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136 lines
3.3 KiB
136 lines
3.3 KiB
/*
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* Minio Cloud Storage, (C) 2017 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 hash
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import (
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"bytes"
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"crypto/md5"
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"crypto/sha256"
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"encoding/hex"
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"errors"
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"hash"
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"io"
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)
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// Reader writes what it reads from an io.Reader to an MD5 and SHA256 hash.Hash.
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// Reader verifies that the content of the io.Reader matches the expected checksums.
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type Reader struct {
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src io.Reader
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size int64
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md5sum, sha256sum []byte // Byte values of md5sum, sha256sum of client sent values.
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md5Hash, sha256Hash hash.Hash
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}
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// NewReader returns a new hash Reader which computes the MD5 sum and
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// SHA256 sum (if set) of the provided io.Reader at EOF.
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func NewReader(src io.Reader, size int64, md5Hex, sha256Hex string) (*Reader, error) {
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if _, ok := src.(*Reader); ok {
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return nil, errors.New("Nesting of Reader detected, not allowed")
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}
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sha256sum, err := hex.DecodeString(sha256Hex)
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if err != nil {
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return nil, err
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}
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md5sum, err := hex.DecodeString(md5Hex)
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if err != nil {
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return nil, err
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}
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var (
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md5Hash hash.Hash
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sha256Hash hash.Hash
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)
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if len(md5sum) != 0 {
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md5Hash = md5.New()
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}
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if len(sha256sum) != 0 {
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sha256Hash = sha256.New()
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}
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return &Reader{
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md5sum: md5sum,
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sha256sum: sha256sum,
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src: io.LimitReader(src, size),
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size: size,
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md5Hash: md5Hash,
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sha256Hash: sha256Hash,
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}, nil
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}
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func (r *Reader) Read(p []byte) (n int, err error) {
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n, err = r.src.Read(p)
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if n > 0 {
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if r.md5Hash != nil {
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r.md5Hash.Write(p[:n])
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}
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if r.sha256Hash != nil {
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r.sha256Hash.Write(p[:n])
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}
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}
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// At io.EOF verify if the checksums are right.
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if err == io.EOF {
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if cerr := r.Verify(); cerr != nil {
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return 0, cerr
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}
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}
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return
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}
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// Size returns the absolute number of bytes the Reader
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// will return during reading. It returns -1 for unlimited
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// data.
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func (r *Reader) Size() int64 { return r.size }
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// MD5 - returns byte md5 value
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func (r *Reader) MD5() []byte {
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return r.md5sum
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}
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// SHA256 - returns byte sha256 value
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func (r *Reader) SHA256() []byte {
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return r.sha256sum
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}
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// MD5HexString returns hex md5 value.
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func (r *Reader) MD5HexString() string {
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return hex.EncodeToString(r.md5sum)
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}
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// SHA256HexString returns hex sha256 value.
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func (r *Reader) SHA256HexString() string {
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return hex.EncodeToString(r.sha256sum)
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}
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// Verify verifies if the computed MD5 sum and SHA256 sum are
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// equal to the ones specified when creating the Reader.
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func (r *Reader) Verify() error {
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if r.sha256Hash != nil {
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if sum := r.sha256Hash.Sum(nil); !bytes.Equal(r.sha256sum, sum) {
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return SHA256Mismatch{hex.EncodeToString(r.sha256sum), hex.EncodeToString(sum)}
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}
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}
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if r.md5Hash != nil {
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if sum := r.md5Hash.Sum(nil); !bytes.Equal(r.md5sum, sum) {
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return BadDigest{hex.EncodeToString(r.md5sum), hex.EncodeToString(sum)}
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}
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}
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return nil
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}
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