142 lines
3.5 KiB
Go
142 lines
3.5 KiB
Go
/*
|
|
Copyright The ORAS Authors.
|
|
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 content
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
|
|
"github.com/opencontainers/go-digest"
|
|
ocispec "github.com/opencontainers/image-spec/specs-go/v1"
|
|
)
|
|
|
|
var (
|
|
// ErrInvalidDescriptorSize is returned by ReadAll() when
|
|
// the descriptor has an invalid size.
|
|
ErrInvalidDescriptorSize = errors.New("invalid descriptor size")
|
|
|
|
// ErrMismatchedDigest is returned by ReadAll() when
|
|
// the descriptor has an invalid digest.
|
|
ErrMismatchedDigest = errors.New("mismatched digest")
|
|
|
|
// ErrTrailingData is returned by ReadAll() when
|
|
// there exists trailing data unread when the read terminates.
|
|
ErrTrailingData = errors.New("trailing data")
|
|
)
|
|
|
|
var (
|
|
// errEarlyVerify is returned by VerifyReader.Verify() when
|
|
// Verify() is called before completing reading the entire content blob.
|
|
errEarlyVerify = errors.New("early verify")
|
|
)
|
|
|
|
// VerifyReader reads the content described by its descriptor and verifies
|
|
// against its size and digest.
|
|
type VerifyReader struct {
|
|
base *io.LimitedReader
|
|
verifier digest.Verifier
|
|
verified bool
|
|
err error
|
|
}
|
|
|
|
// Read reads up to len(p) bytes into p. It returns the number of bytes
|
|
// read (0 <= n <= len(p)) and any error encountered.
|
|
func (vr *VerifyReader) Read(p []byte) (n int, err error) {
|
|
if vr.err != nil {
|
|
return 0, vr.err
|
|
}
|
|
|
|
n, err = vr.base.Read(p)
|
|
if err != nil {
|
|
if err == io.EOF && vr.base.N > 0 {
|
|
err = io.ErrUnexpectedEOF
|
|
}
|
|
vr.err = err
|
|
}
|
|
return
|
|
}
|
|
|
|
// Verify verifies the read content against the size and the digest.
|
|
func (vr *VerifyReader) Verify() error {
|
|
if vr.verified {
|
|
return nil
|
|
}
|
|
if vr.err == nil {
|
|
if vr.base.N > 0 {
|
|
return errEarlyVerify
|
|
}
|
|
} else if vr.err != io.EOF {
|
|
return vr.err
|
|
}
|
|
|
|
if err := ensureEOF(vr.base.R); err != nil {
|
|
vr.err = err
|
|
return vr.err
|
|
}
|
|
if !vr.verifier.Verified() {
|
|
vr.err = ErrMismatchedDigest
|
|
return vr.err
|
|
}
|
|
|
|
vr.verified = true
|
|
vr.err = io.EOF
|
|
return nil
|
|
}
|
|
|
|
// NewVerifyReader wraps r for reading content with verification against desc.
|
|
func NewVerifyReader(r io.Reader, desc ocispec.Descriptor) *VerifyReader {
|
|
verifier := desc.Digest.Verifier()
|
|
lr := &io.LimitedReader{
|
|
R: io.TeeReader(r, verifier),
|
|
N: desc.Size,
|
|
}
|
|
return &VerifyReader{
|
|
base: lr,
|
|
verifier: verifier,
|
|
}
|
|
}
|
|
|
|
// ReadAll safely reads the content described by the descriptor.
|
|
// The read content is verified against the size and the digest
|
|
// using a VerifyReader.
|
|
func ReadAll(r io.Reader, desc ocispec.Descriptor) ([]byte, error) {
|
|
if desc.Size < 0 {
|
|
return nil, ErrInvalidDescriptorSize
|
|
}
|
|
buf := make([]byte, desc.Size)
|
|
|
|
vr := NewVerifyReader(r, desc)
|
|
if _, err := io.ReadFull(vr, buf); err != nil {
|
|
return nil, fmt.Errorf("read failed: %w", err)
|
|
}
|
|
if err := vr.Verify(); err != nil {
|
|
return nil, err
|
|
}
|
|
return buf, nil
|
|
}
|
|
|
|
// ensureEOF ensures the read operation ends with an EOF and no
|
|
// trailing data is present.
|
|
func ensureEOF(r io.Reader) error {
|
|
var peek [1]byte
|
|
_, err := io.ReadFull(r, peek[:])
|
|
if err != io.EOF {
|
|
return ErrTrailingData
|
|
}
|
|
return nil
|
|
}
|