey
encReader io.Reader
)
encReader, objectEncryptionKey, err = EncryptRequest(hashReader, r, bucket, object, metadata)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return
}
info := ObjectInfo{Size: size}
// do not try to verify encrypted content
hashReader, err = hash.NewReader(reader, info.EncryptedSize(), "", "", size, globalCLIContext.StrictS3Compat)
hashReader, err = hash.NewReader(etag.Wrap(encReader, hashReader), info.EncryptedSize(), "", "", size)
if err != nil {
writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL, guessIsBrowserReq(r))
return

284
pkg/etag/etag.go Normal file
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@ -0,0 +1,284 @@
// MinIO Cloud Storage, (C) 2021 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 etag provides an implementation of S3 ETags.
//
// Each S3 object has an associated ETag that can be
// used to e.g. quickly compare objects or check whether
// the content of an object has changed.
//
// In general, an S3 ETag is an MD5 checksum of the object
// content. However, there are many exceptions to this rule.
//
//
// Single-part Upload
//
// In case of a basic single-part PUT operation - without server
// side encryption or object compression - the ETag of an object
// is its content MD5.
//
//
// Multi-part Upload
//
// The ETag of an object does not correspond to its content MD5
// when the object is uploaded in multiple parts via the S3
// multipart API. Instead, S3 first computes a MD5 of each part:
// e1 := MD5(part-1)
// e2 := MD5(part-2)
// ...
// eN := MD5(part-N)
//
// Then, the ETag of the object is computed as MD5 of all individual
// part checksums. S3 also encodes the number of parts into the ETag
// by appending a -<number-of-parts> at the end:
// ETag := MD5(e1 || e2 || e3 ... || eN) || -N
//
// For example: ceb8853ddc5086cc4ab9e149f8f09c88-5
//
// However, this scheme is only used for multipart objects that are
// not encrypted.
//
// Server-side Encryption
//
// S3 specifies three types of server-side-encryption - SSE-C, SSE-S3
// and SSE-KMS - with different semantics w.r.t. ETags.
// In case of SSE-S3, the ETag of an object is computed the same as
// for single resp. multipart plaintext objects. In particular,
// the ETag of a singlepart SSE-S3 object is its content MD5.
//
// In case of SSE-C and SSE-KMS, the ETag of an object is computed
// differently. For singlepart uploads the ETag is not the content
// MD5 of the object. For multipart uploads the ETag is also not
// the MD5 of the individual part checksums but it still contains
// the number of parts as suffix.
//
// Instead, the ETag is kind of unpredictable for S3 clients when
// an object is encrypted using SSE-C or SSE-KMS. Maybe AWS S3
// computes the ETag as MD5 of the encrypted content but there is
// no way to verify this assumption since the encryption happens
// inside AWS S3.
// Therefore, S3 clients must not make any assumption about ETags
// in case of SSE-C or SSE-KMS except that the ETag is well-formed.
//
// To put all of this into a simple rule:
// SSE-S3 : ETag == MD5
// SSE-C : ETag != MD5
// SSE-KMS: ETag != MD5
//
//
// Encrypted ETags
//
// An S3 implementation has to remember the content MD5 of objects
// in case of SSE-S3. However, storing the ETag of an encrypted
// object in plaintext may reveal some information about the object.
// For example, two objects with the same ETag are identical with
// a very high probability.
//
// Therefore, an S3 implementation may encrypt an ETag before storing
// it. In this case, the stored ETag may not be a well-formed S3 ETag.
// For example, it can be larger due to a checksum added by authenticated
// encryption schemes. Such an ETag must be decrypted before sent to an
// S3 client.
//
//
// S3 Clients
//
// There are many different S3 client implementations. Most of them
// access the ETag by looking for the HTTP response header key "Etag".
// However, some of them assume that the header key has to be "ETag"
// (case-sensitive) and will fail otherwise.
// Further, some clients require that the ETag value is a double-quoted
// string. Therefore, this package provides dedicated functions for
// adding and extracing the ETag to/from HTTP headers.
package etag
import (
"bytes"
"encoding/hex"
"errors"
"fmt"
"net/http"
"strconv"
"strings"
)
// ETag is a single S3 ETag.
//
// An S3 ETag sometimes corresponds to the MD5 of
// the S3 object content. However, when an object
// is encrypted, compressed or uploaded using
// the S3 multipart API then its ETag is not
// necessarily the MD5 of the object content.
//
// For a more detailed description of S3 ETags
// take a look at the package documentation.
type ETag []byte
// String returns the string representation of the ETag.
//
// The returned string is a hex representation of the
// binary ETag with an optional '-<part-number>' suffix.
func (e ETag) String() string {
if e.IsMultipart() {
return hex.EncodeToString(e[:16]) + string(e[16:])
}
return hex.EncodeToString(e)
}
// IsEncrypted reports whether the ETag is encrypted.
func (e ETag) IsEncrypted() bool {
return len(e) > 16 && !bytes.ContainsRune(e, '-')
}
// IsMultipart reports whether the ETag belongs to an
// object that has been uploaded using the S3 multipart
// API.
