70 lines
1.4 KiB
Go
70 lines
1.4 KiB
Go
package sarama
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import (
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"encoding/binary"
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"fmt"
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"hash/crc32"
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)
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type crcPolynomial int8
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const (
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crcIEEE crcPolynomial = iota
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crcCastagnoli
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)
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var castagnoliTable = crc32.MakeTable(crc32.Castagnoli)
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// crc32Field implements the pushEncoder and pushDecoder interfaces for calculating CRC32s.
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type crc32Field struct {
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startOffset int
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polynomial crcPolynomial
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}
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func (c *crc32Field) saveOffset(in int) {
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c.startOffset = in
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}
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func (c *crc32Field) reserveLength() int {
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return 4
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}
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func newCRC32Field(polynomial crcPolynomial) *crc32Field {
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return &crc32Field{polynomial: polynomial}
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}
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func (c *crc32Field) run(curOffset int, buf []byte) error {
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crc, err := c.crc(curOffset, buf)
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if err != nil {
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return err
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}
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binary.BigEndian.PutUint32(buf[c.startOffset:], crc)
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return nil
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}
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func (c *crc32Field) check(curOffset int, buf []byte) error {
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crc, err := c.crc(curOffset, buf)
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if err != nil {
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return err
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}
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expected := binary.BigEndian.Uint32(buf[c.startOffset:])
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if crc != expected {
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return PacketDecodingError{fmt.Sprintf("CRC didn't match expected %#x got %#x", expected, crc)}
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}
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return nil
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}
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func (c *crc32Field) crc(curOffset int, buf []byte) (uint32, error) {
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var tab *crc32.Table
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switch c.polynomial {
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case crcIEEE:
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tab = crc32.IEEETable
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case crcCastagnoli:
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tab = castagnoliTable
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default:
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return 0, PacketDecodingError{"invalid CRC type"}
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}
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return crc32.Checksum(buf[c.startOffset+4:curOffset], tab), nil
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}
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