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106 lines
3.5 KiB
106 lines
3.5 KiB
// Protocol Buffers for Go with Gadgets
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//
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// Copyright (c) 2013, The GoGo Authors. All rights reserved.
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// http://github.com/gogo/protobuf
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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// Modified from original GoGo Protobuf to not buffer the reader.
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package protoio
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"io"
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"github.com/gogo/protobuf/proto"
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)
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// NewDelimitedReader reads varint-delimited Protobuf messages from a reader.
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// Unlike the gogoproto NewDelimitedReader, this does not buffer the reader,
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// which may cause poor performance but is necessary when only reading single
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// messages (e.g. in the p2p package). It also returns the number of bytes
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// read, which is necessary for the p2p package.
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func NewDelimitedReader(r io.Reader, maxSize int) ReadCloser {
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var closer io.Closer
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if c, ok := r.(io.Closer); ok {
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closer = c
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}
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return &varintReader{r, nil, maxSize, closer}
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}
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type varintReader struct {
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r io.Reader
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buf []byte
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maxSize int
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closer io.Closer
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}
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func (r *varintReader) ReadMsg(msg proto.Message) (int, error) {
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// ReadUvarint needs an io.ByteReader, and we also need to keep track of the
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// number of bytes read, so we use our own byteReader. This can't be
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// buffered, so the caller should pass a buffered io.Reader to avoid poor
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// performance.
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byteReader := newByteReader(r.r)
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l, err := binary.ReadUvarint(byteReader)
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n := byteReader.bytesRead
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if err != nil {
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return n, err
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}
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// Make sure length doesn't overflow the native int size (e.g. 32-bit),
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// and that the returned sum of n+length doesn't overflow either.
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length := int(l)
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if l >= uint64(^uint(0)>>1) || length < 0 || n+length < 0 {
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return n, fmt.Errorf("invalid out-of-range message length %v", l)
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}
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if length > r.maxSize {
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return n, fmt.Errorf("message exceeds max size (%v > %v)", length, r.maxSize)
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}
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if len(r.buf) < length {
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r.buf = make([]byte, length)
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}
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buf := r.buf[:length]
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nr, err := io.ReadFull(r.r, buf)
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n += nr
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if err != nil {
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return n, err
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}
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return n, proto.Unmarshal(buf, msg)
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}
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func (r *varintReader) Close() error {
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if r.closer != nil {
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return r.closer.Close()
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}
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return nil
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}
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func UnmarshalDelimited(data []byte, msg proto.Message) error {
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_, err := NewDelimitedReader(bytes.NewReader(data), len(data)).ReadMsg(msg)
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return err
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}
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