// An S3 multipart ETag has a -<part-number> suffix.
func (e ETag) IsMultipart() bool {
return len(e) > 16 && bytes.ContainsRune(e, '-')
}
// Parts returns the number of object parts that are
// referenced by this ETag. It returns 1 if the object
// has been uploaded using the S3 singlepart API.
//
// Parts may panic if the ETag is an invalid multipart
// ETag.
func (e ETag) Parts() int {
if !e.IsMultipart() {
return 1
}
n := bytes.IndexRune(e, '-')
parts, err := strconv.Atoi(string(e[n+1:]))
if err != nil {
panic(err) // malformed ETag
}
return parts
}
var _ Tagger = ETag{} // compiler check
// ETag returns the ETag itself.
//
// By providing this method ETag implements
// the Tagger interface.
func (e ETag) ETag() ETag { return e }
// Set adds the ETag to the HTTP headers. It overwrites any
// existing ETag entry.
//
// Due to legacy S3 clients, that make incorrect assumptions
// about HTTP headers, Set should be used instead of
// http.Header.Set(...). Otherwise, some S3 clients will not
// able to extract the ETag.
func Set(etag ETag, h http.Header) {
// Some (broken) S3 clients expect the ETag header to
// literally "ETag" - not "Etag". Further, some clients
// expect an ETag in double quotes. Therefore, we set the
// ETag directly as map entry instead of using http.Header.Set
h["ETag"] = []string{`"` + etag.String() + `"`}
}
// Get extracts and parses an ETag from the given HTTP headers.
// It returns an error when the HTTP headers do not contain
// an ETag entry or when the ETag is malformed.
//
// Get only accepts AWS S3 compatible ETags - i.e. no
// encrypted ETags - and therefore is stricter than Parse.
func Get(h http.Header) (ETag, error) {
const strict = true
if v := h.Get("Etag"); v != "" {
return parse(v, strict)
}
v, ok := h["ETag"]
if !ok || len(v) == 0 {
return nil, errors.New("etag: HTTP header does not contain an ETag")
}
return parse(v[0], strict)
}
// Equal returns true if and only if the two ETags are
// identical.
func Equal(a, b ETag) bool { return bytes.Equal(a, b) }
// Parse parses s as an S3 ETag, returning the result.
// The string can be an encrypted, singlepart
// or multipart S3 ETag. It returns an error if s is
// not a valid textual representation of an ETag.
func Parse(s string) (ETag, error) {
const strict = false
return parse(s, strict)
}
// parse parse s as an S3 ETag, returning the result.
// It operates in one of two modes:
// - strict
// - non-strict
//
// In strict mode, parse only accepts ETags that
// are AWS S3 compatible. In particular, an AWS
// S3 ETag always consists of a 128 bit checksum
// value and an optional -<part-number> suffix.
// Therefore, s must have the following form in
// strict mode: <32-hex-characters>[-<integer>]
//
// In non-strict mode, parse also accepts ETags
// that are not AWS S3 compatible - e.g. encrypted
// ETags.
func parse(s string, strict bool) (ETag, error) {
// An S3 ETag may be a double-quoted string.
// Therefore, we remove double quotes at the
// start and end, if any.
if strings.HasPrefix(s, `"`) && strings.HasSuffix(s, `"`) {
s = s[1 : len(s)-1]
}
// An S3 ETag may be a multipart ETag that
// contains a '-' followed by a number.
// If the ETag does not a '-' is is either
// a singlepart or encrypted ETag.
