61 lines
1.6 KiB
Go
61 lines
1.6 KiB
Go
package contentenc
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// Per-file header
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//
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// Format: [ "Version" uint16 big endian ] [ "Id" 16 random bytes ]
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import (
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"encoding/binary"
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"fmt"
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"github.com/rfjakob/gocryptfs/internal/cryptocore"
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)
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const (
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// Current On-Disk-Format version
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CurrentVersion = 2
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HEADER_VERSION_LEN = 2 // uint16
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HEADER_ID_LEN = 16 // 128 bit random file id
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HEADER_LEN = HEADER_VERSION_LEN + HEADER_ID_LEN // Total header length
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)
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type FileHeader struct {
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Version uint16
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Id []byte
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}
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// Pack - serialize fileHeader object
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func (h *FileHeader) Pack() []byte {
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if len(h.Id) != HEADER_ID_LEN || h.Version != CurrentVersion {
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panic("FileHeader object not properly initialized")
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}
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buf := make([]byte, HEADER_LEN)
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binary.BigEndian.PutUint16(buf[0:HEADER_VERSION_LEN], h.Version)
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copy(buf[HEADER_VERSION_LEN:], h.Id)
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return buf
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}
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// ParseHeader - parse "buf" into fileHeader object
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func ParseHeader(buf []byte) (*FileHeader, error) {
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if len(buf) != HEADER_LEN {
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return nil, fmt.Errorf("ParseHeader: invalid length: got %d, want %d", len(buf), HEADER_LEN)
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}
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var h FileHeader
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h.Version = binary.BigEndian.Uint16(buf[0:HEADER_VERSION_LEN])
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if h.Version != CurrentVersion {
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return nil, fmt.Errorf("ParseHeader: invalid version: got %d, want %d", h.Version, CurrentVersion)
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}
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h.Id = buf[HEADER_VERSION_LEN:]
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return &h, nil
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}
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// RandomHeader - create new fileHeader object with random Id
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func RandomHeader() *FileHeader {
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var h FileHeader
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h.Version = CurrentVersion
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h.Id = cryptocore.RandBytes(HEADER_ID_LEN)
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return &h
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}
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