62 lines
1.2 KiB
Go
62 lines
1.2 KiB
Go
package kgm
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import (
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"fmt"
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"io"
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"github.com/unlock-music/cli/algo/common"
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)
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type Decoder struct {
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header header
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cipher common.StreamDecoder
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rd io.ReadSeeker
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offset int
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}
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func NewDecoder(rd io.ReadSeeker) common.Decoder {
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return &Decoder{rd: rd}
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}
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var kgmCryptoInitializers = map[uint32]func(header *header) (common.StreamDecoder, error){
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3: newKgmCryptoV3,
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}
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func (d *Decoder) Validate() error {
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if err := d.header.FromFile(d.rd); err != nil {
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return err
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}
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// TODO; validate crypto version
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initializer, ok := kgmCryptoInitializers[d.header.CryptoVersion]
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if !ok {
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return fmt.Errorf("kgm: unsupported crypto version %d", d.header.CryptoVersion)
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}
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var err error
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d.cipher, err = initializer(&d.header)
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if err != nil {
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return fmt.Errorf("kgm: failed to initialize crypto: %w", err)
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}
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return nil
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}
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func (d *Decoder) Read(buf []byte) (int, error) {
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n, err := d.rd.Read(buf)
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if n > 0 {
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d.cipher.Decrypt(buf[:n], d.offset)
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d.offset += n
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}
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return n, err
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}
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func init() {
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// Kugou
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common.RegisterDecoder("kgm", false, NewDecoder)
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common.RegisterDecoder("kgma", false, NewDecoder)
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// Viper
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common.RegisterDecoder("vpr", false, NewDecoder)
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}
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