n := strings.IndexRune(s, '-')
if n == -1 {
etag, err := hex.DecodeString(s)
if err != nil {
return nil, err
}
if strict && len(etag) != 16 { // AWS S3 ETags are always 128 bit long
return nil, fmt.Errorf("etag: invalid length %d", len(etag))
}
return ETag(etag), nil
}
prefix, suffix := s[:n], s[n:]
if len(prefix) != 32 {
return nil, fmt.Errorf("etag: invalid prefix length %d", len(prefix))
}
if len(suffix) <= 1 {
return nil, errors.New("etag: suffix is not a part number")
}
etag, err := hex.DecodeString(prefix)
if err != nil {
return nil, err
}
partNumber, err := strconv.Atoi(suffix[1:]) // suffix[0] == '-' Therefore, we start parsing at suffix[1]
if err != nil {
return nil, err
}
if strict && (partNumber == 0 || partNumber > 10000) {
return nil, fmt.Errorf("etag: invalid part number %d", partNumber)
}
return ETag(append(etag, suffix...)), nil
}

139
pkg/etag/etag_test.go Normal file
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@ -0,0 +1,139 @@
// MinIO Cloud Storage, (C) 2021 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 etag
import (
"io"
"io/ioutil"
"strings"
"testing"
)
var parseTests = []struct {
String string
ETag ETag
ShouldFail bool
}{
{String: "3b83ef96387f1465", ETag: ETag{59, 131, 239, 150, 56, 127, 20, 101}}, // 0
{String: "3b83ef96387f14655fc854ddc3c6bd57", ETag: ETag{59, 131, 239, 150, 56, 127, 20, 101, 95, 200, 84, 221, 195, 198, 189, 87}}, // 1
{String: `"3b83ef96387f14655fc854ddc3c6bd57"`, ETag: ETag{59, 131, 239, 150, 56, 127, 20, 101, 95, 200, 84, 221, 195, 198, 189, 87}}, // 2
{String: "ceb8853ddc5086cc4ab9e149f8f09c88-1", ETag: ETag{206, 184, 133, 61, 220, 80, 134, 204, 74, 185, 225, 73, 248, 240, 156, 136, 45, 49}}, // 3
{String: `"ceb8853ddc5086cc4ab9e149f8f09c88-2"`, ETag: ETag{206, 184, 133, 61, 220, 80, 134, 204, 74, 185, 225, 73, 248, 240, 156, 136, 45, 50}}, // 4
{ // 5
String: "90402c78d2dccddee1e9e86222ce2c6361675f3529d26000ae2e900ff216b3cb59e130e092d8a2981e776f4d0bd60941",
ETag: ETag{144, 64, 44, 120, 210, 220, 205, 222, 225, 233, 232, 98, 34, 206, 44, 99, 97, 103, 95, 53, 41, 210, 96, 0, 174, 46, 144, 15, 242, 22, 179, 203, 89, 225, 48, 224, 146, 216, 162, 152, 30, 119, 111, 77, 11, 214, 9, 65},
},
{String: `"3b83ef96387f14655fc854ddc3c6bd57`, ShouldFail: true}, // 6
{String: "ceb8853ddc5086cc4ab9e149f8f09c88-", ShouldFail: true}, // 7
{String: "ceb8853ddc5086cc4ab9e149f8f09c88-2a", ShouldFail: true}, // 8
{String: "ceb8853ddc5086cc4ab9e149f8f09c88-2-1", ShouldFail: true}, // 9
{String: "90402c78d2dccddee1e9e86222ce2c-1", ShouldFail: true}, // 10
{String: "90402c78d2dccddee1e9e86222ce2c6361675f3529d26000ae2e900ff216b3cb59e130e092d8a2981e776f4d0bd60941-1", ShouldFail: true}, // 11
}
func TestParse(t *testing.T) {
for i, test := range parseTests {
etag, err := Parse(test.String)
if err == nil && test.ShouldFail {
t.Fatalf("Test %d: parse should have failed but succeeded", i)
}
if err != nil && !test.ShouldFail {
t.Fatalf("Test %d: failed to parse ETag %q: %v", i, test.String, err)
}
if !Equal(etag, test.ETag) {
t.Log([]byte(etag))
t.Fatalf("Test %d: ETags don't match", i)
}
}
}
var stringTests = []struct {
ETag ETag
String string
}{
{ETag: ETag{59, 131, 239, 150, 56, 127, 20, 101}, String: "3b83ef96387f1465"}, // 0
{ETag: ETag{59, 131, 239, 150, 56, 127, 20, 101, 95, 200, 84, 221, 195, 198, 189, 87}, String: "3b83ef96387f14655fc854ddc3c6bd57"}, // 1
{ETag: ETag{206, 184, 133, 61, 220, 80, 134, 204, 74, 185, 225, 73, 248, 240, 156, 136, 45, 49}, String: "ceb8853ddc5086cc4ab9e149f8f09c88-1"}, // 2
{ETag: ETag{206, 184, 133, 61, 220, 80, 134, 204, 74, 185, 225, 73, 248, 240, 156, 136, 45, 50}, String: "ceb8853ddc5086cc4ab9e149f8f09c88-2"}, // 3
{ // 4
ETag: ETag{144, 64, 44, 120, 210, 220, 205, 222, 225, 233, 232, 98, 34, 206, 44, 99, 97, 103, 95, 53, 41, 210, 96, 0, 174, 46, 144, 15, 242, 22, 179, 203, 89, 225, 48, 224, 146, 216, 162, 152, 30, 119, 111, 77, 11, 214, 9, 65},
String: "90402c78d2dccddee1e9e86222ce2c6361675f3529d26000ae2e900ff216b3cb59e130e092d8a2981e776f4d0bd60941",
},
}
func TestString(t *testing.T) {
for i, test := range stringTests {
s := test.ETag.String()
if s != test.String {
t.Fatalf("Test %d: got %s - want %s", i, s, test.String)
}
}
}
var equalTests = []struct {
A string
B string
Equal bool
}{
{A: "3b83ef96387f14655fc854ddc3c6bd57", B: "3b83ef96387f14655fc854ddc3c6bd57", Equal: true}, // 0
