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Implement runtime.Framer for CBOR Sequences.
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/* | ||
Copyright 2024 The Kubernetes 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. | ||
*/ | ||
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package cbor | ||
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import ( | ||
"io" | ||
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"k8s.io/apimachinery/pkg/runtime" | ||
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"github.com/fxamacker/cbor/v2" | ||
) | ||
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// NewFramer returns a runtime.Framer based on RFC 8742 CBOR Sequences. Each frame contains exactly | ||
// one encoded CBOR data item. | ||
func NewFramer() runtime.Framer { | ||
return framer{} | ||
} | ||
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var _ runtime.Framer = framer{} | ||
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type framer struct{} | ||
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func (framer) NewFrameReader(rc io.ReadCloser) io.ReadCloser { | ||
return &frameReader{ | ||
decoder: cbor.NewDecoder(rc), | ||
closer: rc, | ||
} | ||
} | ||
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func (framer) NewFrameWriter(w io.Writer) io.Writer { | ||
// Each data item in a CBOR sequence is self-delimiting (like JSON objects). | ||
return w | ||
} | ||
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type frameReader struct { | ||
decoder *cbor.Decoder | ||
closer io.Closer | ||
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overflow []byte | ||
} | ||
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func (fr *frameReader) Read(dst []byte) (int, error) { | ||
if len(fr.overflow) > 0 { | ||
// We read a frame that was too large for the destination slice in a previous call | ||
// to Read and have bytes left over. | ||
n := copy(dst, fr.overflow) | ||
if n < len(fr.overflow) { | ||
fr.overflow = fr.overflow[n:] | ||
return n, io.ErrShortBuffer | ||
} | ||
fr.overflow = nil | ||
return n, nil | ||
} | ||
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// The Reader contract allows implementations to use all of dst[0:len(dst)] as scratch | ||
// space, even if n < len(dst), but it does not allow implementations to use | ||
// dst[len(dst):cap(dst)]. Slicing it up-front allows us to append to it without worrying | ||
// about overwriting dst[len(dst):cap(dst)]. | ||
m := cbor.RawMessage(dst[0:0:len(dst)]) | ||
if err := fr.decoder.Decode(&m); err != nil { | ||
return 0, err | ||
} | ||
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if len(m) > len(dst) { | ||
// The frame was too big, m has a newly-allocated underlying array to accommodate | ||
// it. | ||
fr.overflow = m[len(dst):] | ||
return copy(dst, m), io.ErrShortBuffer | ||
} | ||
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return len(m), nil | ||
} | ||
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func (fr *frameReader) Close() error { | ||
return fr.closer.Close() | ||
} |
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/* | ||
Copyright 2024 The Kubernetes 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. | ||
*/ | ||
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package cbor_test | ||
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import ( | ||
"bytes" | ||
"errors" | ||
"io" | ||
"testing" | ||
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"k8s.io/apimachinery/pkg/runtime/serializer/cbor" | ||
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"github.com/google/go-cmp/cmp" | ||
) | ||
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// TestFrameReaderReadError tests that the frame reader does not resume after encountering a | ||
// well-formedness error in the input stream. According to RFC 8742 Section 2.8: "[...] if any data | ||
// item in the sequence is not well formed, it is not possible to reliably decode the rest of the | ||
// sequence." | ||
func TestFrameReaderReadError(t *testing.T) { | ||
input := []byte{ | ||
0xff, // ill-formed initial break | ||
0xa0, // followed by well-formed empty map | ||
} | ||
fr := cbor.NewFramer().NewFrameReader(io.NopCloser(bytes.NewReader(input))) | ||
for i := 0; i < 3; i++ { | ||
n, err := fr.Read(nil) | ||
if err == nil || errors.Is(err, io.ErrShortBuffer) { | ||
t.Fatalf("expected a non-nil error other than io.ErrShortBuffer, got: %v", err) | ||
} | ||
if n != 0 { | ||
t.Fatalf("expected 0 bytes read on error, got %d", n) | ||
} | ||
} | ||
} | ||
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func TestFrameReaderRead(t *testing.T) { | ||
type ChunkedFrame [][]byte | ||
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for _, tc := range []struct { | ||
Name string | ||
Frames []ChunkedFrame | ||
}{ | ||
{ | ||
Name: "consecutive frames", | ||
Frames: []ChunkedFrame{ | ||
[][]byte{{0xa0}}, | ||
[][]byte{{0xa0}}, | ||
}, | ||
}, | ||
{ | ||
Name: "zero-length destination buffer", | ||
Frames: []ChunkedFrame{ | ||
[][]byte{{}, {0xa0}}, | ||
}, | ||
}, | ||
{ | ||
Name: "overflow", | ||
Frames: []ChunkedFrame{ | ||
[][]byte{ | ||
{0x43}, | ||
{'x'}, | ||
{'y', 'z'}, | ||
}, | ||
[][]byte{ | ||
{0xa1, 0x43, 'f', 'o', 'o'}, | ||
{'b'}, | ||
{'a', 'r'}, | ||
}, | ||
}, | ||
}, | ||
} { | ||
t.Run(tc.Name, func(t *testing.T) { | ||
var concatenation []byte | ||
for _, f := range tc.Frames { | ||
for _, c := range f { | ||
concatenation = append(concatenation, c...) | ||
} | ||
} | ||
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fr := cbor.NewFramer().NewFrameReader(io.NopCloser(bytes.NewReader(concatenation))) | ||
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for _, frame := range tc.Frames { | ||
var want, got []byte | ||
for i, chunk := range frame { | ||
dst := make([]byte, len(chunk), 2*len(chunk)) | ||
for i := len(dst); i < cap(dst); i++ { | ||
dst[:cap(dst)][i] = 0xff | ||
} | ||
n, err := fr.Read(dst) | ||
if n != len(chunk) { | ||
t.Errorf("expected %d bytes read, got %d", len(chunk), n) | ||
} | ||
if i == len(frame)-1 && err != nil { | ||
t.Errorf("unexpected non-nil error on last read of frame: %v", err) | ||
} else if i < len(frame)-1 && !errors.Is(err, io.ErrShortBuffer) { | ||
t.Errorf("expected io.ErrShortBuffer on all but the last read of a frame, got: %v", err) | ||
} | ||
for i := len(dst); i < cap(dst); i++ { | ||
if dst[:cap(dst)][i] != 0xff { | ||
t.Errorf("read mutated underlying array beyond slice length: %#v", dst[len(dst):cap(dst)]) | ||
break | ||
} | ||
} | ||
want = append(want, chunk...) | ||
got = append(got, dst...) | ||
} | ||
if diff := cmp.Diff(want, got); diff != "" { | ||
t.Errorf("reassembled frame differs:\n%s", diff) | ||
} | ||
} | ||
}) | ||
} | ||
} | ||
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type fakeReadCloser struct { | ||
err error | ||
} | ||
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func (rc fakeReadCloser) Read(_ []byte) (int, error) { | ||
return 0, nil | ||
} | ||
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func (rc fakeReadCloser) Close() error { | ||
return rc.err | ||
} | ||
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func TestFrameReaderClose(t *testing.T) { | ||
want := errors.New("test") | ||
if got := cbor.NewFramer().NewFrameReader(fakeReadCloser{err: want}).Close(); !errors.Is(got, want) { | ||
t.Errorf("got error %v, want %v", got, want) | ||
} | ||
} |