108 lines
2.6 KiB
Go
108 lines
2.6 KiB
Go
// Copyright (c) HashiCorp, Inc.
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// SPDX-License-Identifier: MPL-2.0
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package bsr
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import (
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"bytes"
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"compress/gzip"
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"context"
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"encoding/binary"
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"fmt"
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"hash/crc32"
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"io"
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)
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// ChunkEncoder will encode a chunk and write it to the writer.
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// It will compress the chunk data based on the compression.
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type ChunkEncoder struct {
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w io.Writer
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compression Compression
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encryption Encryption
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}
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// NewChunkEncoder creates a ChunkEncoder.
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func NewChunkEncoder(ctx context.Context, w io.Writer, c Compression, e Encryption) (*ChunkEncoder, error) {
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const op = "bsr.NewChunkEncoder"
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if w == nil {
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return nil, fmt.Errorf("%s: writer cannot be nil: %w", op, ErrInvalidParameter)
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}
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if !ValidCompression(c) {
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return nil, fmt.Errorf("%s: invalid compression: %w", op, ErrInvalidParameter)
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}
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if !ValidEncryption(e) {
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return nil, fmt.Errorf("%s: invalid encryption: %w", op, ErrInvalidParameter)
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}
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return &ChunkEncoder{
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w: w,
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compression: c,
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encryption: e,
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}, nil
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}
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// Encode serializes a Chunk and writes it with the encoder's writer.
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func (e ChunkEncoder) Encode(ctx context.Context, c Chunk) (int, error) {
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data, err := c.MarshalData(ctx)
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if err != nil {
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return 0, err
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}
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var buf bytes.Buffer
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var compressor io.WriteCloser
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switch c.GetType() {
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// Header should not be compressed since we need to read it prior to knowing
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// what compression was used to check the compression bit.
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// End should not be compressed since it has no data and compressing an empty
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// byte slice just adds data in the form of the compression magic strings.
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case ChunkHeader, ChunkEnd:
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compressor = newNullCompressionWriter(&buf)
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default:
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switch e.compression {
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case GzipCompression:
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compressor = gzip.NewWriter(&buf)
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default:
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compressor = newNullCompressionWriter(&buf)
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}
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}
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if _, err := compressor.Write(data); err != nil {
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return 0, err
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}
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compressor.Close()
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length := buf.Len()
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t := c.GetTimestamp().marshal()
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// calculate CRC for protocol+type+dir+timestamp+data
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crced := make([]byte, 0, chunkBaseSize+length)
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crced = append(crced, c.GetProtocol()...)
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crced = append(crced, c.GetType()...)
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crced = append(crced, byte(c.GetDirection()))
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crced = append(crced, t...)
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crced = append(crced, buf.Bytes()...)
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crc := crc32.NewIEEE()
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crc.Write(crced)
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d := make([]byte, 0, chunkBaseSize+length+crcSize)
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d = binary.BigEndian.AppendUint32(d, uint32(length))
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d = append(d, crced...)
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d = binary.BigEndian.AppendUint32(d, crc.Sum32())
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return e.w.Write(d)
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}
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// Close closes the encoder.
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func (e *ChunkEncoder) Close() error {
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var i interface{} = e.w
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v, ok := i.(io.WriteCloser)
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if ok {
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return v.Close()
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}
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return nil
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}
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