{A: "3b83ef96387f14655fc854ddc3c6bd57", B: `"3b83ef96387f14655fc854ddc3c6bd57"`, Equal: true}, // 1
{A: "3b83ef96387f14655fc854ddc3c6bd57", B: "3b83ef96387f14655fc854ddc3c6bd57-2", Equal: false}, // 2
{A: "3b83ef96387f14655fc854ddc3c6bd57", B: "ceb8853ddc5086cc4ab9e149f8f09c88", Equal: false}, // 3
}
func TestEqual(t *testing.T) {
for i, test := range equalTests {
A, err := Parse(test.A)
if err != nil {
t.Fatalf("Test %d: %v", i, err)
}
B, err := Parse(test.B)
if err != nil {
t.Fatalf("Test %d: %v", i, err)
}
if equal := Equal(A, B); equal != test.Equal {
t.Fatalf("Test %d: got %v - want %v", i, equal, test.Equal)
}
}
}
var readerTests = []struct { // Reference values computed by: echo <content> | md5sum
Content string
ETag ETag
}{
{
Content: "", ETag: ETag{212, 29, 140, 217, 143, 0, 178, 4, 233, 128, 9, 152, 236, 248, 66, 126},
},
{
Content: " ", ETag: ETag{114, 21, 238, 156, 125, 157, 194, 41, 210, 146, 26, 64, 232, 153, 236, 95},
},
{
Content: "Hello World", ETag: ETag{177, 10, 141, 177, 100, 224, 117, 65, 5, 183, 169, 155, 231, 46, 63, 229},
},
}
func TestReader(t *testing.T) {
for i, test := range readerTests {
reader := NewReader(strings.NewReader(test.Content), test.ETag)
if _, err := io.Copy(ioutil.Discard, reader); err != nil {
t.Fatalf("Test %d: read failed: %v", i, err)
}
if ETag := reader.ETag(); !Equal(ETag, test.ETag) {
t.Fatalf("Test %d: ETag mismatch: got %q - want %q", i, ETag, test.ETag)
}
}
}

151
pkg/etag/reader.go Normal file
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@ -0,0 +1,151 @@
// MinIO Cloud Storage, (C) 2021 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 etag
import (
"crypto/md5"
"fmt"
"hash"
"io"
)
// Tagger is the interface that wraps the basic ETag method.
type Tagger interface {
ETag() ETag
}
type wrapReader struct {
io.Reader
Tagger
}
// ETag returns the ETag of the underlying Tagger.
func (r *wrapReader) ETag() ETag {
if r.Tagger == nil {
return nil
}
return r.Tagger.ETag()
}
// Wrap returns an io.Reader that reads from the wrapped
// io.Reader and implements the Tagger interaface.
//
// If content implements Tagger then the returned Reader
// returns ETag of the content. Otherwise, it returns
// nil as ETag.
//
// Wrap provides an adapter for io.Reader implemetations
// that don't implement the Tagger interface.
// It is mainly used to provide a high-level io.Reader
// access to the ETag computed by a low-level io.Reader:
//
// content := etag.NewReader(r.Body, nil)
//
// compressedContent := Compress(content)
// encryptedContent := Encrypt(compressedContent)
//
// // Now, we need an io.Reader that can access
// // the ETag computed over the content.
// reader := etag.Wrap(encryptedContent, content)
//
func Wrap(wrapped, content io.Reader) io.Reader {
if t, ok := content.(Tagger); ok {
return wrapReader{
Reader: wrapped,
Tagger: t,
}
}
return wrapReader{
Reader: wrapped,
}
}
// A Reader wraps an io.Reader and computes the
// MD5 checksum of the read content as ETag.
//
// Optionally, a Reader can also verify that
// the computed ETag matches an expected value.
// Therefore, it compares both ETags once the
// underlying io.Reader returns io.EOF.
// If the computed ETag does not match the
// expected ETag then Read returns a VerifyError.
//
// Reader implements the Tagger interface.
type Reader struct {
src io.Reader
md5 hash.Hash
checksum ETag
readN int64
}
// NewReader returns a new Reader that computes the
// MD5 checksum of the content read from r as ETag.
//
// If the provided etag is not nil the returned
// Reader compares the etag with the computed
// MD5 sum once the r returns io.EOF.
func NewReader(r io.Reader, etag ETag) *Reader {
if er, ok := r.(*Reader); ok {
if er.readN == 0 && Equal(etag, er.checksum) {
return er
}
}
return &Reader{
src: r,
md5: md5.New(),
checksum: etag,
}
}
// Read reads up to len(p) bytes from the underlying
// io.Reader as specified by the io.Reader interface.
func (r *Reader) Read(p []byte) (int, error) {
n, err := r.src.Read(p)
r.readN += int64(n)
r.md5.Write(p[:n])
if err == io.EOF && len(r.checksum) != 0 {
if etag := r.ETag(); !Equal(etag, r.checksum) {
return n, VerifyError{
Expected: r.checksum,
Computed: etag,
}
}
}
return n, err
}
// ETag returns the ETag of all the content read
// so far. Reading more content changes the MD5
// checksum. Therefore, calling ETag multiple
// times may return different results.
func (r *Reader) ETag() ETag {
sum := r.md5.Sum(nil)
return ETag(sum)
}
// VerifyError is an error signaling that a
// computed ETag does not match an expected
// ETag.
type VerifyError struct {
Expected ETag
Computed ETag
}
func (v VerifyError) Error() string {
return fmt.Sprintf("etag: expected ETag %q does not match computed ETag %q", v.Expected, v.Computed)
}

View File

@ -18,61 +18,141 @@ package hash
import (
"bytes"
"crypto/md5"
"encoding/base64"
"encoding/hex"
"errors"
"hash"
"io"
"github.com/minio/minio/pkg/etag"
sha256 "github.com/minio/sha256-simd"
)
// Reader writes what it reads from an io.Reader to an MD5 and SHA256 hash.Hash.
// Reader verifies that the content of the io.Reader matches the expected checksums.
// A Reader wraps an io.Reader and computes the MD5 checksum
// of the read content as ETag. Optionally, it also computes
// the SHA256 checksum of the content.
//
// If the reference values for the ETag and content SHA26
// are not empty then it will check whether the computed
// match the reference values.
type Reader struct {
src io.Reader
src io.Reader
bytesRead int64
size int64
actualSize int64
bytesRead int64
md5sum, sha256sum []byte // Byte values of md5sum, sha256sum of client sent values.
md5Hash, sha256Hash hash.Hash
checksum etag.ETag
contentSHA256 []byte
sha256 hash.Hash
}
// NewReader returns a new hash Reader which computes the MD5 sum and
// SHA256 sum (if set) of the provided io.Reader at EOF.
func NewReader(src io.Reader, size int64, md5Hex, sha256Hex string, actualSize int64, strictCompat bool) (*Reader, error) {
// NewReader returns a new Reader that wraps src and computes
// MD5 checksum of everything it reads as ETag.
//
// It also computes the SHA256 checksum of everything it reads
// if sha256Hex is not the empty string.
//
// If size resp. actualSize is unknown at the time of calling
// NewReader then it should be set to -1.
//
// NewReader may try merge the given size, MD5 and SHA256 values
// into src - if src is a Reader - to avoid computing the same
// checksums multiple times.
func NewReader(src io.Reader, size int64, md5Hex, sha256Hex string, actualSize int64) (*Reader, error) {
MD5, err := hex.DecodeString(md5Hex)
if err != nil {
return nil, BadDigest{ // TODO(aead): Return an error that indicates that an invalid ETag has been specified
ExpectedMD5: md5Hex,
CalculatedMD5: "",
}
}
SHA256, err := hex.DecodeString(sha256Hex)
if err != nil {
return nil, SHA256Mismatch{ // TODO(aead): Return an error that indicates that an invalid Content-SHA256 has been specified
ExpectedSHA256: sha256Hex,
CalculatedSHA256: "",
}
}
// Merge the size, MD5 and SHA256 values if src is a Reader.
// The size may be set to -1 by callers if unknown.
if r, ok := src.(*Reader); ok {
// Merge expectations and return parent.
return r.merge(size, md5Hex, sha256Hex, actualSize, strictCompat)
if r.bytesRead > 0 {
return nil, errors.New("hash: already read from hash reader")
}
if len(r.checksum) != 0 && len(MD5) != 0 && !etag.Equal(r.checksum, etag.ETag(MD5)) {
return nil, BadDigest{
ExpectedMD5: r.checksum.String(),
CalculatedMD5: md5Hex,
}
}
if len(r.contentSHA256) != 0 && len(SHA256) != 0 && !bytes.Equal(r.contentSHA256, SHA256) {
return nil, SHA256Mismatch{
ExpectedSHA256: hex.EncodeToString(r.contentSHA256),
CalculatedSHA256: sha256Hex,
}
}
if r.size >= 0 && size >= 0 && r.size != size {
return nil, ErrSizeMismatch{Want: r.size, Got: size}
}
r.checksum = etag.ETag(MD5)
r.contentSHA256 = SHA256
if r.size < 0 && size >= 0 {
r.src = etag.Wrap(io.LimitReader(r.src, size), r.src)
r.size = size
}
if r.actualSize <= 0 && actualSize >= 0 {
r.actualSize = actualSize
}
return r, nil
}
// Create empty reader and merge into that.
r := Reader{src: src, size: -1, actualSize: -1}
return r.merge(size, md5Hex, sha256Hex, actualSize, strictCompat)
var hash hash.Hash
if size >= 0 {
src = io.LimitReader(src, size)
}
if len(SHA256) != 0 {
hash = sha256.New()
}
return &Reader{
src: etag.NewReader(src, etag.ETag(MD5)),
size: size,
actualSize: actualSize,
checksum: etag.ETag(MD5),
contentSHA256: SHA256,
sha256: hash,
}, nil
}
func (r *Reader) Read(p []byte) (n int, err error) {
n, err = r.src.Read(p)
if n > 0 {
if r.md5Hash != nil {
r.md5Hash.Write(p[:n])
}
if r.sha256Hash != nil {
r.sha256Hash.Write(p[:n])
}
}
func (r *Reader) Read(p []byte) (int, error) {
n, err := r.src.Read(p)
r.bytesRead += int64(n)
// At io.EOF verify if the checksums are right.
if err == io.EOF {
if cerr := r.verify(); cerr != nil {
return 0, cerr
}
if r.sha256 != nil {
r.sha256.Write(p[:n])
}
return
if err == io.EOF { // Verify content SHA256, if set.
if r.sha256 != nil {
if sum := r.sha256.Sum(nil); !bytes.Equal(r.contentSHA256, sum) {
return n, SHA256Mismatch{
ExpectedSHA256: hex.EncodeToString(r.contentSHA256),
CalculatedSHA256: hex.EncodeToString(sum),
}
}
}
}
if err != nil && err != io.EOF {
if v, ok := err.(etag.VerifyError); ok {
return n, BadDigest{
ExpectedMD5: v.Expected.String(),
CalculatedMD5: v.Computed.String(),
}
}
}
return n, err
}
// Size returns the absolute number of bytes the Reader
@ -84,114 +164,58 @@ func (r *Reader) Size() int64 { return r.size }
// DecompressedSize - For compressed objects.
func (r *Reader) ActualSize() int64 { return r.actualSize }
// MD5 - returns byte md5 value
// ETag returns the ETag computed by an underlying etag.Tagger.
// If the underlying io.Reader does not implement etag.Tagger
// it returns nil.
func (r *Reader) ETag() etag.ETag {
if t, ok := r.src.(etag.Tagger); ok {
return t.ETag()
}
return nil
}
// MD5 returns the MD5 checksum set as reference value.
//
// It corresponds to the checksum that is expected and
// not the actual MD5 checksum of the content.
// Therefore, refer to MD5Current.
func (r *Reader) MD5() []byte {
return r.md5sum
return r.checksum
}
// MD5Current - returns byte md5 value of the current state
// of the md5 hash after reading the incoming content.
// NOTE: Calling this function multiple times might yield
// different results if they are intermixed with Reader.
// MD5Current returns the MD5 checksum of the content
// that has been read so far.
//
// Calling MD5Current again after reading more data may
// result in a different checksum.
func (r *Reader) MD5Current() []byte {
if r.md5Hash != nil {
return r.md5Hash.Sum(nil)
}
return nil
return r.ETag()[:]
}
// SHA256 - returns byte sha256 value
// SHA256 returns the SHA256 checksum set as reference value.
//
// It corresponds to the checksum that is expected and
// not the actual SHA256 checksum of the content.
func (r *Reader) SHA256() []byte {
return r.sha256sum
return r.contentSHA256
}
// MD5HexString returns hex md5 value.
// MD5HexString returns a hex representation of the MD5.
func (r *Reader) MD5HexString() string {
return hex.EncodeToString(r.md5sum)
return hex.EncodeToString(r.checksum)
}
// MD5Base64String returns base64 encoded MD5sum value.
// MD5Base64String returns a hex representation of the MD5.
func (r *Reader) MD5Base64String() string {
return base64.StdEncoding.EncodeToString(r.md5sum)
return base64.StdEncoding.EncodeToString(r.checksum)
}
// SHA256HexString returns hex sha256 value.
// SHA256HexString returns a hex representation of the SHA256.
func (r *Reader) SHA256HexString() string {
return hex.EncodeToString(r.sha256sum)
return hex.EncodeToString(r.contentSHA256)
}
// verify verifies if the computed MD5 sum and SHA256 sum are
// equal to the ones specified when creating the Reader.
func (r *Reader) verify() error {
if r.sha256Hash != nil && len(r.sha256sum) > 0 {
if sum := r.sha256Hash.Sum(nil); !bytes.Equal(r.sha256sum, sum) {
return SHA256Mismatch{hex.EncodeToString(r.sha256sum), hex.EncodeToString(sum)}
}
}
if r.md5Hash != nil && len(r.md5sum) > 0 {
if sum := r.md5Hash.Sum(nil); !bytes.Equal(r.md5sum, sum) {
return BadDigest{hex.EncodeToString(r.md5sum), hex.EncodeToString(sum)}
}
}
return nil
}
// merge another hash into this one.
// There cannot be conflicting information given.
func (r *Reader) merge(size int64, md5Hex, sha256Hex string, actualSize int64, strictCompat bool) (*Reader, error) {
if r.bytesRead > 0 {
return nil, errors.New("internal error: Already read from hash reader")
}
// Merge sizes.
// If not set before, just add it.
if r.size < 0 && size >= 0 {
r.src = io.LimitReader(r.src, size)
r.size = size
}
// If set before and set now they must match.
if r.size >= 0 && size >= 0 && r.size != size {
return nil, ErrSizeMismatch{Want: r.size, Got: size}
}
if r.actualSize <= 0 && actualSize >= 0 {
r.actualSize = actualSize
}
// Merge SHA256.
sha256sum, err := hex.DecodeString(sha256Hex)
if err != nil {
return nil, SHA256Mismatch{}
}
// If both are set, they must be the same.
if r.sha256Hash != nil && len(sha256sum) > 0 {
if !bytes.Equal(r.sha256sum, sha256sum) {
return nil, SHA256Mismatch{}
}
} else if len(sha256sum) > 0 {
r.sha256Hash = sha256.New()
r.sha256sum = sha256sum
}
// Merge MD5 Sum.
md5sum, err := hex.DecodeString(md5Hex)
if err != nil {
return nil, BadDigest{}
}
// If both are set, they must expect the same.
if r.md5Hash != nil && len(md5sum) > 0 {
if !bytes.Equal(r.md5sum, md5sum) {
return nil, BadDigest{}
}
} else if len(md5sum) > 0 || (r.md5Hash == nil && strictCompat) {
r.md5Hash = md5.New()
r.md5sum = md5sum
}
return r, nil
}
var _ io.Closer = (*Reader)(nil) // compiler check
// Close and release resources.
func (r *Reader) Close() error {
// Support the io.Closer interface.
return nil
}
func (r *Reader) Close() error { return nil }

View File

@ -27,7 +27,7 @@ import (
// Tests functions like Size(), MD5*(), SHA256*()
func TestHashReaderHelperMethods(t *testing.T) {
r, err := NewReader(bytes.NewReader([]byte("abcd")), 4, "e2fc714c4727ee9395f324cd2e7f331f", "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589", 4, false)
r, err := NewReader(bytes.NewReader([]byte("abcd")), 4, "e2fc714c4727ee9395f324cd2e7f331f", "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589", 4)
if err != nil {
t.Fatal(err)
}
@ -109,13 +109,13 @@ func TestHashReaderVerification(t *testing.T) {
},
{
desc: "Nested hash reader NewReader() should merge.",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4),
size: 4,
actualSize: 4,
},
{
desc: "Incorrect sha256, nested",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4),
size: 4,
actualSize: 4,
sha256hex: "50d858e0985ecc7f60418aaf0cc5ab587f42c2570a884095a9e8ccacd0f6545c",
@ -126,28 +126,28 @@ func TestHashReaderVerification(t *testing.T) {
},
{
desc: "Correct sha256, nested",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4),
size: 4,
actualSize: 4,
sha256hex: "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589",
},
{
desc: "Correct sha256, nested, truncated",
src: mustReader(t, bytes.NewReader([]byte("abcd-more-stuff-to-be ignored")), 4, "", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd-more-stuff-to-be ignored")), 4, "", "", 4),
size: 4,
actualSize: -1,
sha256hex: "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589",
},
{
desc: "Correct sha256, nested, truncated, swapped",
src: mustReader(t, bytes.NewReader([]byte("abcd-more-stuff-to-be ignored")), 4, "", "", -1, false),
src: mustReader(t, bytes.NewReader([]byte("abcd-more-stuff-to-be ignored")), 4, "", "", -1),
size: 4,
actualSize: -1,
sha256hex: "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589",
},
{
desc: "Incorrect MD5, nested",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4),
size: 4,
actualSize: 4,
md5hex: "0773da587b322af3a8718cb418a715ce",
@ -165,7 +165,7 @@ func TestHashReaderVerification(t *testing.T) {
},
{
desc: "Correct MD5, nested",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4),
size: 4,
actualSize: 4,
md5hex: "e2fc714c4727ee9395f324cd2e7f331f",
@ -180,7 +180,7 @@ func TestHashReaderVerification(t *testing.T) {
},
{
desc: "Correct MD5, nested, truncated",
src: mustReader(t, bytes.NewReader([]byte("abcd-morestuff")), -1, "", "", -1, false),
src: mustReader(t, bytes.NewReader([]byte("abcd-morestuff")), -1, "", "", -1),
size: 4,
actualSize: 4,
md5hex: "e2fc714c4727ee9395f324cd2e7f331f",
@ -188,7 +188,7 @@ func TestHashReaderVerification(t *testing.T) {
}
for i, testCase := range testCases {
t.Run(fmt.Sprintf("case-%d", i+1), func(t *testing.T) {
r, err := NewReader(testCase.src, testCase.size, testCase.md5hex, testCase.sha256hex, testCase.actualSize, false)
r, err := NewReader(testCase.src, testCase.size, testCase.md5hex, testCase.sha256hex, testCase.actualSize)
if err != nil {
t.Fatalf("Test %q: Initializing reader failed %s", testCase.desc, err)
}
@ -202,8 +202,8 @@ func TestHashReaderVerification(t *testing.T) {
}
}
func mustReader(t *testing.T, src io.Reader, size int64, md5Hex, sha256Hex string, actualSize int64, strictCompat bool) *Reader {
r, err := NewReader(src, size, md5Hex, sha256Hex, actualSize, strictCompat)
func mustReader(t *testing.T, src io.Reader, size int64, md5Hex, sha256Hex string, actualSize int64) *Reader {
r, err := NewReader(src, size, md5Hex, sha256Hex, actualSize)
if err != nil {
t.Fatal(err)
}
@ -219,63 +219,57 @@ func TestHashReaderInvalidArguments(t *testing.T) {
actualSize int64
md5hex, sha256hex string
success bool
expectedErr error
strict bool
}{
{
desc: "Invalid md5sum NewReader() will fail.",
src: bytes.NewReader([]byte("abcd")),
size: 4,
actualSize: 4,
md5hex: "invalid-md5",
success: false,
expectedErr: BadDigest{},
desc: "Invalid md5sum NewReader() will fail.",
src: bytes.NewReader([]byte("abcd")),
size: 4,
actualSize: 4,
md5hex: "invalid-md5",
success: false,
},
{
desc: "Invalid sha256 NewReader() will fail.",
src: bytes.NewReader([]byte("abcd")),
size: 4,
actualSize: 4,
sha256hex: "invalid-sha256",
success: false,
expectedErr: SHA256Mismatch{},
desc: "Invalid sha256 NewReader() will fail.",
src: bytes.NewReader([]byte("abcd")),
size: 4,
actualSize: 4,
sha256hex: "invalid-sha256",
success: false,
},
{
desc: "Nested hash reader NewReader() should merge.",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "", 4),
size: 4,
actualSize: 4,
success: true,
},
{
desc: "Mismatching sha256",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589", 4, false),
size: 4,
actualSize: 4,
sha256hex: "50d858e0985ecc7f60418aaf0cc5ab587f42c2570a884095a9e8ccacd0f6545c",
success: false,
expectedErr: SHA256Mismatch{},
desc: "Mismatching sha256",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589", 4),
size: 4,
actualSize: 4,
sha256hex: "50d858e0985ecc7f60418aaf0cc5ab587f42c2570a884095a9e8ccacd0f6545c",
success: false,
},
{
desc: "Correct sha256",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "", "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589", 4),
size: 4,
actualSize: 4,
sha256hex: "88d4266fd4e6338d13b845fcf289579d209c897823b9217da3e161936f031589",
success: true,
},
{
desc: "Mismatching MD5",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "e2fc714c4727ee9395f324cd2e7f331f", "", 4, false),
size: 4,
actualSize: 4,
md5hex: "0773da587b322af3a8718cb418a715ce",
success: false,
expectedErr: BadDigest{},
desc: "Mismatching MD5",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "e2fc714c4727ee9395f324cd2e7f331f", "", 4),
size: 4,
actualSize: 4,
md5hex: "0773da587b322af3a8718cb418a715ce",
success: false,
},
{
desc: "Correct MD5",
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "e2fc714c4727ee9395f324cd2e7f331f", "", 4, false),
src: mustReader(t, bytes.NewReader([]byte("abcd")), 4, "e2fc714c4727ee9395f324cd2e7f331f", "", 4),
size: 4,
actualSize: 4,
md5hex: "e2fc714c4727ee9395f324cd2e7f331f",
@ -289,29 +283,23 @@ func TestHashReaderInvalidArguments(t *testing.T) {
success: true,
},
{
desc: "Nested, size mismatch",
src: mustReader(t, bytes.NewReader([]byte("abcd-morestuff")), 4, "", "", -1, false),
size: 2,
actualSize: -1,
success: false,
expectedErr: ErrSizeMismatch{Want: 4, Got: 2},
desc: "Nested, size mismatch",
src: mustReader(t, bytes.NewReader([]byte("abcd-morestuff")), 4, "", "", -1),
size: 2,
actualSize: -1,
success: false,
},
}
for i, testCase := range testCases {
t.Run(fmt.Sprintf("case-%d", i+1), func(t *testing.T) {
_, err := NewReader(testCase.src, testCase.size, testCase.md5hex, testCase.sha256hex, testCase.actualSize, testCase.strict)
_, err := NewReader(testCase.src, testCase.size, testCase.md5hex, testCase.sha256hex, testCase.actualSize)
if err != nil && testCase.success {
t.Errorf("Test %q: Expected success, but got error %s instead", testCase.desc, err)
}
if err == nil && !testCase.success {
t.Errorf("Test %q: Expected error, but got success", testCase.desc)
}
if !testCase.success {
if err != testCase.expectedErr {
t.Errorf("Test %q: Expected error %v, but got %v", testCase.desc, testCase.expectedErr, err)
}
}
})
}
}